Delineating a role for histone modifications in Down syndrome using human cellular models

使用人类细胞模型描述组蛋白修饰在唐氏综合症中的作用

• 批准号: 10595812
• 负责人: Lindy Elise Barrett
• 金额: $ 28.5万
• 依托单位: BROAD INSTITUTE, INC.
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10595812
• 关键词: Aberrant DNA Methylation; Area; Automobile Driving; Blood Cells; CRISPR-mediated transcriptional activation; Cell Line; Cell model; Cells; Chromosome 21; DNA; DNA Maintenance; DNA Methylation; Data; Data Set; Development; Disease; Down Syndrome; Epigenetic Process; Euchromatin; Future; Gene Expression; Genes; Genetic Transcription; Glutamates; Histone H3; Human; Human Development; Immunoprecipitation; Induced pluripotent stem cell derived neurons; Intercistronic Region; Investigation; Lysine; Maps; Methylation; Molecular; Molecular Analysis; Neurodevelopmental Disorder; Neurons; Oncology; Pathway interactions; Patients; Pattern; Peripheral; Pharmacology; Phenotype; Physiological; Reader; Reporting; Reproducibility; Role; Sampling; Sotos syndrome; System; Testing; Tissues; Transcript; Transcriptional Regulation; Up-Regulation; base; cell type; clinically relevant; design; experimental study; fetal; genome-wide; histone demethylase; histone methyltransferase; histone modification; induced pluripotent stem cell; inhibitor; lymphoblastoid cell line; methylation pattern; novel; novel therapeutic intervention; novel therapeutics; recruit; stem cell model; therapeutic development

SUMMARY Down syndrome (DS), driven by an extra copy of chromosome 21, is associated with profound changes in genome-wide gene expression and DNA methylation, but underlying mechanisms remain incompletely resolved. Leveraging human induced pluripotent stem cell (iPSC) models to capture molecular mechanisms relevant for human development, we previously identified a significant decrease in the abundance of a specific histone modification, histone H3 lysine 36 dimethylation (H3K36me2), in DS patient cells compared with euploid controls; this finding was also highly reproducible across a panel of DS patient and euploid control lymphoblastoid cell lines, indicating the finding extends to some peripheral cell types. H3K36me2 is localized to euchromatin where it impacts transcriptional regulation and is essential for maintenance of DNA methylation via DNMT3A recruitment, particularly at intergenic regions. Notably, haploinsufficiency of the histone methyltransferase which catalyzes H3K36me2 drives a neurodevelopmental disorder called Sotos syndrome, characterized by reduced H3K36me2, transcriptional dysregulation and DNA hypomethylation. The profound developmental consequences of reduced H3K36me2 in Sotos syndrome supports the novel hypothesis that the reduced H3K36me2 we found in DS could also contribute to developmental abnormalities in this disease context. Our overall hypothesis is that reduced H3K36me2 in DS drives DNA hypomethylation and transcriptional dysregulation, and that normalization of H3K36me2 will partially rescue these phenotypes. In Aim I, we will test the hypothesis that decreased H3K36me2 drives DNA hypomethylation in DS, by generating genome-wide DNA methylation maps and integrating them with existing H3K36me2 gene occupancy and transcriptional datasets, all from the same DS patient and isogenic euploid control iPSC- derived glutamatergic neurons. Importantly, these experiments are designed to connect a well-characterized phenotype in DS (aberrant DNA methylation) with a novel molecular mechanism (reduced H3K36me2). In Aim II, we will test the hypothesis that normalizing H3K36me2 levels in DS patient iPSC-derived neurons can rescue DNA methylation phenotypes. These data would serve as proof-of-principle that inhibition or activation of specific epigenetic modifiers can reverse well-characterized phenotypes in DS, using physiologically relevant human cellular models. Collectively, our rigorous molecular analyses will elucidate novel mechanisms of epigenetic dysregulation in DS, which may ultimately inform on new therapeutic strategies for DS patients; they will also generate an essential roadmap for future studies to further investigate how reduced H3K36me2 and its normalization impacts iPSC-derived and peripheral blood cell phenotypes.

摘要 唐氏综合症(DS)由额外的21号染色体拷贝驱动，与 全基因组的基因表达和DNA甲基化，但潜在的机制仍然不完全 解决了。利用人类诱导多能干细胞(IPSC)模型捕捉分子机制 与人类发展相关，我们之前发现一种特定的 DS患者细胞中组蛋白修饰，组蛋白H3赖氨酸36二甲基化(H3K36me2)，与 整倍体对照；这一发现在DS患者和整倍体对照小组中也高度重复性 淋巴母细胞系，表明这一发现延伸到某些外周细胞类型。H3K36me2本地化到 常染色质影响转录调控，是维持DNA甲基化所必需的 通过DNMT3A招募，特别是在基因间区。值得注意的是，组蛋白的单倍性不足 催化H3K36me2的甲基转移酶导致一种名为Sotos综合征的神经发育障碍， 特点是H3K36me2减少，转录失调和DNA低甲基化。深奥的 Sotos综合征中H3K36me2基因缺失的发育后果支持新的假设 我们在DS中发现的H3K36me2基因的减少也可能导致这种疾病的发育异常 背景。我们的总体假设是DS中H3K36me2的减少导致DNA低甲基化和 转录失调和H3K36me2正常化将部分挽救这些 表型。在目标I中，我们将检验H3K36me2减少导致DNA低甲基化的假设 DS，通过生成全基因组DNA甲基化图谱并将其与现有的H3K36me2基因整合 占用和转录数据集，全部来自同一DS患者和同基因整倍体对照IPSC- 衍生的谷氨酸能神经元。重要的是，这些实验旨在连接一个特征良好的 DS(异常DNA甲基化)的表型具有新的分子机制(减少的H3K36me2)。在AIM II，我们将检验这一假设，即使DS患者IPSC来源的神经元中H3K36me2水平正常化可以 挽救DNA甲基化表型。这些数据将作为抑制或激活的原则证明 特定的表观遗传修饰物可以逆转DS的特征良好的表型，使用生理学方法 相关的人体细胞模型。总而言之，我们严格的分子分析将阐明新的机制 对DS患者表观遗传失调的研究，这可能最终为DS患者的新治疗策略提供信息； 他们还将为未来的研究提供必要的路线图，以进一步调查如何减少H3K36me2 其正常化会影响IPSC来源的表型和外周血细胞表型。