Generation and analysis of new mouse models to determine novel therapeutic targets for Down syndrome-associated cognitive deficits

摘要 人类21号染色体(21三体)的一个额外拷贝的存在与唐氏综合征(DS)有关， 这是人类最常见的活生生的染色体改变。在美国，DS有一个 发病率约为每691名新生儿中有1名，DS患者表现出许多临床表型； 神经系统的参与是最繁重的负担之一。今天，人类21三体仍然是领先的 发育迟缓和智力残疾的遗传原因具有几乎普遍的外显性。有效 对这种临床表现的治疗将是变革性的，因为这些治疗方法可以深刻地 提高DS患者的生活质量。基于盛行的假设，特定的表型 DS的发生受到人类21号染色体(Hsa21)上特定基因剂量增加的影响， 对特定的基因组片段，即人类节段性三体进行了详细的研究，以建立 基因型-表型关系，最终目标是识别剂量敏感的致病基因 可以作为治疗靶点。然而，由于缺乏足够的资金，这些努力受到严重阻碍。 提供信息的节段性三体病例数。幸运的是，基于进化的另一种更有成效的选择 人类和老鼠之间的保护也一直在进行，这种方法使得基因 剖析努力，以更快的速度前进。例如，分析小鼠的DYRK1A基因同源基因 证明该基因是DS相关发育认知缺陷的致病决定因素； 随后，这些结果成为唯一成功的涉及发育的临床试验的基础。 认知缺陷与Hsa21基因同源。为了进一步进行基因解剖工作，我们开发了一种 大量小鼠突变体在Hsa21同源区域携带不同的染色体重排。 在本申请的目标1中，我们将利用这些小鼠突变体，并通过使用CRISPR- 介导性基因组工程加强我们识别新的剂量敏感致病基因的努力 DS的潜在发展认知缺陷，其人类同源基因可作为治疗靶点 以及DYRK1A基因。除了通过增加基因剂量发挥作用外，人类21三体可能还具有 其他影响表型的方式，例如通过改变核结构，从而改变基因表达。在……里面 本应用程序的目标2，我们将使用小鼠模型来验证第二个假设。我们相信……的成功 我们提出的项目将对DS的总体研究和DS相关的研究产生变革性的影响 尤其是发展性认知缺陷。

ABSTRACT The presence of an extra copy of human chromosome 21 (trisomy 21) is associated with Down syndrome (DS), and this is the most common live-born chromosomal alteration in humans. In the United States, DS has an incidence rate of approximately 1 in 691 newborns, and individuals with DS exhibit many clinical phenotypes; nervous system involvement is among the most burdensome. Today, human trisomy 21 remains a leading genetic cause of developmental delays and intellectual disabilities with near universal penetrance. Effective treatments for such clinical manifestations would be transformative because these treatments could profoundly improve the quality of life for individuals with DS. Based on the prevailing hypothesis that particular phenotypes of DS are affected by the dosage increase of specific genes on human chromosome 21 (Hsa21), triplications of particular genomic segments, i.e., human segmental trisomies, have been studied in detail to establish genotype–phenotype relationships with the ultimate goal of identifying dosage sensitive causative genes that can serve as therapeutic targets. However, such efforts have been severely hampered by the lack of an adequate number of informative segmental trisomy cases. Fortunately, amore fruitful alternative based on the evolutionary conservation between humans and mice has also been pursued, and this approach has allowed the genetic dissection efforts to advance much more rapidly. For example, analyses of the DYRK1A gene ortholog in mice demonstrated that this gene is a causative determinant for DS-associated developmental cognitive deficits; subsequently, these results served as the basis for the only successful clinical trials involving developmental cognitive deficits and orthologous Hsa21 genes. To further the genetic dissection efforts, we have developed a large number of mouse mutants carrying different chromosomal rearrangements in Hsa21 orthologous regions. In Aim 1 of this application, we will utilize these mouse mutants and develop new mutants by using CRISPR - mediated genome engineering to enhance our efforts to identify novel dosage sensitive causative genes underlying developmental cognitive deficits in DS, whose human orthologs can serve as therapeutic targets along with the DYRK1A gene. Besides acting through a gene dosage increase, human trisomy 21 may have other ways of influencing phenotypes, such as by altering the nuclear architecture and thus gene expression. In Aim 2 of this application, we will test this second hypothesis by using mouse models. We believe the success of our proposed project will have a transformative impact on research on DS in general and on DS-associated developmental cognitive deficits in particular.