The Important Role of m6A-Modified circRNAs in the Differentiation of Intramuscular Adipocytes in Goats Based on MeRIP Sequencing Analysis.

Intramuscular fat contributes to the improvement of goat meat quality. N6-Methyladenosine (m6A)-modified circular RNAs play important roles in adipocyte differentiation and metabolism. However, the mechanisms by which m6A modifies circRNA before and after differentiation of goat intramuscular adipocytes remain poorly understood. Here, we performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) and circRNA sequencing (circRNA-seq) to determine the distinctions in m6A-methylated circRNAs during goat adipocyte differentiation. The profile of m6A-circRNA showed a total of 427 m6A peaks within 403 circRNAs in the intramuscular preadipocytes group, and 428 peaks within 401 circRNAs in the mature adipocytes group. Compared with the intramuscular preadipocytes group, 75 peaks within 75 circRNAs were significantly different in the mature adipocytes group. Furthermore, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of intramuscular preadipocytes and mature adipocytes showed that the differentially m6A-modified circRNAs were enriched in the PKG signaling pathway, endocrine and other factor-regulated calcium reabsorption, lysine degradation, etc. m6A-circRNA-miRNA-mRNA interaction networks predicted the potential m6A-circRNA regulation mechanism in different goat adipocytes. Our results indicate that there is a complicated regulatory relationship between the 12 upregulated and 7 downregulated m6A-circRNAs through 14 and 11 miRNA mediated pathways, respectively. In addition, co-analysis revealed a positive association between m6A abundance and levels of circRNA expression, such as expression levels of circRNA_0873 and circRNA_1161, which showed that m6A may play a vital role in modulating circRNA expression during goat adipocyte differentiation. These results would provide novel information for elucidating the biological functions and regulatory characteristics of m6A-circRNAs in intramuscular adipocyte differentiation and could be helpful for further molecular breeding to improve meat quality in goats.

ACADL Promotes the Differentiation of Goat Intramuscular Adipocytes.

Intramuscular fat (IMF) deposits help improve meat quality such as marbling, juicy, flavor and tenderness. Long-chain acyl-CoA dehydrogenase (ACADL) is a key enzyme for catalyzing fatty acid oxidation, and studies have shown ACADL is involved in the deposition and differentiation of intramuscular adipocytes. However, the effect of ACADL on intramuscular adipocytes differentiation in goats needs further study. In this study, to explore the mechanism of ACADL on the development of goat intramuscular adipocytes, we constructed an over-expression plasmids and a SI-RNA of ACADL to explore the function of ACADL on the development of goat IMF. It was found that overexpression of ACADL promoted the differentiation of goat intramuscular adipocytes, and promoted the expression of fat cell differentiation marker genes lipoprotein lipase (LPL), peroxisome proliferator activated receptor gamma (PPARγ), APETALA-2-like transcription factor gene (AP2), CCAT enhancer binding protein (CEBPα), preadipocyte Factor 1 (Pref-1) and CCAT enhancer binding protein (CEBPß), and the opposite trend occurred after interference. In addition, we screened of this related tumor necrosis factor (TNF) signaling pathway by RNA-Seq. So, we validate the signaling pathway with inhibitor of TNF signaling pathway. In summary, these results indicate that ACADL promotes intramuscular adipocytes differentiation through activation TNF signaling pathway. This study provides an important basis for the mechanism of IMF development.

Goat miR-92a-3p Targets APOL6 Gene to Regulate the Differentiation of Intramuscular Precursor Adipocytes.

The quality of lamb meat is positively correlated with intramuscular fat content. In recent years, a large number of studies have shown that miRNAs play an important role in the proliferation and differentiation of adipocytes. In this study, we aimed to explore the effect of miR-92a-3p on the differentiation of goat intramuscular preadipocytes. The results showed that the expression level of miR-92a-3p was low in the early stage of differentiation, reached the highest level on the third day of differentiation, and then decreased. And miR-92a-3p can inhibit the accumulation of lipid droplets and down-regulate the determinants of adipogenic differentiation. Mechanistically, by predicting target genes, we found that miR-92a-3p affects the differentiation of goat intramuscular preadipocytes and the accumulation of lipid droplets by regulating the expression of goat gene APOL6. This study provides important new information to better understand the relationship between miRNAs and the differentiation of goat intramuscular preadipocytes, thus providing a new reference for goat intramuscular adipogenesis.