Molecular Mechanisms of Cytokinesis

项目摘要 胞质分裂对细胞增殖、细胞分化和组织动态平衡是必不可少的。大多数活动和 胞质分裂的蛋白质从酵母到人类都是保守的。参与胞质分裂的大多数蛋白质都有 然而，肌球蛋白收缩环收缩、质膜收缩的机制已经确定。 卵裂沟的扩张和细胞外基质的重塑仍然知之甚少；我们也不知道 了解细胞如何协调这些事件以实现成功的细胞分裂。在这里，我们建议继续 以裂殖酵母为模型系统阐明胞质分裂的分子机制。以前的研究 我们可靠的初步数据导致了这一提议的中心假设，即胞吐作用之间的协调 而内吞作用是成功的质膜沉积和隔膜形成的关键。 胞质分裂，而Septins和Ync13是关键的协调者。我们将使用互补的基因， 细胞、显微镜(共聚焦、TIRFM、电子显微镜、电子断层扫描和超分辨率)， 生物化学、结构和计算方法通过调查三个具体目标来验证这一假设： 1)阐明间隔素如何定义外囊束缚小泡的位置，以及它们如何影响 内吞作用；2)描述YNC13在胞质分裂过程中如何协调胞吐和内吞作用；3) 研究葡聚糖合成酶的运输、锚定和调节的分子机制 胞质分裂。我们对Septins、外囊、Munc13/UNC-13蛋白Ync13、F-13之间关系的研究 BAR蛋白RGa7、卷曲蛋白RNG10和葡聚糖合成酶将在主要的 胞质分裂事件。我们提出的研究具有重要意义，因为它们将促进对 胞质分裂有三个重要途径：a)在胞吐和胞内作用中，隔膜蛋白的作用是什么？ 胞质分裂；b)Ync13如何协调胞吐和胞吞作用以实现成功的胞质分裂；c)隔膜如何 合酶是被交易和监管的。从这个项目中学到的概念将适用于理解 间隔素、胞外囊、质膜沉积和细胞外基质重塑的协调 因为我们的三个特定目标涉及细胞质分裂最保守的方面。因为 真菌特有的基本酶，如葡聚糖合成酶，在细胞质分裂期间形成隔膜，是 作为几种抗真菌药物的靶标，我们对这些合酶的调节机制的研究可能会导致新的 抗真菌药物的靶标。因此，我们在细胞质分裂的保守和真菌特异性方面的发现 可能被利用来改善人类健康。

Project Summary Cytokinesis is essential for cell proliferation, cell differentiation, and tissue homeostasis. Most events and proteins of cytokinesis are conserved from yeast to humans. Majority of the proteins involved in cytokinesis have been identified, however, the mechanisms of actomyosin contractile-ring constriction, plasma-membrane expansion in the cleavage furrow, and extracellular matrix remodeling are still poorly understood; nor do we understand how cells coordinate these events for successful cell division. Here we propose to continue elucidating the molecular mechanisms of cytokinesis using fission yeast as a model system. Previous studies and our solid preliminary data led to the central hypothesis of this proposal that coordination between exocytosis and endocytosis is essential for successful plasma membrane deposition and septum formation during cytokinesis, and septins and Ync13 are among the crucial coordinators. We will use complementary genetic, cellular, microscopic (confocal, TIRFM, electron microscopy, electron tomography, and super-resolution), biochemical, structural, and computational approaches to test this hypothesis by investigating three specific aims: 1) Elucidate how septins define the sites of vesicle tethering by the exocyst and how they affect the sites of endocytosis; 2) Characterize how Ync13 coordinates exocytosis and endocytosis during cytokinesis; 3) Investigate molecular mechanisms of trafficking, anchoring, and regulation of glucan synthases during cytokinesis. Our studies on the relationships between septins, the exocyst, Munc13/UNC-13 protein Ync13, F- BAR protein Rga7, coiled-coil protein Rng10, and glucan synthases will provide molecular links among the main cytokinesis events. Our proposed studies are significant because they will advance the understanding of cytokinesis in three important ways: a) What are the roles of septins in exocytosis and endocytosis during cytokinesis; b) how Ync13 coordinates exocytosis and endocytosis for successful cytokinesis; c) how septum synthases are trafficked and regulated. The concepts learned from this project will be applicable to understand the coordination of septins, the exocyst, plasma-membrane deposition, and extracellular matrix remodeling in human cells because our three specific aims involve the most conserved aspects of cytokinesis. Because the fungal specific essential enzymes such as glucan synthases, which build the septum during cytokinesis, are targets of several antifungals, our studies on the regulators of these synthases proposed here may lead to novel targets for antifungal drugs. Thus, our discoveries on both conserved and fungal-specific aspects of cytokinesis may be harnessed to improve human health.