Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
Genetics. 2019 Jun;212(2):509-522. doi: 10.1534/genetics.119.302105. Epub 2019 Apr 24.
During mitosis, kinetochore-microtubule interactions ensure that chromosomes are accurately segregated to daughter cells. RSA-1 (regulator of spindle assembly-1) is a regulatory B″ subunit of protein phosphatase 2A that was previously proposed to modulate microtubule dynamics during spindle assembly. We have identified a genetic interaction between the centrosomal protein, RSA-1, and the spindle- and kinetochore-associated (Ska) complex in In a forward genetic screen for suppressors of embryonic lethality, we identified mutations in and Loss of SKA-1 and SKA-3, as well as components of the KMN (KNL-1/MIS-12/NDC-80) complex and the microtubule end-binding protein EBP-2, all suppressed the embryonic lethality of These suppressors also disrupted the intracellular localization of the Ska complex, revealing a network of proteins that influence Ska function during mitosis. In embryos, SKA-1 is excessively and prematurely recruited to kinetochores during spindle assembly, but SKA-1 levels return to normal just prior to anaphase onset. Loss of the TPX2 homolog, TPXL-1, also resulted in overrecruitment of SKA-1 to the kinetochores and this correlated with the loss of Aurora A kinase on the spindle microtubules. We propose that regulates the kinetochore localization of the Ska complex, with spindle-associated Aurora A acting as a potential mediator. These data reveal a novel mechanism of protein phosphatase 2A function during mitosis involving a centrosome-based regulatory mechanism for Ska complex recruitment to the kinetochore.
在有丝分裂过程中，动粒微管相互作用确保染色体准确地分配到子细胞中。RSA-1（纺锤体组装调节因子-1）是蛋白磷酸酶 2A 的调节 B″亚基，先前被提议调节纺锤体组装过程中的微管动力学。我们已经确定了中心体蛋白 RSA-1 与纺锤体和动粒相关（Ska）复合物之间的遗传相互作用，在胚胎致死性的正向遗传筛选中，我们在 和 中发现了突变。SKA-1 和 SKA-3 的缺失，以及 KMN（KNL-1/MIS-12/NDC-80）复合物和微管末端结合蛋白 EBP-2 的成分，都抑制了 的胚胎致死性。这些抑制剂也破坏了 Ska 复合物的细胞内定位，揭示了影响 Ska 在有丝分裂过程中功能的蛋白质网络。在 胚胎中，SKA-1 在纺锤体组装过程中过早地被过度募集到动粒上，但在后期开始之前，SKA-1 水平恢复正常。TPX2 同源物 TPXL-1 的缺失也导致 SKA-1 过度募集到动粒上，这与纺锤体微管上 Aurora A 激酶的丢失相关。我们提出， 调节 Ska 复合物在动粒上的定位，纺锤体相关的 Aurora A 作为潜在的介导物起作用。这些数据揭示了蛋白磷酸酶 2A 在有丝分裂过程中功能的一种新机制，涉及到中心体为基础的 Ska 复合物募集到动粒的调节机制。
