Transcriptomic Analysis of Muscle Satellite Cell Regulation on Intramuscular Preadipocyte Differentiation in Tan Sheep

Intramuscular fat (IMF) content is a key factor influencing meat properties including tenderness, flavor, and marbling. However, the complex molecular mechanisms regulating IMF deposition, especially the interactions between intramuscular preadipocytes (IMAdCs) and skeletal muscle satellite cells (SMSCs), remain unclear. In this study, a direct co-culture system of sheep IMAdCs and SMSCs was used to elucidate their intercellular interactions. RNA sequencing and bioinformatics analyses were performed under monoculture and co-culture conditions for later stages of differentiation. The obtained results showed that SMSCs significantly inhibited the adipogenic capacity of IMAdCs. This was reflected in the co-culture markedly altered gene expression and observations of lipid droplets in our studies, i.e., the <i>PPARG</i>, <i>ACOX2</i>, <i>PIK3R1</i>, <i>FABP5</i>, <i>FYN</i>, <i>ALDOC</i>, <i>PFKM</i>, <i>PFKL</i>, <i>HADH</i>, and <i>HADHB</i> genes were down-regulated in the co-cultured IMAdCs in association with the inhibition of fat deposition, whereas <i>ACSL3</i>, <i>ACSL4</i>, <i>ATF3</i>, <i>EGR1,</i> and <i>IGF1R</i> within the genes upregulated in co-culture IMAdCs were associated with the promotion of lipid metabolism. In addition, GO, KEGG, and ligand-receptor pairing analyses further elucidated the molecular mechanisms of intercellular communication. These findings emphasize the regulatory role of SMSCs on intramuscular preadipocyte differentiation and lipid metabolism, providing a theoretical framework for targeted molecular strategies to improve sheep meat quality.