Abstract: Objective This study was aimed to explore the expression of transcription co-repressor Ski-related protein N(SnoN) and Smad2/3 in renal tissues of diabetic rats, and to investigate their contribution to the fibrosis of renal tubule-interstitium in diabetic rats. Methods The rat model of diabetes was induced by vena caudalis injection of streptozotocin (STZ). Rats in different groups were killed at 2, 4, 8, 12,16 and 24 week of experiments. Meanwhile, the rats were in age-matched as normal control(n=6). The protein or mRNA levels of SnoN, TGF-β1, Smad2/3, α-SMA and fibronectin( FN) in renal tissues were detected. Blood glucose, serum creatinine and 24h urine protein were examined by biochemistry methods. Results The renal SnoN protein level was significant decrease from DM4 weeks(P < 0.01). However, the SnoN mRNA levels were unchanged in each diabetes group, The protein levels of TGF-β1, Smad2/3 and FN were significantly up-regulated in diabetes rats, in diabetes rats, α-SMA tubules staining was seen from 12th week. Conclusion These results showed that SnoN and TGF-β1/Smad signaling pathway may play a key role in the pathogenesis of diabetic nephropathy.

Key words: Ski-related novel protein N, Transforming growth factor-β1, Smad2/3, Diabetic nephropathy, Rat