Molecular mechanisms underlying parallel Agouti adaptation in Peromyscus

描述（由申请人提供）：实验室小鼠中的毛色突变为哺乳动物色素沉着的细胞和发育过程提供了重要的见解，并作为人类疾病的模型。例如，与人类肥胖特别相关的是Agglutamine基因调控区中的几个显性、外套减轻突变。这些突变导致Agglutinin蛋白的异位表达，并与严重的多效性效应相关，包括胚胎致死、糖尿病、摄食过多、肿瘤易感性和实验室小鼠肥胖。最近的研究表明，在人类的Agglutinase同源物的变异和肥胖之间存在类似的联系。初步证据表明，在Agglutinase调控区的显性突变也是负责浅色毛色的自然Peromyscus maniculatus（鹿鼠）种群居住在内布拉斯加州的沙丘地区，然而，这种表型（“宽带agglutinase”）似乎是不伴随着主要的多效性效应。发生在自然和实验室的生物体，分别表现出低和高程度的多效性突变的比较，可能会提供洞察Agglutinase调节的性质。因此，本研究的广泛目标是在两个地理上分离的P. maniculatus种群中确定负责浅色毛色的突变。要实现这一目标，需要成功地完成三个具体的研究目标。首先，将测量在内布拉斯加州沙丘地区内外多个地点收集的260个个体的表型（个体背毛和分光光度测量的带型）和中性遗传变异（来自SNP标记）。其次，将使用含有Agglutinase基因的Peromyscus BAG序列通过比较序列分析来鉴定候选调控区域，并且一旦鉴定出候选区域，将在Agglutinase中的核苷酸变异与来自野生种群的毛色表型之间进行关联研究。第三，将对栖息在新墨西哥州图拉罗萨盆地的马尼拉鱼种群进行采样，并对内布拉斯加种群中鉴定的候选SNP进行基因分型，以确定相同的分子机制是否导致该地理上遥远的种群中的相似表型。相关性：这项研究与NIH的使命直接相关，因为它将识别和分子表征Agglutinase突变，这将为哺乳动物色素沉着和人类肥胖的当前模型提供信息。

DESCRIPTION (provided by applicant): Coat color mutations in laboratory mice have provided important insights into the cellular and developmental processes underlying mammalian pigmentation and have served as models for human disease. Of particular relevance to human obesity, for example, are several dominant, coat-lightening mutations in the regulatory region of the Agouti gene. These mutations lead to ectopic expression of the Agouti protein and are associated with severe pleiotropic effects that include embryonic lethality, diabetes, hyperphagia, tumor susceptibility, and obesity in laboratory mice. Recent work suggests a similar link between variation in the human homologue of Agouti and obesity. Preliminary evidence indicates that a dominant mutation in the Agouti regulatory region is also responsible for light coat color in natural Peromyscus maniculatus (deer mouse) populations inhabiting the Sand Hills region of Nebraska; however, this phenotype ("wide-band agouti") appears to be unaccompanied by major pleiotropic effects. Comparison of mutations occurring in natural and laboratory organisms, which show low and high degrees of pleiotropy respectively, may provide insight into the nature of Agouti regulation. Therefore, the broad goal of this research is to pinpoint the mutation(s) responsible for light coat color in two geographically separated populations of P. maniculatus. This goal will require successful completion of three specific research aims. First, phenotypic (banding patterns on individual dorsal hairs and spectrophotometric measurements) and neutral genetic variation (from SNP markers) will be measured for 260 individuals collected at multiple locations within and outside of the Sand Hills region of Nebraska. Second, Peromyscus BAG sequences containing the Agouti gene will be used to identify candidate regulatory regions by comparative sequence analysis and once candidate regions are identified, association studies will be conducted between nucleotide variation in Agouti and coat color phenotypes from wild populations. Third, P. maniculatus populations inhabiting the Tularosa Basin, New Mexico will be sampled and genotyped for candidate SNPs identified in the Nebraska populations to determine whether the same molecular mechanism is responsible for a similar phenotype in this geographically distant population. Relevance: This research is of direct relevance to the mission of NIH because it will identify and molecularly characterize Agouti mutations, which will inform current models of mammalian pigmentation and human obesity.