PDF(Pubmed)
Abstract：
Precise segregation of chromosomes during mitosis requires assembly of a bipolar mitotic spindle followed by correct attachment of microtubules to the kinetochores. This highly spatiotemporally organized process is controlled by various mitotic kinases and molecular motors. We have recently shown that Casein Kinase 1 (CK1) promotes timely progression through mitosis by phosphorylating FAM110A leading to its enrichment at spindle poles. However, the mechanism by which FAM110A exerts its function in mitosis is unknown. Using structure prediction and a set of deletion mutants, we mapped here the interaction of the N- and C-terminal domains of FAM110A with actin and tubulin, respectively. Next, we found that the FAM110A-Δ40-61 mutant deficient in actin binding failed to rescue defects in chromosomal alignment caused by depletion of endogenous FAM110A. Depletion of FAM110A impaired assembly of F-actin in the proximity of spindle poles and was rescued by expression of the wild-type FAM110A, but not the FAM110A-Δ40-61 mutant. Purified FAM110A promoted binding of F-actin to microtubules as well as bundling of actin filaments in vitro. Finally, we found that the inhibition of CK1 impaired spindle actin formation and delayed progression through mitosis. We propose that CK1 and FAM110A promote timely progression through mitosis by mediating the interaction between spindle microtubules and filamentous actin to ensure proper mitotic spindle formation.
摘要：
有丝分裂过程中染色体的精确分离需要组装双极有丝分裂纺锤体，然后将微管正确连接到动体。这种高度时空组织的过程由各种有丝分裂激酶和分子马达控制。我们最近表明，酪蛋白激酶1（CK1）通过磷酸化FAM110A促进有丝分裂的及时进展，从而导致其在纺锤体两极的富集。然而,FAM110A在有丝分裂中发挥作用的机制尚不清楚。使用结构预测和一组缺失突变体，我们在这里绘制了FAM110A的N端和C端结构域与肌动蛋白和微管蛋白的相互作用，分别。接下来,我们发现，缺乏肌动蛋白结合的FAM110A-Δ40-61突变体未能挽救由内源性FAM110A耗尽引起的染色体排列缺陷。FAM110A的消耗损害了纺锤体极附近的F-肌动蛋白的组装，并通过野生型FAM110A的表达得以挽救，但不是FAM110A-Δ40-61突变体。纯化的FAM110A在体外促进F-肌动蛋白与微管的结合以及肌动蛋白丝的成束。最后,我们发现抑制CK1会损害纺锤体肌动蛋白的形成并延迟有丝分裂的进程。我们建议CK1和FAM110A通过介导纺锤体微管和丝状肌动蛋白之间的相互作用来促进有丝分裂的及时进展，以确保适当的有丝分裂纺锤体形成。
