Mapping adiposity genes in mice

描述（由申请人提供）：在小鼠中，许多基因组区域包含导致肥胖差异的变异（Reed 2003; 2006; 2007; 2008）。本研究项目的目标是在小鼠9号染色体上找到与数量性状位点Adip5相关的一个或多个基因，Adip5与性腺脂肪库的体重增加有关。尽管一些证据表明，基因或遗传变异有能力调节肥胖，但导致这种影响的确切基因或DNA序列尚不清楚。QTL Adip5具有使其成为定位克隆方法的实际目标的特征：它对母体效应或上位性相互作用不特别敏感，并且与独特的表型（性腺储备重量）相关。此外，实验计划的目的是在基因座被印迹（即存在亲本效应）的情况下鉴定Adip5。在目前的Adip5置信区间内，有几个可信的候选基因（Bbs4、cyp19a1、Crabp1、Cplx3、Il18、Lipc、Nedd4），以及几十个功能未知的基因和非编码RNA。使用我们实验室为此目的开发的9号染色体替代菌株（CSS-9），我们将这些小鼠与宿主菌株（C57BL/6ByJ; B6）回交，并进行基因组扫描以减小Adip5 （CSS-9 X B6 N2基因组扫描；目的1）的置信区间。基于遗传定位信息提供的精细置信区间，我们将通过连续的育种周期将该染色体解析为小区间，并创建微同源菌株（< 200kb），其中一个将包含Adip5 （Aim 2）的基因。为了确定Adip5的确切基因，我们将对一个或多个小鼠品系进行基因工程，通过同源重组将129 DNA片段替换为B6背景，并评估其对性腺储备体重的影响（Specific Aim 3）。这项工作的长期目标是开发一种方法来系统地识别导致小鼠肥胖正常变异的基因。公共卫生相关性：和人一样，在标准条件下，给老鼠喂食标准饮食时，它们的自然脂肪会有所不同。通过杂交老鼠，我们可以检查肥胖老鼠之间共有的基因和等位基因的模式，以及它们与瘦老鼠之间没有的模式。通过在一个特定区域（小鼠9号染色体）发现有影响的DNA变异，我们希望了解这种变异是如何导致人类肥胖的。

DESCRIPTION (provided by applicant): In mice, many genomic regions contain variation that results in differences in adiposity (Reed 2003; 2006; 2007; 2008). The goal of this research program is to find the gene or genes on mouse chromosome 9 that account for the quantitative trait locus Adip5, which is associated with increased weight of the gonadal adipose depot. Although several lines of evidence suggest that a gene or genetic variant here has the ability to regulate adiposity, the exact gene or DNA sequence that causes this effect is not known. The QTL Adip5 has features that make it a practical target for a positional cloning approach: it is not particularly susceptible to maternal effects or epistatic interactions, and it is associated with a distinct phenotype (gonadal depot weight). Furthermore, the experimental plan is designed to identify Adip5 if the locus is imprinted (i.e., if there are parent-of-origin effects). Within the current Adip5 confidence interval, there are several credible candidate genes (Bbs4, Cpy19a1, Crabp1, Cplx3, Il18, Lipc, Nedd4), as well as dozens of genes and noncoding RNA of unknown function. Using a chromosome 9 substitution strain developed in our laboratory for this purpose (CSS-9), we will backcross these mice to the host strain (C57BL/6ByJ; B6) and conduct a genome scan to reduce the confidence interval of Adip5 (CSS-9 X B6 N2 genome scan; Aim 1). Based on the refined confidence interval provided by the genetic mapping information, we will parse this chromosome into small intervals through successive breeding cycles, and create microcongenic strains (<200 kb), one of which will contain the gene responsible for Adip5 (Aim 2). To identify the exact gene responsible for Adip5, we will genetically engineer one or more mouse strains with a segment of 129 DNA substituted into a B6 background by homologous recombination, and evaluate its effect on gonadal depot weight (Specific Aim 3). The long-range goal of this work is to develop an approach to systematically identify genes that contribute to normal variation in fatness among mice. PUBLIC HEALTH RELEVANCE: Like people, mice vary in how naturally fat they are when fed a standard diet, under standard conditions. By interbreeding mice, we can examine the pattern of genes and alleles that fat mice share with each other and which they do not share with lean mice. By finding influential DNA variation in one specific region (on mouse chromosome 9), we hope to learn how this variation contributes to obesity in humans.