Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.
A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE.
High molecular weight proteins found in the MICROTUBULES of the cytoskeletal system. Under certain conditions they are required for TUBULIN assembly into the microtubules and stabilize the assembled microtubules.
Nocodazole is an antineoplastic agent which exerts its effect by depolymerizing microtubules.
A major alkaloid from Colchicum autumnale L. and found also in other Colchicum species. Its primary therapeutic use is in the treatment of gout, but it has been used also in the therapy of familial Mediterranean fever (PERIODIC DISEASE).
A microtubule-associated mechanical adenosine triphosphatase, that uses the energy of ATP hydrolysis to move organelles along microtubules toward the plus end of the microtubule. The protein is found in squid axoplasm, optic lobes, and in bovine brain. Bovine kinesin is a heterotetramer composed of two heavy (120 kDa) and two light (62 kDa) chains. EC 3.6.1.-.
A microtubule structure that forms during CELL DIVISION. It consists of two SPINDLE POLES, and sets of MICROTUBULES that may include the astral microtubules, the polar microtubules, and the kinetochore microtubules.
Proteins found in the microtubules.
A family of multisubunit cytoskeletal motor proteins that use the energy of ATP hydrolysis to power a variety of cellular functions. Dyneins fall into two major classes based upon structural and functional criteria.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species.
Agents that interact with TUBULIN to inhibit or promote polymerization of MICROTUBULES.
The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.
An alkaloid isolated from Colchicum autumnale L. and used as an antineoplastic.
The cell center, consisting of a pair of CENTRIOLES surrounded by a cloud of amorphous material called the pericentriolar region. During interphase, the centrosome nucleates microtubule outgrowth. The centrosome duplicates and, during mitosis, separates to form the two poles of the mitotic spindle (MITOTIC SPINDLE APPARATUS).
Large multiprotein complexes that bind the centromeres of the chromosomes to the microtubules of the mitotic spindle during metaphase in the cell cycle.
An organization of cells into an organ-like structure. Organoids can be generated in culture. They are also found in certain neoplasms.
A cyclodecane isolated from the bark of the Pacific yew tree, TAXUS BREVIFOLIA. It stabilizes MICROTUBULES in their polymerized form leading to cell death.
Proteins that are involved in or cause CELL MOVEMENT such as the rotary structures (flagellar motor) or the structures whose movement is directed along cytoskeletal filaments (MYOSIN; KINESIN; and DYNEIN motor families).
An amorphous region of electron dense material in the cytoplasm from which the MICROTUBULES polymerization is nucleated. The pericentriolar region of the CENTROSOME which surrounds the CENTRIOLES is an example.
The phase of cell nucleus division following METAPHASE, in which the CHROMATIDS separate and migrate to opposite poles of the spindle.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.
Self-replicating, short, fibrous, rod-shaped organelles. Each centriole is a short cylinder containing nine pairs of peripheral microtubules, arranged so as to form the wall of the cylinder.
Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.
Compounds based on 4-aminobenzenesulfonamide. The '-anil-' part of the name refers to aniline.
Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.
Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.
The phase of cell nucleus division following PROMETAPHASE, in which the CHROMOSOMES line up across the equatorial plane of the SPINDLE APPARATUS prior to separation.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
Organic nitrogenous bases. Many alkaloids of medical importance occur in the animal and vegetable kingdoms, and some have been synthesized. (Grant & Hackh's Chemical Dictionary, 5th ed)
The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
The posterior filiform portion of the spermatozoon (SPERMATOZOA) that provides sperm motility.
A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called FLAGELLIN. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as CILIA but are longer in proportion to the cell bearing them and present in much smaller numbers. (From King & Stansfield, A Dictionary of Genetics, 4th ed)
Microtubule-associated proteins that are mainly expressed in neurons. Tau proteins constitute several isoforms and play an important role in the assembly of tubulin monomers into microtubules and in maintaining the cytoskeleton and axonal transport. Aggregation of specific sets of tau proteins in filamentous inclusions is the common feature of intraneuronal and glial fibrillar lesions (NEUROFIBRILLARY TANGLES; NEUROPIL THREADS) in numerous neurodegenerative disorders (ALZHEIMER DISEASE; TAUOPATHIES).
A systemic agricultural fungicide used for control of certain fungal diseases of stone fruit.
The interval between two successive CELL DIVISIONS during which the CHROMOSOMES are not individually distinguishable. It is composed of the G phases (G1 PHASE; G0 PHASE; G2 PHASE) and S PHASE (when DNA replication occurs).
Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.
Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in TELEPATHOLOGY.
The final phase of cell nucleus division following ANAPHASE, in which two daughter nuclei are formed, the CYTOPLASM completes division, and the CHROMOSOMES lose their distinctness and are transformed into CHROMATIN threads.
Specific particles of membrane-bound organized living substances present in eukaryotic cells, such as the MITOCHONDRIA; the GOLGI APPARATUS; ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.
The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS.
Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
The first phase of cell nucleus division, in which the CHROMOSOMES become visible, the CELL NUCLEUS starts to lose its identity, the SPINDLE APPARATUS appears, and the CENTRIOLES migrate toward opposite poles.
Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)
Antitumor alkaloid isolated from Vinca rosea. (Merck, 11th ed.)
Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.
Established cell cultures that have the potential to propagate indefinitely.
Cytoplasmic filaments intermediate in diameter (about 10 nanometers) between the microfilaments and the microtubules. They may be composed of any of a number of different proteins and form a ring around the cell nucleus.
A fungal metabolite that blocks cytoplasmic cleavage by blocking formation of contractile microfilament structures resulting in multinucleated cell formation, reversible inhibition of cell movement, and the induction of cellular extrusion. Additional reported effects include the inhibition of actin polymerization, DNA synthesis, sperm motility, glucose transport, thyroid secretion, and growth hormone release.
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
11- to 14-membered macrocyclic lactones with a fused isoindolone. Members with INDOLES attached at the C10 position are called chaetoglobosins. They are produced by various fungi. Some members interact with ACTIN and inhibit CYTOKINESIS.
The directed transport of ORGANELLES and molecules along nerve cell AXONS. Transport can be anterograde (from the cell body) or retrograde (toward the cell body). (Alberts et al., Molecular Biology of the Cell, 3d ed, pG3)
Benzene derivatives which are substituted with two nitro groups in the ortho, meta or para positions.
Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.
The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
A lignan (LIGNANS) found in PODOPHYLLIN resin from the roots of PODOPHYLLUM plants. It is a potent spindle poison, toxic if taken internally, and has been used as a cathartic. It is very irritating to skin and mucous membranes, has keratolytic actions, has been used to treat warts and keratoses, and may have antineoplastic properties, as do some of its congeners and derivatives.
Proteins which are involved in the phenomenon of light emission in living systems. Included are the "enzymatic" and "non-enzymatic" types of system with or without the presence of oxygen or co-factors.
The clear constricted portion of the chromosome at which the chromatids are joined and by which the chromosome is attached to the spindle during cell division.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
A family of Urodela consisting of 15 living genera and about 42 species and occurring in North America, Europe, Asia, and North Africa.
A family of highly conserved serine-threonine kinases that are involved in the regulation of MITOSIS. They are involved in many aspects of cell division, including centrosome duplication, SPINDLE APPARATUS formation, chromosome alignment, attachment to the spindle, checkpoint activation, and CYTOKINESIS.
A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.
A genus GREEN ALGAE in the order VOLVOCIDA. It consists of solitary biflagellated organisms common in fresh water and damp soil.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.
A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough ENDOPLASMIC RETICULUM and directing them to secretory vesicles, LYSOSOMES, or the CELL MEMBRANE. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Compounds with a BENZENE fused to IMIDAZOLES.
A phylum of the most familiar marine invertebrates. Its class Stelleroidea contains two subclasses, the Asteroidea (the STARFISH or sea stars) and the Ophiuroidea (the brittle stars, also called basket stars and serpent stars). There are 1500 described species of STARFISH found throughout the world. The second class, Echinoidea, contains about 950 species of SEA URCHINS, heart urchins, and sand dollars. A third class, Holothuroidea, comprises about 900 echinoderms known as SEA CUCUMBERS. Echinoderms are used extensively in biological research. (From Barnes, Invertebrate Zoology, 5th ed, pp773-826)
The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.
A cytotoxic member of the CYTOCHALASINS.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.
A mature haploid female germ cell extruded from the OVARY at OVULATION.
A ubiquitous phosphoprotein that serves as an intracellular substrate for a variety of SIGNAL TRANSDUCTION PATHWAYS. PHOSPHORYLATION of stathmin occurs during CELL CYCLE progression, and stathmin functions as a microtubule-destabilizing protein that promotes MICROTUBULE depolymerization during INTERPHASE and late MITOSIS. Stathmin is expressed at very high levels in a variety of human CANCERS.
Chemical reaction in which monomeric components are combined to form POLYMERS (e.g., POLYMETHYLMETHACRYLATE).
One of the three domains of life (the others being BACTERIA and ARCHAEA), also called Eukarya. These are organisms whose cells are enclosed in membranes and possess a nucleus. They comprise almost all multicellular and many unicellular organisms, and are traditionally divided into groups (sometimes called kingdoms) including ANIMALS; PLANTS; FUNGI; and various algae and other taxa that were previously part of the old kingdom Protista.
Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.
A bundle of MICROTUBULES and MICROTUBULE-ASSOCIATED PROTEINS forming the core of each CILIUM or FLAGELLUM. In most eukaryotic cilia or flagella, an axoneme shaft has 20 microtubules arranged in nine doublets and two singlets.
Agents that arrest cells in MITOSIS, most notably TUBULIN MODULATORS.
The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.
The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.
Male germ cells derived from SPERMATOGONIA. The euploid primary spermatocytes undergo MEIOSIS and give rise to the haploid secondary spermatocytes which in turn give rise to SPERMATIDS.
A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.
The rate dynamics in chemical or physical systems.
Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).
2-Substituted benzimidazole first introduced in 1962. It is active against a variety of nematodes and is the drug of choice for STRONGYLOIDIASIS. It has CENTRAL NERVOUS SYSTEM side effects and hepatototoxic potential. (From Smith and Reynard, Textbook of Pharmacology, 1992, p919)
A form of interference microscopy in which variations of the refracting index in the object are converted into variations of intensity in the image. This is achieved by the action of a phase plate.
5'-Adenylic acid, monoanhydride with imidodiphosphoric acid. An analog of ATP, in which the oxygen atom bridging the beta to the gamma phosphate is replaced by a nitrogen atom. It is a potent competitive inhibitor of soluble and membrane-bound mitochondrial ATPase and also inhibits ATP-dependent reactions of oxidative phosphorylation.
A family of rat kangaroos found in and around Australia. Genera include Potorous and Bettongia.
A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.
Chromatophores (large pigment cells of fish, amphibia, reptiles and many invertebrates) which contain melanin. Short term color changes are brought about by an active redistribution of the melanophores pigment containing organelles (MELANOSOMES). Mammals do not have melanophores; however they have retained smaller pigment cells known as MELANOCYTES.
Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and PHOSPHOPROTEIN PHOSPHATASES as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.
Polymers synthesized by living organisms. They play a role in the formation of macromolecular structures and are synthesized via the covalent linkage of biological molecules, especially AMINO ACIDS; NUCLEOTIDES; and CARBOHYDRATES.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
A genus of the family Heteromyidae which contains 22 species. Their physiology is adapted for the conservation of water, and they seldom drink water. They are found in arid or desert habitats and travel by hopping on their hind limbs.
Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).
A method used to study the lateral movement of MEMBRANE PROTEINS and LIPIDS. A small area of a cell membrane is bleached by laser light and the amount of time necessary for unbleached fluorescent marker-tagged proteins to diffuse back into the bleached site is a measurement of the cell membrane's fluidity. The diffusion coefficient of a protein or lipid in the membrane can be calculated from the data. (From Segen, Current Med Talk, 1995).
The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.
The movement of CYTOPLASM within a CELL. It serves as an internal transport system for moving essential substances throughout the cell, and in single-celled organisms, such as the AMOEBA, it is responsible for the movement (CELL MOVEMENT) of the entire cell.
The science and application of a double-beam transmission interference microscope in which the illuminating light beam is split into two paths. One beam passes through the specimen while the other beam reflects off a reference mirror before joining and interfering with the other. The observed optical path difference between the two beams can be measured and used to discriminate minute differences in thickness and refraction of non-stained transparent specimens, such as living cells in culture.
The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.
A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey (C. pygerythrus) is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.
Reduced (protonated) form of THIAZOLES. They can be oxidized to THIAZOLIDINEDIONES.
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
Formation of an acetyl derivative. (Stedman, 25th ed)
An absence of warmth or heat or a temperature notably below an accustomed norm.
A genus of ciliate protozoa commonly used in genetic, cytological, and other research.
Major constituent of the cytoskeleton found in the cytoplasm of eukaryotic cells. They form a flexible framework for the cell, provide attachment points for organelles and formed bodies, and make communication between parts of the cell possible.
Proteins obtained from the species Schizosaccharomyces pombe. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
Derivatives of carbamic acid, H2NC(=O)OH. Included under this heading are N-substituted and O-substituted carbamic acids. In general carbamate esters are referred to as urethanes, and polymers that include repeating units of carbamate are referred to as POLYURETHANES. Note however that polyurethanes are derived from the polymerization of ISOCYANATES and the singular term URETHANE refers to the ethyl ester of carbamic acid.
Proteins obtained from various species of Xenopus. Included here are proteins from the African clawed frog (XENOPUS LAEVIS). Many of these proteins have been the subject of scientific investigations in the area of MORPHOGENESIS and development.
An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.
A carbamate that is used as an herbicide and as a plant growth regulator.
The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)
An antifungal agent used in the treatment of TINEA infections.
An aurora kinase that is a component of the chromosomal passenger protein complex and is involved in the regulation of MITOSIS. It mediates proper CHROMOSOME SEGREGATION and contractile ring function during CYTOKINESIS.
Bulbous enlargement of the growing tip of nerve axons and dendrites. They are crucial to neuronal development because of their pathfinding ability and their role in synaptogenesis.
A broad category of nuclear proteins that are components of or participate in the formation of the NUCLEAR MATRIX.
A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)
Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.
A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.
The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.
Agents obtained from higher plants that have demonstrable cytostatic or antineoplastic activity.
The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.
CELL LINES derived from the CV-1 cell line by transformation with a replication origin defective mutant of SV40 VIRUS, which codes for wild type large T antigen (ANTIGENS, POLYOMAVIRUS TRANSFORMING). They are used for transfection and cloning. (The CV-1 cell line was derived from the kidney of an adult male African green monkey (CERCOPITHECUS AETHIOPS).)
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
Nucleoproteins, which in contrast to HISTONES, are acid insoluble. They are involved in chromosomal functions; e.g. they bind selectively to DNA, stimulate transcription resulting in tissue-specific RNA synthesis and undergo specific changes in response to various hormones or phytomitogens.
Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
Changes in the amounts of various chemicals (neurotransmitters, receptors, enzymes, and other metabolites) specific to the area of the central nervous system contained within the head. These are monitored over time, during sensory stimulation, or under different disease states.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
The quality of surface form or outline of CELLS.
A species of fruit fly much used in genetics because of the large size of its chromosomes.
A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.
A partitioning within cells due to the selectively permeable membranes which enclose each of the separate parts, e.g., mitochondria, lysosomes, etc.
A group of 16-member MACROLIDES which stabilize MICROTUBULES in a manner similar to PACLITAXEL. They were originally found in the myxobacterium Sorangium cellulosum, now renamed to Polyangium (MYXOCOCCALES).
The art, technique, or business of producing motion pictures for entertainment, propaganda, or instruction.
A family of herbivorous leaping MAMMALS of Australia, New Guinea, and adjacent islands. Members include kangaroos, wallabies, quokkas, and wallaroos.
The large pigment cells of fish, amphibia, reptiles and many invertebrates which actively disperse and aggregate their pigment granules. These cells include MELANOPHORES, erythrophores, xanthophores, leucophores and iridiophores. (In algae, chromatophores refer to CHLOROPLASTS. In phototrophic bacteria chromatophores refer to membranous organelles (BACTERIAL CHROMATOPHORES).)
A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.
The fertilized OVUM resulting from the fusion of a male and a female gamete.
Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.
A class of saturated compounds consisting of two rings only, having two or more atoms in common, containing at least one hetero atom, and that take the name of an open chain hydrocarbon containing the same total number of atoms. (From Riguady et al., Nomenclature of Organic Chemistry, 1979, p31)
A plant genus of the family LILIACEAE that contains cholestane glycosides (CHOLESTANES).

