Actomyosin: A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.Myosins: A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.Myosin Type II: The subfamily of myosin proteins that are commonly found in muscle fibers. Myosin II is also involved a diverse array of cellular functions including cell division, transport within the GOLGI APPARATUS, and maintaining MICROVILLI structure.Actins: 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.Myosin Subfragments: Parts of the myosin molecule resulting from cleavage by proteolytic enzymes (PAPAIN; TRYPSIN; or CHYMOTRYPSIN) at well-localized regions. Study of these isolated fragments helps to delineate the functional roles of different parts of myosin. Two of the most common subfragments are myosin S-1 and myosin S-2. S-1 contains the heads of the heavy chains plus the light chains and S-2 contains part of the double-stranded, alpha-helical, heavy chain tail (myosin rod).Tropomyosin: A protein found in the thin filaments of muscle fibers. It inhibits contraction of the muscle unless its position is modified by TROPONIN.Cytokinesis: The process by which the CYTOPLASM of a cell is divided.Adenosine Triphosphatases: 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.Ca(2+) Mg(2+)-ATPaseTroponin: One of the minor protein components of skeletal muscle. Its function is to serve as the calcium-binding component in the troponin-tropomyosin B-actin-myosin complex by conferring calcium sensitivity to the cross-linked actin and myosin filaments.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Heterocyclic Compounds with 4 or More Rings: A class of organic compounds containing four or more ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic.Actin Cytoskeleton: Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.Nonmuscle Myosin Type IIA: A nonmuscle isoform of myosin type II found predominantly in platelets, lymphocytes, neutrophils and brush border enterocytes.Myofibrils: The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .Cytoskeleton: The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.Muscles: Contractile tissue that produces movement in animals.Calmodulin-Binding Proteins: Proteins which bind calmodulin. They are found in many tissues and have a variety of functions including F-actin cross-linking properties, inhibition of cyclic nucleotide phosphodiesterase and calcium and magnesium ATPases.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.GizzardMyosin Light Chains: The smaller subunits of MYOSINS that bind near the head groups of MYOSIN HEAVY CHAINS. The myosin light chains have a molecular weight of about 20 KDa and there are usually one essential and one regulatory pair of light chains associated with each heavy chain. Many myosin light chains that bind calcium are considered "calmodulin-like" proteins.Cell Shape: The quality of surface form or outline of CELLS.Adenosine Triphosphate: 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.Muscle Proteins: The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.Ethenoadenosine Triphosphate: 1,N-6-Ethenoadenosine triphosphate. A fluorescent analog of adenosine triphosphate.Adenosine Diphosphate: Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.Molecular Motor Proteins: 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).Chemical Precipitation: The formation of a solid in a solution as a result of a chemical reaction or the aggregation of soluble substances into complexes large enough to fall out of solution.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Myosin Heavy Chains: The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.Stress Fibers: Bundles of actin filaments (ACTIN CYTOSKELETON) and myosin-II that span across the cell attaching to the cell membrane at FOCAL ADHESIONS and to the network of INTERMEDIATE FILAMENTS that surrounds the nucleus.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Cytoplasmic Streaming: 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.rho-Associated Kinases: A group of intracellular-signaling serine threonine kinases that bind to RHO GTP-BINDING PROTEINS. They were originally found to mediate the effects of rhoA GTP-BINDING PROTEIN on the formation of STRESS FIBERS and FOCAL ADHESIONS. Rho-associated kinases have specificity for a variety of substrates including MYOSIN-LIGHT-CHAIN PHOSPHATASE and LIM KINASES.Kinetics: The rate dynamics in chemical or physical systems.Schizosaccharomyces: A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.Schizosaccharomyces pombe Proteins: 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.Phalloidine: Very toxic polypeptide isolated mainly from AMANITA phalloides (Agaricaceae) or death cup; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage.Troponin I: One of the three polypeptide chains that make up the TROPONIN complex. It inhibits F-actin-myosin interactions.Nonmuscle Myosin Type IIB: A nonmuscle isoform of myosin type II found predominantly in neuronal tissue.Microfilament Proteins: 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.Cell Polarity: 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.Troponin C: One of the three polypeptide chains that make up the TROPONIN complex of skeletal muscle. It is a calcium-binding protein.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Myosin-Light-Chain Kinase: An enzyme that phosphorylates myosin light chains in the presence of ATP to yield myosin-light chain phosphate and ADP, and requires calcium and CALMODULIN. The 20-kDa light chain is phosphorylated more rapidly than any other acceptor, but light chains from other myosins and myosin itself can act as acceptors. The enzyme plays a central role in the regulation of smooth muscle contraction.Contractile Proteins: Proteins which participate in contractile processes. They include MUSCLE PROTEINS as well as those found in other cells and tissues. In the latter, these proteins participate in localized contractile events in the cytoplasm, in motile activity, and in cell aggregation phenomena.Time-Lapse Imaging: Recording serial images of a process at regular intervals spaced out over a longer period of time than the time in which the recordings will be played back.Gastrulation: A process of complicated morphogenetic cell movements that reorganizes a bilayer embryo into one with three GERM LAYERS and specific orientation (dorsal/ventral; anterior/posterior). Gastrulation describes the germ layer development of a non-mammalian BLASTULA or that of a mammalian BLASTOCYST.Protein Binding: 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.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Psoas Muscles: A powerful flexor of the thigh at the hip joint (psoas major) and a weak flexor of the trunk and lumbar spinal column (psoas minor). Psoas is derived from the Greek "psoa", the plural meaning "muscles of the loin". It is a common site of infection manifesting as abscess (PSOAS ABSCESS). The psoas muscles and their fibers are also used frequently in experiments in muscle physiology.Models, Biological: 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.Diacetyl: Carrier of aroma of butter, vinegar, coffee, and other foods.Myosin Type V: A subclass of myosin involved in organelle transport and membrane targeting. It is abundantly found in nervous tissue and neurosecretory cells. The heavy chains of myosin V contain unusually long neck domains that are believed to aid in translocating molecules over large distances.Physarum: A genus of protozoa, formerly also considered a fungus. Characteristics include the presence of violet to brown spores.Isometric Contraction: Muscular contractions characterized by increase in tension without change in length.

Evidence for F-actin-dependent and -independent mechanisms involved in assembly and stability of the medial actomyosin ring in fission yeast. (1/982)

Cell division in a number of eukaryotes, including the fission yeast Schizosaccharomyces pombe, is achieved through a medially placed actomyosin-based contractile ring. Although several components of the actomyosin ring have been identified, the mechanisms regulating ring assembly are still not understood. Here, we show by biochemical and mutational studies that the S.pombe actomyosin ring component Cdc4p is a light chain associated with Myo2p, a myosin II heavy chain. Localization of Myo2p to the medial ring depended on Cdc4p function, whereas localization of Cdc4p at the division site was independent of Myo2p. Interestingly, the actin-binding and motor domains of Myo2p are not required for its accumulation at the division site although the motor activity of Myo2p is essential for assembly of a normal actomyosin ring. The initial assembly of Myo2p and Cdc4p at the division site requires a functional F-actin cytoskeleton. Once established, however, F-actin is not required for the maintenance of Cdc4p and Myo2p medial rings, suggesting that the attachment of Cdc4p and Myo2p to the division site involves proteins other than actin itself.  (+info)

Calculation of a Gap restoration in the membrane skeleton of the red blood cell: possible role for myosin II in local repair. (2/982)

Human red blood cells contain all of the elements involved in the formation of nonmuscle actomyosin II complexes (V. M. Fowler. 1986. J. Cell. Biochem. 31:1-9; 1996. Curr. Opin. Cell Biol. 8:86-96). No clear function has yet been attributed to these complexes. Using a mathematical model for the structure of the red blood cell spectrin skeleton (M. J. Saxton. 1992. J. Theor. Biol. 155:517-536), we have explored a possible role for myosin II bipolar minifilaments in the restoration of the membrane skeleton, which may be locally damaged by major mechanical or chemical stress. We propose that the establishment of stable links between distant antiparallel actin protofilaments after a local myosin II activation may initiate the repair of the disrupted area. We show that it is possible to define conditions in which the calculated number of myosin II minifilaments bound to actin protofilaments is consistent with the estimated number of myosin II minifilaments present in the red blood cells. A clear restoration effect can be observed when more than 50% of the spectrin polymers of a defined area are disrupted. It corresponds to a significant increase in the spectrin density in the protein free region of the membrane. This may be involved in a more complex repair process of the red blood cell membrane, which includes the vesiculation of the bilayer and the compaction of the disassembled spectrin network.  (+info)

