Inhibition of Setd7 protects against cardiomyocyte hypertrophy via inhibiting lipid oxidation.

Myocardial hypertrophy is one of the most prominent features of heart failure. SET domain-containing protein 7 (Setd7), a catalytic enzyme responsible for histone H3K4 methylation, has been implicated in various cardiac diseases. In this study we investigated whether Setd7 contributed to the development of cardiac hypertrophy. Male mice were subjected to a hypobaric hypoxic environment for 8 weeks; neonatal rat cardiomyocytes (NRCMs) exposed to hypoxia for 6 h. We showed that hypoxic stimulation significantly upregulated the expression levels of Setd7 along with the expression of hypertrophic markers ANP and BNP in NRCMs. By conducting loss- and gain-of-function assays, we demonstrated that Setd7 modulated the hypertrophic and inflammatory markers in hypoxic cardiomyocytes. We further revealed that Setd7-mediated activation of E2F1 (E2 promoter binding factor 1) triggered the expression of E3 ubiquitin protein ligases WWP2, which catalyzed the ubiquitination and degradation of glutathione peroxidase 4 (GPx4), a critical lipid peroxide-reducing enzyme. This degradation drove extensive lipid peroxidation, thereby exacerbating pathological cardiac hypertrophy. Notably, GPx4 inhibition by ras-selective lethal small molecule 3 (RSL3) abolished the antihypertrophic effects of Setd7 knockdown in cardiomyocytes, underscoring the pivotal role of lipid peroxidation in Setd7-mediated hypertrophic responses. In summary, Setd7 promotes hypoxia-induced cardiac hypertrophy through the Setd7-E2F1-WWP2-GPx4 signaling pathway, suggesting that targeting Setd7 is a promising therapeutic strategy to alleviate hypoxia-induced myocardial hypertrophy.