The role of TGF-β1/SGK1 signaling pathway in diabetic nephropathy

Abstract

Objective To explore the role of transforming growth factor-β1/serum and glucocorticoid induced kinase 1 (TGF-β1/SGK1) signaling pathway in diabetic nephropathy (DN). Methods Totally 60 clean grade healthy male Sprague-Dawley (SD) rats were divided into normal control (Con group, n=20) and diabetic model group (diabetic group, n=40). Type 2 diabetic animal model was induced by intraperitoneal injection of streptozotocin (STZ, 45 mg/kg) to SD rats. Half of rats in each group were sacrificed after implemented for 4 weeks and 8 weeks, respectively. Fasting glucose, serum urea and creatinine, as well as urine protein in 24 h were detected. Pathological changes of rats' kidney cortex tissue were examined by hematoxylin-eosin staining. The expression of SGK1 was detected by immunohistochemistry in renal tissue. The mRNA level of SGK1 was analyzed by real-time polymerase chain reaction (PCR). The protein expression of TGF-β1 and SGK1 were determined by Western blotting. Results Compared to the control group, the blood glucose of the diabetic group rats was significantly increased, kidney hypertrophy index, serum urea and creatinine, 24 h urine volume and urinary microalbumin as well as kidney index were significantly higher (P<0.05). The mRNA expressed of SGK1, protein expression of TGF-β1 and SGK1 were also increased obviously in the renal cortex of diabetic rats (all P<0.05 vs Control). Conclusions TGF-β1/SGK1 signaling pathway is closely related to the TIF damage of kidney cortex in diabetic rats. Key words: Transforming growth factor beta/ME; Protein kinases/ME; Diabetic nephropathies/ME