Ca2+ and cross-bridge-induced changes in troponin C in skinned skeletal muscle fibers: effects of force inhibition. (3/982)

Changes in skeletal troponin C (sTnC) structure during thin filament activation by Ca2+ and strongly bound cross-bridge states were monitored by measuring the linear dichroism of the 5' isomer of iodoacetamidotetramethylrhodamine (5'IATR), attached to Cys98 (sTnC-5'ATR), in sTnC-5'ATR reconstituted single skinned fibers from rabbit psoas muscle. To isolate the effects of Ca2+ and cross-bridge binding on sTnC structure, maximum Ca2+-activated force was inhibited with 0.5 mM AlF4- or with 30 mM 2,3 butanedione-monoxime (BDM) during measurements of the Ca2+ dependence of force and dichroism. Dichroism was 0.08 +/- 0.01 (+/- SEM, n = 9) in relaxing solution (pCa 9.2) and decreased to 0.004 +/- 0.002 (+/- SEM, n = 9) at pCa 4.0. Force and dichroism had similar Ca2+ sensitivities. Force inhibition with BDM caused no change in the amplitude and Ca2+ sensitivity of dichroism. Similarly, inhibition of force at pCa 4.0 with 0.5 mM AlF4- decreased force to 0.04 +/- 0.01 of maximum (+/- SEM, n = 3), and dichroism was 0.04 +/- 0.03 (+/- SEM, n = 3) of the value at pCa 9.2 and unchanged relative to the corresponding normalized value at pCa 4.0 (0.11 +/- 0.05, +/- SEM; n = 3). Inhibition of force with AlF4- also had no effect when sTnC structure was monitored by labeling with either 5-dimethylamino-1-napthalenylsulfonylaziridine (DANZ) or 4-(N-(iodoacetoxy)ethyl-N-methyl)amino-7-nitrobenz-2-oxa-1,3-diazole (NBD). Increasing sarcomere length from 2.5 to 3.6 microm caused force (pCa 4.0) to decrease, but had no effect on dichroism. In contrast, rigor cross-bridge attachment caused dichroism at pCa 9.2 to decrease to 0.56 +/- 0.03 (+/- SEM, n = 5) of the value at pCa 9. 2, and force was 0.51 +/- 0.04 (+/- SEM, n = 6) of pCa 4.0 control. At pCa 4.0 in rigor, dichroism decreased further to 0.19 +/- 0.03 (+/- SEM, n = 6), slightly above the pCa 4.0 control level; force was 0.66 +/- 0.04 of pCa 4.0 control. These results indicate that cross-bridge binding in the rigor state alters sTnC structure, whereas cycling cross-bridges have little influence at either submaximum or maximum activating [Ca2+].  (+info)

Rational analyses of organelle trajectories in tobacco pollen tubes reveal characteristics of the actomyosin cytoskeleton. (4/982)

To gain insight into the characteristics of organelle movement and the underlying actomyosin motility system in tobacco pollen tubes, we collected data points representing sequential organelle positions in control and cytochalasin-treated cells, and in a sample of extruded cytoplasm. These data were utilized to reconstruct approximately 900 tracks, representing individual organelle movements, and to produce a quantitative analysis of the movement properties, supported by statistical tests. Each reconstructed track appeared to be unique and to show irregularities in velocity and direction of movement. The regularity quotient was near 2 at the tip and above 3 elsewhere in the cell, indicating that movement is more vectorial in the tube area. Similarly, the progressiveness ratio showed that there were relatively more straight trajectories in the tube region than at the tip. Consistent with these data, arithmetical dissection revealed a high degree of randomlike movement in the apex, lanes with tip-directed movement along the flanks, and grain-directed movement in the center of the tube. Intercalated lanes with bidirectional movement had lower organelle velocity, suggesting that steric hindrance plays a role. The results from the movement analysis indicate that the axial arrangement of the actin filaments and performance of the actomyosin system increases from tip to base, and that the opposite polarity of the actin filaments in the peripheral (+-ends of acting filaments toward the tip) versus the central cytoplasm (+-ends of actin filaments toward to the grain) is installed within a few minutes in these tip-growing cells.  (+info)

Alterations of cross-bridge kinetics in human atrial and ventricular myocardium. (5/982)

CONDENSED ABSTRACT: We analyzed actomyosin cross-bridge kinetics in human atrial and ventricular muscle strip preparations by using sinusoidal length changes from 0.1 to 60 Hz. The minimum stiffness frequency was higher in atrial than in ventricular human myocardium and lower in failing than in non-failing left ventricular human myocardium. beta-Adrenergic stimulation increased the minimum stiffness frequency by 18 +/- 3% (p < 0.05). Cross-bridge kinetics are temperature-dependent, with a Q10 of at least 2.7. BACKGROUND: Dynamic stiffness measurements have revealed acute and chronic alterations of actomyosin cross-bridge kinetics in cardiac muscles of a variety of different animal species. We studied dynamic stiffness in right atrial and left ventricular preparations of non-failing and failing human hearts and tested the influence of the temperature and beta-adrenergic stimulation on cross-bridge kinetics. METHODS AND RESULTS: Muscle strips were prepared from right atria and left ventricles from human non-failing and failing hearts. After withdrawal of calcium, steady contracture tension was induced by the addition of 1.5 mM barium chloride. Sinusoidal length oscillations of 1% muscle length were applied, with a frequency spectrum of between 0.1 and 60 Hz. Dynamic stiffness was calculated from the length change and the corresponding force response amplitude. The specific minimum stiffness frequency, which indicates the interaction between cross-bridge recruitment and cross-bridge cycling dynamics, was analyzed for each condition: (1) The minimum stiffness frequency was 0.78 +/- 0.04 Hz in left ventricular myocardium and 2.80 +/- 0.31 Hz in right atrial myocardium (p < 0.01) at 27 degrees C. (2) The minimum stiffness frequency was 41% higher in non-failing compared to failing left ventricular human myocardium. (3) Over a wide range of experimental temperatures, the minimum stiffness frequency changed, with a Q10 of at least 2.7. (4) beta-Adrenergic stimulation significantly (p < 0.05) increased the minimum stiffness to 18 +/- 3% higher frequencies and significantly (p < 0.05) lowered contracture tension by 7 +/- 1%. CONCLUSIONS: The contractility of human heart muscle is not only regulated by excitation-contraction coupling but also by modulation of intrinsic properties of the actomyosin system. Acute and chronic alterations of cross-bridge kinetics have been demonstrated, which play a significant role in the physiology and pathophysiology of the human heart.  (+info)

Amphidinolide B, a powerful activator of actomyosin ATPase enhances skeletal muscle contraction. (6/982)

Amphidinolide B caused a concentration-dependent increase in the contractile force of skeletal muscle skinned fibers. The concentration-contractile response curve for external Ca2+ was shifted to the left in a parallel manner, suggesting an increase in Ca2+ sensitivity. Amphidinolide B stimulated the superprecipitation of natural actomyosin. The maximum response of natural actomyosin to Ca2+ in superprecipitation was enhanced by it. Amphidinolide B increased the ATPase activity of myofibrils and natural actomyosin. The ATPase activity of actomyosin reconstituted from actin and myosin was enhanced in a concentration-dependent manner in the presence or absence of troponin-tropomyosin complex. Ca2+-, K+-EDTA- or Mg2+-ATPase of myosin was not affected by amphidinolide B. These results suggest that amphidinolide B enhances an interaction of actin and myosin directly and increases Ca2+ sensitivity of the contractile apparatus mediated through troponin-tropomyosin system, resulting in an increase in the ATPase activity of actomyosin and thus enhances the contractile response of myofilament.  (+info)

Backward movements of cross-bridges by application of stretch and by binding of MgADP to skeletal muscle fibers in the rigor state as studied by x-ray diffraction. (7/982)

