Redox-Induced Src Kinase and Caveolin-1 Signaling in TGF-β1-Initiated SMAD2/3 Activation and PAI-1 Expression
Redox-Induced Src Kinase and Caveolin-1 Signaling in TGF-β1-Initiated SMAD2/3 Activation and PAI-1 Expression
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DOI：
10.1371/journal.pone.0022896
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发表时间：
2011-07-28
期刊：
影响因子：
3.7
通讯作者：
Higgins, Paul J.
中科院分区：
文献类型：
--
作者：
Samarakoon, Rohan;Chitnis, Subhanir S.;Higgins, Paul J.
背景资料：纤溶酶原激活物抑制剂-1（派-1）是基于纤溶酶的细胞周蛋白水解级联的主要调节剂，其在人动脉斑块中显著增加，从而导致血管纤维化、动脉硬化和血栓形成，特别是在组织TGF-β 1升高的情况下。识别潜在的分子事件派-1诱导响应TGF-β 1可能会产生新的目标，用于治疗心血管疾病的主要发现：活性氧物种产生后5分钟内加入TGF-β 1静止血管平滑肌细胞（VSMC）导致pp 60（c-src）激活和派-1的表达。TGF-β 1刺激的Src激酶信号通过降低PPM 1A（一种最近鉴定的C-末端SMAD 2/3磷酸酶）的水平，维持VSMC中SMAD 3磷酸化的持续时间（但不是起始时间），从而维持SMAD 2/3处于活性状态，并保留派-1转录。与野生型细胞相比，三重Src激酶（c-Src，Yes，Fyn）-null成纤维细胞中PPM 1A水平的显著增加与响应TGF-β 1的SMAD 3磷酸化和派-1表达的降低一致。Rho-ROCK通路的激活由Src激酶介导，并且是TGF-β 1刺激的VSMC中派-1诱导所必需的。抑制Rho-ROCK信号传导阻断了TGF-β 1介导的核PPM 1A含量的降低，并有效地减弱了派-1表达。TGF-β 1诱导的派-1表达在caveolin-1-null细胞中检测不到，这与TGF-β 1处理的caveolin-1-缺陷细胞相对于其野生型对应物明显减少的Rho-GTP负载和SMAD 2/3磷酸化相关。Src激酶，此外，是关键的上游效应的小窝蛋白-1（Y14）磷酸化和启动下游signaling.Conclusions：TGF-β 1启动Src依赖小窝蛋白-1（Y14）磷酸化是一个关键的事件，在Rho-ROCK介导的抑制核PPM 1A水平的维持，从而SMAD 2/3依赖的派-1基因的转录。
Background: Plasminogen activator inhibitor-1 (PAI-1), a major regulator of the plasmin-based pericellular proteolytic cascade, is significantly increased in human arterial plaques contributing to vessel fibrosis, arteriosclerosis and thrombosis, particularly in the context of elevated tissue TGF-beta 1. Identification of molecular events underlying to PAI-1 induction in response to TGF-beta 1 may yield novel targets for the therapy of cardiovascular disease.Principal Findings: Reactive oxygen species are generated within 5 minutes after addition of TGF-beta 1 to quiescent vascular smooth muscle cells (VSMCs) resulting in pp60(c-src) activation and PAI-1 expression. TGF-beta 1-stimulated Src kinase signaling sustained the duration (but not the initiation) of SMAD3 phosphorylation in VSMC by reducing the levels of PPM1A, a recently identified C-terminal SMAD2/3 phosphatase, thereby maintaining SMAD2/3 in an active state with retention of PAI-1 transcription. The markedly increased PPM1A levels in triple Src kinase (c-Src, Yes, Fyn)-null fibroblasts are consistent with reductions in both SMAD3 phosphorylation and PAI-1 expression in response to TGF-beta 1 compared to wild-type cells. Activation of the Rho-ROCK pathway was mediated by Src kinases and required for PAI-1 induction in TGF-beta 1-stimulated VSMCs. Inhibition of Rho-ROCK signaling blocked the TGF-beta 1-mediated decrease in nuclear PPM1A content and effectively attenuated PAI-1 expression. TGF-beta 1-induced PAI-1 expression was undetectable in caveolin-1-null cells, correlating with the reduced Rho-GTP loading and SMAD2/3 phosphorylation evident in TGF-beta 1-treated caveolin-1-deficient cells relative to their wild-type counterparts. Src kinases, moreover, were critical upstream effectors of caveolin-1(Y14) phosphoryation and initiation of downstream signaling.Conclusions: TGF-beta 1-initiated Src-dependent caveolin-1(Y14) phosphorylation is a critical event in Rho-ROCK-mediated suppression of nuclear PPM1A levels maintaining, thereby, SMAD2/3-dependent transcription of the PAI-1 gene.