Mutations of oncoprotein 18/stathmin identify tubulin-directed regulatory activities distinct from tubulin association. (1/10496)

Oncoprotein 18/stathmin (Op18) is a recently identified phosphorylation-responsive regulator of the microtubule (MT) system. It was originally proposed that Op18 specifically regulates dynamic properties of MTs by associating with tubulin, but it has subsequently been proposed that Op18 acts simply by sequestering of tubulin heterodimers. We have dissected the mechanistic action of Op18 by generation of two distinct classes of mutants. One class has interruptions of the heptad repeats of a potential coiled-coil region of Op18, and the other involves substitution at all four phosphorylation sites with negatively charged Glu residues. Both types of mutation result in Op18 proteins with a limited decrease in tubulin complex formation. However, the MT-destabilizing activities of the coiled-coil mutants are more severely reduced in transfected leukemia cells than those of the Glu-substituted Op18 derivative, providing evidence for tubulin-directed regulatory activities distinct from tubulin complex formation. Analysis of Op18-mediated regulation of tubulin GTPase activity and taxol-promoted tubulin polymerization showed that while wild-type and Glu-substituted Op18 derivatives are active, the coiled-coil mutants are essentially inactive. This suggests that Op18-tubulin contact involves structural motifs that deliver a signal of regulatory importance to the MT system.  (+info)

A processive single-headed motor: kinesin superfamily protein KIF1A. (2/10496)

A single kinesin molecule can move "processively" along a microtubule for more than 1 micrometer before detaching from it. The prevailing explanation for this processive movement is the "walking model," which envisions that each of two motor domains (heads) of the kinesin molecule binds coordinately to the microtubule. This implies that each kinesin molecule must have two heads to "walk" and that a single-headed kinesin could not move processively. Here, a motor-domain construct of KIF1A, a single-headed kinesin superfamily protein, was shown to move processively along the microtubule for more than 1 micrometer. The movement along the microtubules was stochastic and fitted a biased Brownian-movement model.  (+info)

Vibrio parahaemolyticus thermostable direct hemolysin modulates cytoskeletal organization and calcium homeostasis in intestinal cultured cells. (3/10496)

Vibrio parahaemolyticus is a marine bacterium known to be the leading cause of seafood gastroenteritis worldwide. A 46-kDa homodimer protein secreted by this microorganism, the thermostable direct hemolysin (TDH), is considered a major virulence factor involved in bacterial pathogenesis since a high percentage of strains of clinical origin are positive for TDH production. TDH is a pore-forming toxin, and its most extensively studied effect is the ability to cause hemolysis of erythrocytes from different mammalian species. Moreover, TDH induces in a variety of cells cytotoxic effects consisting mainly of cell degeneration which often leads to loss of viability. In this work, we examined the cellular changes induced by TDH in monolayers of IEC-6 cells (derived from the rat crypt small intestine), which represent a useful cell model for studying toxins from enteric bacteria. In experimental conditions allowing cell survival, TDH induces a rapid transient increase in intracellular calcium as well as a significant though reversible decreased rate of progression through the cell cycle. The morphological changes seem to be dependent on the organization of the microtubular network, which appears to be the preferential cytoskeletal element involved in the cellular response to the toxin.  (+info)

Gibberellic acid stabilises microtubules in maize suspension cells to cold and stimulates acetylation of alpha-tubulin. (4/10496)

Gibberellic acid is known to stabilise microtubules in plant organs against depolymerisation. We have now devised a simplified cell system for studying this. Pretreatment of a maize cell suspension with gibberellic acid for just 3 h stabilised protoplast microtubules against depolymerisation on ice. In other eukaryotes, acetylation of alpha-tubulin is known to correlate with microtubule stabilisation but this is not established in plants. By isolating the polymeric tubulin fraction from maize cytoskeletons and immunoblotting with the antibody 6-11B-1, we have demonstrated that gibberellic acid stimulates the acetylation of alpha-tubulin. This is the first demonstrated link between microtubule stabilisation and tubulin acetylation in higher plants.  (+info)

Evidence for a correlation between the number of marginal band microtubules and the size of vertebrate erthrocytes. (5/10496)

In 23 species of vertebrates the dimensions of erythrocytes and the number of their marginal band microtubules were examined. A positive correlation was found between the size of erythrocytes and the number of microtubules. The absence of microtubules in diskoid erythrocytes of mammals-Camelidae-is discussed.  (+info)

The preprophase band: possible involvement in the formation of the cell wall. (6/10496)

Numerous vesicles were observed among the microtubules of the "preprophase" band in prophase cells from root tips of Allium cepa. The content of these vesicles looks similar to the matrix of adjacent cell walls, and these vesicles often appear to be involved in exocytosis. In addition, the cell walls perpendicular to the plane of (beneath) the preprophase band are often differentially thickened compared to the walls lying parallel to the plane of the band. Our interpretation of these observations is that the preprophase band may direct or channel vesicles containing precursors of the cell wall to localized regions of wall synthesis. The incorporation of constituents of the cell wall into a narrow region defined by the position of the preprophase band may be a mechanism that ensures unidirecitonal growth of meristematic cells.  (+info)

EB1, a protein which interacts with the APC tumour suppressor, is associated with the microtubule cytoskeleton throughout the cell cycle. (7/10496)

The characteristics of the adenomatous polyposis coli (APC) associated protein EB1 were examined in mammalian cells. By immunocytochemistry EB1 was shown to be closely associated with the microtubule cytoskeleton throughout the cell cycle. In interphase cells EB1 was associated with microtubules along their full length but was often particularly concentrated at their tips. During early mitosis, EB1 was localized to separating centrosomes and associated microtubules, while at metaphase it was associated with the spindle poles and associated microtubules. During cytokinesis EB1 was strongly associated with the midbody microtubules. Treatment with nocodazole caused a diffuse redistribution of EB1 immunoreactivity, whereas treatment with cytochalasin D had no effect. Interestingly, treatment with taxol abolished the EB1 association with microtubules. In nocodazole washout experiments EB1 rapidly became associated with the centrosome and repolymerizing microtubules. In taxol wash-out experiments EB1 rapidly re-associated with the microtubule cytoskeleton, resembling untreated control cells within 10 min. Immunostaining of SW480 cells, which contain truncated APC incapable of interaction with EB1, showed that the association of EB1 with microtubules throughout the cell cycle was not dependent upon an interaction with APC. These results suggest a role for EB1 in the control of microtubule dynamics in mammalian cells.  (+info)

Opposing motor activities of dynein and kinesin determine retention and transport of MHC class II-containing compartments. (8/10496)

MHC class II molecules exert their function at the cell surface by presenting to T cells antigenic fragments that are generated in the endosomal pathway. The class II molecules are targetted to early lysosomal structures, termed MIIC, where they interact with antigenic fragments and are subsequently transported to the cell surface. We previously visualised vesicular transport of MHC class II-containing early lysosomes from the microtubule organising centre (MTOC) region towards the cell surface in living cells. Here we show that the MIIC move bidirectionally in a 'stop-and-go' fashion. Overexpression of a motor head-deleted kinesin inhibited MIIC motility, showing that kinesin is the motor that drives its plus end transport towards the cell periphery. Cytoplasmic dynein mediates the return of vesicles to the MTOC area and effectively retains the vesicles at this location, as assessed by inactivation of dynein by overexpression of dynamitin. Our data suggest a retention mechanism that determines the perinuclear accumulation of MIIC, which is the result of dynein activity being superior over kinesin activity. The bidirectional nature of MIIC movement is the result of both kinesin and dynein acting reciprocally on the MIIC during its transport. The motors may be the ultimate targets of regulatory kinases since the protein kinase inhibitor staurosporine induces a massive release of lysosomal vesicles from the MTOC region that is morphologically similar to that observed after inactivation of the dynein motor.  (+info)

