Underexpression of CACNA1C Caused by Overexpression of microRNA-29a Underlies the Pathogenesis of Atrial Fibrillation

BACKGROUND: The objective of this study was to investigate the molecular mechanism of atrial fibrillation (AF), as well as the negative regulatory relationship between miR-29a-3p and CACNA1C. MATERIAL/METHODS: We searched the online miRNA database (www.mirdb.org) and identified the miR-29a-3p binding sequence within the 3′-UTR of the target gene, and then conducted luciferase assay to verify it. The cells were transfected with miR-29a-3p and I(Ca,L) was determined in those cells. RESULTS: We validated CACNA1C to be the direct target gene of miR-29a-3p. We also established the negative regulatory relationship between miR-29a-3p and CACNA1C via studying the relative luciferase activity. We also conducted real-time PCR and Western blot analysis to study the mRNA and protein expression level of CACNA1C among different groups of cells treated with scramble control, 30nM miR-29a-3p mimics, and 60nM miR-29a-3p mimics, indicating a negative regulatory relationship between miR-29a-3p and CACNA1C. We next analyzed whether miR-29a-3p transfection in cardiomyocytes produced the effects on the I(Ca,L) induced by electrical remodeling, and found a tonic inhibition of I(Ba) by endogenous miR-29a-3p in atrial myocytes. CONCLUSIONS: We validated the negative regulation between miR-29a-3p and CACNA1C, and found that miR-29a-3p might a potential therapeutic target in the treatment of AF.