The Mechanisms of Fur Development and Color Formation in American Mink Revealed Using Comparative Transcriptomics

SIMPLE SUMMARY: The American mink is a fur animal that has been successfully domesticated by humans. The fur products made of mink are fine, soft and strong, plush and glossy, which are deeply loved by people. The original color of farmed mink is dark brown, but people are not satisfied with a single color of fur products. After more than one hundred years of breeding, a variety of colorful fur colors have been produced. Because white is easy to dye and black can be paired with anything, these two mink species are the most widely farmed. However, the molecular mechanisms of the color formation and fur development of these two minks remain unclear. Through skin transcriptome analysis of these two minks, we obtained the molecular mechanism of their coat color formation and fur development. The expression of tyrosinase and tyrosinase-related protein genes is the main reason for the formation of coat color. The keratin associated protein gene is the main regulatory gene for fur development. The research in this paper can provide data support for good breeding of mink. ABSTRACT: American mink fur is an important economic product, but the molecular mechanisms underlying its color formation and fur development remain unclear. We used RNA-seq to analyze the skin transcriptomes of young and adult mink with two different hair colors. The mink comprised black adults (AB), white adults (AW), black juveniles (TB), and white juveniles (TW) (three each). Through pair comparison and cross-screening among different subgroups, we found that 13 KRTAP genes and five signaling pathways (the JAK–STAT signaling pathway (cfa04630), signaling pathways regulating pluripotency of stem cells (cfa04550), ECM–receptor interaction (cfa04512), focal adhesion (cfa04510), and the Ras signaling pathway (cfa04014)) were related to mink fur development. We also found that members of a tyrosinase family (TYR, TYRP1, and TYRP2) are involved in mink hair color formation. The expression levels of TYR were higher in young black mink than in young white mink, but this phenomenon was not observed in adult mink. Our study found significant differences in adult and juvenile mink skin transcriptomes, which may shed light on the mechanisms of mink fur development. At the same time, the skin transcriptomes of black and white mink also showed differences, with the results varying by age, suggesting that the genes regulating hair color are active in early development rather than in adulthood. The results of this study provide molecular support in breeding for mink coat color and improving fur quality.