Epigenetic Regulation of Heterochromatin Condensation in Huntington's Disease

亨廷顿病异染色质凝聚的表观遗传调控

基本信息

批准号：
8187357
负责人：
HOON RYU
金额：
$ 24.81万
依托单位：
BOSTON UNIVERSITY MEDICAL CAMPUS
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-07-01 至 2016-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8187357
关键词：
Affect American Autopsy Behavioral Binding Biological Assay Biological Markers Biological Markers Brain Brain Diseases CAG repeat CREB-binding protein Cell Death Cell Nucleus Chorea Code Cognitive Confocal Microscopy Corpus striatum structure DNA DNA Binding Data Dementia Development Disease Progression Enzyme Gene Epigenetic Process Exons Functional disorder Future Gene Expression Gene Silencing Genes Genetic Transcription Genome Glutamine Heterochromatin Heterozygote Histone Acetylation Histone H3 Histones Human Huntington Disease Hypermethylation Indium Inherited Injury Knock-out Knockout Mice Lead Libraries Link Longitudinal Studies Measurement Mediating Methods Methylation Methyltransferase Methyltransferase Gene Modification Molecular Mus Mutation Nerve Degeneration Neurodegenerative Disorders Neurons Onset of illness Pathogenesis Patients Phenotype Physical condensation Promoter Regions Protein Deficiency Proteins Regulation Reporting Research Risk Role SET Domain SETDB1 gene Sequence Analysis Symptoms Testing Therapeutic Transgenic Mice Transgenic Organisms Two-Hybrid System Techniques astrogliosis brain tissue chromatin immunoprecipitation chromatin remodeling disease-causing mutation effective therapy genome sequencing human CREBBP protein human Huntingtin protein image reconstruction insight middle age mouse model mutant nervous system disorder neurochemistry new therapeutic target novel novel therapeutic intervention pre-clinical promoter research study transcription factor

项目摘要

DESCRIPTION (provided by applicant): Huntington's disease (HD) is an incurable progressive autosomal-dominant neurological disorder caused by expanded CAG repeats coding for glutamine in the huntingtin (Htt) gene but it is not known how this mutation causes neurodegeneration. We recently discovered that alterations of ERG- associated protein with SET domain (ESET) expression and hypermethylation of histone H3K9 correlate with transcriptional dysfunction and neurodegeneration in two different transgenic mouse models of HD. Furthermore, in experiments using CREB binding protein (CBP) knockout mice, we found that CBP deficiency leads to histone hypermethylation and transcriptional deregulation by freeing Ets-2 to bind and activate the ESET gene thereby linking CBP deficiency to histone hypermethylation and neuronal degeneration. Our preliminary data shows that that brain CBP levels are reduced in HD transgenic mice and we confirmed, as reported by others, that mutant htt sequesters CBP. We hypothesize that mtHtt sequesters CBP resulting in greater availability of free Ets-2 to bind the ESET gene promoter region and increase ESET transcription. Increased ESET transcription in turn leads to hypermethylation of histone H3K9, transcriptional dysfunction, heterochromatin condensation and neurodegeneration in HD. We theorize that the trimethylated histone H3K9 (TMH3K9) mediates the epigenetic and transcriptional dysregulation that underlies disease progression of transgenic HD mice. We propose to test our hypothesis through three specific aims: Specific Aim 1: To determine under what mechanisms mtHtt and CBP modulates expression of the ESET gene, a histone H3K9 specific methyltransferase, and leads to chromatin remodeling. Specific Aim2: To examine how ESET modulates hyper-trimethylation of H3K9 (TMH3K9) and results in heterochromatin condensation and gene silencing. We will analyze the TMH3K9-dependent heterochromatin condensation by confocal microscopy combining deconvolution and 3-dimentional reconstruction of images. We will identify what genomes are silenced or modulated by TMH3K9 using ChIP and full genome sequencing analysis. Specific Aim 3: To cross mice genetically deficient in CBP (heterozygote and knockout) and ESET transgenic mice with the HD mice to determine the relationship among alterations of HMT gene expression, TMH3K9, and neuropathological phenotype and survival of crossed mice. Our proposed study will provide new insights and molecular mechanisms on the role of chromatin remodeling and gene silencing in the pathogenesis of HD. Considering a fact that epigenetic regulation is a strong candidate method from a therapeutic perspective, our mechanistic study will contirbute to finding of the novel therapeutic target and epigenetic biomarker in HD. PUBLIC HEALTH RELEVANCE: Huntington's disease (HD) is a fatal progressive hereditary neurological disease caused by mutations of the huntingtin (Htt) gene but it is not known how this mutation leads to nerve cell death. Changes in proteins called histones, which bind to DNA and regulate gene expression, are suspected to be involved but little is known about how this occurs. In this regard, our study focuses on enzymes and genes involved in controlling how histones interact with DNA and control gene expression. This research could lead to the development of novel biological markers for HD onset and progression and will provide new information about how DNA and its associated proteins are organized in the nucleus of neurons. This finding will allow us to develop a new therapeutic approach that contributes to preclinical and human trials in the future.

