[1- 14C]20:4 n-6 ACID IS INCORPORATED INTO THE INNER AND OUTER NUCLEAR MEMBRANE OF RAT LIVER CELL

MATÉ, SABINA M. 1.; BRENNER, RODOLFO R. 1.; VES-LOSADA, ANA 1,2.

Posadas, Misiones, Argentina.

Congreso; XXXX SAIB; 2004

SAIB

[1- 14C]20:4 n-6 ACID IS INCORPORATED INTO THE INNER AND OUTER NUCLEAR MEMBRANE OF RAT LIVER CELLMaté, Sabina M. 1 ; Brenner, Rodolfo R. 1 and Ves-Losada, Ana 1,2 . 1 INIBIOLP, Facultad de Ciencias Médicas, UNLP, calles 60 y 120, 1900, La Plata.2 Facultad de Ciencias Exactas, UNLP. The aim of this work was to determine if arachidonic acid (20:4n-6) is incorporated into inner (IM) and outer (OM) nuclear membranes of rat liver cell nuclei during its trafficking from cytosol to nuclear pools. This acid regulates the expression of certain genes in the nucleus. For this reason,  IM and OM were separated from isolated nuclei of rat liver cells. OM was solubilized using sodium citrate, and the resulting nucleopast was digested with DNase 1. Membranes were recovered by centrifugation in a sucrose discontinuous gradient. Then IM and OM were incubated in vitro with [1-14C]20:4n-6, and 20:4n-6 incorporation was assessed in the lipid pools. It was noted that [1-14C]20:4n-6 acid was mainly esterified in PL of nuclear IM and OM in the presence of ATP and CoA. In both membranes, the acid incorporation takes place in PtdCho > PtdEtn > PtdIns. Incorporated radioactivity increased in PtdCho and decreased in PtdIns and PtdEtn with the incubation time. In conclusion, exogenous 20:4n-6 acid is mainly esterified in PtdCho of  IM and OM isolated from rat liver cell nuclei through an acyl-CoA-dependent process. The incorporation mechanisms in both membranes would be independent each other.