Inhibition of myocyte-specific enhancer factor 2A (MEF2A) attenuates cardiac fibrosis and improves heart function by regulating the Snail1/RhoA/α-SMA pathway.

Myocardial fibrosis (MF) is a key pathological process driving heart failure, characterized by excessive extracellular matrix (ECM) deposition and impaired cardiac function. Although myocyte-specific enhancer factor 2 A (MEF2A) is implicated in cardiac fibroblast activation, its role in MF remains unclear. We manipulated MEF2A expression in cardiac fibroblasts (CFs) through knockdown and overexpression, and assessed fibrosis markers, migration, and RhoA signaling. Binding of MEF2A to the Snail1 promoter was predicted using JASPAR and validated by chromatin immunoprecipitation (ChIP) and luciferase reporter assays. Rescue experiments with Snail1 overexpression and RhoA inhibition were performed. An angiotensin II (Ang II)-induced MF mouse model was used to evaluate cardiac function by echocardiography and to assess collagen deposition through picrosirius red (PSR) staining. MEF2A was significantly upregulated in Ang II-induced fibrotic hearts and CFs. MEF2A knockdown reduced α-SMA and Col1a1 expression, inhibited CF migration, and suppressed activation of the Snail1/RhoA/α-SMA pathway. ChIP and luciferase assays confirmed the direct binding of MEF2A to the Snail1 promoter. Inhibition of RhoA signaling reversed MEF2A-induced myofibroblast activation and migration. Rescue experiments showed that Snail1 overexpression restored the fibrotic phenotype suppressed by MEF2A knockdown. In vivo, MEF2A knockdown improved left ventricular function, reduced collagen deposition (PSR staining), and lowered heart weight/tibia length ratios. MEF2A promotes myocardial fibrosis by directly activating Snail1 and engages the RhoA/α-SMA pathway. Targeting MEF2A offers a promising therapeutic strategy to attenuate MF and improve heart function.