Vang-like protein 2 and Rac1 interact to regulate adherens junctions
Vang-like protein 2 and Rac1 interact to regulate adherens junctions
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DOI：
10.1242/jcs.048074
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发表时间：
2010-02-01
影响因子：
4
通讯作者：
Ringstedt, Thomas
中科院分区：
文献类型：
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作者：
Lindqvist, Maria;Horn, Zachi;Ringstedt, Thomas
Wnt平面细胞极性(Wnt/PCP)通路通过小的Rho样GTP酶来调节细胞骨架。PCP核心蛋白在基因上定位于Wnt/PCP途径，但其作用的分子机制尚不清楚。在这里，我们研究哺乳动物PCP蛋白Vang-like Protein 2(Vangl2)的功能。Vangl2的RNAi敲除会损害HEK293T和MDCK上皮细胞的细胞间黏附和细胞骨架的完整性。当Vangl2在HEK293T、MDCK或C17.2细胞中过表达时，也观察到类似的效应。Vangl2过表达的影响可以通过敲除小的GTP酶rac1或被显性负值的rac1所阻断。就其本身而言，Rac1基因的敲除损害了细胞骨架的完整性，降低了细胞与细胞之间的黏附。我们发现，Vangl2结合并重新分布了细胞内的rac1，但不改变rac1的活性。此外，在神经干细胞中过度表达Vangl2的转基因小鼠胚胎和环尾Vangl2功能丧失的胚胎都显示出粘连连接受损，粘连连接是神经管僵硬和神经管关闭所必需的细胞骨架单位。在体内，rac1以类似于我们在体外观察到的方式在细胞内重新分布。我们认为，Vangl2通过招募rac1并将其在细胞内的活性靶向于黏附连接来影响细胞黏附和细胞骨架。
The Wnt planar cell polarity (Wnt/PCP) pathway signals through small Rho-like GTPases to regulate the cytoskeleton. The core PCP proteins have been mapped to the Wnt/PCP pathway genetically, but the molecular mechanism of their action remains unknown. Here, we investigate the function of the mammalian PCP protein Vang-like protein 2 (Vangl2). RNAi knockdown of Vangl2 impaired cell-cell adhesion and cytoskeletal integrity in the epithelial cell lines HEK293T and MDCK. Similar effects were observed when Vangl2 was overexpressed in HEK293T, MDCK or C17.2 cells. The effects of Vangl2 overexpression could be blocked by knockdown of the small GTPase Rac1 or by dominant-negative Rac1. In itself, knockdown of Rac1 impaired cytoskeletal integrity and reduced cell-cell adhesion. We found that Vangl2 bound and re-distributed Rac1 within the cells but did not alter Rac1 activity. Moreover, both transgenic mouse embryos overexpressing Vangl2 in neural stem cells and loop-tail Vangl2 loss-of-function embryos displayed impaired adherens junctions, a cytoskeletal unit essential for neural tube rigidity and neural tube closure. In vivo, Rac1 was re-distributed within the cells in a similar way to that observed by us in vitro. We propose that Vangl2 affects cell adhesion and the cytoskeleton by recruiting Rac1 and targeting its activity in the cell to adherens junctions.