Abstract
Background: Lipid metabolism is closely associated with various metabolic diseases, such as obesity, cardiovascular disease, diabetes, and cancer. More importantly, it also affects the carcass quality of animals. Angiopoietin-like protein (Angiopoietin-like, ANGPTL) family members are encoded by 8 genes and play an important role in lipid metabolism and angiogenesis. In this study, we first systematically described the phylogenetic characteristics of pig ANGPTL family genes and identified the critical roles of ANGPTL3, ANGPTL4 and ANGPTL8 in the lipid metabolism of pigs.Methods: The amino acid sequence analysis, phylogenetic analysis, and chromosome adjacent gene analysis were performed to identify the ANGPTL gene family in pigs. Furthermore, according to the body weight data from 60 Jinhua pigs, different tissues of 6 pigs with average body weight were used to determine the expression profile of ANGPTL1-8. The ileum, subcutaneous fat, and liver of 8 pigs with distinct fatness were selected to analyze the gene expression of ANGPTL3, ANGPTL4, and ANGPTL8. Results: Results showed the sequence length of ANGPTLs in pigs was between 1186 and 1991 bp, and the pig ANGPTL family members shared common features with human homologous genes, including the high similarity of the amino acid sequence and chromosome flanking genes. Amino acid sequence analysis showed that ANGPTL1-7 had a highly conserved domain except for ANGPTL8. Phylogenetic analysis showed that the ANGPTL homologues identified from 6 species could be divided into two categories. Each ANGPTL homologous gene was clustered with other mammalian sequences, away from other vertebrates. RT-qPCR analysis showed that ANGPTL family members had different expression patterns in different tissues. ANGPTL3 and ANGPTL8 were mainly expressed in the liver, while ANGPTL4 was expressed in many other tissues, such as the intestine and subcutaneous fat. The expression levels of ANGPTL3 and ANGPTL4 in Jinhua pigs with low propensity for adipogenesis were significantly higher than those of high propensity for adipogenesis. Conclusions: These results increase our knowledge about the biological role of the ANGPTL family in this important economic species. In addition, it will also help to better understand the role of ANGPTL3, ANGPTL4 and ANGPTL8 in lipid metabolism of pigs, and provide innovative ideas for develop strategies to improve pig carcass quality.