Chen H C, Appeddu P A, Isoda H, Guan J L
Cancer Biology Laboratories, Department of Pathology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
J Biol Chem. 1996 Oct 18;271(42):26329-34. doi: 10.1074/jbc.271.42.26329.
We have shown previously that cell adhesion or platelet-derived growth factor (PDGF) promotes the in vivo association of focal adhesion kinase (FAK) with phosphatidylinositol (PI) 3-kinase. In vitro experiments indicated that this interaction was mediated by the p85 subunit of PI 3-kinase and dependent on the tyrosine phosphorylation of FAK. Here we report data suggesting that the major autophosphorylation site of FAK (Tyr-397) is the binding site for the SH2 domains of p85 in vitro and is also required for the association of FAK with PI 3-kinase in vivo. We also show that Tyr-397 is responsible for the increased FAK:PI 3-kinase association upon PDGF stimulation, implying that no additional site of FAK was involved in its binding to PI 3-kinase after PDGF stimulation. Finally, we present evidence that the interaction of PI 3-kinase with Tyr-397 of FAK stimulates its activity. Together, these results suggest that FAK activation and autophosphorylation at Tyr-397 may lead to its association with PI 3-kinase through the SH2 domains of p85, which can subsequently activate PI 3-kinase during cell adhesion.
我们之前已经表明，细胞黏附或血小板衍生生长因子（PDGF）可促进黏着斑激酶（FAK）在体内与磷脂酰肌醇（PI）3激酶的结合。体外实验表明，这种相互作用是由PI 3激酶的p85亚基介导的，并且依赖于FAK的酪氨酸磷酸化。在此我们报告的数据表明，FAK的主要自磷酸化位点（Tyr-397）在体外是p85的SH2结构域的结合位点，并且在体内也是FAK与PI 3激酶结合所必需的。我们还表明，Tyr-397负责PDGF刺激后FAK与PI 3激酶结合的增加，这意味着PDGF刺激后FAK与PI 3激酶结合没有涉及其他额外的位点。最后，我们提供证据表明PI 3激酶与FAK的Tyr-397相互作用会刺激其活性。总之，这些结果表明，FAK在Tyr-397处的激活和自磷酸化可能通过p85的SH2结构域导致其与PI 3激酶结合，这随后可在细胞黏附过程中激活PI 3激酶。
