• The kinetochore assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis. (wikipedia.org)
  • It has also been reported that the kinetochore organization differs between mitosis and meiosis and the integrity of meiotic kinetochore is essential for meiosis specific events such as pairing of homologous chromosomes, sister kinetochore monoorientation, protection of centromeric cohesin and spindle-pole body cohesion and duplication. (wikipedia.org)
  • Remarkably, despite the high turnover of microtubules throughout mitosis 2 , the spindle maintains its bipolar structure with the chromosomes at its center and two poles that are separated by the plane of cell division. (nature.com)
  • This stereotypical arrangement is widely believed to mediate the forces between the metaphase plate and the poles that separate sister chromatids during mitosis. (nature.com)
  • Indeed, that such forces exist in C. elegans is evidenced by the maintenance of half-spindle lengths throughout mitosis 5 and in many perturbations experiments. (nature.com)
  • During mitosis, chromosomes are connected to a microtubule-based spindle. (ens-lyon.fr)
  • Conversely, we identify a novel role for two microtubule-growth and nucleation agents, Ran and CLASP, in the establishment of the centrosome-independent force during anaphase.Their involvement raises the interesting possibility that microtubule polymerization of midzone microtubules is continuously required to sustain chromosome segregation during mitosis. (ens-lyon.fr)
  • 2009). Chromator is required for proper microtubule spindle formation and mitosis in Drosophila . (up.pt)
  • At the onset of mitosis, centrosomes become the core structures of spindle poles and direct the formation of mitotic spindles. (biomedcentral.com)
  • In early mitosis, the cohesion between the two pairs of centrioles is broken and each of them participates in the formation of the mitotic spindle pole. (biomedcentral.com)
  • During mitosis the two centrosomes are present and form the mitotic spindle poles. (biomedcentral.com)
  • Our data reveal a spindle-directed signalling pathway that regulates SCAR activity, migration and adhesion at mitosis. (biologists.com)
  • Moreover, the implication that the active form of Ran is concentrated in the vicinity of chromosomes suggests that these findings may resolve the long-standing question of how chromosomes can influence spindle assembly in the absence of microtubule-nucleating organelles (i.e., as in plant mitosis or mammalian meiosis). (silverchair.com)
  • These mitotic kinesins are spatially and temporally regulated to stringently control their localized activity towards both ends of MTs at each stage of mitosis, thereby ensuring mitotic fidelity [ 3 ]. (biomedcentral.com)
  • Indeed, by quantitatively analysing several models of microtubule growth, we conclude that minus-ends of KMTs have selectively detached and depolymerized from the centrosome. (nature.com)
  • Acts as a centrosome maturation factor, probably by maintaining the integrity of the pericentriolar material and proper microtubule nucleation at mitotic spindle poles. (univ-amu.fr)
  • the SSX2IP:WRAP73 complex is proposed to act as regulator of spindle anchoring at the mitotic centrosome (PubMed:23816619, PubMed:26545777). (univ-amu.fr)
  • In contrast to well-studied fungal and animal cells, plant cells assemble bipolar spindles that exhibit a great deal of plasticity in the absence of structurally defined microtubule-organizing centers like the centrosome. (nsf.gov)
  • Although many key factors contributing to MT nucleation and organization are well conserved in different kingdoms, the centrosome, representing the most prominent microtubule organizing centers ( MTOC s), disappeared during plant evolution as angiosperms lack the structure. (nsf.gov)
  • Predicted to be active in centrosome and equatorial microtubule organizing center. (nih.gov)
  • Recent breakthroughs have uncovered more and more DNA replication licensing machinery proteins (ORC, Cdc6, Cdt1, geminin, etc.) functioning in other cell cycle events, including centrosome replication, mitotic events, transcription and so on. (intechopen.com)
  • Here, centrioles, contained in the centrosome , are responsible for the production of microtubules that form the central fibers. (microscopemaster.com)
  • In higher plants, microtubule organizing centers (centrosome) is absent. (microscopemaster.com)
  • They develop in a juxtanuclear position, adjacent to the centrosome, the microtubule organizing centre of the cell, and share some protein components. (biorxiv.org)
