Protective effect and mechanism of MST1 inhibition on kidney tissue in diabetic rats induced by streptozotocin / 中华肾脏病杂志

ABSTRACT

Objective To investigate the protective effect and mechanism of MST1 inhibition on kidney tissue in diabetic rats,and to find a new therapeutic target for diabetic nephropathy.Methods Total of 54 male SD rats enrolled in this study were divided into 3 groups including normal control (group A,n=18),MST1 inhibition group (Group B,n=18) and diabetes group (group C,n=18).Diabetes was induced by a single streptozotocin (STZ,50 mg/kg) injection in group B and group C.rats in group B received lentiviral vector contain Mst1 interference RNA (shRNA) and the rats in group C received empty vector.The end of 4th,8th and 12th week after modeling were considered as time points in this study.At each time point,the level of 24 hours urine protein (24-HUP),blood glucose and serum creatinine were examined.Pathological changes were observed with HE stain; Injury of podocyte and glomerular basement membrane (GBM) were examined with transmission electron microscope (TEM).The intensity and location of MST1 in kidney tissue were detected by immunohistochemistry.The level of MST1,Phosphorylated-MST1,nephrin,Caspase-3 and FasL were detected by western bloting.Results (1) At the starting point,there were no significant differences among groups in terms of weight,activity,eating and drinking.Since the end of 72nd hour after modeling,the levels of glucose in both group B and group C,compared to those in group A,significantly increased (P ＜ 0.05).There was no significant difference between group B and group C for glucose level at each time point (P ＞ 0.05); the level of 24-HUP increased significantly since the end of 4th week after modeling,and the level in group C was higher than its counterpart in group B at the same point (P ＜ 0.05); (2) There was no significant pathological lesion observed in group A.Without obvious K-W nodular changes,mesangial proliferation was observed in group B and group C.It was shown by TEM that podocyte fusion and thickening of the GBM could be found in group B and group C.The pathological change in group B was better than that in group C; (3) Compared to group A,it was shown by western blot that the levels of MST1,Phosphorylated-MST1,Caspase-3 and FasL in group B and group C were significantly higher (P ＜ 0.05),and the levels of nephrin in group B and group C were significantly lower (P ＜ 0.05) since the end of 4th week after modeling.Meanwhile,the levels of MST1,Phosphorylated-MST1,Caspase-3 and FasL in group B were significantly lower than that in group C at each time point (P ＜ 0.05),the level of nephrin in group B was significantly higher than the one in group C; (4) It was shown by immunohistochemistry that there was low MST1 expression in normal condition,especially in cytoplasm of tubular epithelial cells.The level of MST1 in group B and group C significantly increased after modeling,and the change could be the same as Western blot shown.Conclusions MST1 pathway could be involved in kidney injury induced by diabetes.MST1 inhibition could alleviate the kidney injury in STZ-induced diabetes animal model.