Endothelial lipase mediates efficient lipolysis of triglyceride-rich lipoproteins

by Sumeet A. Khetarpal, Cecilia Vitali, Michael G. Levin, Derek Klarin, Joseph Park, Akhil Pampana, John S. Millar, Takashi Kuwano, Dhavamani Sugasini, Papasani V. Subbaiah, Jeffrey T. Billheimer, Pradeep Natarajan, Daniel J. Rader Triglyceride-rich lipoproteins (TRLs) are circulating reservoirs of fatty acids used as vital energy sources for peripheral tissues. Lipoprotein lipase (LPL) is a predominant enzyme mediating triglyceride (TG) lipolysis and TRL clearance to provide fatty acids to tissues in animals. Physiological and human genetic evidence support a primary role for LPL in hydrolyzing TRL TGs. We hypothesized that endothelial lipase (EL), another extracellular lipase that primarily hydrolyzes lipoprotein phospholipids may also contribute to TRL metabolism. To explore this, we studied the impact of genetic EL loss-of-function on TRL metabolism in humans and mice. Humans carrying a loss-of-function missense variant inLIPG, p.Asn396Ser (rs77960347), demonstrated elevated plasma TGs and elevated phospholipids in TRLs, among other lipoprotein classes. Mice with germline EL deficiency challenged with excess dietary TG through refeeding or a high-fat diet exhibited elevated TGs, delayed dietary TRL clearance, and impaired TRL TG lipolysisin vivo that was rescued by EL reconstitution in the liver. Lipidomic analyses of postprandial plasma from high-fat fedLipg-/- mice demonstrated accumulation of phospholipids and TGs harboring long-chain polyunsaturated fatty acids (PUFA...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research