目的阐明压力负荷诱导的大鼠心脏松弛素受体(relaxin/insulin like family peptide receptor,RXFP1)表达下调的意义及机制。方法利用大鼠主动脉弓结扎(transvers aorta constriction,TAC)方法建立压力负荷模型,Western Blot检测RXFP1表达水平,并检测siRNA敲减RXFP1的乳大鼠成纤维细胞在松弛素作用下胶原的分泌水平。进一步采用Western Blot检测不同浓度TGFβ1孵育乳大鼠心脏成纤维细胞RXFP1的表达变化。结果 TAC组心脏松弛素受体RXFP1表达下调,敲减RXFP1后松弛素抑制乳大鼠心脏成纤维细胞胶原分泌的作用显著减弱,TGFβ1呈剂量依赖性地下调乳大鼠心脏成纤维细胞RXFP1表达。结论在压力负荷诱导的心室重塑模型中,TGFβ1介导了心脏RXFP1下调,并抑制松弛素发挥抗纤维化作用。
Although microRNAs(miRNAs) have been intensively studied in cardiac fibrosis,their roles in drug-mediated anti-fibrotic therapy are still unknown.Previously,Pioglitazone attenuated cardiac fibrosis and increased miR-711 experimentally.We aimed to explore the role and mechanism of miR-711 in pioglitazone-treated myocardial infarction in rats.Our results showed that pioglitazone significantly reduced collagen-I levels and increased miR-711 expression in myocardial infarction heart.Pioglitazone increased the expression of miR-711 in cardiac fibroblasts,and overexpression of miR-711 suppressed collagen-I levels in angiotensin II(Ang II)-treated or untreated cells.Transfection with antagomir-711 correspondingly abolished the pioglitazone-induced reduction in collagen-I levels.Bioinformatics analysis identified SP1,which directly promotes collagen-I synthesis,as the putative target of miR-711.This was confirmed by luciferase assay and western blot analysis.Additionally,increased SP1 expression was attenuated by pioglitazone in myocardial infarction heart.Furthermore,transfection of antagomir-711 attenuated pioglitazone-reduced SP1 expression in cardiac fibroblasts with or without Ang II stimulation.We conclude that pioglitazone up-regulated miR-711 to reduce collagen-I levels in rats with myocardial infarction.The miR-711-SP1-collagen-I pathway may be involved in the anti-fibrotic effects of pioglitazone.Our findings may provide new strategies for miRNA-based anti-fibrotic drug research.
