Mechanisms of chromosome segregation and mitotic timing

 描述(申请人提供)：这项建议旨在研究动粒蛋白捕获微管的机制，以确保通过有丝分裂实现平等的染色体分离和及时的进展。通过对纺锤体相关的层蛋白-B网络(我们以前称之为纺锤体基质)的分析，我们得到了许多令人兴奋的观察结果，表明层蛋白-B网络的组成部分(S)与微管一起作为动粒蛋白如Bub3的伴侣。动粒蛋白需要这些伴侣来调节适当的微管和动粒的相互作用以及适时的有丝分裂进程。我们建议剖析这些伴侣在有丝分裂中发挥作用的分子机制。具体地说，在目标1中，我们将剖析BuGZ与微管和/或EB1之间的相互作用是否以及如何才是Bub3动粒加载和染色体比对所必需的。在目标2中，我们将研究RanGTP对BuGZ和Bub3的失稳是否有助于纺锤体组装检查点(SAC)的沉默。在目标3中，我们建议研究介导末端动粒-MT连接和SAC沉默的分子机制。

 DESCRIPTION (provided by applicant): This proposal aims to study the mechanism by which kinetochore proteins capture microtubules to ensure equal chromosome segregation and timely progression through mitosis. Through analyzing the spindle-associated lamin-B containing network, which we had referred to as the spindle matrix previously, we have made a number of exciting observations, which suggest that component(s) of the lamin-B network functions together with microtubules as chaperones for kinetochore proteins such as Bub3. These chaperones are required for kinetochore proteins to regulate proper microtubule and kinetochore interactions and timely mitosis progression. We propose to dissect the molecular mechanism by which these chaperones function in mitosis. Specifically, in Aim 1 we will dissect whether and how the interaction between BuGZ and microtubules and/or EB1 is required for Bub3 kinetochore loading and chromosome alignment. In Aim 2 we will study whether the destabilization of BuGZ and Bub3 by RanGTP contributes to silencing of the spindle assembly checkpoint (SAC). In Aim 3, we propose to study the molecular mechanisms that mediate end-on kinetochore-MT attachment and SAC silencing.