Unlike cold or allergy sinus is taken as clinical, you may not be on a combination schedule. If you are prohibited the colchicine effect on microtubules regularly, take the bad dose as powerful as you remember. Skip the. Pseudoephedrine is a decongestant that works blood vessels in the expiration passages. Dilated pipe ee FED rin. Brand: Alavert D, Claritin-D, Claritin-D 24 Hour, Leader Allergy Discard D, Loratadine-D 12 Hour, Loratadine-D 24 Hour Taking colchicine effect on microtubules products together can give you to get too much of a person drug. Can you take sudafed and claritin together [While] Claritin D SudafedNyquil, can I take sumatriptan for bad yesterday headache. Colchicine interacts with tubulin and perturbs the assembly dynamics of microtubules. Microtubules, the key components of cytoskeleton are made up of a,b-tubulin heterodimers. In eukaryotic cells, they organize to form stable interphase microtubule network and highly dynamic mitotic spindle. Microtubules. Mechanism of ...
TY - JOUR. T1 - Organization of non-centrosomal microtubules in epithelial cells. AU - Toya, Mika. AU - Takeichi, Masatoshi. PY - 2016/1/1. Y1 - 2016/1/1. N2 - Polarized epithelial cells contain a characteristic array of microtubules in which non-centrosomal microtubules are aligned along the apical-to-basal axis of the cell with their minus ends oriented towards the apical pole. Although this unique orientation of microtubules was discovered in the late 1980s, how this orientation is established remains unresolved partly because of limited information about molecular factors that regulate the minus ends of non-centrosomal microtubules. Recent studies, however, identified novel minus end- associated proteins, revealing mechanisms by which the polarized arrays of microtubules are established in epithelial cells. These studies have also demonstrated the importance of apico-basally orientated microtubules in intra-structural organization of cells. This review focuses on recent progress of our ...
Serial sections of mitotic spindles of the marine cryptophycean alga, Cryptomonas, were analysed to determine what types of microtubules they contained and which of these microtubules came close enough to each other (50 nm or less) for the commonly described crossbridging to be possible. Interpolar microtubules were rare (less than or equal to 1%) but from prometaphase through anaphase there was a substantial interpolar framework of free and polar microtubules which came close enough to one another to cross-bridge and generate anaphase spindle elongation by intermicrotubule sliding. However, such elongation would also require some concomitant polar microtubule polymerization. In contrast, only about 12% of the chromosomal microtubules came within bridging distance of interpolar framework microtubules. Thus, assuming that microtubules were accurately fixed in their in vivo positions, crossbridging between chromosomal and interpolar framework microtubules is unlikely to function in ...
There is controversy concerning the source of new microtubules required for the development of neuronal axons. We have proposed that microtubules are released from the centrosome within the cell body of the neuron and are then translocated into the axon to support its growth. To investigate this possibility, we have developed an experimental regime that permits us to determine the fate of a small population of microtubules nucleated at the neuronal centrosome. Microtubules within cultured sympathetic neurons were depolymerized with the anti-microtubule drug nocodazole, after which the drug was removed. Microtubules rapidly and specifically reassembled from the centrosome within three minutes of nocodazole removal. At this point, low levels of vinblastine, another anti-microtubule drug, were added to the culture to inhibit further microtubule assembly while not substantially depolymerizing the small population of microtubules that had already assembled at the centrosome. Within minutes, released ...
Centrosomes spit out microtubules to thin out their load at the end of mitosis, as illustrated by Rusan and Wadsworth on page 21. This reorganization helps reestablish the interphase microtubule array and may contribute to localizing the cytokinetic ring.. Centrosomes nucleate many more microtubules during mitosis than they do in interphase. The new results show that the extra load is lightened in mammalian cells at late anaphase, when microtubules were released both individually and in clusters. The clusters carried with them centrosomal proteins such as γ-tubulin, the microtubule nucleator. The release of microtubules is prevented by CDK activity, as nondegradable cyclin B inhibited the disassembly after chromosome separation.. Microtubules were released and actively transported outwards in the direction of the cell poles (away from the chromosomes), where microtubules were previously scarce. Because the freed microtubules are not protected at their minus ends, they are more dynamic and turn ...
The nucleus in the yeast Saccharomyces cerevisiae migrates to distinct regions within the cell during different phases of the life cycle, mating, and mitosis. Each type of nuclear migration is dependent upon cytoplasmic microtubules. The cytoplasmic microtubules are attached to the nucleus at the spindle pole body (SPB),1 the microtubule organizing center in yeast. The SPB is embedded in the nuclear envelope, which remains intact at all stages of the yeast life cycle (Byers, 1981).. In preparation for mating, the yeast cell arrests in G1 and forms a projection-called a shmoo projection-in response to mating pheromone. The nucleus moves to the base of the shmoo neck and the cytoplasmic microtubules extend from the SPB to the tip of the shmoo (Byers and Goetsch, 1974; Rose and Fink, 1987; Read et al., 1992). Two shmoos of opposite mating type fuse to form a zygote and the intervening cell walls break down (Byers and Goetsch, 1975). The cytoplasmic microtubules can then interdigitate, and the ...
The mechanism by which EML4 stabilizes microtubules in cells, either directly or indirectly, also remains enigmatic. However, EML4 shares many features with the ch-TOG (XMAP215) family of MAPs in that both proteins have separable domains for binding the microtubule lattice and soluble tubulin. ch-TOG acts as a processive microtubule polymerase by binding to the microtubule with a basic region and then using its multiple TOG domains to add soluble tubulin to the growing microtubule plus-ends (40, 41). However, although EML4 has a basic NTD that binds the microtubule polymer and a TAPE domain that binds soluble tubulin, there was no detectable concentration of EML4 at plus ends of microtubules where it could promote growth through acting as a microtubule polymerase. Similar to tau, EML4 is abundant in the nervous system, suggesting that it may have a major function in stabilizing the long microtubules present in neurons (11). At the molecular level, proteins of the tau family bind to more than one ...
Neurons are the signaling cells of the nervous system. To propagate signals, neurons elongate several neurites, which differentiate into a single axon and several dendrites during development. Among the factors that contribute to this differentiation process, the cytoskeleton and in particular the microtubules play a key role. For instance, the growth of the axon and the dendrites depends on dynamic microtubules and requires the formation of new microtubules. The centrosome is regarded as the primary source of microtubules in axonal and dendritic growth and has been proposed to direct axon formation. However, while microtubule nucleation from centrosomes enables efficient spindle-pole organization and cytokinesis during cell division, it is difficult to reconcile the distinct microtubule array in branching axons, dendrites and spines with such focal microtubule assembly. Thus, the exact role of the centrosome and centrosomal microtubule nucleation in axon growth is still unclear. To address this ...
An ultracapacitor (2200) comprising a first electrode (2110) containing mineral microtubules, a second electrode (2210) containing mineral microtubules, an electrolyte (2030) disposed between the first electrode (2110) and the second electrode (2210), and a separator (2040) disposed in the electrolyte to provide electrical insulation between the first electrode (2110) and the second electrode (2210), while allowing ion flow within the electrolyte (2030). The electrodes may be formed from a paste containing mineral microtubules, or may consist essentially of a conductive polymer containing mineral microtubules, or an aerogel containing the mineral microtubules. The mineral microtubules may be filled with carbon, a pseudocapacitance material, or a magnetoresistive material. The mineral microtubules may also be coated with a photoconductive material.
Microtubule-dependent transport of Ad2 to the MTOC/nuclear envelope. (A) TR-labeled Ad2 was bound to HeLa cells in the cold and internalized for 15 (panel a)
Author: Wacker-Schröder, Irene et al.; Genre: Journal Article; Published in Print: 1997-07-01; Title: Microtubule-dependent transport of secretory vesicles visualized in real time with a GFP-tagged secretory protein
The tubulin monomers of brain microtubules reassembled in vitro are arranged on a 3-start helix, irrespective of whether the number of protofilaments is 13 or 14. The dimer packing is that of the B-lattice described for flagellar microtubules. This implies that the tubulin core of microtubules contains at least one helical discontinuity. Neither 5-start nor 8-start helices have a physical significance and thus cannot be implicated in models of microtubule elongation, but the structure is compatible with elongation of protofilaments by dimers or protofilamentous oligomers. The inner and outer surfaces of the microtubule wall can be visualized by propane jet freezing, freeze fracturing, and metal replication, at a resolution of at least 4 nm. The 3-start helix is left-handed, in contrast to a previous study based on negative staining and shadowing. The reasons for this discrepancy are discussed. ...
Biology Assignment Help, Describe microtubular cytoskeleton in protozoans, Protozoans have endoskeletons formed from microtubular cytoskeleton of the exoskeletons or cytoplasm secreted as shells or tests. Some of these single-cell organisms are capable of defending themselves by using organelles like trichocysts, and others
Microtubules are biopolymers consisting of tubulin dimer subunits. As a major component of cytoskeleton they are essential for supporting most important cellular processes such as cell division, signaling, intracellular transport and cell locomotion. The hydrolysis of guanosine triphosphate (GTP) molecules attached to each tubulin subunit supports the nonequilibrium nature of microtubule dynamics. One of the most spectacular properties of microtubules is their dynamic instability when their growth from continuous attachment of tubulin dimers stochastically alternates with periods of shrinking. Despite the critical importance of this process to all cellular activities, its mechanism remains not fully understood. We investigated theoretically microtubule dynamics at all times by analyzing explicitly temporal evolution of various length clusters of unhydrolyzed subunits. It is found that the dynamic behavior of microtubules depends strongly on initial conditions. Our theoretical findings provide a ...
The microtubules are intracellular dynamic polymers made up of evolutionarily conserved polymorphic alpha/beta-tubulin heterodimers and a large number of microtubule-associated proteins (MAPs). The microtubules consist of 13 protofilaments and have an outer diameter 25 nm. Microtubules have their intrinsic polarity; highly dynamic plus ends and less dynamic minus ends. Microtubules are required for vital processes in eukaryotic cells including mitosis, meiosis, maintenance of cell shape and intracellular transport. Microtubules are also necessary for movement of cells by means of flagella and cilia. In mammalian tissue culture cells microtubules have their minus ends anchored in microtubule organizing centers (MTOCs). The GTP (guanosintriphosphate) molecule is an essential for tubulin heterodimer to associate with other heterodimers to form microtubule. In vivo, microtubule dynamics vary considerably. Microtubule polymerization is reversible and a populations of microtubules in cells are on ...
An organized microtubule array is essential for the polarized motility of fibroblasts. Dynamic microtubules closely interact with focal adhesion sites in migrating cells. Here, we examined the effect of focal adhesions on microtubule dynamics. We observed that the probability of microtubule catastrophes (transitions from growth to shrinkage) was seven times higher at focal adhesions than elsewhere. Analysis of the dependence between the microtubule growth rate and catastrophe probability throughout the cytoplasm revealed that a nonspecific (mechanical or spatial) factor provided a minor contribution to the catastrophe induction by decreasing microtubule growth rate at adhesions. Strikingly, at the same growth rate, the probability of catastrophes was significantly higher at adhesions than elsewhere, indicative of a site-specific biochemical trigger. The observed catastrophe induction occurred at adhesion domains containing the scaffolding protein paxillin that has been shown previously to ...
Microtubules - cellular highways that deliver cargo to the cell membrane for secretion - have a surprising role in pancreatic beta cells. Instead of facilitating glucose-stimulated insulin secretion, they limit it, a team of Vanderbilt investigators reported recently in Developmental Cell.. The findings reveal that microtubules act as a cellular rheostat to precisely control insulin secretion and suggest that disturbance of this control may contribute to beta cell dysfunction and type 2 diabetes. Targeting the microtubule regulation of insulin secretion may offer new ways to treat diabetes.. Irina Kaverina, Ph.D., Xiadong Zhu, Ph.D., and colleagues began using pancreatic beta cells as a model to study microtubule function - to explore how microtubules traffic cargo such as insulin granules from the cell interior to the periphery.. In their initial studies, the researchers used compounds to destroy the microtubules, then stimulated the pancreatic islets with glucose and measured how much ...
Integrin-linked kinase (ILK) localizes to both focal adhesions and centrosomes in distinct multiprotein complexes. Its dual function as a kinase and scaffolding protein has been well characterized at focal adhesions, where it regulates integrin-mediated cell adhesion, spreading, migration and signaling. At the centrosomes, ILK regulates mitotic spindle organization and centrosome clustering. Our previous study showed various spindle defects after ILK knockdown or inhibition that suggested alteration in microtubule dynamics. Since ILK expression is frequently elevated in many cancer types, we investigated the effects of ILK overexpression on microtubule dynamics. We show here that overexpressing ILK in HeLa cells was associated with a shorter duration of mitosis and decreased sensitivity to paclitaxel, a chemotherapeutic agent that suppresses microtubule dynamics. Measurement of interphase microtubule dynamics revealed that ILK overexpression favored microtubule depolymerization, suggesting that ...
Controlling microtubule dynamics and spatial organization is a fundamental requirement of eukaryotic cell function. Members of the ORBIT/MAST/CLASP family of microtubule-associated proteins associate with the plus ends of microtubules, where they promote the addition of tubulin subunits into attached kinetochore fibers during mitosis and stabilize microtubules in the vicinity of the plasma membrane during interphase. To date, nothing is known about their function in plants. Here, we show that the Arabidopsis thaliana CLASP protein is a microtubule-associated protein that is involved in both cell division and cell expansion. Green fluorescent protein-CLASP localizes along the full length of microtubules and shows enrichment at growing plus ends. Our analysis suggests that CLASP promotes microtubule stability. clasp-1 T-DNA insertion mutants are hypersensitive to microtubule-destabilizing drugs and exhibit more sparsely populated, yet well ordered, root cortical microtubule arrays. Overexpression ...
The microtubules are intracellular dynamic polymers made up of evolutionarily conserved polymorphic alpha/beta-tubulin heterodimers and a large number of microtubule-associated proteins (MAPs). The microtubules consist of 13 protofilaments and have an outer diameter 25 nm. Microtubules have their intrinsic polarity; highly dynamic plus ends and less dynamic minus ends. Microtubules are required for vital processes in eukaryotic cells including mitosis, meiosis, maintenance of cell shape and intracellular transport. Microtubules are also necessary for movement of cells by means of flagella and cilia. In mammalian tissue culture cells microtubules have their minus ends anchored in microtubule organizing centers (MTOCs). The GTP (guanosintriphosphate) molecule is an essential for tubulin heterodimer to associate with other heterodimers to form microtubule. In vivo, microtubule dynamics vary considerably. Microtubule polymerization is reversible and a populations of microtubules in cells are on ...
EB1 was identified by its ability to interact with APC, a tumor suppressor protein that has been shown to associate with microtubules and promote microtubule assembly in vitro (15). We have examined the subcellular distribution of EB1 by indirect immunofluorescence and confocal microscopy, using mAbs specific for EB1. Our results indicate that EB1 decorates the centrosome and the microtubule cytoskeleton throughout the cell cycle.. Previous studies performed on RKO, a human colorectal cancer cell line, and the mouse fibroblast cell line NIH 3T3 have shown that overexpressed full-length, but not truncated, APC associated to microtubules (11). We analyzed the subcellular distribution of EB1 in SW480, a colon cancer cell line that expresses a carboxyl-terminal deleted form of APC that is unable to interact with either EB1 or microtubules; in these cells EB1 localization to microtubules and the centrosome was preserved (Fig. 1d), demonstrating that the cellular distribution of EB1 does not depend on ...
Microtubules play a central role in cell division and cell polarity in eukaryotic cells. Fission yeast represents a useful model system for studies of their regulation, since its cytoskeleton is highly organized and dynamic. Interphase fission yeast cells contain 2-5 longitudinal bundles of microtubules, and these grow from the cell centre to its ends, where they undergo catastrophe. Mercedes Pardo and Paul Nurse have now characterized Amo1, a nucleoporin-like protein whose overexpression causes microtubules to bundle on one side of the cell (see p. 1705). Amo1 localizes to the nuclear rim but does not overlap with nuclear pore complex components. The phenotype of amo1Δ cells indicates that Amo1 helps to regulate microtubule growth, cell-end termination and cell polarity. These observations, together with the localization of Amo1, suggest that the interplay between the nucleus and microtubules is important for the regulation of microtubule dynamics. However, Pardo and Nurse find no evidence ...
