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)
The augmin complex plays a role in microtubule attachment to the kinetochore and central spindle formation. (nih.gov)
The microtubule-associated protein EML3 regulates mitotic spindle assembly by recruiting the Augmin complex to spindle microtubules. (nih.gov)
Abstract Microtubules that assemble the mitotic spindle are generated by centrosomal nucleation, chromatin-mediated nucleation, and nucleation from the surface of other microtubules mediated by the augmin complex. (climat2050.org)
Mitotic spindle3
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)
FAM29A promotes microtubule amplification via recruitment of the NEDD1-gamma-tubulin complex to the mitotic spindle. (nih.gov)
Centrosomal microtubules were proposed to be at the core of these fate decisions, by controlling the distribution of cell fate determinants through correct positioning of the mitotic spindle (Homem et al. (climat2050.org)
This method of microtubule-dependent microtubule nucleation leads to rapid amplification in microtubule density. (wikipedia.org)
This protein may have a role in efficient chromosome congression and segregation by promoting microtubule-dependent microtubule amplification. (nih.gov)
Augmin accumulation on long-lived microtubules drives amplification and kinetochore-directed growth. (nih.gov)
Katanin7
In the cortical array of plants, as well as in the axons of neurons, it is theorised that microtubules nucleate from existing microtubules via the action of severing enzymes such as katanin. (wikipedia.org)
Here we sought to determine whether the microtubule-severing protein known as katanin mediates microtubule release from the neuronal centrosome. (silverchair.com)
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)
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)
Accumulation1
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)
Spindle pole1
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)
Cytoskeleton2
These filaments of the cytoskeleton typically form through polymerization of α- and β-tubulin dimers, the basic building blocks of the microtubule, which initially interact to nucleate a seed from which the filament elongates. (wikipedia.org)
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)
Depolymerization2
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)
The spindle microtubule (MT) exhibits highly regulated dynamic instability, with frequent polymerization and depolymerization occurring at both the plus and minus ends. (biomedcentral.com)
Associated proteins2
Instead, Ran and its associated proteins shift their focus from nuclear transport to the regulation of microtubule dynamics. (silverchair.com)
Impairment of centrosomal nucleation in apical progenitors of the developing mouse brain induces p53-dependent apoptosis and causes non-lethal microcephaly. (climat2050.org)
Thus, in contrast to centrosomes, augmin is crucial for apical progenitor mitosis, and, even in the absence of p53, for progression of brain development. (climat2050.org)
Filaments3
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)
Vitro2
Microtubule nucleation occurs spontaneously in vitro, with solutions of purified tubulin giving rise to full-length polymers. (wikipedia.org)
Purified oMAP4 aligns dynamic microtubules into antiparallel bundles that withstand motor forces in vitro. (elifesciences.org)
Neurons1
Other cells, such as neurons, skeletal muscle cells, and epithelial cells, which do have MTOCs, possess arrays of microtubules not associated with a centrosome. (wikipedia.org)
Protein2
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)
Occurs1
2016). However, since early mouse development occurs in the absence of centrosomes (Gueth-Hallonet et al. (climat2050.org)
Arrays6
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)
Akin to the action of cofilin in generating actin filament arrays, the severing of microtubules by MAPs creates new plus (+) ends from which microtubules can grow. (wikipedia.org)
In this fashion, dynamic arrays of microtubules can be generated without the aid of the γ-TuRC. (wikipedia.org)
Studies using Xenopus egg extracts have identified a novel form of microtubule nucleation that generates fan-like branching arrays, in which new microtubules grow at an angle off of older microtubules. (wikipedia.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)
Absence1
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)
Prevents1
Most notably, oMAP4 is required for paraxial microtubule organisation in muscle cells and prevents dynein- and kinesin-driven microtubule-microtubule sliding. (elifesciences.org)
Functional1
Gene mutations that cause functional or numerical centrosome aberrations are associated with main microcephaly, a developmental disorder that results in the?reduced thickness of the cerebral cortex. (climat2050.org)
Processes2
The microtubules within these processes have a consistent 13-protofilament lattice and are tightly regulated with regard to their polarity orientation. (silverchair.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)
Axons1
Several lines of evidence suggest that microtubules are nucleated at the neuronal centrosome, and then released for transport into axons and dendrites. (silverchair.com)
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)
egg extract and cultured cell models have generated a wealth of information regarding the types of AZD-4320 spindle defects that occur when specific nucleation pathways are compromised, how these defects impinge on cell fate and development remains poorly defined. (climat2050.org)
Transport2
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)
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)
Assembly1
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)
Form2
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)
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)
Cells3
In vivo, cells get around this kinetic barrier by using various proteins to aid microtubule nucleation. (wikipedia.org)
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)
Growth1
The γ-TuRC also acts as a cap of the (−) end while the microtubule continues growth from its (+) end. (wikipedia.org)
Main1
2016). Consistently, mitotic delay, premature differentiation, and apoptosis have all been observed for centrosome defects in mouse models of main microcephaly (Insolera et al. (climat2050.org)