O-GlcNAcylation regulates HIF-1α and induces mesothelial-mesenchymal transition and fibrosis of human peritoneal mesothelial cells

O-GlcNAcylation is a post-translational modification of proteins that regulates various biological processes. However, its involvement in peritoneal dialysis fibrosis remains unclear. This study aimed to investigate the impact of O-GlcNAcylation on human peritoneal mesothelial cells (HPMCs) cultured in control and high-glucose medium. To manipulate cellular conditions, we employed knockdown techniques targeting HIF-1 alpha and OGT, along with the administration of pharmacological agents (PUGNAc, OSMI-1, MG-132, FG-4592, and HIF-1 alpha inhibitor). Our findings revealed that elevated glucose levels increased global O-GlcNAcylation and the abundance of HIF-1 alpha, alpha-SMA, fibronectin, and COL1A2. Conversely, the expression of E-Cadherin was decreased. Significantly, a positive correlation was observed between O-GlcNAcylation, HIF-1 alpha, mesothelial-to-mesenchymal transition (MMT), and fibrosis in HPMCs. Notably, O-GlcNAcylation was found to regulate HIF-1 alpha, thereby promoting MMT and fibrosis under high glucose conditions. Furthermore, we discovered that high glucose levels induced O-GlcNAcylation of HIF-1 alpha, preventing its ubiquitination and proteasomal degradation. In summary, our study demonstrates the critical role of O-GlcNAcylation-mediated regulation of HIF-1 alpha in MMT and fibrosis during peritoneal dialysis.