Nuclear Lipid Droplets have an active metabolism

LAGRUTTA, LUCÍA C.; LAYERENZA, JUAN P.; MOTERO VILLEGAS SANDRA; SISTI MARTÍN S.; GARCÍA DE BRAVO, MARGARITA M.; VES LOSADA, ANA

Puerto Iguazú

Congreso; 56th International Conference on the Biochemistry of lipids" (ICBL); 2015

International Conference on the Biochemistry of lipids" (ICBL)

Nuclear Lipid droplets (nLD) are nonpolar domains constituted by few small droplets, built up around a hydrophobic core of triacylglycerols (TAG) and cholesteryl esters (CE) enriched in oleic acid (OA) and surrounded by a monolayer of polar lipids, cholesterol and proteins. nLD are a dynamic nuclear domain since are induced by oleic acid (OA) by a reversible and coordinate mechanism with cLD; the process involves acyl-CoA synthetase (ACS) activity, TAG and CE biosynthesis and LD fusion and fission.L-FABP has an important role in nuclear FA mobilization. Exogenous FA, free or bound to L-FABP are incorporated into metabolic active nuclear lipids pools by an acyl-CoA pathway. Increasing concentrations of L-FABP determined a dose-dependent mobilization of nuclear and nLD oleic and arachidonic acid between TAG, CE, glycerophospholipids and FA as well as their release to the incubation medium. In conclusion, nLD would be involved in nuclear-lipid homeostasis and serve as an endonuclear buffering system that can provide or incorporate lipids and proteins involved in signaling paths, ligands for transcription factors and enzymes from lipid metabolism and nuclear processes. In particular, FA released by hydrolysis of nLD lipids, would bound to L-FABP in the nuclear matrix, mobilized to transcriptions factors as PPARs and participate in regulating lipid metabolism. Finally FA free and/or L-FABP bound would be release from the nucleus to the cytosol and involved in catabolic and /or anabolic pathways in different cellular compartments.