A possible involvement of melanocortin 1-receptor in regulating feather color pigmentation in the chicken

摘要

The Extended black (E) locus on chromosome 1 acts within the melanocyte to regulate feather color pigmentation in the chicken. Several alleles exhibiting different pigmentation have been described and their phenotypes are similar to those of the murine extension locus which encodes melanocortin 1-receptor (MCl-R), the receptor for a-melanocyte-stimulating hormone (a-MSH). To investigate whether the MCl-R gene is responsible for E-locus function, we examined the structure of MCl-R in E-locus mutants by RFLP analysis and genomic DNA sequencing. In the most recessive allele (ey), which exhibits a uniformly red-yellow pigmentation, MCl-R was found to contain amino acid substitutions possibly causing functional deficiency. On the other hand, in the most dominant allele (E), which confers a uniformly black pigmentation, MCl-R possessed mutation responsible for a constitutive^ active MCl-R and resultant black coat color in mice. Our finding that the structure of MCl-R was affected by individual E-locus alleles strongly suggests that MCl-R is associated with the E-locus. Furthermore, since the same mutation of MCl-R was found in mice and chickens that exhibit the same pigmentation, it is possible that the regulatory mechanism of MCl-R function is shared in chickens and mammals.