Centrosome Protein Function

中心体以其组织微管形成间期阵列和有丝分裂纺锤体的能力而闻名。最近的研究表明，中心体参与胞质分裂和细胞周期进程。 然而，很少有人知道的中心体蛋白，有助于这些过程。在上一个资助期，我们研究了这些未充分探索的中心体功能的分子基础。我们发现了一种新的中心体蛋白，称为centriolin，这是必不可少的哺乳动物细胞的胞质分裂。 Centriolin与涉及或参与胞质分裂的蛋白质相互作用，包括snapin（SNARE）、sec 15（外囊）、MKLP-1（centralspindlin）和Rho GTP酶的新型GTP酶激活蛋白。其中许多蛋白质定位于分裂细胞的中体，并在下调时诱导胞质分裂缺陷。基于这些和其他数据，我们提出了一个模型，其中中心蛋白作为支架蛋白在中间体，以协调囊泡融合，微管解聚，沟侵入和细胞分裂后期的细胞分离。由中心蛋白下调诱导的有缺陷的胞质分裂随后发生G1期阻滞。我们出乎意料地发现，许多中心体蛋白诱导胃肠道停滞时，下调。然而，这种停滞与胞质分裂或其他中心体功能或中心体结构的缺陷无关 或组成。我们假设，细胞周期阻滞是由一个检查点触发的，该检查点监测尚未确定的共同功能中的缺陷，或由中心体中单个蛋白质的减少引起的“中心体损伤”。胃肠道阻滞需要p53和p38 MAP激酶，并诱导激活的p53和p38募集到中心体。根据这些观察，我们提出了两个具体目标。在目的1中，我们将确定中心素和相关蛋白质在胞质分裂中的作用。更具体地说，我们将测试中心蛋白是否锚定这些蛋白质在中间体，如果这些蛋白质的复合物控制囊泡融合，微管 组织和细胞分离在中间体。目的2：研究中心体蛋白在细胞周期进程和检查点激活中的作用。我们将确定GI停滞的机制，并确定连接中心体蛋白和细胞周期停滞的信号转导通路。

Centrosomes are best known for their ability to organize microtubules to form interphase arrays and mitotic spindles. Recent evidence suggests that centrosomes are involved hi cytokinesis and cell cycle progression. However, little is known about the centrosome proteins that contribute to these processes. In the previous funding period, we examined the molecular basis for these under-explored centrosome functions. We identified a novel centrosome protein called centriolin, which is essential for cytokinesis in mammalian cells. Centriolin interacts with proteins implicated or involved in cytokinesis including snapin (SNARE), sec 15 (exocyst), MKLP-1 (centralspindlin) and a novel GTPase activating protein for Rho GTPases. Many of these proteins localize to the midbody in dividing cells and induce cytokinesis defects when downregulated. Based on these and other data, we propose a model in which centriolin serves as a scaffold protein at the midbody to coordinate vesicle fusion, microtubule depolymerization, furrow ingression and cell separation late in cytokinesis. Defective cytokinesis induced by centriolin downregulation was followed by Gl arrest. We unexpectedly found that many centrosome proteins induced GI arrest when downregulated. However, the arrest did not correlate with defects in cytokinesis or other centrosome functions, or in centrosome structure or composition. We postulate that cell cycle arrest is triggered by a checkpoint that monitors defects in a common function not yet identified, or 'centrosome damage' induced by reduction of individual proteins at centrosomes. GI arrest requires p53 and p38 MAP kinase and induces recruitment of activated p53 and p38 to centrosomes. Based on these observations, we propose two specific aims. In Aim 1 we will determine the role centriolin and associated proteins hi cytokinesis. More specifically, we will test whether centriolin anchors these proteins at the midbody and if a complex of these proteins controls vesicle fusion, microtubule organization and cell separation at the midbody. Aim 2 focuses on the role of centrosome proteins in cell cycle progression and checkpoint activation. We will determine the mechanism of GI arrest and identify the signal transduction pathway that connects centrosome proteins to cell cycle arrest.