Submitted to: Journal of Lipid Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2009
Publication Date: 11/10/2009
Citation: Shen, W., Patel, S., Miyoshi, H., Greenberg, A.S., Kraemer, F.B. 2009. Functional interaction of hormone-sensitive lipase and perilipin in lipolysis. Journal of Lipid Research. 50(11):2306-2313. Interpretive Summary: Obesity is occurring at epidemic levels in humans and increasing the risk of developing diabetes, heart disease, and cancer. Understanding the factors in our bodies that regulate body weight and body fat accumulation will allow us to develop nutritional approaches that will help prevent obesity and the associated medical complications. We discovered that within fat cells, fat is actually stored within a specific compartment of the cell which we have termed fat droplets. We have also discovered a protein, which specifically coats the fat droplets in fat cells, which we have named perilipin. We found that perilipin can regulate the breakdown of stored fat within fat droplets. Our prior research studies suggest that perilipin acts to bind and bring other proteins, whose function is to breakdown fat to the surface of fat droplets and facilitate fat breakdown. In this paper, we identified which specific parts of the perilipin protein can directly bind proteins which breakdown fat. These studies increase understanding of how fat can be broken down in cells and thus assist us in our goal of developing nutritional approaches to ameliorate obesity.
Technical Abstract: Adipocyte lipolysis is controlled by complex interactions of lipases, cofactors, and structural proteins associated with lipid droplets. Perilipin (Plin) A is a major droplet-associated protein that functions as a scaffold, both suppressing basal and facilitating cAMP-dependent protein kinase (PKA)-stimulated lipolysis. Plin is required for the translocation of hormone-sensitive lipase (HSL) from the cytosol to lipid droplets upon stimulation. In these studies, we provide direct evidence for a physical interaction of HSL with Plin. By coexpressing HSL with truncation mutations of Plin, we demonstrate using co-immunoprecipitation that HSL can interact with an N-terminal region located between amino acids 141 and 200 of Plin A as well as with a C-terminal region located between amino acids 406 and 480. The N-terminal construct, Plin 1-200, which does not associate with lipid droplets but interacts with HSL, can function as a dominant negative for PKA-stimulated lipolysis. Using confocal microscopy of Plin truncations, we demonstrate that sequences between amino acids 463 and 517 may be important for or participate in lipid targeting. The results suggest the translocation of HSL to the lipid droplet occurs by virtue of Plin localization to the surface of lipid droplets and a physical interaction of HSL occurring with sequences within the N-terminal region of Plin.