Mitochondrial Damage and Protein Modification in the Diabetic Kidney Mouse Model

Abstract

A hallmark of diabetes is increased levels of oxidative stress, such as superoxide formation. Superoxide can have detrimental effects on the mitochondria by increasing reactive nitrogen species (RNS) and generating other reactive oxygen species (ROS). We hypothesize that diabetes induced oxidative stress leads to mitochondrial membrane permeability and protein modification in the diabetic mouse model. In this study, diabetes was induced in the mouse though a 6-week regiment of a high calorie, high fat diet. Kidney tissue samples from wild type control and diabetic groups were harvested and extracellular, cytosolic and mitochondrial protein fractions were isolated. Western blot proteomics reveal increased NADPH oxidase and decreased thioredoxin levels, indicating a condition of oxidative stress in the diabetic model. Additional Western blots show mitochondrial damage through membrane leakage through increased levels of the mitochondrial proteins cytochrome-c and prohibitin in the cytosolic diabetic fraction. Two-dimensional Western blots of the mitochondrial fractions show increased protein modification through tyrosine nitration. It is concluded from this experiment that diabetes increases oxidative stress, resulting in increased mitochondrial membrane permeability and increased protein modification through tyrosine nitration.