Sphingosine 1-phosphate receptor 2 signals through leukemia-associated RhoGEF (LARG), to promote smooth muscle cell differentiation.
Sphingosine 1-phosphate receptor 2 signals through leukemia-associated RhoGEF (LARG), to promote smooth muscle cell differentiation.
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DOI：
10.1161/atvbaha.110.209395
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发表时间：
2010-09
期刊：
影响因子：
--
通讯作者：
Mack CP
中科院分区：
文献类型：
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作者：
Medlin MD;Staus DP;Dubash AD;Taylor JM;Mack CP
本研究的目的是确定 S1P 激活 SMC 中 RhoA 的信号通路，并评估该通路对 SMC 表型调节的贡献。通过结合受体特异性激动剂和拮抗剂，我们确定 S1PR2 是调节 SMC 分化标记基因表达的主要 S1P 受体亚型。基于 S1PR2 的已知偶联特性以及我们证明 Gα12 或 Gα13 的过度表达会增加 SMC 特异性启动子活性，我们接下来测试了 S1P 在 SMC 中的作用是否由 RGS-RhoGEF（LARG、PRG、p115）介导。尽管在 10T1/2 细胞中过表达时，每个 RGS-RhoGEF 都会增强肌动蛋白聚合、MRTF-A 核定位和 SMC 特异性启动子活性，但 LARG 表现出最强的效果，并且是 SMC 中唯一被 S1P 激活的 RGS-RhoGEF。重要的是，siRNA 介导的 LARG 耗竭显着抑制了 S1P 对 RhoA 和 SMC 分化标志物基因表达的激活。 LARG 的敲低对 SMC 增殖没有影响，但通过划痕和 Transwell 实验测量，促进了 SMC 迁移。这些数据表明 SMC 中 RhoA 的 S1PR2 依赖性激活是由 LARG 介导的，并且这种信号机制促进分化的 SMC 表型。
The goals of this study were to identify the signaling pathway by which S1P activates RhoA in SMC and to evaluate the contribution of this pathway to the regulation of SMC phenotype. Using a combination of receptor-specific agonists and antagonists we identified S1PR2 as the major S1P receptor sub-type that regulates SMC differentiation marker gene expression. Based upon the known coupling properties of S1PR2 and our demonstration that over-expression of Gα12 or Gα13 increased SMC specific promoter activity, we next tested whether the effects of S1P in SMC were mediated by the RGS-RhoGEFs (LARG, PRG, p115). Although each of the RGS-RhoGEFs enhanced actin polymerization, MRTF-A nuclear localization, and SMC-specific promoter activity when over-expressed in 10T1/2 cells, LARG exhibited the most robust effect and was the only RGS-RhoGEF activated by S1P in SMC. Importantly, siRNA-mediated depletion of LARG significantly inhibited the activation of RhoA and SMC differentiation marker gene expression by S1P. Knockdown of LARG had no effect on SMC proliferation, but promoted SMC migration as measured by scratch wound and transwell assays. These data indicate that S1PR2-dependent activation of RhoA in SMC is mediated by LARG and that this signaling mechanism promotes the differentiated SMC phenotype.