Epigenetics of Down Syndrome

唐氏综合症的表观遗传学

• 批准号: 9977004
• 负责人: Benjamin Tycko
• 金额: $ 126.01万
• 依托单位: HACKENSACK UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-13 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9977004
• 关键词: Address; Adult; Affect; Alleles; Alzheimer' s Disease; Aneuploidy; Architecture; Area; Autoimmunity; Autopsy; Bacterial Artificial Chromosomes; Binding Sites; Bioinformatics; Biological; Biological Assay; Biological Models; Brain; Cell Nucleus; Cells; Cerebrum; Chromatin; Chromosomal Duplication; Chromosomes; Critiques; DNA Methylation; Data; Development; Disease; Down Syndrome; Engineering; Epigenetic Process; Exhibits; Expression Profiling; Gene Dosage; Gene Expression; General Population; Genes; Genetic; Genetic Materials; Genetic Transcription; Genetic study; Genome; Genomics; Heart Abnormalities; Human; Individual; Intellectual functioning disability; Joints; Knock-out; Leukocytes; Life; Link; Lymphocyte; Malignant Neoplasms; Medical; Messenger RNA; Methylation; Modeling; Molecular; Mus; Mutation; Neuroglia; Neurons; Newborn Infant; Outcome; Paper; Pathogenesis; Pathway interactions; Pattern; Phenotype; Ploidies; Predisposition; Publishing; Quality of life; Recurrence; Research; Resistance; Shapes; Site; Specificity; Stains; Standardization; Syndrome; TF gene; Testing; Time; Tissues; Transgenes; Transgenic Model; Trisomy; Work; bisulfite sequencing; cell type; design; dosage; epigenetic profiling; epigenome; experimental study; fetal; gray matter; human tissue; improved; interstitial; mRNA Expression; methylation pattern; mouse Ts65Dn; mouse model; mutant; neoplastic; neuropsychiatric disorder; offspring; overexpression; response; success; transcription factor; transcriptome sequencing; whole genome

Achieving a better understanding of the pathogenesis of Down syndrome (DS; trisomy 21) is important for improving the quality of life of people with DS and for understanding major phenotypes, including intellectual disability, autoimmunity, cardiac defects, Alzheimer’s disease, and cancer susceptibility and resistance, which are prominent in DS and are also highly relevant to the general population. Recently we carried out epigenetic profiling, focusing on DNA methylation, in grey matter and purified neurons and glial cells from autopsy brains, as well as T-lymphocytes, from individuals with DS vs. matched normal controls. We found highly recurrent DS-specific differences in methylation patterns (DS-DM), and observed tissue-specificity of the DS-DM, onset of the altered methylation patterns at the fetal stage, and altered mRNA expression (DS-DE) of only a subset of the affected genes. We found that CpGs in specific classes of transcription factor binding sites (TFBS) were preferentially affected, implicating altered TFBS occupancy as a mechanism in shaping the patterns of DS-DM. Additionally, we carried out whole genome bisulfite sequencing (WGBS) on brains from mouse models of DS, compared to wild-type littermates, and found alterations in methylation patterns that significantly paralleled those in the human brains. Motivated by these findings, we now seek to answer three questions – all using well-controlled mouse models of DS carrying chromosomal triplications. First, to understand the molecular consequences of DS-DM we will identify DM genes in the mouse models and determine which of them have differential mRNA expression. We will address this question in purified cell types: T cells and GABAergic neurons. Second, we will test two hypotheses for the trans-acting mechanisms of DS-DM: (i) the abnormal methylation is due to over-expression of methylation pathway genes, including Dnmt3l and others, in the triplicated chromosome regions, and/or (ii) the abnormal patterns of methylation are shaped by overexpression of specific TF genes in the triplicated regions, leading to altered TFBS occupancy followed by altered CpG methylation in and around these sites. We will transfer segmental deletions and/or knockout alleles of individual genes into the DS mouse models to normalize gene dosage, and use WGBS and phenotyping to ask whether specific components of the DM and specific phenotypes are affected, respectively, in the offspring carrying the compound mutations. Third, we will apply state-of-the-art genomic assays to ask whether chromatin architecture within the cell nucleus is altered by the presence of the extra genetic material, and whether this alteration in turn affects DNA methylation, gene expression and phenotypes. Success of our project will identify effector and target genes for DS-DM and unravel the mechanisms underlying DS-DM. We expect that these data will significantly improve our understanding of DS pathogenesis and have broad implications for trans-acting genetic epigenetic interactions in other human developmental and neoplastic disorders that are associated with chromosomal aneuploidies.

更好地了解唐氏综合征(DS；21三体)的发病机制对 改善DS患者的生活质量并了解主要表型，包括智力 残疾、自身免疫、心脏缺陷、阿尔茨海默病、癌症易感性和耐药性，这些因素 在DS中突出，也与普通人群高度相关。最近我们进行了表观遗传学 在尸检大脑的灰质和纯化的神经元和神经胶质细胞中，重点是DNA甲基化， 以及来自DS患者和匹配的正常对照组的T淋巴细胞。我们发现高复发率 DS特异性甲基化模式差异(DS-DM)，并观察DS-DM的组织特异性，发病 胎儿期甲基化模式的改变，以及只有一个子集的mRNA表达改变(DS-DE 受影响的基因。我们发现，在特定类别的转录因子结合位点(TFBS)中的CPG 优先受影响，暗示TFBS占位改变是形成DS-DM模式的一种机制。 此外，我们对DS小鼠模型的大脑进行了全基因组亚硫酸盐测序(WGBS)， 与野生型窝种进行比较，发现甲基化模式的变化与 那些在人脑中的。在这些发现的激励下，我们现在试图回答三个问题--都是使用 携带染色体三联体的受控良好的DS小鼠模型。首先，要了解分子 DS-DM的后果我们将在小鼠模型中识别DM基因，并确定其中哪些基因具有 差异表达的基因。我们将在纯化的细胞类型中解决这个问题：T细胞和GABA能 神经元。其次，我们将检验DS-DM的反式作用机制的两个假说：(I)异常 甲基化是由于甲基化途径基因，包括Dnmt31和其他基因在 三倍体染色体区域，和/或(Ii)甲基化异常模式是由过度表达形成的 导致TFBS占有率发生改变，随后CpG发生改变 这些部位及其周围的甲基化。我们将转移节段性缺失和/或敲除等位基因 将单个基因导入DS小鼠模型以使基因剂量标准化，并使用WGBS和表型来询问 DM的特定成分和特定表型在后代中是否分别受到影响 携带复合突变。第三，我们将应用最先进的基因组分析来询问 细胞核内的染色质结构因额外遗传物质的存在而改变，并且 这种改变是否反过来影响DNA甲基化、基因表达和表型。我们的成功 该项目将确定DS-DM的效应基因和靶基因，并揭示DS-DM的潜在机制。我们 期望这些数据将显著提高我们对DS发病机制的理解，并具有广泛的 反式遗传表观遗传相互作用在其他人类发育和肿瘤中的意义 与染色体非整倍体相关的疾病。