Academic literature on the topic 'Microtubules. Mitosis'
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Journal articles on the topic "Microtubules. Mitosis"
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Adib, Rozita, Jessica M. Montgomery, Joseph Atherton, Laura O’Regan, Mark W. Richards, Kees R. Straatman, Daniel Roth, et al. "Mitotic phosphorylation by NEK6 and NEK7 reduces the microtubule affinity of EML4 to promote chromosome congression." Science Signaling 12, no. 594 (August 13, 2019): eaaw2939. http://dx.doi.org/10.1126/scisignal.aaw2939.
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EML4 is a microtubule-associated protein that promotes microtubule stability. We investigated its regulation across the cell cycle and found that EML4 was distributed as punctate foci along the microtubule lattice in interphase but exhibited reduced association with spindle microtubules in mitosis. Microtubule sedimentation and cryo–electron microscopy with 3D reconstruction revealed that the basic N-terminal domain of EML4 mediated its binding to the acidic C-terminal tails of α- and β-tubulin on the microtubule surface. The mitotic kinases NEK6 and NEK7 phosphorylated the EML4 N-terminal domain at Ser144 and Ser146 in vitro, and depletion of these kinases in cells led to increased EML4 binding to microtubules in mitosis. An S144A-S146A double mutant not only bound inappropriately to mitotic microtubules but also increased their stability and interfered with chromosome congression. In addition, constitutive activation of NEK6 or NEK7 reduced the association of EML4 with interphase microtubules. Together, these data support a model in which NEK6- and NEK7-dependent phosphorylation promotes the dissociation of EML4 from microtubules in mitosis in a manner that is required for efficient chromosome congression.
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Jordan, M. A., D. Thrower, and L. Wilson. "Effects of vinblastine, podophyllotoxin and nocodazole on mitotic spindles. Implications for the role of microtubule dynamics in mitosis." Journal of Cell Science 102, no. 3 (July 1, 1992): 401–16. http://dx.doi.org/10.1242/jcs.102.3.401.
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Inhibition of mitosis by many drugs that bind to tubulin has been attributed to depolymerization of microtubules. However, we found previously that low concentrations of vinblastine and vincristine blocked mitosis in HeLa cells with little or no depolymerization of spindle microtubules, and spindles appeared morphologically normal or nearly normal. In the present study, we characterized the effects of vinblastine, podophyllotoxin and nocodazole over broad concentration ranges on mitotic spindle organization in HeLa cells. These three drugs are known to affect the dynamics of microtubule polymerization in vitro and to depolymerize microtubules in cells. We wanted to probe further whether mitotic inhibition by these drugs is brought about by a more subtle effect on the microtubules than net microtubule depolymerization. We compared the effects of vinblastine, podophyllotoxin and nocodazole on the organization of spindle microtubules, chromosomes and centrosomes, and on the total mass of microtubules. Spindle organization was examined by immunofluorescence microscopy, and microtubule polymer mass was assayed on isolated cytoskeletons by a quantitative enzyme-linked immunoadsorbence assay for tubulin. As the drug concentration was increased, the organization of mitotic spindles changed in the same way with all three drugs. The changes were associated with mitotic arrest, but were not necessarily accompanied by net microtubule depolymerization. With podophyllotoxin, mitotic arrest was accompanied by microtubule depolymerization. In contrast, with vinblastine and nocodazole, mitotic arrest occurred in the presence of a full complement of spindle microtubules. All three drugs induced a nearly identical rearrangement of spindle microtubules, an increasingly aberrant organization of metaphase chromosomes, and fragmentation of centrosomes. The data suggest that these anti-mitotic drugs block mitosis primarily by inhibiting the dynamics of spindle microtubules rather than by simply depolymerizing the microtubules.
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Vedrenne, Cécile, Dieter R. Klopfenstein, and Hans-Peter Hauri. "Phosphorylation Controls CLIMP-63–mediated Anchoring of the Endoplasmic Reticulum to Microtubules." Molecular Biology of the Cell 16, no. 4 (April 2005): 1928–37. http://dx.doi.org/10.1091/mbc.e04-07-0554.
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The microtubule-binding 63-kDa cytoskeleton-linking membrane protein (CLIMP-63) is an integral membrane protein that links the endoplasmic reticulum (ER) to microtubules. Here, we tested whether this interaction is regulated by phosphorylation. Metabolic labeling with 32P showed that CLIMP-63 is a phosphoprotein with increased phosphorylation during mitosis. CLIMP-63 of mitotic cells is unable to bind to microtubules in vitro. Mitotic phosphorylation can be prevented by mutation of serines 3, 17, and 19 in the cytoplasmic domain of CLIMP-63. When these residues are mutated to glutamic acid, and hence mimic mitotic phosphorylation, CLIMP-63 does no longer bind to microtubules in vitro. Overexpression of the phospho-mimicking mitotic form of CLIMP-63 in interphase cells leads to a collapse of the ER around the nucleus, leaving the microtubular network intact. The results suggest that CLIMP-63–mediated stable anchoring of the ER to microtubules is required to maintain the spatial distribution of the ER during interphase and that this interaction is abolished by phosphorylation of CLIMP-63 during mitosis.
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Roychoudhury, Sonali, and Martha J. Powell. "Ultrastructure of mitosis in the algal parasitic fungus Polyphagus euglenae." Canadian Journal of Botany 69, no. 10 (October 1, 1991): 2201–14. http://dx.doi.org/10.1139/b91-277.
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Ultrastructure of mitosis in the parasitic fungus, Polyphagus euglenae, was investigated with emphasis on centrosome structure and prophase events. The interphase centrosome included a diplosome, scattered electron-dense satellites, and multiple ring-shaped microtubule foci. As centrosomes separated during prophase, microtubular arrays extended between the replicated centrosomes and radiated out along the outer surface of the nuclear envelope. The asymmetric configuration of these microtubular arrays suggests that intersecting microtubules provide tension forces on elongating centrosome to centrosome microtubules during centrosome separation. After centrosome migration, multiple microtubule foci appeared to fuse into crescent-shaped microtubule organizing centers. Condensing chromatin was concentrated in the region of the future equatorial plane of the mitotic spindle prior to the appearance of discontinuities in the nuclear envelope and incursion of the spindle. The nucleolus fragmented during prometaphase, and fragments were discarded with the interzonal region during telophase. Nucleoli appeared in daughter nuclei before chromatin became diffuse. Similarities in the mitotic apparatus of P. euglenae with that previously reported for Monoblepharella sp. support a phylogenetic affinity between members of the orders Chytridiales and Monoblepharidales. Key words: mitosis, Polyphagus euglenae, Chytridiales, centrosomes, phylogeny, ultrastructure.
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Andreassen, P. R., and R. L. Margolis. "Microtubule dependency of p34cdc2 inactivation and mitotic exit in mammalian cells." Journal of Cell Biology 127, no. 3 (November 1, 1994): 789–802. http://dx.doi.org/10.1083/jcb.127.3.789.
