The Mitophagy And Mitophagy-related Protein Expression In Renal Tubular Epithelial Cells Of STZ Induced Mice With Diabetic Nephropathy

Objective:To establish a mouse model of type1diabetic nephropathy to:1. observe the condition of mitophagy of renal tubular epithelial cells in the mouse models with type1diabetic nephropathy and2. investigate the expression of NIX-a mitophagy related regulatory protein in renal tubular epithelial cells in mouse mlodels with type1diabetic nephropathy.Methods:(1)17ICR mice were randomly divided into control (n=5), diabetic nephropathy (DN)(n=6) and3-MA groups (n=6). At the end of the8th week, all mice were sacrificed, and their kidneys were harvested.(2)The mRNA expression of NIX were tested by RT-PCR.(3)The protein expression of LC3,P62,and NIX were tested by western blot test and immunohistochemistry.(4)The co-stainings of LC3and VDAC were tested by confocal laser scanning microscope.(5)The mitophagy in renal tubular epithelial cells was observed by electron microscopyResults:(1) Mouse model of type1diabetic nephropathy was successfully constructed. After72hours, blood from tail vein was sampled and blood glucose was measured. When the fasting blood glucose was maintained at13.9mmol/L glucose, remained at or randomly detected to be16.7mmol/L or more, the mouse is considered a diabetic model. At the end of the8th week, the blood glucose of diabetic nephropathy and3-MA groups were significantly higher than the control group. Glomerular basement membrane (GBM) thickening, glomerualr mesangial cell proliferation and compensatory expansion of renal tubular cells were observed in diabetic nephropathy and3-MA groups.(2) The protein and mRNA expression of Nix were increased in diabetic nephropathy compared to mice in control groups.3-MA mice’s protein and mRNA expression of Nix were decreased compared with those of STZ mice. Compared to the mice in control group, the protein levels of LC3and P62of STZ mice were increased.3-MA mice’s protein level of LC3and P62was decreased compared with that of STZ mice.(3) VDAC co-localization with LC3was increased in diabetic nephropathy compared to mice in control groups. VDAC co-localization with LC3was decreased in3-MA mice.(4) Electron microscopy revealed that mitophagy in renal tubular epithelial cells was observed in STZ mice and was not observed in mice in control groups and3-MA groups.Conclusions:(1) Abnormal expression of mitophagy related proteins was observed in renal tubular epithelium of mice with diabetic nephropathy.(2) Mitophagy was observed in STZ mice.(3) Abnormal expression of Nix exists in STZ mice.In summary, mitophagy may be involved in the pathogenesis of diabetic nephropathy, and Nix may be involved in the mitophagy of diabetic nephropathy.