Gene expression profiling in glomeruli of diabetic nephropathy rat

Diabetic nephropathy (DN) remains the most common cause of end-stage renal disease (ESRD) as the burden of diabetes increases worldwide. To find improved intervention strategies for this disease, it is necessary to investigate the molecular mechanisms involved. To obtain more insight into processes that lead to DN, mRNA expression profiles of diabetic and normal glomeruli from rat kidneys were compared. Rats were divided into a control group and a DN group randomly. The DN group was injected with streptozotocin. Fasting blood glucose (FBG) and weight were measured monthly. On the 12th week, blood samples were collected and analyzed for plasma creatinine and blood urea nitrogen (BUN). Glomeruli were isolated and Illumina Rat Ref-12 V1.0 Expression Beadchip gene array was performed. Quantitative realtime polymerase chain reaction (Q-RT-PCR) was used to confirm the results of gene array for a selected number of genes. We found FBG, 24-h urinary albumin, serum creatinine and BUN were significantly increased, while urinary creatinine and body weight were significantly decreased in the DN group. Glomeruli from the DN group had 624 genes with differential expression. DAVID (Database for Annotation, Visualization and integrated Discovery) analysis showed that the three most enriched terms were 'cytosol' (GO:0005829), 'translational elongation' (GO:0006414) and 'mitochondion' (GO:0005739). Those genes could be mapped to eight pathways. The most common type of enriched pathway was related to 'extracellular matrix (ECM)-receptor interaction'. Other pathways included those for 'ribosome', 'focal adhesion', 'oxidative phosphorylation', 'transforming growth factor (TGF)-beta signaling pathway', 'Parkinson's disease', 'Alzheimer's disease' and 'renin-angiotensin system'. Q-RT-PCR verified that Atp5b (F1-ATPase beta subunit), Col1a1 (collagen type 1 alpha 1), Cox6c (cytochrome c oxidase subunit VIc), Ndufs3 (NADH dehydrogenase [ubiquinone] Fe-S protein 3) and Tgfb1 (transforming growth factor β1) were significantly up-regulated in the DN group. The expressions of NDUFS3 and TGF-β1 in DN rats were increased. Our findings suggested that the oxidative phosphorylation pathway, ECM-receptor interaction, TGF-β pathway and renin-angiotensin system may be involved in the development of DN.