Molecular Regulation of Exocytosis

描述(申请人提供)：胞吐作用是通过运输、对接和融合来自跨高尔基体网络和内小体到质膜的分泌小泡来实现的。由于胞吐作用在从激素释放到胚胎发育的广泛的生理过程中处于中心地位，并且受到严格的控制，因此了解调控胞吐作用的分子机制是很重要的。我们的研究集中在胞吐作用途径中两个独立但又相互联系的“模块”上，即Rab GTP酶和胞囊复合体，这两个模块在进化上从酵母到人类都是保守的。在这个方案中，我们将首先研究控制Rabin8激活的分子机制，Rabin8是Rab8的鸟嘌呤核苷酸交换因子(Genf)，Rab8是哺乳动物细胞胞吐的主要调节因子。我们将研究磷脂酰肌醇和上游Rab蛋白Rab11在Rabin8激活中的作用。此外，我们还将研究细胞外信号调节蛋白1/2(ERK1/2)在响应表皮生长因子(EGF)信号转导过程中对Rabin8蛋白的磷酸化和调节作用。最后，我们将确定外囊在SNARE介导的膜融合中的作用。我们采取了结合生物化学、生物物理学、酵母遗传学和显微成像的多学科方法来解决该领域的关键问题。这些研究不仅有助于我们在分子水平上阐明胞吐作用的调控机制，而且有助于我们了解糖尿病和多囊肾病(PKD)等多种疾病。

DESCRIPTION (provided by applicant): Exocytosis is mediated by transport, docking and fusion of secretory vesicles from trans-Golgi network and endosomes to the plasma membrane. As exocytosis is centrally involved, and tightly controlled, in a wide range of physiological processes from hormone release to embryogenesis, it is important to understand the molecular mechanisms that regulate exocytosis. Our research focuses on two separate but connected "modules" in the exocytosis pathway, the Rab GTPases and the exocyst complex, both of which are evolutionarily conserved from yeast to humans. In this proposal, we wil first investigate the molecular mechanisms that control the activation of Rabin8, which is the guanine nucleotide exchange factor (GEF) for Rab8, a major regulator of exocytosis in mammalian cells. We will examine the role of phosphatidylinositides and an upstream Rab protein, Rab11, in the activation of Rabin8. In addition, we will examine the phosphorylation and regulation of Rabin8 GEF activity by Extracellular signal-regulated kinases 1/2 (ERK1/2) in response epidermal growth factor (EGF) signaling. Finally, we will determine the role of the exocyst in SNARE-mediated membrane fusion. We take a multi-disciplinary approach combining biochemistry, biophysics, yeast genetics and microscopic imaging to address key questions in the field. These studies will not only help us elucidate the regulatry mechanisms of exocytosis at the molecular level, but also contribute to our understanding of a number of diseases such as diabetes and polycystic kidney diseases (PKD).