Inhibition of cell spreading by expression of the C-terminal domain of focal adhesion kinase (FAK) is rescued by coexpression of Src or catalytically inactive FAK: A role for paxillin tyrosine phosphorylation
Inhibition of cell spreading by expression of the C-terminal domain of focal adhesion kinase (FAK) is rescued by coexpression of Src or catalytically inactive FAK: A role for paxillin tyrosine phosphorylation
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DOI：
10.1128/mcb.17.12.6906
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发表时间：
1997-12-01
影响因子：
5.3
通讯作者：
Parsons, JT
中科院分区：
文献类型：
--
作者：
Richardson, A;Malik, RK;Parsons, JT
pp 125（FAK）是酪氨酸激酶，其似乎调节粘着斑的组装，从而促进细胞在细胞外基质上的铺展。在一些细胞中，pp 125（FAK）的C末端表达为单独的蛋白质pp 41/43（FRNK）。我们以前已经表明，pp 41/43（FRNK）的过表达抑制pp 125（FAK）和桩蛋白的酪氨酸磷酸化，此外，延迟细胞铺展和粘着斑组装。因此，pp 41/43（FRNK）作为粘附信号传导的负抑制剂起作用，并提供了一种工具来剖析pp 125（FAK）促进细胞铺展的机制。我们在这里报告，pp 41/43（FRNK）表达的抑制作用可以通过野生型pp 125（FAK）的共过表达和pp 125（FAK）的无催化活性变体部分拯救。然而，pp 125的自磷酸化位点突变体（FAK）（其不能结合pp 60的SH 2结构域（c-Src））或不能结合桩蛋白的突变体的共表达不促进细胞铺展。相反，pp 41/43（FRNK）和pp 60（c-Src）的表达重建了细胞铺展和桩蛋白的酪氨酸磷酸化，但没有诱导pp 125（FAK）的酪氨酸磷酸化。这些数据为pp 125（FAK）作为“可转换的适配器”的模型提供了额外的支持，该模型招募pp 60（c-Src）使桩蛋白磷酸化，促进细胞扩散。此外，这些数据表明桩蛋白的酪氨酸磷酸化是粘着斑组装的关键步骤。
pp125(FAK) is tyrosine kinase that appears to regulate the assembly of focal adhesions and thereby promotes cell spreading on the extracellular matrix. In some cells, the C terminus of pp125(FAK) is expressed as a separate protein, pp41/43(FRNK). We have previously shown that overexpression of pp41/43(FRNK) inhibits tyrosine phosphorylation of pp125(FAK) and paxillin and, in addition, delays cell spreading and focal adhesion assembly. Thus, pp41/43(FRNK) functions as a negative inhibitor of adhesion signaling and provides a tool to dissect the mechanism by which pp125(FAK) promotes cell spreading. We report here that the inhibitory effects of pp41/43(FRNK) expression can be rescued by the co-overexpression of wild-type pp125(FAK) and partially rescued by catalytically inactive variants of pp125(FAK). However, coexpression of an autophosphorylation site mutant of pp125(FAK), Which fails to bind the SH2 domain of pp60(c-Src), or a mutant that fails to bind paxillin did not promote cell spreading. In contrast, expression of pp41/43(FRNK) and pp60(c-Src) reconstituted cell spreading and tyrosine phosphorylation of paxillin but did so without inducing tyrosine phosphorylation of pp125(FAK). These data provide additional support for a model whereby pp125(FAK) acts as a ''switchable adaptor'' that recruits pp60(c-Src) to phosphorylate paxillin, promoting cell spreading. In addition, these data point to tyrosine phosphorylation of paxillin as being a critical step in focal adhesion assembly.