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.
- 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.
Leave a Reply