Smad3 mediates transforming growth factor-β-induced α-smooth muscle actin expression
Smad3 mediates transforming growth factor-β-induced α-smooth muscle actin expression
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DOI：
10.1165/rcmb.2003-0063oc
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发表时间：
2003-09-01
影响因子：
6.4
通讯作者：
Phan, SH
中科院分区：
文献类型：
--
作者：
Hu, B;Wu, Z;Phan, SH
转化生长因子-β（TGF-β）诱导的α-平滑肌肌动蛋白（ASMA）表达是肌成纤维细胞从成纤维细胞分化的关键指标。最近的研究表明，TGF-β控制元件在TGF-β对ASMA基因启动子的调节中是重要的。在这项研究中，Smad 3的作用，Smad途径的一个关键组成部分，介导TGF-β信号调节ASMA基因的表达，进行了调查。Smad家族的所有成员都在大鼠肺成纤维细胞中表达，TGF-β 1处理后Smad 3表达升高。转染Smad 3表达质粒显著增加Smad 3和ASMA蛋白表达，而转染反义Smad 3质粒抑制Smad 3和ASMA表达。当克隆的大鼠ASMA启动子-荧光素酶报告基因构建体用于监测ASMA基因的转录激活时，注意到类似的效果。电泳迁移率变动分析和DNA亲和沉淀表明Smad 3结合到至少两个区域的启动子含有CAGA基序，称为Smad 3结合元件（SBE）。其中一个SBE的突变显著降低了启动子活性，表明该SBE具有功能性作用。总之，这些发现表明Smad 3在肌成纤维细胞分化中TGF-β调节ASMA基因表达中的作用。
Transforming growth factor-beta (TGF-beta)-induced a-smooth muscle actin (ASMA) expression is a key indicator of myofibroblast differentiation from fibroblasts. Recent studies suggest that a TGF-beta control element is important in the regulation of the ASMA gene promoter by TGF-beta. In this study, the role of Smad3, a key component of the Smad pathway that mediates TGF-beta signaling in regulation of ASMA gene expression, is investigated. All members of the Smad family were expressed in rat lung fibroblasts, and Smad3 expression was elevated upon TGF-beta(1) treatment. Transfection with a Smad3-expressing plasmid markedly increased Smad3 and ASMA protein expression, whereas transfection with an antisense Smad3 plasmid suppressed Smad3 and ASMA expression. Similar effects were noted when the cloned rat ASMA promoter-luciferase reporter gene construct was used to monitor transcriptional activation of the ASMA gene. Electrophoretic mobility shift assays and DNA affinity precipitation indicated Smad3 binding to at least two regions of the promoter containing CAGA motifs, termed Smad3-binding elements (SBEs). Mutation of one of the SBEs decreased promoter activity significantly, indicative of a functional role for this SBE. Taken together, these findings suggest a role for Smad3 in TGF-beta regulation of ASMA gene expression in myofibroblast differentiation.