  • We investigated whether the formation of aggresomes affected key centrosome functions: its ability to organize the microtubule network and to promote cilia formation. (biorxiv.org)
  • The juxtanuclear location of the aggresome is shared by the centrosome, the microtubule organising centre of the cell. (biorxiv.org)
  • Following the transition from metaphase to anaphase, the sister chromatids separate from each other, and the individual kinetochores on each chromatid drive their movement to the spindle poles that will define the two new daughter cells. (wikipedia.org)
  • Of note, compared to fungal and animal systems, relatively little is known about how plant cells remodel the spindle microtubule array during anaphase. (nsf.gov)
  • The anaphase stage, following metaphase, is characterized by the development of spindle fibers. (microscopemaster.com)
  • PIP4KIIγ accumulates at the spindle pole before anaphase, and is required for the assembly of functional bipolar spindles. (biomedcentral.com)
  • Our current results imply that PIP4KIIγ may restrain MT depolymerization at the spindle pole through attenuating PLK1-mediated activation of MCAK before anaphase onset. (biomedcentral.com)
  • Although the positioning signal is likely to be transmitted via the anaphase microtubule array to the cell cortex, exactly how the microtubule array determines the site of contractile ring formation remains unresolved. (biologists.com)
  • These data support a model in which Tum/RacGAP, via its interaction with Pbl, provides a critical link between the anaphase microtubule spindle and cytokinetic furrow formation in Drosophila cells. (biologists.com)
  • Other proteins, such as Mad2, monitor the microtubule attachment as well as the tension between sister kinetochores and activate the spindle checkpoint to arrest the cell cycle when either of these is absent. (wikipedia.org)
  • Plants also produce proteins distantly related to their fungal and animal counterparts to regulate critical events such as the spindle assembly checkpoint. (nsf.gov)
  • BUB1 mitotic checkpoint serine/threo. (gsea-msigdb.org)
  • We propose a model where Cdk1-dependent phosphorylation of γ-tubulin allows each microtubule to behave independently of its neighbors during spindle assembly. (monbug.ca)
  • Mitotic phosphorylation of Exo84 disrupts the assembly of the exocyst complex, thereby inhibiting exocytosis of select secreted cargoes and cell surface expansion. (silverchair.com)
  • The microtubule cytoskeleton is critical for muscle cell differentiation and undergoes reorganisation into an array of paraxial microtubules, which serves as template for contractile sarcomere formation. (elifesciences.org)
  • Other proteins in the kinetochore adhere it to the microtubules (MTs) of the mitotic spindle. (wikipedia.org)
  • While plants employ some evolutionarily conserved proteins to regulate spindle morphogenesis and remodeling, many essential spindle assembly factors found in vertebrates are either missing or not required for producing the plant bipolar microtubule array. (nsf.gov)
  • Uncovering mitotic functions of novel proteins for spindle assembly in plants will illuminate both common and divergent mechanisms employed by different eukaryotic organisms to segregate genetic materials. (nsf.gov)
  • It is intriguing what proteins are associated with plant‐specific MTOC s and how plant cells activate or inactivate MT nucleation activities in spatiotemporally regulated manners. (nsf.gov)
  • The PCM is an ordered lattice that anchors a large number of microtubule (MT)-associated proteins, many of which bear putative coiled-coil domains, a tertiary structure known to facilitate protein-protein interactions [ 4 ]. (biomedcentral.com)
  • A family of microtubule-associated proteins (or 'MAPs' for short) bind to microtubules and assist in organising the filaments, but it is not clear how they work. (elifesciences.org)
  • The experiments also found that oMAP4 can create links between different microtubules and act as a brake to prevent the filaments being moved excessively by motor proteins. (elifesciences.org)
  • Instead, Ran and its associated proteins shift their focus from nuclear transport to the regulation of microtubule dynamics. (silverchair.com)
  • We classify them as kinetochore (KMTs), spindle (SMTs) or astral microtubules (AMTs) according to their positions, and quantify distinct properties of each class. (nature.com)