The effects of the applied stretch and MgADP binding on the structure of the actomyosin cross-bridges in rabbit and/or frog skeletal muscle fibers in the rigor state have been investigated with improved resolution by x-ray diffraction using synchrotron radiation. The results showed a remarkable structural similarity between cross-bridge states induced by stretch and MgADP binding. The intensities of the 14.4- and 7.2-nm meridional reflections increased by approximately 23 and 47%, respectively, when 1 mM MgADP was added to the rigor rabbit muscle fibers in the presence of ATP-depletion backup system and an inhibitor for muscle adenylate kinase or by approximately 33 and 17%, respectively, when rigor frog muscle was stretched by approximately 4.5% of the initial muscle length. In addition, both MgADP binding and stretch induced a small but genuine intensity decrease in the region close to the meridian of the 5.9-nm layer line while retaining the intensity profile of its outer portion. No appreciable influence was observed in the intensities of the higher order meridional reflections of the 14.4-nm repeat and the other actin-based reflections as well as the equatorial reflections, indicating a lack of detachment of cross-bridges in both cases. The changes in the axial spacings of the actin-based and the 14.4-nm-based reflections were observed and associated with the tension change. These results indicate that stretch and ADP binding mediate similar structural changes, being in the correct direction to those expected for that the conformational changes are induced in the outer portion distant from the catalytic domain of attached cross-bridges. Modeling of conformational changes of the attached myosin head suggested a small but significant movement (about 10-20 degrees) in the light chain-binding domain of the head toward the M-line of the sarcomere. Both chemical (ADP binding) and mechanical (stretch) intervensions can reverse the contractile cycle by causing a backward movement of this domain of attached myosin heads in the rigor state.  (+info)

The translation in vitro of mRNA from developing cysts of Artemia salina. (8/982)

Successive stages in the development of the brine shrimp cyst were used as a model for studying differentiation at the level of mRNA transcription and translation. The poly (A)-containing mRNA from dormant cysts and free-swimming larvae (nauplii) was found to be efficiently translated in a wheat-germ cell-free system, and electrophoretic patterns of translation products in vitro resembled those of the endogenous proteins extracted from the equivalent developmental stages. Each stage, however, exhibits a characteristic protein pattern. Two low-molecular-weight proteins prominent in the cyst disappeared almost completely in the nauplius stage, whereas the proportion of actin increased 3-fold. Parallel patterns were observed upon translation in vitro of the respective mRNA preparations. The percentage of the acidic protein, tubulin, decreased somewhat during development.  (+info)

