Abstract：Abstract The patatin like phospholipase domain-containing 3 (PNPLA3), also known as fat cell nutrients or calcium-independent phospholipase A2ε (iPLA2ε), is a member of the PNPLAs family. PNPLA3 has the activity of hydrolyzing phospholipids and neutral lipids and ester acyltransferase activity, and is able to participate in fat accumulation and fat mobilization. The objective of the present study is to investigate the characteristics of expression and regulation of PNPPLA3 in liver of chicken (Gallus gallus) and to pave the way for further elucidating the biological function of PNPLA3 gene in lipid metabolism of liver in chicken. The amino acid sequences of PNPLA3 in chicken and 12 other different species were retrieved from the genomic data bank using the Basic Local Alignment Search Tool (BLAST) homology search. Bioinformatic methods were used for phylogenetic and syntenic analysis. The qRT-PCR technique was used to analyze the temporal and spatial expression of PNPLA3 gene in different tissues of chicken. The regulatory mechanism of PNPLA3 gene was analyzed through stimulating juvenile hens in vivo, and chicken embryo hepatocytes treated with 17β-estradiol and estrogen receptor antagonists MPP, ICI182780 (fulvestrant) and ICI146474 (tamoxifen) in vitro. The results showed that the amino acid sequence similarity of PNPLA3 among chicken and amphibian and fish species was relatively higher than that among chicken and mammalian species. The PNPLA3 gene was extensively expressed in various tissues tested, in particular, the expression levels were higher in pectoral muscle, abdominal fat and pancreas in 10-week-old chicken, higher in liver, pectoral muscle, abdominal fat in 30-week-old chicken (P＜0.01). The 17β-estradiol treatment significantly increased the expression level of PNPLA3 in chicken liver tissue and primary hepatocytes (P＜0.05). The MPP, a specific antagonist of estrogen receptor ER-α, could completely inhibit the effect of 17β-estradiol on PNPLA3 expression (P＜0.05). Therefore, it is concluded that the similarity of the amino acid sequence of PNPLA3 is higher between chickens and amphibian and fish, however, it is lower to mammalian. PNPLA3 was abundantly expressed in liver tissue, and its expression level was significantly increased after maturation. The expression of PNPLA3 was regulated by estrogen, and the regulative effect was predominantly mediated via ER-α in liver of chicken. These findings lay the foundation for further understanding the regulation mechanism of fat metabolism in chicken.
