Data from: Epistatic interaction of the melanocortin 1 receptor and agouti signaling protein genes modulates wool color in the Brazilian Creole sheep

Different pigmentation genes have been associated with color diversity in domestic animal species. The melanocortin 1 receptor (MC1R), agouti signaling protein (ASIP), tyrosinase related protein-1 (TYRP1) and v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) genes are candidate genes responsible for variation in wool color among breeds of sheep. Although the influence of these genes has been described in some breeds, in many others the effect of interactions among genes underlying wool color has not been investigated. The Brazilian Creole sheep is a local breed with a wide variety of wool color, ranging from black to white with several intermediate hues. We analyzed in this study the influence of the genes MC1R, ASIP, TYRP1 and KIT on the control of wool color in this breed. A total of 410 samples were analyzed, including 148 white and 262 colored individuals. The MC1R and ASIP polymorphisms were significantly associated with the segregation of either white or colored wool. The dominant MC1R allele (ED p.M73K and p.D121N) was present only in colored animals. All white individuals were homozygous for the MC1R recessive allele (E+) and carriers of the duplicated copy of ASIP. A gene expression essay showed that only the carrier of the duplicated copy of ASIP produces increased levels in skin, not detectable in the single homozygous copy. These results demonstrate that the epistatic interaction of the genotypes in the MC1R and ASIP gene is responsible for the striking color variation in the Creole breed.

不同色素沉着基因已被证实与家畜物种的毛色多样性相关。黑皮质素1受体（melanocortin 1 receptor, MC1R）、刺鼠信号蛋白（agouti signaling protein, ASIP）、酪氨酸酶相关蛋白1（tyrosinase related protein-1, TYRP1）以及v-kit Hardy-Zuckerman 4猫肉瘤病毒癌基因同源物（v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog, KIT）基因，均为绵羊品种间羊毛颜色变异的候选功能基因。尽管已有研究在部分绵羊品种中阐明了上述基因对毛色的调控作用，但在多数品种中，羊毛颜色相关基因间的互作效应仍未得到深入探究。巴西克里奥尔绵羊是一种地方品种，其羊毛颜色丰富多样，覆盖从黑色到白色的一系列过渡色阶。本研究针对上述MC1R、ASIP、TYRP1及KIT基因在该品种羊毛颜色调控中的作用展开分析。本研究共分析410份样本，其中148份来自白色毛羊个体，262份来自有色毛羊个体。MC1R与ASIP基因的多态性与羊毛颜色（白色或有色）的分离存在显著关联。显性MC1R等位基因（ED，包含p.M73K和p.D121N两个位点突变）仅存在于有色毛羊个体中。所有白色毛羊个体均为MC1R隐性等位基因（E+）的纯合子，且携带ASIP基因的重复拷贝。基因表达实验结果显示，仅携带ASIP基因重复拷贝的个体，其皮肤组织中该基因的表达水平显著升高；而仅携带单份纯合ASIP拷贝的个体则无法检测到该高表达现象。本研究结果证实，MC1R与ASIP基因的基因型上位互作，是导致巴西克里奥尔绵羊出现显著毛色变异的关键原因。