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Updated: Aug 10, 2026
Comparative Proteomic Analysis of Whole Kidney, Medulla, and Cortical Tubules in Diabetic Pathogenesis of Kidney Injury in Mice
Published on: May 2, 2025
Upregulation of osteopontin gene expression in diabetic rat proximal tubular cells revealed by microarray profiling
1Research Centre, Centre hospitalier de l'Université de Montréal-Hôtel-Dieu, Montreal, Quebec, Canada.
Abstract:
Progression of diabetic nephropathy appears directly related to renal tubulointerstitial injury, but the involved genes are incompletely delineated. To identify such genes, DNA microarray analysis was performed with RNA from renal proximal tubules (RPTs) of streptozotocin-induced diabetic Wistar rats, spontaneously diabetic BioBreeding rats, and rat immortalized renal proximal tubular cells (IRPTCs) exposed to high glucose (25 mM) medium for 2 weeks. Osteopontin (OPN) mRNA expression was quantified by real time-quantitative polymerase chain reaction (RT-qPCR) or conventional reverse transcriptase-polymerase chain reaction (RT-PCR). OPN mRNA expression was upregulated (5-70-fold increase) in diabetic rat RPTs and in IRPTCs chronically exposed to high glucose compared to control RPTs and IRPTCs. High glucose, angiotensin II, phorbol 12-myristate 13-acetate and transforming growth factor-beta 1 (TGF-beta1) stimulated OPN mRNA expression in IRPTCs in a dose- and time-dependent manner. This effect was inhibited by tiron, taurine, diphenylene iodinium, losartan, perindopril, calphostin C, or LY 379196 but not PD123319. IRPTCs overexpressing dominant-negative protein kinase C-beta 1 (PKC-beta1) cDNA or antisense TGF-beta1 cDNA prevented the high glucose effect on OPN mRNA expression. We concluded that high glucose-mediated increases in OPN gene expression in diabetic rat RPTs and IRPTCs are mediated, at least in part, via reactive oxygen species generation, intrarenal rennin-angiotensin system activation, TGF-beta1 expression, and PKC-beta1 signaling.
Insights
Diabetic nephropathy progression involves renal tubulointerstitial injury. High glucose increases Osteopontin (OPN) gene expression via reactive oxygen species, renin-angiotensin system, TGF-beta1, and PKC-beta1 signaling.
Area of Science:
- Nephrology
- Molecular Biology
- Biochemistry
Background:
- Diabetic nephropathy is a leading cause of kidney failure.
- Renal tubulointerstitial injury is a key factor in diabetic nephropathy progression.
- The specific genes involved in this injury are not fully understood.
Purpose of the Study:
- To identify genes contributing to renal tubulointerstitial injury in diabetic nephropathy.
- To investigate the role of Osteopontin (OPN) in high glucose-induced kidney damage.
- To elucidate the signaling pathways mediating OPN gene expression in diabetic conditions.
Main Methods:
- DNA microarray analysis of renal proximal tubules (RPTs) from diabetic and control rats.
- Culture of immortalized renal proximal tubular cells (IRPTCs) exposed to high glucose.
- Quantification of OPN mRNA expression using real-time quantitative PCR (RT-qPCR) and reverse transcriptase-PCR (RT-PCR).
- Stimulation of OPN expression with high glucose and other factors, followed by inhibition studies.
Main Results:
- OPN mRNA expression was significantly upregulated in diabetic rat RPTs and high glucose-treated IRPTCs.
- High glucose, angiotensin II, and TGF-beta1 dose- and time-dependently stimulated OPN mRNA expression in IRPTCs.
- Inhibitors of reactive oxygen species, renin-angiotensin system, and PKC-beta1 signaling reduced OPN expression.
- Overexpression of dominant-negative PKC-beta1 or antisense TGF-beta1 prevented high glucose-induced OPN upregulation.
Conclusions:
- High glucose significantly increases Osteopontin (OPN) gene expression in diabetic kidney disease.
- This upregulation is mediated by reactive oxygen species, intrarenal renin-angiotensin system activation, TGF-beta1, and protein kinase C-beta1 (PKC-beta1) signaling.
- OPN may play a crucial role in the tubulointerstitial injury associated with diabetic nephropathy.