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The protein kinase inhibitor 2-aminopurine induces checkpoint override and mitotic exit in BHK cells which have been arrested in mitosis by inhibitors of microtubule function (Andreassen, P. R., and R. L. Margolis. 1991. J. Cell Sci. 100:299-310). Mitotic exit is monitored by loss of MPM-2 antigen, by the reformation of nuclei, and by the extinction of p34cdc2-dependent H1 kinase activity. 2-AP-induced inactivation of p34cdc2 and mitotic exit depend on the assembly state of microtubules. During mitotic arrest generated by the microtubule assembly inhibitor nocodazole, the rate of mitotic exit induced by 2-AP decreases proportionally with increasing nocodazole concentrations. At nocodazole concentrations of 0.12 microgram/ml or greater, 2-AP induces no apparent exit through 75 min of treatment. In contrast, 2-AP brings about a rapid exit (t1/2 = 20 min) from mitotic arrest by taxol, a drug which causes inappropriate overassembly of microtubules. In control mitotic cells, p34cdc2 localizes to kinetochores, centrosomes, and spindle microtubules. We find that efficient exit from mitosis occurs under conditions where p34cdc2 remains associated with centrosomal microtubules, suggesting it must be present on these microtubules in order to be inactivated. Mitotic slippage, the natural reentry of cells into G1 during prolonged mitotic block, is also microtubule dependent. At high nocodazole concentrations slippage is prevented and mitotic arrest approaches 100%. We conclude that essential components of the machinery for exit from mitosis are present on the mitotic spindle, and that normal mitotic exit thereby may be regulated by the microtubule assembly state.
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Masson, D., and T. E. Kreis. "Binding of E-MAP-115 to microtubules is regulated by cell cycle-dependent phosphorylation." Journal of Cell Biology 131, no. 4 (November 15, 1995): 1015–24. http://dx.doi.org/10.1083/jcb.131.4.1015.
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Expression levels of E-MAP-115, a microtubule-associated protein that stabilizes microtubules, increase with epithelial cell polarization and differentiation (Masson and Kreis, 1993). Although polarizing cells contain significant amounts of this protein, they can still divide and thus all stabilized microtubules must disassemble at the onset of mitosis to allow formation of the dynamic mitotic spindle. We show here that binding of E-MAP-115 to microtubules is regulated by phosphorylation during the cell cycle. Immunolabeling of HeLa cells for E-MAP-115 indicates that the protein is absent from microtubules during early prophase and progressively reassociates with microtubules after late prophase. A fraction of E-MAP-115 from HeLa cells released from a block at the G1/S boundary runs with higher apparent molecular weight on SDS-PAGE, with a peak correlating with the maximal number of cells in early stages of mitosis. E-MAP-115 from nocodazole-arrested mitotic cells, which can be obtained in larger amounts, displays identical modifications and was used for further biochemical characterization. The level of incorporation of 32P into mitotic E-MAP-115 is about 15-fold higher than into the interphase protein. Specific threonine phosphorylation occurs in mitosis, and the amount of phosphate associated with serine also increases. Hyperphosphorylated E-MAP-115 from mitotic cells cannot bind stably to microtubules in vitro. These results suggest that phosphorylation of E-MAP-115 is a prerequisite for increasing the dynamic properties of the interphase microtubules which leads to the assembly of the mitotic spindle at the onset of mitosis. Microtubule-associated proteins are thus most likely key targets for kinases which control changes in microtubule dynamic properties at the G2- to M-phase transition.
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Gable, Alyssa, Minhua Qiu, Janel Titus, Sai Balchand, Nick P. Ferenz, Nan Ma, Elizabeth S. Collins, et al. "Dynamic reorganization of Eg5 in the mammalian spindle throughout mitosis requires dynein and TPX2." Molecular Biology of the Cell 23, no. 7 (April 2012): 1254–66. http://dx.doi.org/10.1091/mbc.e11-09-0820.
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Kinesin-5 is an essential mitotic motor. However, how its spatial–temporal distribution is regulated in mitosis remains poorly understood. We expressed localization and affinity purification–tagged Eg5 from a mouse bacterial artificial chromosome (this construct was called mEg5) and found its distribution to be tightly regulated throughout mitosis. Fluorescence recovery after photobleaching analysis showed rapid Eg5 turnover throughout mitosis, which cannot be accounted for by microtubule turnover. Total internal reflection fluorescence microscopy and high-resolution, single-particle tracking revealed that mEg5 punctae on both astral and midzone microtubules rapidly bind and unbind. mEg5 punctae on midzone microtubules moved transiently both toward and away from spindle poles. In contrast, mEg5 punctae on astral microtubules moved transiently toward microtubule minus ends during early mitosis but switched to plus end–directed motion during anaphase. These observations explain the poleward accumulation of Eg5 in early mitosis and its redistribution in anaphase. Inhibition of dynein blocked mEg5 movement on astral microtubules, whereas depletion of the Eg5-binding protein TPX2 resulted in plus end–directed mEg5 movement. However, motion of Eg5 on midzone microtubules was not altered. Our results reveal differential and precise spatial and temporal regulation of Eg5 in the spindle mediated by dynein and TPX2.
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Rogers, Stephen L., Gregory C. Rogers, David J. Sharp, and Ronald D. Vale. "Drosophila EB1 is important for proper assembly, dynamics, and positioning of the mitotic spindle." Journal of Cell Biology 158, no. 5 (September 2, 2002): 873–84. http://dx.doi.org/10.1083/jcb.200202032.
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EB1 is an evolutionarily conserved protein that localizes to the plus ends of growing microtubules. In yeast, the EB1 homologue (BIM1) has been shown to modulate microtubule dynamics and link microtubules to the cortex, but the functions of metazoan EB1 proteins remain unknown. Using a novel preparation of the Drosophila S2 cell line that promotes cell attachment and spreading, we visualized dynamics of single microtubules in real time and found that depletion of EB1 by RNA-mediated inhibition (RNAi) in interphase cells causes a dramatic increase in nondynamic microtubules (neither growing nor shrinking), but does not alter overall microtubule organization. In contrast, several defects in microtubule organization are observed in RNAi-treated mitotic cells, including a drastic reduction in astral microtubules, malformed mitotic spindles, defocused spindle poles, and mispositioning of spindles away from the cell center. Similar phenotypes were observed in mitotic spindles of Drosophila embryos that were microinjected with anti-EB1 antibodies. In addition, live cell imaging of mitosis in Drosophila embryos reveals defective spindle elongation and chromosomal segregation during anaphase after antibody injection. Our results reveal crucial roles for EB1 in mitosis, which we postulate involves its ability to promote the growth and interactions of microtubules within the central spindle and at the cell cortex.
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Osmani, Aysha H., Jonathan Davies, C. Elizabeth Oakley, Berl R. Oakley, and Stephen A. Osmani. "TINA Interacts with the NIMA Kinase in Aspergillus nidulans and Negatively Regulates Astral Microtubules during Metaphase Arrest." Molecular Biology of the Cell 14, no. 8 (August 2003): 3169–79. http://dx.doi.org/10.1091/mbc.e02-11-0715.
