The RhoA/Rho kinase pathway regulates nuclear localization of serum response factor
The RhoA/Rho kinase pathway regulates nuclear localization of serum response factor
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DOI：
10.1165/rcmb.2002-0206oc
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发表时间：
2003-07-01
影响因子：
6.4
通讯作者：
Solway, J
中科院分区：
文献类型：
--
作者：
Liu, HW;Halayko, AJ;Solway, J
RhoA及其下游靶点Rho激酶调节血清反应因子（SRF）依赖的骨骼肌和平滑肌基因表达。我们以前报道，长期血清剥夺减少平滑肌收缩装置编码基因的转录，通过重新分配SRF的核。由于血清成分刺激RhoA活性，这些观察结果表明，RhoA/Rho激酶途径调节SRF依赖性平滑肌基因转录的一部分，通过控制SRF亚细胞定位的假设。我们目前的研究结果支持这一假设：共转染培养的气道肌细胞与质粒表达组成型活性RhoAV 14选择性增强转录从SM 22和平滑肌肌球蛋白重链启动子和从一个纯粹的SRF依赖性启动子，但没有影响转录从MSV-LTR启动子或从AP 2依赖性启动子。相反，通过与表达显性阴性RhoAN 19的质粒共转染、与表达梭菌C3毒素的质粒共转染或与Rho激酶抑制剂Y-27632孵育来抑制RhoA/Rho激酶途径，都选择性地降低了SRF依赖性平滑肌启动子活性。此外，用Y-27632处理选择性地减少了来自核提取物的SRF与其共有DNA靶标的结合，选择性地减少了核SRF蛋白含量，并部分地将SRF从核重新分配到细胞质，如定量免疫细胞化学所揭示的。用减少肌动蛋白聚合的latrunculin B处理培养的气道肌细胞，也引起SRF部分重新分布到细胞质中。总之，这些结果首次证明RhoA/Rho激酶通路部分通过调节SRF的亚细胞定位来控制分化的平滑肌细胞中的平滑肌基因转录。可以想象，RhoA/Rho激酶途径通过其对肌动蛋白聚合动力学的影响来影响SRF定位。
RhoA and its downstream target Rho kinase regulate serum response factor (SRF)-dependent skeletal and smooth muscle gene expression. We previously reported that long-term serum deprivation reduces transcription of smooth muscle contractile apparatus encoding genes, by redistributing SRF out of the nucleus. Because serum components stimulate RhoA activity, these observations suggest the hypothesis that the RhoA/Rho kinase pathway regulates SRF-dependent smooth muscle gene transcription in part by controlling SRF subcellular localization. Our present results support this hypothesis: cotransfection of cultured airway myocytes with a plasmid expressing constitutively active RhoAV14 selectively enhanced transcription from the SM22 and smooth muscle myosin heavy chain promoters and from a purely SRF-dependent promoter, but had no effect on transcription from the MSV-LTR promoter or from an AP2-dependent promoter. Conversely, inhibition of the RhoA/Rho kinase pathway by cotransfection with a plasmid expressing dominant negative RhoAN19, by cotransfection with a plasmid expressing Clostridial C3 toxin, or by incubation with the Rho kinase inhibitor, Y-27632, all selectively reduced SRF-dependent smooth muscle promoter activity. Furthermore, treatment with Y-27632 selectively reduced binding of SRF from nuclear extracts to its consensus DNA target, selectively reduced nuclear SRF protein content, and partially redistributed SRF from nucleus to cytoplasm, as revealed by quantitative immunocytochemistry. Treatment of cultured airway myocytes with latrunculin B, which reduces actin polymerization, also caused partial redistribution of SRF into the cytoplasm. Together, these results demonstrate for the first time that the RhoA/Rho kinase pathway controls smooth muscle gene transcription in differentiated smooth muscle cells, in part by regulating the subcellular localization of SRF. It is conceivable that the RhoA/Rho kinase pathway influences SRF localization through its effect on actin polymerization dynamics.