Single-cell Sequencing Reveals That Transcriptome Map And Molecular Features Of Primary And Secondary Hair Follicles In Liaoning Cashmere Goats

The hair follicle is a dynamic miniature organ that is "assembled" over time from a variety of epithelial and mesenchymal cells,with complex cellular heterogeneity in its internal structure.In the process of periodic hair regeneration,the hair follicle repeatedly undergoes the remodeling process of various tissues,which has always been an important issue.In order to analyze the tissue structure and development process of hair follicles at the cellular level,this study uses single-cell sequencing technology to reveal the cell map of the hair follicle of Liaoning cashmere goat,which contains 6596 primary hair follicle cells and 4271 secondary hair follicle cells.A total of 15 cell populations.We analyzed these cell clusters in terms of molecular characteristics,cell developmental trajectories,and species conservation and specificity.The main contents of this research are as follows:(1)The single-cell transcriptome map of primary and secondary hair follicles of Liaoning cashmere goat is established for the first time.On the basis of separating the primary and secondary hair follicles of cashmere goats,we divide the hair follicles into top,middle and bottom segments for single-cell transcriptome sequencing,and identified 15 major cell clusters.Including the differentiation and development process,the transitional cell population – hair germ.For the first time,the cell populations of the primary and secondary hair follicles of cashmere goats were compared and analyzed,and the differential cell populations and characteristic molecules in the primary and secondary hair follicles are found,and the genes related to the medulla and hair fineness were revealed significant differential expression among primary hair follicle cell populations and secondary follicle cell populations.The high-quality single-cell transcriptome map we established provides an accurate reference for the study of the structure,morphology,growth and development of primary and secondary hair follicles in cashmere goats.(2)Based on the mining of the transcriptome map of hair follicle stem cells,we reshaped the global transcriptome dynamics of the transition process of hair follicle stem cells from the primitive state to the end of differentiation,and discovered the characteristic molecules of hair follicle stem cells at different developmental stages.Differentially expressed characteristic genes and functional analysis found that secondary hair follicle stem cells highly expressed genes related to the regulation of hair follicle development,and significantly enriched signaling pathways such as TGF-β,Wnt and Notch that regulate hair follicle growth,while in primary hair follicle stem cells,differentially expressed genes.The expressed characteristic genes are mainly involved in maintaining the proliferation and growth of hair follicles.We find that the active hair follicle stem cells in the initial state of differentiation mostly exist in the secondary hair follicles,indicating that the secondary hair follicle stem cells are in a strong growth and differentiation state at this time,while most of the primary hair follicle stem cells are in the terminal state of maintaining growth,revealing the dynamic changes of gene expression during the development of hair follicle stem cells.(3)Species conservation and specificity analysis of cashmere goat,human and mouse hair follicle cells.Through the integrated analysis of the single-cell sequencing data of anagen hair follicles of Liaoning cashmere goat,mouse and human,11 cell clusters are identified,and it is found that the same cell type is highly conserved in different species,and found that the same cell type is highly conserved in different species.36 homologous transcription factors that regulate proliferation and differentiation are differentially expressed in all three species.The key rhythmregulating genes Clock,Arntl and Per1 are highly conserved and highly expressed in the three species,while the expression levels of rhythm genes related to the seasonal and environment are significantly higher in goat hair follicles than in human and mouse.In this study,we first systematically establish high-precision single-cell transcriptome maps of primary and secondary hair follicles in the early anagen stage of cashmere,and carried out in-depth analysis and mining.