ABSTRACT
Objective To observe the change of expression of WNT4/β-catenin signaling pathway and its inhibitory factor secreted frizzled-related protein 1 (SFRP1) in renal tissue in diabetic nephropathy(DN) rats, and to explore its possible role in the development of renal fibrosis. Methods Rats were randomly divided into normal control(NC) group and DN group, and equipped with 8 in each group. The IDDM model was prepared by tail vein injection of STZ 55 mg/kg. Hemotoxyin and eosin、Periodic Acid-Schiff and Masson stain were used to observe the morphological structure and fibrotic lesions in renal tissue;Immunohistochemical analysis was used to observe the protein expression of WNT4 and β-catenin in renal tissue;Western blot was used to detect the protein expression changes of WNT4, SFRP1, β-catenin, p-GSK-3β, GSK-3β, Collagenl, a-SMA, E-cadherin in renal tissue in each group;The mRNA expression of WNT4 and SFRPl in renal tissues of rat was detected by realtime PCR. Results Compared with NC group, renal tissue fibrosis was obvious in DN group. Compared with NC group, the protein and mRNA expressions of WNT4 significantly increased (P＜0.05), the protein expressions of β-catenin, p-GSK-3β, α-SMA and collagen I significantly increased (P < 0.05), the protein expressions of Ecadherin significantly decreased (P＜0. 05), the protein and mRNA expression of SFRPl significantly decreased (P＜0.05). Conclusions In the case of DN, the signal pathway of WNT4/β-catenin is abnormal activation. The expression of SFRPl is decreased, and that may inhibit this pathway and promote the development of renal fibrosis in DN.
ABSTRACT
AIM:To observe the effects of suberoylanilide hydroxamic acid(SAHA )on the expression of Twist,histone deacetylase 1(HDAC1),and the factors associated with epithelial-mesenchymal transition and extracellular matrix in diabetic rat renal tissues and its possible mechanism.METHODS:The rat model of diabetes mellitus(DM)was established by injection of streptozotocin.The rats were randomly divided into normal control(NC)group,DM group and SAHA group.When the model was successfully established for 8 weeks ,the rats in SAHA group were intragastrically trea-ted with SAHA at dose of 25 mg· kg-1 · d-1.After 8 weeks of treatment ,the rats were sacrificed.The biochemical pa-rameters and renal index were measured ,and the pathomorphological changes of the renal tissues were observed by HE and Masson staining.In addition ,the expression of Twist in renal tubular epithelial cells was evaluated by immunohistochemis -try.The protein levels of Twist,HDAC1,E-cadherin,α-SMA and collagen type Ⅳ(Col-Ⅳ)were determined by Western blot.The mRNA expression of Twist was detected by real-time PCR.RESULTS:The blood glucose ,24 h urine protein and kidney index in DM group were all obviously higher than those in NC group ,while kidney index was reduced in SAHA group as compared with DM group(P<0.05),but the blood glucose and 24 h urine protein markedly wasn't influenced by SAHA treatment.Compared with NC group,the mRNA and protein levels of Twist and protein levels of HDAC 1,α-SMA and Col-Ⅳwere increased in DM group(P<0.05),while they decreased in SAHA group as compared with DM group(P<0.05).The protein level of E-cadherin in NC group was higher than that in DM group ,and that was increased in SAHA group as compared with DM group(P<0.05).The correlation analysis showed that the Twist protein level was positively correlated with the HDAC1 protein level(P<0.05).CONCLUSION:SAHA decreases the expression of Twist and attenuates renal tubule fibrosis in DM rats by inhibiting the expression of HDAC 1 and Twist,thus promoting the tran-scription of E-cadherin.
ABSTRACT
Transforming growth factor-β1 (TGF-β1)-activated phosphoinositide-3-kinase (PI3K)-protein kinase B (PKB/Akt) pathway is intimately related to the development of diabetic nephropathy (DN), which is negatively regulated by phosphatase and tensin homolog deleted on chromosome ten (PTEN). The present study was to investigate the expression of PTEN in the renal tissue of diabetic mellitus (DM) rats and explore its possible effect on development of DN. Sixteen Sprague-Dawley rats were divided into normal control group (n = 8) and diabetic group (n = 8) at random. Streptozotocin injection was used to establish diabetic model. After 12 weeks, the rats were sacrificed to detect relative biochemical parameters and renal index, and to observe the changes of pathomorphology by HE staining as well. In addition, immunohistochemistry staining and Western blotting were employed to detect the protein expression of PTEN, TGF-β1, PI3Kp110α, Akt1, p-Akt1 (Ser(473)), fibronectin (FN) and Collagen IV, respectively. Furthermore, the expression of PTEN mRNA was also examined by RT-PCR. The results indicated that the levels of blood glucose, serum creatinine and urine protein (24 h) were increased remarkably in the diabetic group (P < 0.05) compared with those in the control group. Compared with those in the control group, the protein expressions of TGF-β1, PI3Kp110α, Akt1 in renal tubular epithelium and the expressions of FN and CollagenIV in renal interstitium were increased in the diabetic group (P < 0.05). The expression of PTEN in the diabetic group was significantly reduced than that in the control group (P < 0.05), and the expression of p-Akt1 (Ser(473)) increased remarkably in the diabetic group which had the similar trend to Akt1 (P < 0.05). PTEN mainly located in renal tubular epithelial cells. The expression of PTEN had negative correlation to that of p-Akt1 (Ser(473)). Compared with that in the control group, the expression of PTEN mRNA was decreased remarkably in the diabetic group (P < 0.05). The data suggest that the down-regulation of PTEN in renal tissue of DM rats may promote the PI3K-PKB/Akt pathway over-activated by TGF-β1, which facilitates the initiation and development of DN.