Lipolytic Protein Expression in Lean, Obese, and Exercise Trained Men

Abstract

Perilipins are proteins covering the surface of triglycerides that play an integral role in lipolysis within adipocytes. Perilipins prevent the hydrolysis of triacylglycerol (TAG) by blocking hormone sensitive lipase (HSL) access to the lipid surface, promoting lipid storage. Adipose triglyceride lipase (ATGL) activates TAG hydrolysis. HSL is the rate limiting step for hydrolysis of diacylglycerol. PURPOSE: It was the purpose of this study to determine perilipin, ATGL, and HSL protein content in lean (LN) and obese (OB) sedentary and lean exercise trained (ET) men. METHODS: Abdominal subcutaneous adipose tissue biopsies were taken from 9 OB (BMI>30 kg/m2), 7 LN (BMI≤25 kg/m2), and 4 ET men. Protein content was measured using Western Blots. RESULTS: Perilipin protein content was lower in OB and ET than LN (OB: 4,426.2±681.8, ET: 3,374.4±241.0, LN: 19,011.3±3449.5 a.u., p<0.01). OB ATGL protein content was approximately 60% that of LN and ET, but was not significantly different (OB: 2,324.9±556.3, LN: 3,774.3±909.9, ET: 3,673.5±737.1, P=0.20). HSL protein content was lower in OB than LN and ET (OB: 5,893.0±1213.8, LN: 11,413.5±1835.6, ET: 11,701.55±1419.7, p<0.05). CONCLUSION: We found that perilipin protein content is lower in OB and ET participants than LN. ATGL protein content tended to be lowest and HSL protein content was lowest in OB participants as compared to their lean counterparts. Supported by NIH Grant 1R15DK074401-01.