MALAT1/miR-204/Smad4信号通路介导间质细胞成骨分化诱导主动脉瓣钙化机制研究

Aortic valve calcification (AVC) is a common clinical problem with increased morbidity and mortality and afflicts our aging population. However, the mechanism of AVC has not been thoroughly understood. Our previous study showed that the down-regulation of miR-204 is closely associated with the progression of AVC, and could be used as a target for exploring novel treatment strategies. The precise molecular mechanism involved in the effects of miR-204 on AVC has still to be fully discovered. Recently, lncRNAs have been reported to act as an effective miRNA sponge and affect miRNA target gene activity. Bioinformatic analysis shows that the lncRNA MALAT1 have a miR-204 binding site, and that miR-204 can specifically bind to the 3’-untranslated region (3’-UTR) of Smad4. We also found that MALAT1 was markedly downregulated in BMP-2-stimulated aortic valve interstitial cells (VICs), and that over-expression of MALAT1 in VICs resulted in decreased miR-204 level and thereby increased the protein expression of Smad4. Base on these findings, this study will systematically evaluate the expressions of MALAT1, miR-204 and Smad4 in AVC, investigate the influence of MALAT1/miR-204/miR-204 signal pathway on the osteoblast differentiation of VICs, and thus provide novel approaches for the treatment of AVC.

主动脉瓣钙化发病率逐年增高，严重危害人类健康。我们前期工作发现：miR-204作用下调与主动脉瓣钙化密切相关，可作为研究主动脉瓣钙化发病机制的重要靶点，但具体调控机制仍有待进一步阐明。最新研究表明：长链非编码RNA（lncRNA）能以竞争性内源RNA的形式抑制miRNA。生物信息学软件分析显示lncRNA MALAT1具有miR-204的结合位点，miR-204能靶向抑制Smad4。我们初步发现：在诱导钙化的瓣膜间质细胞中MALAT1表达显著升高，过表达MALAT1可进一步下调miR-204表达，miR-204受到抑制后，Smad4蛋白表达可上调。本课题拟在此基础上，检测MALAT1、miR-204及Smad4 在主动脉瓣钙化中的表达相关性；在细胞和动物水平，观测MALAT1/miR-204/Smad4信号通路在介导间质细胞成骨分化诱导主动脉瓣钙化中的作用，为主动脉瓣钙化的防治提供新靶点。

主动脉瓣钙化发病率逐年增高，严重危害人类健康。我们前期工作发现:miR-204作用下 调与主动脉瓣钙化密切相关，可作为研究主动脉瓣钙化发病机制的重要靶点，但具体调控机制，仍有待进一步阐明。最新研究表明:长链非编码RNA(lncRNA)能以竞争性内源RNA(ceRNA)的形式抑制 miRNA。本课题组前期研究率先证实：miR-204在主动脉瓣钙化表达显著下调；miR-204可以同时靶向抑制成骨分化特异性转录因子Runx2和共同调节型Smad蛋白Smad4表达；细胞和动物实验表明，上调miR-204表达水平能够显著抑制VICs细胞成骨分化、降低小鼠主动脉瓣钙化程度。本课题组前期研究首次证实，主动脉瓣钙化中存在ceRNA调控机制；lncRNA MALAT1和TUG1均可作为ceRNA与miR-204结合，从而抑制miR-204的表达，导致下游靶基因Runx2和Smad4表达增加。以上结果明确了lncRNA TUG1、MALAT1及miR-204可作为研究主动脉瓣钙化发病机制及治疗策略的重要靶点，ceRNA调控网络在主动脉瓣钙化中发挥重要作用。