Incorporation of Arachidonic and Stearic Acids Bound to L-FABP into Nuclear and Endonuclear Lipids from Rat Liver Cells |
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Authors: | Sabina M. Maté Juan P. Layerenza Ana Ves-Losada |
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Affiliation: | Facultad de Ciencias Médicas, Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET-UNLP, 60 y 120, 1900 La Plata, Argentina. |
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Abstract: | 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. |
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Keywords: | Cell nuclei Nuclear matrix Endonuclear lipids Arachidonic acid Stearic acid Fatty acid incorporation L-FABP |
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