P300-mediated H3K18 acetylation triggers necroptosis via modulation of KRT18 transcription in diabetic nephropathy

Diabetic nephropathy (DN) is a major cause of end-stage renal disease. While glomerular damage is a known aspect of its pathology, tubular epithelial cell necroptosis also plays a crucial role in disease progression. Epigenetic modifications, particularly histone acetylation, have garnered attention for their role in the regulation of kidney damage-related gene expression. This study explores whether the histone acetyltransferase P300 regulates KRT18 expression via histone H3 lysine 18 acetylation (H3K18ac), driving tubular epithelial cell necroptosis and accelerating DN progression. We establish an STZ-induced diabetic nephropathy mouse model and a high glucose-treated HK-2 cell model. Western blot analysis, qPCR, immunohistochemistry, and AO/PI staining are employed to assess the expression levels of P300, H3K18ac, KRT18, and necroptosis-related proteins (RIPK1 and MLKL). Functional validation of the P300-KRT18 axis is performed using shRNA interference, overexpression, and the small molecule inhibitor C646. Both in vivo and in vitro models show significant upregulation of P300, H3K18ac, and KRT18, coupled with RIPK1/MLKL pathway activation and increased cell death. P300 knockdown or C646 treatment effectively inhibits H3K18ac and KRT18 expression, reducing necroptosis; KRT18 knockdown also alleviates P300 overexpression-induced cell death. Co-transfection with P300 overexpression and KRT18 interference demonstrates that KRT18 is a key downstream effector of P300-mediated necroptosis. In conclusion, P300 upregulates KRT18 expression through H3K18 acetylation, subsequently activating the RIPK1/MLKL pathway and promoting tubular epithelial cell necroptosis. The P300-KRT18 axis may serve as a novel epigenetic therapeutic target for DN, suggesting that epigenetic regulation could be a viable intervention strategy to delay DN progression.