A Novel Approach to Molecular Cell Pathologies of Human Down Syndrome and DS-AD

摘要 唐氏综合症(DS)，或21三体(T21)，是儿童认知障碍的一种非常常见的原因， 还会影响人的一生，增加患先天性心脏病、病毒易感性、 白血病，以及代谢、自身免疫和自闭症谱系障碍等疾病。此外，由于 患有DS的人寿命更长，我们现在知道大多数人都会患上早发性阿尔茨海默病(AD)。因此， 了解微小21号染色体的三个副本如何增加非DS患者的患病风险 人口具有广泛的重要性，尤其是对于AD这一紧迫的医学挑战。T21如何识别 影响特定的某些细胞类型导致DS的各个方面受到所有 人，以及DS的遗传和表型复杂性。因此，迫切需要改进的方法来识别 T21对特定细胞类型和组织的核心作用，以及涉及的相应基因途径。我们有 在DS iPS细胞中开发了一种可诱导的染色体沉默系统，允许采用“简化论”的方法， 保持其他变量不变，同时只操纵21号染色体的过度表达。在第一笔资金中 期间，我们验证了该系统在纠正DS和DS中已知的造血细胞发病机制的有效性 现在已经将其扩展到研究神经发生和血管生成，我们将在这里进一步研究。我们的 进展包括一项重大进展，因为我们已经识别出XIST“迷你基因”，它抑制聚集的基因在 只是一个很小的染色体区域，我们显示的是“唐氏综合症临界区”。这项创新已经 广泛的翻译含义，并将用于多种方式，包括与APP和AD有关的。一 SubAim还将测试这种方法对较小的染色体复制障碍的原理证明，如在 自闭症。我们的主要焦点是“剖析”T21对全基因组途径和细胞表型的影响，以及 区分特定细胞类型的持续功能效应与不同细胞类型的形成。我们的方法 可以定义T21过度表达的直接和直接影响，而不是组织中的边缘差异 它们在分化和病理上已经分化，因此在细胞中的根效应的下游。我们 将调查T21细胞影响什么，何时影响，以及至关重要的是，何时影响是可以预防的或 可逆的。这些知识是向药物开发目标提供信息的关键。这项工作也可以推进 更长远的前景是，“染色体疗法”最终可能提供一种治疗策略。最后，这一点 这项工作也对理解基因组平衡、基因表达的协调水平具有广泛的基础影响 整个基因组中的基因。 。

ABSTRACT Down Syndrome (DS), or Trisomy 21 (T21), is a highly common cause of cognitive disability in children, and also impacts individuals throughout life, by increased risks of congenital heart disease, viral susceptibility, leukemia, and conditions such as metabolic, autoimmune and autism spectrum disorders. Furthermore, as individuals with DS live longer, we now know that most develop early-onset Alzheimer Disease (AD). Hence, understanding how three copies of tiny chromosome 21 elevates risks of conditions that afflict the non-DS population is broadly important, especially for the pressing medical challenge of AD. Identification of how T21 impacts specific certain cell-types to cause various aspects of DS has been hampered by variation between all people, and the genetic and phenotypic complexity of DS. Thus, a critical need is for improved ways to identify core effects of T21 on specific cell types and tissues, and the corresponding gene pathways involved. We have developed an inducible chromosome silencing system in DS iPS cells that allows a “reductionist” approach, keeping other variables constant while manipulating just chromosome 21 over-expression. In the first funding period, we validated the utility of this system to correct the known hematopoietic cell pathogenesis in DS and now have extended this to study neurogenesis and angiogenesis, which we will further investigate here. Our progress includes a major advance, as we have identified XIST “minigenes” which repress clustered genes in just a small chromosomal region, which we show for the “Down syndrome critical region”. This innovation has broad translational implications and will be used to in multiple ways, including in relation to APP and AD. One sub-aim will also test proof-of-principle of this approach for smaller chromosome duplication disorders, as in autism. Our main focus is to “dissect” the impact of T21 on genome-wide pathways and cell phenotypes, and distinguish ongoing functional effects in a given cell-type versus formation of different cell types. Our approach can define the immediate and direct effects of T21 over-expression, rather than marginal differences in tissues that have diverged in differentiation and pathology, and thus are far downstream of the root effects in cells. We will investigate what cells T21 impacts, when it impacts, and, critically, when effects are preventable or reversible. Such knowledge is key to inform targets for drug development. This work also may advance the longer-term prospects that “chromosome therapy” may eventually provide a therapeutic strategy. Finally, this work also has broad basic impact for understanding genome balance, the coordinated levels of expression for genes throughout the genome. .