• Through use of TIRF microscopy, researchers have visually observed the nucleation of branching microtubules in Drosophila cells during the formation of the mitotic spindle. (wikipedia.org)
  • The mitotic spindle is a dynamic microtubule-based apparatus that ensures the segregation of chromosomes during cell division. (nature.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)
  • More over, TPX2 is only necessary for a part of Aurora A dependent processes: TPX2 inactivation by RNAi causes spindle problems and reduction of Aurora A from the mitotic spindle, but centrosome maturation is normal, and the centrosome pool of the kinase is unchanged. (others-signal.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)
  • The centrosome is the most common MTOC for multipotent cells in animals, with differentiated tissues utilising a wide variety of non-centrosomal MTOCs. (wikipedia.org)
  • Some cells however, such as those of higher plants and oocytes, lack distinct MTOCs and microtubules are nucleated via a non-centrosomal pathway. (wikipedia.org)
  • These non-centrosomal microtubule arrays can take on various geometries-such as those leading to the long, slender shape of myotubes, the fine protrusions of an axon, or the strongly polarized domains of an epithelial cell. (wikipedia.org)
  • The early cells of the pre-implantation mouse embryo utilise a unique non-centrosomal MTOC, in the form of an interphase microtubule bridge joining sister cells. (wikipedia.org)
  • These branching microtubules maintain the same polarity as their mother microtubules, and their assembly involves the binding of non-centrosomal γ-TuRCs to the sides of existing microtubules through the augmin complex. (wikipedia.org)
  • γ-Tubulin is a centrosomal component involved in microtubule nucleation. (silverchair.com)
  • Together with dynactin, dynein regulates centrosomal orientation to establish and maintain cell polarity, controls focal adhesion turnover and anchors microtubules at the leading edge. (biologists.com)
  • In particular we investigate the production and balance of mechanical forces in the networks of actin filaments and microtubules. (hipi-lab-saint-louis.fr)
  • Actin filaments and microtubules form such complex intricate networks in cells that it is difficult to identify the principles of their self-organization. (hipi-lab-saint-louis.fr)
  • Within the myoblasts, long filaments called microtubules are arranged in an overlapping linear pattern. (elifesciences.org)
  • used microscopy to observe the formation of the microtubule filaments in living myoblasts. (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)
  • The spatial organization of these filaments and their dynamics of assembly direct cell shape and cell motion. (cerclefser.org)
  • Similar to the formation of actin filaments from the self-assembly of actin monomers, tubulin forms asymmetric dimers that can self-assemble into microtubules. (cerclefser.org)
  • Compared with actin filaments, microtubules are much more rigid, and almost straight in the dimensions of a single cell. (cerclefser.org)
  • Microtubules can sustain much higher compression forces than actin filament but are not as numerous as actin filaments. (cerclefser.org)
  • Together, these observations argue that arc assembly occurs through a formin-dependent mechanism (i.e. independent of Arp2/3-mediated nucleation), and that myosin II contractility is required for reorienting the perpendicular filaments emanating from the dSMAC into the concentric arcs in the pSMAC. (grantome.com)
  • A kinase anchoring protein 350 (AKAP350) is a centrosome/Golgi-associated protein, which, in T cells, participates in LFA-1 activation by mechanisms that have not been elucidated. (bvsalud.org)
  • They develop in a juxtanuclear position, adjacent to the centrosome, the microtubule organizing centre of the cell, and share some protein components. (biorxiv.org)
  • Despite the long-standing observation that aggresomes/Lewy bodies and the centrosome sit side-by-side in the cell, no studies have been done to see whether these protein accumulations impede the organelle function. (biorxiv.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)
  • 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)
  • Here we sought to determine whether the microtubule-severing protein known as katanin mediates microtubule release from the neuronal centrosome. (silverchair.com)
  • Microtubule nucleation occurs spontaneously in vitro, with solutions of purified tubulin giving rise to full-length polymers. (wikipedia.org)
  • The primary pathway by which microtubule nucleation is assisted requires the action of a third type of tubulin, γ-tubulin, which is distinct from the α and β subunits that compose the microtubules themselves. (wikipedia.org)
  • This complex, with its 13-fold symmetry, acts as a scaffold or template for α/β tubulin dimers during the nucleation process-speeding up the assembly of the ring of 13 protofilaments that make up the growing microtubule. (wikipedia.org)
  • Five proteins in Drosophila (DGT2 through DGT6) have been identified that are necessary and responsible for facilitating the localization of γ-tubulin to existing MTs and are not associated with its localization at the centrosome. (wikipedia.org)
  • Fluorescence recovery after photobleaching (FRAP) studies reveal that the centrosome possesses two populations of γ-tubulin: one that turns over rapidly and another that is more tightly bound. (silverchair.com)
  • These data are the first to characterize the dynamics of centrosome-associated γ-tubulin in vertebrate cells in vivo and to demonstrate the microtubule-independent nature of these dynamics. (silverchair.com)
  • Recent studies using improved Ub detection methods have confirmed that tubulin is ubiquitinated 9-11 , a modification which regulates α/β-tubulin turnover as well as MT dynamics and function. (cytoskeleton.com)
  • The pivotal structure of the primary cilia is a microtubule that is generated via tubulin polymerization reaction that occurs in the basal body. (biomedcentral.com)
  • Current models propose that displacement of the spindle poles and/or the activity of kinetochore microtubules generate mechanical forces that segregate sister chromatids. (ens-lyon.fr)
  • We find that when aggresomes are present, neuronal cells are unable to organise their microtubule network. (biorxiv.org)
