Expression And Regulation Of Carbohydrate Response Element-binding Protein (ChREBP) In The Kidney Of Type 1 Diabetic Mice

Carbohydrate response element binding protein is an important transcription factor in regulating glucose metabolism and lipid metabolism. It plays an important role in the regulation of mammalian glucose and lipid metabolism. Researches of liver show that glucose and insulin can regulate the expression of ChREBP. In the case of diabetes, abnormal level of glucose and insulin may result in kidney disorder of glucose and lipid metabolism by regulating the activity of ChREBP. This study was designed to detect the expression and regulation of ChREBP in diabetic kidney, and the therapeutic effects of insulin on its expression. This helps to further study the role of ChREBP in glucose and lipid metabolism of diabetic kidney.Objective:Through animal experiments and cultured primary murine proximal tubule cell experiments we investigate the distribution of ChREBP in mouse kidney and the effect of glucose and insulin to its expresion.Methods:1. Animal experiments:1) Thirty 10-week-old male C57BL/6 wild-type mice were divided into three groups randomly. Ten of it for control group. The other mice were preparated to made type 1 diabetes model by injecting streptozotocin (STZ,50mg/kg/day×5days) in intraperitoneal. the mice without treatment were diabetic group. The rest of mice were injected long-acting insulin Lantus (2-10 units/Kg×30days) in subcutaneou, which was the treatment group.2) The expression of ChREBP protein was detected with Immunostaining. Western Blot and Real-time PCR was used to detect the change of ChREBP expression of mouse kidney in the three groups.2. Cell experiment:Took insulin of 0.1u/ml concentration and glucose of different concentrations (11mmol/L,20mmol/L,25mmol/L) to stimulate the primary cultured mouse renal proximal tubule epithelial cells respectively. Western Blot was used to detect the change of ChREBP expression.Results:1. Animal experiments:1) Diabetic mice model wes created successfully. It was effective to be treated by insulin. Compared with the control group, the triglyceride and cholesterol of diabetic mice increased significantly(p<0.01), while it decreased significantly in treatment group (p<0.05).2) The results of immunohisto-chemistry showed that ChREBP mainly expresses in renal tubular, it was relatively low in glomerular. Compared with control group, the ChREBP expression of diabetic group decreased(p<0.05), while the treatment group increased(p<0.05).3). In the kidney of diabetic group mice, the total ChREBP protein level were decreased by 57% than control group mice(p<0.05), while mRNA level decreased by 39% than control group mice(P<0.01). Compared with diabetic group, the total ChREBP protein level of treatment group increased 21%(P<0.05), mRNA level increased 9%(P<0.05).2. Cell experiments:Compared with glucose of 11mmol/L, glucose of 25mmol/L could stimulate the expression of ChREBP of renal tubular epithelial cells up 28%(p<0.01). Insulin can stimulate the expression of ChREBP of cells above which was stimulated by differernt concentrations of glucose up 18%,17%(P<0.01).Conclusions:Compared with normal mice, the expression of ChREBP in renal tissue of type 1 diabetic mice decreased, while the glucose and insulin can influence the expression level of renal ChREBP. ChREBP may have something to do with the kidney glucose and lipid metabolism.