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Query: EC:3.6.4.4 (kinesin)
 5,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell multiplication requires sequestration of the duplicated and segregated genome into two daughter cells. The mitotic spindle is critical for orchestrating sister chromatid separation and division plane positioning. During anaphase, spindle microtubules become bundled to form the central spindle, which is essential for completion of cytokinesis. Central spindle assembly is mediated by a microtubule-associated protein and a kinesin-RhoGAP complex, both of which are regulated by phosphorylation/dephosphorylation. The central spindle also plays a role in cleavage furrow positioning, which appears to involve activation of RhoA. New results have provided some initial clues as to how furrow positioning is achieved. Particularly notable is the discovery that a protein activated by RhoA, formin, has actin nucleation activity.
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PMID:Cytokinesis: progress on all fronts. 1464 92

The C. elegans foregut (pharynx) has emerged as a powerful system to study organ formation during embryogenesis. Here I review recent advances regarding cell-fate specification and epithelial morphogenesis during pharynx development. Maternally-supplied gene products function prior to gastrulation to establish pluripotent blastomeres. As gastrulation gets under way, pharyngeal precursors become committed to pharyngeal fate in a process that requires PHA-4/FoxA and the Tbox transcription factors TBX-2, TBX-35, TBX-37 and TBX-38. Subsequent waves of gene expression depend on the affinity of PHA-4 for its target promoters, coupled with combinatorial strategies such as feed-forward and positive-feedback loops. During later embryogenesis, pharyngeal precursors undergo reorganization and a mesenchymal-to-epithelial transition to form the linear gut tube. Surprisingly, epithelium formation does not depend on cadherins, catenins or integrins. Rather, the kinesin ZEN-4/MKLP1 and CYK-4/RhoGAP are critical to establish the apical domain during epithelial polarization. Finally, I discuss similarities and differences between the nematode pharynx and the vertebrate heart.
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PMID:The C. elegans pharynx: a model for organogenesis. 1805 May 3

Cytokinesis in animal cells requires the central spindle and midbody, which contain prominent microtubule bundles. Centralspindlin, a heterotetrameric complex consisting of kinesin-6 and RhoGAP (Rho-family GTPase-activating protein) subunits, is essential for the formation of these structures. Centralspindlin becomes precisely localized to the central spindle, where it promotes the equatorial recruitment of important cytokinetic regulators. These include ECT2, the activator of the small GTPase RhoA, which controls cleavage furrow formation and ingression. Centralspindlin's own RhoGAP domain also contributes to furrow ingression. Finally, centralspindlin facilitates recruitment of the chromosome passenger complex and factors that control abscission. Despite the importance of localized accumulation of centralspindlin, the mechanism by which this motor protein complex suddenly concentrates to the center of interpolar microtubule bundles during anaphase is unclear. Here, we show that centralspindlin travels along central spindle microtubules as higher-order clusters. Clustering of centralspindlin is critical for microtubule bundling and motility along microtubules in vitro and for midbody formation in vivo. These data support a positive feedback loop of centralspindlin clustering and microtubule organization that may underlie its distinctive localization during cytokinesis.
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PMID:Clustering of centralspindlin is essential for its accumulation to the central spindle and the midbody. 1996 7

In cytokinesis, there is a lengthy interval between cleavage furrow ingression and abscission, during which the midbody microtubule bundle provides both structural support for a narrow intercellular bridge and a platform that orchestrates the biochemical preparations for abscission. It is currently unclear how the midbody structure is stably maintained during this period. Here, we report a novel role for the ADP-ribosylation factor 6 (ARF6) GTPase in the post-mitotic stabilisation of midbody. Centralspindlin kinesin-6/RhoGAP complex, a midbody component critical for both the formation and function of the midbody, assembles in a sharp band at the centre of the structure in a manner antagonised by 14-3-3 protein. We show that ARF6 competes with 14-3-3 for binding to centralspindlin such that midbodies formed by centralspindlin mutants that can bind 14-3-3 but not ARF6 frequently collapse before abscission. These data indicate a novel mechanism for the regulation of midbody dynamics in which ARF6 protects the compacted centralspindlin assembly from dissipation by 14-3-3.
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PMID:ARF6 GTPase protects the post-mitotic midbody from 14-3-3-mediated disintegration. 2258 Aug 24