TY - JOUR. T1 - Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor. AU - Takano, Mitsunori. AU - Terada, Tomoki P.. AU - Sasai, Masaki. PY - 2010/4/27. Y1 - 2010/4/27. N2 - The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle contraction, converting chemical energy into mechanical work. Although recent single molecule and structural studies have shed new light on the energy-converting mechanism, the physical basis of the molecular-level mechanism remains unclear because of the experimental limitations. To provide a clue to resolve the controversy between the lever-arm mechanism and the Brownian ratchet-like mechanism, we here report an in silico single molecule experiment of an actomyosin motor.When we placed myosin on an actin filament and allowed myosin to move along the filament, we found that myosin exhibits a unidirectional Brownian motion along the filament. This ...
We have investigated how cell contractility and adhesion are functionally integrated during epithelial morphogenesis. To this end, we have analysed the role of α-Catenin, a key molecule linking E-Cadherin-based adhesion and the actomyosin cytoskeleton, during Drosophila embryonic dorsal closure, by studying a newly developed allelic series. We find that α-Catenin regulates pulsatile apical contraction in the amnioserosa, the main force-generating tissue driving closure of the embryonic epidermis. α-Catenin controls actomyosin dynamics by stabilising and promoting the formation of actomyosin foci, and also stabilises DE-Cadherin (Drosophila E-Cadherin, also known as Shotgun) at the cell membrane, suggesting that medioapical actomyosin contractility regulates junction stability. Furthermore, we uncover a genetic interaction between α-Catenin and Vinculin, and a tension-dependent recruitment of Vinculin to amniosersoa apical cell membranes, suggesting the existence of a mechano-sensitive module ...
TY - JOUR. T1 - Mechanical measurements of single actomyosin motor force. AU - Miyata, H.. AU - Yoshikawa, H.. AU - Hakozaki, H.. AU - Suzuki, N.. AU - Furuno, Taiji. AU - Ikegami, A.. AU - Kinosita, K.. AU - Nishizaka, T.. AU - Ishiwata, S.. AU - Driezen, P.. AU - Mehta, A.. PY - 1995. Y1 - 1995. N2 - To elucidate the mechanism of force generation by actomyosin motor, a measuring system was constructed, in which an in vitro motility assay was combined with an optical trapping technique. An actin filament of several μm long was attached to a gelsolin-coated polystyrene bead, and was allowed to interact with a small number (~1/1-μm actin filament) of rabbit skeletal heavy meromyosin (an active subfragment of myosin) molecules bound to a nitrocellulose-coated coverglass. The bead position was determined at 33-ms intervals. We measured the force generation event at relatively low (100-400 nM) ATP concentration so that the occurrence of individual force generation events could be detected with our ...
Bundles of filaments and motors are central to contractility in cells. The classic example is striated muscle, where actomyosin contractility is mediated by highly organized sarcomeres which act as fundamental contractile units. However, many contractile bundles in vivo and in vitro lack sarcomeric organization. Here we propose a model for how contractility can arise in bundles without sarcomeric organization and validate its predictions with experiments on a reconstituted system. In the model, internal stresses in frustrated arrangements of motors with diverse velocities cause filaments to buckle, leading to overall shortening. We describe the onset of buckling in the presence of stochastic motor head detachment and predict that buckling-induced contraction occurs in an intermediate range of motor densities. We then calculate the size of the contractile units associated with this process. Consistent with these results, our reconstituted actomyosin bundles show contraction at relatively high ...
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Oxidative stress-induced neuronal apoptosis plays an important role in the progression of central nervous system (CNS) diseases. In our study, when neuronal cells were exposed to hydrogen peroxide (H2O2), an exogenous oxidant, cell apoptosis was observed with typical morphological changes including membrane blebbing, neurite retraction and cell contraction. The actomyosin system is considered to be responsible for the morphological changes, but how exactly it regulates oxidative stress-induced neuronal apoptosis and the distinctive functions of different myosin II isoforms remain unclear. We demonstrate that myosin IIA was required for neuronal contraction, while myosin IIB was required for neuronal outgrowth in normal conditions. During H2O2-induced neuronal apoptosis, myosin IIA, rather than IIB, interacted with actin filaments to generate contractile forces that leaded to morphological changes. Moreover, myosin IIA knockout using CRISPR/Cas9 reduced H2O2-induced neuronal apoptosis and the associated
During inversion of a Volvox embryo, a series of cell shape changes causes the multicellular sheet to bend outward, and propagation of the bend from the anterior to the posterior pole eventually results in an inside-out spherical sheet of cells. We use fluorescent and electron microscopy to study the behavior of the cytoskeleton in cells undergoing shape changes. Microtubules are aligned parallel to the cells long axis and become elongated in the bend. Myosin and actin filaments are arrayed perinuclearly before inversion. In inversion, actin and myosin are located in a subnuclear position throughout the uninverted region but this localization is gradually lost towards the bend. Actomyosin inhibitors cause enlargement of the embryo. The bend propagation is inhibited halfway and, as a consequence, the posterior hemisphere remains uninverted. The arrested posterior hemisphere will resume and complete inversion even in the presence of an actomyosin inhibitor if the anterior hemisphere is removed ...
The replacement of cells is a common strategy during animal development. In the Drosophila pupal abdomen, larval epidermal cells (LECs) are replaced by adult progenitor cells (histoblasts). Previous work showed that interactions between histoblasts and LECs result in apoptotic extrusion of LECs during early pupal development. Extrusion of cells is closely preceded by caspase activation and is executed by contraction of a cortical actomyosin cable. Here, we identify a population of LECs that extrudes independently of the presence of histoblasts during late pupal development. Extrusion of these LECs is not closely preceded by caspase activation, involves a pulsatile medial actomyosin network, and correlates with a developmental time period when mechanical tension and E-cadherin turnover at adherens junctions is particularly high. Our work reveals a developmental switch in the cell extrusion mechanism that correlates with changes in tissue mechanical properties. ...
La morfogènesi crea una plètora de formes complexes en animals i plantes. Hem consagrat aquest treball a lestudi de la involució del cap (head involution HI) de Drosophila, un procés embriogenètic tardiu, que implica un complet rearranjament dels teixits del cap, així com la internalització del cervell i la propagació de lepidermis. Mostrem, pel primer cop, la cinètica completa de HI amb una alta resolució espacial i temporal. Describim els moviments que porten a la internalització del cervell de lembrió, així com el seu "sculpting" per apoptosi i leliminació de cèl.lules pels hemòcits. Seguidament, hem enfocat lestudi en la progressió de lepidermis sobre el cap de lembrió, essent aquest un esdeveniment que es pot dividir en dues fases: rodolament i lliscament. Mostrem que totes dues fases son impulsades per un cable dactomyosina. També mostrem que la propagació de lepidermis es troba espacialment controlada, tenint aquest control com a resultat la formació de ...
Rho GTPases are molecular switches that regulate many aspects of cell physiology. A number of Rho GTPases are essential for the formation of new vessels from pre-existing ones, a process known as angiogenesis. RhoJ/TCL belongs to the Cdc42 subfamily of Rho GTPases. Previous bioinformatic and primary cell line analyses identified RhoJ as being highly expressed in endothelial cells. The aim of this project was to investigate the expression pattern and endothelial function of RhoJ, particularly in the processes necessary for angiogenesis. Silencing RhoJ with siRNA impaired tube formation and migration. On the cellular level, RhoJ knockdown increased focal adhesions, actin stress fibres and collagen gel contraction, suggesting increased actomyosin contractility. Pharmacological inhibition of ROCK and myosin II, two regulators of actomyosin contractility, restored motility and tube formation after RhoJ knockdown. RhoJ localised to blood vessels of developing mice and in various human normal and ...
The wound healing response is an essential mechanism to maintain the integrity of epithelia and protect all organisms from the surrounding milieu. In the purse-string mechanism of wound closure, an injured epithelial sheet cinches its hole closed via an intercellular contractile actomyosin cable. This process is conserved across species and utilized by both embryonic as well as adult tissues, but remains poorly understood at the cellular level. In an effort to identify new players involved in purse-string wound closure a wounding strategy suitable for screening large numbers of Drosophila embryos was developed. Using this methodology, wound healing defects were observed in Jun-related antigen (encoding DJUN) and scab (encoding Drosophila alphaPS3 integrin) mutants and a forward genetics screen was performed on the basis of insertional mutagenesis by transposons that led to the identification of 30 lethal insertional mutants with defects in embryonic epithelia repair. One of the mutants ...
