Molecular Genetics of Nucleolar Dominance

核仁优势的分子遗传学

• 批准号: 7210537
• 负责人: CRAIG Stuart PIKAARD
• 金额: $ 27.75万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7210537
• 关键词: Animals; Arabidopsis; Binding; Binding Proteins; Biochemical; Biological Assay; Biological Models; Cell Nucleolus; Chromatin; Classification; Complex; Cytosine; DNA Methylation; DNA Methyltransferase; DNA Modification Methylases; Data; Deacetylation; Development; Disease; Epigenetic Process; Funding; Gene Expression; Gene Silencing; Genes; Genetic Transcription; Goals; HDAC1 gene; Hand; Histone Acetylation; Histone Deacetylase; Histone Deacetylation; Histone H3; Histones; Human; Hybrids; Knockout Mice; Link; Localized; Lysine; Maintenance; Mediating; Methylation; Methyltransferase; Modeling; Modification; Molecular Genetics; Mutation; Plants; Protein Binding Domain; Proteins; RNA Interference; Recruitment Activity; Research Personnel; Rett Syndrome; Ribosomal RNA; Role; Small Interfering RNA; Specificity; Switch Genes; Syndrome; Testing; Transgenes; Trichostatin A; Tumor Suppressor Genes; Yeasts; chromatin immunoprecipitation; demethylation; density; derepression; knock-down; programs; promoter; protein protein interaction; rRNA Genes; tumor

DESCRIPTION (provided by applicant): Nucleolar dominance describes the transcription of one parental set of rRNA genes, and the silencing of the other parental set, in a plant or animal inter-species hybrid. Recent evidence shows that an epigenetic switch involving concerted changes in DNA methylation, histone methylation and histone acetylation controls the activation/silencing decision. Using Arabidopsis suecica, the hybrid of A. thaliana and A. arenosa, the shortterm goal is to test the hypothesis that rRNA gene promoter DNA methylation, histone deacetylation and histone H3 lysine 9 (H3K9) methylation are each upstream of one another in a self-reinforcing cycle that maintains silencing. Two histone deacetylases (one localized in the nucleolus), one DNA methyltransferase and several methylcytosine binding proteins required for nucleolar dominance are already in hand. Additional chromatin modifying proteins required for silencing will be identified using RNAi-mediated gene knockdowns. Biochemical specificities of these activities will be determined and the hypothesis that they interact at silenced genes will be tested using chromatin immunoprecipitation, protein-protein interaction assays and cytological localization. Involvement of silencing activities in both establishment and maintenance will be tested during development and in newly formed hybrids. The hypothesis that methylation of specific promoter cytosines is key to silencing will also be tested. These efforts will help achieve the long-term goal of understanding how nucleolar dominance is established and enforced. DNA methylation and chromatin modifications are required for proper development. In knockout mice, DNA methyltransferase and histone H3K9 methylase activities are essential for viability. In humans, mutations in a DNA methyltransferase causes ICF syndrome and mutations in a histone deacetylase associated methylcytosine binding protein causes Rett syndrome. DNA methylation is also frequently elevated in tumors and can silence tumor suppressor genes. By dissecting mechanisms of chromatin-mediated silencing in nucleolar dominance, we hope to contribute to the understanding, and ultimately the treatment, of disorders involving aberrant gene expression.

描述（由申请人提供）：核仁优势描述了植物或动物种间杂交中一组亲本 rRNA 基因的转录，以及另一组亲本 rRNA 基因的沉默。最近的证据表明，涉及 DNA 甲基化、组蛋白甲基化和组蛋白乙酰化协同变化的表观遗传开关控制着激活/沉默决策。使用拟南芥（Arabidopsis suecica）（拟南芥和拟南芥的杂交种），短期目标是检验这一假设：rRNA 基因启动子 DNA 甲基化、组蛋白脱乙酰化和组蛋白 H3 赖氨酸 9 (H3K9) 甲基化在一个维持沉默的自我强化循环中各自处于上游。两种组蛋白脱乙酰酶（一种位于核仁中）、一种 DNA 甲基转移酶和核仁优势所需的几种甲基胞嘧啶结合蛋白已经在手。沉默所需的其他染色质修饰蛋白将通过 RNAi 介导的基因敲低来鉴定。将确定这些活性的生化特异性，并使用染色质免疫沉淀、蛋白质-蛋白质相互作用测定和细胞学定位来测试它们在沉默基因上相互作用的假设。沉默活动在建立和维持过程中的参与将在开发过程中和新形成的杂交体中进行测试。特定启动子胞嘧啶的甲基化是沉默的关键的假设也将得到测试。这些努力将有助于实现了解核仁优势如何建立和实施的长期目标。 DNA 甲基化和染色质修饰是正常发育所必需的。在基因敲除小鼠中，DNA 甲基转移酶和组蛋白 H3K9 甲基化酶活性对于生存能力至关重要。在人类中，DNA 甲基转移酶的突变会导致 ICF 综合征，而组蛋白脱乙酰酶相关的甲基胞嘧啶结合蛋白的突变会导致 Rett 综合征。 DNA 甲基化在肿瘤中也经常升高，并且可以沉默肿瘤抑制基因。通过剖析核仁优势中染色质介导的沉默机制，我们希望有助于理解并最终治疗涉及异常基因表达的疾病。