Bovine Muscle Satellite Cell-Derived Exosomes Modulate Preadipocyte Adipogenesis via bta-miR-2904

Intramuscular fat (IMF) significantly impacts meat quality. Exosomes have attracted increasing attention for their regulatory roles in muscle-adipose tissue crosstalk; however, their precise mechanisms remain largely unclear. Based on this, this study aimed to establish a muscle-adipose co-culture system to better simulate the in vivo physiological environment. Using exosomal miRNAs as molecular links, we investigated how bovine muscle satellite cells influence lipid accumulation and adipogenesis in preadipocytes. We established a co-culture system of bovine muscle satellite cells and preadipocytes and found that co-culture significantly inhibited lipid droplet accumulation and adipogenesis in preadipocytes. Therefore, we hypothesized that exosomes derived from bovine muscle satellite cells regulate the adipogenic differentiation of bovine preadipocytes through intercellular communication and that specific exosomal miRNAs play pivotal roles in this regulatory process. We successfully isolated and identified muscle-derived (Mu-EXO), adipose-derived (Ad-EXO), and co-culture exosomes (Co-EXO). High-throughput sequencing revealed the differential expression profiles of miRNAs. Notably, the bovine-specific miRNA bta-miR-2904, annotated in miRBase v22 with limited cross-species conservation, was significantly enriched in Mu-EXO and Co-EXO compared with Ad-EXO. Further functional experiments demonstrated that overexpression of bta-miR-2904 markedly inhibited lipid droplet accumulation, triglyceride content, and the expression of adipogenesis-related genes in preadipocytes; inhibition had opposite effects. Our results demonstrate that bovine muscle-derived exosomal miR-2904 inhibits lipid accumulation and adipogenesis in preadipocytes. These results establish a theoretical basis for understanding skeletal muscle-adipose crosstalk and offer a novel molecular target for regulating intramuscular fat deposition in beef cattle.