Effect of losartan on the glomerular protein expression profile of type 2 diabetic KKAy mice / 中华肾脏病杂志

ABSTRACT

Objective To investigate the effects of angiotensin receptor blocker (ARB)losartan on the glomerular protein expression profile of spontaneous type 2 diabetic KKAy mice by two-dimensional differential gel eleetrophoresis and MALDI-TOF mass spectrometry.Methods 8-week-old spontaneous type 2 diabetic KKAy mice were randomly divided into losartan (10 mg·kg-1·d-1 given in drinking water) treatment group and non-treatment group.Eight-week-old C57BL/6 mice were used as normal control.The glomeruli were separated by magnetic bead perfusion through thoracic aorta at age of 20 weeks,then glomerular protein was extracted.The glomerular protein expression profile was investigated by CyDyes minimal fluorescence labelling,two-dimensional differential gel electrophoresis and MALDI-TOF mass spectrometry.Results KKAy mice developed higher body weight and blood glucose,higher urinary microalbumin creatinine ratio at age of 20 weeks than C57BL/6 mice at the same age (all P＜0.05).Losartan treatment markedly reduced urinary microalbumin creatinine ratio [(539.71 ±100.23)mg/g vs (728±177.19) mg/g],attenuated mesangial expansion and the thickening of glomerular basement membrane,but had no effect on the blood glucose.By DeCyder 2-D differential analysis software,62 protein spots of differential expression were found in glomeruli between losartan treatment and non-treatment KKAy mice at age of 20 weeks.Among them,41 proteins were identified by peptide mass fingerprinting.The expressions of 28 proteins were up-regulated by losartan treatment,including glycerokinase,sulfite oxidase,glycine amidinotransferase,adenosylhomocysteinase,etc.The expressions of 13proteins were down-regulaled by losartan treatment,including 3-mercaptopyruvate sulfurtransferase,ATP synthase subunit d,60 000 heat shock protein,stress-70 protein (alternative name 75 000glucose-regulated protein,GRP75),etc.Six differcntially expressed proteins were found in glomeruli between non-treatment KKAy mice and C57BL/6 mice,and the differential expressions were suppressed by losartan treatment,including dihydrolipoyllysine-residue acetyltransferase component of pyruvate dehydrogenase complex,succinyl-CoA ligase (GDP-forming) subunit beta,mitochondrial,ATP synthase subunit d,GRP75,nucleoside diphosphate-linked moiety X motif 19 and seleniumbinding protein 1.Conclusions Losartan significantly reduces the urinary protein excretion rate and renal pathological lesion of spontaneous type 2 diabetic KKAy mice,and suppresses the differential expression of mitochondrial ATP synthase subunit d,GRP75,selenium-binding protein 1,etc in glomeruli.Losartan may play a renoproteetive role by reducing glomerular mitochondrial reactive oxygen species genesis and inhibiting oxidative stress.