Investigation of ANGPTL3 expression, exon sequence and promotor methylation between Ningxiang and Changbai pigs

Background: Angiopoietin-like protein 3 (ANGPTL3), a member of angiopoietin-like proteins, has been demonstrated to affect lipid metabolism by inhibiting the activity of lipoprotein lipase (LPL).
Objective: To compare the ANGPTL3 mRNA and protein expression, exon mutation and promoter district CpG island methylation state between Ningxiang Pigs and Changbai Pigs.
Methods: Pigs were slaughtered and about 100 mg of tissue samples and subcutaneous adipose tissue were collected and stored for analysis. Quantitative Real-Time PCR, Western blotting, exons sequencing, and HRM analysis were carried out.
Results: ANGPTL3 was expressed in liver but not in fat and lean meat. Compared with Changbai pigs, ANGPTL3 mRNA level in Ningxiang pigs was lower. However, the protein expression showed no difference between these two groups of pigs. Sequences analysis showed that four variations existed between Changbai Pigs and Ningxiang Pigs, among which three variations caused no change of amino acids, and the other one caused amino acid mutation from Val (Changbai) to Met (Ningxiang). The ANGPTL3 promoter district CpG island bisulfite-PCR and sequencing results showed that the mean methylation rate ranged from 70.952% to 95.238% between Changbai pig and Ningxiang pig (p<0.05).
Conclusion: These results support the significant difference (p<0.05) between Changbai pig and Ningxiang pig in highresolution melting (HRM) analysis. All these results may be helpful for a better understanding of the role of ANGPTL3 in lipid metabolism.