CDK-1 inhibits meiotic spindle shortening and dynein-dependent spindle rotation
Cytoplasmic dynein is a large multi-subunit molecular motor that is required for many cellular processes including spindle positioning. In the nematode C. elegans, cytoplasmic dynein is required for positioning the acentrosomal female meiotic spindle at the cell cortex prior to anaphase chromosome segregation. This dynein-dependent event occurs at a precise time during meiosis and is under cell cycle control, requiring activation of the anaphase-promoting complex (APC). In this study, we treated metaphase-arrested embryos with a small molecule inhibitor and found that cyclin B/CDK-1, a cell cycle driver and APC substrate , inhibits dynein-dependent meiotic spindle positioning. Inhibition of CDK-1 results in increased microtubule binding of the dynein activator, dynactin, suggesting that cyclin B/CDK-1 inhibits dynein-dependent spindle positioning via reducing the microtubule binding affinity of dynactin. This novel mechanism of cell cycle dependent regulation of cytoplasmic dynein may be important of other dynein driven processes.
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