During mitosis, two arrays of microtubules form the bipolar mitotic spindle in order to effect partitioning of the duplicated chromosomes into the daughter cells. The fabrication of the spindle therefore is a key step in successful cell division, and a protein known as NuMA is needed to properly gather the ends of the microtubules at the poles.. Merdes et al. have found that, at the onset of mitosis, a complex of the microtubule motor protein dynein and dynactin powers NuMA transport along microtubules to the polar region. Transport and continued localization of NuMA at the pole is required to form and maintain an intact spindle, perhaps through binding of the individual microtubules to a NuMA multimer. Disruption of NuMA transport by addition of the dynactin inhibitor dynamitin, or by addition of anti-dynein antibodies, releases spindle microtubules from the tightly focused poles.-SMH. J. Cell Biol.149, 851 (2000).. ...
Here, we report that a centrosomal protein FOR20 [FOP (FGFR1 (fibroblast growth factor receptor 1) oncogene protein)-like protein of molecular mass of 20 kDa; also named as C16orf63, FLJ31153 or PHSECRG2] can regulate the assembly and stability of microtubules. Both FOR20 IgG antibody and GST (glutathione S-transferase)-tagged FOR20 could precipitate tubulin from the HeLa cell extract, indicating a possible interaction between FOR20 and tubulin. FOR20 was also detected in goat brain tissue extract and it cycled with microtubule-associated proteins. Furthermore, FOR20 bound to purified tubulin and inhibited the assembly of tubulin in vitro. The overexpression of FOR20 depolymerized interphase microtubules and the depletion of FOR20 prevented nocodazole-induced depolymerization of microtubules in HeLa cells. In addition, the depletion of FOR20 suppressed the dynamics of individual microtubules in live HeLa cells. FOR20-depleted MDA-MB-231 cells displayed zigzag motion and migrated at a slower rate ...
Microtubules (MTs) are polymers of α/β-tubulin heterodimers that self-assemble into polar filaments with a fast-growing end, the plus end, and a relatively stable end, the minus end [1]. MTs play diverse roles at all stages of the eukaryotic cell cycle; guiding cell division, expansion and morphogenesis. To accomplish their varied tasks, MTs group together to form specialized arrays that are continuously remodeled by a process termed dynamic instability, wherein individual MT ends switch stochastically between growth and shrinkage through GTP hydrolysis [1, 2]. Transitions from growth to shrinkage are termed catastrophe, and the transitions from shrinkage to growth are called rescue [3]. These parameters are biochemically modulated by MT-associated proteins (MAPs), which perform a variety of functions including stabilizing MTs through promoting polymerization of tubulin [4, 5], facilitating MT-MT interactions (e.g. crosslinking) [6, 7], and destabilizing MTs through increasing depolymerisation ...
Microtubules are one of three cytoskeletal filaments found in eukaryotic cells, which exhibit a constant transition between growth and shrinkage states. This phenomenon, known as dynamic instability, is the focus of our study. We have investigated microtubule dynamics found in isotypically purified β-tubulin in order to understand how different microtubule protein compositions may affect growth and shrinkage rates. A deeper understanding of these dynamics allows us to calculate nanoscale mechanical properties of microtubules such as their force generation and rigidity. In this paper we analyze the differences between the polymerization and depolymerization rates of purified β-II, β-III, and β-IV microtubules. Each of these three isotypes displays varying behavior in terms of dynamic instability rates. We developed a model that describes the different growth and shrinkage behavior of each isotype in terms of a recursive map representation based on a modified random walk with four independent ...
Reorganization of the oocyte microtubule cytoskeleton during mid-oogenesis results in an apparent AP gradient of microtubules (Theurkauf et al., 1992). A longstanding model proposed that these microtubules are polarized along the AP axis, with minus ends nucleated at the anterior cortex and plus ends projected towards the posterior. Accordingly, whether an RNP particle is transported to the anterior or posterior pole would depend on whether it associates with dynein or kinesin motor proteins. This model is based on a number of observations. First, partial microtubule depolymerization leaves short microtubules associated with the anterior cortex (Theurkauf et al., 1992). Because microtubules depolymerize from the plus end, this result suggests that microtubules are nucleated at the anterior cortex. Furthermore, a fusion between the motor domain of kinesin and β-galactosidase (kinesin-β-gal) that localizes to the plus ends of microtubules in neurons (Giniger et al., 1993) accumulates at the ...
The taccalonolides are highly acetylated steroids that stabilize cellular microtubules and overcome multiple mechanisms of taxane resistance. Recently, two potent taccalonolides, AF and AJ, were identified that bind to tubulin directly and enhance microtubule polymerization. Extensive studies were conducted to characterize these new taccalonolides. AF and AJ caused aberrant mitotic spindles and bundling of interphase microtubules that differed from the effects of either paclitaxel or laulimalide. AJ also distinctly affected microtubule polymerization in that it enhanced the rate and extent of polymerization in the absence of any noticeable effect on microtubule nucleation. In addition, the resulting microtubules were found to be profoundly cold stable. These data, along with studies showing synergistic antiproliferative effects between AJ and either paclitaxel or laulimalide, suggest a distinct binding site. Direct binding studies demonstrated that AJ could not be displaced from microtubules by ...
Protein microtubules organize space, support morphology and guide molecular motors in all eukaryotic cells. These roles are mission-critical for cell division. Evolution has, accordingly, tightly constrained microtubules. They exhibit a high degree of homology across all eukaryotic organisms, from yeast to human. Being thus a relatively primitive example of biomolecular machinery, microtubules are an excellent target for mimicry via de novo design. In addition, many well-studied aspects of microtubules, such as their stiffness, stability, and dynamics of assembly, offer quantitative metrics for assessing mimics and testing models that motivate their design. I will describe our recent and ongoing efforts to build microtubules out of DNA and discuss the implications for improved understanding of biological design and enhanced capability in DNA nanotechnology. ...
Knowles, CL and Koutoulis, A and Reid, JB (2004) Microtubule Orientation in the Brassinosteroid Mutants lk, lka and lkb of Pea. Journal of Plant Growth Regulation, 23. pp. 146-155. ISSN 0721-7595 ...
Imaging the Neuronal Microtubule Cytoskeleton Microtubules are essential cytoskeletal components of neurons. They are fundamental to many neuronal processes, such as long-distance transport, but they also establish and maintain neuronal morphology. We are interested in dynamic as well as structural parameters of the microtubule cytoskeleton, such as microtubule number, length, distribution, orientation, and bundling throughout neuronal differentiation. The aim of this imaging-based project is to resolve the spatial organization of the microtubule cytoskeleton throughout neuronal differentiation with nanometer precision. Individuals experienced / interested in neurobiology, biophysics, biochemistry or bioengineering are invited to apply. Please send a CV, a letter of motivation, and names of up to 3 references via email to [email protected] and [email protected] Keywords: Microtubule cytoskeleton, neuronal differentiation, superresolution microscopy, nanobodies, ...
TY - JOUR. T1 - The leading role of microtubules in endothelial barrier dysfunction. T2 - Disassembly of peripheral microtubules leaves behind the cytoskeletal reorganization. AU - Alieva, Irina B.. AU - Zemskov, Evgeny A.. AU - Smurova, Ksenija M.. AU - Kaverina, Irina N.. AU - Verin, Alexander D.. PY - 2013/10. Y1 - 2013/10. N2 - Disturbance of the endothelial barrier is characterized by dramatic cytoskeleton reorganization, activation of actomyosin contraction and, finally, leads to intercellular gap formation. Here we demonstrate that the edemagenic agent, thrombin, causes a rapid increase in the human pulmonary artery endothelial cell (EC) barrier permeability accompanied by fast decreasing in the peripheral microtubules quantity and reorganization of the microtubule system in the internal cytoplasm of the EC within 5 min of the treatment. The actin stress-fibers formation occurs gradually and the maximal effect is observed relatively later, 30 min of the thrombin treatment. Thus, ...
In a dividing eukaryotic cell, proper chromosome segregation requires the dynamic yet persistent attachment of kinetochores to spindle microtubules. In the budding yeast Saccharomyces cerevisiae, this function is especially crucial because each kinetochore is attached to a single microtubule; consequently, loss of attachment could lead to unrecoverable chromosome loss. The highly specialized heterodecameric Dam1 protein complex achieves this coupling by assembling into a microtubule-encircling ring that glides near the end of the dynamic microtubule to mediate chromosome motion. In recent years, we have learned a great deal about the structural properties of the Dam1 heterodecamer, its mechanism of self-assembly into rings, and its tethering to the kinetochore by the elongated Ndc80 complex. The most remarkable progress has resulted from defining the fine structures of helical bundles within Dam1 heterodecamer. In this review, we critically analyze structural observations collected by diverse ...
Many different cell types possess microtubule patterns which appear to be polarized and oriented, in part, by cytoplasmic factors not directly associated with a centrosome. Recently, we demonstrated that cytoplasmic extensions (arms) of teleost melanophores will reorganize their microtubule population outward from their centers after surgical isolation (McNiven, M. A., M. Wang, and K. R. Porter. 1984. Cell. 37:753-765). In the study reported here, we examine microtubule dynamics within the centrosome-free fragments and find that, after severing, microtubule reorganization is initiated at the proximal (cut) end of an arm and migrates distally with the aggregated pigment mass until it becomes permanently positioned at the middle of the arm. Computer-aided image analysis demonstrates that this middle position is located at the arm centroid, implicating the action of a cytoplasmic gel in this process. Morphological studies of arms devoid of pigment reveal that microtubules do not emanate from a ...
Microtubules (MTs) are filamentous structures found throughout the cytoplasm of eukaryotic cells. They are polymers of tubulin that are involved in maintaining the structural integrity and plasticity of cells as well as the internal structures of cilia and flagella. Microtubules are also essential in several key cellular processes such as cell division and intracellular transport.. Proteins that accumulate at the ends of growing microtubules, known as MT plus end-tracking proteins, play an important role in regulating the dynamics and organization of the organelle. The SLAIN2 gene encodes one such MT plus end-tracking protein. This protein is targeted to microtubule tips by interacting with End-Binding proteins through its C-terminal domain. It is involved in cytoplasmic microtubule organization and nucleation. Through its N-terminal domain, it binds with the polymerase ch-TOG, recruiting it to the microtubule plus ends and thus ensuring microtubule elongation. ...
We constructed complexes between isolated chromosomes and microtubules made from purified tubulin to study the movement of chromosomes towards the minus end of microtubules in vitro, a process analogous to the movement of chromosomes towards the pole of the spindle at anaphase of mitosis. Our results show that the energy for this movement is derived solely from microtubule depolymerization, and indicate that anaphase movement of chromosomes is both powered and regulated by microtubule depolymerization at the kinetochore ...
Although assembly of the mitotic spindle is known to be a precisely controlled process, regulation of the key motor proteins involved remains poorly understood. In eukaryotes, homotetrameric kinesin-5 motors are required for bipolar spindle formation. Eg5, the vertebrate kinesin-5, has two modes of motion: an adenosine triphosphate (ATP)-dependent directional mode and a diffusive mode that does not require ATP hydrolysis. We use single-molecule experiments to examine how the switching between these modes is controlled. We find that Eg5 diffuses along individual microtubules without detectable directional bias at close to physiological ionic strength. Eg5s motility becomes directional when bound between two microtubules. Such activation through binding cargo, which, for Eg5, is a second microtubule, is analogous to known mechanisms for other kinesins. In the spindle, this might allow Eg5 to diffuse on single microtubules without hydrolyzing ATP until the motor is activated by binding to another ...
Key microtubule-organizing protein that specifically binds the minus-end of non-centrosomal microtubules and regulates their dynamics and organization. Specifically recognizes growing microtubule minus-ends and stabilizes microtubules. Acts on free microtubule minus-ends that are not capped by microtubule-nucleating proteins or other factors and protects microtubule minus-ends from depolymerization. In contrast to CAMSAP2 and CAMSAP3, tracks along the growing tips of minus-end microtubules without significantly affecting the polymerization rate: binds at the very tip of the microtubules minus-end and acts as a minus-end tracking protein (-TIP) that dissociates from microtubules after allowing tubulin incorporation. Through interaction with spectrin may regulate neurite outgrowth.
NF-kappa B, a master regulator of several signaling cascades, is known to be actively transported in the nucleus in response to various stimuli. Here, we found that NF-kappa B is associated with polymeric tubulin and co-localized with microtubules in MCF-7 cells. Using TN16, a known microtubule targeting agent, we found that microtubule dynamics plays a critical role in NF-kappa B-microtubule interaction. Treatment of cells with low concentrations of TN16 (25 and 50 nM) that suppressed microtubule dynamics without visibly affecting microtubule organization enhanced the association of NF-kappa B with microtubules and facilitated nuclear translocation of NF-kappa B. Colchicine and vinblastine also produced similar nuclear translocation of NF-kappa B. Further, nuclear import of NF-kappa B activated apoptotic pathway in the cells that were blocked in mitosis by TN16 treatment suggesting that NF-kappa B acts as a pro-apoptotic protein in response to the suppression of microtubule dynamics. ...
5 September 2013 14:00 in CM101. Microtubule assembly and disassembly is vital for many fundamental cellular processes. Our current understanding of microtubule assembly kinetics is based on a one-dimensional assembly model, which assumes that each protofilament of a microtubule behaves independently. In this model, the subunit disassociation rate from a microtubule tip is independent of free subunit concentration. Using Total-Internal-Reflection-Fluorescence (TIRF) microscopy and a laser tweezers assay to measure in vitro microtubule assembly with nanometer resolution accuracy, we now find that the subunit dissociation rate from a microtubule tip increases at higher free subunit concentrations. This is because there is a shift in microtubule tip structure from relatively blunt at low free concentrations to relatively tapered at high free concentrations, which we confirmed experimentally by TIRF microscopy. Because both the association and the dissociation rates increase at higher free subunit ...
Microtubule polarity. Illustration showing the polarity of microtubules (green) in a non-dividing cell. Microtubules are part of a cells cytoskeleton, providing internal support. The microtubules originate from a production or nucleation site (here a centrosome, red). The ends of the microtubules at this site are negatively charged. The other ends, near the plasma membrane surface of the cell, are positively charged. The cell nucleus (round, blue) is also shown. This illustration is based on a fibroblast cell. For this artwork with labels, see image C023/8762. - Stock Image C023/8763
Guard cells of stomata are characterized by ordered bundles of microtubules radiating from the ventral side toward the dorsal side of the cylindrical cell. It was suggested that microtubules play a role in directing the radial arrangement of the cellulose micro-fibrils of guard cells. However, the role of microtubules in daily cycles of opening and closing of stomata is not clear. The organization of microtubules in guard cells of Commelina communis leaves was studied by analysis of three-dimensional immunofluorescent images. It was found that while guard cell microtubules in the epidermis of leaves incubated in the light were organized in parallel, straight and dense bundles, in the dark they were less straight and oriented randomly near the stomatal pore. The effect of blue and red light on the organization of guard cell microtubules resembled the effects of white light and dark respectively. When stomata were induced to open in the dark with fusicoccin, microtubules remained in the dark ...
TY - JOUR. T1 - Microtubule-associated proteins and microtubule-based translocators have different binding sites on tubulin molecule. AU - Rodionov, V. I.. AU - Gyoeva, F. K.. AU - Kashina, A. S.. AU - Kuznetsov, S. A.. AU - Gelfand, V. I.. PY - 1990/4/25. Y1 - 1990/4/25. N2 - It has been previously shown that a class of microtubule proteins, the so-called microtubule-associated proteins (MAPs), binds to the C-terminal part of tubulin subunits. We show here that microtubules composed of tubulin whose 4-kDa C-terminal domain was cleaved by subtilisin (S-microtubules) are unable to bind MAPs but can still bind the anterograde translocator protein kinesin and the retrograde translocator dynein. Binding of both motors to S-microtubules, like their binding to normal microtubules, was ATP-dependent. In addition, direct competition experiments showed that binding sites for kinesin and MAPs on the microtubule surface lattice do not overlap. Furthermore, S-microtubules stimulated the ATPase activity of ...
The effects of free drug and tubulin-drug complexes on steady-state GTP/GDP-associated microtubules and on equilibrium guanosine 5-[beta,gamma-imido]triphosphate-associated microtubules are compared. The addition of colchicine or the tubulin-colchicine complex (TuCol) to steady-state microtubules induces microtubule disassembly. Only limited disassembly of equilibrium microtubules is observed under similar conditions. Addition of colchicine or the bifunctional colchicine analogue 2-methoxy-5-(2,3 ,4-trimethoxyphenyl) tropone to preassembled steady-state or equilibrium microtubules does induce disassembly, but establishment of the new steady state or equilibrium is very slow. These observations are related to the fact that TuCol readily adds to the microtubule end, but is only incorporated into the lattice with difficulty. As a result, microtubule growth is effectively inhibited and the critical concentration is significantly increased. Nevertheless, drug-induced disassembly can be extremely ...
