Incorporation of delta 5 desaturase substrate (dihomogammalinolenic acid, 20:3 n-6) and product (arachidonic acid 20:4 n-6) into rat liver cell nuclei.
The incorporation of [1-(14)C]20:3 n-6 and its desaturation product, [1-(14)C]20:4 n-6 into nuclear lipids from rat liver cells were investigated during in vitro delta5 desaturation. [1-(14)C]20:3 n-6 activated as 20:3 n-6-CoA by nuclear long chain acyl-CoA synthetase was: (1) incorporated into nuclear lipids mainly esterified to phospholipids and in a lesser proportion, to triglycerides and diglycerides; and (2) desaturated to 20:4 n-6-CoA by the nuclear delta5 desaturase. The amount of [1-(14)C]20:4 n-6 acid synthesized in cell nuclei increased along with time and was stimulated by the cytosol fraction. The major proportion of 20:4 n-6 was found in phospholipids and in a lesser proportion it remained as free fatty acids and was esterified to triglycerides and diglycerides. 20:4 n-6-CoA was incorporated into nuclear lipids and hydrolyzed to free fatty acid. These results indicate that liver cell nuclei possess the necessary enzymes to incorporate the delta5 desaturase substrate (20:3 n-6) as well as the product of desaturation (20:4 n-6) into nuclear TG, DG and PL following an acyl-CoA dependent pathway.
Ves Losada
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A
Dto de Cs. Biológicas, Facultad de Cs. Exactas, UNLP, Argentina. avlosada@biolp.edu.ar
Brenner
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RR
D015126:8,11,14-Eicosatrienoic Acid / Q000378:metabolism*; D044942:Acyl-CoA Dehydrogenase, Long-Chain / Q000378:metabolism*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000378:metabolism; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D000090943:Delta-5 Fatty Acid Desaturase; D044943:Fatty Acid Desaturases; D050356:Lipid Metabolism; D008099:Liver / Q000166:cytology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D002250:Carbon Radioisotopes; D000090943:Delta-5 Fatty Acid Desaturase; D016718:Arachidonic Acid; D044943:Fatty Acid Desaturases; D044942:Acyl-CoA Dehydrogenase, Long-Chain; D015126:8,11,14-Eicosatrienoic Acid