Histone lactylation mediates the USP22/HIF-1α positive feedback loop to promote the progression of diabetic...

This study aims to investigate the role and molecular mechanism of USP22 in diabetic retinopathy (DR), focusing on its regulation by histone lactylation and a positive feedback loop with HIF-1α.

A DR mouse model was established via intraperitoneal injection of STZ, and in vitro DR models were induced using high glucose (HG) treatment in ARPE-19 and mRPE. Cell damage was assessed through CCK-8, EdU staining, and other experiments, while retinal damage was evaluated via H&E staining and TUNEL staining.

In DR models both in vivo and in vitro, USP22 expression was significantly elevated. Knockdown of USP22 alleviated retinal damage in DR mice and reduced injury in ARPE-19 and mRPE cells exposed to HG, an effect associated with suppressed glycolysis. HIF-1α was also upregulated in DR. Co-IP assays confirmed that USP22 stabilizes HIF-1α through deubiquitination. Overexpression of HIF-1α partially reversed the inhibitory effects of USP22 knockdown on glycolysis and cellular damage under HG conditions. Furthermore, ChIP analysis revealed that lactate, a glycolytic product, promotes USP22 transcription and expression via H3K18la modification, forming a glycolysis/H3K18la/USP22/HIF-1α positive feedback loop. HIF-1α overexpression reversed the glycolysis inhibitor 2-DG-induced suppression of USP22 H3K18la modification and expression in HG-exposed cells, while attenuating the protective effect of 2-DG against cellular injury. Consistently, in vivo, knockdown of USP22/HIF-1α or 2-DG treatment downregulated USP22, Pan Kla, and H3K18la in DR retinas, while ameliorating retinal structural damage and apoptosis.

Our study reveals that a "glycolysis/H3K18la/USP22/HIF-1α" positive feedback loop exists in DR, promoting disease progression.