Incorporation of arachidonic and stearic acids bound to L-FABP into nuclear and endonuclear lipids from rat liver cells.
The incorporation of exogenous fatty acids bound to L-FABP into nuclei was studied. Rat liver cell nuclei and nuclear matrices (membrane depleted nuclei) were incubated in vitro with [1-(14)C]18:0 and 20:4n-6 either free or bound to L-FABP, ATP and CoA. FA esterification in whole nuclei and endonuclear lipids was ATP-CoA-dependent, and with specificity regarding fatty acid type and lipid class. 18:0 and 20:4n-6, free or L-FABP bound, showed the same incorporation and esterification pattern in lipids of whole nuclei. Only 20:4n-6 L-FABP bound was less incorporated into TAG with respect to free 20:4n-6. In the nuclear matrix, 18:0 free or L-FABP bound was esterified with a higher specific activity (SA) into: PtdEtn > PtdIns, PtdSer > PtdCho. 20:4n-6 free or L-FABP bound was esterified into: PtdIns > PtdEtn > PtdCho. 20:4n-6:L-FABP was esterified in endonuclear total-PL and PtdIns with a greater SA with respect to free 20:4n-6 and with a minor one as FFA. To summarize, trafficking of FA to nuclei includes esterification of 18:0 and 20:4n-6 either free or L-FABP-bound, into nuclear and endonuclear lipids by an ATP-CoA-dependent pathway. Endonuclear fatty acid esterification was more active than that in whole nuclei, and independent of the nuclear membrane. Esterification patterns of fatty acids L-FABP-bound or free into whole nuclear lipids were the same whereas in the nuclear matrix, L-FABP could play an important role in the mobilization of 20:4n-6 into specific sites of utilization such as the PtdIns pools.
Maté
Sabina M
SM
Facultad de Ciencias Médicas, Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET-UNLP, 60 y 120, 1900 La Plata, Argentina.
Layerenza
Juan P
JP
Ves-Losada
Ana
A
D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D002247:Carbon Isotopes / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure*; D004951:Esterification; D050556:Fatty Acid-Binding Proteins / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism* / Q000648:ultrastructure; D050356:Lipid Metabolism; D008099:Liver / Q000166:cytology; D008297:Male; D015530:Nuclear Matrix / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D013229:Stearic Acids / Q000378:metabolism*
D000214:Acyl Coenzyme A; D001095:Arachidonic Acids; D002247:Carbon Isotopes; C493321:Fabp1 protein, rat; D050556:Fatty Acid-Binding Proteins; D010716:Phosphatidylinositols; D013229:Stearic Acids