Identification of Candidate miRNAs Associated with Shear Force and Intramuscular Fat in Pig Breeds

In this comparative study of 12 pigs (six Songlei black [SL] and six Duroc × Landrace × Yorkshire [DLY]), small RNA sequencing was performed on longissimus dorsi muscle samples to identify miRNAs associated with meat quality traits. A total of 343 known and 191 novel miRNAs were identified, including 21 differentially expressed miRNAs (DE-miRNAs) between breeds. Enrichment analysis showed that their target genes were enriched in the PI3K-Akt, MAPK, and calcium signaling pathways. Integration of miRNA and transcriptome datasets identified a regulatory network comprising five key miRNAs (ssc-miR-10383, ssc-miR-127, ssc-miR-370, ssc-miR-874, and a novel miRNA, novel_494) and 32 target genes annotated to autophagy, AMPK, mTOR, and FoxO signaling pathways. All five miRNAs were negatively correlated with IMF content (r = -0.77 to -0.95) and positively correlated with shear force (r = 0.62 to 0.76). This study provides the first miRNA expression profile of the longissimus dorsi muscle in SL and DLY pigs. These findings suggest that coordinated miRNA regulation may contribute to breed-specific differences in fat deposition and meat tenderness, providing candidate biomarkers for improving pork quality.