Single-nucleus RNA sequencing and metabolomics reveal evolutionary divergence in muscle fiber programming between horses (Equus caballus) and donkeys (Equus asinus)
image: Fig. 1 Cell composition in the skeletal muscle across species by sc/snRNA-seq analysis
Credit: Cong Li
Skeletal muscle cellular heterogeneity and molecular regulation are fundamental to understanding exercise physiology in Equus species. However, these mechanisms remain incompletely characterized in donkeys (Equus asinus) and horses (Equus caballus).
To that end, a team of researchers from Tarim University and Northwest A&F University, China integrated single-nucleus transcriptomics and metabolomics to compare the longissimus dorsi muscle across developmental stages in both species. The team's findings are published in the Journal of Integrative Agriculture.
"We identified nine and twelve distinct skeletal muscle cell types in donkeys and horses, respectively," explains first author Dr. Cong Li at Tarim University and Northwest A&F University. "Muscle fiber composition exhibited species-specific age-related changes: in adult horses, the proportion of both type I and II fibers increased; in adult donkeys, by contrast, the proportion of type I fibers decreased while that of type II fibers increased. The predominance of type II fibers in horses likely reflects a species-specific adaptation to high-intensity locomotor demands."
Pseudotime analysis delineated muscle fiber trajectories and revealed dynamic gene expression profiles along these paths. "Subpopulation analysis of immune cells revealed the activation of pro-inflammatory signaling pathways (TNF and NOD-like receptor pathways) in adult groups, coupled with diminished anti-inflammatory capacity in dendritic cells, collectively indicating an age-associated pro-inflammatory shift," says Li.
Intercellular communication analysis further indicated age-related dysregulation in key signaling pathways, including BMP (adipogenic differentiation), Notch (immune regulation), and IGF (tissue repair), which may contribute to impaired muscle metabolism and regenerative capacity.
At the same time, cross-species comparison revealed that skeletal muscle transcriptomes of donkeys and horses are highly conserved (Pearson correlation coefficient 0.87), although species-specific marker gene expression, such as SLC29A1 in endothelial cells, was observed. "We conducted metabolomic profiling and identified distinct differences in overall metabolite category composition and revealed significantly divergent gene-metabolite networks between the two species," adds Li. "Taken together, our findings illuminate the cellular dynamics, metabolic remodeling, and evolutionary conservation of skeletal muscle development in Equus species, providing valuable insights into mammalian muscle adaptation and identifying potential targets for enhancing locomotor performance or managing myopathies in equids." shares correspondence Prof. Ruihua Dang.
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Contact the author:
Cong Li, E-mail: lc863749946@163.com;
#Correspondence Ruihua Dang, dangruihua@nwsuaf.edu.cn
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