Expression Profile and Regulatory Properties of m6A-Modified circRNAs in the Longissimus Dorsi of Queshan Black and Large White Pigs

SIMPLE SUMMARY: With the improvement of living standards, people have higher requirements for pork quality. Intramuscular fat is among the important factors that determine the quality of pork, affecting the taste and flavor. Producing quality meat with high intramuscular fat content has been a major challenge for China’s livestock industry. In addition, m6A modification is abundant in many circRNAs, and m6A-circRNAs play an important regulatory role in a variety of biological processes. In this study, a total of 12 putative m6A-circRNAs were identified, their potential molecular regulatory mechanisms on fat deposition and meat quality in Chinese and Western pigs were explored through a series of bioinformatics analyses, which laid a foundation for further elucidations of the functions of m6A-circRNAs in fat deposition and growth and development of pigs. ABSTRACT: It is well known that N6-methyladenosine (m6A) is the most abundant modification in linear RNA molecules, but many circRNA molecules have now been found to have a wide range of m6A modification sites as well. However, there are few relevant studies and information on the expression profile and functional regulatory properties of m6A-modified circRNAs (m6A-circRNAs) in longissimus dorsi. In this study, a total of 12 putative m6A-circRNAs were identified and characterized in the longissimus dorsi of Queshan Black and Large White pigs—8 of them were significantly more expressed in the longissimus dorsi of Queshan Black than in Large White pigs, while the other 4 were the opposite. These 12 putative m6A-circRNAs were also found to act as miRNA sponge molecules to regulate fat deposition by constructing the ceRNA regulatory network. Enrichment analysis also revealed that the 12 m6A-circRNAs parent genes and their adsorbed miRNA target genes were widely involved in fat deposition and cell proliferation and differentiation-related pathways, such as the HIF-1 signaling pathway, the pentose phosphate pathway, the MAPK signaling pathway, the glycosphingolipid biosynthesis-lacto and neolacto series, and the TNF signaling pathway, suggesting that the analyzed m6A-circRNAs may be largely involved in the formation of pork quality. These results provide new information to study the regulatory properties of m6A-circRNAs in the formation of pork quality.