ROLE OF L-FABP ON THE INCORPORATION OF SATURATED AND POLYUNSATURATED FATTY ACIDS IN ENDONUCLEAR LIPID POOLS

MATÉ, SABINA M.; BRENNER, RODOLFO R.; VES-LOSADA, ANA

San Carlos de Bariloche, Río Negro

Congreso; XXXIX Reunión Anual de SAIB, XXXII Reunión Anual de SAB y Primer Simposio Latinoamericano de Proteínas; 2003

SAIB y SAB

Our aim was to study the role of L-FABP on the trafficking of fatty acids from cytosol to nuclear lipid pools where they regulate the expression of certain genes. Nuclei and nuclear matrix (Mx: nuclei without membrane) of rat liver cells were incubated in vitro with [1-14C]18:0 and [1-14C]20:n-6, either free or bound to the L-FABP. Incorporation and esterification of 18:0 and 20:4n-6 were carried out in nuclear and endonuclear lipid pools. We observed that the incorporated total radioactivity was not modified by the L-FABP. Firstly, [1-14C]18:0 and [1-14C]20:4n-6 were incorporated into FFA>PL>>TAG (in the presence of ATP and CoA). Then, [1-14C]fatty acid incorporated was decreased in FFA, increased in TAG, and saturated in PL, with the incubation time. In endonuclear pools (Mx) 18:0 and 20:4n-6 bound to L-FABP were incorporated, showing a greater proportion in DAG and PI, respectively. In conclusion, 18:0 and 20:4n-6, exogenous, free or bound to L-FABP,are incorporated into total nuclear and endonuclear lipid pools through an acyl-CoA pathway. L-FABP does not affect nuclear FA uptake, but estimulates the FA esterification, directing the fatty acids into specific lipid fractions.