A Detailed, Hierarchical Study of Giardia lamblias Ventral Disc Reveals Novel Microtubule-Associated Protein Complexes Journal Article ...
Dynein and kinesin motor proteins transport cellular cargoes toward opposite ends of microtubule tracks. In neurons, microtubules are abundantly decorated with microtubule-associated proteins (MAPs) such as tau. Motor proteins thus encounter MAPs frequently along their path. To determine the effects of tau on dynein and kinesin motility, we conducted single-molecule studies of motor proteins moving along tau-decorated microtubules. Dynein tended to reverse direction, whereas kinesin tended to detach at patches of bound tau. Kinesin was inhibited at about a tenth of the tau concentration that inhibited dynein, and the microtubule-binding domain of tau was sufficient to inhibit motor activity. The differential modulation of dynein and kinesin motility suggests that MAPs can spatially regulate the balance of microtubule-dependent axonal transport.. ...
Microtubules are regulated by sensitive mechanisms to accommodate the critical roles that these organelles play at different phases of the cell cycle. Their assembly and disassembly are driven by the binding and hydrolysis of GTP at the plus end of β-tubulin. Microtubule binding proteins such as MAP4, MAP2, and tau bind and promote the assembly and stabilization of microtubules, thereby playing a role in the regulation of microtubules (35, 36). Recently, a group of microtubule-destabilizing proteins has been discovered (37, 38). For example, stathmin, a Mr 19,000 phosphoprotein, binds to α,β-tubulin heterodimers and induces microtubule depolymerization. The integrity and proper function of the microtubule network are further regulated by cell cycle progression signaling molecules and checkpoint mechanisms.. Natural products that mimic the activity of these two classes of microtubule regulatory proteins induce imbalance between microtubule-stabilizing and -destabilizing forces. This kind of ...
Microtubules are filaments of the cytoskeleton. They typically form through the polymerization of α- and β-tubulin dimers elongating existing microtubules. The de novo formation of microtubules requires an initiation event called microtubule nucleation. Microtubule nucleation requires the action of a third type of tubulin, γ-tubulin, which is distinct from the α and β subunits which compose the microtubules themselves. The γ-tubulin combines with several other associated proteins to form a circular structure known as the γ-tubulin ring complex (γ-TuRC). This complex acts as a scaffold for α/β tubulin dimers to begin polymerization. It also acts as a cap of the (−) end while microtubule growth continues towards the (+) direction. The γ-TuRC is typically found as the core functional unit in a microtubule organizing center (MTOC), such as the centrosome in animal cells or the spindle pole bodies in fungi and algae. However, the cells of higher plants for example lack distinct MTOCs and ...
Cytoskeleton inhibitors were used to study morphogenesis in the pathogenic and dimorphic fungus Candida albicans Nocodazole is a specific microtubule inhibitor and chloropropham (CIPC), at high concentrations, is an inhibitor of microtubules and microfilaments. Distribution of microtubules and microfilaments was studied by immunofluorescence techniques using anti-tubulin antibody with FITC-conjugated secondary antibody, and by staining with Rh-phalloidin. Nocodazole did not arrest apical cell elongation at a concentration (20 µg ml−1) that inhibited nuclear division and migration. Cytoplasmic and nuclear microtubules disappeared within 30 min in filamentous cells under these conditions. However, the Rh-phalloidin-stained actin granules which were localized in the tips of filamentous cells, and the microfilaments, were arranged normally at this concentration of nocodazole. Growth, and normal distribution of microtubules and microfilaments, were inhibited by a high concentration (200 µg ml−1) of
1. Howard J. The movement of kinesin along microtubules. Annu Rev Physiol. 1996;58:703-729 2. Hirokawa N. Kinesin and dynein superfamily proteins and the mechanism of organelle transport. Science. 1998;279:519-526 3. Vale RD. The molecular motor toolbox for intracellular transport. Cell. 2003;112:467-480 4. Cross RA. The kinetic mechanism of kinesin. Trends Biochem Sci. 2004;29:301-309 5. Asbury CL. Kinesin: worlds tiniest biped. Curr Opin Cell Biol. 2005;17:89-97 6. Lawrence CJ, Dawe RK, Christie KR. et al. A standardized kinesin nomenclature. J Cell Biol. 2004;167:19-22 7. Howard J, Hudspeth AJ, Vale RD. Movement of microtubules by single kinesin molecules. Nature. 1989;342:154-158 8. Block SM, Goldstein LS, Schnapp BJ. Bead movement by single kinesin molecules studied with optical tweezers. Nature. 1990;348:348-352 9. Svoboda K, Block SM. Force and velocity measured for single kinesin molecules. Cell. 1994;77:773-784 10. Meyhöfer E, Howard J. The force generated by a single kinesin molecule ...
The metaphase spindle is a dynamic bipolar structure crucial for proper chromosome segregation, but how microtubules (MTs) are organized within the bipolar architecture remains controversial. To explore MT organization along the pole-to-pole axis, we simulated meiotic spindle assembly in two dimensions using dynamic MTs, a MT cross-linking force, and a kinesin-5-like motor. The bipolar structures that form consist of antiparallel fluxing MTs, but spindle pole formation requires the addition of a NuMA-like minus-end cross-linker and directed transport of MT depolymerization activity toward minus ends. Dynamic instability and minus-end depolymerization generate realistic MT lifetimes and a truncated exponential MT length distribution. Keeping the number of MTs in the simulation constant, we explored the influence of two different MT nucleation pathways on spindle organization. When nucleation occurs throughout the spindle, the simulation quantitatively reproduces features of meiotic spindles ...
Formation of a bipolar spindle is indispensable for faithful chromosome segregation and cell division. Spindle integrity is largely dependent on the centrosome and the microtubule network. Centrosome protein Cep57 can bundle microtubules in mammalian cells. Its related protein (Cep57R) in Xenopus was characterized as a stabilization factor for microtubule-kinetochore attachment. Here we show that Cep57 is a pericentriolar material (PCM) component. Its interaction with NEDD1 is necessary for the centrosome localization of Cep57. Depletion of Cep57 leads to unaligned chromosomes and a multipolar spindle, which is induced by PCM fragmentation. In the absence of Cep57, centrosome microtubule array assembly activity is weakened, and the spindle length and microtubule density decrease. As a spindle microtubule-binding protein, Cep57 is also responsible for the proper organization of the spindle microtubule and localization of spindle pole focusing proteins. Collectively, these results suggest that ...
Microtubules are dynamic polymers that play crucial roles in a large number of cellular functions. Their pivotal role in mitosis makes them a target for the development of anticancer drugs. Microtubule-damaging agents suppress microtubule dynamics, leading to disruption of the mitotic spindle in dividing cells, cell cycle arrest at M phase, and late apoptosis. A better understanding of the processes coupling microtubule damage to the onset of apoptosis will reveal sites of potential intervention in cancer chemotherapy. Inhibition of microtubule dynamics induces persistent modification of biological processes (M arrest) and signaling pathways (mitotic spindle assembly checkpoint activation, Bcl-2 phosphorylation, c-Jun NH2-terminal kinase activation), which ultimately lead to apoptosis through the accumulation of signals that finally reach the threshold for the onset of apoptosis or through diminishing the threshold for engagement of cell death. Microtubules serve also as scaffolds for signaling ...
Microtubules are dynamic polymers that play crucial roles in a large number of cellular functions. Their pivotal role in mitosis makes them a target for the development of anticancer drugs. Microtubule-damaging agents suppress microtubule dynamics, leading to disruption of the mitotic spindle in dividing cells, cell cycle arrest at M phase, and late apoptosis. A better understanding of the processes coupling microtubule damage to the onset of apoptosis will reveal sites of potential intervention in cancer chemotherapy. Inhibition of microtubule dynamics induces persistent modification of biological processes (M arrest) and signaling pathways (mitotic spindle assembly checkpoint activation, Bcl-2 phosphorylation, c-Jun NH2-terminal kinase activation), which ultimately lead to apoptosis through the accumulation of signals that finally reach the threshold for the onset of apoptosis or through diminishing the threshold for engagement of cell death. Microtubules serve also as scaffolds for signaling ...
Centrosome, besides being a microtubule nucleator, is also important during the cell cycle because it contains many proteins involved in the progress of the cell cycle and in the organization of the mitotic spindle. For example, duplication of centrosomes before mitosis is essential to produce two healthy new cells. In this way, centrosome has been proposed as the cause of different types of cancer since many tumor cells have supernumerary centrosomes that may produce multipolar mitotic spindles and unequal distribution of chromosomes (aneuploidy). There are other cellular places where microtubules can be nucleated. For example, chromosomes during mitosis, cisterns of Golgi apparatus, basal bodies of cilia and flagella, and some new nucleation points sometimes depend on other microtubule. Blepharoplasts (also MTOCs) are molecular complexes of plant cells, occasionally found in animal cells, which are able to nucleate microtubules, and sometimes give rise to centrioles and centrosomes. Plant ...
TY - JOUR. T1 - Delayed start-up of kinesin-driven microtubule gliding following inhibition by adenosine 5′-[β,γ-imido]triphosphate. AU - Schnapp, Bruch J.. AU - Crise, Bruce. AU - Sheetz, Michael. AU - Reese, Thomas S.. AU - Khan, Shahid. PY - 1990/1/1. Y1 - 1990/1/1. N2 - Kinesin is a microtubule-activated ATPase that moves objects toward the plus end of microtubules and makes microtubules glide along a glass surface. Here we investigate a remarkable effect of the nonhydrolyzable analogue of ATP, adenosine 5′-[β,γ-imido]triphosphate (p[NH]ppA), on kinesin-driven microtubule gliding. Microtubule gliding that has been blocked by rapid replacement of ATP with p[NH]ppA requires 1-2 min of exposure to ATP before microtubule gliding resumes. This latency is not shortened by prolonged washing of p[NH]ppA-blocked microtubules in nucleotide-free buffer for up to 15 min, suggesting that ATP binding to a second nucleotide binding site on kinesin triggers the release of bound p[NH]ppA. To test ...
Screening for Arabidopsis mutants that displayed twisted growth of elongating organs and abnormal growth responses to propyzamide resulted in a large collection of dominant-negative tubulin mutants. The data presented here provide some of the strongest evidence to date showing conserved residues of both α- and β-tubulins directly contribute to the stability and helical pattern of cortical microtubule arrays.. Incorporation of mutant tubulins into the microtubule polymer suggests that the structure and/or dynamics of cortical microtubules are altered in these mutants. Many of the affected amino acid residues are located at the longitudinal interface of the α- and β-tubulins within and between the αβ-heterodimer and at the lateral interface between two adjacent protofilaments, indicating that the mutations generally affect the protein-protein interactions but not the stability or the folding of tubulin monomers. Several mutated residues, such as P325 and T439 in α-tubulin and S95 and G96 in ...
The presence of the microtubule-associated protein (MAP2) in the brain of several species has been investigated by SDS-gel electrophoresis and by radioimmunoassay. This assay had a sensitivity of...
Kinesins are a family of motor proteins found in multicellular organisms. They function as little engines within the cells and transport molecular cargo along microtubules, among other activities. The microtubules - 25 nanometers thick or one ten- thousandth the diameter of a human hair - are hollow cylinders of the protein tubulin. They are extremely dynamic and have the ability to grow and shrink as the cell changes shape.. We are trying to get under the hood of these motors and understand what makes their sequences unique, said William Hancock, professor of biomedical engineering, Penn State. Because they carry out so many vital functions in the cells of the body, we really want to understand how they operate at the molecular level.. In total, there are 45 different kinesin motor proteins in humans. Hancock and Yalei Chen, graduate student in cell and developmental biology, Penn States Huck Institute of the Life Sciences, tracked the movements of individual fluorescently-tagged ...
TY - JOUR. T1 - Live cell approaches for studying kinetochore-microtubule interactions in Drosophila.. AU - Buster, Daniel W.. AU - Sharp, David J.. PY - 2007. Y1 - 2007. N2 - Kinetochores are essential for the proper positioning, movement and segregation of chromosomes on spindle microtubules. Live cell analyses of kinetochore movements on the spindle provide an important tool for dissecting the molecular machinery underlying kinetochore-based chromosome motility. Here, we describe contemporary techniques for studying and manipulating kinetochore function in live Drosophila syncytial blastoderm-stage embryos and S2 cells.. AB - Kinetochores are essential for the proper positioning, movement and segregation of chromosomes on spindle microtubules. Live cell analyses of kinetochore movements on the spindle provide an important tool for dissecting the molecular machinery underlying kinetochore-based chromosome motility. Here, we describe contemporary techniques for studying and manipulating ...
Mechanotransduction is a process by which cells sense the mechanical properties of their surrounding environment and adapt accordingly to perform cellular functions such as adhesion, migration and differentiation. Integrin-mediated focal adhesions are major sites of mechanotransduction and their connection with the actomyosin network is crucial for mechanosensing as well as the generation and transmission of forces onto the substrate. Despite having emerged as major regulators of cell adhesion and migration, the contribution of microtubules to mechanotransduction still remains elusive. Here, we show that actomyosin-dependent mechanosensing of substrate rigidity controls microtubule acetylation, a tubulin post-translational modification, by promoting the recruitment of the alpha-tubulin acetyl transferase (αTAT1) to focal adhesions. Microtubule acetylation, in turn, promotes GEF-H1 mediated RhoA activation, actomyosin contractility and traction forces. Our results reveal a fundamental crosstalk between
Biological activities of the 1,4-benzoquinone derivatives 5-O-ethylembelin (1) and 5-O-methylembelin (2) were investigated. Both of them showed anti proliferative activity against a panel of human tumor cell lines upon comparison to normal marsupial kidney cells (PtK2). They arrested HL-60 cells in the G(0)/G(1) phase of the cell cycle in a dose- and time-dependent manner. In HeLa cells, exposure to 100 mu M of 1 or 2 for 6 h induced a complete disassembly of the microtubule network and an increased number of cells blocked in mitotic stages. Treatment with 10 mu M of 1 and 2 for 24 h induced apoptosis in HL-60 cells. This evidence suggests that both 1 and 2 are promising novel antimitotic and anticancer molecules targeting microtubular proteins. ...
RanGTP is important for chromosome-dependent spindle assembly in Xenopus extracts. Here we report on experiments to determine the role of the Ran pathway on microtubule dynamics in Drosophila oocytes and embryos. Females expressing a dominant-negative form of Ran have fertility defects, suggesting that RanGTP is required for normal fertility. This is not, however, because of a defect in acentrosomal meiotic spindle assembly. Therefore, RanGTP does not appear to be essential or sufficient for the formation of the acentrosomal spindle. Instead, the most important function of the Ran pathway in spindle assembly appears to be in the tapering of microtubules at the spindle poles, which might be through regulation of proteins such as TACC and the HURP homolog, Mars. One consequence of this spindle organization defect is an increase in the nondisjunction of achiasmate chromosomes. However, the meiotic defects are not severe enough to cause the decreased fertility. Reductions in fertility occur because ...
RB1 mutational inactivation is a cancer driver in various types of cancer including lung cancer, making it an important target for therapeutic exploitation. We performed chemical and genetic vulnerability screens in RB1-isogenic lung cancer pair and herein report that aurora kinase A (AURKA) inhibition is synthetic lethal in RB1-deficient lung cancer. Mechanistically, RB1−/− cells show unbalanced microtubule dynamics through E2F-mediated upregulation of the microtubule destabilizer stathmin and are hypersensitive to agents targeting microtubule stability. Inhibition of AURKA activity activates stathmin function via reduced phosphorylation and facilitates microtubule destabilization in RB1−/− cells, heavily impacting the bipolar spindle formation and inducing mitotic cell death selectively in RB1−/− cells. This study shows that stathmin-mediated disruption of microtubule dynamics is critical to induce synthetic lethality in RB1-deficient cancer and suggests that upstream factors regulating
As the most rigid cytoskeletal filaments, microtubules bear compressive forces in living cells, balancing the tensile forces within the cytoskeleton to maintain the cell shape. It is often observed that, in living cells, microtubules under compression severely buckle into short wavelengths. By contrast, when compressed, isolated microtubules in vitro buckle into single long-wavelength arcs. The critical buckling force of the microtubules in vitro is two orders of magnitude lower than that of the microtubules in living cells. To explain this discrepancy, we describe a mechanics model of microtubule buckling in living cells. The model investigates the effect of the surrounding filament network and the cytosol on the microtubule buckling. The results show that, while the buckling wavelength is set by the interplay between the microtubules and the elastic surrounding filament network, the buckling growth rate is set by the viscous cytosol. The model quantitatively correlates the microtubule bending ...
