The Effect On Vitamin D Receptor In Proteinuria In Diabetic Nephropathy Mice

background:Diabetic nephropathy( DN) has become a major cause of end-stage renal disease.And proteinuria is the most prominent clinical manifestation in DN patients.Its pathogenesis is complex, there is no effective treatment. Present, the main point of view: DN is a "podocyte disease." Vitamin D receptor(VDR) is widely distributed in the most body tissues and organs. including bone, kidney, skin, parathyroid, breast,etc. It has been found that vitamin D(VD)-VDR signal system has a variety of roles regulating gene expression, calcium and phosphorus metabolism, cell migration and differentiation, immune response.Currently,There are some aspects of the research on VDR in kidney disease: the expression of VDR in patients with chronic kidney disease, end-stage kidney disease and the micro-inflammatory state caused by chronic diabetes has a tendency to reduce; VDRA(vitamin D receptor agonists agents,vitamin D receptor agonist) can be partially alleviated proteinuria in DN animal models, and so on. But research on the relationship between VDR and proteinuria in diabetic nephropathy is little.Wnt/?-catenin signaling pathway involved in the body's growth, proliferation, differentiation and other physiological processes. VD-VDR signaling system has a regulatory role on the Wnt signaling pathway GSK-3?/?-catenin.But there is no reports on VDR regulating Wnt signaling pathway and its key molecule GSK-3?/?-catenin in the DN.purpose:1. Observe change of the VDR expression level in renal tissue and associated with proteinuria in diabetic nephropathy model db/db mice2. Verify that the regulation of VDR on GSK-3?/?-catenin which are the Wnt signaling pathway molecules in mouse kidney tissue;3. Use VDR agonists to observe the protective effect on VDR in podocytes and renal injury which caused by high glucose in animal models.method:5 weeks old db/db mice were randomly divided into three groups: db/db group(n=20), db/db-DMSO group(db/db-D group,n=20), db/db-paricalcitol treatment group(db/db-P group,n=20), 20 db/m mice as normal control group. From 6 weeks we collected blood, urine specimens of db/db mice to measure blood glucose, serum creatinine, urine protein compared with the corresponding data of db/m mice. For the foliowing drug intervention from 10 weeks: db/db-P group administered every other day paricalcitol 0.3?g/kg intraperitoneal injection, db/db-D group was injected with the db/db-P group, an equal volume of solvent, db/m group and db/db group was not given any treatment. Respectively, before injection, after injection of 1 month,2months,3 months(10 weeks, 14 weeks, 18 weeks, 22 weeks) were sacrificed 5 mice.We detected the expression of VDR, nephrin, podocin, GSK-3?, ?-catenin, ?-SMA and MMP9 in the renal tissue by Fluorescence quantitative real-time PCR(q RT-PCR)and Wetern blot. Preparation of pathology and electron microscopy were performed to observe changes in renal tissue structure and morphology of podocytes.The expression of nephrin, ?-catenin was detected by immunohistochemical, The expression of VDR, podocin, ?-SMA was detected by immunofluorescence.result:1. With the development of time, db/db mice body weight, blood glucose, serum creatinine and urine protein were significantly increased(P<0.05). After given paricalcitol treatment, urinary protein and serum creatinine levels decreased(P<0.05), while no significant effect on body weight, blood sugar. The expression of VDR in db/db mice renal tissue reduced while urine protein gradually increased( P<0.05).Pearson correlation analysis showed there was a certain degree of negative correlation between VDR and urine protein(r=-0.745,P<0.01).2.With the development of time, the expression of VDR in db/db mice renal tissue reduced while the expression of GSK-3?/?-catenin increased(P<0.05).After administering paricalcitol,the expression of VDR increased while the expression of GSK-3?/?-catenin decreased(P<0.05). This suggested that VDR could regulatory Wnt signaling pathway molecules.3. With the development of time, the expression of VDR,nephrin,podocin in db/db mice renal tissue decreased while the expression of ?-SMA, MMP9 increased(P<0.05).After administering paricalcitol,urinary protein decreased(P<0.05), the expression of VDR nephrin, podocin upregulated while the expression of ?-SMA,MMP9 downregulated(P<0.05), indicating that VDR can protect podocyte and kidney damage in diabetic nephropathy mice.Conclusion:VDR can protect kidney and podocyte damage caused by high glucose by regulating Wnt signaling pathway molecules, thereby reducing proteinuria.