Abstract
The very long chain fatty acid elongase (ELOVL) plays an important role in the synthesis of long-chain polyunsaturated fatty acids (LCPUFA). Previous studies suggest that chicken could be an alternate source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In this study, we detected that ELOVL5, which plays a key role in the biosynthesis of omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFA), was highly expressed in the liver of laying hens and increased rapidly after sexual maturity. Bioinformatic analysis revealed ELOVL fatty acid elongase 5 (ELOVL5) gene as a putative target of miR-218-5p, miR-19a-3p, miR-19b-3p, miR-30a-5p, miR-30b-5p, and miR-30e-5p. We demonstrated estrogen downregulated microRNA (miRNA), and that ELOVL5 is a direct target of miR-218-5p, which was located in intron 14 of the Slit guidance ligand 2 (SLIT2) gene and co-expressed with the host gene. Overall, estrogen enhanced hepatic synthesis of LCPUFA by functioning as a negative regulator of miRNA thereby augmenting the expression of these miRNA target genes, especially ELOVL5, which plays a key role in the biosynthesis of n-3 and n-6 LCPUFA. This study provides a novel model for the use of estrogen in the poultry industry as an inducer of ELOVL5 expression to enhance hepatic n-3 and n-6 LCPUFA synthesis at the post-transcriptional level.
Highlights
Fish and fish oil are the most common dietary sources of omega-3 (n-3) long-chain polyunsaturated fatty acids (LCPUFA), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [1,2,3]
Previous studies suggested that compared with other species, the chicken ELOVL5 enzyme has a five-fold conversion rate from docosapentaenoic acid (DPA) (22:5n-3) to 24:5n-3, which is the penultimate precursor of DHA [1,6]
To investigate the effect of estradiol on the synthesis of long-chain polyunsaturated fatty acids, we focused on ELOVL5, which plays a key role in the biosynthesis of PUFA
Summary
Fish and fish oil are the most common dietary sources of omega-3 (n-3) long-chain polyunsaturated fatty acids (LCPUFA), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [1,2,3]. Previous studies suggested that compared with other species, the chicken ELOVL5 enzyme has a five-fold conversion rate from DPA (22:5n-3) to 24:5n-3, which is the penultimate precursor of DHA [1,6]. The liver plays a central role in whole-body lipid metabolism, which encompasses the synthesis and modification of fatty acids by way of desaturation, elongation, and oxidation [7]. These key enzymes of fatty acid metabolism are highly expressed in the liver, and their activities and expression are regulated during development by diet, hormones, and other factors, in mature animals [9].
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