  • Since dopaminergic neurons are polarised, ensuring correct localisation of organelles and the effective intracellular transport of neurotransmitter vesicles, loss of centrosome activity could contribute to loss of dopaminergic function and neuronal cell death in Parkinson's disease. (biorxiv.org)
  • Several lines of evidence suggest that microtubules are nucleated at the neuronal centrosome, and then released for transport into axons and dendrites. (silverchair.com)
  • These results indicate that microtubule-severing by katanin is essential for releasing microtubules from the neuronal centrosome, and also for regulating the length of the microtubules after their release. (silverchair.com)
  • Purified oMAP4 aligns dynamic microtubules into antiparallel bundles that withstand motor forces in vitro. (elifesciences.org)
  • The role of microtubule pivoting in formation of complex structures such as microtubule bundles and mitotic spindles. (irb.hr)
  • Among its other functions, this radial array is used by microtubule-based motor proteins to transport various cargoes, such as vesicles, to the plasma membrane. (wikipedia.org)
  • Immunomicroscopic analyses on cultured sympathetic neurons show that katanin is present at the centrosome, but is also widely distributed throughout the neuron. (silverchair.com)
  • Microinjection of an antibody that inactivates katanin results in a dramatic accumulation of microtubules at the centrosome, indicating that katanin is indeed required for microtubule release from the centrosome. (silverchair.com)
  • It may be that katanin severs microtubules throughout the cell body to keep them sufficiently short to be efficiently transported into developing processes. (silverchair.com)
  • Consistent with this idea, there were significantly fewer free ends of microtubules in the cell bodies of neurons that had been injected with the katanin antibody compared with controls. (silverchair.com)
  • The γ-TuRC is typically found as the core functional unit in a microtubule organizing center (MTOC), such as the centrosome in some animal cells or the spindle pole bodies in fungi and algae. (wikipedia.org)
  • 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)
  • 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 vitro reconstituted systems will be used to control the actin nucleation patterns, the closed volume of the reaction chamber and the physical interaction of the networks. (hipi-lab-saint-louis.fr)
  • Dynein is the sole processive minus-end-directed microtubule motor found in animals. (biologists.com)
  • Most notably, oMAP4 is required for paraxial microtubule organisation in muscle cells and prevents dynein- and kinesin-driven microtubule-microtubule sliding. (elifesciences.org)
  • 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)
  • 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)
  • Despite their fundamental importance in the regulation of cell physiology, the basic mechanisms that control the coordinated dynamics of co-existing actin networks are poorly understood. (hipi-lab-saint-louis.fr)
  • In toto , our results show that the connection between centrosomes and chromosomes is mediated by an anchoring into the entire spindle network and that any direct connections through KMTs are few and likely very transient. (nature.com)
  • If the role of KMTs is to mediate forces between chromosomes and spindle poles, they need to somehow connect to the centrosomes. (nature.com)
  • Our results strongly suggest that an outward forcegenerated by the spindle midzone, independently of centrosomes, is sufficient tosegregate chromosomes in mitotic cells. (ens-lyon.fr)
  • In cell biology, microtubule nucleation is the event that initiates de novo formation of microtubules (MTs). (wikipedia.org)
  • Microtubules grow from this domain in parallel lines, giving the cell its rectangular shape. (wikipedia.org)
  • Here we combine the first large-scale serial electron tomography of whole mitotic spindles in early C. elegans embryos with live-cell imaging to reconstruct all microtubules in 3D and identify their plus- and minus-ends. (nature.com)
  • 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)
  • We have proposed a model whereby these features of the axonal and dendritic microtubule arrays are established within the cell body of the neuron. (silverchair.com)
  • Cytoskeletal dynamics and spindle assembly during cell division. (irb.hr)
  • The spindle microtubule (MT) exhibits highly regulated dynamic instability, with frequent polymerization and depolymerization occurring at both the plus and minus ends. (biomedcentral.com)
  • 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)
  • These tools allow us to analyze and quantify actin and microtubule networks in cells of controled and regular shapes. (hipi-lab-saint-louis.fr)
  • 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)
  • In this fashion, dynamic arrays of microtubules can be generated without the aid of the γ-TuRC. (wikipedia.org)
  • Second, we will use our unique capacity to perform dynamic micropatterning, to add or remove actin nucleation sites in real time, in order to investigate the ability of dynamic networks to adapt to changes and the role of coupled network dynamics in this emergent property. (hipi-lab-saint-louis.fr)
  • The microtubules within these processes have a consistent 13-protofilament lattice and are tightly regulated with regard to their polarity orientation. (silverchair.com)
  • Branching MT nucleation has been observed in numerous organisms both in the plant and animal kingdoms. (wikipedia.org)
  • In both cases we try to relate network dynamics to its physical properties and the eventual production of mechanical forces. (cerclefser.org)
  • The implications of those findings have influenced almost all further research of intracellular processes, including RAS signaling, immune synapses, DNA repair, transcriptional activation, and the functions of nuclear pores, the nucleolus and centrosomes. (hymanlab.org)
  • This cap provides both stability and protection to the microtubule (-) end from enzymes that could lead to its depolymerization, while also inhibiting (-) end growth. (wikipedia.org)
  • TPX2/ Aurora A binding is stimulated by the little GTPase Ran, which in turn is activated by RCC1, an exchange factor that is found on condensed chromatin and is involved with microtubule nucleation and spindle formation. (others-signal.com)