Nuclear Lipid Droplets have an Active Lipid Metabolism

LAYERENZA, JUAN PABLO; LAGRUTTA, LUCÍA CAROLINA; SISTI, MARTÍN SEBASTIÁN; VES LOSADA, ANA

Potrero de los Funes

Congreso; XLVII Reunión Anual de SAIB; 2011

SAIB

Nuclear lipids have an active role in cell proliferation, differentiation and apoptosis. We have already determined that nuclear lipids would have two main locations, the double nuclear membrane (mainly composed of GPL, SPL and C) and the Nuclear Lipid Droplets (mainly composed of TAG, CE and C); both of them correspond to alternative lipid sources with different chemical composition, physical properties, regulation and functions.We have also demonstrated that nuclear matrices (where NLD are located) have a more active lipid metabolism than that of whole liver cell nuclei. Taking into account that nuclear oleic acid is mainly esterified to TAG and CE, the aim of this work was to determine if exogenous 18:1n-9 could be incorporated into NLD lipids.  With this purpose, 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 in TAG > 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 [14C]C being incorporated into NLD.  Exogenous C must have been incorporated in an inadequate pool where it cannot be esterified.In conclusion, NLD have an active lipid metabolism since endogenous lipids FA can be remodeled. NLD oleic acid (TAG and CE) is a small cellular pool with a strategic localization.