Divergent splicing factor SRSF1 signaling promotes inflammation post-CME: the SRSF1/ENPP3 axis acts via inhibition of BRD4 O-GlcNAcylation to enhance NF-κB activation and accelerate heart failure.

Abstract

Rationale: Coronary microembolization (CME) is a severe medical condition that occurs during acute coronary syndrome, leading to myocardial inflammation, apoptosis, and cardiac dysfunction. The research investigated SRSF1 biological functions during myocardial inflammation caused by CME and its underlying mechanisms. Methods: CME models were established in rats injected with microspheres in the left ventricle and oxygen-glucose deprivation (OGD)-exposed cardiomyocytes. RT-qPCR, Western blotting and immunohistochemical staining were used to evaluate the expression of target molecules. Myocardial apoptosis was detected by flow cytometry. The direct binding between SRSF1 and ectonucleotide pyrophosphatase/phosphodiesterase 3 (ENPP3) was verified by RIP and TRAP. Protein interaction was determined by Co-IP. The dual-luciferase reporter assay measured inflammatory cytokine transcription levels. Myocardial injury was assessed by HE staining and ultrasound examinations. The study used ELISA to measure inflammatory cytokines and cardiac troponin I (cTnI) levels. Results: SRSF1 expression was strikingly enhanced in CME models. Knockdown of SRSF1 effectively restrained NF-κB-mediated myocardial inflammation through increasing ENPP3 mRNA/lncRNA ENPP3 ratio by regulating alternative splicing of ENPP3 pre-mRNA. The GlcNAcylation of bromodomain-containing protein 4 (BRD4) was reduced during CME, which increased BRD4 protein level to trigger NF-κB-mediated inflammation. SRSF1/ENPP3 axis inhibited the GlcNAcylation of BRD4 in CME. Myocardial-specific knockout of SRSF1 restored cardiac function and restrained myocardial inflammation in CME rats by inactivation of the ENPP3/BRD4/NF-κB pathway. Conclusions: SRSF1 facilitates CME-induced myocardial inflammation by up-regulating ENPP3/lncRNA ENPP3 ratio to suppress GlcNAcylation of BRD4, suggesting SRSF1 inhibition as a promising therapeutic strategy for CME.