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The tinA gene of Aspergillus nidulans encodes a protein that interacts with the NIMA mitotic protein kinase in a cell cycle-specific manner. Highly similar proteins are encoded in Neurospora crassa and Aspergillus fumigatus. TINA and NIMA preferentially interact in interphase and larger forms of TINA are generated during mitosis. Localization studies indicate that TINA is specifically localized to the spindle pole bodies only during mitosis in a microtubule-dependent manner. Deletion of tinA alone is not lethal but displays synthetic lethality in combination with the anaphase-promoting complex/cyclosome mutation bimE7. At the bimE7 metaphase arrest point, lack of TINA enhanced the nucleation of bundles of cytoplasmic microtubules from the spindle pole bodies. These microtubules interacted to form spindles joined in series via astral microtubules as revealed by live cell imaging. Because TINA is modified and localizes to the spindle pole bodies at mitosis, and lack of TINA causes enhanced production of cytoplasmic microtubules at metaphase arrest, we suggest TINA is involved in negative regulation of the astral microtubule organizing capacity of the spindle pole bodies during metaphase.
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Tipton, Aaron R., Jonathan D. Wren, John R. Daum, Joseph C. Siefert, and Gary J. Gorbsky. "GTSE1 regulates spindle microtubule dynamics to control Aurora B kinase and Kif4A chromokinesin on chromosome arms." Journal of Cell Biology 216, no. 10 (August 18, 2017): 3117–32. http://dx.doi.org/10.1083/jcb.201610012.
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In mitosis, the dynamic assembly and disassembly of microtubules are critical for normal chromosome movement and segregation. Microtubule turnover varies among different mitotic spindle microtubules, dictated by their spatial distribution within the spindle. How turnover among the various classes of spindle microtubules is differentially regulated and the resulting significance of differential turnover for chromosome movement remains a mystery. As a new tactic, we used global microarray meta-analysis (GAMMA), a bioinformatic method, to identify novel regulators of mitosis, and in this study, we describe G2- and S phase–expressed protein 1 (GTSE1). GTSE1 is expressed exclusively in late G2 and M phase. From nuclear envelope breakdown until anaphase onset, GTSE1 binds preferentially to the most stable mitotic spindle microtubules and promotes their turnover. Cells depleted of GTSE1 show defects in chromosome alignment at the metaphase plate and in spindle pole integrity. These defects are coupled with an increase in the proportion of stable mitotic spindle microtubules. A consequence of this reduced microtubule turnover is diminished recruitment and activity of Aurora B kinase on chromosome arms. This decrease in Aurora B results in diminished binding of the chromokinesin Kif4A to chromosome arms.
Dissertations / Theses on the topic "Microtubules. Mitosis"
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Gallaud, Emmanuel. "Caractérisation du rôle d'Ensconsine / MAP7 dans la dynamique des microtubules et des centrosomes." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S004/document.
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La mitose est une étape essentielle du cycle cellulaire à l’issue de laquelle le génome répliqué de la cellule mère est ségrégé de façon équitable entre les deux cellules filles. Pour cela, la cellule assemble une structure hautement dynamique et composée de microtubules, appelée le fuseau mitotique. En plus d’assurer la bonne ségrégation des chromosomes, le fuseau mitotique détermine l’axe de division, un phénomène particulièrement important pour la division asymétrique où des déterminants d’identité cellulaire doivent être distribués de façon inéquitable entre les deux cellules filles. L’assemblage et la dynamique de ce fuseau sont finement régulés par de nombreuses protéines qui sont associées aux microtubules. Au cour de ma thèse, nous avons identifié 855 protéines constituant l’interactome des microtubules de l’embryon de Drosophile par spectrométrie de masse puis criblé par ARNi 96 gènes peu caractérisés pour un rôle en mitose dans le système nerveux central larvaire. Par cette approche, nous avons identifié 18 candidats sur la base de leur interaction aux microtubules et de leur phénotype mitotique, dont Ensconsine/MAP7. Nous avons montré qu’Ensconsine est capable de s’associer aux microtubules du fuseau et favorise leur polymérisation. De plus, les neuroblastes des larves mutantes présentent des fuseaux raccourcis et une durée de mitose prolongée. Ce délai en mitose est dû à une activation prolongée du point de contrôle du fuseau mitotique qui est essentiel pour une ségrégation correcte des chromosomes en l’absence d’Ensconsine. D’autres part, en association avec la Kinésine-1, son partenaire fonctionnel en interphase, nous avons montré qu’Ensconsine est également impliquée dans la séparation des centrosomes au cours de l’interphase. Ceci entraine une distribution aléatoire des centrosomes pères et fils dans cellules filles. Grâce à cette étude, nous avons révélé deux nouvelles fonctions pour Ensconsine : elle favorise la polymérisation des microtubules et participe donc à l’assemblage du fuseau mitotique et est impliquée, avec la Kinésine-1 dans la dynamique des centrosomesMitosis is a key step of the cell cycle that allows the mother cell to segregate its replicated genome equally into the two daughter cells. To do so, the cell assembles a highly dynamic structure composed of microtubules called the mitotic spindle. Additionally to its role in the faithful segregation of chromosomes, the mitotic spindle defines the axis of cell division. This phenomenon is particularly important for the asymmetric cell division in which cell fate determinants have to be unequally distributed between the two daughter cells. Spindle assembly and dynamics are subtly regulated by numerous microtubules-associated proteins. During my PhD, we identified using mass spectrometry, 855 proteins establishing the Drosophila embryo microtubule interactome. An RNAi screen was performed in the larval central nervous system for 96 poorly described genes, in order to identify new mitotic regulators. Based on microtubule interaction and mitotic phenotype, among 18 candidates we focused on Ensconsin/MAP7. We have shown that Ensconsin is associated with spindle microtubules and promotes their polymerization. Neuroblasts from mutant larvae display shorter spindles and a longer mitosis duration. This mitotic delay is a consequence of an extended activation of the spindle assembly checkpoint, which is essential for the proper chromosome segregation in the absence of Ensconsin. This study also showed that, in association with its interphase partner Kinesin-1, Ensconsin is involved in centrosome separation during interphase. As a result, mother and daughter centrosomes are randomly distributed between the daughter cells. In conclusion, we highlighted two news functions of Ensconsin : first, this protein promotes microtubule polymerization and is involved in spindle assembly ; second, Ensconsin and its partner Kinesin-1 regulate centrosome dynamics
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Barton, Richard Christopher. "Microtubules, mitosis and chromosome segregation in Candida albicans." Thesis, University of Kent, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.256985.
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Bouguenina, Mohammed El Habib. "La protéine SMYLE (Short MYomegalin Like EB1 binding protein) dans l'organisation d'un complexe centrosomal, la régulation de la nucléation et la stabilisation des microtubules : conséquences sur la migration et la division des cellules cancéreuses." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM5060.
