Set7 regulates ferroptosis in pulmonary arterial hypertension endothelial cells through the DPP4/NOX4 axis mediated...

Dipeptidyl peptidase-4 (DPP4)-targeted therapy is widely employed in the therapy of pulmonary diseases, but the role of its H3K4me1 modification in pulmonary arterial hypertension (PAH) disease remains unknown. This study aims to investigate the function of histone methyltransferase SET domain containing 7 (Set7)-mediated monomethylation of histone 3 lysine 4 (H3K4me1) modification of DPP4 in PAH, with the goal of providing new insights for the broader application of DPP4-targeted therapies.

The PAH mouse model was constructed and intervened with overexpression (oe) or knockdown (sh) of DPP4, sh-Set7, oe-NADPH oxidase 4 (NOX4) or sh-Set7 + erastin. Human pulmonary arterial endothelial cells were induced by hypoxia and treated with sh-DPP4, erastin, oe-DPP4, sh-Set7, oe-NOX4, oe-Set7 or oe-Set7 + ferrostatin-1. The enrichment of H3K4me1 level in the DPP4 promoter region was analyzed by ChIP and dual-luciferase assay. Pulmonary vascular remodeling, fibrosis, and endothelial injury were observed by echocardiography, HE, MASSON, and α-SMA staining. Ferroptosis markers and protein expression were measured using biochemical assay kits, RT-qPCR, WB, immunofluorescence, and transmission electron microscopy.

Silencing DPP4 alleviates pulmonary vascular remodeling, fibrosis, and endothelial injury in PAH mice, reduces cardiac fibrosis and pulmonary inflammation, while improving mitochondrial damage in the lungs and downregulating the level of ferroptosis-related proteins. ChIP assays confirmed increased enrichment of H3K4me1 in the DPP4 promoter region in both hypoxia-induced endothelial cells and lung tissues of PAH mice. Overexpression of Set7 resulted in elevated H3K4me1 enrichment in the DPP4 promoter region and increased NOX4 protein expression. Ferrostatin-1 inhibited the promotion of oe-Set7 in hypoxia-induced endothelial cell injury. Silencing Set7 mitigated hypoxia-induced endothelial cell injury, ferroptosis, and inflammatory responses by downregulating DPP4/NOX4. Erastin reversed the treatment effect of sh-Set7 in PAH mice. Furthermore, Set7 knockdown ameliorated PAH in mice by suppressing DPP4/NOX4-mediated ferroptosis.

The H3K4me1 modification of DPP4 is upregulated in PAH, a process regulated by Set7. Silencing Set7 alleviates PAH by suppressing ferroptosis through the DPP4/NOX4 signaling pathway, offering a novel gene therapy approach for this disease.