MiR-125b-5p regulates cardiomyocyte apoptosis in heart failure model by targeting CACNB1: a mechanistic study

Abstract

Objective To investigate the effect of miR-125b-5p on the apoptosis of cardiomyocytes in heart failure and its potential mechanism. Methods Rat primary cardiomyocytes were isolated and cultured to establish heart failure model induced by 0.8% pentobarbital sodium. Real-time quantitative PCR (qRT-PCR) and Western blotting were used to determine the protein expression of miR-125b-5p and voltage-dependent calcium channel β1 (CACNB1) in cardiomyocytes of heart failure model, respectively. After down-regulation of miR-125b-5p or overexpression of CACNB1, the apoptosis was examined by flow cytometry. The targeting relationship between miR-125b-5p and CACNB1 was verified by Targetscan online prediction, dual luciferase reporter gene assay and Western blotting. The miR-125b-5p inhibitors and CACNB1 siRNA were co-transfected into heart failure cardiomyocytes, and the apoptosis was determined by flow cytometry. Results Compared with the control group, the expression level of miR-125b-5p was up-regulated in heart failure cardiomyocytes (3.11±0.12 vs. 1.04±0.09, P<0.05) , while the mRNA and protein expression levels of CACNB1 were significantly down-regulated (0.76±0.07 vs. 1.96±0.11, 0.53±0.05 vs. 0.94±0.06, both P<0.05) . After down-regulation of miR-125b-5p or overexpression of CACNB1, the apoptosis rate of heart failure cardiomyocytes decreased significantly[ (10.11±0.92) % vs. (19.76±1.07) %, (8.11±0.67) % vs. (21.76±1.22) %, both P<0.05]. The findings of Targetscan online prediction, dual luciferase reporter gene assay and Western blotting indicted that miR-125b-5p could target-regulate the protein expression of CACNB1. Knockdown of CACNB1 could reverse the inhibition of miR-125b-5p on cardiomyocyte apoptosis in heart failure. Conclusion miR-125b-5p may inhibit the apoptosis of cardiomyocytes in rats with heart failure by target-regulation of CACNB1 expression. Key words: miR-125b-5p; Voltage-dependent calcium channel β1 protein; Heart failure; Apoptosis