Mapping adiposity genes in mice

描述（由申请人提供）：在小鼠中，许多基因组区域含有导致肥胖差异的变异（Reed 2003; 2006; 2007; 2008）。这项研究计划的目标是找到小鼠9号染色体上的一个或多个基因，这些基因负责数量性状基因座Adip 5，该基因座与性腺脂肪库的重量增加有关。虽然有几条证据表明，这里的基因或遗传变异具有调节肥胖的能力，但导致这种影响的确切基因或DNA序列尚不清楚。QTL Adip 5具有使其成为位置克隆方法的实用靶标的特征：它对母体效应或上位性相互作用不是特别敏感，并且它与独特的表型（性腺贮库重量）相关。此外，实验计划被设计为如果基因座被印迹（即，如果存在原始效果的父项）。在当前Adip 5置信区间内，存在几个可信的候选基因（Bbs 4、Cpy 19 a1、Crapp 1、Cplx 3、Il 18、Lipc、Nedd 4），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号染色体置换品系（CSS-9），我们将这些小鼠与宿主品系（C57 BL/6 ByJ; B6）回交，并进行基因组扫描以降低Adip 5的置信区间（CSS-9 X B6 N2基因组扫描; Aim 1）。基于遗传图谱信息提供的精确置信区间，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（<200 kb），其中一个将包含负责Adip 5（Aim 2）的基因。为了鉴定负责Adip 5的确切基因，我们将通过同源重组将一段129 DNA替换到B6背景中，对一个或多个小鼠品系进行遗传工程改造，并评估其对性腺贮库重量的影响（具体目标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化的基因。公共卫生相关性：像人一样，在标准条件下，当喂食标准饮食时，小鼠的自然脂肪量不同。通过杂交小鼠，我们可以检查胖小鼠彼此共享的基因和等位基因的模式，以及它们与瘦小鼠不共享的模式。通过在一个特定区域（小鼠9号染色体上）发现有影响力的DNA变异，我们希望了解这种变异如何导致人类肥胖。

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.