Egr-1 is activated in endothelial cells exposed to fluid shear stress and interacts with a novel shear-stress-response element in the PDGF A-chain promoter
Egr-1 is activated in endothelial cells exposed to fluid shear stress and interacts with a novel shear-stress-response element in the PDGF A-chain promoter
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DOI：
10.1161/01.atv.17.10.2280
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发表时间：
1997-10-01
影响因子：
8.7
通讯作者：
Collins, T
中科院分区：
文献类型：
--
作者：
Khachigian, LM;Anderson, KR;Collins, T
血管内皮细胞暴露于流体机械力可以调节许多与血管生理学和病理生理学有关的基因的表达。在此，我们报道了在稳定的生理水平的层流切应力(10dyn/cm(2))下，在转录水平上诱导了培养的牛主动脉内皮细胞的血小板衍生生长因子(PDGF)A链基因的表达。人PDGF-A启动子的5‘端缺失分析表明，剪切诱导报告基因的表达需要TATA盒附近的GC富集区。该元件赋予异源启动子-报告者结构剪切诱导性，否则该结构对剪切力不敏感。在剪切诱导PDGF-A表达之前，快速和瞬时诱导即刻早期基因EGR-1的表达，该基因与富含GC的序列结合。凝胶位移研究表明，剪切诱导的Egr-1以一种特定的和时间依赖的方式结合到PDGF-A启动子的近端，取代了Sp1的重叠识别元件。Egr-1和Sp1的重叠结合位点也出现在其他几个内皮基因的近端启动子中，包括转化生长因子-β(1)和组织因子，它们的表达受剪切力的调节。这些发现将PDGF-A启动子近端的Egr-1结合位点定义为剪切应力响应元件，并提示剪切刺激的Egr-1基因表达可能是诱导暴露于生物机械力的各种其他内皮基因的统一主题。
Exposure of vascular endothelial cells to fluid mechanical forces can modulate the expression of many genes involved in vascular physiology and pathophysiology. Here, we report that platelet-derived growth factor (PDGF) A-chain gene expression is induced at the level of transcription in cultured bovine aortic endothelial cells exposed to a physiologic level of steady laminar shear stress (10 dyn/cm(2)). 5' Deletion analysis of the human PDGF-A promoter revealed that a GC-rich region near the TATA box was required for shear-inducible reporter gene expression. This element conferred shear inducibility onto a heterologous promoter-reporter construct that was otherwise unresponsive to shear stress. The induction of PDGF-A expression by shear was preceded by rapid and transient induction in the expression of the immediate-early gene, egr-1, which binds to GC-rich sequences. Gel shift studies indicated that shear-induced Egr-1 bound to the proximal PDGF-A promoter in a specific and time-dependent manner, displacing Sp1 from their overlapping recognition elements. Overlapping consensus binding sites for Egr-1 and Sp1 also appear in the proximal promoters of several other endothelial genes, including transforming growth factor-beta(1) and tissue factor, whose expression is modulated by shear stress. These findings define the Egr-1 binding site in the proximal PDGF-A promoter as a shear-stress-responsive element and suggest that shear-stimulated Egr-1 gene expression may be a unifying theme in the induction of various other endothelial genes exposed to biomechanical forces.