Metabolism and functions of highly unsaturated fatty acids: An update

• Published in: Lipids Vol. 36; no. 9; pp. 961 - 964
• Main Authors: Nakamura, Manabu T., Cho, Hyekyung P., Xu, Jing, Tang, Zhongren, Clarke, Steven D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer‐Verlag 01.09.2001; Springer Nature B.V
• Subjects: Animals; Cloning; Diet; Fatty Acid Desaturases - genetics; Fatty Acid Desaturases - metabolism; Fatty acids; Fatty Acids, Unsaturated - metabolism; Fatty Acids, Unsaturated - pharmacology; Fatty Acids, Unsaturated - physiology; Gene expression; Humans; Linoleoyl-CoA Desaturase; Nutrition; Oxidation-Reduction; Peroxisome Proliferators - metabolism
• ISSN: 0024-4201; 1558-9307
• DOI: 10.1007/s11745-001-0806-5

This review briefly examines the recent progress in knowledge about the synthesis and degradation of highly unsaturated fatty acids (HUFA) and their functions. Following the cloning of mammalian Δ6‐desaturase (D6D), the D6D mRNA was found in many tissues, including adult brain, maternal organs, and fetal tissue, suggesting an active synthesis of HUFA in these tissues. The cloning also confirmed the long‐postulated hypothesis that the same pathway is followed in n−6 and n−3 HUFA synthesis. Dietary n−6 and n−3 HUFA both induce fatty acid oxidation enzymes in peroxisomes when compared to their respective precursor polyunsaturated fatty acids. This suggests that peroxisomes may be the primary site of HUFA degradation when HUFA are supplied in excess from the diet. Peroxisome proliferators strongly induce the enzymes for the HUFA synthesis. The mechanism of this induction is currently unknown. Recent studies revealed new HUFA functions that are not mediated by eicosanoids. These functions include endocytosis/exocytosis, ionchannel modulation, DNA polymerase inhibition, and regulation of gene expression. These new discoveries will enable us to reexamine the underlying mechanisms for the classical symptoms of essential fatty acid deficiency as well as vitamin E deficiency. Progress has also been made in understanding the mechanism by which dietary HUFA reduce body fat deposition. One mechanism is induction of genes for fatty acid oxidation, which is mediated by peroxisome proliferator‐activated receptor‐α. Another likely mechanism is that HUFA suppress genes for fatty acid synthesis by reducing both mRNA and protein maturation of sterol regulatory element binding protein‐1.