Saturated and monounsaturated fatty acids in membranes are determined by the gene expression of their metabolizing enzymes SCD1 and ELOVL6 regulated by the intake of dietary fat

Ralph Rühl,Kathrin Weiss-Hersh,Tamás Marosvölgyi,Ada L. Garcia,Tamás Decsi,Mónika Szklenár

doi:10.1007/s00394-019-02121-2

Ralph Rühl, Kathrin Weiss-Hersh + Show 4 more

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https://doi.org/10.1007/s00394-019-02121-2

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Abstract

PurposeWe investigated the effect of dietary fats on the incorporation of saturated (SAFAs) and monounsaturated dietary fatty acids (MUFAs) into plasma phospholipids and the regulation of the expression of lipid-metabolizing enzymes in the liver.MethodsMice were fed different diets containing commonly used dietary fats/oils (coconut fat, margarine, fish oil, sunflower oil, or olive oil) for 4 weeks (n = 6 per diet group). In a second experiment, mice (n = 6 per group) were treated for 7 days with synthetic ligands to activate specific nuclear hormone receptors (NHRs) and the hepatic gene expression of CYP26A1 was investigated. Hepatic gene expression of stearoyl-coenzyme A desaturase 1 (SCD1), elongase 6 (ELOVL6), and CYP26A1 was examined using quantitative real-time PCR (QRT-PCR). Fatty acid composition in mouse plasma phospholipids was analyzed by gas chromatography (GC).ResultsWe found significantly reduced hepatic gene expression of SCD1 and ELOVL6 after the fish oil diet compared with the other diets. This resulted in reduced enzyme-specific fatty acid ratios, e.g., 18:1n9/18:0 for SCD1 and 18:0/16:0 and 18:1n7/16:1n7 for ELOVL6 in plasma phospholipids. Furthermore, CYP26A1 a retinoic acid receptor-specific target was revealed as a new player mediating the suppressive effect of fish oil-supplemented diet on SCD1 and ELOVL6 hepatic gene expression.ConclusionPlasma levels of MUFAs and SAFAs strongly reflect an altered hepatic fatty acid-metabolizing enzyme expression after supplementation with different dietary fats/oils.

Highlights

Fatty acids of nutritional relevance can be grouped as saturated fatty acids (SAFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs)
These fatty acids are found in commonly consumed dietary fats such as coconut fat, rich in SAFAs; olive oil, rich in MUFAs [mainly oleic acid (OLA, 18:1n9)]; fish oil, rich in n3-PUFAs [mainly eicosapentaenoic acid (EPA, 20:5n3) and docosahexaenoic acid (DHA, 22:6n3)]; sunflower oil, rich in n6-PUFAs [mainly linoleic acid (LA, 18:2n6)]; and margarine, a mix of n6-PUFAs, MUFAs, and SAFAs
Fatty acid comparisons between all diet groups showed that the highest amount of 16:0 was found in the margarine diet, while the lowest amount was measured in the sunflower oil diet (Fig. 1a)

Summary

Introduction

Fatty acids of nutritional relevance can be grouped as saturated fatty acids (SAFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). High intake of n6-PUFAs results in a shift of the n3/n6 PUFA ratio towards a more pronounced n6-PUFAs ratio, which has been associated with the pathogenesis of various chronic inflammatory diseases [4]. Another alternative to reduce SAFA intake is consumption of margarine with a higher PUFAs’ and MUFAs’ content; the benefits of margarine consumption are not conclusive [5,6,7]. A better understanding of the roles fatty acids play on mechanisms underpinning health and disease is needed

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