Smad proteins regulate transcriptional induction of the SM22α gene by TGF-β
Smad proteins regulate transcriptional induction of the SM22α gene by TGF-β
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DOI：
10.1093/nar/gkg224
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发表时间：
2003-02-15
影响因子：
14.9
通讯作者：
Lechleider, RJ
中科院分区：
文献类型：
--
作者：
Chen, SY;Kulik, M;Lechleider, RJ
Smad蛋白从转化生长因子-β（TGF-β）受体传递信号并调节靶基因的转录。TGF-β参与平滑肌细胞特异性基因SM 22 α的调节，但关于Smads如何参与SM 22 α基因转录的研究知之甚少。在这份报告中，我们证明了TGF-β激活的SM 22 α启动子是Smad依赖于C3 H10 T1/2细胞，BALB 3 T3细胞和神经嵴Monc-1细胞。我们发现，启动子区从-162到+41足以上调报告基因后，TGF-β诱导。Smad 3、Smad 1和Smad 4存在于TGF-β诱导型复合物中，这些复合物与含有Smad结合位点（SBS）和美狄亚盒的区域结合。SBS和美狄亚盒都是复合物形成所必需的，并且在功能上是重要的。Smad 4限制TGF-β诱导，而Smad 3，而不是Smad 1，显著有助于最大激活。时程荧光素酶测定和时程凝胶迁移率变动测定揭示，Smad 3/4复合物主要负责SM 22 α启动子对TGF-β诱导的即时反应，并且还有助于最大启动子活性。我们进一步证明了AP-1元件有助于TGF-β诱导SM 22 α启动子。
Smad proteins transduce signals from transforming growth factor-beta (TGF-beta) receptors and regulate transcription of target genes. TGF-beta is implicated in the regulation of the smooth muscle cell specific gene SM22alpha, but little is known about how Smads are involved in SM22alpha gene transcription. In this report, we demonstrate that TGF-beta activation of the SM22alpha promoter is Smad dependent in C3H10T1/2 cells, BALB 3T3 cells and neural crest Monc-1 cells. We find that the promoter region from -162 to +41 is sufficient to up-regulate the reporter gene upon TGF-beta induction. Smad3, Smad1 and Smad4 are found in TGF-beta inducible complexes that bind to a region containing a Smad binding site (SBS) and a medea box. Both the SBS and medea box are necessary for complex formation and are functionally important. Smad4 is limiting for TGF-beta induction, and Smad3, but not Smad1, significantly contributes to maximal activation. Time course luciferase assays and time course gel mobility shift assays reveal that the Smad3/4 complex is largely responsible for the immediate response of the SM22alpha promoter to TGF-beta induction, and also contributes to the maximal promoter activity. We further demonstrate that AP-1 elements contribute to induction of the SM22alpha promoter by TGF-beta.