Collective cell migration is involved in development, wound healing and metastasis. In the Drosophila ovary, border cells (BC) form a small cluster that migrates collectively through the egg chamber. To achieve directed motility, the BC cluster coordinates the formation of protrusions in its leader cell and contractility at the rear. Restricting protrusions to leader cells requires the actin and plasma membrane linker Moesin. Herein, we show that the Ste20-like kinase Misshapen phosphorylates Moesin in vitro and in BC. Depletion of Misshapen disrupts protrusion restriction, thereby allowing other cells within the cluster to protrude. In addition, we show that Misshapen is critical to generate contractile forces both at the rear of the cluster and at the base of protrusions. Together, our results indicate that Misshapen is a key regulator of BC migration as it coordinates two independent pathways that restrict protrusion formation to the leader cells and induces contractile forces.. ...
Cell migration is essential for embryogenesis, wound healing, immune surveillance, and progression of diseases, such as cancer metastasis. For the migration to occur, cellular structures such as actomyosin cables and cell-substrate adhesion clusters must interact. As cell trajectories exhibit a random character, so must such interactions. Furthermore, migration often occurs in a crowded environment, where the collision outcome is deter- mined by altered regulation of the aforementioned structures. In this work, guided by a few fundamental attributes of cell motility, we construct a minimal stochastic cell migration model from ground-up. The resulting model couples a deterministic actomyosin contrac- tility mechanism with stochastic cell-substrate adhesion kinetics, and yields a well-defined piecewise deterministic process. The signaling pathways regulating the contractility and adhesion are considered as well. The model is extended to include cell collectives. Numer- ical simulations of single ...
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apical junction complex, cytoskeleton, structural constituent of cytoskeleton, actomyosin structure organization, apical constriction, cellular protein localization, regulation of actin filament-based process
... : actomyosin gels interact in a THRESHOLD manner. For details see the following paper: V.V.Matveev. Evidence of a new type of protein-protein interaction: desensitized actomyosin blocks Ca2+-sensitivity of the natural one. A possible model for an intracellular signalling system related to actin filaments. Physiological Chemistry Physics & Medical NMR, 32: 167-179, 2000. ABSTRACT see here: http://members.nbci.com/vm_spb/actomyosin/signal.htm Sent via Deja.com http://www.deja.com/ Before you buy ...
The Genetics Society of America (GSA), founded in 1931, is the professional membership organization for scientific researchers and educators in the field of genetics. Our members work to advance knowledge in the basic mechanisms of inheritance, from the molecular to the population level.. Online ISSN: 1943-2631. ...
Polyclonal antibody for PPP1R12A detection. Host: Rabbit.Size: 100μg/vial. Tested applications: Flow Cytometry. Reactive species: Human. PPP1R12A information: Molecular Weight: 115281 MW; Subcellular Localization: Cytoplasm . Along actomyosin filaments an
A wide variety of cell types exhibit substrate topography-based behavior, also known as contact guidance. However, the precise cellular mechanisms underlying this process are still unknown. In this study, we investigated contact guidance by studying the reaction of human endothelial cells (ECs) to well-defined microgroove topographies, both during and after initial cell spreading. As the cytoskeleton plays a major role in cellular adaptation to topographical features, two methods were used to perturb cytoskeletal structures. Inhibition of actomyosin contractility with the chemical inhibitor blebbistatatin demonstrated that initial contact guidance events are independent of traction force generation. However, cell alignment to the grooved substrate was altered at later time points, suggesting an initial passive phase of contact guidance, followed by a contractility-dependent active phase that relies on mechanosensitive feedback. The actin cytoskeleton was also perturbed in an indirect manner ...
Kumar, Abhishek and Maitra, Ananyo and Sumit, Madhuresh and Ramaswamy, Sriram and Shivashankar, G. V. (2014) Actomyosin contractility rotates the cell nucleus. In: SCIENTIFIC REPORTS, 4 . ...
... system based on actin cytoskeleton. V.V.Matveev. Evidence of a new type of protein-protein interaction: desensitized actomyosin blocks Ca2+-sensitivity of the natural one. A possible model for an intracellular signalling system related to actin filaments. Physiological Chemistry Physics & Medical NMR, 32: 167-179, 2000. ABSTRACT see here: http://members.nbci.com/vm_spb/actomyosin/signal.htm Sent via Deja.com http://www.deja.com/ Before you buy ...
Abstract: We investigate the effect of stress fluctuations on the stochastic dynamics of an inclusion embedded in a viscous gel. We show that, in non-equilibrium systems, stress fluctuations give rise to an effective attraction towards the boundaries of the confining domain, which is reminiscent of an active Casimir effect. We apply this generic result to the dynamics of deformations of the cell nucleus and we demonstrate the appearance of a fluctuation maximum at a critical level of activity, in agreement with recent experiments [E. Makhija, D. S. Jokhun, and G. V. Shivashankar, Proc. Natl. Acad. Sci. U.S.A. 113, E32 (2016 ...
S pombe Rng2 protein: a component of the actomyosin ring and the spindle pole body; homologous to S cerevisiae IQG1 protein; amino acid sequence in first source
What is actomyosin cortex? The cell cortex is a thin (~0.1 µm thick) network of actin filaments and actin-binding proteins that underlies the plasma membrane in most eukaryotic cells. The cortex is the main determinant of cell shape and therefore plays a fundamental role in processes such as cell division, migration, and tissue morphogenesis. Despite…
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The terminal web is a zone or a region located at the base of the microvilli in certain specialized epithelial cells (such as intestinal epithelial cells). The name is derived from the web (meshwork) of microfilaments that compose this region. The web of microfilaments is from the bundles of apical filaments at the core of a microvillus as well as from adherens junctions in myosin and in other proteins characteristic of an actomyosin motor system. The actin filaments in the terminal web are stabilized by spectrin. They anchor the terminal web to the apical cell membrane. The contractile ability of the terminal web is due to the presence of myosin II and tropomyosin. It is observed that the contraction at the terminal web results in the decrease in the diameter of the apex of the cell. This, in turn, causes the microvilli to spread apart, which is essential during absorption.1,2,3 ...
Isoform 2 and isoform 3 can activate the C-terminal fragment (CTF) of ERBB4 (isoform 3).. Transcriptional regulator which can act both as a coactivator and a corepressor and is the critical downstream regulatory target in the Hippo signaling pathway that plays a pivotal role in organ size control and tumor suppression by restricting proliferation and promoting apoptosis (PubMed:17974916, PubMed:18280240, PubMed:18579750, PubMed:21364637, PubMed:30447097). The core of this pathway is composed of a kinase cascade wherein STK3/MST2 and STK4/MST1, in complex with its regulatory protein SAV1, phosphorylates and activates LATS1/2 in complex with its regulatory protein MOB1, which in turn phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ (PubMed:18158288). Plays a key role in tissue tension and 3D tissue shape by regulating cortical actomyosin network formation. Acts via ARHGAP18, a Rho GTPase activating protein that suppresses F-actin polymerization (PubMed:25778702). Plays a key role to ...
TY - JOUR. T1 - Cytokinesis in development and disease. T2 - Variations on a common theme. AU - Li, R.. PY - 2007/12. Y1 - 2007/12. N2 - Cytokinesis is a crucial step in cell proliferation, and remarkably, it is also an important mechanism for developmental regulation in the generation of diverse cell types in eukaryotic organisms. Successful cytokinesis relies on the assembly and activation of an actomyosin-based contractile ring and membrane deposition/fusion in a spatially and temporally precise manner. As such, the molecular pathways governing cytokinesis are highly complex, involving a large number of components forming intricate interactive networks. The complexity of this system, however, may have also provided a rich platform for evolutionary tinkering to achieve specific morphogenetic and developmental outcomes. Furthermore, failed or altered cytokinesis appears to contribute to the development of cancer in unexpected ways.. AB - Cytokinesis is a crucial step in cell proliferation, ...
Parisa Kakanj, the author of the study, examined the skin of larvae of the fruit fly Drosophila melanogaster. These flies serve as models for diabetes, because insulin metabolism has been strongly conserved over the course of evolution, meaning that flies and mammals are very similar in this respect. Using a precision laser, Kakanj removed a cell from the outermost skin layer of fruit fly larvae and then observed what happens in the neighbouring cells live under the microscope.. "Immediately after a skin injury, the neighbouring cells respond by forming an actomyosin cable," Kakanj explains. The cable consists of proteins that otherwise occur in muscle fibres, where they are responsible for muscular contraction. After an injury, the cable forms a contractile ring around the wound. It then contracts, sealing off the gap caused by the wound. "However, if insulin metabolism is impaired, as in our genetically modified flies, the cable is weaker and forms much later. This results in incomplete or ...
Epithelial cells maintain an essential barrier despite continuously undergoing mitosis and apoptosis. Biological and biophysical mechanisms have evolved to remove dying cells while maintaining that barrier. Cell extrusion is thought to be driven by a multicellular filamentous actin ring formed by neighbouring cells, the contraction of which provides the mechanical force for extrusion, with little or no contribution from the dying cell. Here, we use live confocal imaging, providing time-resolved three-dimensional observations of actomyosin dynamics, to reveal new mechanical roles for dying cells in their own extrusion from monolayers. Based on our observations, the clearance of dying cells can be subdivided into two stages. The first, previously unidentified, stage is driven by the dying cell, which exerts tension on its neighbours through the action of a cortical contractile F-actin and myosin ring at the cell apex. The second stage, consistent with previous studies, is driven by a multicellular ...
