<scp>RBM25</scp> Regulates p38 <scp>MAPK</scp> Pathway Activation via Exon 16 Skipping of <scp>MAP4K4</scp> in a Rat Model of Post‐Infarction Heart Failure

Ischemic cardiomyopathy remains a leading cause of heart failure (HF), yet its molecular mechanisms remain incompletely defined. This study aimed to identify the RNA-binding protein 25(RBM25) as a critical regulator of HF progression through MAP4K4 alternative splicing and p38 MAPK pathway activation. A left anterior descending (LAD) coronary artery ligation-induced HF model was established in Sprague-Dawley (SD) rats, with pericardial delivery of lentiviral vectors for RBM25 overexpression (OE-RBM25) or shRNA-mediated knockdown (sh-RBM25). Quantitative PCR (qPCR) experiments confirmed that overexpression of RBM25 induces exon 16 skipping in MAP4K4. Computational modeling further predicted that the resulting variant enhances binding to MAP3K1 and potentially activates the MAPK pathway. Cardiac function, infarct size, apoptosis, and molecular markers were evaluated via echocardiography, TTC staining, ELISA, qPCR, Western blot, and TUNEL assays. RBM25 overexpression significantly increased myocardial infarction area compared to the HF control group (<i>p</i> < 0.01), while RBM25 knockdown reduced infarct size (<i>p</i> < 0.01). Consistently, RBM25 overexpression upregulated pro-apoptotic markers (Caspase-3, Bax; <i>p</i> < 0.05) and downregulated anti-apoptotic Bcl-2 (<i>p</i> < 0.05), whereas RBM25 inhibition reversed these effects. Mechanistically, RBM25 induced exon 16 skipping in MAP4K4, generating a truncated isoform that activated MAPK signaling, as evidenced by increased phosphorylation of ERK (<i>p</i> < 0.05) and elevated downstream effectors (C-FOS, EGR1, PARP1; <i>p</i> < 0.05). P38 MAPK inhibition (SB203580) attenuated RBM25-mediated myocardial injury, while agonist-induced MAPK activation (Gambogic Amide) abolished the protective effects of RBM25 knockdown. These findings suggest that RBM25 exacerbates HF through MAP4K4 splicing-dependent p38 MAPK activation, highlighting its potential as a therapeutic target for ischemic cardiomyopathy.