Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.
Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.
Mol Biol Cell. 2019 Jan 15;30(2):256-267. doi: 10.1091/mbc.E18-05-0279. Epub 2018 Nov 14.
Microtubule biogenesis initiates at various intracellular sites, including the centrosome, the Golgi apparatus, the nuclear envelope, and preexisting microtubules. Similarly, in the fission yeast Schizosaccharomyces pombe, interphase microtubules are nucleated at the spindle pole body (SPB), the nuclear envelope, and preexisting microtubules, depending on Mto1 activity. Despite the essential role of Mto1 in promoting microtubule nucleation, how distribution of Mto1 in different sites is regulated has remained elusive. Here, we show that the J-domain cochaperone Rsp1 interacts with Mto1 and specifies the localization of Mto1 to non-SPB nucleation sites. The absence of Rsp1 abolishes the localization of Mto1 to non-SPB nucleation sites, with concomitant enrichment of Mto1 to the SPB and the nuclear envelope. In contrast, Rsp1 overexpression impairs the localization of Mto1 to all microtubule organization sites. These findings delineate a previously uncharacterized mechanism in which Rsp1-Mto1 interaction orchestrates non-SPB microtubule formation.
微管的生物发生起始于各种细胞内位点，包括中心体、高尔基体、核膜和预先存在的微管。同样，在裂殖酵母 Schizosaccharomyces pombe 中，根据 Mto1 活性，有丝分裂期微管在纺锤体极体 (SPB)、核膜和预先存在的微管处进行核。尽管 Mto1 在促进微管核形成中具有重要作用，但 Mto1 在不同部位的分布如何受到调节仍然难以捉摸。在这里，我们表明 J 结构域共伴侣 Rsp1 与 Mto1 相互作用，并指定 Mto1 到非 SPB 核形成部位的定位。Rsp1 的缺失会消除 Mto1 到非 SPB 核形成部位的定位，同时 Mto1 富集到 SPB 和核膜。相比之下，Rsp1 的过表达会损害 Mto1 到所有微管组织部位的定位。这些发现描绘了一个以前未被表征的机制，其中 Rsp1-Mto1 相互作用协调非 SPB 微管的形成。