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Les microtubules (MT) sont des polymères dynamiques ancrés par leurs extrémités moins aux centres de nucléation alors que leurs extrémités plus, explorent le cytoplasme, jusqu’à être stabilisées. Cette capture des extrémités permet l’organisation du réseau des MT. Les +TIP sont un groupe de protéines qui s’associent aux bouts plus des MT. EB1 est une protéine centrale dans le réseau des +TIP qui régule la dynamique des MT et leur interaction avec les structures d’ancrage des extrémités plus. Par protéomique ciblée, nous avons caractérisé l’interactome d’EB1, et mis en évidence un groupe de protéines, précédemment associées aux centres de nucléation incluant AKAP9, une protéine échafaudage pour les protéines kinases A (PKA), la protéine de la matrice péricentriolaire CDK5RAP2, et une isoforme courte de la myomégaline que nous avons appelé SMYLE (Short MYomegalin Like EB1 binding protein). La cartographie moléculaire a permis de montrer que ces protéines formaient un complexe organisé de manière hiérarchique. Nous avons observé que l’association transitoire deLa protéine SMYLE (Short MYomegalin Like EB1 binding protein )dans l'organisation d'un complexe centrosomal, la régulation de la nucléation et la stabilisation des microtubules : conséquences sur la migration et la division des cellules cancéreuses avec les MT néo-nucléés au centrosome favorisait la nucléation et l’acétylation des MT. De manière notable, la déplétion de SMYLE aboutissait à un défaut de nucléation, mais aussi de la capture corticale des MT. Ces défauts dans l’organisation des MT étaient associés à une baisse notable de la migration des cellules de carcinome mammaire et à des anomalies mitotiques. Nos résultats nous permettent de proposer que SMYLE fait partie d’un complexe centrosomale, qui favorise l’assemblage ou la stabilité des microtubules néo-nucléés, contribuant ainsi à des processus majeurs pour le développement tumoralMicrotubules (MT) are dynamic polymers anchored by their minus ends at the MT organizing centers while their highly dynamic plus end explores the cytoplasm until it get stabilized. This plus end capture allows the organization of the MT network. +TIPs are a group of proteins that share the commonality to associate either directly or indirectly to MT plus ends. EB1 is a central protein of the +TIP network that regulates MT dynamics and their interactions with plus end anchoring structures. Using targeted proteomics, we have characterized the EB1 interactome and revealed a set of protein previously shown to associate with the nucleating centers that included AKAP9 an anchoring protein for protein kinase A (PKA), the pericentriolar matrix protein CDK5RAP2 and a short Myomegalin isoform that we named SMYLE (Short MYomegalin Like EB1 binding protein). Molecular mapping revealed that the proteins formed a hierarchically organized complex. We have observed that the transient association of SMYLE to the newly nucleated MTs at the centrosome favored the nucleation and acetylation. Interestingly, SMYLE depletion led to MT nucleation defects, but also a disruption of cortical MT capture. These defects in the MT network were associated with a steep fall in the migratory potential of breast cancer cells and mitotic abnormalities. Our results allow proposing that SMYLE belongs to centrosomal supramolecular complex that favors the assembly and stability of newly nucleated MTs, thus contributing to major processes in tumor development
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Vasileva, Vanya. "Kinetochore-derived microtubules : from molecular regulation to their role in mitosis." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/7fc60a5c-2fc1-43ef-87ca-4dc20de2200b.
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To maintain genetic integrity in cell division, replicated chromosomes must be segregated accurately into newly formed daughter cells. The faithful segregation of sister chromatids is a crucial event in cell proliferation since it ensures maintenance of a stable set of chromosomes that is critical for the genetic integrity of the daughter cells. Mistakes in sister chromatid segregation have been related to chromosome instability and aneuploidy characteristic of a variety of human diseases, such as cancers and congenital anomalies. During cell division, spindle-pole microtubules (MTs) must capture kinetochores (KTs) so that the chromosomes can be loaded on the mitotic spindle. However, it remains a mystery how spindle-pole MTs can locate KTs with high efficiency, within realistic capture times (Wollman et al. 2005). The appearance of MTs at KTs is correlated with their capture, which is consistent with KT-derived MTs facilitating the initial encounter of KTs by spindle-pole MTs (Kitamura et al. 2010). However, so far it has been difficult to establish a causal relationship between the appearance of KT-derived MTs and efficient KT capture. It has also been unclear how much contribution KT-derived MTs make to efficient KT capture by spindle-pole MTs. Here we show that a MT-associated protein Stu1CLASP is a good molecular tool to study the role of KT-derived MTs. Depletion of Stu1 protein abolished both localisation of the microtubule polymerase Stu2XMAP215 from KTs, and MT/tubulin nucleation at KTs, without affecting KT assembly (i.e. the ability of KTs to interact with spindle-pole MTs) or generation of spindle-pole MTs. Abolishing these KT-derived MTs in Stu1-depleted cells led to a delay in KT capture with an increase in the average capture time. To test whether KT-derived MTs were solely responsible for this delay in KT capture, we developed a mathematical model to recapitulate the roles of KT-derived MTs in Stu1-depleted cells. The model suggested that Stu1-depletion indeed delays KT capture due to a lack of KT-derived MTs. Our results also revealed the extent to which KT-derived MTs contribute to a rapid KT capture by spindle-pole MTs. Furthermore we showed that, after initial KT capture, KT-associated Stu1CLASP and Stu2XMAP215 are required to regulate dynamics of their associated spindle-pole MTs. Removal of Stu1CLASP and Stu2XMAP215 from KTs lead to defects in KT-dependent switch from MT depolymerisation to polymerisation (rescue). Interfering with KT-dependent MT rescue would compromise the maintenance of the KT–MT interaction. Our study reveals that KT-derived MTs facilitate efficient KT capture by spindle-pole MTs. Stu1CLASP promotes MT generation at KTs by recruiting a MT polymerase Stu2XMAP215. Afterwards, Stu2XMAP215 recruitment by Stu1CLASP to KTs is also important for MT rescue and sustained KT–MT interaction. Thus, we reveal crucial regulatory mechanisms of KT–MT interaction in early stages of mitosis.
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Farrell, Megan Christine. "Deciphering the Role of Kinetochores and Microtubules During Interphase and Mitosis in Toxoplasma Gondii." Thesis, Boston College, 2014. http://hdl.handle.net/2345/3824.
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Thesis advisor: Marc-Jan GubbelsThe obligate intracellular parasite Toxoplasma gondii exhibits closed mitosis, as chromosome segregation occurs with the confines of the nuclear envelope. Distinct structural changes are absent during mitosis, as the nucleolus is maintained and condensation of chromosomes is largely restricted. Moreover, the centromeres are clustered and remain persistently associated with the centrocone (spindle pole). To elucidate the process of chromosome segregation during mitosis in the parasite, the role of kinetochores and microtubules was examined. Localization studies of the functionally conserved kinetochore proteins TgNuf2 and TgNdc80 revealed that clustered kinetochores colocalize with clustered centromeres at the centrocone throughout the cell cycle. Pharmacological disruption of microtubules resulted in partial loss of clustering, which indicates spindle microtubules are necessary, but not strictly required for this process. Furthermore, the generation of a conditional TgNuf2 knockdown revealed this kinetochore protein is essential for chromosome segregation but dispensable for clustering of centromeres, which remain associated with the centrocone. Moreover, in the absence of TgNuf2 the centrosome behaves normally, but looses its association with the centrocone. Further analysis of this phenotype revealed that the centrocone is devoid of spindle microtubules following depletion of this essential kinetochore protein. Examination of tubulin localization dynamics through parasite development showed that the initiation of spindle microtubules occurs at the basal region of the nucleus prior to centrosome duplication. Furthermore, acetylation of α-tubulin, a posttranslational modification associated with microtubule stability, was confirmed to be specifically associated with stabilization of the spindle microtubules following comigration of the centrocone and centrosome to the apical end of the nucleus. Collectively, these data demonstrate that the persistent association of clustered centromeres with the centrocone is independent of spindle microtubules. These discoveries are contributing unprecedented details to chromosome anchoring and segregation during the cell cycle in this protozoan parasite
Thesis (PhD) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Biology
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Ramírez, Cota Rosa María. "Dissecting the function of γTuRC subunits in microtubule nucleation and organization." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/398851.
