Abstract 370: MicroRNA-19b Contributes to Cardiac Fibrosis

Abstract

Fibrosis is one of the most important characteristics of cardiac remodeling during heart failure. The accumulation of extracellular matrix (ECM) within myocardium is the major feature of cardiac fibrosis. microRNA (miR)-19b, a key functional member of miR-19-72 cluster family, has been suggested to be involved in aging-induced heart failure through regulating ECM-related proteins, such as connective tissue growth factor (CTGF), thrombospondin-1 (TSP-1), collagen-1A1, and collagen-3A1. In the current study, we aimed to investigate the role of miR-19b in cardiac fibroblast function and ECM production using neonatal rat cardiac fibroblasts in primary culture. We found that overexpression of miR-19b increased, while inhibition of miR-19b decreased the proliferation and migration of cardiac fibroblasts, using Cell Counting Kit-8 (CCK-8) (0.660±0.019 vs 0.720±0.014 in nc-mimic and miR-19b mimic, 0.506±0.009 vs 0.454±0.008 in nc-inhibitor and miR-19b inhibitor, respectively), EdU incorporation assay (0.059±0.002 vs 0.096±0.006 in nc-mimic and miR-19b mimic, 0.059±0.006 vs 0.040±0.003 in nc-inhibitor and miR-19b inhibitor, respectively), and wound healing assay (0.528±0.024 vs 0.896±0.027 in nc-mimic and miR-19b mimic,0.520±0.028 vs 0.174±0.019 in nc-inhibitor and miR-19b inhibitor, respectively), respectively. Meanwhile, the inhibition of miR-19b downregulated the mRNA levels of α-SMA (0.556±0.048 vs 1.038±0.137 in nc-inhibitor and miR-19b inhibitor, respectively) and collagen-1 (1.023±0.116 vs 0.551±0.033 in nc-inhibitor and miR-19b inhibitor, respectively) in cardiac fibroblasts, indicating a reduction in fibroblast activation and ECM production via miR-19b inhibition. Furthermore, we found that PTEN was negatively regulated by miR-19b in cardiac fibroblasts using western blot analysis. PTEN, a well-known tumor-suppressor gene, has been known to inhibit cell proliferation and migration. However, it remains to be further clarified whether PTEN could mediate the effect of miR-19b in the proliferation, migration and activation of fibroblasts. These data might provide important evidence suggesting that miR-19b could be a potential therapeutic target for cardiac fibrosis.