MiR-125b Regulates Myofibroblast Transition and Cardiac Fibrosis

Transforming growth factor-β (TGF-β)-induced fibroblast-to-myofibroblast transition (FMT) is a critical determinant of cardiac fibrosis. However, the contribution of microRNAs leading to TGF-β-induced FMT and cardiac fibrosis are not well-understood. Our results elucidate that blocking the canonical TGF-β pathway protects from FMT in primary cultures of human cardiac fibroblasts and that miR-125b is significantly upregulated during cardiac FMT. Furthermore, we observed significant upregulation of miR-125b in fibrotic human myocardium and two murine models of cardiac fibrosis. Importantly, we discovered that miR-125b is sufficient to induce cardiac FMT. In contrast, the knockdown of miR-125b using an antagomir approach attenuated TGF-β-induced FMT. In silico analysis and biochemical analysis revealed that miR-125b directly targets multiple anti-fibrotic mediators including p53 and apelin. In addition, miR-125b also plays a potent role in the regulation of fibroblast proliferation, an important cause of car...