Malignancy is associated with altered expression of glycans and glycoproteins that contribute to the cellular glycocalyx. We constructed a glycoprotein expression signature, which revealed that metastatic tumors upregulate expression of bulky glycoproteins. A computational model predicted that these glycoproteins would influence transmembrane receptor spatial organization and function. We tested this prediction by investigating whether a bulky glycocalyx promotes a tumor phenotype by increasing integrin adhesion and signaling. Data revealed that a bulky glycocalyx facilitates integrin clustering by funneling active integrins into adhesions and altering integrin state by applying tension to matrix-bound integrins, independent of actomyosin contractility. Expression of large tumor-associated glycoproteins in non-transformed mammary cells promoted focal adhesion assembly and facilitated integrin-dependent growth factor signaling to support cell growth and survival. Clinical studies revealed that ...
Myosin Binding Protein-C (MyBP-C) comprises a family of accessory proteins that includes the cardiac, slow skeletal, and fast skeletal isoforms. The three isoforms share structural and sequence homology, and localize at the C-zone of the sarcomeric A-band where they interact with thick and thin filaments to regulate the cycling of actomyosin crossbridges. The cardiac isoform, encoded by MYBPC3, has been extensively studied over the last several decades due to its high mutational rate in congenital hypertrophic and dilated cardiomyopathy. It is only recently, however, that the MYBPC1 gene encoding the slow skeletal isoform (sMyBP-C) has gained attention. Accordingly, during the last five years it has been shown that MYBPC1 undergoes extensive exon shuffling resulting in the generation of multiple slow variants, which are co-expressed in different combinations and amounts in both slow and fast skeletal muscles. The sMyBP-C variants are subjected to PKA- and PKC-mediated phosphorylation in constitutive and
Summary. QuimP is software for tracking cellular shape changes and dynamic distributions of fluorescent reporters at the cell membrane. QuimPs unique selling point is the possibility to aggregate data from many cells in form of spatio-temporal maps of dynamic events, independently of cell size and shape. QuimP has been successfully applied to address a wide range of problems related to cell movement in many different cell types. Introduction. In transmembrane signalling the cell membrane plays a fundamental role in localising intracellular signalling components to specific sites of action, for example to reorganise the actomyosin cortex during cell polarisation and locomotion. The localisation of different components can be directly or indirectly visualised using fluorescence microscopy, for high-throughput screening commonly in 2D. A quantitative understanding demands segmentation and tracking of whole cells and fluorescence signals associated with the moving cell boundary, for example those ...
Working model of vertex ring assembly. See text for details. Solid black arrows indicate a strict hierarchical requirement for vertex enrichment. Dotted arrows
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Function VisibleCells(Rng As Range) As Variant VisibleCells This function returns an array equal in dimension to the input parameter Rng containing 1s and 0s indicating whether a cells within Rng is visible. Note that we use 1 to indicate True rather than VBAs True value (which equals -1). If Rng has more than one area (discontiguous ranges), the function returns a #REF error. Dim R As Range Dim Arr() As Integer Dim RNdx As Long Dim CNdx As Long Ensure a valid range. If Rng.Areas.Count > 1 Then VisibleCells = CVErr(xlErrRef) Exit Function End If Size the return array to equal the Rng parameter. ReDim Arr(1 To Rng.Rows.Count, 1 To Rng.Columns.Count) For RNdx = 1 To Rng.Rows.Count For CNdx = 1 ...
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In this study we could show that formation of retraction septa in U. maydis infectious hyphae depends on the diaphanous-related formin Drf1. Drf1 acts as an effector of the small GTPase Cdc42 and is together with the Cdc42-GEF Don1 and the Ste20-like kinase Don3 required for the formation of a contractile actomyosin ring during septation. Remarkably, non-septated infectious hyphae, that have exceeded a certain length, are unable to form appressoria, while short hyphae lacking retraction septa form appressoria. This led to a significant reduction in the formation of functional infection structures and thus explains the attenuated virulence of drf1, don1 and don3 mutants.. Formins are major players in actin organisation. The genome of U. maydis encodes along with the diaphanous-related formin Drf1, a second formin, Srf1, which belongs to the subfamily of SepA-related formins (MIPS U. maydis data base) [29]. While srf1 is an essential gene (B. Sandrock, unpublished data), we found that drf1 ...
For the survival of both the parent and the progeny, it is imperative that the process of their physical division (cytokinesis) be precisely coordinated with progression through the mitotic cell cycle. Recent studies in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe are beginning to unravel the nature of the links between cytokinesis and the nuclear division cycle. The cyclin-dependent kinases and a novel surveillance mechanism that monitors cytokinesis and/or morphogenesis appear to play important regulatory roles in forging these links. It is becoming increasingly clear that the inactivation of the mitosis-promoting cyclin-dependent kinase, which marks the completion of the nuclear division cycle, is essential for actomyosin ring constriction and division septum assembly in both yeasts. Additionally, the spindle pole bodies are emerging as important transient locale for proteins that might play a key role in coupling the completion of mitosis to the ...
As a member of the wwPDB, the RCSB PDB curates and annotates PDB data according to agreed upon standards. The RCSB PDB also provides a variety of tools and resources. Users can perform simple and advanced searches based on annotations relating to sequence, structure and function. These molecules are visualized, downloaded, and analyzed by users who range from students to specialized scientists.
Actin- and myosin-binding protein implicated in the regulation of actomyosin interactions in smooth muscle and nonmuscle cells (could act as a bridge between myosin and actin filaments). Stimulates actin binding of tropomyosin which increases the stabilization of actin filament structure. In muscle tissues, inhibits the actomyosin ATPase by binding to F-actin. This inhibition is attenuated by calcium-calmodulin and is potentiated by tropomyosin. Interacts with actin, myosin, two molecules of tropomyosin and with calmodulin. Also play an essential role during cellular mitosis and receptor capping. Involved in Schwann cell migration during peripheral nerve regeneration (By similarity ...
TRPM7 (transient receptor potential melastatin 7) is a Ca2+- and Mg2+-permeant ion channel in possession of its own kinase domain. As a kinase, the protein has been linked to the control of actomyosin contractility, whereas the channel has been found to regulate cell adhesion as well as cellular Mg2+ homoeostasis. In the present study we show that depletion of TRPM7 by RNA interference in fibroblasts alters cell morphology, the cytoskeleton, and the ability of cells to form lamellipodia and to execute polarized cell movements. A pulldown-purification assay revealed that knockdown of TRPM7 prevents cells from activating Rac and Cdc42 (cell division cycle 42) when stimulated to migrate into a cellular wound. Re-expression of TRPM7 reverses these phenotypic changes, as does, unexpectedly, expression of a kinase-inactive mutant of TRPM7. Surprisingly, expression of the Mg2+ transporter SLC41A2 (solute carrier family 41 member 2) is also effective in restoring the change in cell morphology, ...
Cytokinesis is the process by which a cell partitions its surface and cytoplasm to form two daughter cells. In both animal and yeast cells, this process involves the assembly and contraction of an actomyosin ring. It is noteworthy that for a long time, among the hundreds of myosins known, only the conventional myosins of class II had been implicated in cell division (Field et al., 1999). However, a recent study established the involvement of two myosins of type V in S. pombe (Win et al., 2001). The asexual multiplication of T. gondii occurs by a peculiar process named endodyogeny, which is defined as the gradual development of two daughter parasites within a fully differentiated mother; the mother is incorporated into the daughters during the process (Fig. 1). In T. gondii, actin inhibitors did not prevent replication, per se, but disrupted the inheritance of mother cell organelles, resulting in the formation of residual bodies (Shaw et al., 2000). Therefore, myosin motor(s) were anticipated to ...
25 a ON OFF b MUTIPLE CROSS BRIDGES Q) u c S(/) "0 SINGLE CROSS BRIDGE time Fig. 6. A: Diagram of crossbridge cycle. Each crossbridge repeats attachment and detachment cycle. B: Sliding movement of bead driven by single and multiple crossbridges. In summary, we have utilized in vitro motility assay techniques to study the mechanical property of cardiac myosin under various conditions for different myosin isoforms. Although these findings were anticipated based on previous experiments with muscle preparations, this is the first presentation of such direct evidence at the molecular level. 13. J. Thyroxine induced redistribution of isozyme of rabbit ventricular myosin. Circ Res 50: 117 -124, 1982. 14. , et. al. Dynamic interaction between cardiac myosin isoforms modifies velocity of actomyosin sliding in vitro. Circ Res 73:696-704, 1993. 27 15. Barany, M. ATPase activity of myosin correlated with speed of muscle shortening. J Gen Physiol 50:197-218, 1967. 16. , Poggesi, C. et. al. Shortening ...
