Genetics of Alcohol Sensitivity in Drosophila

描述(申请人提供)：酗酒和酗酒是严重的公共卫生问题。在美国，酗酒影响了大约1400万人，每年的医疗费用为1840亿美元。人类对酒精中毒的遗传学研究一直具有挑战性，因为难以量化与酒精相关的表型和获取大样本，以及酒精中毒与其他行为和神经精神障碍的共同发病率、性别影响、人群混合以及对酒精的脆弱性和弹性机制的多样性。许多研究的结果表明，除了几个常见的等位基因外，许多不同的稀有等位基因可能会导致 不同的人群，表明与酒精相关的表型背后存在复杂的遗传结构。理解这种遗传结构需要一种综合的系统遗传学方法。果蝇提供了一个理想的模式系统，因为可以低成本、不受监管限制地饲养大量基因相同的个体，并且 的社区资源可用于复杂的遗传操作。此前，我们测量了40个野生近交系果蝇的乙醇敲除时间，并构建了与酒精敏感性和耐受性诱导相关的转录本模块。此外，我们围绕影响对酒精暴露的敏感性或抵抗力的基因建立了协变转录本的计算网络，这些基因是由P元素突变确定的。在我们下一阶段的研究计划中，我们将利用一种新的资源，果蝇遗传参考小组(DGRP)，它将使我们能够利用自然发生的变异，允许全基因组关联(GWA)分析，以提供dna多态和转录网络结构之间缺失的联系，识别eQTL，并指定与酒精诱导的转录网络相关的方向性(即顺式和反式调控效应)。 表型。DGRP是一个社区资源，由192个野生来源的自交系组成，这些自交系的基因组完全测序，所有分离的多态都是已知的。到目前为止，这些品系在所有表型上都是遗传可变的。我们将追求以下具体目标：(1)首次对192个DGRP品系进行酒精敏感性和耐受性的GWA研究，以确定与酒精敏感性和耐受性相关的多态，使用GWA分析和多元回归相结合的新型统计模型来生成基因型-表型预测，并通过对DGRP系与极端表型值杂交而来的高级杂交群体的个体果蝇进行基因分型来验证这些预测；(2)将来自极端DGRP品系的转录本丰度数据与GWA信息相结合，通过突变分析或RNAi击倒，利用有针对性的Hub基因中断来推导影响酒精敏感性和耐受性的原因遗传网络，并测试网络预测；(3)确定发育期间接触酒精在多大程度上改变了特定目标1和2中确定的遗传网络，并确定与酒精相关表型的基因型和环境相互作用有关的因果变异。AIM 3的动机是我们观察到，幼年时期的慢性酒精暴露会调节成年后对随后的酒精暴露的敏感性。拟议的研究将产生果蝇酒精敏感性遗传结构的全面系统遗传学蓝图，在此蓝图上可以叠加人类同源基因，以产生新的假说，为未来的后续研究指定候选中枢基因。

DESCRIPTION (provided by applicant): Alcohol abuse and alcoholism are significant public health problems. In the United States, alcoholism affects approximately 14 million people at a health care cost of $184 billion per year. Human genetic studies on alcoholism have been challenging due to difficulties in quantifying alcohol-related phenotypes and obtaining large sample sizes together with co-morbidity of alcoholism with other behavioral and neuropsychiatric disorders, gender effects, population admixture, and the diversity of mechanisms of vulnerability and resilience to alcohol. The results of many studies indicate that, in addition to a few common alleles, many different rare alleles may contribute to vulnerability in different populations, suggesting a complex genetic architecture that underlies alcohol-related phenotypes. Understanding this genetic architecture requires an integrative systems genetics approach. Drosophila presents an ideal model system, because large numbers of genetically identical individuals can be reared at low cost and without regulatory restrictions, and a plethora of community resources is available for sophisticated genetic manipulations. Previously, we measured ethanol knockdown time in 40 wild-derived inbred Drosophila lines and constructed modules of correlated transcripts associated with alcohol sensitivity and induction of tolerance. In addition, we built computational networks of covariant transcripts around genes that affect sensitivity or resistance to alcohol exposure identified by P-element mutations. During the next phase of our research program we will utilize a novel resource, the Drosophila Genetic Reference Panel (DGRP), that will enable us to capitalize on naturally occurring variation by allowing genome-wide association (GWA) analyses to provide the missing link between DNA polymorphisms and transcriptional network structure, identify eQTL and designate directionality (i.e. cis and trans regulatory effects) to transcriptional networks associated with alcohol induced phenotypes. The DGRP is a community resource, which was generated in our laboratories and consists of 192 wild-derived inbred lines with fully sequenced genomes in which all segregating polymorphisms are known. The lines are genetically variable for all phenotypes measured to date. We will pursue the following Specific Aims: (1) Perform the first GWA study of alcohol sensitivity and tolerance in the 192 DGRP lines to identify polymorphisms associated with alcohol sensitivity and tolerance, use novel statistical models that combine GWA analyses and multiple regressions to generate genotype-phenotype predictions, and validate such predictions by genotyping individual flies from an advanced intercross population derived by crossing DGRP lines with extreme phenotypic values; (2) Combine transcript abundance data from extreme DGRP lines obtained by deep RNA sequencing with GWA information to derive causal genetic networks affecting alcohol sensitivity and tolerance and test network predictions using targeted disruption of hub genes through mutational analysis or RNAi knock-down; (3) Determine to what extent exposure to alcohol during development alters the genetic networks identified in Specific Aims 1 and 2, and identify causal variants associated with genotype by environment interaction for alcohol-related phenotypes. Aim 3 is motivated by our observation that previous chronic alcohol exposure as larvae modulates sensitivity to subsequent alcohol exposures as adults. The proposed studies will result in a comprehensive systems genetics blueprint of the genetic architecture of alcohol sensitivity in Drosophila on which human orthologues can be superimposed to generate novel hypotheses that designate candidate hub genes for future follow-up studies.