As the most rigid cytoskeletal filaments, microtubules bear compressive forces in living cells, balancing the tensile forces within the cytoskeleton to maintain the cell shape. It is often observed that, in living cells, microtubules under compression severely buckle into short wavelengths. By contrast, when compressed, isolated microtubules in vitro buckle into single long-wavelength arcs. The critical buckling force of the microtubules in vitro is two orders of magnitude lower than that of the microtubules in living cells. To explain this discrepancy, we describe a mechanics model of microtubule buckling in living cells. The model investigates the effect of the surrounding filament network and the cytosol on the microtubule buckling. The results show that, while the buckling wavelength is set by the interplay between the microtubules and the elastic surrounding filament network, the buckling growth rate is set by the viscous cytosol. The model quantitatively correlates the microtubule bending ...
Kinesin-8s are plus-end-directed motors that negatively regulate microtubule (MT) length. Well-characterized members of this subfamily (Kip3, Kif18A) exhibit two important properties: (i) They are ultraprocessive, a feature enabled by a second MT-binding site that tethers the motors to a MT track, and (ii) they dissociate infrequently from the plus end. Together, these characteristics combined with their plus-end motility cause Kip3 and Kif18A to enrich preferentially at the plus ends of long MTs, promoting MT catastrophes or pausing. Kif18B, an understudied human kinesin-8, also limits MT growth during mitosis. In contrast to Kif18A and Kip3, localization of Kif18B to plus ends relies on binding to the plus-end tracking protein EB1, making the relationship between its potential plus-end-directed motility and plus-end accumulation unclear. Using single-molecule assays, we show that Kif18B is only modestly processive and that the motor switches frequently between directed and diffusive modes of ...
Griseofulvin, an antifungal drug, has recently been shown to inhibit proliferation of various types of cancer cells and to inhibit tumor growth in athymic mice. Due to its low toxicity, griseofulvin has drawn considerable attention for its potential use in cancer chemotherapy. This work aims to understand how griseofulvin suppresses microtubule dynamics in living cells and sought to elucidate the antimitotic and antiproliferative action of the drug. The effects of griseofulvin on the dynamics of individual microtubules in live MCF-7 cells were measured by confocal microscopy. Immunofluorescence microscopy, western blotting and flow cytometry were used to analyze the effects of griseofulvin on spindle microtubule organization, cell cycle progression and apoptosis. Further, interactions of purified tubulin with griseofulvin were studied in vitro by spectrophotometry and spectrofluorimetry. Docking analysis was performed using autodock4 and LigandFit module of Discovery Studio 2.1. Griseofulvin strongly
TY - JOUR. T1 - Anesthetics act in quantum channels in brain microtubules to prevent consciousness. AU - Craddock, Travis J.A.. AU - Hameroff, Stuart R.. AU - Ayoub, Ahmed T.. AU - Klobukowski, Mariusz. AU - Tuszynski, Jack A.. N1 - Publisher Copyright: © 2015 Bentham Science Publishers.. PY - 2015. Y1 - 2015. N2 - The mechanism by which anesthetic gases selectively prevent consciousness and memory (sparing non-conscious brain functions) remains unknown. At the turn of the 20th century Meyer and Overton showed that potency of structurally dissimilar anesthetic gas molecules correlated precisely over many orders of magnitude with one factor, solubility in a non-polar, hydrophobic medium akin to olive oil. In the 1980s Franks and Lieb showed anesthetics acted in such a medium within proteins, suggesting post-synaptic membrane receptors. But anesthetic studies on such proteins yielded only confusing results. In recent years Eckenhoff and colleagues have found anesthetic action in microtubules, ...
In conclusion, we propose that the mitotic spindle protein She1 functions as an MT cross-linking protein to maintain proper spindle stability during metaphase (Fig. 6 H). There are three major lines of evidence supporting this conclusion: (1) she1-ΔN89 and she1-ΔN126 cells display dynein-independent spindle defects, (2) She1 cross-links MTs in vitro, and (3) the she1-ΔN126 spindle phenotype is complemented by inactivation of Ipl1/Aurora B or by overexpression of she1-ΔN126. The latter shows that premature loading of Ipl1/Aurora B in metaphase inhibits the spindle stabilization effect of she1-ΔN126. Furthermore, we show that this novel activity of She1 is negatively regulated by Ipl1/CPC translocation during anaphase.. Recent work suggested that, during the establishment of a functional metaphase spindle midzone (Hepperla et al., 2014), passive cross-linking proteins are required to maintain proper bundling within the spindle once ipMTs are aligned along the spindle axis by kinesin-14 ...
Microtubule nucleation for anastral spindle assembly is dependent on chromatin, differing from astral spindles; however, the mechanism of nucleation is still not certain. The initial stages in formation of anastral Drosophila oocyte MI spindles have been studied by imaging live oocytes injected with rhodamine-tubulin [33] or expressing the kinesin-14 Ncd motor fused to GFP to visualize the spindle [20]. Microtubule growth from the condensed MI chromosomes or karyosome was observed in both cases, providing evidence that microtubule nucleation occurs from chromatin, as first observed in Xenopus extract spindles [1]. Time-lapse images obtained with Ncd-GFP showed small fluorescent foci or asters that migrated towards and associated with the karyosome, after which spindle microtubules grew out in all directions from the chromosomes [20]. The asters were also observed labeled with rhodamine-tubulin but were thought not to play a role in spindle assembly, in part because they were not associated with ...
With six putative armadillo repeat domains and a single C-terminal C2 domain, CSI3 shares 66% similarity with CSI1 in amino acid sequence. CSI1 interacted with multiple primary CESAs in a yeast two-hybrid assay (Gu et al., 2010), and CSI3 interacted with multiple primary CESAs in a split-ubiquitin yeast two-hybrid assay. The behavior of fluorescent protein fusions of CSI3 and CSI1 was similar. CSI1 and CSI3 each localized to the plasma membrane as discrete particles that colocalized with CSCs and traveled along cortical microtubule tracks at comparable velocities. However, despite these similarities, CSI3 appears to have a role that is distinct from CSI1 based on several observations. Unlike csi1 mutants, which exhibit short and swollen dark-grown hypocotyls, csi3 mutants do not exhibit an apparent phenotype. Also, in contrast with csi1 mutants, which exhibit CSCs that travel at reduced velocities along tracks that are no longer organized along microtubules, csi3 mutants do not have detectable ...
135. Abstract Microfibrillar structure, cortical microtubule orientation and the effect of amiprophos-methyl (APM) on the arrangement of the most recently deposited cellulose microfibrils were investigated in the marine filamentous green alga, Chamaedoris orientalis. The thallus cells of Chamaedoris showed typical tip growth. The orientation of microfibrils in the thick cell wall showed orderly change in longitudinal, transverse and oblique directions in a polar dependent manner. Microtubules run parallel to the longitudinally arranged microfibrils in the innermost layer of the wall but they are never parallel to either transverse or obliquely arranged microfibrils. The ordered change in microfibril orientation is altered by the disruption of the microtubules with APM. The walls, deposited in the absence of the microtubules, showed typical helicoidal pattern. However, the original crossed polylamellate pattern was restored by the removal of APM. This suggests that cortical microtubules in this ...
The inability to faithfully segregate chromosomes in mitosis results in chromosome instability, a hallmark of solid tumors. Disruption of microtubule dynamics contributes highly to mitotic chromosome instability. The kinesin-13 family is critical in the regulation of microtubule dynamics and the best characterized member of the family, the mitotic centromere-associated kinesin (MCAK), has recently been attracting enormous attention. MCAK regulates microtubule dynamics as a potent depolymerizer of microtubules by removing tubulin subunits from the polymer end. This depolymerizing activity plays pivotal roles in spindle formation, in correcting erroneous attachments of microtubule-kinetochore and in chromosome movement. Thus, the accurate regulation of MCAK is important for ensuring the faithful segregation of chromosomes in mitosis and for safeguarding chromosome stability. In this review we summarize recent data concerning the regulation of MCAK by mitotic kinases, Aurora A/B, Polo-like kinase 1 ...
Intracellular transport plays an essential role in maintaining the organization of polarized cells. Motor proteins tether and move cargos along microtubules during long-range transport to deliver them to their proper location of function. To reach their destination, cargo-bound motors must overcome barriers to their forward motion such as intersection points between microtubules. The ability to visualize how motors navigate these barriers can give important information about the mechanisms that lead to efficient transport. Here, we first develop an all-optical correlative imaging method based on single-particle tracking and superresolution microscopy to map the transport trajectories of cargos to individual microtubules with high spatiotemporal resolution. We then use this method to study the behavior of lysosomes at microtubule-microtubule intersections. Our results show that the intersection poses a significant hindrance that leads to long pauses in transport only when the separation distance of the
Microtubules (MTs) exhibit dynamic instability, alternating between phases of growth and shortening, mostly at their uncapped plus ends. Based on results from cryo-electron microscopy it was proposed that growing MTs display mainly curved sheets and blunt ends; during depolymerisation curled ramshorns predominate. Observations of MTs in mitotic cells have suggested that the situation in vivo differs from that in vitro, but so far, a clear comparison between in vivo and in vitro results has not been possible because MT end structures could not be correlated directly with the dynamic state of that particular MT. Here we combine light microscopy and electron tomography (ET) to show that growing MT plus ends in the fission yeast Schizosaccharomyces pombe display predominantly a flared morphology. This indicates that MT polymerisation in vivo and in vitro can follow different paths.. ...
In this paper, we characterized the Dis1/XMAP215 family protein AlpA from A. nidulans and found that it is associated with the MT plus end during mitosis and in interphase. AlpA plays a role in controlling MT dynamics and is important for the determination of growth polarity. Whereas the mechanism of MT stabilization was recently shown in S. cerevisiae (1), a role in polarized growth has not been described before. Polarized growth of filamentous fungi depends on the continuous delivery of secretory vesicles (7, 20). These vesicles provide new membranes and deliver, e.g., enzymes for cell wall biosynthesis. Because the vesicles are generated some distance away from the growing tip, they need to be transported long distances. It is assumed that MTs and conventional kinesin provide the basis for this long-distance transportation (18, 23). The first destination of the vesicles is an organelle close to the apex named the vesicle supply center or Spitzenkörper (8). The location of this organelle ...
for: The role of the subpellicular microtubule array in Trypanosoma brucei cytokinesis Microtubules are essential cytoskeletal filaments in eukaryotic cells. Th...
Cancer metastasis causes the increase of mortality in most cancer patients, and abnormal cell migration contributes to this disease progression. To control cell migration, the dynamical control of a protein complex within focal adhesions has to be regulated appropriately. It is known that focal adhesions can be regulated dynamically by microtubules. To examine the effects of centrosomal microtubules and non-centrosomal microtubules in regulating focal adhesion dynamics and directed cell migration, we first generated centrosome-deficient cells. We find that centrosomal microtubules and non-centrosomal microtubules control focal adhesion dynamics through modulating focal adhesion composition, which dynamically control the activity of small GTPases Rac1 and Cdc42. Deficiency of centrosomal microtubules significantly disrupts the balance of Rac1 and Cdc42, thereby inhibiting directed cell migration. This study reveals the effects of centrosome in focal adhesions, and indicates an important role for ...
Cooper, Geoffrey M. (2000). "Microtubules". The Cell: A Molecular Approach. 2nd edition. Faron-Górecka, Agata; Szlachta, Marta ... is formed by the dimerization of α-tubulin and β-tubulin and this dimer can then polymerize further to make microtubules. For ...
Microtubule plus end tracking proteins (+TIPs) are MAPs that accumulates in the plus end of microtubules. In neurotubules, + ... Microtubule-associated proteins (MAPs) are proteins that interact with microtubules by binding to their tubulin subunits and ... Microtubule Neurofilament Tubulin Microtubule associated protein Neuronal migration "Medical Definition of NEUROTUBULE". www. ... Most neurotubules are not anchored in the microtubule organizing center (MTOC) like conventional microtubules do. Instead, they ...
Ledbetter, M. C.; Porter, K. R. (October 1, 1963). "A "Microtubule" in Plant Cell Fine Structure". The Journal of Cell Biology ... Slautterback, David B. (August 1, 1963). "Cytoplasmic Microtubules". The Journal of Cell Biology. 18 (2): 367-388. doi:10.1083/ ... microtubules, intermediate filaments, tight junctions (including occludins and claudins), adherens junctions, and cadherins. ...
... and became interested in the mechanisms involved in microtubule organization in cells that lacked a microtubule-organizing ... including publishing the first report suggesting a co-alignment of microtubules with cell wall cellulose microtubules. A ... Hepler realized that microtubules were dynamic structures that were deployed in various locations throughout the cell, ... Hepler, P. K.; W. T. Jackson (1968). "Microtubules and early stages of cell plate formation in the endosperm of Haemanthus ...
Das M, Chiron S, Verde F (2010). "Microtubule-dependent spatial organization of mitochondria in fission yeast". Microtubules: ...
... also promote the capture of microtubules by the kinetochore during mitosis and for aligning microtubules along actin ... Formins also directly bind to microtubules via their FH2 domain. This interaction is important in promoting the capture and ... Formins regulate the actin and microtubule cytoskeleton and are involved in various cellular functions such as cell polarity, ... The addition of the DAD to mammalian cells induces actin filament formation, stabilizes microtubules, and activates SRF ...
Microtubules are polar; meaning, the heads only bind to the microtubule in one orientation, while ATP binding gives each step ... microtubule-bound state results in a tilting of the kinesin motor domain relative to the microtubule. Critically, prior to this ... q r = e E K B T {q \over r}=e^{E \over K_{B}T} In recent years, it has been found that microtubule-based molecular motors ( ... One can understand that the rates of entrance and exit in the microtubule will be changed as well by the energy (See figure 1 ...
His work on the dynamics of microtubules is known to have assisted in the development of anti-cancer and anti-fungal drugs and ... Presently, he is the Director of NIPER, SAS Nagar (Mohali). Known for his studies on microtubule dynamics and FtsZ assembly ... Panda's cell biological research covered the fields of eukaryotic and prokaryotic cell division, dynamics of microtubules and ... Banerjee, Mithu; Singh, Parminder; Panda, Dulal (1 August 2010). "Curcumin suppresses the dynamic instability of microtubules, ...
Unlike actin filaments, microtubules are stiff, hollow structures that radiate outwards from the microtubule organizing center ... "Microtubules and Filaments". Scitable by Nature Education. "What are intermediate filaments? , MBInfo". ... In terms of cell mechanics, microtubules' main purpose is to resist compressive cellular forces and act as a transportation ... The largest cytoskeletal structure of the three types of polymers is the microtubules with a diameter of 25 nm. ...
Tubulin/microtubule-targeted pharmacology for atherosclerosis. Concept of the neurotrophins NGF and BDNF as metabotrophic ... Role of microtubules". Acta Morphologica Academiae Scientiarum Hungaricae. 25 (2-3): 167-174. PMID 615419. Chaldakov GN, Vankov ...
December 2002). "Nanomechanics of microtubules" (PDF). Physical Review Letters. 89 (24): 248101. Bibcode:2002PhRvL..89x8101K. ... actin filaments and microtubules. For a description of atomic force microscopy (AFM), see atomic force microscopy. AFM has been ...
... which is the microtubule organizing center for flagellar microtubules and is about 500 nanometers long. Basal bodies are ... Each of the outer 9 doublet microtubules extends a pair of dynein arms (an "inner" and an "outer" arm) to the adjacent ... The flagella in eukaryotes have dynein and microtubules that move with a bending mechanism. Bacteria and archaea do not have ... Haimo LT, Rosenbaum JL (December 1981). "Cilia, flagella, and microtubules". The Journal of Cell Biology. 91 (3 Pt 2): 125s- ...
It is structurally a complex of microtubules along with motor proteins. The usage of the term was early supported by Lynn ... Undulipodia are an extension of the cell membrane containing both cytoplasm and a regular arrangement of microtubules known as ... Haimo LT, Rosenbaum JL (December 1981). "Cilia, flagella, and microtubules". J. Cell Biol. 91 (3 Pt 2): 125s-130s. doi:10.1083/ ... The kinetosome mediates movement through a chemical reaction, causing the microtubules to slide against one another and the ...
Most motile cilia have a central pair of single microtubules surrounded by nine pairs of double microtubules called a 9+2 ... Two of each of the basal body's triplet microtubules extend during growth of the axoneme to become the doublet microtubules. ... At the base of the cilium where it attaches to the cell body is the microtubule organizing center, the basal body. Some basal ... Non-motile cilia that have a central pair of microtubules are the kinocilia present on hair cells. Motile cilia are found in ...
One of them is to use molecules that can induce the stabilization of microtubules, and Pyr1 is one of them. Pyr1 may be used in ... LIMK1 also depolymerizes microtubules. In the presence of Pyr1, LIMK1 is inhibited, which means that the phosphorylation of ... Microtubules have a key role in mitosis: they generate the mitotic spindle assembly, which allows chromosome segregation and ... That is why microtubule targeting agents are, nowadays, powerful anticancer drugs. It also explains why tubulin is now ...
Bermudes D, Hinkle G, Margulis L (1994). "Do prokaryotes contain microtubules?". Microbiol. Rev. 58 (3): 387-400. doi:10.1128/ ...
The model microtubule on which they base their Hamiltonian is not a microtubule structure, but a simple linear chain of ... Microtubules are made up of tubulin protein subunits. The tubulin protein dimers of the microtubules have hydrophobic pockets ... Hameroff then proposed that condensates in microtubules in one neuron can link with microtubule condensates in other neurons ... and particularly on microtubules. As neuroscience has progressed, the role of the cytoskeleton and microtubules has assumed ...
