Molecular Genetics of Nucleolar Dominance

核仁优势的分子遗传学

• 批准号: 7086249
• 负责人: CRAIG Stuart PIKAARD
• 金额: $ 28.57万
• 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/7086249
• 关键词: Arabidopsis; DNA methylation; acetylation; chromatin; cytosine; gene induction /repression; genetic promoter element; genetic transcription; histones; immunologic assay /test; methylation; methyltransferase; molecular genetics; nucleolus; plant genetics; ribosomal RNA; small interfering RNA; transcription factor

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(申请人提供)：核仁优势描述了在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，表观遗传开关涉及DNA甲基化、组蛋白甲基化和组蛋白乙酰化的协同变化，控制着激活/沉默的决定。利用拟南芥(A.thaliana)和拟南芥(A.arenosa)的杂交，短期目标是测试rRNA基因启动子DNA甲基化、组蛋白去乙酰化和组蛋白H3赖氨酸9(H3K9)甲基化在维持沉默的自我强化循环中各自位于彼此上游的假设。核仁优势所需的两个组蛋白脱乙酰酶(一个位于核仁中)、一个DNA甲基转移酶和几个甲基胞嘧啶结合蛋白已经存在。沉默所需的其他染色质修饰蛋白将通过RNAi介导的基因敲除来鉴定。这些活性的生化特性将被确定，并将使用染色质免疫沉淀、蛋白质-蛋白质相互作用分析和细胞学定位来检验它们在沉默基因上相互作用的假设。将在发育期间和新形成的杂交品种中测试沉默活动在建立和维持过程中的参与情况。特定启动子胞嘧啶甲基化是沉默的关键这一假设也将得到检验。这些努力将有助于实现理解核仁优势是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甲基酶活性是生存所必需的。在人类中，DNA甲基转移酶的突变会导致ICF综合征，组蛋白去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，可以沉默肿瘤抑制基因。通过剖析染色质介导的核仁显性沉默的机制，我们希望有助于理解并最终有助于对涉及异常基因表达的疾病的治疗。