Epigenetic Regulation in a Cancer Associated Region

癌症相关区域的表观遗传调控

• 批准号: 7990429
• 负责人: MICHAEL Joseph HIGGINS
• 金额: $ 29.17万
• 依托单位: ROSWELL PARK CANCER INSTITUTE CORP
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7990429
• 关键词: 11p15.5; Address; Adult; Affect; Alleles; Beckwith-Wiedemann Syndrome; Binding; Binding Sites; Biological Assay; CCCTC-binding factor; CDKN1C gene; Childhood; Chromatin; Chromosomes; Complement; Defect; Development; Disease; EG Cell Line; Enhancers; Epiblast; Epigenetic Process; Exhibits; Fertilization; Gametogenesis; Gene Silencing; Genes; Genetic Transcription; Genome; Genomic Imprinting; Genomics; Grant; Growth; Human; Human Chromosomes; Human Genome; Inherited; Investigation; Knowledge; Lead; Length; Lesion; Light; Maintenance; Malignant Neoplasms; Mediating; Methylation; Mouse Strains; Mus; Mutant Strains Mice; Mutation; Nuclear; Nucleic Acid Regulatory Sequences; Parents; Patients; Placenta; Predisposition; Process; RNA Sequences; Regulation; Retinal Cone; Role; Site; Staging; Structure of primordial sex cell; Testing; Time; Tissues; Tumor Suppressor Genes; Untranslated RNA; Work; abstracting; cell type; developmental disease; genetic regulatory protein; genome-wide; imprint; insight; male; mammalian genome; metaplastic cell transformation; mouse model; novel; promoter; recombinase; research study; therapeutic development

DESCRIPTION (provided by applicant): Project Summary/Abstract Most human cancers show evidence of genome-wide epigenetic lesions. One common epigenetic alteration is loss of imprinting (LOI) which is defined as either biallelic expression or silencing of normally monoallelically expressed genes. Recently, several studies have provided compelling evidence that LOI has a causal role in cellular transformation. A large proportion of patients with Beckwith-Wiedemann syndrome (BWS), an imprinting disorder and cancer predisposition condition, exhibit loss of methylation (LOM) at the differentially methylated region in human chromosome 11p15.5 known as KvDMR1. This epimutation, which is also observed in several adult cancers, is associated with LOI (i.e., silencing) of the tumor suppressor gene CDKN1C. During the last 19 month grant period, we have completed studies that show that the KvDMR1 imprinting control region (ICR) contains both the promoter for the Kcnq1ot1 noncoding RNA (ncRNA) and sequences possessing repressive activity in enhancer-blocking assays. Moreover, we have shown that the epigenetic regulatory protein CTCF binds to the minimal repressive sequence in an allele-specific manner. We have also completed studies on our Kcnq1ot1 truncation mouse model which has not only demonstrated a critical role for the ncRNA in regulating imprinted expression, but has uncovered a second silencing mechanism specific for the tumor suppressor gene Cdkn1c. In combination with a Cdkn1c null allele, this truncation mouse has been instrumental in generating a novel mouse model that recapitulates several aspects of BWS. The Kcnqot1 truncation mouse has also allowed us to demonstrate that, while expression of the ncRNA is required for the establishment of nonequivalent nuclear localization of the KvDMR1 imprinted domain, it is dispensable later in development. The current proposal consists of 2 specific aims intended to further our understanding of the mechanism(s) of KvDMR1 function: (1) The CTCF binding sites in KvDMR1 will be deleted either alone or in combination with the Kcnq1ot1 truncation. These studies will determine the role for CTCF binding at this locus; (2) Expression of full length Kcnq1ot1 will be conditionally regulated at fertilization, and the Kcnq1ot1 promoter will be deleted at time points corresponding to the different developmental stages where paternal gene silencing takes place; these analyses will determine whether expression of the ncRNA is required during gametogenesis, and whether the ncRNA is necessary for the maintenance of imprinted expression once it is established. Since other imprinted domains containing growth regulating genes may be controlled in a similar fashion as the KvDMR1 subdomain, and it is likely that there are many other CTCF mediated chromatin insulators and ncRNAs in the mammalian genome, information derived from these studies will have widespread relevance to the epigenetics of cancer.

描述（由申请人提供）： 项目摘要/摘要大多数人类癌症显示了全基因组表观遗传病变的证据。一种常见的表观遗传学改变是印迹（LOI）的丧失，其定义为双重表达或正常单平表达基因的沉默。最近，一些研究提供了令人信服的证据，表明LOI在细胞转化中具有因果关系。在人类11p15.5中，大部分患有贝克维斯·韦德曼综合征（BWS）的患者是一种烙印和癌症易感疾病，在人类11p15.5中被称为kVDMR1的差异甲基化区域显示出甲基化（LOM）的损失。在几种成年癌症中也观察到的这种夸张与肿瘤抑制基因CDKN1C的LOI（即沉默）有关。在过去的19个月赠款期间，我们完成了研究表明，KVDMR1烙印控制区（ICR）既包含KCNQ1OT1非编码RNA（NCRNA）的启动子，也包含在增强子阻滞测定中具有抑制活性的序列。此外，我们已经表明表观遗传调节蛋白CTCF以特异性的方式与最小的抑制序列结合。我们还完成了对我们的KCNQ1OT1截断小鼠模型的研究，该模型不仅证明了NCRNA在调节印迹表达中的关键作用，而且还发现了对肿瘤抑制基因CDKN1C的第二种沉默机制。结合CDKN1C无效等位基因，这种截断小鼠对产生了一种新的小鼠模型，该模型概括了BW的几个方面。 KCNQOT1截断小鼠还允许我们证明，尽管NCRNA的表达是建立KVDMR1烙印域的非核定位所必需的，但在后来的开发中是可分配的。当前的建议由2个特定目的组成，旨在进一步了解KVDMR1函数的机制：（1）KVDMR1中的CTCF结合位点将单独删除或与KCNQ1OT1截断结合使用。这些研究将确定CTCF在该基因座的结合的作用。 （2）全长KCNQ1OT1的表达将在受精时有条件调节，并且将在与父亲基因沉默发生的不同发育阶段相对应的时间点上删除KCNQ1OT1启动子；这些分析将确定在配子发生过程中是否需要NCRNA的表达，以及一旦建立印迹表达，是否需要维持NCRNA。由于其他含有增长基因的印迹域可能与KVDMR1亚域相似，并且在哺乳动物基因组中可能还有许多其他CTCF介导的染色质绝缘子和NCRNA，因此这些研究的信息将与这些研究的信息相关。