Serine 34 phosphorylation of rho guanine dissociation inhibitor (RhoGDIalpha) links signaling from conventional protein kinase C to RhoGTPase in cell adhesion.
Serine 34 phosphorylation of rho guanine dissociation inhibitor (RhoGDIalpha) links signaling from conventional protein kinase C to RhoGTPase in cell adhesion.
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DOI：
10.1074/jbc.m109.098129
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发表时间：
2010-07-23
期刊：
影响因子：
--
通讯作者：
Couchman JR
中科院分区：
文献类型：
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作者：
Dovas A;Choi Y;Yoneda A;Multhaupt HA;Kwon SH;Kang D;Oh ES;Couchman JR
传统的蛋白激酶C （PKC）异构体是调节许多信号网络的必需丝氨酸/苏氨酸激酶。在细胞粘附位点，PKCα可以通过对rhogtpase的影响影响肌动蛋白细胞骨架，但中间步骤尚不清楚。RhoGTPase功能的一个重要调节因子是多功能鸟嘌呤核苷酸解离抑制剂RhoGDIα，它以非活性形式隔离几个相关的RhoGTPase，但它也可能通过与肌动蛋白相关蛋白的相互作用来靶向它们。本研究表明，常规PKC磷酸化RhoGDIα的丝氨酸34，导致RhoA的亲和力特异性降低，而不是Rac1或Cdc42。RhoGDIα磷酸化的机制是明确的，需要激酶和磷脂酰肌醇4,5-二磷酸，这与最近的证据一致，即肌醇可以激活、定位和定向膜中的PKCα。磷酸化特异性抗体揭示了几种对粘附事件敏感的细胞类型的内源性磷酸化，例如由肝细胞生长因子引发的粘附事件。磷酸化对PKC抑制也很敏感。结合荧光共振能量转移显微镜检测GTP-RhoA水平，数据揭示了细胞粘附中连接两种基本介质（传统PKC和RhoA）的共同途径。
Conventional protein kinase C (PKC) isoforms are essential serine/threonine kinases regulating many signaling networks. At cell adhesion sites, PKCα can impact the actin cytoskeleton through its influence on RhoGTPases, but the intermediate steps are not well known. One important regulator of RhoGTPase function is the multifunctional guanine nucleotide dissociation inhibitor RhoGDIα that sequesters several related RhoGTPases in an inactive form, but it may also target them through interactions with actin-associated proteins. Here, it is demonstrated that conventional PKC phosphorylates RhoGDIα on serine 34, resulting in a specific decrease in affinity for RhoA but not Rac1 or Cdc42. The mechanism of RhoGDIα phosphorylation is distinct, requiring the kinase and phosphatidylinositol 4,5-bisphosphate, consistent with recent evidence that the inositide can activate, localize, and orient PKCα in membranes. Phosphospecific antibodies reveal endogenous phosphorylation in several cell types that is sensitive to adhesion events triggered, for example, by hepatocyte growth factor. Phosphorylation is also sensitive to PKC inhibition. Together with fluorescence resonance energy transfer microscopy sensing GTP-RhoA levels, the data reveal a common pathway in cell adhesion linking two essential mediators, conventional PKC and RhoA.