Imsland Freyja, McGowan Kelly, Rubin Carl-Johan, Henegar Corneliu, Sundström Elisabeth, Berglund Jonas, Schwochow Doreen, Gustafson Ulla, Imsland Páll, Lindblad-Toh Kerstin, Lindgren Gabriella, Mikko Sofia, Millon Lee, Wade Claire, Schubert Mikkel, Orlando Ludovic, Penedo Maria Cecilia T, Barsh Gregory S, Andersson Leif
Science for Life Laboratory Uppsala, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, USA.
Nat Genet. 2016 Feb;48(2):152-8. doi: 10.1038/ng.3475. Epub 2015 Dec 21.
Dun is a wild-type coat color in horses characterized by pigment dilution with a striking pattern of dark areas termed primitive markings. Here we show that pigment dilution in Dun horses is due to radially asymmetric deposition of pigment in the growing hair caused by localized expression of the T-box 3 (TBX3) transcription factor in hair follicles, which in turn determines the distribution of hair follicle melanocytes. Most domestic horses are non-dun, a more intensely pigmented phenotype caused by regulatory mutations impairing TBX3 expression in the hair follicle, resulting in a more circumferential distribution of melanocytes and pigment granules in individual hairs. We identified two different alleles (non-dun1 and non-dun2) causing non-dun color. non-dun2 is a recently derived allele, whereas the Dun and non-dun1 alleles are found in ancient horse DNA, demonstrating that this polymorphism predates horse domestication. These findings uncover a new developmental role for T-box genes and new aspects of hair follicle biology and pigmentation.
骝色是马的一种野生型毛色，其特征是色素稀释，并带有显著的深色区域图案，称为原始斑纹。我们在此表明，骝色马的色素稀释是由于毛囊中T盒3（TBX3）转录因子的局部表达导致生长毛发中色素的径向不对称沉积，这反过来又决定了毛囊黑素细胞的分布。大多数家养马是非骝色的，这是一种色素沉着更深的表型，由调节性突变导致毛囊中TBX3表达受损引起，导致单个毛发中黑素细胞和色素颗粒的分布更呈圆周状。我们鉴定出了两种导致非骝色的不同等位基因（非骝色1和非骝色2）。非骝色2是最近衍生出的等位基因，而骝色和非骝色1等位基因则存在于古代马的DNA中，这表明这种多态性早于马的驯化。这些发现揭示了T盒基因的一个新的发育作用以及毛囊生物学和色素沉着的新方面。
