Nicotine consumption QTL: Fine mapping, selective breeding and sequencing

 描述(申请人提供)：遗传学显然有助于人类尼古丁依赖的个体风险和实验动物尼古丁敏感性的变化。在小鼠身上，一些对尼古丁的行为和生理反应已经被证明受到遗传因素的影响。然而，没有一种特定的基因对小鼠的尼古丁敏感性产生遗传影响。这些基因仍然是一个尚未开发的信息来源，几乎可以肯定，这些信息将提高我们对尼古丁敏感性个体差异的理解。例如，最近发现人类CHRNA5的变异与人类尼古丁依赖的风险有关，这导致了对啮齿动物的后续研究，这些研究不仅有助于确定对控制尼古丁摄入量至关重要的特定神经通路，而且还表明，该基因影响尼古丁自我给药的个体差异，不是通过增加对低剂量尼古丁增强效应的敏感性，而是缺乏在厌恶剂量时增强增强的丧失。这只是许多例子中的一个，这些例子表明，识别导致表型测量中个体变异性的基因可以导致对潜在的 测量的生物学。我们之前已经绘制了染色体区域，这些区域包含一个或多个基因，这些基因导致小鼠口服尼古丁摄入量的个体差异，本项目的目标是跟进这一初步发现，以确定导致尼古丁摄入量变异I的基因。为此，我们将再次绘制影响尼古丁摄入量的染色体区域，但这一次是在一组小鼠身上，这将使我们能够更精确地定义包含影响尼古丁摄入量基因的基因组区域。随后，我们将进行选择性育种，培育出尼古丁摄入量不同的小鼠品系。选择过程应该产生富含等位基因的小鼠品系，这些等位基因与增加或减少尼古丁摄入有关。最后，我们将对选定的品系进行全基因组测序。我们将使用这些测序数据来确定通过作图识别的染色体区域是否通过选择过程得到丰富，并识别该区域内的所有变异。我们还将分析通过选择尼古丁消费而丰富的其他潜在染色体区域的序列数据。这种多层次的方法应该允许我们大大缩小对影响尼古丁摄取和潜在铅的变种的搜索范围 用于确定因果变异(导致尼古丁消费个体差异的功能变异)。

 DESCRIPTION (provided by applicant): Genetics clearly contributes to individual risk for nicotine dependence in humans and variations in nicotine sensitivity in experimental animals. In mice, several behavioral and physiological responses to nicotine have been demonstrated to be influenced by genetics. However, none of the specific genes that contribute to the genetic influence on nicotine sensitivity in mice have been identified. These genes remain an untapped source of information that almost certainly will improve our understanding of what drives individual differences in nicotine sensitivity. For example, the recent discovery that variants in human CHRNA5 are associated with risk for nicotine dependence in humans led to follow-up studies in rodents which not only helped to identify a specific neuronal pathway critical for controlling the level of nicotine consumption, but also demonstrated that this gene impacts individual differences in nicotine self-administration not by increased sensitivity to the reinforcng effects of nicotine at low doses but rather a lack of the loss of reinforcement at aversive doses. This is just one of many examples where the identification of a gene that contributes to individual variability in a phenotypic measure can lead to significant insights into the underlying biology of the measure. We previously have mapped chromosomal regions that harbor genes or genes that contribute to individual differences in oral nicotine intake in mice and it is the goal f this project to follow up this initial finding to identify the genes that contribute to variation i nicotine intake. For this, we will again map chromosomal regions that impact nicotine intake but this time in a panel of mice that will allow us to define with much greater precision the regions i the genome that harbor genes that impact nicotine intake. We will follow this up with selective breeding to produce lines of mice that differ in nicotine intake. The selection process should produce mouse lines that are enriched for alleles that are involved in increasing or decreasing nicotine intake. Finally, we will perform whole genome sequencing on the selected lines. We will use these sequencing data to establish whether the chromosomal regions identified through mapping are enriched through the selection process and to identify all variants within the region. We also will analyze the sequence data for other potential chromosomal regions that have been enriched through selection for nicotine consumption. This multi-tiered approach should allow us to substantially narrow the search for variants that influence nicotine intake and potentially lead to the identification of causal variants (functional variants that contribute to individual variabiity in nicotine consumption).