Molecular mechanisms of decreased smooth muscle differentiation marker expression after vascular injury
Molecular mechanisms of decreased smooth muscle differentiation marker expression after vascular injury
复制标题
DOI：
10.1172/jci10522
复制
发表时间：
2000-11-01
影响因子：
15.9
通讯作者：
Owens, GK
中科院分区：
文献类型：
--
作者：
Regan, CP;Adam, PJ;Owens, GK
虽然血管平滑肌细胞（VSMCs）的表型调节对血管病变的发生和发展有促进作用这一点已得到充分证实，但对于体内表型调节的分子机制却知之甚少。在此我们表明血管损伤会降低VSMC分化标记基因的转录，并且我们确定了可能介导这种降低的顺式调控元件。我们利用携带平滑肌α -肌动蛋白、平滑肌肌球蛋白重链或SM22α启动子 - β -半乳糖苷酶报告基因转基因的小鼠颈动脉导丝损伤模型，在损伤后7天和14天收集动脉，并评估内源性蛋白质和mRNA水平以及β -半乳糖苷酶活性的变化。所有标记物的内源性水平在损伤后7天均降低，并在14天恢复到接近对照水平。所有品系中的β -半乳糖苷酶染色都呈现出类似的模式，这表明转录下调导致了损伤诱导的降低。为了开始剖析这种反应，我们对SM22α启动子转基因中一个假定的富含G/C的阻遏物进行了突变，发现这种突变显著减弱了损伤诱导的下调。因此，转录下调导致了损伤诱导的VSMC分化标记物的降低，这种效应可能部分是通过一个富含G/C的阻遏元件介导的。
While it is well established that phenotypic modulation of vascular smooth muscle cells (VSMCs) contributes to the development and progression of vascular lesions, little is known regarding the molecular mechanisms of phenotypic modulation in vivo. Here we show that vascular injury reduces transcription of VSMC differentiation marker genes, and we identify cis regulatory elements that may mediate this decrease. Using a carotid wire-injury model in mice carrying transgenes for smooth muscle alpha -actin, smooth muscle myosin heavy chain, or a SM22 alpha promoter-beta -gal reporter, we collected arteries 7 and 14 days after injury and assessed changes in endogenous protein and mRNA levels and in beta -gal activity. Endogenous levels for all markers were decreased 7 days after injury and returned to nearly control levels by 14 days. beta -gal staining in all Lines followed a similar pattern, suggesting that transcriptional downregulation contributed to the injury-induced decreases. To begin to dissect this response, we mutated a putative G/C-rich repressor in the SM22 alpha promoter transgene and found that this mutation significantly attenuated injury-induced downregulation. Hence, transcriptional downregulation contributes to injury-induced decreases in VSMC differentiation markers, an effect that may be partially mediated through a G/C-rich repressor element.