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Actomyosin filaments[edit]. In many organisms, the force that drives furrow ingression is the assembly and contraction of ... The contractile ring is a very dynamic structure in which actomyosin filaments are continuously assembled and disassembled. The ... actomyosin filaments that often form a contractile ring. ...
Apart from actomyosin-related genes, several disease genes have recently been implicated in mitotic cell rounding. These ... "ETH ETH E-Collection: The Mechanism of Mitotic Rounding: Role of the Actomyosin Cortex - ETH". e-collection.library.ethz.ch. ... "actomyosin cortex". Nature. 469: 226-230. doi:10.1038/nature09642. PMID 21196934. Ramanathan, Subramanian P; Helenius, Jonne; ... "Changes in Ect2 localization couple actomyosin-dependent cell shape changes to mitotic progression". Developmental Cell. 23 (2 ...
Moos C, Feng IN (Oct 1980). "Effect of C-protein on actomyosin ATPase". Biochimica et Biophysica Acta. 632 (2): 141-9. doi: ...
ROCK kinases induce actomyosin-based contractility and phosphorylate TAU and MAP2 involved in regulating myosins and other ... RhoA is prevalent in regulating cell shape, polarity and locomotion via actin polymerization, actomyosin contractility, cell ... Cytokinesis is defined by actomyosin-based contraction. RhoA-dependent diaphanous-related formins (DRFs) localize to the ... mostly actin stress fibers formation and actomyosin contractility. In humans, it is encoded by the gene RHOA. It acts upon ...
Moos C, Feng IN (October 1980). "Effect of C-protein on actomyosin ATPase". Biochimica et Biophysica Acta. 632 (2): 141-9. doi: ...
subscription required) Cantelli, Gaia (2016). Transcriptional programs controlling actomyosin contractility in melanoma. ethos. ...
By the end of the 1940s Szent-Györgyi's team had postulated with evidence that contraction of actomyosin was equivalent to ... However, in one of his last contributions to muscle research, Szent-Györgyi demonstrated that actomyosin driven by ATP was the ... Cross-bridge theory states that actin and myosin form a protein complex (classically called actomyosin) by attachment of myosin ... Szent-Györgyi, A (1949). "Free-energy relations and contraction of actomyosin". The Biological Bulletin. 96 (2): 140-161. doi: ...
Korn, ED (1978). "Biochemistry of actomyosin-dependent cell motility (a review)". Proceedings of the National Academy of ...
TnI inhibits ATP-ase activity of acto-myosin; TnC is a Ca2+-binding subunit, playing the main role in Ca2+ dependent regulation ...
Inhibition of actomyosin MgATPase and regulation by phosphorylation". J. Biol. Chem. 265 (17): 10148-55. PMID 2161834. ...
1985). "ADP dissociation from actomyosin subfragment 1 is sufficiently slow to limit the unloaded shortening velocity in ... 1997). "Kinetics of nucleoside triphosphate cleavage and phosphate release steps by associated rabbit skeletal actomyosin, ... 1971). "Mechanism of adenosine triphosphate hydrolysis by actomyosin". Biochemistry. 10: 4617-4624. doi:10.1021/bi00801a004. ...
The source of cytoskeletal traction is actomyosin contractility. Increased external stiffness leads to a signal transduction ... actomyosin contractility, and cytoskeletal organization. As a result, these changes can cause a cell to rearrange its ...
Inhibition of actomyosin MgATPase and regulation by phosphorylation". J. Biol. Chem. 265 (17): 10148-55. PMID 2161834. Kabsch W ...
acto-myosin colocalization microscopy effective at 100 μM [34] C. elegans nonmuscle myosin-2 ventral enclosure effective at 100 ... Blebbistatin inhibits myosin ATPase activity and this way acto-myosin based motility. It binds halfway between the nucleotide ... This type of inhibition relaxes the acto-myosin myofilaments and leads to several biological effects. ...
Myosin cleft movement and its coupling to actomyosin dissociation. Nat Struct Biol 10(10):831-5. Photochemistry of Arenes- ...
Wolfenson, H.; Bershadsky, A.; Henis, Y. I.; Geiger, B. (2011). "Actomyosin-generated tension controls the molecular kinetics ...
Due to its importance in mitosis, the molecular components and dynamics of the mitotic actomyosin cortex is an area of active ... Matthews HK, Delabre U, Rohn JL, Guck J, Kunda P, Baum B (August 2012). "Changes in Ect2 localization couple actomyosin- ... Rounding forces are driven by reorganization of F-actin and myosin (actomyosin) into a contractile homogeneous cell cortex that ... Stewart MP, Helenius J, Toyoda Y, Ramanathan SP, Muller DJ, Hyman AA (January 2011). "Hydrostatic pressure and the actomyosin ...
The actomyosin cortex is attached to the cell membrane via membrane-anchoring proteins called ERM proteins and it plays a ... The cell cortex, also known as the actin cortex or actomyosin cortex, is a specialized layer of cytoplasmic protein on the ... The surface tension produced by the actomyosin cortex activity generates intracellular hydrostatic pressure capable of ... "Hydrostatic pressure and the actomyosin cortex drive mitotic cell rounding". Nature. 469: 226-230. doi:10.1038/nature09642. ...
These actomyosin rings invaginate to separate all nuclei for one another in the syncytial blastoderm. Anillin has a unique ... Goldbach, P., Wong, R., Beise, N., Sarpal, R., Trimble, W. S., & Brill, J. A. (2010). Stabilization of the Actomyosin Ring ... Anillins are also enriched at other actomyosin rings, most significantly, those at the leading edge of the Drosophila embryo ... Anillins have also been shown to organize the actomyosin cytoskeleton into syncytial structures observed in Drosophila embryos ...
... is a major downstream effecter of the small GTPase RhoA and is a regulator of the actomyosin cytoskeleton which promotes ... In humans, the main function of ROCK1 is actomyosin contractility. As mentioned before, this contributes to many proximal ...
... actomyosin assemblies (F-actin, myosin motors, and associated binding, nucleating, capping, stabilizing, and crosslinking ... "Hydrostatic pressure and the actomyosin cortex drive mitotic cell rounding". Nature. 469: 226-230. doi:10.1038/nature09642. ...
Like in Xenopus, actomyosin contractility plays a major role in constricting the apical side of the cell. The constricting ... In these cells, apical constriction occurs when actomyosin contractility folds the cell membrane to reduce the apical surface ... Lee, J.; Harland, R. M. (2007). "Actomyosin contractility and microtubules drive apical constriction in Xenopus bottle cells". ...
Deutsch A; Nilsson R (1954). "On the dephosphorylation and deamination of adenosine triphosphate by actomyosin gel". Acta Chem ...
"Plakophilin 2 couples actomyosin remodeling to desmosomal plaque assembly via RhoA". Molecular Biology of the Cell. 21 (16): ...
In muscle cells, actomyosin myofibrils makeup much of the cytoplasmic material. These myofibrils are made of thin filaments of ... Actomyosin networks have been implicated in generating an intrinsic chirality in individual cells. Cells grown out on chiral ... Adding ATP to a mixture of both proteins (called actomyosin) causes a decrease in viscosity. The hostilities of World War II ... particularly actomyosin. Some experiments have suggested that the pathological mechanism for this type of hearing loss relates ...
Binding affinity to chicken skeletal muscle tropomyosin within actomyosin protein complex at 125 uM after 1 hr followed by 10 ...
Mechanical measurements of single actomyosin motor force. H. Miyata, H. Yoshikawa, H. Hakozaki, N. Suzuki, Taiji Furuno, A. ... To elucidate the mechanism of force generation by actomyosin motor, a measuring system was constructed, in which an in vitro ... N2 - To elucidate the mechanism of force generation by actomyosin motor, a measuring system was constructed, in which an in ... AB - To elucidate the mechanism of force generation by actomyosin motor, a measuring system was constructed, in which an in ...
acto-myosin colocalization microscopy effective at 100 μM [34] C. elegans nonmuscle myosin-2 ventral enclosure effective at 100 ... Blebbistatin inhibits myosin ATPase activity and this way acto-myosin based motility. It binds halfway between the nucleotide ... This type of inhibition relaxes the acto-myosin myofilaments and leads to several biological effects. ...
α-Catenin controls actomyosin dynamics by stabilising and promoting the formation of actomyosin foci, and also stabilises DE- ... To this end, we have analysed the role of α-Catenin, a key molecule linking E-Cadherin-based adhesion and the actomyosin ... α-Catenin stabilises Cadherin-Catenin complexes and modulates actomyosin dynamics to allow pulsatile apical contraction ... α-Catenin stabilises Cadherin-Catenin complexes and modulates actomyosin dynamics to allow pulsatile apical contraction. ...
N2 - The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle contraction ... AB - The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle contraction ... The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle contraction, ... abstract = "The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle ...
The classic example is striated muscle, where actomyosin contractility is mediated by highly organized sarcomeres which act as ... Consistent with these results, our reconstituted actomyosin bundles show contraction at relatively high motor density, and we ...
Microtubules remodel actomyosin networks in Xenopus egg extracts via two mechanisms of F-actin transport. J. Cell Biol. 150, ...
if rigorlike str rearranges to conform seen in near rigor state on ATP intro, explains how ATP binding actomyosin rigor complex ...
The Actomyosin ring is a prominent structure during cytoplasmic division or cytokinesis (i.e., splitting from the parent cell ... In plant cells, there is no actomyosin ring. Instead a cell plate grows centrifugally outwards from the center of the plane of ... 2016). Actomyosin ring driven cytokinesis in budding yeast. Seminars in Cell & Developmental Biology 53:19-27. Alberts, B., A. ... 2016). Actomyosin Ring Formation and Tension Generation in Eukaryotic Cytokinesis. Curr Biol. 26(15):719-737. Mana-Capelli, S ...
