Nuclear Lipid Droplets have an active lipid metabolism

LAYERENZA, JUAN P; LAGRUTTA, LUCÍA C; SISTI, MARTÍN S; VES-LOSADA, ANA

Potrero de los Funes

Congreso; XLVII Reunión Anual de la SAIB; 2011

Sociedad Argentina de Bioquímica y Biología Molecular (SAIB)

Nuclear lipids have an active role in cell proliferation,differentiation and apoptosis. We have already determined thatnuclear lipids would have two main locations, the double nuclearmembrane (mainly composed of GPL, SPL and C) and the NuclearLipid Droplets (NLD: mainly composed of TAG, CE and C); both ofthem correspond to alternative lipid sources with different chemicalcomposition, physical properties, regulation and functions. We havealso demonstrated that nuclear matrices (where NLD are located)have a more active lipid metabolism than that of whole liver cellnuclei. Taking into account that nuclear oleic acid is mainlyesterified to TAG and CE, the aim of this work was to determine ifexogenous 18:1n-9 could be incorporated into NLD lipids. With thispurpose, rat liver isolated nuclei (N) were labeled in vitro with [1-14C]18:1n-9 and NLD were isolated after incubation. In NLD, [1-14C]18:1n-9 was incorporated as FFA and esterified inTAG>GPL>CE. Neither 18:1n-9 nor 16:0, 16:1n-7, 18:0 and 18:2n-6 were esterified to exogenous [4-14C]C, in spite of [4-14C]C beingincorporated into NLD. Exogenous C must have been incorporatedin an inadequate pool where it cannot be esterified.In conclusion, NLD have an active lipid metabolism sinceendogenous lipids FA can be remodeled. NLD oleic acid (TAG andCE) is a small cellular pool with a strategic localization.