Hepatic ELOVL6 mRNA is regulated by the gga-miR-22-3p in egg-laying hen

The elongation of very long chain fatty acids protein 6 (ELOVL6) encodes a fatty acid elongase that is responsible for the final step in endogenous saturated fatty acid synthesis and involves in de novo lipogenesis. Though the regulatory mechanism of ELOVL6 expression has been studied extensively, little is known about the role of miRNA in regulating ELOVL6 gene expression in chicken until now. To investigate the regulatory mechanism of miRNA on the expression of ELOVL6 gene, bioinformatics analysis was employed to predict the potential miRNAs that binding with the 3'untranslated region (3'UTR) of ELOVL6. The putative miRNA was further screened by comparative analysis with previous miRNA-seq results. Gga-miR-22-3p, which could bind with the 3'UTR of ELOVL6 and showed negative expression correlation with ELOVL6 gene in chicken liver, was obtained. Tissue expression profiles showed that gga-miR-22-3p and ELOVL6 are extensively expressed in many tissues, and ELOVL6 with high expression level in kidney and liver tissues, and gga-miR-22-3p with high expression in lung and heart. Dual-luciferase reporter assays results indicated that the expression of luciferase reporter gene linked with part sequence of the 3'UTR of chicken ELOVL6 gene was down-regulated by the overexpression of gga-miR-22-3p in the DF1 cells, and the down-regulation behavior was abolished when the gga-miR-22-3p binding site in 3'UTR of ELOVL6 was mutated (P > 0.05). Furthermore, the ELOVL6 expression in chicken hepatocytes was down-regulated when miR-22-3p was over-expressed. Therefore, we concluded that miR-22-3p might involve in controlling the hepatic lipid composition through affecting the expression of ELOVL6 gene, and could serve as a regulator of lipid metabolism in the liver of egg-laying hen.