Role of p38 MAPK and MAPKAPK-2 in angiotensin II-induced Akt activation in vascular smooth muscle cells
Role of p38 MAPK and MAPKAPK-2 in angiotensin II-induced Akt activation in vascular smooth muscle cells
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DOI：
10.1152/ajpcell.00439.2003
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发表时间：
2004-08-01
影响因子：
5.5
通讯作者：
Griendling, KK
中科院分区：
文献类型：
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作者：
Taniyama, Y;Ushio-Fukai, M;Griendling, KK
血管紧张素II激活血管平滑肌细胞（VSMC）中的多种信号传导途径，包括MAPKs和Akt，这两者都是肥大所需的。然而，很少有人知道这些激酶之间的关系或上游激活Akt。在这项研究中，我们测试的假设，活性氧（ROS）敏感激酶p38 MAPK和其底物MAPKAPK-2介导的VSMCs Akt激活。在未受刺激的VSMC中，Akt和p38 MAPK是组成性相关的，并且在血管紧张素II刺激后仍然如此。SB-203580对p38 MAPK活性的抑制以剂量依赖性方式抑制Ser（473）上的Akt磷酸化，但不抑制Thr（308）。血管紧张素II诱导的MAPKAPK-2磷酸化也被SB-203580以及ROS抑制剂减弱。此外，血管紧张素II刺激MAPKAPK-2与Akt-p38 MAPK复合物的关联，并且体外激酶测定显示MAPKAPK-2免疫沉淀VSMC裂解物以血管紧张素II诱导的方式磷酸化重组Akt。最后，MAPKAPK-2肽抑制剂的细胞内递送阻断Ser（473）上的Akt磷酸化。这些结果表明，p38 MAPK-MAPKAPK-2途径介导Akt激活血管紧张素II在这些细胞中招募活性MAPKAPK-2的信号复合物，包括Akt和p38 MAPK。通过这种机制，p38 MAPK赋予ROS对Akt的敏感性并促进下游信号传导。这些结果为一种新型信号复合物提供了证据，该复合物可能有助于在空间上组织VSMC中肥大相关的ROS敏感信号。
Angiotensin II activates a variety of signaling pathways in vascular smooth muscle cells (VSMCs), including the MAPKs and Akt, both of which are required for hypertrophy. However, little is known about the relationship between these kinases or about the upstream activators of Akt. In this study, we tested the hypothesis that the reactive oxygen species (ROS)-sensitive kinase p38 MAPK and its substrate MAPKAPK-2 mediate Akt activation in VSMCs. In unstimulated VSMCs, Akt and p38 MAPK are constitutively associated and remain so after angiotensin II stimulation. Inhibition of p38 MAPK activity with SB-203580 dose-dependently inhibits Akt phosphorylation on Ser(473), but not Thr(308). Angiotensin II-induced phosphorylation of MAPKAPK-2 is also attenuated by SB-203580, as well as by inhibitors of ROS. In addition, angiotensin II stimulates the association of MAPKAPK-2 with the Akt-p38 MAPK complex, and an in vitro kinase assay shows that MAPKAPK-2 immunoprecipitates of VSMC lysates phosphorylate recombinant Akt in an angiotensin II-inducible manner. Finally, intracellular delivery of a MAPKAPK-2 peptide inhibitor blocks Akt phosphorylation on Ser(473). These results suggest that the p38 MAPK-MAPKAPK-2 pathway mediates Akt activation by angiotensin II in these cells by recruiting active MAPKAPK-2 to a signaling complex that includes both Akt and p38 MAPK. Through this mechanism, p38 MAPK confers ROS sensitivity to Akt and facilitates downstream signaling. These results provide evidence for a novel signaling complex that may help to spatially organize hypertrophy-related, ROS-sensitive signaling in VSMCs.