Protective Effect Of Cardiac High Expression Of Metallothionein On Diabetic Cardiomyopathy And Diabetic Nephropathy Caused By Akt2 Deficiency

Background:Diabetes mellitus is a chronic disease that seriously affects people's quality of life,and the heart and kidney have the highest mortality rate among the organs involved in diabetes mellitus complications.Two important mechanisms of damage caused by diabetes are oxidative stress damage and inflammatory damage,and metallothionein(MT)is one of the main anti-oxidative stress moleculars of the body.Metallothionein has been shown to reduce the damage in diabetic cardiomyopathy and is Akt2 dependent.However,it is unclear whether metallothionein in the absence of Akt2 has a protective effect on the diabetes caused by Akt2 deficiency,and there is no studies on whether highly expressed metallothionein in the heart can protect the distal organs from damage caused by Akt2 deficiency.Object:To investigate the protective effect of cardiac-specific high expression of metallothionein on diabetic cardiomyopathy and diabetic nephropathy caused by Akt2 deficiency.Methods:Age-matched male and female mice were selected according to genotype with at least six mice in each group,and each genotype was wild type(WT),heart-specific high expression of metallothionein(MT-TG),systemic Akt2 knockout(Akt2-KO)and MT-TG and Akt2-KO mice cross-breeding(MT-TG/Akt2-KO).Mice were uniformly sacrificed at 24 weeks,and cardiac echocardiography and glucose blood tolerance texts were finished before sacrificed.Mice's hearts and kidneys were taken for histological staining and Western blotting,including measurement of mouse weight,organ weight to tibia length ratio,WGA staining,Sirius red staining,PAS staining,and Western blotting for fibrosis proteins(FN,COL1A1,TGF-?),inflammatory proteins(ICAM-1,VCAM-1,IL-1?),oxidative stress proteins(3-NT,4-HNE,CAT,SOD2),glucose metabolism-related proteins(Takt and its phosphorylation,Akt2 and its phosphorylation,Akt1 and its phosphorylation,GSK-3? and its phosphorylation,GS and its phosphorylation,AS160 and its phosphorylation,HK,PFKFB2 and its phosphorylation),other pathway proteins(ERK and its phosphorylation),some kits(blood insulin,24-hour urine protein,serum MT measurement).Results:Both male and female Akt2 knockout mice showed increased blood insulin and decreased blood glucose tolerance at 24 weeks.Akt2 deletion resulted in cardiac remodeling(wall thickening and ventricle enlargement)and damaged cardiac function,and WGA staining showed cardiac cells hypertrophy,all of which suggest that Akt2 deletion leads to hypertrophy at the organ and cellular levels of the heart,and Sirius red staining showed collagen accumulation in the myocardium of Akt2 mice,suggesting increased fibrosis at the cardiac tissue level.In contrast,high cardiac expression of MT reduces the damage caused by Akt2 deficiency.Fibrotic proteins(FN,COL1A1,TGF-?)were increased at the protein level in Akt2-KO mice,and inflammatory proteins(ICAM-1,VCAM-1,IL-1?)and oxidative stress proteins(3-NT,4-HNE)were also increased in Akt2-KO mice,and MT-TG decreased the expression of these proteins,and anti-oxidative stress proteins(CAT and SOD2)were decreased in mouse hearts due to Akt2 deletion,whereas antioxidant protein expression was increased in MT-TG/Akt2-KO mice hearts.Among the glycogen synthesis and phosphorylation-related proteins(GSK-3?,GS,GP)resulted in reduced glycogen synthesis after Akt2 deletion,glucose transport-related protein(AS160)showed weaker glucose transport activity after Akt2 deletion,and glycolysis(HK,PFKFB2)suggested impaired glycolysis after Akt2 deletion,while the above changes were The above changes were alleviated after MT-TG.This protective mechanism does not originate from the activation of other isoforms of Akt2(Akt1),but is probably activated by activation of the ERK pathway.The same situations are in the kidney.renal function is reduced after Akt2 deletion(24 h urine protein)mice with increased renal fibrosis(Sirius red staining,Western blotting FN,COL1A1,TGF-?),increased inflammatory damage(protein ICAM-1,VCAM-1,IL-1?)oxidative stress damage(3-NT,4-HNE),increased glycogen synthesis(GSK-3?,GS)was reduced,glucose transport(AS160)was reduced,and glycolysis(HK)was reduced,and these alterations were significantly ameliorated after cardiac-specific high expression of MT.This distal ameliorative effect was not improved by direct secretion of cardiac MT into the blood.Conclusion:By examining the function of heart and kidney of transgenic mice with high MT expression in the heart and systemic Akt2 knockout cross-breeding,staining of pathological tissue sections,and western blotting of tissue proteins,this study revealed for the first time the protective effect of MT on diabetic cardiomyopathy caused by Akt2 deficiency,including cardiac remodeling and cardiac function,degree of fibrosis,degree of inflammation and oxidative stress damage and glucose metabolism-related pathways,and This protective effect was not dependent on Akt2,probably due to activation of ERK pathway.High cardiac MT expression also has a protective effect on diabetic nephropathy caused by Akt2 deficiency,but this protective effect does not result from the secretion of MT into the blood through the heart.The exact cause needs to be further investigated.