O-GlcNAcylation Stabilizes NEK7 to Drive Podocyte Pyroptosis in Diabetic Kidney Disease

Diabetic kidney disease (DKD) progression involves NIMA-related kinase 7 (NEK7)-driven podocyte pyroptosis, with hyperglycemia-induced O-GlcNAcylation as a key posttranslational regulator. This study elucidates how O-GlcNAc modification governs NEK7 stability and its pathological role. We used clinical DKD specimens, high-glucose-stimulated podocytes, and streptozotocin-induced diabetic mice to first examine NEK7, O-GlcNAc, O-GlcNAc transferase (OGT), and glutamine fructose-6-phosphate amidotransferase 1 (GFPT1) expression, confirming the pyroptosis role of NEK7 via siRNA knockdown. Bioinformatic analysis predicted O-GlcNAcylation motifs, validated by T302A mutagenesis and coimmunoprecipitation. Protein stability was assessed using cycloheximide chase and ubiquitination assays. Therapeutic efficacy of the GFPT1 inhibitor (6-diazo-5-oxo-l-norleucine) DON was evaluated in vitro and in vivo through biochemical parameters, histopathology, and pyroptosis markers. Chronic hyperglycemia activated the hexosamine biosynthetic pathway (HBP), elevating pathology-associated O-GlcNAc modifications that promoted NEK7 accumulation via posttranslational stabilization. This was accompanied by upregulated O-GlcNAc, OGT, and GFPT1 in DKD glomeruli and high-glucose podocytes. Crucially, threonine 302 was identified as the primary O-GlcNAcylation site of NEK7. This modification reduced proteasomal degradation, extended NEK7 half-life, and enhanced NLRP3 inflammasome activation and interleukin release. Pharmacological HBP inhibition using DON normalized O-GlcNAcylation, suppressed pyroptosis, and mitigated renal injury. We report the discovery of the glucose/O-GlcNAc/NEK7/NLRP3 axis driving podocyte pyroptosis in DKD, proposing threonine 302 as a potential therapeutic target. These findings establish a novel posttranslational modification mechanism and suggest a dual-target therapeutic strategy for DKD management. ARTICLE HIGHLIGHTS: We identify threonine 302 as the critical O-GlcNAcylation site on NIMA-related kinase 7 (NEK7), which stabilizes NEK7 by inhibiting its proteasomal degradation, thereby enhancing NLRP3 inflammasome activation and podocyte pyroptosis in diabetic kidney disease (DKD). Chronic hyperglycemia activates the hexosamine biosynthetic pathway (HBP), driving pathological O-GlcNAcylation and significant upregulation of NEK7, O-GlcNAc transferase, and glutamine fructose-6-phosphate amidotransferase 1 in glomeruli from patients with DKD and experimental models. This study establishes the discovery of the pathogenic glucose/O-GlcNAc/NEK7/NLRP3 signaling axis, identifying a novel posttranslational mechanism driving podocyte loss in DKD progression. Pharmacological inhibition of the HBP with 6-diazo-5-oxo-l-norleucine normalizes O-GlcNAcylation, suppresses NEK7-driven pyroptosis, and mitigates renal injury, demonstrating the therapeutic potential of targeting threonine 302, NEK7, or the HBP for DKD management.