Functions and modes of action of small G proteins in cell adhesion and migration

小G蛋白在细胞粘附和迁移中的功能和作用方式

基本信息

批准号：
11680632
负责人：
SASAKI Takuya
金额：
$ 2.5万
依托单位：
The University of Tokushima School of Medicine (2000)Osaka University (1999)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

When epithelial cells start to migrate, cell-cell junctions are first disrupted. During migration, membrane protrusions, such as lamellipodia and filopodia, at the cell front, and retraction at the cell rear are externally observed, and dynamic reorganization of the actin cytoskeleton is internally observed. We have recently clarified that the Rho and Rab family small G proteins coordinately regulate cell adhesion and migration of cultured MDCK cells. The Rab family consists of over thirty members. We have found that some Rab family members are involved in HGF- or phorbol esterinduced endocytosis and recycling of cadherin and integrin. Rab11, a member of Rab family, has been implicated in vesicle recycling. During this support from 1999 to 2000, we have focused on studying the function and mode of action of Rab11 in cell migration. The results obtained are as follows :(1) We have isolated a downstream target of Rab11, named Rabphilin-11, from bovine brain. We have found that rabphilin-11 is localized at perinuclear regions, presumably the Golgi complex and recycling endosomes in MDCK cells.(2) We have found that Rabphilin-11 is localized not only at perinuclear regions but also along microtubules, which are oriented toward membrane lammelipodia in HeLa cells cultured on fibronectin. Overexpression of rabphilin-11 mutant reduces accumulation of transferrin at perinuclear regoins and cell migratoin.(3) We have found that rabphilin-11 directly binds the mammalian counterpart of yeast Sec13 proteins (mSec13) in cell-free and intact cell systems. Disruption of the rabphilin-11-mSec13 interaction by overexpression of the mSec13-binding region of rabphilin-11 impairs vesicle trafficking.

当上皮细胞开始迁移时，细胞与细胞的连接首先被破坏。在迁移过程中，从外部观察到细胞前部的膜突出，例如片状伪足和丝状伪足，以及细胞后部的回缩，从内部观察到肌动蛋白细胞骨架的动态重组。我们最近阐明，Rho 和 Rab 家族小 G 蛋白协调调节培养的 MDCK 细胞的细胞粘附和迁移。拉布家族有三十多名成员。我们发现一些 Rab 家族成员参与 HGF 或佛波酯诱导的内吞作用以及钙粘蛋白和整联蛋白的再循环。 Rab11 是 Rab 家族的成员，与囊泡回收有关。在1999年至2000年的支持期间，我们重点研究Rab11在细胞迁移中的功能和作用方式。获得的结果如下：(1)我们从牛脑中分离到了Rab11的下游靶标，命名为Rabphilin-11。我们发现rabphilin-11定位于核周区域，可能是MDCK细胞中的高尔基复合体和循环内体。(2)我们发现Rabphilin-11不仅定位于核周区域，而且还定位于微管，微管朝向在纤连蛋白上培养的 HeLa 细胞中的膜片状伪足。 rabphilin-11突变体的过表达减少了转铁蛋白在核周区域和细胞迁移区的积累。(3)我们发现rabphilin-11在无细胞和完整的细胞系统中直接结合酵母Sec13蛋白的哺乳动物对应物(mSec13)。通过过度表达 rabphilin-11 的 mSec13 结合区来破坏 rabphilin-11-mSec13 相互作用会损害囊泡运输。