Preferential phosphorylation of focal adhesion kinase tyrosine 861 is critical for mediating an anti-apoptotic response to hyperosmotic stress
Preferential phosphorylation of focal adhesion kinase tyrosine 861 is critical for mediating an anti-apoptotic response to hyperosmotic stress
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DOI：
10.1074/jbc.m607780200
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发表时间：
2007-04-06
影响因子：
4.8
通讯作者：
Rozengurt, Enrique
中科院分区：
文献类型：
--
作者：
Lunn, J. Adrian;Jacamo, Rodrigo;Rozengurt, Enrique
本研究的结果表明，在多种细胞类型中，局灶黏附激酶（FAK） Tyr-861是高渗应激刺激下的主要酪氨酸磷酸化位点，包括上皮细胞系（回肠来源的IEC-18、结肠来源的cca02和胃来源的NCI-N87）、FAK缺失的再表达FAK的成纤维细胞和Src家族激酶三缺失的成纤维细胞（SYF细胞），其中c-Src已经恢复（YF细胞）。我们发现上皮细胞中高渗应激刺激的FAK磷酸化被Src家族激酶抑制剂PP2和SU6656抑制，而在SYF细胞中不发生。出乎意料的是，高渗应激诱导的FAK在tyr397、tyr576和tyr861位点的磷酸化对f -肌动蛋白破坏剂latrunculin A和细胞松弛素d完全不敏感。最后，我们发现，在暴露于高渗应激或生长因子停用的FAK零细胞中，野生型FAK的重新表达恢复了细胞存活，而在861位点（FAKY861F）从酪氨酸突变为苯丙氨酸的FAK的重新表达则没有恢复细胞存活。我们的研究结果表明FAK Tyr- 861磷酸化是高渗应激下哺乳动物细胞存活所必需的。此外，结果表明FAK是高渗胁迫下f -肌动蛋白重组的上游调节因子（而不是下游效应因子）。我们提出FAK/c-Src双部酶是细胞质收缩的传感器，并且Src对FAK tir -861的磷酸化和随后的f -肌动蛋白重组可以启动一个抗凋亡信号通路，保护细胞免受高渗应激。
The results presented here demonstrate that focal adhesion kinase ( FAK) Tyr-861 is the predominant tyrosine phosphorylation site stimulated by hyperosmotic stress in a variety of cell types, including epithelial cell lines (ileum-derived IEC-18, colon-derived Caco2, and stomach-derived NCI-N87), FAK null fibroblasts re-expressing FAK, and Src family kinase triple null fibroblasts ( SYF cells) in which c-Src has been restored ( YF cells). We show that hyperosmotic stress-stimulated FAK phosphorylation in epithelial cells is inhibited by Src family kinase inhibitors PP2 and SU6656 and that it does not occur in SYF cells. Unexpectedly, hyperosmotic stress-induced phosphorylation of FAK at Tyr-397, Tyr-576, and most dramatically at Tyr-861 was completely insensitive to the F-actin-disrupting agents, latrunculin A and cytochalasin D. Finally, we show that in FAK null cells exposed to hyperosmotic stress or growth factor withdrawal, re-expression of wild type FAK restored cell survival, whereas re-expression of FAK mutated from tyrosine to phenylalanine at position 861 (FAKY861F) did not. Our results indicate that FAK Tyr- 861 phosphorylation is required for mammalian cell survival of hyperosmotic stress. Furthermore, the results suggest that FAK is an upstream regulator ( rather than downstream effector) of F-actin reorganization in response to hyperosmotic stress. We propose that FAK/c-Src bipartite enzyme is a sensor of cytoplasmic shrinkage, and that the phosphorylation on FAK Tyr-861 by Src and subsequent reorganization of F-actin can initiate an anti- apoptotic signaling pathway that protects cells from hyperosmotic stress.