SCD-Mediated Oleic Acid-PPARγ Self-Reinforcing Loop Drives Porcine Intramuscular Fat Deposition

Intramuscular fat (IMF) deposition is a key determinant of pork quality and canonically regulated by peroxisome proliferator-activated receptor gamma (PPARγ). However, PPARγ expression levels do not always correlate directly with fat deposition, suggesting that transcript abundance alone is insufficient to account for the adipogenic potential. Here, we identified a self-reinforcing stearoyl-CoA desaturase (SCD)-oleic acid (OA)-PPARγ feedback loop that amplifies lipid metabolic gene expression and drives efficient IMF accumulation. Multilayer omics integration and functional assays showed that SCD-derived OA acts as an endogenous ligand to activate PPARγ, while PPARγ transcriptionally upregulates SCD, together amplifying a broad lipid metabolic gene network. Both SCD overexpression and OA-delivery nanoparticles consistently promoted IMF deposition in vivo, supporting the central role of this SCD-OA-PPARγ axis. Our findings reveal a conserved but dynamic feedback mechanism underlying IMF deposition and provide a molecular explanation for breed-specific differences in pork quality.