Genetic Factors Underlying Risk for Methamphetamine Intake and Associated Traits

在没有药物暴露的情况下，可以在动物模型中通过 许多策略，例如通过使用选择性繁殖的动物品系。然而，建模风险并不是 即使在非人类模型中，过程也很简单，因为风险不是一个单一的结构；因此，多基因 而且必须考虑非遗传因素，风险因素可能因个体而异。甲基苯丙胺 (MA)有强烈的兴奋作用，鼓励使用；但经过多年的研究，大致有效 药物尚未确定。我们已经开发出一种由小鼠品系组成的遗传动物模型 有选择地为高和低自愿饮用MA而饲养(MAHDR和MALDR)，目的是确定 使用MA的遗传风险和保护因素。对于与MA至关重要的多个MA性状，这些线是不同的 使用障碍。我们在小鼠10号染色体上定位了一个区域，该区域占遗传基因的50% MA消费的差异，并获得了为示踪胺相关受体提供证据的数据 1基因Taar1作为MA采食量的数量性状基因。此应用程序侧重于并购风险中的Taar1 使用，以及发现与Taar1突变(Taar1m1J)相关的风险增加的遗传修饰物 这是一个不起作用的受体的密码；TAAR1。这将通过确定 影响Taar1m1J/m1J基因对MA摄入量影响的转录组的个体差异。我们的 这些发现将指导研究治疗MA使用障碍的新机制。三个目标是 建议。在目标1中，CRISPR-Cas9 Taar1m1J等位基因取代了小鼠，其中TAAR1功能已经恢复 具体地说，在MAHDR小鼠中(MAHDR-Taar1+/+)将与未替换的对照组(MAHDR-Taar1 M1j/m1j)。可靠区分MAHDR和MALDR选系的MA相关性状，这两个品系在Taar1中存在差异 研究 与糖精(作为一种调味品和自然奖励)和奎宁(作为一种调味品)也将进行表演。行为 对等位基因交换有效性的评估将使用TAAR1特异性激动剂进行测试。在目标2中， RNA-Seq数据将用于重组近交系小鼠(BXD)的基因表达网络分析 RI)，均为Taar1m1J/m1J基因。其目标是找出能减少影响的基因修饰物。 Taar1m1J/m1J基因型对MA摄入量的影响，因为它们可能导致新的治疗方法。伏隔核 (NAC)内侧壳将因其在药物奖励中的关键作用而被初步研究。在目标3中，RNA-Seq结果、数据 基本搜索(DrugBank、广泛研究所连接地图、NCBI上的PubChem)和发布的结果将是 用来提名神经靶点，以操纵它们对MA摄取的影响，并最终识别新的 治疗。这项研究的长期目标是确定可以减少MA使用的新疗法，基于 关于与个体遗传易感性“标记”的匹配，由特定的基因星座组成。

Risk as a population measure can be assessed in animal models in the absence of drug exposure through a number of strategies, such as via the use of selectively bred animal lines. However, modelling risk is not a straightforward process, even in non-human models, since risk is not a unitary construct; thus, multiple genetic and non-genetic factors must be considered, and risk factors likely vary across individuals. Methamphetamine (MA) has powerful euphoric effects that encourage use; but, after many years of research, broadly effective medications have not been identified. We have developed a genetic animal model comprised of lines of mice selectively bred for high and low voluntary MA drinking (MAHDR and MALDR), with the goal of identifying genetic risk and protective factors for MA use. These lines differ for multiple MA traits critically relevant to MA use disorders. We mapped a region on mouse chromosome 10, that accounts for >50% of the genetic variance in MA consumption, and obtained data that provide evidence for the trace amine-associated receptor 1 gene, Taar1, as a quantitative trait gene for MA intake. This application is focused on Taar1 in risk for MA use, and on the discovery of genetic modifiers of the increased risk associated with a Taar1 mutation (Taar1m1J) that codes for a non-functional receptor; TAAR1. This will be accomplished through the identification of individual differences in the transcriptome that impact the effect of the Taar1m1J/m1J genotype on MA intake. Our findings will guide the examination of novel mechanisms for the treatment of MA use disorders. Three aims are proposed. In Aim 1, CRISPR-Cas9 Taar1m1J allele replaced mice, in which TAAR1 function has been restored specifically in MAHDR mice (MAHDR-Taar1+/+) will be compared to non-replaced controls (MAHDR-Taar1 m1J/m1J). MA-related traits that reliably differentiate the MAHDR and MALDR selected lines, which differ in Taar1 genotype, will be examined (i.e., MAHDR are all Taar1m1J/m1J and MALDR are Taar1+/+ or Taar1+/m1J). Studies with saccharin (as a tastant and a natural reward) and quinine (as a tastant) will also be performed. Behavioral assessment of the effectiveness of the allele swap will be tested using a TAAR1-specific agonist. In Aim 2, RNA-Seq data will be used in gene expression network analyses in recombinant inbred strains of mice (BXD RI) that all possess the Taar1m1J/m1J genotype. The goal is to identify genetic modifiers that reduce the impact of the Taar1m1J/m1J genotype on MA intake, because they could lead to new treatments. The nucleus accumbens (NAc) medial shell will be initially studied due for its critical role in drug reward. In Aim 3, RNA-Seq results, data base searches (DrugBank, Broad Institute Connectivity Map, PubChem at NCBI) and published results will be used to nominate neural targets to manipulate for their impact on MA intake and ultimately to identify novel treatments. The long-term goal of this research is to identify novel treatments that could reduce MA use, based on matching to individual genetic susceptibility “markers”, comprised of specific constellations of genes.