Regulation of chicken vanin1 gene expression by peroxisome proliferators activated receptor α and miRNA-181a-5p

Abstract

Objective: Vanin1 (VNN1) is a pantetheinase that can catalyze the hydrolysis of pantetheine to produce pantothenic acid and cysteamine. Our previous studies showed that <i>VNN1</i> is specifically expressed in chicken liver. In this study, we aimed to investigate the roles of peroxisome proliferators activated receptor α (PPARα) and miRNA-181a-5p in regulating <i>VNN1</i> gene expression in chicken liver.Methods: 5′-RACE was performed to identify the transcription start site of chicken <i>VNN1</i>. JASPAR and TFSEARCH were used to analyze the potential transcription factor binding sites in the promoter region of chicken <i>VNN1</i> and miRanda was used to search miRNA binding sites in 3′ untranslated region (3′UTR) of chicken <i>VNN1</i>. We used a knock-down strategy to manipulate PPARα (or miRNA-181a-5p) expression levels <i>in vitro</i> to further investigate its effect on <i>VNN1</i> gene transcription. Luciferase reporter assays were used to explore the specific regions of VNN1 targeted by PPARα and miRNA-181a-5p.Results: Sequence analysis of the VNN1 promoter region revealed several transcription factor-binding sites, including hepatocyte nuclear factor 1α (HNF1α), PPARα, and CCAAT/enhancer binding protein α. GW7647 (a specific agonist of PPARα) increased the expression level of <i>VNN1</i> mRNA in chicken primary hepatocytes, whereas knockdown of PPARα with siRNA increased VNN1 mRNA expression. Moreover, the predicted PPARα-binding site was confirmed to be necessary for PPARα regulation of <i>VNN1</i> gene expression. In addition, the <i>VNN1</i> 3′UTR contains a sequence that is completely complementary to nucleotides 1 to 7 of miRNA-181a-5p. Overexpression of miR-181a-5p significantly decreased the expression level of <i>VNN1</i> mRNA.Conclusion: This study demonstrates that PPARα is an important transcriptional activator of <i>VNN1</i> gene expression and that miRNA-181a-5p acts as a negative regulator of <i>VNN1</i> expression in chicken hepatocytes.