Effect Of Glutathione S-Transferase Mu And Down-Regulation Its Expression In The Progression Of Diabetic Nephropathy

Background and Objective The incidence of diabetes mellitus(DM) and diabetic complications has increased in developed countries.Chronic hyperglycemia participates in the development of diabetic complications such as atherosclerosis, cardiac dysfunction,and nephropathy.Diabetes now accounts for 40%of patients with kidney disease,and the number of renal failure patients with diabetes is expected to increase in the coming years.Diabetic nephropathy is a serious microvascular complication of DM and one of the main causes of end-stage renal disease,which is a major cause of morbidity and mortality in diabetic patients.Despite decades of intensive research into its pathogenesis,the triggering factors and underlying mechanism behind the development of DN remain largely unknown.2-D difference gel electrophoresis(2-D DIGE) was applied to investigate the potential mechanisms of diabetic nephropathy(DN).We expected to figure out which proteins participated in the DN onset.PartⅠThe Expression of Glutathione S-transferase Mu on the Renal Tissue of STZ-induced Diabetic RatsObjective 2-D difference gel electrophoresis(2-D DIGE) was applied to investigate the potential mechanisms of diabetic nephropathy(DN).We expected to figure out which proteins participated in the DN onset.Material and Methods Male Wistar rats randomly divided into two groups:diabetic group(DM group) and control group(C group).The DM group were injected 1%streptozotocin(STZ) through the tail vein to induce diabetic rats.After 24 weeks,the fasting plasma glucose(FPG),urea nitrogen (BUN),serum creatinine(SCr),glycosylated hemoglobin(HbAlc) and advanced glycation end products(AGEs) were determined.The pathologic changes of renal tissue were observed.2-D difference gel electrophoresis and mass spectrometry were applied to identify differential expression renal proteins among the control and DM groups,the expression of GSTM in the kidney of control and diabetic rats was carried out by Western blot analysis.Results The levels of FBG,HbAlc,AGEs,BUN and SCr of DM group were higher than that of DM group(P＜0.05).The pathologic changes were deteriorated in DM group.Twenty-five differential expression proteins were found in the renal tissue of DM group.The protein with SSP No.1252 was identified as Glutathione S-transferase mu(GSTM) which was found up-regulated in the kidneys of diabetic rats.The expression of GSTM mRNA of diabetic rats were significantly higher than that of control rats(P＜0.01),which was accordance with the result of 2-D DIGE.Condusions 1.Twenty-five differential expression proteins were found in the renal tissue of DM group.These proteins are most likely to participate in the deterioration and restoration as important functional proteins,and to provide with target candidate for treatment in DN.2.The expression of GSTM mRNA of diabetic rats were significantly higher than that of control rats(P＜0.01).We will evaluate the effect of up-regulated expression of GSTM.PartⅡEffects of high-glucose induced the expression of GSTM in rat mesangial cells and effects of resveratrol on rat mesangial cellsObjective The present study was aimed to evaluate the expressin of GSTM in the mesangial cells and research the protective effects of resveratrol(Res) on glucose-induced proliferation of mesangial cells.Methods The cultured mesangial cells were divided into five groups:control group(C group),high glucose group(HG group,25mM glucose),T1 group(2.5microM Res+25mM glucose),T2 group(5microM Res+25mM glucose) and T3 group(10microM Res+25mM glucose). The effect of Res on mesangial cell proliferation was assessed by MTT and CCK8. The percent of apoptosis and cell cycle were examined by flow-cytometry.The expression of GSTM and Nrf2 were detected by Western blot analysis.Results 1.The viability in HG group was higher compared to C group(P＜0.01).After treatment with Res,the viability was lower compared to HG group(P＜0.05).2.The percent of G1 in HG group increased relative to C group(P＜0.05).After treatment with Res,the percent of G1 in T3 group dereased compared to HG group(P＜0.05).The percent of S in HG group reduced compared to C group(P＜0.01).After treatment with Res,the percent of S in T2 and T3 groups increased compared to HG group(P＜0.01).3.The percent of apoptosis in T2 and T3 groups were higher compared to HG group (P＜0.01).4.The expressions of GSTM and Nrf2 in HG group were increased relative to C group(P＜0.001).Res treatment reduced the expressions of GSTM and Nrf2 in T3 and T2 groups compared to HG group(P＜0.01).Conclusions 1.The up-regulated expression of GSTM was found in high-glucose cultured mesangial cells.It may be one of the causes resulting in the up-regulated expression of GSTM in kidney.2.The expression of GSTM decreased after treatment with resveratrol.The expression of Nrf2 was reduced due to resveratrol therapy,which leaded to the down-regulated expression of GSTM.3.The high glucose induced proliferation of mesangial cells was inhibited by resveratrol therapy.The mechanisms of the inhibition include mesangial cell S phase arrest and inducing cell apotopsis.