Role of peroxisomal oxidation in the conversion of arachidonic acid to eicosatrienoic acid in human skin fibroblasts.
Human skin fibroblasts converted [5,6,8,9,11,12,14,15-3H]arachidonic acid ([3H]20:4) to eicosatrienoic acid (20:3), but appreciable amounts of radiolabeled 20:3 were not detected in corresponding incubations with [1-(14)C]20:4. This indicates that the main pathway for synthesizing 20:3 from arachidonic acid in the fibroblast involves oxidative removal of the carboxyl group of arachidonic acid. Fibroblasts deficient in long-chain acyl coenzyme A dehydrogenase (LCAD) converted [3H]20:4 to [3H]20:3. However, Zellweger fibroblasts that are deficient in peroxisomal fatty acid oxidation did not, indicating that the oxidative removal of the carboxyl group occurs in the peroxisomes. [3H]Hexadecatrienoic acid (16:3) was the main product that accumulated when [3H]20:4 was incubated with normal, LCAD deficient, and very long-chain acyl coenzyme A dehydrogenase (VLCAD) deficient fibroblasts, but Zellweger fibroblasts did not form this product. Normal fibroblasts converted [3H]16:3 to radiolabeled 20:3 and arachidonic acid. These findings suggest that some of the 16:3 produced from arachidonic acid by peroxisomal beta-oxidation can be recycled and that this recycling process constitutes a novel pathway for the conversion of arachidonic acid to 20:3 in human fibroblasts.
Spector
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Department of Biochemistry, University of Iowa, Iowa City 52242, USA. arthur-spector@uiowa.edu
Willard
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Kaduce
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Widstrom
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D015126:8,11,14-Eicosatrienoic Acid / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism*; D002460:Cell Line; D003470:Culture Media; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D015227:Lipid Peroxidation; D020675:Peroxisomes / Q000378:metabolism / Q000502:physiology*; D012867:Skin / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D014316:Tritium / Q000032:analysis / Q000378:metabolism
D003470:Culture Media; D005227:Fatty Acids; D014316:Tritium; D016718:Arachidonic Acid; D015126:8,11,14-Eicosatrienoic Acid