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The depletion of MZT1 in human cells causes severe mitotic spindle defects. Depleted cells lack centrosomal γ-tubulin and arrest in mitosis with a monopolar spindle configuration. Similarly, double deletion mutants of the plant MZT1 orthologs GIP1a and GIP1b are embryonic lethal due to abnormal spindle microtubule distribution and chromosome mis-segregation. Moreover GIP1a and GIP1b were shown to localize to active nucleation sites in the interphase cortical microtubule array. MZT1 function is conserved in fission yeast, where it interacts with GCP3, and is an essential component for the recruitment of the γ-tubulin complex to the spindle pole body, the centrosome equivalent, but not for assembly of the γ-tubulin complex. However, the molecular mechanisms underlying these effects remain unknown. The main goal of this project is to study how MZT1 regulates γTuRC to control MT nucleation and organization.
In this work I confirm that in human cells MZT1 is a subunit of the γTuRC and is required for the targeting of the γTuRC to centrosomes and for proper spindle formation. By sucrose gradient fractionation I found that in mammalian cells, MZT1 is not required to assemble the γTuRC. Interestingly, I found that MZT1 is necessary for the interaction of the γTuRC with the targeting factor NEDD1/GCPWD.
While in plants and in fission yeast MZT1 interacts with the N-terminal region of GCP3, I found that in mammalian cells MZT1 interacts with a conserve motif at the N-terminal extension of GCP2, GCP3, GCP5 and GCP6. Furthermore, by immunoprecipitation of FLAG-tagged GCPs MZT1 binding motif mutants, I found that the mutants can be integrated into the γTuRC but lost the interaction with GCP-WD and fail to be targeted to the centrosomes
To study the role of MZT1 in MT nucleation I performed a MT regrowth experiment with U2OS cells over expressing the CDK5RAP2 nucleation-activating fragment (CDK5RAP2 CM1) and depleted of MZT1. The MT nucleation induced by CDK5RAP2 was lost upon the depletion of MZT1, suggesting that MZT1 in required for the MT nucleation activation mediated by CDK5RAP2.
In summary MZT1 is required for all γTuRC-dependent functions including centriole duplication. MZT1 binds to a conserved motif present in the extended N-termini of GCP2, GCP3, GCP5 and GCP6, allowing specific recognition of fully assembled γTuRC. Binding of MZT1 primes γTuRC for interaction with the adapter NEDD1/GCP-WD for targeting γTuRC to centrosomes. In addition, MZT1-dependent priming is required for the CDK5RAP2 CM1 domain to activate γTuRC nucleation activity. Thus, by enabling specific recognition of γTuRC by targeting and activation factors, MZT1 spatially controls microtubule nucleationEn las células humanas la depleción de MZT1 provoca graves defectos del huso mitótico. Las células deplecionadas carecen de γ-tubulina centrosomal y presentan una detención de la mitosis con una configuración monopolar del huso mitótico. Del mismo modo, mutantes de deleción dobles de planta MZT1 con sus ortólogos GIP1a y GIP1b son letales para los embriones debido a la anormal distribución de los microtúbulos del huso mitótico y la mala segregación del cromosoma. Además, GIP1a y GIP1b localizan en sitios de nucleación activos de los microtúbulos corticales. La función de MZT1 se conserva en la levadura de fisión, donde interactúa con GCP3, y es un componente esencial para el reclutamiento del complejo de γ-tubulina en el huso polar del cuerpo apical, el equivalente al centrosoma, pero no para el montaje de la γ-tubulina compleja. Sin embargo, los mecanismos moleculares que subyacen a estos efectos siguen siendo desconocidos. El objetivo principal de este proyecto es estudiar cómo MZT1 regula la actividad del γTuRC en la nucleación y organización de los microtúbulos. En este trabajo encontré que MZT1 es necesaria para todas las funciones γTuRC-dependientes, como la duplicación de centríolos. MZT1 se une a un motivo conservado presente en la N-terminales extendida de GCP2, GCP3, GCP5 y GCP6, lo que permite el reconocimiento específico de γTuRC totalmente ensamblado. La unión de MZT1 al γTuRC “prepara” al complejo para la interacción con el adaptador NEDD1/GCP-WD para la orientación γTuRC a los centrosomas. Además, se requieren esta “preparación” para activar la actividad nucleadora del γTuRC mediada por CDK5RAP2 CM1. Por lo tanto, al permitir el reconocimiento específico de γTuRC por los factores de reclutamiento y los factores de activación, se observa que la MZT1 controla espacialmente la nucleación de microtúbulos.
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Kuhnert, Oliver. "Charakterisierung der neuen centrosomalen Proteine CP148 und CP55 in Dictyostelium discoideum." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2012/5994/.
Full textAbstract:
Das im Cytosol liegende Dictyostelium Centrosom ist aus einer geschichteten Core-Region aufgebaut, die von einer Mikrotubuli-nukleierenden Corona umgeben ist. Zudem ist es über eine spezifische Verbindung eng an den Kern geknüpft und durch die Kernmembran hindurch mit den geclusterten Centromeren verbunden. Beim G2/M Übergang dissoziiert die Corona vom Centrosom und der Core verdoppelt sich so dass zwei Spindelpole entstehen. CP55 und CP148 wurden in einer Proteom-Analyse des Centrosoms identifiziert. CP148 ist ein neues coiled-coil Protein der centrosomalen Corona. Es zeigt eine zellzyklusabhängige An- und Abwesenheit am Centrosom, die mit der Dissoziation der Corona in der Prophase und ihrer
Neubildung in der Telophase korreliert. Während der Telophase erschienen in GFP-CP148 exprimierenden Zellen viele, kleine GFP-CP148-Foci im Cytoplasma, die zum Teil miteinander fusionierten und zum Centrosom wanderten. Daraus resultierte eine hypertrophe Corona in Zellen mit starker GFP-CP148 Überexpression. Ein Knockdown von CP148 durch RNAi führte zu einem Verlust der Corona und einem ungeordneten Interphase Mikrotubuli-Cytoskelett. Die Bildung der mitotischen Spindel und der astralen Mikrotubuli blieb davon unbeeinflusst. Das bedeutet, dass die Mikrotubuli-Nukleationskomplexe während der Interphase und Mitose über verschiedene Wege mit dem Core assoziiert sind. Des Weiteren
bewirkte der Knockdown eine Dispersion der Centromere sowie eine veränderte Sun1
Lokalisation in der Kernhülle. Somit spielt CP148 ebenso eine Rolle in der Centrosomen-Centromer-Verbindung. Zusammengefasst ist CP148 ein essentielles Protein für die Bildung und Organisation der Corona, welche wiederum für die Centrosom/Centromer Verbindung benötigt wird. CP55 wurde als Protein der Core-Region identifiziert und verbleibt während des Zellzyklus am Centrosom. Dort besitzt es strukturelle Aufgaben, da die Mehrheit der GFP-CP55 Moleküle in der Interphase keine Mobilität zeigten. Die GFP-CP55 Überexpression führte zur Bildung von überzähligen Centrosomen mit der üblichen Ausstattung an Markerproteinen der Corona und des Cores. CP55 Knockout-Zellen waren durch eine erhöhte Ploidie, eine weniger strukturierte und leicht vergrößerte Corona sowie
