Mongolian cattle is recognized as one of the key outstanding breeds in north of China, with skeletal muscle traits linked to good meat quality and strong labor capacity, but their cellular and molecular mechanisms remain unclear. In this research, single-Nucleus RNA Sequencing (snRNA-seq) was used to analyze cell populations and gene expression in skeletal muscles (triceps brachii muscles and longissimus dorsi muscles as representatives), and then fibro-adipogenic progenitors (FAPs) was isolated from mice skeletal muscles to transfect HSPA1A to explore the functions. The results showed there were a total of 20 cell types or subtypes in triceps brachii muscles and longissimus dorsi muscles, including muscle fibers, adipocytes, FAPs, and endothelial cells. Cell trajectories revealed that satellite/myocytes cells differentiated into type I/IIX and IIA fiber branches. HSPA1A was expressed higher in longissimus dorsi muscle by interacting with IGFBP3 to promote FAPs adipogenic differentiation and collagen production. All findings supplied the evidence of heterogeneous skeletal muscles, especially the roles of FAPs in fat deposition and collagen fiber synthesis which was promoted by HSPA1A.
Ren et al. (2026) studied this question.