circFAM129B Regulates Adipogenesis and Unsaturated Fatty Acid Synthesis by bta-let-7d in Buffalo Intramuscular Preadipocytes

Intramuscular fat (IMF) and unsaturated fatty acid (UFA) contents are critical factors influencing meat quality in livestock. Circular RNAs (circRNAs) have recently emerged as key regulators in lipid metabolism. However, their roles in IMF deposition and UFA synthesis remain largely unexplored in buffalo. Here, high-throughput sequencing of six adipose depots combined with WGCNA identified a novel circRNA (circFAM129B) that was highly correlated with UFA content in buffaloes. The authenticity of circFAM129B was confirmed by sequencing and RNase R treatment. Overexpression of circFAM129B upregulated the expression of adipogenesis and UFA synthesis genes, enhancing lipid accumulation and UFA content, while inhibiting cell proliferation. Mechanistically, circFAM129B sponges bta-let-7d, alleviating its inhibitory effect on SCD. These findings unveil a novel circRNA-mediated regulatory axis modulating adipogenesis and UFA synthesis, offering potential molecular targets for enhancing meat quality and nutritional value in buffaloes.