Characterization of Growth of Secondary Hair in Min Pig Activated by Follicle Stem Cell Stimulated by Wnt and BMP Signaling Pathway

In China, the national-level protected pig, Min pig, is characterized by the development of secondary hairs and hair follicles in winter. Factors that dominate the genotype in the growth of secondary hairs are not clear through the concrete cell signaling pathways. This study compared hair phenotypes based on morphological structure, transcriptomics, and potential targeting molecules in the breeds of Min, Berkshire, and Yorkshire pigs. The results indicated that the Min pigs have specific characteristics for the growth of secondary hairs, which are different from those in the Berkshire and Yorkshire pigs. The transcriptome analyses and quantitative reverse transcription-polymerase chain reaction results revealed that secondary hair growth was activated by follicle stem cell. The specific signaling molecules Wnt and BMP were studied using respective inhibitors. The density of follicles, activity of follicle stem cells, and relative gene expression results have shown that Wnt and BMP stimulate the activity of follicle stem cells, and the Wnt signaling molecule has a significantly better effect than the BMP signaling molecule on stem cells. Wnt and BMP can inhibit the growth of local secondary hair and gene expression. Therefore, this study was conducted to verify the relationship between the signaling pathway of stem cells and the development of secondary hair in Min pigs, which contributes to the thermoregulatory mechanisms of hair regeneration and hair loss.