Intramuscular fat (IMF) is an important economic trait for pork quality and a complex quantitative trait regulated by multiple genes. The objective of this work was to investigate the novel transcriptional effects of a multigene pathway on IMF deposition in the longissimus dorsi (LD) muscles of pigs. Potential signaling pathways were screened by mining data from three gene expression profiles in the Gene Expression Omnibus (GEO) database. We designed quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) arrays for the candidate signaling pathways to verify the results in the LD muscles of two pig breeds with different IMF contents (Large White and Min). Western blot analysis was used to detect the expression levels of several candidate proteins. Our results showed that the AMPK signaling pathway was screened via bioinformatics analysis. Ten key hub genes of this signaling pathway (AMPK, ADIPOR1, ADIPOR2, LKB1, CAMKKβ, CPT1A, CPT1B, PGC-1α, CD36, and ACC1) were differentially expressed between the Large White and Min pigs. Western blot analysis further confirmed that LKB1/CaMKK2-AMPK-ACC1-CPT1A axis dominates the activity of AMPK signaling pathway. Statistical analyses revealed that AMPK signaling pathway activity clearly varied among the two pig breeds. Based on these results, we concluded that the activation of the AMPK signaling pathway plays a positive role in reducing IMF deposition in pigs.

Porcine reproductive and respiratory syndrome (PRRS), caused by PRRSV, causes substantial economic losses in the swine industry. Because viral variability and host genetic complexity limit conventional control, identifying host genetic factors associated with PRRS resistance through genomic approaches is important for disease-resistant breeding. In this study, 699 pigs were immunized with a PRRSV vaccine, 135 were selected for PRRSV infection experiments, and 133 were retained for whole-genome resequencing after two-stage phenotypic screening based on post-immunization and post-infection profiles. Genome-wide selection-signal analysis identified 12 highly differentiated regions (F_st > 0.15), annotated to 11 candidate genes: NFXL1, NIPAL1, CHIC2, LOC100623351, LOC100513671, LOC100513484, CENPC, STAP1, UBA6, GNRHR, and LOC100512727. The original exploratory GWAS identified candidate association signals, including signals annotated to PYGM, NFXL1, KIAA1324L, and FLNC; after PC1/PC2 adjustment, NFXL1 retained exploratory support, and additional exploratory signals were observed. Public PRRSV-related transcriptomic datasets provided additional expression-level evidence, with NIPAL1 and PYGM showing increased expression in PRRSV-infected porcine alveolar macrophages. Functional enrichment and variant-level analyses supported the biological relevance of the prioritized candidate gene set, particularly the chromosome 8 NFXL1 region, where the A-C-G haplotype was more frequent in resistant pigs. These findings provide useful genetic clues for further validation and PRRS resistance breeding.