MOLECULAR MECHANISMS UNDERLYING INTELLECTUAL DISABILITY CAUSED BY MUTATIONS IN THE CHROMATIN MODIFIER KDM5C

项目总结/摘要-研究项目 在编码转录调节因子赖氨酸脱甲基酶5C（KDM 5C）的基因中发现突变， 智力残疾（ID）患者。虽然KDM 5C中的功能缺失突变与 ID是清楚的，KDM 5C如何发挥作用来介导关键的神经元过程，因此KDM 5C的结果是： IDD机制的突变仍然未知。本提案的目的是了解 KDM 5C调控的基因表达程序与ID和其他疾病发生之间的关系 在患者中观察到的共病特征。我们将通过汇集多学科 研究团队在互补的分析工具和模型系统的专业知识，以测试两个假设。 目的1检验以下假设：使用KDM 5C诱导的ID的人iPSC衍生的体外细胞模型将 导致临床相关基因表达变化和神经元功能缺陷的鉴定。一 我们将使用的关键模型系统是iPSC衍生的脑类器官，其概括了结构和分子 胎儿大脑发育的各个方面，并且是用于确定胎儿大脑发育的根本原因的关键研究工具。 神经发育障碍事实上，使用体外类器官系统的分子和细胞研究使我们能够 在人体细胞中进行研究，这在体内是不可能的。iPSC和类器官将 从两个来源产生：（1）来自新招募的队列的KDM 5C诱导的ID患者的细胞 我们正在从中生成基因型-表型数据库的个体;（2）CRISPR-Cas9介导的 基因编辑以产生KDM 5C无效等位基因和缺乏组蛋白的公开的ID等位基因（KDM 5CA 388 P） 使用从通常发育的对照产生的现有iPSC系来测定脱甲基酶活性。我们将使用这个 系统结合联合收割机形态，功能和多OMICS方法，以确定患者的影响- KDM 5C相关突变。目的2验证了翻译效率的调节机制在翻译过程中起着重要作用的假设。 在哺乳动物系统中，KDM 5C的果蝇同源物对神经元的作用是保守的， for cognition认知.在这里，我们利用苍蝇和老鼠动物模型系统，既作为发现工具， 测试关于KDM 5C突变对认知影响的可能贡献者的假设。因为其他 遗传形式的ID改变了翻译，纠正这种缺陷已经在小鼠模型中显示出希望， 其他ID疾病，我们将测试是否改变翻译类似地发挥关键作用，在小鼠模型， KDM 5C诱导的ID。 这项工作是有意义的，因为我们将确定人类KDM 5C突变之间的病因学联系 拟议的研究在使用互补模型系统方面具有技术创新性， 最先进的基因组学技术，如单细胞转录组学（scRNA-seq）。从概念上讲， 创新地提出了翻译在KDM 5C诱导的ID中的作用。

PROJECT SUMMARY/ABSTRACT – RESEARCH PROJECT Mutations in the gene encoding the transcriptional regulator lysine demethylase 5C (KDM5C) are found in patients with intellectual disability (ID). While the direct link between loss of function mutations in KDM5C and ID is clear, how KDM5C functions to mediate critical neuronal processes, and therefore the consequence of mutations for mechanisms of IDD, remains unknown. The goal of this proposal is to understand the relationship between KDM5C-regulated gene expression programs and the occurrence of ID and additional comorbid features that are observed in patients. We will achieve this by bringing together a multi-disciplinary research team with expertise in complementary analytical tools and model systems to test two hypotheses. Aim 1 tests the hypothesis that the use of human iPSC-derived in vitro cell models of KDM5C-induced ID will result in the identification of clinically relevant gene expression changes and neuronal functional deficits. One key model system we will use is iPSC-derived cerebral organoids, which recapitulate structural and molecular aspects of fetal brain development and are a critical research tool used to define the underlying cause(s) of neurodevelopmental disorders. Indeed, molecular and cellular studies using in vitro organoid systems allow us to carry out studies in a human cell context that would simply not be possible in vivo. iPSCs and organoids will be generated from two sources: (1) Cells from patients with KDM5C-induced ID from a newly recruited cohort of individuals from which we are generating a genotype-phenotype database; (2) CRISPR-Cas9-mediated gene editing to generate a KDM5C null allele and a published ID allele (KDM5CA388P) that lacks histone demethylase activity using existing iPSC lines generated from typically developing controls. We will use this system to combine morphological, functional and multi-OMICS approaches to define the impact of patient- associated mutations in KDM5C. Aim 2 tests the hypothesis that the regulation of translation efficiency in neurons by the fly homolog of KDM5C is conserved in mammalian systems and that this function is important for cognition. Here we take advantage of fly and mouse animal model systems, both as discovery tools and to test hypotheses regarding possible contributors to the cognitive effects of mutations in KDM5C. Because other inherited forms of ID have altered translation and correcting this deficit has shown promise in mouse models of other ID disorders, we will test whether altered translation similarly plays a key role in a mouse model of KDM5C-induced ID. This work is significant because we will define the etiological links between mutations in human KDM5C and ID. The proposed studies are technologically innovative in the use of complementary model systems and state-of-the-art genomics techniques such as single cell transcriptomics (scRNA-seq). It is also conceptually innovative in proposing a role for translation in KDM5C-induced ID.