Comparative transcriptome analysis of slow-twitch and fast-twitch muscles in Kazakh horses

This study conducted a thorough analysis of the myofiber type composition in the extensor digitorum longus muscle (EDL) and soleus muscle (SOL) of Kazakh horses, across different genders (male and female). The results showed significant differences in myofiber type composition between EDL and SOL, with a higher proportion of Type I fibers in SOL muscles and a greater prevalence of Type II fibers in EDL muscles. Additionally, the myofiber diameter in Kazakh horses was relatively small, potentially related to the tenderness and edible quality of their muscles. Using high-throughput sequencing technology, we constructed 32 cDNA sequencing libraries and obtained high-quality read data. Gene expression analysis revealed 278 and 372 differentially expressed genes (DEGs) in EDL and SOL muscles, respectively, including genes related to muscle contraction, metabolism, and development. Intersection analysis of DEGs between genders showed that 60 DEGs were significantly different in both male and female horses. GO annotation and KEGG analysis further elucidated the roles of these DEGs in muscle structure, function, and cellular signaling. Protein-protein interaction (PPI) network analysis and identification of hub genes provided new insights into the molecular mechanisms underlying muscle growth and development. Finally, the reliability of the DEGs data was validated through quantitative real-time PCR (qRT-PCR). This study not only enhances our understanding of the biological characteristics of horse muscles but also provides potential molecular targets for improving horse muscle performance and health.