Delta-6-desaturase and delta-5-desaturase in human Hep G2 cells are both fatty acid interconversion rate limiting and are upregulated under essential fatty acid deficient conditions

T Melin, A Nilsson

Research output: Contribution to journalArticlepeer-review

Abstract

Essential fatty acids are interconverted by desaturases and elongases to eicosanoid precursors. In essential fatty acid deficiency (EFAD) an increased hepatic interconversion of linoleic acid (18:2) to arachidonic acid (20:4n-6) has been demonstrated in vivo. We now cultured Hep G2 cells under EFAD conditions. 20:3n-6 appeared in EFAD cells, but also in controls. After adding 14C-18:2 to the medium, interconversion products and their distribution in different lipids were studied by HPLC. When trace amounts 18:2 were incubated, 38% were converted by the EFAD cells after 21 h, vs 6% by controls. 20% was converted to 20:4 by EFAD cells vs 14% by controls. EFAD cells preferentially distributed more 18:2 and conversion products to neutral fats and to phosphatidyl ethanolamine, but less to cardiolipin than controls did, when incubated with trace amount 18:2, but not with 1 mM 18:2. A relative accumulation of radioactivity in 20:3 was observed. In conclusion; in EFAD Hep G2 cells delta-6- and delta-5-desaturase both were found to be upregulated and eicosanoid precursors were distributed more into phosphatidyl ethanolamine. Delta-5-desaturase had a rate limiting property as well as delta-6-desaturase.

Original languageEnglish
Pages (from-to)437-42
Number of pages6
JournalProstaglandins, Leukotrienes and Essential Fatty Acids
Volume56
Issue number6
DOIs
Publication statusPublished - 1997 Jun
Externally publishedYes

Subject classification (UKÄ)

  • Cell and Molecular Biology

Free keywords

  • Arachidonic Acid/metabolism
  • Cell Line
  • Fatty Acid Desaturases/metabolism
  • Fatty Acids/metabolism
  • Fatty Acids, Essential/deficiency
  • Humans
  • Kinetics
  • Linoleic Acid
  • Linoleic Acids/metabolism
  • Linoleoyl-CoA Desaturase
  • Phospholipids/metabolism
  • Up-Regulation

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