ALKBH5 promotes cardiac fibroblasts pyroptosis after myocardial infarction through Notch1/NLRP3 pathway.

Through bioinformatics screening, we previously found that AlkB homolog 5 (ALKBH5) expression, an mA demethylase, was higher in patients with heart failure than in the normal population. This study aimed to investigate the molecular mechanisms by which ALKBH5 regulates heart failure. We established a myocardial infarction (MI)-induced heart failure model in rats in vivo and an in vitro hypoxia model using rat primary cardiac fibroblasts (RCFs). MA sequencing, RNA immunoprecipitation assay, RNA pull-down assay, proximity ligation assay, gain-of-function and loss-of-function experiments, and transcriptomic analysis were performed to confirm the pyroptosis-promoting effects of ALKBH5. The effects of two small-molecule inhibitors (ZINC78774792 and ZINC00546946) on ALKBH5 expression were examined. The expression of mA demethyltransferase ALKBH5 was significantly elevated in hypoxia-induced RCFs. Transcriptional profiling revealed Notch receptor 1 (Notch1) as an mA modification target of ALKBH5, and Notch1 mRNA mA modifications were increased in ALKBH5-deficient RCFs. Moreover, Notch1 and NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) are associated. ALKBH5 knockdown alleviated hypoxia-induced RCF cell pyroptosis by inhibiting Notch1, NLRP3 inflammasome activation, and pyroptosis-associated protein (N-GSDMD), whereas ALKBH5 overexpression had the opposite effect. Targeting ALKBH5 with two small-molecule inhibitors (ZINC78774792 and ZINC00546946) reduced hypoxia-induced RCF pyroptosis, and ZINC00546946 alleviated cell pyroptosis after myocardial infarction in mice. Our results indicate that ALKBH5 promotes cardiac fibroblast pyroptosis after myocardial infarction through the Notch1/NLRP3 pathway. Therefore, inhibiting ALKBH5 may be a strategy for treating cardiovascular diseases.