Actomyosin definition is - a contractile complex of actin and myosin that together with ATP is active during muscular ... Comments on actomyosin. What made you want to look up actomyosin? Please tell us where you read or heard it (including the ... Post the Definition of actomyosin to Facebook Share the Definition of actomyosin on Twitter ... The first known use of actomyosin was in 1942. See more words from the same year ...
Structure of the fission yeast actomyosin ring. Matthew T. Swulius, Lam T. Nguyen, Mark S. Ladinsky, Davi R. Ortega, Samya Aich ... Structure of the fission yeast actomyosin ring. Matthew T. Swulius, Lam T. Nguyen, Mark S. Ladinsky, Davi R. Ortega, Samya Aich ... The Structure of Myosin II in S. pombe Actomyosin Ring.. Our current ECT data were not able to resolve the structure of myosin ... Structure of the fission yeast actomyosin ring during constriction. Matthew T. Swulius, Lam T. Nguyen, Mark S. Ladinsky, Davi R ...
Many attempts have thus been made to explain the molecular origin of the actomyosin motility. ... actomyosin) generates contraction force of a muscle utilizing the adenosine triphosphate (ATP) hydrolysis reaction. ... Novel intermolecular surface force reveals actomyosin driving mechanism. Tohoku University. Journal. Cytoskeleton. Keywords. * ... IMAGE: This is a novel force generation mechanism of actomyosin. An actin filament (F-actin) produces an electric field (black ...
Myosin cleft movement and its coupling to actomyosin dissociation.. Conibear PB1, Bagshaw CR, Fajer PG, Kovács M, Málnási- ... Thus ATP binding to actomyosin causes actin dissociation, whereas actin binding to the myosin accelerates ADP and phosphate ...
Hartshorne, D. J., and Siemankowski, R. F., 1981, Regulation of smooth muscle actomyosin, Ann. Rev. Physiol ., 43: 519.CrossRef ... Kohama K., Ebashi S. (1986) Inhibitory Ca2+-Regulation of the Physarum Actomyosin System. In: Dove W.F., Dee J., Hatano S., ... Ebashi, S., 1963, Third component participating in the superprecipitation of natural actomyosin, Nature, 200: 1010.PubMed ... Kato, T., and Tonomura, Y., 1975, Ca2+-sensitivity of actomyosin ATPase purified from Physarum polycephalum, J. Biochem ., 77: ...
Polar actomyosin contractility destabilizes the position of the cytokinetic furrow.. Sedzinski J1, Biro M, Oswald A, Tinevez JY ... Although studies of cytokinetic mechanics mostly focus on the equatorial constriction ring, a contractile actomyosin cortex is ...
Nonequilibrium phase diagrams for actomyosin networks S. L. Freedman, G. M. Hocky, S. Banerjee and A. R. Dinner, Soft Matter, ... we can generate three distinct structural phases of actomyosin assemblies: bundled, polarity-sorted, and contracted. We ...
We conclude that a pre-force generation ADP·Pi state is populated in the actomyosin ATPase cycle, which may be critical for the ... 2004) Coupling between phosphate release and force generation in muscle actomyosin. Philos Trans R Soc Lond B Biol Sci 359:1913 ... Characterization of the pre-force-generation state in the actomyosin cross-bridge cycle. Mingxuan Sun, Michael B. Rose, Shobana ... 2005) Magnesium, ADP, and actin binding linkage of myosin V: Evidence for multiple myosin V-ADP and actomyosin V-ADP states. ...
... Maegen A. Ackermann and Aikaterini ... Maegen A. Ackermann and Aikaterini Kontrogianni-Konstantopoulos, "Myosin Binding Protein-C: A Regulator of Actomyosin ...
Cannabinoid-induced actomyosin contractility shapes neuronal morphology and growth.. [Alexandre B Roland, Ana Ricobaraza, ... Our results suggest that CB1R can rapidly transform the neuronal cytoskeleton through actomyosin contractility, resulting in ... dependent contraction of the actomyosin cytoskeleton, through a Rho-GTPase and Rho-associated kinase (ROCK). This induces rapid ...
Myosin IIA-related Actomyosin Contractility Mediates Oxidative Stress-induced Neuronal Apoptosis.. [Yan Wang, Yingqiong Xu, ...
... Dev Biol. 2007 Nov 1;311(1):40-52. ... Our results indicate that actomyosin contractility is required for bottle cell morphogenesis and further suggest a novel and ... showing that actomyosin contractility is required for apical constriction. Microtubules were localized in apicobasally directed ...
It is often assumed that this simple sliding is sufficient to account for all actomyosin-based motion. While this is correct in ... our highly organized striated muscle, we question the application of this dogma to less ordered actomyosin systems, thus ... It is often assumed that this simple sliding is sufficient to account for all actomyosin-based motion. While this is correct in ... our highly organized striated muscle, we question the application of this dogma to less ordered actomyosin systems, thus ...
Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution.. Ecken, J.V., Heissler, S.M., Pathan- ... Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution. *DOI: 10.2210/pdb5JLH/pdb ... Here, using electron cryomicroscopy, we present the structure of a human rigor actomyosin complex at an average resolution of ... The structure reveals details of the actomyosin interface, which is mainly stabilized by hydrophobic interactions. The ...
Consequently, possible roles of actomyosin contraction in organizing and maintaining structural properties of dendritic spines ... recent findings involving myosin localization and function in these compartments and to discuss possible roles for actomyosin ... Actomyosin Contractility in the Generation and Plasticity of Axons and Dendritic Spines by Marina Mikhaylova 1,2,*. , Jakob ... "Actomyosin Contractility in the Generation and Plasticity of Axons and Dendritic Spines." Cells 9, no. 9: 2006. ...
Sculpting Actomyosin. The sculpting of embryos during development involves coordinated movement of cells in large groups. How ... PCP and Septins Compartmentalize Cortical Actomyosin to Direct Collective Cell Movement Message Subject. (Your Name) has ... Despite our understanding of actomyosin function in individual migrating cells, we know little about the mechanisms by which ... By directing septin-mediated compartmentalization of cortical actomyosin, PCP proteins coordinate the specific shortening of ...
  • To provide a clue to resolve the controversy between the lever-arm mechanism and the Brownian ratchet-like mechanism, we here report an in silico single molecule experiment of an actomyosin motor.When we placed myosin on an actin filament and allowed myosin to move along the filament, we found that myosin exhibits a unidirectional Brownian motion along the filament. (elsevier.com)
  • To elucidate the mechanism of force generation by actomyosin motor, a measuring system was constructed, in which an in vitro motility assay was combined with an optical trapping technique. (elsevier.com)
  • While contractile behaviors of actomyosin machinery have been studied extensively in several in vitro experiments and computational studies, the pulsatile contraction of actomyosin networks observed in vivo has not been recapitulated well. (aps.org)
  • Here, we employed an agent-based computational model based on Brownian dynamics to identify critical factors facilitating the pulsatile contraction of actomyosin networks. (aps.org)
  • We found that the strong pulsatile contraction of actomyosin networks only occurs when there is subtle balance between force generation from motors, global force relaxation via actin turnover, and local force relaxation via angle-dependent actin severing. (aps.org)
  • A supracellular actomyosin cable around the wound coordinates cellular movements and promotes wound closure. (utoronto.ca)
  • In the study, the water structure in close proximity of an actin filament (F-actin) is modified upon binding with a myosin head hydrolyzing ATP to F-actin, that leads to a change in the affinity to the myosin head and thus to the generation of the driving force of actomyosin. (eurekalert.org)
  • Many attempts have thus been made to explain the molecular origin of the actomyosin motility. (eurekalert.org)
  • In this study, we compared the phenotypes of different mutants for core components of the actomyosin system in Toxoplasma gondii to decipher their exact role during gliding motility and invasion. (beds.ac.uk)
  • The current model for gliding motility is centred on the actomyosin system of the parasite in force generation during this process. (beds.ac.uk)
  • Maegen A. Ackermann and Aikaterini Kontrogianni-Konstantopoulos, "Myosin Binding Protein-C: A Regulator of Actomyosin Interaction in Striated Muscle," Journal of Biomedicine and Biotechnology , vol. 2011, Article ID 636403, 9 pages, 2011. (hindawi.com)
  • Glover, David M. / Interaction between Anillin and RacGAP50C connects the actomyosin contractile ring with spindle microtubules at the cell division site . (elsevier.com)
  • In C. elegans, actomyosin networks were initially dynamic, contracting and generating cortical tension without substantial shrinking of apical surfaces. (unc.edu)
  • Using photobleaching and pharmacological perturbations in vivo, we show that actomyosin contractility and actin polymerization together push on the underlying vesicle membrane to overcome the energy barrier and complete exocytosis 7 . (elsevier.com)
  • Functional perturbations of drebrin demonstrate that proximal leading process microtubule-actomyosin coupling steers the direction of centrosome and somal migration, as well as the switch from tangential to radial migration. (kcl.ac.uk)
  • While it is hypothesized that microtubule-actomyosin crosstalk is required for a neuron's 'two-stroke' nucleokinesis cycle, the molecular mechanisms controlling such crosstalk are not defined. (kcl.ac.uk)
  • While compensatory mechanisms and unusual polymerisation kinetics of parasite actin have been evoked to explain these findings, the actomyosin system could also play a role distinct from force production during parasite movement. (beds.ac.uk)
  • My lab has recently focused on elucidating mechanisms of actomyosin contractility using the computational models. (purdue.edu)
  • Dynamic mechanisms of cell rigidity sensing: insights from a computational model of actomyosin networks. (purdue.edu)
  • The arrested posterior hemisphere will resume and complete inversion even in the presence of an actomyosin inhibitor if the anterior hemisphere is removed microsurgically. (biologists.org)