Opposite smad and chicken ovalbumin upstream promoter transcription factor inputs in the regulation of the collagen VII gene promoter by transforming growth factor-β
Opposite smad and chicken ovalbumin upstream promoter transcription factor inputs in the regulation of the collagen VII gene promoter by transforming growth factor-β
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DOI：
10.1074/jbc.m402178200
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发表时间：
2004-05-28
影响因子：
4.8
通讯作者：
Massagué, J
中科院分区：
文献类型：
--
作者：
Calonge, MJ;Seoane, J;Massagué, J
表皮基底膜的关键组分VII型胶原蛋白由角质形成细胞和成纤维细胞产生，并且其产生由细胞因子转化生长因子-β（TGF-β）刺激。基因COL 7A 1通过Smad转录因子与AP 1合作被TGF-β激活。在这里，我们报告了以前没有想到的复杂程度，在这一监管过程。我们提供的证据表明，TGF-β可以激活COL 7A 1启动子通过两个不同的输入操作通过一个共同的区域的启动子。一个输入是由TGF-β诱导的Smad复合物通过两个Smad结合元件提供的，这两个Smad结合元件根据细胞类型冗余地发挥作用。第二个输入是通过从鸡卵清蛋白上游启动子转录因子（COUP-TF）介导的转录抑制中释放COL 7A 1启动子来提供的。我们确定COUP-TFI和- TFII作为在表达文库筛选中与COL 7A 1启动子的TGF-β响应区结合的因子。COUP-TF独立于Smad或AP 1与两个Smad结合元件之间的位点结合，并抑制该启动子的基础和TGF-β刺激的活性。我们提供的证据表明，内源性COUP-TF活性抑制COL 7A 1启动子。此外，我们表明，TGF-β添加导致角质形成细胞和成纤维细胞中COUP-TF表达的快速和深刻的下调。结果表明，TGF-β信号传导可能通过抵消相反的Smad和COUP-TF之间的平衡来对COL 7A 1施加严格的控制。
A critical component of the epidermal basement membrane, collagen type VII, is produced by keratinocytes and fibroblasts, and its production is stimulated by the cytokine transforming growth factor-beta (TGF-beta). The gene, COL7A1, is activated by TGF-beta via Smad transcription factors in cooperation with AP1. Here we report a previously unsuspected level of complexity in this regulatory process. We provide evidence that TGF-beta may activate the COL7A1 promoter by two distinct inputs operating through a common region of the promoter. One input is provided by TGF-beta-induced Smad complexes via two Smad binding elements that function redundantly depending on the cell type. The second input is provided by relieving the COL7A1 promoter from chicken ovalbumin upstream promoter transcription factor (COUP-TF)-mediated transcriptional repression. We identified COUP-TFI and - TFII as factors that bind to the TGF-beta-responsive region of the COL7A1 promoter in an expression library screening. COUP-TFs bind to a site between the two Smad binding elements independently of Smad or AP1 and repress the basal and TGF-beta-stimulated activities of this promoter. We provide evidence that endogenous COUP-TF activity represses the COL7A1 promoter. Furthermore, we show that TGF-beta addition causes a rapid and profound down-regulation of COUP-TF expression in keratinocytes and fibroblasts. The results suggest that TGF-beta signaling may exert tight control over COL7A1 by offsetting the balance between opposing Smad and COUP-TFs.