  • In this paper, we set out to identify the cytoskeletal ultrastructure in C. elegans mitotic spindles that underlies this function, and how this ultrastructure is generated, using a combination of large-scale electron tomography, light microscopy and mathematical modelling. (nature.com)
  • Cytoskeletal microtubules ( MT s) have a multitude of functions including intracellular distribution of molecules and organelles, cell morphogenesis, as well as segregation of the genetic material and separation of the cytoplasm during cell division among eukaryotic organisms. (nsf.gov)
  • Cytoskeletal dynamics and spindle assembly during cell division. (irb.hr)
  • While our light microscopy and mutant studies show that microtubules are nucleated from the centrosomes, we find only a few KMTs directly connected to the centrosomes. (nature.com)
  • In the meiosis of many species, the process of chromosome segregation requires that bipolar spindles be formed without the aid of dedicated microtubule organizing centers, such as centrosomes. (nsf.gov)
  • Centrosomes are the major microtubule organizing structures in vertebrate cells. (biomedcentral.com)
  • In animal cells, centrosomes represent the major microtubule-organizing structures (MTOC). (biomedcentral.com)
  • It is predicted that MCPH gene mutations may lead to the disease phenotype due to a disturbed mitotic spindle orientation, premature chromosomal condensation, signalling response as a result of damaged DNA, microtubule dynamics, transcriptional control or a few other hidden centrosomal mechanisms that can regulate the number of neurons produced by neuronal precursor cells. (biomedcentral.com)
  • Gamma-tubulin complexes and their interaction with microtubule-organizing centers. (nih.gov)
  • 2010). CLASP1, astrin and Kif2b form a molecular switch that regulates kinetochore-microtubule dynamics to promote mitotic progression and fidelity . (up.pt)
  • The instability of MT dynamics depends heavily on mitotic kinesins, a class of molecular motors, which use the energy from ATP hydrolysis to translocate along the MT or control MT dynamics by facilitating MT polymerization and depolymerization at both ends. (biomedcentral.com)
  • We show that the actin nucleation factor SCAR/WAVE is strongly activated during Dictyostelium cytokinesis. (biologists.com)
  • The GAP activity of Tum is required for cytokinesis: in its absence cytokinesis fails early even though Tum is present on microtubules at the cell equator where the furrow should form. (biologists.com)
  • A kinetochore (/kɪˈnɛtəkɔːr/, /-ˈniːtəkɔːr/) is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. (wikipedia.org)
  • The mitotic spindle performs this function in eukaryotic cells. (monbug.ca)
  • Recent findings by several groups have shown that the GTP-bound form of Ran is necessary for the nucleation and organization of microtubule structures during M phase. (silverchair.com)
  • In this study, we explored how PIP4KIIγ regulates the assembly of mitotic spindles. (biomedcentral.com)
  • It has been demonstrated that members of the PIP5KI and PIP4KII families are specifically phosphorylated at the mitotic stage [ 9 ], suggesting that they may contribute to the control of mitotic progression. (biomedcentral.com)
  • Loss of SCAR in both Dictyostelium and Drosophila leads to a similar mitotic phenotype, with severe mitotic blebbing, indicating conserved functionality. (biologists.com)
  • In plants and yeast , position of the cleavage furrow is said to be independent of the mitotic spindle. (microscopemaster.com)
  • In animal cells, new reports are showing that spindle fibers are responsible for the position of the cleavage furrow. (microscopemaster.com)
  • At the cell equator, these factors stimulate the recruitment of formins which in turn results in the nucleation of actin filaments as well as myosin localization. (microscopemaster.com)
  • The role of microtubule pivoting in formation of complex structures such as microtubule bundles and mitotic spindles. (irb.hr)
  • Purified oMAP4 aligns dynamic microtubules into antiparallel bundles that withstand motor forces in vitro. (elifesciences.org)
  • Plant spindle assembly initiates with microtubule nucleation on the nuclear envelope followed by bipolarization into the prophase spindle. (nsf.gov)
  • Here, we describe detailed analyses of acentrosomal spindle assembly and disassembly in time-lapse images, from live meiotic cells of Zea mays. (nsf.gov)
  • Using a diverse set of quantitative tools, based in single cell and population measurements, we show that g-tubulin plays an unexpected role in orchestrating the formation of anti-parallel microtubules during the assembly of mitotic spindle. (monbug.ca)
