Regulation of the mitogen-activated protein kinase signaling pathway by SHP2
Regulation of the mitogen-activated protein kinase signaling pathway by SHP2
复制标题
DOI：
10.1074/jbc.m110547200
复制
发表时间：
2002-03-15
影响因子：
4.8
通讯作者：
Wu, J
中科院分区：
文献类型：
--
作者：
Cunnick, JM;Meng, SS;Wu, J
Gab 1-SHP 2的结合是Erk丝裂原活化蛋白激酶被几种生长因子激活所必需的。Gab 1-SHP 2相互作用激活SHP 2。然而，激活的SHP 2仍然需要与Gab 1结合以介导Erk激活。尚不清楚SHP 2是否需要去磷酸化Gab 1上的负磷酸化位点，或者SHP 2是否需要Gab 1普列克底物蛋白同源（PH）结构域将其靶向质膜。我们发现由Gab 1 PH结构域和活性SHP 2（Gab 1 PH-SHP 2DeltaN）组成的融合蛋白的表达诱导组成型Mek 1和Erk 2活化。将活性SHP 2DeltaN与PDK 1 PH结构域或FRS 2 β豆蔻酰化序列连接也诱导Mek 1活化。Mek 1激活Gab 1 PH-SHP 2DeltaN抑制Src抑制剂和Csk。Gab 1 PH-SHP 2DeltaN显著诱导Src活化。Gab 1 PH-SHP 2DeltaN的表达激活Ras，而Gab 1 PH-SHP 2DeltaN诱导的Mek 1激活被RasN 17阻断。这些发现表明它在Gab 1 PH-SHP 2DeltaN激活Src和Ras上游的信号步骤。SHP 2酪氨酸磷酸酶活性对于融合蛋白的功能是必不可少的。总之，这些数据表明，Gab 1序列，除了PH结构域和SHP 2结合位点，是Erk激活，这表明Gab 1与激活的SHP 2的主要作用是将其靶向膜。
Gab1-SHP2 association is required for Erk mitogen-activated protein kinase activation by several growth factors. Gab1-SHP2 interaction activates SHP2. However, an activated SHP2 still needs to associate with Gab1 to mediate Erk activation. It was unclear whether SHP2 is required to dephosphorylate a negative phosphorylation site on Gab1 or whether SHP2 needs the Gab1 pleckstrin homology (PH) domain to target it to the plasma membrane. We found that expression of a fusion protein consisting of the Gab1 PH domain and an active SHP2 (Gab1PH-SHP2DeltaN) induced constitutive Mek1 and Erk2 activation. Linking the active SHP2DeltaN to the PDK1 PH domain or the FRS2beta myristoylation sequence also induced Mek1 activation. Mek1 activation by Gab1PH-SHP2DeltaN was inhibited by an Src inhibitor and by Csk. Significantly, Gab1PH-SHP2DeltaN induced Src activation. Gab1PH-SHP2DeltaN expression activated Ras, and the Gab1PH-SHP2DeltaN-induced Mek1 activation was blocked by RasN17. These findings suggest It at Gab1PH-SHP2DeltaN activated a signaling step upstream of Src and Ras. The SHP2 tyrosine phosphatase activity is essential for the function of the fusion protein. Together, these data show that the Gab1 sequence, besides the PH domain and SHP2 binding sites, is dispensable for Erk activation, suggesting that the primary role of Gab1 association with an activated SHP2 is to target it to the membrane.