| Objective:Diabetic nephropathy(DN) is one of the most common microvascular complications of diabetes mellitus(DM). In the early stage, its pathological features are the glomerular hypertrophy and mesangial hyperplasia, but it was characterized by glomerular and interstitial fibrosis in the later stage. In recent research, transforming growth factor-β(TGF-β) is closely related to renal fibrosis,which is the one of the key cytokines to cause DN.Activated TGF-β/Smad signal pathway can induce epithelia-mesenchymal transition(EMT), increase synthesis and decrease degradation of extracellular matrix. That results in accumulation of extracellular matrix which can finally cause extensive renal tissue fibrosis. SnoN protein is the important endonuclear transcription co-repressor. It has been discovered that SnoN can regulate TGF-βsignal to emerge cytological effect through interaction with Smad protein at downstream of TGF-β. SnoN which mediated the endonuclear inhibition of transcription activity before the transcription of TGF-βtarget gene, acts an important role in regulating TGF-β/smad signal path. To evaluate whether transcription co-repressor SnoN protein is degraded and the mechanism of it in the early DN of diabetic rats, we injected streptozotocin(STZ) to rats at one-time to induce early type 1 DN rats and then used MG132,a inhibitor of proteasome, with intraperitoneal injection to reveal the possibility of proteasome inhibito, r's treatment to cure diabetic nephropathy. Method:1,Establishing and grouping of DM model: 30 healthy male Wistar rats randomly divided to two groups:22 DM model and 8 NC. Model group rats are once peritoneal injected STZ (60 mg/kg) while normal control group rats are injected isovolumetric citral damping fluid.22 model group rats are brought to experiment and randomly divided to 2 groups:Diabetes control (DC group) and diabetes therapy(DT group):0.1mg/kg.d MG132 peritoneal injection. Every day DC group and NC group rats are peritoneal injected isovolumetric 0.9% physiological saline. 2,In 6 weeks and 8 weeks'check, collecting rats' urine and detecting 24 hour urine protein ration, blood-fasting sugar and CysC. 3,renal tissue pathology detecting:cleaning and taking kidney, Paraffin Embedding, dying with HE and Massion, observing interstitial basic pathology and fibrosis change of glomerulus and tubules. 4,Immunohistochemisty and Western-blot detecting Nephridial tissue SnoN protein expression. 5,Fluorescent quantitation RT-PCR detecting Nephridial tissue SnoN's mRNA expression. 6,Statistical treatment: SPSS13.0 is used to analyzing data which is expressed by x-±s, one-factor analysis of variance is used to comparing between groups, q-detecting is used to compare two monomers, t-detecting is used to compare monomers in group,α=0.05, P<0.05. Results:1,general index: weight:compared with NC group, Model group decreases obviously(P<0.05); compared with DC group, the DT group increases; the differences in 8 weeks is more obvious(P<0.05).②blood sugar:NC group is at normal level fluctuation, Model group is higher than NC group(P<0.05); there is no obvious difference between DT group and DC group (P>0.05); the change tendency in 8 weeks and 6 weeks is the same, there is no obvious difference between 8 weeks and 6 weeks(P>0.05).③CysC:there is no obvious difference between groups, as well as in 8 weeks and 6 weeks (P<0.05).④24-hour urine protein ration:compared with NC group, there is microalbuminuria in model group, especially in DC group, the difference is of statistical significance(P<0.05); the change tendency in 8 weeks and 6 weeks is the same, there is no obvious difference between 8 weeks and 6 weeks.2.HE and Masson dyeing:①HE dyeing:compared with NC group,. Compared with DC group, DT group kidney glomerulus grows down; in 8 weeks DC group kidney glomerulus accretes, kidney tubules swells as well as in 6 weeks, the tendency is the same.②Masson dyeing:compared with NC group, DC group visible renal interstitium blue masccline deposition increases while DT group decreases, in 8 weeks is lighter than in 6 weeks, the increasing tendency is the same.3.Nephridial tissue SnoN albumen immunohisto- chemisty expression:SnoN albumen expression can be seen in NC group, compared with NC group, expression amount decreases in DC group, there is more in DT group than in DC group. The expression amount in 8 weeks is less than in 6 weeks, the tendency is the same as in 6 weeks.4,Nephridial tissue SnoN wester-blot detectation: SnoN protein electrophoresis strip gradation analysis results that there is high level SnoN protein expression in NC group, there is less in NC group than in DC group, SnoN protein expression increases in MG132 treated DT group than in DC group (P<0.05). SnoN protein expression is less in 8 weeks than 6 weeks, the tendency is the same as in 6 weeks (P<0.05).5,Nephridial tissue SnoN mRNA expression:there is no obvious difference between groups. There is no obvious difference between in 6 weeks and in 8 weeks (P<0.05). Conclusion:1,SnoN protein in early DN rats is at low expression because of polyubiquitinated degradation.2,Prosome inhibitor can restrain DN SnoN protain's polyubiquitinated degradation, thus inhibit the activition of TGF-β/Smad pathway in DN, can act therapeutical effect to DN. |
