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: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=525471
• 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相关蛋白的一个家族，其通常通过调节转运囊泡与靶膜的融合、通过调节这些转运囊泡与细胞骨架的相互作用以及通过调节修饰转运囊泡膜上的脂质的酶来调节膜运输步骤。在人类中有超过60种已知的Rab蛋白，并且已知许多具有特定的细胞器定位并调节特定的转运步骤。我们对在内质网和脂滴上发现的Rab 18特别感兴趣。我们已经发现Rab 18的突变或siRNA敲低导致高尔基体的片段化和分泌途径的损伤（Dejgaard等人，2008.细胞科学杂志，121：2768-81）。在一项单独的ongong研究中，我们发现Rab 18的激活突变体诱导依赖于SNARE蛋白syntaxin-5，SNAP 23和VAMP 4的脂滴的大量融合。 突触融合蛋白-5对于早期分泌途径中的融合事件也是关键的，但其调节尚不清楚。 在当前的申请中，我们提议阐明Rab 18在内质网和高尔基体之间囊泡和货物运动中发挥的重要作用。 我们推测Rab 18在早期分泌途径中部分作为Syntaxin-5的调节剂发挥作用。 我们还探讨了Rab 18在早期分泌途径中调节胆固醇稳态的可能性，并且它可以调节转运中间体上的马达蛋白，该转运中间体在内质网和高尔基体膜之间移动货物。 对于这些研究，我们将使用光学显微镜，siRNA和生物化学技术的组合。