Melanocortin signaling: genetic insight from X-linked color mutations in non-model organisms

 描述（由申请人提供）：小鼠毛色突变的定位克隆为识别和理解在生物学和疾病中发挥基本作用的旁分泌信号通路提供了基础。被称为色素类型转换的现象--毛囊黑素细胞在红/黄褐黑素与黑/棕真黑素的产生之间转换--对于神经内分泌、肾上腺、外分泌和色素系统所使用的途径特别有用，因为黑皮质素1受体发挥了中心作用。化学诱变和反向遗传学的大规模努力正在逐渐饱和实验室小鼠作为基因发现工具的潜力，但基因组技术的进步已经将正向遗传学的范围扩展到传统的模式生物之外。虽然这些途径在进化上是保守的，但颜色变化作为表型读数的敏感性，加上观察和选择伴侣动物和家畜中不寻常突变的机会，提供了额外的机会。目前的建议集中在两个“经典”毛色突变的非模式生物，橙子在家猫和性连锁黄色（Sly）在叙利亚仓鼠;这些是特别有趣的，因为它们是X连锁的，但模仿常染色体黑皮质素1受体（Mc 1 r）的功能丧失突变。我们的初步研究已经确定了橙子的候选突变和机制，以及Sly的遗传图谱位置和定位克隆策略。关于黑皮质素信号传导的遗传学和生物学的其他知识将来自：（1）培养细胞和转基因动物中的实验遗传学研究，以实验方式确认和探索橙子的分子病理生理学;和（2）仓鼠Sly突变的分子鉴定和表征。

 DESCRIPTION (provided by applicant): Positional cloning of mouse coat color mutations has provided a foundation for identifying and understanding paracrine signaling pathways that play fundamental roles in biology and disease. The phenomenon known as pigment-type switching-whereby hair follicle melanocytes switch between the production of red/yellow pheomelanin vs. black/brown eumelanin-has been especially informative for pathways used by the neuroendocrine, adrenal, exocrine, and pigmentary systems because of the central role played by the Melanocortin 1 receptor. Large-scale efforts in chemical mutagenesis and reverse genetics are gradually saturating the potential of the laboratory mouse as a tool for gene discovery, but advances in genomic technology have extended the reach of forward genetics beyond traditional model organisms. Although the pathways are evolutionarily conserved, the sensitivity of color variation as a phenotypic readout coupled with the opportunity to observe and select for unusual mutations in companion and domestic animals provides additional opportunities. The current proposal focuses on two "classical" coat color mutations in non-model organisms, Orange in the domestic cat and Sex-linked yellow (Sly) in the Syrian hamster; these are especially interesting because they are X-linked, yet mimic a loss-of-function mutation in the autosomal Melanocortin 1 Receptor (Mc1r). Our preliminary studies have identified a candidate mutation and mechanism for Orange, and a genetic map position and positional cloning strategy for Sly. Additional knowledge about the genetics and biology of melanocortin signaling will come from: (1) Experimental genetic studies in cultured cells and in transgenic animals to experimentally confirm and explore the molecular pathophysiology of Orange; and (2) Molecular identification and characterization of the hamster Sly mutation.