Singh Nikhlesh K, Janjanam Jagadeesh, Rao Gadiparthi N
From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163.
From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163.
J Biol Chem. 2017 Aug 25;292(34):14080-14091. doi: 10.1074/jbc.M117.777896. Epub 2017 Jun 27.
Although the involvement of Rho proteins in the pathogenesis of vascular diseases is well studied, little is known about the role of their upstream regulators, the Rho guanine nucleotide exchange factors (RhoGEFs). Here, we sought to identify the RhoGEFs involved in monocyte chemotactic protein 1 (MCP1)-induced vascular wall remodeling. We found that, among the RhoGEFs tested, MCP1 induced tyrosine phosphorylation of p115 RhoGEF but not of PDZ RhoGEF or leukemia-associated RhoGEF in human aortic smooth muscle cells (HASMCs). Moreover, p115 RhoGEF inhibition suppressed MCP1-induced HASMC migration and proliferation. Consistent with these observations, balloon injury (BI) induced p115 RhoGEF tyrosine phosphorylation in rat common carotid arteries, and siRNA-mediated down-regulation of its levels substantially attenuated BI-induced smooth muscle cell migration and proliferation, resulting in reduced neointima formation. Furthermore, depletion of p115 RhoGEF levels also abrogated MCP1- or BI-induced Rac1-NFATc1-cyclin D1-CDK6-PKN1-CDK4-PAK1 signaling, which, as we reported previously, is involved in vascular wall remodeling. Our findings also show that protein kinase N1 (PKN1) downstream of Rac1-cyclin D1/CDK6 and upstream of CDK4-PAK1 in the p115 RhoGEF-Rac1-NFATc1-cyclin D1-CDK6-PKN1-CDK4-PAK1 signaling axis is involved in the modulation of vascular wall remodeling. Of note, we also observed that CCR2-G-Fyn signaling mediates MCP1-induced p115 RhoGEF and Rac1 GTPase activation. These findings suggest that p115 RhoGEF is critical for MCP1-induced HASMC migration and proliferation and for injury-induced neointima formation by modulating Rac1-NFATc1-cyclin D1-CDK6-PKN1-CDK4-PAK1 signaling.
尽管Rho蛋白在血管疾病发病机制中的作用已得到充分研究，但其上游调节因子Rho鸟嘌呤核苷酸交换因子（RhoGEFs）的作用却鲜为人知。在此，我们试图鉴定参与单核细胞趋化蛋白1（MCP1）诱导的血管壁重塑的RhoGEFs。我们发现，在测试的RhoGEFs中，MCP1可诱导人主动脉平滑肌细胞（HASMCs）中p115 RhoGEF的酪氨酸磷酸化，但不诱导PDZ RhoGEF或白血病相关RhoGEF的酪氨酸磷酸化。此外，p115 RhoGEF抑制可抑制MCP1诱导的HASMC迁移和增殖。与这些观察结果一致，球囊损伤（BI）可诱导大鼠颈总动脉中p115 RhoGEF酪氨酸磷酸化，而siRNA介导的其水平下调可显著减弱BI诱导的平滑肌细胞迁移和增殖，从而减少新生内膜形成。此外，p115 RhoGEF水平的降低还消除了MCP1或BI诱导的Rac1-NFATc1-细胞周期蛋白D1-CDK6-PKN1-CDK4-PAK1信号传导，正如我们之前报道的，该信号传导参与血管壁重塑。我们的研究结果还表明，在p115 RhoGEF-Rac1-NFATc1-细胞周期蛋白D1-CDK6-PKN1-CDK4-PAK1信号轴中，Rac1-细胞周期蛋白D1/CDK6下游和CDK4-PAK1上游的蛋白激酶N1（PKN1）参与血管壁重塑的调节。值得注意的是，我们还观察到CCR2-G-Fyn信号传导介导MCP1诱导的p115 RhoGEF和Rac1 GTP酶激活。这些发现表明，p115 RhoGEF通过调节Rac1-NFATc1-细胞周期蛋白D1-CDK6-PKN1-CDK4-PAK1信号传导，对MCP1诱导的HASMC迁移和增殖以及损伤诱导的新生内膜形成至关重要。
