Lipin-1γ isoform is a novel lipid droplet-associated protein highly expressed in the brain

Lipin-1 proteins are phosphatidic acid phosphatases (PAPs) catalyzing the conversion from phosphatidic acid (PA) to diacylglycerol (DG). Two alternative splicing isoforms, lipin-1 alpha and -1 beta, are localized at different subcellular compartments. A third splicing isoform, lipin-1 gamma was recently cloned and its subcellular localization is unknown. Here, we demonstrate that lipin-1 gamma is localized to lipid droplets (LDs), an association mediated by a hydrophobic, lipin-1 gamma-specific domain. Additional expression of lipin-1 gamma altered LD morphology without affecting the triacylglycerol (TG) level. In human tissues, lipin-1 gamma is the main lipin-1 isoform expressed in normal human brain, suggesting a specialized role in regulating brain lipid metabolism. (C) 2011 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.