Nuclear m6A Methylase METTL3 Drives Production of ITGβ4E to Exacerbate Heart Failure via SRSF3-Mediated Alternative Splicing of ITGβ4.

Heart failure (HF) is an important cause of morbidity and mortality worldwide. Here, we aimed to screen potent regulators in HF progression to assist clinicians in the early diagnosis and management of HF patients. The data were downloaded from the GSE71216, GSE12546, GSE121893, and GSE19303 datasets, and the overlapping downregulated differentially expressed gene (DEG) Integrin β4 (ITGB4) was screened as a key regulator of HF progression. Next, a rat HF model and a cell model of hypoxia-treated cardiomyocytes were constructed, and results showed that ITGB4 was lowly expressed in cardiac tissues of HF rats and hypoxia-treated cardiomyocytes, while ITGB4E, a splice transcript, was highly expressed. Either overexpression of ITGB4 or silencing ITGB4E promoted cell proliferation and invasion and inhibited apoptosis in hypoxia-induced cardiomyocytes. Mechanistic studies showed that METTL3 promoted m6A modification of ITGB4 mRNA, and YTHDC1 bound to m6A-modified ITGB4 mRNA and recruited SRSF3 to splice ITGB4 mRNA, which upregulated ITGB4E mRNA levels. ITGB4E overexpression counteracted cardiomyocyte proliferation and invasion under hypoxia induced by YTHDC1 silencing or SRSF3 silencing. Finally, AAV9 viral plasmids of ITGB4 overexpression vectors and sh-ITGB4E were injected into HF rats, and the results showed that either overexpression of ITGB4 or knockdown of ITGB4E decreased infarct sizes and improved cardiac function in HF rats. Taken together, the m6A methylase METTL3 drives production of ITGβ4E to exacerbate HF via SRSF3-mediated alternative splicing of ITGβ4 mRNA, suggesting that alternative splicing of ITGβ4 may be a potential therapeutic target for HF.