β1 Integrin Cytoplasmic Domain Residues Selectively Modulate Fibronectin Matrix Assembly and Cell Spreading through Talin and Akt-1
β1 Integrin Cytoplasmic Domain Residues Selectively Modulate Fibronectin Matrix Assembly and Cell Spreading through Talin and Akt-1
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DOI：
10.1074/jbc.m805934200
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发表时间：
2009-03-20
影响因子：
4.8
通讯作者：
Yamada, Kenneth M.
中科院分区：
文献类型：
--
作者：
Green, J. Angelo;Berrier, Allison L.;Yamada, Kenneth M.
整合素β（1）胞质结构域（尾）作为许多细胞内蛋白质的支架。尾巴协调这些蛋白质以促进细胞外基质组装和细胞铺展的机制尚不清楚。这项研究表明，β（1）胞质结构域可以通过Akt和talin依赖的机制，分别调节细胞在纤连蛋白和纤连蛋白基质组装上的铺展。为了鉴定这些机制，我们表征了表达β（1）整合素胞质结构域突变体W775 A和R760 A的GD 25细胞。虽然与野生型相比，R760 A突变体整合素细胞中的细胞铺展似乎正常，但在W775 A突变体细胞中，细胞铺展受到抑制。相比之下，两种突变细胞系显示有缺陷的纤连蛋白基质组装。在W775 A突变体细胞中，细胞扩散而非基质组装的抑制是由于Akt-1活化的特定缺陷。此外，我们发现W775 A和R760 A突变体整联蛋白的9 EG 7表位的表面表达减少，这与talin向β（1）整联蛋白胞质复合物的募集减少相关。用小干扰RNA或绿色荧光蛋白-talin头部结构域表达下调talin抑制β 1野生型细胞中的基质组装，模拟W775 A和R760 A突变细胞中观察到的缺陷。这些结果证明了整合素通过β（1）整合素胞质尾调控细胞铺展和基质组装的独特机制。
The integrin beta(1) cytoplasmic domain (tail) serves as a scaffold for numerous intracellular proteins. The mechanisms by which the tail coordinates these proteins to facilitate extracellular matrix assembly and cell spreading are not clear. This study demonstrates that the beta(1) cytoplasmic domain can regulate cell spreading on fibronectin and fibronectin matrix assembly through Akt- and talin-dependent mechanisms, respectively. To identify these mechanisms, we characterized GD25 cells expressing the beta(1) integrin cytoplasmic domain mutants W775A and R760A. Although cell spreading appears normal in R760A mutant-integrin cells compared with wild type, it is inhibited in W775A mutant cells. In contrast, both mutant cell lines show defective fibronectin matrix assembly. Inhibition of cell spreading, but not matrix assembly, in the W775A mutant cells is due to a specific defect in Akt-1 activation. In addition, we find that both W775A and R760A mutant integrins have reduced surface expression of the 9EG7 epitope that correlates with reduced recruitment of talin to beta(1) integrin cytoplasmic complexes. Down-regulation of talin with small interfering RNA or expression of green fluorescent protein-talin head domain inhibits matrix assembly in beta(1) wild-type cells, mimicking the defect seen with the W775A and R760A mutant cells. These results demonstrate distinct mechanisms by which integrins regulate cell spreading and matrix assembly through the beta(1) integrin cytoplasmic tail.