Nuclear Lipid Droplets have an dinamic metabolism

LAGRUTTA LC; LAYERENZA JP; MONTERO VILLEGAS S; SISTI MS; GARCIA MARGARITA; VES-LOSADA A

Puerto Iguazú

Congreso; 56th International Conference on the Bioscience of Lipids; 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 also a dynamic nuclear domain since they are induced by oleic acid (OA) by means of a reversible and coordinating mechanism with cytosolic LD (cLD); this process involves acyl-CoA synthetase (ACSL) activity, TAG and CE biosynthesis, and LO fusion and fission. Liver Fatty Acid Binding Protein (L-FABP) has an important role in nuclear fatty acid (FA) mobilization. Exogenous FA, free or L-FABP bound, 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 nudear-lipid homeostasis and serve as an endonuclear buffering system. nLD 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 bind to L-FABP in the nuclear matrix, mobilize to transcriptions factors as PPARs, and participate in regulating lipid metabolism. Finally, FA free and/or L-FABP bound would be released from the nucleus to the cytosol and involved in catabolic and/or anabolic pathways in different cellular compartments