VTC Events Mediated by the Rab2 Complex

描述(由申请人提供)：我们的长期目标是了解从泡状管状簇(VTC)中分离和回收蛋白质的机制。VTC充当运输综合体，将货物从ER运送到高尔基综合体。此外，这些结构是顺行和逆行通路的第一个分离部位，因此发挥着关键功能。小的GTP酶Rab2在这一转运步骤中起着至关重要的作用，它促进逆行导向的囊泡的形成，这些囊泡将回收的货物带回内质网。Rab2介导的囊泡形成需要非典型的PKCi/X和GAPDH。在本申请中，我们建议从机械上表征Rab2，并确定Rab2在与VTC相关的事件中的作用。其具体目的是：1)鉴定与Rab2结合的VTC亚室的蛋白质组分；2)通过绘制Rab2复合体的相互结合结构域来表征Rab2复合体各组分之间的相互作用；3)阐明VTC依赖Rab2的逆行囊泡萌发的分子机制。研究Rab2在分泌物中的功能的重要性通过观察到Rab2、PKC和GAPDH的高表达与各种癌症的高转移潜能相关。由于转移是细胞骨架重组和细胞运动增加的反映，值得注意的是，Rab2及其效应器影响微管动力学。然而，Rab2、aPKCi/A和GAPDH在早期分泌途径中的确切功能以及这些蛋白在疾病中的作用尚不清楚。本申请中提出的研究将开发一种新的、新的范式，将Rab2-aPKC la-GAPDH功能障碍与病理后果结合起来。

DESCRIPTION (provided by applicant): Our long-term goal is to understand the mechanism of protein sorting and recycling from vesicular tubular clusters (VTCs). VTCs function as transport complexes delivering cargo from the ER to the Golgi complex. Moreover, these structures are the first site of segregation of the anterograde and retrograde pathways and thereby perform a critical function. The small GTPase Rab2 plays an essential role in this trafficking step by promoting formation of retrograde-directed vesicles that carry recycling cargo back to the ER. Rab2- mediated vesicle formation requires atypical PKCi/X and GAPDH. In this application we propose to characterize Rab2 mechanistically and to establish the role of Rab2 in events associated with VTCs. The Specific Aims are: 1) to identify the protein components of the VTC subcompartment that binds Rab2, 2) to characterize the interaction between components of the Rab2 complex by mapping their reciprocal binding domains, and 3) elucidate the molecular mechanism of Rab2-dependent-retrograde vesicle budding from VTCs. The importance of investigating Rab2 function in secretion is underscored by the observation that elevated Rab2, PKC, and GAPDH expression correlates with high metastatic potential in various cancers. Since metastasis is a reflection of cytoskeletal reorganization and increased cell motility, it is noteworthy that Rab2 and its effectors influence microtubule dynamics. However, the precise function of Rab2, aPKCi/A, and GAPDH in the early secretory pathway and how these proteins contribute to the disease are unknown. The studies proposed in this application will develop a new and novel paradigm that couples Rab2-Apkc lA-GAPDH dysfunction with pathological consequences.