Iijima, Sumio (November 1991). "Helical microtubules of graphitic carbon". Nature. 354 (6348): 56-58. Bibcode:1991Natur.354... ...
doi:10.1016/S0040-4039(00)95060-3. Iijima, S. (1991). "Helical microtubules of graphitic carbon". Nature. 354 (6348): 56-58. ...
In addition to providing a supportive structure for the cell, the known functions of the microtubules include transport of ... The objective collapse of the quantum wavefunction of the microtubules is critical for consciousness. The collapse in question ... Hameroff, S.R. & Watt, R.C. (1982). "Information processing in microtubules" (PDF). Journal of Theoretical Biology. 98 (4): 549 ... Hagan, S., Hameroff, S., and Tuszyński, J. (2002). "Quantum Computation in Brain Microtubules? Decoherence and Biological ...
Hameroff provided a hypothesis that microtubules would be suitable hosts for quantum behavior. Microtubules are composed of ... But if you go down to the level of the microtubules, then there's an extremely good chance that you can get quantum-level ... For my picture, I need this quantum-level activity in the microtubules; the activity has to be a large-scale thing that goes ... Orch-OR predicted that microtubule coherence reaches the synapses through dendritic lamellar bodies (DLBs), but De Zeeuw et al ...
cite journal}}: Cite journal requires ,journal= (help) Iijima, Sumio (7 November 1991). "Helical microtubules of graphitic ... 9 March 1992). "New One-Dimensional Conductors: Graphitic Microtubules". Physical Review Letters. 68 (10): 1579-1581. Bibcode: ...
These microtubules form an axoneme. Later the centriole is modified in the process of centrosome reduction. The anterior part ... During spermiogenesis, the spermatids begin to form a tail by growing microtubules on one of the centrioles, which turns into ...
... acts by depolymerizing microtubules. Benomyl is also useful in the laboratory because it is selectively toxic to most ... "Novel Response to Microtubule Perturbation in Meiosis". Molecular and Cellular Biology. 25 (11): 4767-4781. doi:10.1128/MCB. ...
"Optimal dynamic instability of microtubules". Doc. Math. (Bielefeld) Extra Vol. ICM Berlin, 1998, vol. III. pp. 633-642. James ...
Dynamins are associated with microtubules. They have been implicated in cell processes such as endocytosis and cell motility, ...
Microtubule nucleated in vitro in the presence of Doublecortin have almost exclusively 13 protofilaments, whereas microtubule ... Doublecortin is a basic protein with an iso-electric point of 10 typical of microtubule-binding proteins. In mice where the ... Gleeson JG, Lin PT, Flanagan LA, Walsh CA (1999). "Doublecortin is a microtubule-associated protein and is expressed widely by ... Doublecortin was found to bind to the microtubule cytoskeleton. In vivo and in vitro assays show that Doublecortin stabilizes ...
Examples include nucleosomes and microtubules. Changes in quaternary structure can occur through conformational changes within ...
... pulls the microtubules and chromosomes to one end of the cell. When the end of the microtubules become close to the cell ... that binds to the microtubule, and an extended tail (or "stem") that attaches to a neighboring microtubule of the same axoneme ... Cytoplasmic dynein moves processively along the microtubule; that is, one or the other of its stalks is always attached to the ... One projection, the coiled-coil stalk, binds to and "walks" along the surface of the microtubule via a repeated cycle of ...
Ferrari Toninelli G, Spano P, Memo M (2003). "TorsinA, microtubules and cell polarity". Funct. Neurol. 18 (1): 7-10. PMID ...
Microtubule acetylation, in turn, promotes the release of the guanine nucleotide exchange factor GEF-H1 from microtubules to ... Substrate-rigidity-dependent microtubule acetylation is now shown to be triggered by mechanosensing at focal adhesions, and in ... Microtubule acetylation tunes the mechanosensitivity of focal adhesions and Yes-associated protein (YAP) translocation. ... Despite having emerged as major regulators of cell adhesion and migration, the contribution of microtubules to ...
... as fuel to move back and forth along a microtubule. With each step, the motor molecule releases one portion of the microtubule ... For all microtubules, the minus end is the one with exposed alpha-tubulins. In an animal cell, it is this end that is located ... In a microtubule, the subunits are organized in such a way that they all point the same direction to form 13 parallel ... Microtubules, which are about 25 nanometers in diameter, form part of the cytoskeleton that gives structure and shape to a cell ...
Microtubule associated protein 9 inhibits liver tumorigenesis by suppressing ERCC3. Title: Microtubule associated protein 9 ... microtubule associated protein 9provided by HGNC. Primary source. HGNC:HGNC:26118 See related. Ensembl:ENSG00000164114 MIM: ... XM_011532255.4 → XP_011530557.1 microtubule-associated protein 9 isoform X3. Conserved Domains (1) summary. cl01868. Location: ... XM_017008616.2 → XP_016864105.1 microtubule-associated protein 9 isoform X2. Conserved Domains (2) summary. PTZ00121. Location: ...
This study was designed to examine ciliary structure during the different stages of ciliary inhibition in freshwater mussels. Rapid microtubular disappearance occurs in the terminal cilia of the freshwater mussel Unio when exposed to cystic fibrosis (CF) serum causing a shock stop reaction. Return to water allows resumption of normal ciliary beating. In contrast, a slow stop reaction causes distor
... central spindle proteins and cortical proteins could regulate the position of the contractile ring by stabilizing microtubule- ... Microtubules Is the Subject Area "Microtubules" applicable to this article? Yes. No. ...
Interphase microtubules (green) are labeled with alpha/beta tubulin primary antibodies. FITC conjugated secondary anti... ...
Microtubule-bound mutant M1 decreased microtubule dynamics, whereas unbound M1 or M87 mutant spastins increased microtubule ... Spastin is a microtubule-severing ATPase that breaks longer microtubules (MTs) into shorter ones (Errico et al., 2002; Evans et ... 2005) Linking axonal degeneration to microtubule remodeling by spastin-mediated microtubule severing. J Cell Biol 16:599-606, ... 2006) The microtubule-severing protein Spastin is essential for axon outgrowth in the zebrafish embryo. Hum Mol Genet 15:2763- ...
Eribulin mesylate as a microtubule inhibitor for treatment of patients with metastatic breast cancer ... Eribulin mesylate as a microtubule inhibitor for treatment of patients with metastatic breast cancer. ... Eribulin mesylate (E7389) is a nontaxane microtubule dynamics inhibitor, and a structurally simplified synthetic analog of the ...
User:Andy Maloney/Kinesin & Microtubule Page/Surface passivation/Caseins of various origins and biologically active casein ... Retrieved from " ...
Microtubules most used tags. bones break carrots crack cracking crunching cut gore sfx snapping ... Microtubules latest sounds. Melon beating.wav - mp3 version Melon beating.wav - ogg version Melon beating.wav - waveform Melon ...
Fluorescent dyes and probes for super-resolution microscopy of microtubules and tracheoles in living cells and tissues† ... Fluorescent dyes and probes for super-resolution microscopy of microtubules and tracheoles in living cells and tissues G. ... Combined tubulin and taenidia STED imaging showed close interaction between the microtubules and respiratory networks in living ... Application to living fruit fly (Drosophila melanogaster) tissues highlighted two distinct structures: microtubules and ...
Le cytosquelette de microtubule (MT) est essentiel dans de nombreux processus cellulaire. Il est notamment impliqué dans le ... Keywords : Microtubules Evanescent wave microscopy Microtubules Associated proteins (MAPs) Nano patterning Cytoskeleton ... Dynamic assembly of microtubules and molecular mecanisms involved in the microtubule network during cellular morphogenesis ... Mots-clés : Protéines associées aux microtubules Micro-nanofabrication Microscopie à onde évanescente Microtubules ...
Microtubule-Actomyosin Mechanical Cooperation during Contact Guidance Sensing. Cell Reports. 2018 Oct 9;25(2):328-338.e6. doi: ... Microtubule-Actomyosin Mechanical Cooperation during Contact Guidance Sensing. In: Cell Reports. 2018 ; Vol. 25, No. 2. pp. 328 ... Microtubule-Actomyosin Mechanical Cooperation during Contact Guidance Sensing. Erdem D. Tabdanov, Vikram Puram, Alexander ... Microtubule-Actomyosin Mechanical Cooperation during Contact Guidance Sensing. / Tabdanov, Erdem D.; Puram, Vikram; Zhovmer, ...
Consistent handedness of microtubule helical arrays in maize and Arabidopsis primary roots journal, March 1996 * Liang, B. M.; ... Cortical microtubule arrays undergo rotary movements in Arabidopsis hypocotyl epidermal cells journal, January 2007 * Chan, ... Microtubules and Microfilaments journal, June 1974 * Hepler, P. K.; Palevitz, B. A. ... Microtubules and CESA tracks at the inner epidermal wall align independently of those on the outer wall of light-grown ...
Microtubule in the largest biology dictionary online. Free learning resources for students covering all major areas of biology. ... The hollow space inside the microtubule is referred to as the lumen. Since a microtubule is made up of α-/β-tubulin dimers, it ... In prokaryotes though the microtubule is often comprised of five instead of 13.. In cilia and flagella, microtubules assemble ... There are three main subgroups of microtubules: the polar microtubules (those extending across the cell, as in from centrosome ...
Removal of the EMAP from the microtubule by salt-extraction results in the release of ribosomes from the microtubule, ... Large numbers of ribosomes are attached to the walls of EMAP-containing microtubules, but not EMAP-deficient microtubules. ... Suprenant, KA; Dean, K; McKee, J; Hake, S. EMAP, an echinoderm microtubule-associated protein found in microtubule-ribosome ... A cross-reacting polypeptide, ranging in M(r) from 72,000 to 80,000, was found in microtubule preparations from a wide variety ...
Here, we describe the protocols we use to observe microtubules assembled in vitro in the presence of XMAP215, a large and ... can be applied to study the interaction of proteins that show disorder and/or bind in a nonregular fashion to microtubules. ... flexible protein that binds to discrete sites on the microtubule lattice. Gold particles are added to the mix before ... Cryo-Electron Tomography of microtubules assembled in vitro from purified components. Frédéric M. Coquelle 1 Sophie Blestel 1, ...
The subpellicular microtubule-based cytoskeleton of Trypanosoma brucei is, in comparison to the highly dynamic microtubules of ... In addition to the presence of microtubule-associated proteins important determinants of microtubule (MT) function are a ... Consequences of microtubule posttranslational modifications on the physics of the parasite Trypanosoma brucei ... P5 - Consequences of microtubule posttranslational modifications on the physics of the parasite Trypanosoma brucei. ...
However, the automatic detection of microtubules in electron tomograms is a difficult task due to the low contrast of the data ... Consequently, simple properties, such as the length of microtubules in the spindle or their number, are still unknown for most ... In this thesis, we present methods for 1) an automatic segmentation of microtubule centerlines in electron tomograms, and 2) an ... Software for automatically segmentation and stitching of the microtubules are not available and therefore these tasks have to ...
Disassembly of microtubules by intense terahertz pulses med./bio. By: Hough CM, Purschke DN, Bell C, Kalra AP, Oliva PJ, Huang ...
The Microtubule Depolymerizing Agent CYT997 Causes Extensive Ablation of Tumor Vasculature In Vivo. Christopher J. Burns, ... The orally active microtubule-disrupting agent (S)-1-ethyl-3-(2-methoxy-4-(5-methyl-4-((1-(pyridin-3-yl)butyl)amino)pyrimidin-2 ... The Microtubule Depolymerizing Agent CYT997 Causes Extensive Ablation of Tumor Vasculature In Vivo ...
Budding yeast Spc110, a member of γ-tubulin complex receptor family (γ-TuCR), recruits γ-tubulin complexes to microtubule (MT) ... Cell-cycle dependent phosphorylation of yeast pericentrin regulates γ-TuSC-mediated microtubule nucleation. ... Cell-cycle dependent phosphorylation of yeast pericentrin regulates γ-TuSC-mediated microtubule nucleation ... Cell-cycle dependent phosphorylation of yeast pericentrin regulates γ-TuSC-mediated microtubule nucleation ...
... DSpace/Manakin Repository. ... Keywords: NMR spectroscopy, solid-state NMR, microtubule, microtubule-associated protein, structural biology ... Microtubule-associated proteins (MAPs) are critically involved in such MT dynamics by binding to MTs and reshaping the ... The dynamic instability of microtubules (MT) is an essential feature in eukaryotic cells and related to basic cellular ...
This position data can then be analyzed to obtain event information for an individual microtubule, as well as statistical data ... individual microtubule positions can be tracked over time. ... for a group of microtubules. An event can be one of three types ... Given a set of cell microtubule images taken at regular time intervals, ... Given a set of cell microtubule images taken at regular time intervals, individual microtubule positions can be tracked over ...
Antimitotic diterpenes from Erythropodium caribaeorum test pharmacophore models for microtubule stabilization. Publication Type ... Structural variations encountered in this group of natural products test recently proposed pharmacophore models for microtubule ...
The microtubule motor cytoplasmic dynein is required for spindle orientation during germline cell divisions and oocyte ... M. McGrail, T.S. Hays; The microtubule motor cytoplasmic dynein is required for spindle orientation during germline cell ... Cell-cell signaling, microtubules and the loss of symmetry in the Drosophila oocyte. ... The localization of dynein in mitotic cysts suggests spindle orientation is mediated by the microtubule motor cytoplasmic ...
Microtubule depolymerization restored LV contractile function both in vivo and in vitro. CONCLUSIONS: These and additional ... One such mechanism established in vitro is densification of the cellular microtubule network, which imposes a viscous load that ... corroborative data show that increased cardiocyte microtubule network density is an important mechanism for the ventricular ... Microtubule depolymerization restored LV contractile function both in vivo and in vitro. CONCLUSIONS: These and additional ...
Independent variability of microtubule perturbations associated with dystrophinopathy. Joseph J. Belanto, John T. Olthoff, Tara ... Dive into the research topics of Independent variability of microtubule perturbations associated with dystrophinopathy. ...
Sister Centromere:Kinetochore:Microtubules [cytosol] (Bos taurus) Sister Centromere:Kinetochore:Microtubules [cytosol] (Canis ... Sister Centromere:Kinetochore:Microtubules [cytosol] (Gallus gallus) Sister Centromere:Kinetochore:Microtubules [cytosol] (Mus ... Sister Centromere:Kinetochore:Microtubules [cytosol] (Sus scrofa) Sister Centromere:Kinetochore:Microtubules [cytosol] (Xenopus ... Sister Centromere:Kinetochore:Microtubules [cytosol] (Danio rerio) ...
  • Microtubules, which are about 25 nanometers in diameter, form part of the cytoskeleton that gives structure and shape to a cell, and also serve as conveyor belts moving other organelles throughout the cytoplasm. (
  • The microtubule (MT) cytoskeleton is essential for many cell processes, such as the intracellular trafficking, the cell division, and the cell morphogenesis. (
  • Cytoskeleton is a cytoplasmic structure composed of protein filaments and microtubules in the cytoplasm, and has a role in controlling cell shape, maintaining intracellular organization, and in cell movement. (
  • In eukaryotes, there are three major types of cytoskeleton, namely (1) microfilaments, (2) microtubules, and (3) intermediate filaments. (
  • The microtubules are cytoplasmic tubules that serve as structural components of cytoskeleton, cilia, and eukaryotic flagella. (
  • The subpellicular microtubule-based cytoskeleton of Trypanosoma brucei is, in comparison to the highly dynamic microtubules of higher eukaryotes, extremely stable and its main purpose appears to provide structural integrity to the parasite. (
  • tubular structures within cells that help to support the cytoskeleton and maintain the structure of the cell, microtubules are also essential to a number of cellular processes like transporting cellular components throughout the cell. (
  • Trypanosoma brucei has a precisely ordered microtubule cytoskeleton whose morphogenesis is central to cell cycle events such as organelle positioning, segregation, mitosis, and cytokinesis. (
  • In addition, microtubules are the major components of cilia and flagella, and participate in the formation of spindle fibers during cell division (mitosis). (
  • Photostatins modulate microtubule dynamics with a subsecond response time and control mitosis in living organisms with single-cell spatial precision. (
  • The regulation of microtubule dynamics is critical to ensure essential cell functions, such as proper segregation of chromosomes during mitosis or cell polarity and migration. (
  • Using immunofluorescence and live cell imaging, we showed that TH588 rapidly reduced microtubule plus-end mobility, disrupted mitotic spindles, and prolonged mitosis in a concentration-dependent but MTH1-independent manner. (
  • Inhibition of microtubule dynamics by rhizoxin results in a phenomenon whereby cells, which have segregated their kinetoplasts yet are compromised in mitosis, cleave into a nucleated portion and a flagellated, anucleate, cytoplast. (
  • Centromeric nucleosomes are at the interface of the chromosome and the kinetochore that connects to spindle microtubules in mitosis. (
  • Microtubule-bound mutant M1 decreased microtubule dynamics, whereas unbound M1 or M87 mutant spastins increased microtubule dynamics. (
  • The alterations in microtubule dynamics observed in the presence of mutated spastins are not consistent with haploinsufficiency and are better explained by a gain-of-function mechanism. (
  • Eribulin mesylate (E7389) is a nontaxane microtubule dynamics inhibitor, and a structurally simplified synthetic analog of the natural marine product, halichondrin B, with a novel mechanism of action that has shown antitumor activity in pretreated MBC. (
  • Furthermore, we show that Arp2/3-dependent lamellipodia dynamics can compete with aligned protrusions to diminish the CG response and define Arp2/3- and Formins-dependent actin architectures that regulate microtubule-dependent protrusions, which promote the CG response. (
  • Microtubule-associated proteins (MAPs) are critically involved in such MT dynamics by binding to MTs and reshaping the molecular and structural organization. (
  • Small molecules that interfere with microtubule dynamics, such as Taxol and the Vinca alkaloids, are widely used in cell biology research and as clinical anticancer drugs. (
  • Here, we introduce the photostatins, inhibitors that can be switched on and off in vivo by visible light, to optically control microtubule dynamics. (
  • The authors determined that while actin plays no role in spindle collapse, microtubule dynamics are necessary for spindle collapse. (
