Smooth muscle differentiation marker gene expression is regulated by RhoA-mediated actin polymerization
Smooth muscle differentiation marker gene expression is regulated by RhoA-mediated actin polymerization
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DOI：
10.1074/jbc.m005505200
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发表时间：
2001-01-05
影响因子：
4.8
通讯作者：
Owens, GK
中科院分区：
文献类型：
--
作者：
Mack, CP;Somlyo, AV;Owens, GK
复杂的局部环境信号阵列，但细胞内信号通路和调控这一过程的转录机制在很大程度上是未知的。我们和其他人已经证明血清反应因子（SRF）有助于SMC特异性基因转录，并且由于小GTPase RhoA已被证明可以调节SRF，因此本研究的目的是验证RhoA信号传导是调节SMC分化的关键机制的假设。在大鼠主动脉SMC培养中，共表达组成活性RhoA可显著提高SMC特异性启动子SM22和SM α -肌动蛋白的活性，而C3转移酶的共表达可消除这些启动子的活性。Rho激酶抑制剂Y-27632 （10 muM）抑制应激纤维形成或latrunculin B （0.5 muM）抑制肌动蛋白聚合显著降低SM22和SM α -肌动蛋白启动子的活性。与此相反，茉莉烯内酯（0.5 muM）增加肌动蛋白聚合，SM22和SM α -肌动蛋白启动子活性分别提高了22倍和13倍。上述干预措施对依赖srf的c-fos启动子或不依赖srf的最小胸苷激酶启动子的转录影响很小或没有影响。综上所述，这些研究结果表明，在SMC中，rhoa依赖的肌动蛋白细胞骨架调控通过调节srf依赖的转录来选择性地调节SMC分化标记基因的表达。结果还表明，RhoA信号可能是调节SMC分化的多种信号通路的汇聚点。
complex array of local environmental cues, but the intracellular signaling pathways and the transcription mechanisms that regulate this process are largely unknown. We and others have shown that serum response factor (SRF) contributes to SMC-specific gene transcription, and because the small GTPase RhoA has been shown to regulate SRF, the goal of the present study was to test the hypothesis that RhoA signaling is a critical mechanism for regulating SMC differentiation. Coexpression of constitutively active RhoA in rat aortic SMC cultures significantly increased the activity of the SMC-specific promoters, SM22 and SM alpha -actin, whereas coexpression of C3 transferase abolished the activity of these promoters. Inhibition of either stress fiber formation with the Rho kinase inhibitor Y-27632 (10 muM) or actin polymerization with latrunculin B (0.5 muM) significantly decreased the activity of SM22 and SM alpha -actin promoters. In contrast, increasing actin polymerization with jasplakinolide (0.5 muM) increased SM22 and SM alpha -actin promoter activity by 22-fold and 13-fold, respectively. The above interventions had little or no effect on the transcription of an SRF-dependent c-fos promoter or on a minimal thymidine kinase promoter that is not SRF-dependent. Taken together, the results of these studies indicate that in SMC, RhoA-dependent regulation of the actin cytoskeleton selectively regulates SMC differentiation marker gene expression by modulating SRF-dependent transcription. The results also suggest that RhoA signaling may serve as a convergence point for the multiple signaling pathways that regulate SMC differentiation.