Roles of Rab18 in ER/golgi trafficking

Rab18 在 ER/高尔基体贩运中的作用

• 批准号: 262040-2011
• 负责人: Presley, John
• 金额: $ 2.91万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=571216
• 关键词: Roles; Rab18; ER; golgi; trafficking

Rabs are a family of Ras-related proteins which typically regulate membrane trafficking steps by regulating fusion of transport vesicles with target membranes, by regulating interaction of these transport vesicles with cytoskeleton and by regulating enzymes that modify lipids on the membrane of transport vesicles. There are more than 60 known Rab proteins in humans and many are known to have a specific organellar localization and to regulate a specific transport step. We have a specific interest in Rab18 which is found on the endoplasmic reticulum and lipid droplets. We have found that mutation or siRNA knockdown of Rab18 causes fragmentation of the Golgi apparatus and impairments in the secretory pathway (Dejgaard et al., 2008. J. Cell Sci., 121:2768-81). In a separate ongong study, we have found that an activated mutant of Rab18 induces profuse fusion of lipid droplets which depends on the SNARE proteins syntaxin-5, SNAP23 and VAMP4. Syntaxin-5 is also critical for fusion events in the early secretory pathway, but its regulation is not well understood. In the current application we propose to clarify the essential roles that Rab18 plays in movement of vesicles and cargo between the endoplasmic reticulum and the Golgi apparatus. We hypothesize that Rab18 is functioning in the early secretory pathway in part as a regulator of Syntaxin-5. We also explore the possibility that Rab18 regulates cholesterol homeostasis in the early secretory pathway and that it could regulate motor proteins on transport intermediates that move cargoes between endoplasmic reticulum and Golgi membranes. For these studies we will use a combination of light microscopy, siRNA and biochemical techniques.

Rabs是ras相关蛋白家族，通常通过调节转运囊泡与靶膜的融合、调节转运囊泡与细胞骨架的相互作用以及调节转运囊泡膜上脂质修饰酶来调节膜运输步骤。已知人类中有60多种Rab蛋白，其中许多已知具有特定的细胞器定位并调节特定的运输步骤。我们对内质网和脂滴上发现的Rab18有特别的兴趣。我们发现Rab18突变或siRNA敲低会导致高尔基体断裂和分泌通路受损（Dejgaard et al., 2008）。J.细胞科学。, 121:2768 - 81)。在另一项正在进行的研究中，我们发现Rab18的激活突变体诱导脂滴的大量融合，这取决于SNARE蛋白syntaxin-5、SNAP23和VAMP4。Syntaxin-5在早期分泌通路的融合事件中也起关键作用，但其调控机制尚不清楚。在目前的应用中，我们建议澄清Rab18在内质网和高尔基体之间的囊泡和货物运动中所起的重要作用。我们假设Rab18在早期分泌途径中部分作为Syntaxin-5的调节剂起作用。我们还探讨了Rab18在早期分泌途径中调节胆固醇稳态的可能性，以及它可以调节在内质网和高尔基膜之间移动货物的运输中间体上的运动蛋白。对于这些研究，我们将使用光学显微镜，siRNA和生化技术的组合。