Molecular Characterization of the Heterogeneity of Satellite Cell Populations Isolated from an Individual Turkey Pectoralis Major Muscle

Satellite cells (SC) are myogenic stem cells responsible for post-hatch muscle growth and the regeneration of muscle. Satellite cells are not a homogenous population of cells within a muscle and have variable rates of proliferation and differentiation even within a single fiber type muscle like the turkey pectoralis major muscle. In the current study, satellite cell clones isolated from the same turkey pectoralis major muscle were compared. These clones were categorized based on their days to confluence in a 25 cm2 flask: early clones with high proliferation and differentiation rates (fast-growing cells) and late clones with a lower rate (slow-growing cells). To comprehensively understand the molecular variances between the fast and slow growing cells, RNA sequencing was conducted on both fast and slow-growing cells, with subsequent comparisons of their transcriptomes after 72 hours of proliferation. Principal Component Analysis confirmed that the transcriptomic profiles of fast and slow-growing SCs are markedly distinct. Differential gene expression analysis identified over 5300 genes that were significantly differentially expressed between the groups. Gene ontology analysis showed that genes enriched in fast growing cells are responsible for the fundamental aspects of muscle biology, including muscle tissue development and structural maturation. Conversely, genes up-regulated in slow growing cells are involved in cell-cell communication, extracellular matrix interactions, signal ligand activity, and cytokine activity, which are key components for forming an extracellular niche essential for functional SC maintenance. Further examination of specific gene ontology categories such as muscle structure development and extracellular matrix components indicated significant differences in gene expression patterns between fast and slow-growing SCs. The distinct roles of these SC subsets suggest that a delicate balance between them is essential for maintaining the normal physiological functions of satellite cells.