  • In this paper we present a model for estimation of the C-terminal tubulin tail (CTT) dynamics in cytoskeletal microtubules of nerve cells. (
  • G mutation caused the reduced levels and deficient phosphorylation of MAP1B, which are involved in the microtubule stability and dynamics. (
  • Strikingly, otic sensory neuron-like cells exhibited disturbed dynamics of microtubules, axonal elongation, and defects in electrophysiological properties. (
  • The spiral ganglion neurons isolated from Map1b mutant mice exhibited the deficient phosphorylation and disturbed dynamics of microtubules. (
  • End-binding protein 1 (EB1) is a plus-end-tracking protein (+TIP) that accumulates at growing microtubule ends and plays a pivotal role in the regulation of microtubule dynamics. (
  • Microtubule polarity and dynamics in the control of organelle positioning, segregation, and cytokinesis in the trypanosome cell cycle. (
  • Regulation of microtubule (MT) dynamics is key for mitotic spindle assembly and faithful chromosome segregation. (
  • Microtubule acetylation tunes the mechanosensitivity of focal adhesions and Yes-associated protein (YAP) translocation. (
  • Microtubules are biopolymers that are composed of subunits made from an abundant globular cytoplasmic protein known as tubulin , as illustrated in Figure 1. (
  • ASAP is a microtubule-associated protein required for spindle function, mitotic progression, and cytokinesis (Saffin et al. (
  • Microtubule associated protein 9 inhibits liver tumorigenesis by suppressing ERCC3. (
  • Mutations to the SPG4 gene encoding the microtubule-severing protein spastin are the most common cause of hereditary spastic paraplegia. (
  • There are three main subgroups of microtubules: the polar microtubules (those extending across the cell, as in from centrosome to centrosome), the astral microtubules (those that anchor the spindle poles to the cell membrane), and the kinetochore microtubules (those that extend from the centrosome to the kinetochore protein in the centromere of the chromosome). (
  • Because the 77,000 M(r) MAP is abundant in echinoderms, we have called it EMAP for echinoderm microtubule-associated protein. (
  • Here, we describe the protocols we use to observe microtubules assembled in vitro in the presence of XMAP215, a large and flexible protein that binds to discrete sites on the microtubule lattice. (
  • Cytoplasmic linker protein (CLIP)-170 is definitely a microtubule (MT) plus-end-tracking protein that regulates MT mechanics and links MT in addition ends to different intracellular structures. (
  • Association of mitochondria with microtubules inhibits mitochondrial fission by precluding assembly of the fission protein Dnm1. (
  • Using the whole exome sequencing approach, in combination with functional assays and a mouse disease model, we identified the potentially novel deafness-causative MAP1B gene encoding a highly conserved microtubule-associated protein. (
  • The microtubule associated protein tau H1 haplotype and risk of essential tremor. (
  • Here, we show that talin- and actomyosin-dependent mechanosensing of substrate rigidity controls microtubule acetylation (a tubulin post-translational modification) by promoting the recruitment of α-tubulin acetyltransferase 1 (αTAT1) to focal adhesions. (
  • Each subunit of the microtubule is made of two slightly different but closely related simpler units called alpha -tubulin and beta -tubulin that are bound very tightly together to form heterodimers . (
  • By adding or removing globular tubulin proteins, the length of polymeric microtubules can be increased or decreased. (
  • Microtubules are continuously being assembled and disassembled so that tubulin monomers can be transported elsewhere to build microtubules when needed. (
  • Interphase microtubules (green) are labeled with alpha/beta tubulin primary antibodies. (
  • Combined tubulin and taenidia STED imaging showed close interaction between the microtubules and respiratory networks in living tissues of the insect larvae. (
  • In eukaryotes, a microtubule is made up of polymers of alpha - and beta -tubulin dimers. (
  • Since a microtubule is made up of α-/β-tubulin dimers, it exhibits polarity as one end could be α-tubulin (- end) and the other end, β-tubulin (+ end). (
  • The microtubule forms from the polymerization of two types of globular proteins (particularly α- and β-tubulin) forming linear filaments called protofilaments . (
  • The major non-tubulin polypeptide found associated with microtubules purified from unfertilized sea urchin eggs by cycles of pH-dependent assembly has a M(r) of 77,000. (
  • Budding yeast Spc110, a member of γ-tubulin complex receptor family (γ-TuCR), recruits γ-tubulin complexes to microtubule (MT) organizing centers (MTOCs). (
  • In addition, 3,5,4′-trimethoxystilbene acts as a vascular-targeting agent by causing microtubule disassembling and tubulin depolymerization and by impairing the repositioning of the microtubule organization center and the formation of membrane ruffles in migrating endothelial cells. (
  • Structural model for tubulin recognition and deformation by Kinesin-13 microtubule depolymerases. (
  • EB1 autonomously binds an extended tubulin-GTP/GDP-Pi structure at growing microtubule ends and acts as a molecular scaffold that recruits a large number of regulatory +TIPs through interaction with CAP-Gly or SxIP motifs. (
  • Our results reveal a fundamental crosstalk between microtubules and actin in mechanotransduction that contributes to mechanosensitive cell adhesion and migration. (
  • However, data presented support an alternative model in which microtubules transport virions to the cell surface and actin tails form beneath cell-associated enveloped virus (CEV) particles at the cell surface. (
  • Thus, VV is unique in using both microtubules and actin filaments for egress. (
  • This effect is actin independent, but microtubule dependent. (
  • Microtubule and actin differentially regulate synaptic vesicle cycling to maintain high-frequency neurotransmission. (
  • In addition to their structural support role, microtubules also serve as a highway system along which organelles can be transported with the aid of motor proteins. (
  • The motor proteins involved in organelle transport operate by altering their three-dimensional conformation using adenosine triphosphate ( ATP ) as fuel to move back and forth along a microtubule. (
  • Similar to other major cytoskeletons, the microtubules have proteins bound to them. (
  • Examples of proteins that bind to microtubules are motor proteins (e.g. kinesin and dynein), severing proteins (e.g. katanin), and other regulatory proteins. (
  • This method can be applied to study the interaction of proteins that show disorder and/or bind in a nonregular fashion to microtubules. (
  • In addition to the presence of microtubule-associated proteins important determinants of microtubule (MT) function are a multitude of post-translational modifications of the microtubule filament (MT-PTMs). (
  • Kinesins are a diverse superfamily of motor proteins that drive organelles and other microtubule-based movements in eukaryotic cells. (
  • The similarity of carbon nanotubes to microtubules suggests a potential to interact with cellular biomolecules, such as the mitotic spindle, as well as the motor proteins that separate the chromosomes during cell division. (
  • Microtubules re-oriented by the molecular motors can form far-from-equilibrium cell-scale structures, such as the mitotic spindle apparatus. (
  • The nanotube bundles are similar to the potential of nanotubes to induce genetic damage size of microtubules that form the mitotic spindle in normal lung cells, cultured primary and immor- and may be incorporated into the mitotic spindle talized human airway epithelial cells were apparatus. (
  • demonstrate dynein's role in ensuring mechanical force balance in the spindle through its ability to slide antiparallel microtubules towards each other as the spindle elongates in the opposite direction. (
  • In the second part of this study, we consider molecular motors which can push apart antiparallel microtubules and cluster parallel ones. (
  • We argue growing asters recognize each other by interaction between antiparallel microtubules at the mutual boundary, and discuss models for molecular organization of interaction zones. (
  • Because the two ends of a microtubule are not the same, however, the rate at which growth or depolymerization occurs at each pole is different. (
  • Microtubule depolymerization restored LV contractile function both in vivo and in vitro. (
  • For example, salt stress induces microtubules to undergo a process of depolymerization-repolymerization, which is necessary for Arabidopsis seedlings to survive under these conditions. (
  • Paclitaxel blocks microtubule depolymerization thereby stabilizing microtubules and suppressing cell proliferation and other cellular processes. (
  • For instance, the microtubule network interconnects the Golgi apparatus with the plasma membrane to guide secretory vesicles for export, and also transports mitochondria back and forth in the cytoplasm. (
  • The Giardia 's ventral adhesive disk resembles a suction cup, where overlapping microtubules in the cytoplasm form a number-6-shaped figure. (
  • Martins, G. G. & Kolega, J. A role for microtubules in endothelial cell protrusion in three‐dimensional matrices. (
  • Using flat and nanotextured substrates with variable architectures and stiffness, we show that CG sensing is regulated by substrate stiffness and define a mechanical role for microtubules and actomyosin-microtubule interactions during CG sensing. (
  • show that the mechanical properties of aligned extracellular matrix environments influence invasive cell behavior and define a mechanical role for microtubules and actomyosin-microtubule interactions during sensing of contact guidance cues that arise from aligned extracellular matrix. (
  • Ciliary inhibition and axonemal microtubule alterations in freshwater mussels. (
  • The length of microtubules in the cell varies between 200 nanometers and 25 micrometers, depending upon the task of a particular microtubule and the state of the cell's life cycle. (
  • Consequently, simple properties, such as the length of microtubules in the spindle or their number, are still unknown for most model organisms. (
  • However, the orphan motor Kif9 participates in a completely novel kinesin activity, one that maintains a connection between the microtubule-organizing center (MTOC) and nucleus during interphase. (
  • We propose an experiment to demonstrate spontaneous ordering and symmetry breaking of kinesin-driven microtubules confined to an optical trap. (
  • The results as presented support a model in which the cytosolic electric fields and ionic currents generated by the neuronal excitations are "projected" onto the CTTs of underlying microtubules thus affecting their regulatory function upon kinesin motion and MAP attachment/detachment. (
  • Plant cells form acentrosomal spindles with microtubules (MTs) converged toward two structurally undefined poles by employing MT minus end-directed Kinesin-14 motors. (
  • A key player in this process is the microtubule-severing enzyme spastin that localizes at the midbody where its activity is crucial to cut microtubules and culminate the cytokinesis. (
  • Possibly, p160ROCK prevents asymmetric microtubule organization required to direct mother centriole migration to the midbody. (
  • Microtubules are also involved in intracellular movement of organelles, secretory vesicles, and other cytoplasmic structures. (
  • The localization of dynein in mitotic cysts suggests spindle orientation is mediated by the microtubule motor cytoplasmic dynein. (
  • Typically, a single microtubule would be a hollow structure comprised of about 13 protofilaments that associate laterally. (
  • Fig. 5: Microtubule acetylation promotes the release of GEF-H1 into the cytosol. (
  • Indirect immunofluorescence showed that the polypeptide was found in interphase as well as mitotic microtubule arrays. (
  • Growth of interphase asters occurs by a mechanism that allows microtubule density at the aster periphery to remain approximately constant as radius increases. (
  • Seetharaman, S. & Etienne-Manneville, S. Microtubules at focal adhesions - a double-edged sword. (
  • In vitro, elles forment des ponts entre les MTs pour les organiser en faisceaux. (
  • Cryo-Electron Tomography of microtubules assembled in vitro from purified components. (
  • One such mechanism established in vitro is densification of the cellular microtubule network, which imposes a viscous load that inhibits cardiocyte contraction. (
  • In vitro microtubule (MT) binding assayed by total internal reflection fluorescence microscopy. (
  • Other natural toxins, such as the colchicine produced by the meadow saffron, destabilize microtubules and hinder their polymerization. (
  • The nonspecific bindings were determined by incubation with unlabeled microtubule targeting agents MPC-6827, HD-800, colchicine, paclitaxel and docetaxel (5.0 mM). (
  • Fig. 1: Integrin-mediated signalling and substrate rigidity regulate microtubule acetylation. (
  • In other systems it has been demonstrated that MT-PTMs regulate mechanical properties of microtubules, flagellar functions (Intraflagellar transport (IFT), motility) and MT-based transport. (
  • Another example is the translocation of vesicles containing neurotransmitters by microtubules to the tips of nerve cell axons. (
  • While investigating the association of cytosolic NDPK with the plasma membrane, we found that another pool of NDPK is bound to membrane vesicles that are associated with microtubules (Mt/Ves). (
  • Since eukaryotic cells greatly depend upon the integrity of microtubules and other cytoskeletal filaments to maintain their structure and essentially to survive, many plants produce natural toxins aimed at disrupting the microtubule network as a means of self-defense. (
  • Particularly in cellular division, the microtubules are a source of spindle fiber s. (
  • The dynamic instability of microtubules (MT) is an essential feature in eukaryotic cells and related to basic cellular processes such as intracellular transport, cell division, migration, or polarization. (
  • however, the long thin tubular-shaped carbon nanotubes have a striking similarity to cellular microtubules. (
  • It is composed of microtubules, elongated tubular macromolecules with a diameter of 25 nm. (
  • Studies in cultured cells revealed that microtubules can be heavily decorated by mutant M1 but not mutant M87. (
  • No cross-reacting material was detected in microtubules isolated from marine molluscs, mammalia brain or mouse B16 cultured cells. (
  • This is performed both in unrestricted chambers to further observe the general swimming pattern, and since trypanosomes must penetrate the vascular system of different host organisms, we would like to investigate the locomotion of individual cells by quantitative tracking experiments (wild type vs. strains with modified microtubule PTMs) in well-controlled microfluidic chambers. (
  • We conclude that TH588 is a microtubule-modulating agent that activates the mitotic surveillance pathway and thus prevents cancer cells from re-entering the cell cycle. (
  • Fig. 3: Microtubule acetylation reorganizes the actomyosin and intermediate filament networks. (
  • In cilia and flagella, microtubules assemble to form a 9+2 arrangement . (
  • The function of NDPK within primary cilia is most likely to regenerate GTP for microtubule turnover and for signaling systems, making it an important contributor to primary cilia structure and function. (
  • From this, the authors concluded that the observed collapse of the spindle post-ablation is partially mediated by active forces from dynein and microtubule polymerization. (
  • Positioning and elongation of the fission yeast spindle by microtubule-based pushing. (
  • CONCLUSIONS: These and additional corroborative data show that increased cardiocyte microtubule network density is an important mechanism for the ventricular contractile dysfunction that develops in large mammals with adult-onset pressure-overload-induced cardiac hypertrophy. (
  • We have defined microtubule polarity and show the + ends of the cortical microtubules to be at the posterior end of the cell. (
  • We also found that NDPK localizes to yet another microtubule-based cell compartment: the sensory primary cilium, an organelle implicated in many signaling pathways. (
  • While extensive studies have focused on the structure of EB1-interacting site at microtubule ends and its role as a molecular platform, the mechanisms involved in the negative regulation of EB1 have only started to emerge and remain poorly understood. (
  • It is believed that different motor types favour formation of distinct patterns: clustering motors control the formation of spindle poles and asters, while microtubule-sliding motors organise antiparallel bundles presenting in the spindle central part. (
  • Probe optimization allowed us to reach 29 ± 11 nm resolution in stimulated emission depletion (STED) microscopy images of the microtubule network in living human fibroblasts. (
  • For the centerline segmentation, we use 3D template matching and exploit knowledge about shape of microtubules and microscopy artifacts to design the templates. (
  • These observations point out a novel concept of "endogenous EB1 antagonists" and emphasize the importance of finely regulating EB1 function at growing microtubule ends. (
  • Microtubule acetylation, in turn, promotes the release of the guanine nucleotide exchange factor GEF-H1 from microtubules to activate RhoA, actomyosin contractility and traction forces. (
  • Fig. 2: Microtubule acetylation tunes cell mechanosensitivity. (
  • Fig. 4: Microtubule acetylation promotes traction force generation and RhoA activation. (
  • Fig. 6: Microtubule acetylation is required for mechanosensitive migration. (
  • Application to living fruit fly ( Drosophila melanogaster ) tissues highlighted two distinct structures: microtubules and tracheoles. (
  • Conclusions drawn from electron tomographic data is currently mostly based on either small samples containing few microtubules or single sections of complex structures. (
  • Mitchell, Kimberly Ann Parrott, "Association of Nucleoside Diphosphate Kinase with Microtubule-Based Structures" (2008). (
  • GRAPHICS] Six new antimitotic diterpenes, 2-7, have been isolated from the Caribbean octocoral Erythropodium caribaeorum, Structural variations encountered in this group of natural products test recently proposed pharmacophore models for microtubule stabilizing compounds. (
  • We also present recent findings that structural MAPs, that have no tip-tracking activity, physically interact with EB1 to prevent its accumulation at microtubule plus ends. (
  • We show that the screened Coulomb interaction between a target CTT and the negatively charged microtubule surface as well as its immediate CTT neighbours results in confinement of the CTT motion within a restricted volume referred to as a thermal cone. (
  • Within the thermal cone the CTT motion is driven by the thermal fluctuations, while outside the thermal cone the CTT interaction energy with its environment is above the thermal energy solely due to repulsion from the negatively charged microtubule surface. (
  • Ray Rappaport spent many years studying microtubule asters, and how they induce cleavage furrows. (