Role of Rab 13 and its effector in establishing cell polarity

Rab 13 及其效应子在建立细胞极性中的作用

基本信息

批准号：
18590271
负责人：
NISHIMURA Noriyuki
金额：
$ 2.51万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18590271/
关键词：
Cell polarity Tight junction Adherens junction Rab13 Rab8 JRAB MICAL-L2 細胞接着オクルーディン

项目摘要

Tight junction (TJ) and adherens junction (AJ) are located at the apical end of the basolateral membrane of polarized epithelial cells. During polarization, epithelial cells first form spot-like primordial AJ at the tips of the initial cell-cell contacts and develop belt-like mature AJ. In parallel with the maturation of AJ, TJ is formed at the apical side of AJ. Whereas epithelial polarization entails a complex interplay between the coordinated TJ and AJ assembly and several fundamental cellular processes, the transport of integral TJ and AJ proteins to and/or from the plasma membrane is essential for the control of TJ and AJ assembly. We previously reported that Rab 13 and a junctional Rab13-binding protein(JRAB)/molecule interacting with CasL-like 2 (MICAL-L2) mediated the endocytic recycling of an integral TJ protein occludin and the formation of functional TJ. In the present study, we examined the role of Rab13 and JRAB/MICAL-L2 in the transport of other integral TJ and AJ proteins claudin-1 and E-cadherin to the plasma membrane. Although knockdown of Rab13 specifically inhibited claudin-1 and occludin but not E-cadherin transport, knockdown of JRAB/MICAL-L2 and expression of its Rab13-binding domain(JRAB/MICAL-L2-C)retarded claudin-1, occludin, and E-cadherin transport. We then identified Rab8 as another JRAB/MICAL-L2-C-binding protein. Knockdown of Rab8 inhibited the Rab13-independent transport of E-cadherin to the plasma membrane. Rab13 and Rab8 competed with each other for the binding to JRAB/MICAL-L2 and functionally associated with JRAB/MICAL-L2 at the plasma membrane and recycling endosome, respectively. These results suggest that the interactions of JRAB/MICAL-L2 with Rab13 and Rab8 play a crucial role in establishing cell polarity.

紧密连接（TJ）和粘附连接（AJ）位于极化上皮细胞基底外侧膜的顶端。在极化过程中，上皮细胞首先在最初的细胞-细胞接触的尖端形成点状原始AJ，并发育成带状成熟AJ。与 AJ 成熟的同时，TJ 在 AJ 的顶端形成。虽然上皮极化需要协调的 TJ 和 AJ 组装以及几个基本细胞过程之间复杂的相互作用，但完整的 TJ 和 AJ 蛋白进出质膜的运输对于 TJ 和 AJ 组装的控制至关重要。我们之前报道过 Rab 13 和与 CasL 样 2 (MICAL-L2) 相互作用的连接 Rab13 结合蛋白 (JRAB)/分子介导了完整 TJ 蛋白 occludin 的内吞再循环和功能性 TJ 的形成。在本研究中，我们研究了 Rab13 和 JRAB/MICAL-L2 在将其他完整 TJ 和 AJ 蛋白claudin-1 和 E-钙粘蛋白转运到质膜中的作用。虽然 Rab13 的敲低特异性抑制了 claudin-1 和 occludin，但不抑制 E-钙粘蛋白转运，但 JRAB/MICAL-L2 的敲低及其 Rab13 结合域 (JRAB/MICAL-L2-C) 的表达会延迟claudin-1、occludin 和 E-cadherin 的转运。 E-钙粘蛋白运输。然后我们将 Rab8 鉴定为另一种 JRAB/MICAL-L2-C 结合蛋白。 Rab8 的敲低抑制了 E-钙粘蛋白不依赖于 Rab13 向质膜的转运。 Rab13 和 Rab8 相互竞争与 JRAB/MICAL-L2 的结合，并分别在质膜和回收内体上与 JRAB/MICAL-L2 功能相关。这些结果表明 JRAB/MICAL-L2 与 Rab13 和 Rab8 的相互作用在建立细胞极性中起着至关重要的作用。