描述（由申请人提供）：亨廷顿氏病（HD）是一种无法治愈的渐进式常染色体主导性神经系统疾病，这是由huntingtin（HTT）基因编码谷氨酰胺的扩展引起的，但不知道该突变会导致神经变性。我们最近发现，在两个不同的HD的转基因小鼠模型中，ERG相关蛋白与组蛋白H3K9的SET结构域（ESET）表达和组蛋白H3K9的高甲基化的变化与转录功能障碍和神经变性相关。此外，在使用CREB结合蛋白（CBP）基因敲除小鼠的实验中，我们发现CBP缺乏症通过释放ETS-2来结合和激活ESET基因，从而导致组蛋白的高甲基化和转录失调，从而将CBP缺乏症与组型高甲基化和神经元化和神经元之间联系起来。我们的初步数据表明，HD转基因小鼠中脑CBP水平降低，我们证实，正如其他人所报道的那样，突变的HTT HTT隔离CBP。我们假设MTHTT隔离CBP，导致更大的自由ETS-2可用来结合ESET基因启动子区域并增加ESET转录。 ESET转录反过来又导致组蛋白H3K9，转录功能障碍，异染色质缩合和神经变性的高甲基化。我们认为三甲基化组蛋白H3K9（TMH3K9）介导了转基因HD小鼠疾病进展的表观遗传和转录失调。我们建议通过三个特定目的检验假设：具体目标1：确定MTHTT和CBP在哪些机制下调节ESET基因的表达，是ESET基因的表达，一种组蛋白H3K9特异性甲基转移酶，并导致染色质重塑。特定目标2：检查ESET如何调节H3K9（TMH3K9）的高三甲基化，并导致异染色质凝结和基因沉默。我们将通过共焦显微镜结合反卷积和图像的三维重建来分析TMH3K9依赖性异染色质凝结。我们将使用芯片和完整的基因组测序分析确定TMH3K9沉默或调节了哪些基因组。具体目的3：要跨小鼠在遗传上缺乏CBP（杂合子和敲除）和ESET转基因小鼠与HD小鼠，以确定HMT基因表达，TMH3K9，TMH3K9和神经病理学表型和跨小鼠的存活之间的关系。我们提出的研究将提供有关染色质重塑和基因沉默在HD发病机理中的作用的新见解和分子机制。考虑到从治疗的角度来看，表观遗传调节是一种有力的候选方法，我们的机械研究将纪念在HD中发现新型的治疗靶标和表观遗传学生物标志物。公共卫生相关性：亨廷顿氏病（HD）是由亨廷顿蛋白（HTT）基因突变引起的致命进行性遗传神经系统疾病，但尚不清楚这种突变如何导致神经细胞死亡。怀疑与DNA结合并调节基因表达的蛋白质的变化被怀疑参与其中，但对这种情况的发生知之甚少。在这方面，我们的研究重点是控制组蛋白与DNA和控制基因表达的酶和基因。这项研究可能导致用于HD发作和进展的新型生物学标志物的发展，并将提供有关在神经元细胞核中如何组织DNA及其相关蛋白的新信息。这一发现将使我们能够开发出一种新的治疗方法，该方法将来有助于临床前和人类试验。