全反式维甲酸在平滑肌细胞中上调apelin基因表达的分子机制

Role and mechanism of all-trans retinoic acid in up-regulating apelin expression in vascular smooth muscle cells

本文旨在研究全反式维甲酸(all-trans retinoic acid,ATRA)在血管平滑肌细胞(vascular smooth muscle cell,VSMC)中对apelin基因表达的影响及分子机制。我们用RT-PCR、实时定量PCR和免疫印迹分析检测ATRA对VSMC中apelin基因表达的影响,然后在VSMC中用小干扰RNA转染下调内源性维甲酸受体α(retinoic acid receptorα,RARα)或用腺病毒载体过表达RARα后,检测ATRA对apelin基因表达的影响。结果显示ATRA能以时间和浓度依赖的方式诱导apelin基因的表达,同时RARα表达水平也显著升高,但RARβ和RARγ表达水平无显著变化。利用小干扰RNA下调内源性RARα或用RARα选择性抑制剂Ro 41-5253抑制RARα活性后,再用ATRA刺激VSMC,ATRA对apelin基因表达的诱导作用受到显著抑制,而过表达RARα,则可促进apelin的表达升高。以上结果表明,ATRA可以上调VSMC中apelin基因表达水平,其分子机制是通过其核受体RARα介导完成的。

This study was aimed to investigate the mechanism of all-trans retinoic acid （ATRA） up-regulating apelin expression in vascular smooth muscle cells （VSMCs）. The effect of ATRA on apelin expression in the VSMCs was investigated by RT-PCR, real-time PCR and Western blot analysis. To further define whether retinoic acid receptor ct （RARer） mediated the induction of apelin by ATRA, endogenous RARer was down regulated by transfection of siRNA against RARer （si-RARα） or RARα was over-expressed by infection of the adenovirus vector pAd-GFP-RARct in the VSMCs. The results showed that ATRA significantly induced apelin expression in a time- and dose-dependent manner in the VSMCs. Although RARα expression was increased in a time-dependent manner, the expressions of RARα and RAR7 were little changed by the ATRA treatment. When VSMCs were treated with a RARer antagonist Ro 41- 5253 prior to the addition of ATRA, or si-RARct was used to down regulate endogenous RARer expression, the blockade of RARα signaling partially reduced the response of apelin to ATRA. Moreover, RARα over-expression, induced by infection of pAd-GFP-RARα, further increased the induction of apelin by ATRA. In conclusion, ATRA may up-regulate apelin expression in VSMCs, and the mechanism may be RARct dependent.