ALYREF stabilizes MZF1 via m5C modification to exacerbate cardiac remodeling and atrial fibrillation in heart failure

Background: Patients with heart failure (HF) frequently develop atrial fibrillation, but the precise molecular mechanisms are unclear, leading to limited therapeutic strategies. Methods: Isoproterenol hydrochloride (ISO)-induced mouse HF model and ISO-treated HL-1 cardiomyocyte model were employed. A combination of qRT-PCR, Western blot, ChIP, dual-luciferase reporter assay, MeRIP-qPCR, RIP-qPCR, actinomycin D assay, and mitochondrial function assessments were used to systematically investigate the regulatory mechanism of the ALYREF/MZF1/HTRA1 axis and its role in cardiac remodeling and atrial fibrillation susceptibility. Results: HTRA1 expression was elevated in HF mice and human atrial fibrillation data. In cellular models, HTRA1 overexpression induced mitochondrial damage, cellular hypertrophy, and inflammation via the HIF-1α pathway. The transcription factor MZF1 directly bound to and activated the HTRA1 promoter. NSUN2-mediated m5C modification of MZF1 mRNA was required for its recognition and stabilization by the m5C reader protein ALYREF, thereby positively regulating the MZF1/HTRA1 axis. In the ISO-induced HF mouse model, knockdown of ALYREF effectively reduced MZF1 and HTRA1 expression, alleviated myocardial hypertrophy, fibrosis, cardiac dysfunction, and atrial fibrillation inducibility. Conclusion: This study elucidates a novel signaling axis wherein NSUN2-mediated m5C modification of MZF1 mRNA enables its stabilization by ALYREF, leading to transcriptional upregulation of HTRA1. This axis drives cardiomyocyte mitochondrial dysfunction, hypertrophy, and inflammation in the context of HF, ultimately increasing susceptibility to atrial fibrillation.