Abstract: 【Objective】 The transcriptome sequencing was performed on the skin tissue of the scapular region in Tianzhu White yaks at different age stages,the differentially expressed genes (DEGs) at different age stages were screened,and the function and interaction relationship of DEGs were analyzed,so as to provide a theoretical basis for analyzing the molecular mechanism of skin tissue development process in yak adapting to the alpine environment. 【Method】 The skin tissue of the scapular region in Tianzhu White yaks in good health and growth condition at the ages of 0.5,2.5,and 4.5 years were collected for RNA-Seq.The DEGs were screened with the thresholds of Q＜0.05 and |log₂FoldChange|＞1.Then,GO function and KEGG pathway enrichment analysis were conducted for DEGs.Seven DEGs were randomly selected for Real-time quantitative PCR to verify RNA-Seq results. 【Result】 Among the 605 obtained DEGs,364,153,and 88 DEGs were screened in 2.5 vs 0.5,4.5 vs 0.5,and 4.5 vs 2.5 groups.GO functional enrichment analysis showed that DEGs in 2.5 vs 0.5 group were related to the immune response included positive regulation of immune response,keratinization,neutrophil chemotaxis and chemokine activity,DEGs in 4.5 vs 0.5 group were related to the immune response included positive regulation of chemokine secretion,chemokine activity and response to bacteria,and DEGs in 4.5 vs 2.5 group were related to the immune response included immune response and peptidase inhibitor activity.KEGG pathway annotation results indicated that DEGs in 2.5 vs 0.5 and 4.5 vs 0.5 groups were significantly enriched in immune-related pathways such as the interaction between viral proteins and cytokines and cytokine receptors,IL-17 signaling pathway,and cytokine-cytokine receptor interaction,and DEGs in 4.5 vs 2.5 group were significantly enriched in ABC transporters, Staphylococcus aureus infection,complement and coagulation cascade reaction,etc.Through the enrichment results,30 genes related to skin immune regulation were screened out,and the protein-protein interaction network analysis map was made by STRING database and Cytoscape software,and IL-6,IL-1A,and CCL20 with higher scores were screened as the core proteins.The results of Real-time quantitative PCR were consistent with the expression trend of RNA-Seq,indicating that RNA-Seq results were reliable. 【Conclusion】 The number of DEGs in skin tissues of Tianzhu White yaks at different age stages were revealed in this study,as well as the function and pathway of DEGs.Through analysis,it was believed that pathways such as the IL-17 signaling pathway were associated with the development and regulation of the skin immune function in Tianzhu White yaks,and key regulatory genes such as IL-6,IL-1A and CCL20 were screened.The results provided a reference for comprehensively understanding the regulation mechanism of the skin immune function and related genes in Tianzhu White yaks.

Key words: Tianzhu White yak; skin; transcriptome; immunity