Epigenetic Silencing of HSA21 in Down Syndrome

摘要 唐氏综合症是由21号染色体(HSA21)上的一组基因的三倍体引起的。具有以下特征的个人 DS均表现为某种程度的智力低下(MR)。MR被归因于 脑发育障碍(即神经发生)以及进行性细胞死亡 突触发生(即神经变性)。沉默三条HSA21染色体中的一条拯救了DS 但这种治疗方法实际上受到基因组编辑效率和能力的限制 以特异性靶向单个HSA21染色体。我们的初步研究表明了一部小说的可行性 一种改进的CRISPR方法，大大提高了HSA21和WE基因组材料的整合 还设计了一种专门针对单个HSA21拷贝的方法。我们现在提议 评估这些方法在人DS iPSC系中的效率的实验 分化为神经和少突胶质细胞状态。我们还将讨论这些干预措施的程度 将DS品系内的遗传和表观遗传表达与其等基因对应品系进行比较 以及DS细胞是否从功能角度(增殖、细胞死亡、线粒体 功能和氧化应激)。总体而言，如果成功，这些研究将克服两个根本障碍 需要从表观遗传学的方法治疗DS(和其他染色体异常)，并奠定 潜在动物研究的基础。

Summary Down syndrome arises from the triplication of a subset of genes on chromosome 21 (HSA21). Individuals with DS uniformly demonstrate some degree of mental retardation (MR). The MR has been attributed to impairments in brain development (i.e. neurogenesis) as well as progressive cell death with altered synaptogenesis (i.e. neurodegeneration). Silencing of one of the three HSA21 chromosomes rescues the DS phenotype but such a therapeutic approach is limited practically by the efficiency of genomic editing and ability to specifically target a single HSA21 chromosome. Our preliminary studies show the feasibility of a novel modified CRISPR approach which greatly enhances the integration of genomic material on HSA21 and we have also devised a means with which to specifically target a single HSA21 copy. We now propose experiments to assess the efficiency of these approaches in human DS iPSC lines and following their differentiation into neural and oligodendrocyte states. We will also address to what extent these interventions normalize both genetic and epigenetic expression within the DS lines compared to their isogenic counterparts and whether the DS cells are rescued from a functional perspective (proliferation, cell death, mitochondrial function and oxidative stress). Overall, if successful, these studies will overcome two fundamental hurdles needed to treat DS (and other chromosomal abnormalities) from an epigenetic approach and lay the foundation for potential animal studies.