  • We propose a model in which the cooperation of dynein-mediated microtubule transport and oMAP4-mediated zippering of microtubules drives formation of a paraxial microtubule array that provides critical support for the polarisation and elongation of myotubes. (elifesciences.org)
  • Most notably, oMAP4 is required for paraxial microtubule organisation in muscle cells and prevents dynein- and kinesin-driven microtubule-microtubule sliding. (elifesciences.org)
  • Using mutant and RNAi analysis, we show that the microtubule-bundling protein SPD-1/MAP-65 and BMK-1/kinesin-5 act as a brake opposing the force generated by the spindle midzone. (ens-lyon.fr)
  • We also find that the microtubule end-binding protein EB1 is required to restrict SCAR localisation and direct migration. (biologists.com)
  • In this study, we identify a previously uncharacterised isoform of microtubule-associated protein MAP4, oMAP4, as a microtubule organising factor that is crucial for myogenesis. (elifesciences.org)
  • The microtubules in cells that make smaller amounts of this protein were more disorganised, and these cells were unable to fuse with each other to form muscle cells. (elifesciences.org)
  • A previous screen of a human kinase and phosphatase shRNA library to select genes that mediate arsenite induction of spindle abnormalities resulted in the identification of phosphatidylinositol-5-phosphate 4-kinase type-2 gamma (PIP4KIIγ), a phosphatidylinositol 4,5-bisphosphate (PIP2)-synthesizing enzyme. (biomedcentral.com)
  • used microscopy to observe the formation of the microtubule filaments in living myoblasts. (elifesciences.org)
  • Therefore, the next challenge is to understand how other processes-such as the selective stabilisation of some microtubules and the movement of cell materials along the microtubules-cooperate to control muscle fibre formation. (elifesciences.org)
  • In addition, coordination of MT polymerization/depolymerization at both ends to maintain the size and shape of mitotic spindles is also critical for the proper formation and function of the mitotic spindle. (biomedcentral.com)
  • MT ‐dependent MT nucleation is particularly noticeable in plant cells because it accounts for the primary source of MT generation for assembling spindle, phragmoplast, and cortical arrays when the γ‐tubulin ring complex is anchored and activated by the augmin complex. (nsf.gov)
  • We find that when aggresomes are present, neuronal cells are unable to organise their microtubule network. (biorxiv.org)
  • New microtubules are not nucleated and extended, and the cells fail to respond to polarity cues. (biorxiv.org)
  • In contrast to the classic satellite marker PCM-1 (blue), SSX2IP (red) localizes to the spindle poles in mitotic cells. (silverchair.com)
  • 2012). CLASPs prevent irreversible multipolarity by ensuring spindle-pole resistance to traction forces during chromosome alignment . (up.pt)
  • On the other hand, microtubules are metastable polymers made of α- and β-tubulin, alternating between growing and shrinking phases, a phenomenon known as dynamic instability. (wikipedia.org)
  • Consequently, depletion of PLK1 has been shown to counteract the PIP4KIIγ depletion-induced instability of spindle pole-associated MT and cell resistance to arsenite. (biomedcentral.com)
  • The spindle microtubule (MT) exhibits highly regulated dynamic instability, with frequent polymerization and depolymerization occurring at both the plus and minus ends. (biomedcentral.com)
  • Depletion of PIP4KIIγ enhanced the spindle pole accumulation of mitotic centromere-associated kinesin (MCAK), a microtubule (MT)-depolymerizing kinesin, and resulted in a less stable spindle pole-associated MT. Depletion of MCAK can ameliorate PIP4KIIγ depletion-induced spindle abnormalities. (biomedcentral.com)
  • MCPH is a neurogenic mitotic disorder, though affected patients demonstrate normal neuronal migration, neuronal apoptosis and neural function. (biomedcentral.com)
  • In budding yeast, single continuous KMTs span the full pole-to-chromosome distance 6 . (nature.com)
  • In the case of budding yeast, the system is very minimal- one microtubule attaches to each of the 16 duplicated chromosome (32), and 3-4 pairs of anti-parallel microtubules. (monbug.ca)
  • Predicted to enable gamma-tubulin binding activity and microtubule binding activity. (nih.gov)
  • Microtubule nucleation by γ-tubulin complexes. (nih.gov)