Abstract 77: 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 cardiac fibrosis. Finally, miR-125b was successfully inhibited in vivo by the systemic delivery of locked nucleic acid (LNA) targeted against miR-125b both in the presence and absence of Angiotensin II (Ang II). These results demonstrated that LNA-125b protected against Ang II-induced proliferation and fibrosis in the mouse heart in vivo. We conclude that TGF-β-induced miR-125b is an important regulator of both fibroblast proliferation and FMT, and miR-125b inhibits key anti-fibrotic mediators to promote cardiac fibrosis. We propose that miR-125b may serve as a novel therapeutic target for the preventative therapy for fibrosis.
Author Disclosures: V. Nagpal: 2. Research Grant; Significant; AHA predocotoral. R. Rai: None. A.T. Place: None. A.K. Ghosh: None. D.E. Vaughan: None.
This research has received full or partial funding support from the American Heart Association, Midwest Affiliate (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota & Wisconsin).
- © 2015 by American Heart Association, Inc.