Department of Physics, Chemistry and Biology Master's Thesis Oxidative Stress and Protein Acetylation in Adipocytes

Obesity is an increasing health problem which is causally associated with insulin resistance and type 2 diabetes. Oxidative stress, i.e. overproduction of reactive oxygen species, is associated with insulin resistance and obesity and may be a major risk factor in the onset and progression of diabetes. Bernlohr Lab at University of Minnesota has studied oxidative stress in adipocytes by silencing the enzyme glutathione S-transferase A-4 (GSTA4), an enzyme detoxifying 4-hydroxynonenal formed during oxidative stress. Their results indicate that lysine acetylation, an important post-translational modification, may be involved during oxidative stress. In this study lysine acetylation has been investigated in condition of oxidative stress in 3T3L1 adipocytes and subcutaneous adipose tissue from mice using SDS-PAGE gel electrophoresis and western blot. Lysine acetylation was analyzed in different compartments of the cell such as in cytoplasm, mitochondria as well as in whole cell extracts. Silencing of GSTA4 and stimulation by TNF-α in 3T3-L1 adipocytes resulted in an increase of lysine acetylation in cytoplasm. Furthermore, stimulation by IL-6 did not have any effect on lysine acetylation. Surprisingly, subcutaneous adipose tissue from mice fed on a high-fat diet showed a decrease of lysine acetylation in cytoplasm compared to mice fed on a chow diet. In conclusion, lysine acetylation seems to change during oxidative stress and may be an important factor during insulin resistance, type 2 diabetes and obesity. Therefore, studying lysine acetylation and enzymes modulating acetylation may potentially increase our understanding of insulin resistance, type 2 diabetes and obesity and could lead to new therapies. Table of contents Abbreviations .......................................................................................................................................... 7