zusätzliche cytosolische Mikrotubuli-organisierende Zentren charakterisiert. Letztere entstanden in der Telophase und enthielten nur Corona- aber keine Core-Proteine. In CP55 k/o Zellen erfolgte die Rekrutierung des Corona-Organisators CP148 an den Spindelpol bereits in der frühen Metaphase anstatt, wie üblich, erst in der Telophase. Außerdem zeigten die Knockout-Zellen Wachstumsdefekte, deren Grund vermutlich Schwierigkeiten bei der Centrosomenverdopplung in der Prophase durch das Fehlen von CP55 waren. Darüber hinaus konnten die Knockout-Zellen phagozytiertes Material nicht verwerten, obwohl der Vorgang der Phagozytose nicht beeinträchtigt war. Dieser Defekt kann dem im CP55 k/o auftretenden dispergierten Golgi-Apparat zugeschrieben werden.The Dictyostelium centrosome consists of a layered core structure surrounded by a microtubule-nucleating corona. A tight linkage through the nuclear envelope connects the cytosolic centrosome with the clustered centromeres within the nuclear matrix. At G2/M the corona dissociates, and the core structure duplicates yielding two spindle poles. The two proteins CP148 and CP55 were discovered in a proteomic analysis of Dictyostelium centrosomes. CP148 is a novel coiled-coil protein of the centrosomal corona. GFP-CP148 exhibited cell cycle dependent presence and absence at the centrosome, which correlates with dissociation of the corona in prophase and its reformation in late telophase. During telophase, GFP-CP148 formed cytosolic foci, which coalesced and joined the centrosome. This explains the hypertrophic appearance of the corona upon strong overexpression of GFP-CP148. Depletion of CP148 by RNAi caused virtual loss of the corona and disorganization of interphase microtubules. Surprisingly, formation of the mitotic spindle and astral microtubules was unaffected. Thus, microtubule nucleation complexes associate with centrosomal core components through different means during interphase and mitosis. Furthermore, CP148 RNAi caused dispersal of centromeres and altered Sun1 distribution at the nuclear envelope, suggesting a role of CP148 in the linkage between centrosomes and centromeres. Taken together, CP148 is an essential factor for the formation of the centrosomal corona, which in turn is required for centrosome/centromere linkage. As CP148, CP55 was also identified in a centrosomal proteome analysis. It is a component of the centrosomal core structure, and persists at the centrosome throughout the entire cell cycle. FRAP experiments revealed the majority of centrosomal GFP-CP55 is immobile indicating a structural task of CP55 at the centrosome. GFP-CP55 overexpression elicits supernumerary centrosomes containing the usual set of corona and core marker proteins. The CP55 null mutant is characterized by increased ploidy, a less structured, slightly enlarged corona, and by supernumerary, cytosolic MTOCs, containing only corona proteins and lacking a core structure. Live cell imaging showed that supernumerary MTOCs arise in telophase. Lack of CP55 also caused premature recruitment of the corona organizer CP148 to mitotic spindle poles, already in metaphase instead of telophase. Forces transmitted through astral microtubules may expel prematurely acquired or loosely attached corona fragments into the cytosol, where they act as independent MTOCs. CP55null cells were also impaired in growth, most probably due to difficulties in centrosome splitting during prophase. Furthermore, although they were still capable of phagocytosis, they appeared unable to utilize phagocytosed nutrients. This inability may be attributed to their disorganized Golgi apparatus.
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Guieu, Benjamin. "Synthèse de pyrroles polysubstitués par cyclisation à l'or : évaluation de l'activité de 3-arylpyrroles sur les microtubules." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S084/document.
Full textAbstract:
Des composés de type 3-arylpyrroles appelés pyakols ont montré une activité antimitotique sur des cellules tumorales murines, avec en particulier un effet sur les microtubules. Ce type d’activité biologique présentant un intérêt important en cancérologie, le travail présenté dans ce manuscrit est consacré à l’étude de ces hétérocycles. La première partie a pour objectif de développer une stratégie de synthèse permettant d’accéder efficacement au composé chef de file (pyakol I), basée sur la cyclisation d’intermédiaires α-amino-ynols catalysée par des complexes d’or. L’évaluation de l’activité biologique du pyakol I sur le cycle cellulaire et le cytosquelette de diverses lignées tumorales humaines a été réalisée. Les premiers résultats ont révélé une action originale du pyakol I sur le cytosquelette, provoquant une désorganisation du réseau de microtubules et un défaut de positionnement du fuseau mitotique. La séquence réactionnelle a ensuite été validée en l’appliquant pour la réalisation de modulations autour du motif 3-arylpyrrole ainsi que pour l’obtention de molécules marquées. La deuxième partie concerne un travail de méthodologie basée sur la réaction de cyclisation à l’or pour la synthèse de nouveaux pyrroles trifluorométhylés polysubstitués. La stratégie utilisant le trifluoroacétaldéhyde comme substrat de départ permet d’accéder à divers 3-trifluorométhylpyrroles avec de bons rendements, dans des conditions doucesA family of 3-arylpyrroles named pyakols have shown antimitotic properties on murine cell lines, displaying in particular an effect on microtubules. Given the interest of these properties in cancerology, this work is focused on these heterocycles. The objective of the first part was to develop a synthetic strategy based on the gold-catalysed cyclisation of α-amino-ynols intermediates in order to access the lead (Pyakol I). Then, the evaluation of the biological activity of this molecule on the cell cycle and on the cytoskeleton of various human tumoral cell lines was carried out. The first results revealed an original effect on the organization of the microtubules network and the positioning of the mitotic spindle. The developed strategy was then validated by modulating the 3-arylpyrrole moiety on diverse positions, and used for the synthesis of labelled derivatives. The second part of this manuscript focused on the development of a methodology to synthesize new polysubstituted 3-trifluoromethylpyrroles, based on the gold-catalyzed cyclisation reaction. Using trifluoroacetaldehyde as building-block, various trifluoromethylated pyrroles were obtained in mild conditions with good yields
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Argenty, Jérémy. "Rôles dans les lymphocytes T de la protéine Lis1, un régulateur de la dynamique des microtubules dépendante de la dynéine." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30123/document.
