Rapid identification of cocaine sensitivity genes using a novel reduced complexity cross

摘要 物质使用障碍(SUD)会导致发病率和死亡率的增加，并对 对受影响的个人和整个社会造成个人和经济负担。有相当多的证据 这种遗传学增加了患肥厚症的风险，但识别特定的基因变异一直受到疾病的阻碍。 人类的异质性、遗传复杂性和无法控制或解释环境暴露 人口。其中一些问题可以通过对啮齿动物模型的成瘾遗传学研究来解决。然而， 在啮齿动物种群中绘制图谱的标准方法通常会导致识别大的基因组区域，这些区域 需要相当大的努力来缩小范围，从而推迟或阻止对因果基因变体的识别。近期 技术和生物信息资源使利用杂交进行遗传图谱研究成为可能 在近亲交配的小鼠亚系之间(称为降低复杂性杂交或RCC)。近交系小鼠亚系 当近交系繁育群体在合作者或商业实体之间转移时，就会出现分歧。 在亲本菌株所在的基因组区域，多态在这些亚群之间分离 尚未变得固定，或由于遗传漂移，导致了几组在遗传上非常接近的菌株。 因此，虽然标准的自交系在数十万个基因座上彼此不同，但自交系的亚系 有数千个不同的基因座--其中只有一小部分是有功能的。这些特征加快了识别速度 存在表型差异的亚株中的致病基因。此方法已用于识别 可卡因敏感基因，但仅限于C57BL/6亚株。存在着数十个近亲交配的亚种 识别影响成瘾相关行为的基因的机会正在被错过。我们有 在C3H亚株C3H/Hej之间发现可卡因运动敏感性的显著表型差异 和C3H/HeNTac。在这个R21应用中，我们建议使用RCC来识别原因等位基因(S) 这些亚株的表型差异。我们还将检查亚株的特定药代动力学和剂量 使用药物自身反应表型并检查可卡因的奖赏和增强效应 管理范式。这些研究将建立每个C3H亚株的药物反应谱，并允许 美国开始探索因果等位基因改变行为的机制。

ABSTRACT Substance use disorders (SUD) result in increased risk of morbidity and mortality and impose substantial personal and financial burdens on affected individuals and society as a whole. There is considerable evidence that genetics increases the risk for SUDs, but identifying specific gene variants has been hampered by disease heterogeneity, genetic complexity and the inability to control or account for environmental exposures in human populations. Some of these issues can be overcome with addiction genetic studies in rodent models. However, standard methods of mapping in rodent populations often result in identification of large genomic regions that require considerable effort to narrow and thus delay or prevent identification of the causal gene variant. Recent technology and bioinformatic resources have made it possible to conduct genetic mapping studies using crosses between inbred mouse substrains (called Reduced Complexity Crosses or RCCs). Inbred mouse substrains diverge when inbred strain breeding colonies are transferred between collaborators or commercial entities. Polymorphisms segregate between these subpopulations at regions of the genome for which the parental strain has not yet become fixed, or from genetic drift, resulting in sets of strains that are genetically very closely related. Therefore, while standard inbred strains differ from each other at hundreds of thousands of loci, inbred substrains differ at thousands of loci – only a fraction of which will be functional. These characteristics expedite identification of causal genes in substrains for which phenotypic differences exist. This approach has been used to identify a cocaine-sensitivity gene but has been limited to C57BL/6 substrains. Dozens of inbred substrains exist and opportunities for identifying genes that influence addiction-related behaviors are being missed. We have identified a striking phenotypic difference in cocaine locomotor sensitivity between the C3H substrains, C3H/HeJ and C3H/HeNTac. In this R21 application, we propose to use a RCC to identify the causal allele(s) for the phenotypic differences in these substrains. We will also examine substrain-specific pharmacokinetic and dose response phenotypes and examine the rewarding and reinforcing effects of cocaine using the drug self- administration paradigm. These studies will establish a drug response profile for each C3H substrain and allow us to begin exploring mechanisms by which the causal allele alters behavior.