Circular RNA Profiling Identifies Novel circPPARA that Promotes Intramuscular Fat Deposition in Pigs br

Intramuscular fat (IMF) content plays an important role in pork quality. Circular RNAs (circRNAs) implicate variousbiological processes; however, the regulatory mechanisms and functions of circRNAs in porcine IMF remains elusive. Hence, thestudy assessed the circRNA expression profiling in the longissimus dorsi muscle of pigs with high (H) and low (L) IMF content tounravel their regulatory functions in improving meat quality. The RNA sequencing analysis identified 29,732 circRNAs from sixsampled pigs, most of which were exon-derived. In the muscle, 336 were differentially expressed (DE) between the H and L IMFgroups; 196 circRNAs were upregulated, and 140 were downregulated. Subsequent qRT-PCR validation of 10 DE circRNAsrevealed expression patterns consistent with the RNA-seq data. Gene ontology and KEGG enrichment analysis revealed that mostsignificantly enriched DE circRNAs'host genes were linked to lipid metabolism and adipogenesis processes. The circRNA-miRNAregulatory network analysis found several circRNAs targeting miRNAs associated with adipogenesis. Finally, a novel circRNA,circPPARA, was identified with the expression positively correlated with the IMF content. Detailed analysis revealed that circPPARAwas formed via head-to-tail splicing and was more stable than the linear PPARA, predominantly located in the cytoplasm. Functionalstudies using overexpression and siRNA constructs demonstrated that circPPARA promotes differentiation and hinders theproliferation of porcine intramuscular preadipocytes. Moreover, the dual-luciferase assay revealed that circPPARA adsorbed miR-429and miR-200b, thereby promoting intramuscular adipogenesis in pigs. Our results identified a candidate circRNA, circPPARA, thataffects porcine IMF content. The study provides knowledge of the regulatory functions of circRNAs in intramuscular adipogenesisand abundant resource for future research on circRNAs in pigs.