Full textAbstract:
Les récepteurs d'antigènes des lymphocytes T (TCR) sont assemblés au cours du développement précoce de ces cellules dans le thymus suite à des recombinaisons complexes de gènes. Le réarrangement d'une chaine beta des TCR fonctionnelle (pré-TCR) déclenche des voies de signalisation intracellulaires qui entrainent la survie, l'expansion et la maturation des thymocytes. Par ailleurs, l'engagement des TCR à la surface des lymphocytes T (LT) matures par des antigènes conduit également à des cycles de prolifération qui permettent le développement de réponses immunitaires efficaces. Ces évènements cellulaires s'accompagnent de remaniements importants du réseau de microtubules et une redistribution des moteurs moléculaires, tels que la dynéine, qui véhiculent les structures cellulaires sur ces réseaux. Les mécanismes moléculaires et les conséquences physiologiques de ces remaniements sont peu connus dans les LT. Lis1 est un régulateur de la dynéine qui est mis à contribution dans la migration neuronale et la prolifération des cellules souches au cours du développement neural. Son rôle au sein du tissu lymphoïde est peu connu. Dans ce travail, nous avons utilisé des modèles de souris spécifiquement déficients en Lis1 dans les LT afin d'étudier les fonctions moléculaires, cellulaires et physiologiques de cette protéine dans ces cellules. Nous montrons que Lis1 joue un rôle essentiel dans le développement précoce des LT et dans l'homéostasie des LT matures. La déficience en Lis1 n'affecte pas le réarrangement de la chaine beta ou les évènements de signalisation déclenchés par le pré-TCR ou le TCR. Cependant, la prolifération des thymocytes ayant passé la beta-sélection ou des LT matures dont le TCR a été engagé, est fortement impactée. L'analyse fine de la mitose indique que la déficience en Lis1 ralentit fortement le processus mitotique, contrarie les remaniements intracellulaires conduisant à la métaphase et entraîne la répartition asymétrique du matériel génétique dans les cellules filles. L'analyse des réseaux de microtubules montre que l'absence de Lis1 entraîne l'amplification du nombre de centrosomes et l'augmentation des cellules multipolaires au cours de la mitose. Enfin, nous montrons que Lis1 favorise l'interaction de la dynéine avec la dynactine, indiquant que Lis1 joue un rôle important dans les LT pour relier la dynéine aux structures cellulaires qu'elle véhicule. En conclusion, nous avons montré que Lis1 est importante dans la distribution du matériel génétique au cours de la prolifération des thymocytes doubles négatifs et des lymphocytes T périphériquesThe T cell receptor (TCR) is assembled during the early development of T lymphocytes in the thymus after complexe genetic recombinations. The rearrangement of a functional TCR beta-chain (pre-TCR) triggers intracellular signaling pathways that cause the survival, expansion and maturation of thymocytes. The commitment of the TCR to the surface of mature T cells after antigen recognition also leads to proliferation allowing the development of effective immune responses. These cellular events go along with significant reorganization of the microtubule networks and a redistribution of molecular motors, such as dynein, which transport the cellular structures via this network. The molecular mechanisms and physiological consequences of the reorganization are poorly understood in T cells. Lis1 is a dynein regulator involved in neuronal migration and stem cells proliferation during neural development. Its role in lymphoid tissue is still unknown. In this study, we used mouse models specifically Lis1-deficient in T cells to study the molecular, cellular and physiological functions of this protein in T cells. We identifiy that Lis1 plays an essential role in the early development of T cells and in the homeostasis of mature cells. Lis1 deficiency does not affect beta-chain rearrangement or signaling events triggered by pre-TCR or TCR, but leads to the blockage of thymocyte cell division that have undergone beta-selection or mature T cells stimulated. Fine analysis of mitosis indicates that the deficiency of Lis1 strongly slows down the mitotic process, counteracts the cell changes leading to the metaphase and leads to asymmetric distribution of the genetic material in the daughter cells. Microtubule networks analysis shows that the absence of Lis1 induces centrosomes amplification and increase of multipolar cells during mitosis. Finally, we show that Lis1 promotes the dynein-dynactin interaction, indicating that Lis1 plays an important role in T cells to bind dynein to the cell structures it carries. In conclusion, we here described that Lis1 is important for the distribution of genetic material during double negative thymocyte and peripheral lymphocyte proliferation
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Masoud, Kinda. "Caractérisation moléculaire et fonctionnelle des protéines GIPs (Gamma-tubulin complex protein 3-Interacting Proteins) d'Arabidopsis thaliana." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAJ011/document.
Full textAbstract:
Les microtubules constituent l’un des réseaux du cytosquelette des cellules eucaryotes. Ils jouent un rôle central dans de multiples fonctions comme la division cellulaire, les trafics intracellulaires et la morphogenèse cellulaire. Chez les plantes supérieures, les microtubules (MTs) forment différents réseaux qui s'assemblent au cours du cycle cellulaire. Cette spécificité nécessite un recrutement régulé des complexes de nucléation des MTs à l’enveloppe nucléaire, au cortex et au niveau de MTs préexistants, qui sont des sites de nucléation caractérisés. L'équipe d’A.C. Schmit (IBMP, CNRS, Strasbourg), dans laquelle j'ai effectué mon travail de thèse, se focalise sur la caractérisation des complexes de nucléation des MTs (γ-TuRCs) et la régulation de l'assemblage du fuseau mitotique chez les plantes. Deux nouvelles protéines associées au γ-TuRC ont été mises en évidence par une interaction directe avec l'un de ses composants AtGCP3. Ces protéines, AtGIP1 et AtGIP2 (GCP3 Interacting Protein 1 et 2), sont très conservées au cours de l'évolution, mais leur fonction reste totalement inconnue. Mon travail a été consacré à la caractérisation de cette nouvelle classe de protéines dans le but de comprendre leur rôle. Nos résultats suggèrent que l'association des protéines GIPs aux γ-TuRCs participe à la régulation de leur activité et à la formation d'un fuseau mitotique robuste. Le profil de localisation des protéines GIPs au cours du cycle cellulaire et les phénotypes observés chez les mutants "perte de fonction" gip1gip2 indiquent que ces protéines interviennent dans le recrutement des γ-TuRCs, la nucléation des MTs, l’assemblage du fuseau mitotique, le déroulement du cycle cellulaire et l'organisation des méristèmes. L’étude des mécanismes de régulation de cette famille de protéines a été initiée. Nos résultats ont permis d’identifier GIP1comme un substrat de la kinase Aurora1 in vitro. Les résultats d’expérience de complémentation avec des phosphomutants GIP1 indiquent que la/les fonction(s) des GIPs pourrai(en)t être dépendante(s) de la phosphorylation par la kinase Aurora1, qui est un régulateur avéré du cycle cellulaire. L’ensemble de mes travaux a ainsi contribué à la caractérisation de nouveaux acteurs du cytosquelette microtubulaire. Une meilleure connaissance de leur réseau d'interaction (interactome) ainsi que l’étude de leur homologue humain pourraient ouvrir de nouvelles perspectives de recherche dans le contrôle de la division cellulaire et la lutte contre le cancerMicrotubules (MTs) constitute one of the cytoskeletal networks in eukaryotic cells. They are involved in various processes such as cell division, intracellular transport and cell morphogenesis. In higher plants, MTs can be organized into dynamic structures, which undergo continual assembly and disassembly during the cell cycle. This specificity requires the recruitment of the nucleation complexes of the MTs to the nuclear envelope, to the cortex and to pre-existing MTs. The work of A. C. Schmit’s team (IBMP, CNRS, Strasbourg), in which I did my thesis, focuses on the characterization of MT nucleation complexes (γ-TuRCs) and the regulation of mitotic spindle assembly in plants. We have identified small proteins interacting with Gamma-tubulin Complex Protein 3 (GCP) and named GIP1 and GIP2 (GCP3-Interacting Proteins). The aim of these studies was to characterize this new class of proteins in order to understand their role. It shows that GIPs are conserved among eukaryotes and suggests that their association with the γ-TuRC participates in the regulation of their activity and the formation of a robust mitotic spindle. The localization of GIPs during the cell cycle and the phenotypes observed in T-DNA insertional gip1gip2 double mutants indicatethat GIPs are required for the recruitment of γ-TuRCs, MT nucleation, spindle assembly, cell cycle regulation and stem cell maintenance. Likewise, in vitro assays showed that GIP1 is a novel substrate for Aurora kinase1, which is a well known cell cycle regulator. The results of complementation experiments with GIP1 phosphomutants indicate that the phosphorylation of GIPs may be required for their function(s). Altogether, our results have contributed to the characterization of a new class of proteins involved in MT nucleation/organization and functions. The study of the interaction network (interactome) of GIPs and oftheir homologues could open new ways of research in the control of cell division and in the fight against cancer
Books on the topic "Microtubules. Mitosis"
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Gagliardi, L. John. Electrostatic considerations in mitosis: Integrating physics and cell biology in mitosis. Bloomington, IN: Iuniverse Inc, 2009.
