Abstract / Summary
Diabetic kidney disease (DKD) is characterized by tubular metabolic remodeling, inflammation, and profibrotic injury. However, whether integrin β2 (ITGB2) links high-glucose (HG) stress to hypoxia-inducible factor-1α (HIF-1α)/glucose transporter 1 (GLUT1)-dependent metabolic reprogramming in renal tubular epithelial cells remains unclear. This study investigated the role and underlying mechanism of the ITGB2/HIF-1α/GLUT1 axis in HG-induced tubular injury. ITGB2 expression was first examined in the publicly available human renal transcriptomic dataset GSE30529. HK-2 cells were cultured under normal-glucose, HG, or mannitol osmotic-control conditions. ITGB2 was silenced or overexpressed, and HIF1A or SLC2A1/GLUT1 was knocked down by siRNA. Protein expression, HIF-1α nuclear accumulation, and HIF-1α protein stability were assessed by western blotting, subcellular fractionation, and cycloheximide-chase assays. Metabolic remodeling was evaluated by 2-NBDG uptake, lactate production, extracellular acidification rate (ECAR), oxygen consumption rate (OCR), and ATP content. Tubular injury, inflammatory, and EMT-like/profibrotic phenotypes were assessed by ELISA and RT-qPCR. Dual-luciferase reporter and chromatin immunoprecipitation assays were performed to evaluate HIF-1α-mediated transcriptional regulation of GLUT1. ITGB2 expression was increased in the tubulointerstitial compartment of human diabetic kidneys in GSE30529. In HK-2 cells, HG increased ITGB2, HIF-1α, and GLUT1 expression, accompanied by increased glucose uptake, lactate production, ECAR, and ATP content and reduced OCR, together with enhanced tubular injury, inflammatory, and EMT-like/profibrotic responses. ITGB2 knockdown reduced HIF-1α/GLUT1 expression and nuclear HIF-1α accumulation and accelerated HIF-1α protein decay, suggesting that ITGB2 contributes to HIF-1α protein stability. HIF-1α directly bound to and transcriptionally activated the GLUT1 promoter. ITGB2 overexpression further enhanced metabolic reprogramming and pathological phenotypes, whereas HIF1A or SLC2A1 silencing markedly attenuated these effects. ITGB2 promotes HIF-1α/GLUT1-dependent metabolic reprogramming and contributes to tubular injury, inflammatory, and EMT-like/profibrotic responses in HG-treated HK-2 cells. These findings support a role for the ITGB2/HIF-1α/GLUT1 signaling axis in coordinating metabolic and pathological responses under HG conditions.