PC21 EFFECT OF OBESITY ON ADIPOSE TISSUE PEPTIDE SECRETION: A PROTEOMICS APPROACH TO DIABETES TYPE II

Abstract

Introduction: The world wide prevalence of type II diabetes mellitus is increasing rapidly. Dietary fats and rapid digestible carbohydrates are believed to play an important role in the development of this type of diabetes. In patients with type II diabetes, insulin is less able to promote the uptake of glucose into muscle and liver and to inhibit the production of glucose by the liver. The underlying mechanisms by which diet components induce a state of insulin resistance are largely unclear. Adipose tissue is thought to play a central role in the development of the insulin resistant phenotype. During obesity adipocytes maturate (enlarge) by storing triglycerides. Besides its role in energy storage, these differentiated adipocytes function as an endocrine organ that secretes numerous peptide hormones such as leptin, resistin. adiponectin and TNFá. These proteins have been shown to play a role in the regulation of food intake (leptin) and the development of insulin resistance (TNFá, resistin, adiponectin). It is anticipated that differentiated adipocytes produce yet unknown peptide hormones that may play regulatory roles in glucose and fatty acid metabolism. The aim of the study is to determine the effects of obesity and insulin resistance on the adipose tissue secretome using proteomics technology. Methods: Adipose tissue, isolated from control (+/−) and obese, leptin deficient and insulin resistant ob/ob −/− mice, was cultured for 3 days in M199 media supplemented with insulin (50 nM) and gentamycin (50 μg/ml). Subsequently protein profiles of the conditioned media were generated using SELDI proteinchip technology (Ciphergen biosystems). The media, diluted 2-fold in binding buffer (NH4Ac pH 4.0/0.05% triton x-100) were applied to weak cation exchange (WCX) proteinchips and, after washing, they were analyzed by time of flight mass spectrometry. Results: Data from the 2–50 kDa range show 41 peptides that are clearly increased and 10 peptides were found decreased in the ob/ob −/− media compared to control media. Conclusion: Results show that in total 51 peptides in the range of 2 to 100 kDa have altered secretion patterns when comparing adipose tissue from obese and lean mice indicating that major changes take place in the adipose tissue secretome during insulin resistance. The discovered proteins have to be further identified to determine their exact function and role in the development of diabetes type II.