Interaction between Src and a C-terminal proline-rich motif of Akt is required for Akt activation
Interaction between Src and a C-terminal proline-rich motif of Akt is required for Akt activation
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DOI：
10.1074/jbc.m212525200
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发表时间：
2003-05-02
影响因子：
4.8
通讯作者：
Qiu, Y
中科院分区：
文献类型：
--
作者：
Jiang, TY;Qiu, Y
Akt被生长因子激活是一个多步骤的过程。在这里，我们提供的证据表明，酪氨酸激酶Src通过其SH3结构域与Akt的C末端调节区中一个保守的富含脯氨酸的基序(PXXP)之间的相互作用而与Akt直接相关。Pro-424和Pro-427的Pro-424和Pro-427被丙氨酸取代导致Akt活性丧失和由表皮生长因子(EGF)诱导的磷酸化，可能是因为这些突变破坏了Akt和Src的SH3结构域之间的相互作用。我们的观察证实了这种可能性，即缺乏这两个Pro的Akt突变体在体内和体外都不能与Src结合。我们还表明，由Src或EGF诱导的Akt中Tyr-315的磷酸化依赖于这个富含Pro的基序的完整性。此外，缺失这个Pro基序的Akt突变体不能阻断293细胞中Forkhead的转录活性，并且不能刺激Madin-Darby犬肾细胞的增殖。综上所述，我们的数据表明，Src家族激酶的SH3结构域与Akt的C末端调控区富含Pro的基序之间的相互作用是Akt酪氨酸磷酸化及其随后激活所必需的。值得注意的是，这个PXXP基序在AGC激酶家族的几个成员中都是保守的，这意味着这个基序与上游调控因子的SH3结构域的结合可能也代表了适用于这些激酶的一般机制。
Activation of Akt by growth factors is a multistep process. Here, we provide evidence that tyrosine kinase Src is directly associated with Akt through the interaction between its SH3 domain and a conserved proline-rich motif (PXXP) in the C-terminal regulatory region of Akt. Substitution of the proline residues Pro-424 and Pro-427 by alanines results in loss of Akt activity and phosphorylation induced by the epidermal growth factor (EGF), possibly because these mutations disrupt the interaction between Akt and the SH3 domain of Src. This possibility is corroborated by our observation that the Akt mutant lacking these two prolines fails to bind to Src both in vivo and in vitro. We also showed that phosphorylation of Tyr-315 in Akt induced by Src or EGF is dependent on the integrity of this proline-rich motif. Furthermore, the Akt mutant lacking this proline motif fails to block the transcription activity of Forkhead in 293 cells and poorly stimulates the proliferation of Madin-Darby canine kidney cells. Taken together, our data suggest that the interaction between the SH3 domain of Src family kinases and the proline-rich motif in the C-terminal regulatory region of Akt is required for tyrosine phosphorylation of Akt and its subsequent activation. It is noteworthy that this PXXP motif is conserved throughout several members of AGC kinase family, implying that association of this motif with the SH3 domain of an upstream regulator may represent a general mechanism applicable to these kinases as well.