锌指转录因子Snail 1在糖尿病大鼠肾组织中的表达

目的： 观察锌指转录因子Snail 1在糖尿病大鼠肾组织中的表达并探讨其与糖尿病肾病（DN）发生、发展的关系。方法: 链脲佐菌素（STZ）诱发大鼠糖尿病（DM），分为2、4、8、12、16、20、24周以及16周A、20周A和24周A组，其中A组动物从第13周起用胰岛素控制血糖至正常水平，每个时点均设鼠龄匹配的正常对照组。测定各组血糖、24 h尿蛋白、血肌酐（Scr）、肾脏指数。PAS染色光镜观察肾脏病理改变。免疫组化、RT-PCR方法检测肾皮质Snail 1和纤连蛋白（FN）的蛋白及mRNA水平，Western blotting检测Snail 1蛋白表达。结果: DM各组大鼠的血糖、24 h尿蛋白、血肌酐、肾脏指数明显高于正常对照组（P<0.05,P<0.01），A组上述指标均明显低于DM组（P<0.05,P<0.01）。Snail 1免疫组化阳性染色见于各组DM大鼠肾小管，正常对照组未见阳性表达，A组见弱阳性表达，并随治疗时间延长而减少。DM组肾皮质Snail 1、FN蛋白和mRNA的表达水平高于正常对照组（P<0.01），而A组显著低于DM组（P<0.01）。Snail 1与FN mRNA的表达水平呈显著正相关（P<0.01），Snail 1蛋白表达水平与血糖、尿蛋白、血肌酐、肾脏指数亦呈正相关（ P<0.01）。结论: Snail 1基因和蛋白在DM大鼠肾组织过度表达，提示Snail 1可能参与了DN的发生、发展机制。

Expression of zinc-finger transcription factor Snail 1 in the kidney of diabetic rats

AIM: To explore the expression of Snail 1 in renal tissues of diabetic rats, and to investigate its contribution to the progression of diabetic nephropathy. METHODS: Streptozotocin-induced diabetic rats were randomly divided into 2, 4, 8, 12, 16, 20, 24 weeks groups and 16 week A, 20 week A and 24 week A groups. A groups were treated with insulin to control blood glucose to normal level from the 13th week. Control groups were set up in age-matched time points. Blood glucose, 24 h urine protein, serum creatinine (Scr) and kidney index of rats were measured. Periodic acid-silver (PAS) staining was used to observe the renal pathological changes. The mRNA and protein expressions of Snail 1 and FN in renal cortex were detected by RT-PCR and immunohistochemical staining, respectively. Western blotting was employed to detect the expression of Snail 1 protein in the renal cortex. RESULTS: The levels of blood glucose, Scr, kidney weight index were increased remarkably in diabetic rats as compared with those in control groups (P<0.05, P<0.01), and decreased remarkably in the insulin-treated rats as compared with those in the diabetic rats (P<0.05, P<0.01). The Snail 1 protein was not detected by immunohistochemical staining in normal renal tissues. However, strongly positive staining was observed in renal tubules of diabetic rats. A time-dependent loss of Snail 1 expression was detected in the kidney in insulin-treated rats. The Snail 1 protein and mRNA of Snail 1 and FN were significantly up-regulated in the diabetic rats as compared with those in controls (P<0.01), while down-regulated in the insulin-treated diabetic rats (P<0.01). A close positive relationship existed between the mRNA expression of Snail 1 and FN (r=0.800, P<0.01). The level of Snail 1 protein expression was positively correlated with blood glucose, urine protein, Scr, kidney index (r=0.877, 0.694, 0.522, 0.875, P<0.01). CONCLUSION: These findings suggest that Snail 1 gene and protein expression are up-regulated in the kidney of rats with diabetes and may be involved in the pathogenesis of diabetic nephropathy.