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Raemaekers, Tim. Nusap, a Novel Microtubule-Associated Protein (Map) Involved in Mitotic Spindle Organization. Leuven Univ Pr, 2003.
Find full textBook chapters on the topic "Microtubules. Mitosis"
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Roos, Urs-Peter, and Bruno Guhl. "Microtubules in Interphase and Mitosis of Cellular Slime Molds." In Biomechanics of Active Movement and Deformation of Cells, 73–107. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-83631-2_3.
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Molè-Bajer, Jadwiga, and A. S. Bajer. "Relation of F-actin Organization to Microtubules in Drug Treated Haemanthus Mitosis." In Protoplasma, 99–112. Vienna: Springer Vienna, 1988. http://dx.doi.org/10.1007/978-3-7091-9008-1_13.
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Bahmanyar, Shirin, W. James Nelson, and Angela I. M. Barth. "Role of APC and Its Binding Partners in Regulating Microtubules in Mitosis." In Advances in Experimental Medicine and Biology, 65–74. New York, NY: Springer New York, 2009. http://dx.doi.org/10.1007/978-1-4419-1145-2_6.
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Meunier, Sylvain, and Isabelle Vernos. "Microtubule Organization in Mitotic Cells." In The Microtubule Cytoskeleton, 1–26. Vienna: Springer Vienna, 2016. http://dx.doi.org/10.1007/978-3-7091-1903-7_1.
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De Brabander, M., F. Aerts, J. De Mey, G. Geuens, M. Moeremans, R. Nuydens, and R. Willebrords. "Microtubule Dynamics and the Mitotic Cycle: A Model." In Aneuploidy, 269–78. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2127-9_17.
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Zee, S. Y., and Aziz-Un-Nisa. "Mitosis and Colchicine Effects on Microtubule Organization in Isolated Generative Cells of Allamanda neriifolia." In Angiosperm Pollen and Ovules, 233–37. New York, NY: Springer New York, 1992. http://dx.doi.org/10.1007/978-1-4612-2958-2_37.
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Jordon, Mary Ann, and Leslie Wilson. "Microtubule Polymerization Dynamics, Mitotic Block, and Cell Death by Paclitaxel at Low Concentrations." In ACS Symposium Series, 138–53. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1995-0583.ch010.
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Lecland, Nicolas, and Jens Lüders. "Imaging and Quantifying the Dynamics of γ-Tubulin at Microtubule Minus Ends in Mitotic Spindles." In Methods in Molecular Biology, 63–75. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3542-0_5.
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Vantard, M., H. Stoeckel, P. Picquot, L. Van Eldik, and A. M. Lambert. "Calcium Ions and the Dynamics of the Microtubular Cytoskeleton During the Initiation and the Progression of Mitosis in Endosperm Cells." In Molecular and Cellular Aspects of Calcium in Plant Development, 375–77. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4613-2177-4_67.
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Girão, Hugo, and Helder Maiato. "Measurement of Microtubule Half-Life and Poleward Flux in the Mitotic Spindle by Photoactivation of Fluorescent Tubulin." In Methods in Molecular Biology, 235–46. New York, NY: Springer US, 2019. http://dx.doi.org/10.1007/978-1-0716-0219-5_15.
Full textConference papers on the topic "Microtubules. Mitosis"
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Pillai, Smitha R., Jonathan Nguyen, Joseph Johnson, Eric Haura, Domenico Coppola, and Srikumar Chellappan. "Abstract 3771: Tank-binding kinase 1 associates with centrosomes and regulates microtubule dynamics and mitosis." In Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.am2015-3771.
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Rohena, Cristina C., Jiangnan Peng, Tyler A. Johnson, Phillip Crews, and Susan L. Mooberry. "Abstract 4501: Diverse microtubule stabilizers cause differential expression of mitotic kinases leading to distinct centrosomal and mitotic defects." In Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1538-7445.am2013-4501.
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Ward, Tarsha L. "Abstract 2056: Molecular delineation of TIP150 function underlying kinetochore microtubule dynamics during mitotic chromosome segregation." In Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-2056.
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Carney, Bruce, Victoria Caruso, and Lynne Cassimeris. "Abstract C32: Stathmin depletion from cells lacking p53 delays mitotic entry by increasing microtubule stability during interphase." In Abstracts: Second AACR International Conference on Frontiers in Basic Cancer Research--Sep 14-18, 2011; San Francisco, CA. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.fbcr11-c32.
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Liu, Jun Jen, Chun Te Ho, Li Xi Yang, Yu Jia Chang, Tsan Zon Liu, and Po Li Wei. "Abstract 4424: Molecular mechanism study of a novel microtubule-binding agent-induced mitotic cell death of human hepatocellular carcinoma." In Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-4424.
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Florian, Stefan, Deepak R. Chittajallu, Rainer H. Kohler, James D. Orth, Peter K. Sorger, Ralph Weissleder, Gaudenz Danuser, and Timothy J. Mitchison. "Abstract A297: Microtubule targeting antimitotic drugs induce a lower mitotic arrest than clinically less effective antimitotic Eg5 inhibitors in mouse xenografts." In Abstracts: AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics--Oct 19-23, 2013; Boston, MA. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1535-7163.targ-13-a297.
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Pan, Zhi, and Lauren Gollahon. "Abstract 1081: The role of calcium in relationship of microtubule stabilization, mitotic arrest, and apoptosis induced by Taxol in breast cancer cells." In Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-1081.
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Sin, Eun Ah, Eun J. Sohn, Ji Hoon Jung, Duckgue Lee, Bonglee Kim, Duck-Beom Jung, Ji-Hyun Kim, Hyo-Jeong Lee, and Sung Hoon Kim. "Abstract 1740: SATB2 localizes to mitotic microtubules and centrosome of cell cycles and regulates G1 phase cell cycle via proteosomal-dependent CDK2 in SKOV-3 ovarian cancer cells." In Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1538-7445.am2013-1740.
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Subbarayalu, Panneerdoss, Subapriya Rajamanickam, Suryavathi Viswanadhapalli, Benjamin C. Onyeagucha, Vijay K. Eedunuri, Nicholas Dybdal-Hargreaves, Santosh Timilsina, et al. "Abstract 3658: A novel microtubule associated RNA binding protein matrin 3 act as a tumor suppressor by regulating mitotic spindle organizing proteins in triple negative breast cancers." In Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.am2016-3658.
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