Paper Title
MIR-195-3P Promotes Cardiac Fibrosis after Myocardial Infarction via Modulation of PTEN

Background: Dysregulation of microRNAs is strongly linked to the development of cardiac fibrosis. miR-195-3p is up-regulated in a wide range of fibrotic diseases, including cardiac fibrosis; however, its role and mechanisms in cardiac fibrosis are still unclear. Methods: 8 weeks-old C57B/L6 mice underwent LAD ligation and were injected with anti-miR-195-3p to knockdown cardiac miR-195-3p expression in mice. Neonatal mouse cardiac fibroblasts were treated with TGF-β1 to induce fibrosis in vitro and with miR-195-3p mimic and inhibitor to up- or downregulate miR-195-3p expression. Results: miR-195-3p increased significantly in response to LAD ligation. Just 2 days after LAD ligation, miR-195-3p expression in the ventricles of MI mice increased 3.17-fold. anti-miR-195-3p delivery decreased ventricular expression of miR-195-3p, reduced the expression of hypertrophic gene markers ANP, BNP, β-MHC and the expression of Collagen I, Collagen III and FN1 and alleviated the MI-induced cardiac dysfunction. Inhibition miR-195-3p significantly decreased LV fibrosis and remote area fibrosis in MI mice. Immunohistochemistry showed that miR-195-3p inhibition attenuated the differentiation of CFs into myofibroblasts while overexpression of mir-195-3p in CFs and TGF-β1 treatment increased miR-195-3p expression, increased the expression of profibrotic genes, promoted myofibroblasts differentiation and enhanced CFs migration and proliferation. Furthermore, miR-195-3p overexpression increased FN1 and Collagen I protein expression while miR-195-3p inhibition lessened the TGF-β1-induced enhancement of Collagen I and Collagen III expression. miR-195-3p mimic reduced PTEN gene and protein expression. miR-195-3p overexpression in CF induced AKT phosphorylation while the knockdown by miR-195-3p inhibitor counteracted AKT phosphorylation. Conclusion: miR-195-3p modulates cardiac fibrosis by activating the PI3K/AKT signaling pathway via knockdown of PTEN expression. Inhibition of miR-195-3p could be a potential therapeutic target to counteract cardiac fibrosis after MI.