Protein kinase Cδ induces Src kinase activity via activation of the protein tyrosine phosphatase PTPα
Protein kinase Cδ induces Src kinase activity via activation of the protein tyrosine phosphatase PTPα
复制标题
DOI：
10.1074/jbc.m211650200
复制
发表时间：
2003-09-05
影响因子：
4.8
通讯作者：
Mischak, H
中科院分区：
文献类型：
--
作者：
Brandt, DT;Goerke, A;Mischak, H
先前我们已经表明，蛋白激酶C（PKC）介导的平滑肌细胞中肌动蛋白细胞骨架的重组是由非受体酪氨酸激酶Src传递的。一些作者已经描述了12 - O - 十四酰佛波醇 - 13 - 乙酸酯（TPA）对细胞的刺激如何导致Src活性增加，但PKC介导的Src激活机制尚不清楚。利用从草地贪夜蛾昆虫细胞中纯化的PKC同工酶，我们在此表明PKC不能直接激活Src。我们的数据显示，PKC依赖的Src激活是通过蛋白酪氨酸磷酸酶（PTP）PTPα的激活而发生的。在TPA刺激后，PTPα在体内被激活。此外，我们表明PKCδ在体外仅磷酸化并激活PTPα，而不激活在A7r5大鼠主动脉平滑肌细胞中表达的任何其他对TPA有反应的PKC同工酶。为了进一步证实我们的数据，我们表明缺乏PKCδ的细胞在12 - O - 十四酰佛波醇 - 13 - 乙酸酯刺激后，PTPα和Src活性显著降低。这些数据支持这样一种模型：12 - O - 十四酰佛波醇 - 13 - 乙酸酯诱导的Src激活的主要机制是PKCδ对PTPα的直接磷酸化和激活，而PTPα反过来使Src去磷酸化并激活Src。
Previously we have shown that protein kinase C (PKC)-mediated reorganization of the actin cytoskeleton in smooth muscle cells is transmitted by the nonreceptor tyrosine kinase, Src. Several authors have described how 12-O- tetradecanoylphorbol-13-acetate(TPA) stimulation of cells results in an increase of Src activity, but the mechanism of the PKC-mediated Src activation is unknown. Using PKC isozymes purified from Spodoptera frugiperda insect cells, we show here that PKC is not able to activate Src directly. Our data reveal that the PKC-dependent Src activation occurs via the activation of the protein tyrosine phosphatase (PTP) PTPalpha. PTPalpha becomes activated in vivo after TPA stimulation. Further, we show that PKCdelta phosphorylates and activates only PTPalpha in vitro but not any other of the TPA-responsive PKC isozymes that are expressed in A7r5 rat aortic smooth muscle cells. To further substantiate our data, we show that cells lacking PKCdelta have a markedly reduced PTPalpha and Src activity after 12-O-tetradecanoylphorbol-13-acetate stimulation. These data support a model in which the main mechanism of 12-O-tetradecanoylphorbol-13- acetate-induced Src activation is the direct phosphorylation and activation of PTPalpha by PKCdelta, which in turn dephosphorylates and activates Src.