L-FABP shuttles 20:4n-6 in nuclear lipid pools

CATTÁNEO, E.R., BRENNER, RODOLFO R. Y VES-LOSADA, ANA

Pinamar, Buenos Aires

Congreso; XLI Reunión Anual de SAIB y X Congreso PABMB; 2005

SAIB y PABMB

Regulation of gene expression by fatty acids is an event that takes place inside the nuclei of eukaryotic cells. Fatty acids regulate the gene expression of enzymes involved in lipid and glucose metabolism, in adipogenesis process, and in cell differentiation. Due to their hydrophobic nature and poor water solubility, fatty acids move within the cells bound to L-FABP. Our aim was to study the role of L-FABP in the trafficking of nuclear fatty acids. Thus, nuclear 20:4n-6 pools were labeled by  in vitro incubation of nuclei isolated from rat liver cells with [1-14C]20:4n-6, in presence of ATP and CoA. Then, these control nuclei were reincubated without 20:4n-6, plus ATP, CoA and L-FABP. In control nuclei [1-14C]20:4n-6 was incorporated into PL (54%), FFA (26%) and TG (20%). In PL it was esterified in PC (58%), PE (29%) and PI (13%). In reincubated nuclei we observed that 20:4n-6: 1)increased in the incubation medium and 2)in nuclear pools, decreased as FFA and increased in PI, as a function of L-FABP concentration. Reincubation conditions were repeated using BSA as a carrier protein control. In conclusion, L-FABP movilizes nuclear arachidonic acid, since it removes 20:4n-6 from nuclear pools and directs it to PI.