209 A Single-Cell Atlas of Bovine Skeletal Muscle Tissue Reveals Mechanisms Underlying Differences in Quality between Wagyu and Brahman Beef

Abstract

Abstract Wagyu cattle are renowned for their premium beef characterized by abundant intramuscular fat (IMF). In contrast, Brahman, a popular breed in the southern coastal area of the US, generally produces tough meat with scarce IMF. However, the mechanisms underlying the differential meat quality between the 2 breeds are still largely unknown. Here, using single-cell RNAseq (scRNAseq), we report a single-cell atlas of bovine skeletal muscle tissue. Multiple fibro/adipogenic progenitor (FAP) subpopulations were identified, including an endomysial adipogenic subpopulation and a perimysial fibrogenic subpopulation. Further analysis comparing individual FAP subpopulations between Wagyu and Brahman identified stronger expression of pro-adipogenic genes in Wagyu adipogenic FAP subpopulation and higher expression of pro-fibrogenic genes in Brahman fibrogenic FAP subpopulation. Overexpression of CFD, a gene upregulated in Wagyu adipogenic FAPs, enhanced the adipogenic efficiency of FAPs. Moreover, the expression of CFD in FAPs was positively correlated with the IMF content. Interestingly, the expression of CFD was not identified in FAPs of mouse models of intramuscular adipogenesis, suggesting that CFD is a cattle-specific regulator of IMF formation. Cell-cell communication analysis reveals significant differences between CFD+ FAPs and CFD- FAPs in their interactions with other cell types, further suggesting an important role of CFD+ FAPs in bovine skeletal muscle growth and development.