TRANSCRIPTION AND RNA BINDING IN FRAGILE X SYNDROME

脆性 X 综合征中的转录和 RNA 结合

• 批准号: 6613926
• 负责人: Daniel Reines
• 金额: $ 17.25万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6613926
• 关键词: DNA methylation; RNA binding protein; acetylation; acyltransferase; chemical structure function; chromatin; fragile X syndromes; gene induction /repression; genetic promoter element; genetic regulation; histones; human genetic material tag; human tissue; immunoprecipitation; intermolecular interaction; molecular pathology; nucleic acid repetitive sequence; nucleic acid structure; patient oriented research; sex linked trait; site directed mutagenesis; transcription factor; transfection

Description: Fragile X syndrome is the most common form of inherited mental retardation. It results from loss of function of the FMR1 gene product. Virtually all cases are due to the specific transcriptional silencing of FMR1 -- hence, the syndrome can be considered a transcriptional disease. Silencing is an indirect consequence of the expansion to more than 200 copies, of a CGG repeat (normal modal size of 30) in FMR1's 5'-untranslated region. Expansion results in the aberrant de novo methylation of cytosines both in CG dinucleotides within the repeat, and in the neighboring upstream CpG islands in the FMR1 promoter. Hypermethylation is thought to be a proximal cause of the transcriptional inactivity of FMR1 in patients. However the molecular mechanism by which methylation leads to loss of transcription of FMR1 is unknown. Patient FMR1 is packaged in hypoacetylated histones H3 and H4, another characteristic of transcriptionally silent loci. Drugs that reverse the methylation state of FMR1 DNA result in a relative hyperacetylation of histones H3 and H4 at FMR1 and restore transcription. A current model of methylation-mediated gene repression suggests that recruitment of histone deacetylases to the promoter via methyl cytosine binding proteins establish a closed chromatin environment at mutant FMR1. The long range objective of this project is to understand the molecular mechanism of transcriptional silencing of patient FMR1, and to ultimately reverse it. Aim 1 will characterize transcription factors, including histone acetyltransferase activities, that drive normal FMR1 promoter function. Aim 2 will identify repression complexes that bind methylated DNA and deacetylate histones in mutant, expanded FMR1 alleles. Aim 3 will test the idea that histone acetylation is important for FMR1 transcription by exogenously expressing histone acetyltransferase and directing it to the mutant, methylated FMR1 promoter. Promoter occupancy will be evaluated in patient cells with intermediate states of remodeled chromatin. Results obtained from this experimental system will allow identification of the steps involved in transcription of a clinically important gene residing in its natural chromosomal context.

描述：脆弱的X综合征是继承心理的最常见形式 迟钝。它是由于FMR1基因产物的功能丧失而导致的。 几乎所有情况都是由于FMR1的特定转录沉默引起的 - 因此，综合征可以视为转录疾病。沉默 是将CGG扩展到200多册的间接结果 在FMR1的5'-非翻译区域中重复（正常模态大小为30）。扩张 导致CG中的细胞霉素的从头甲基化的异常 重复中的二核苷酸以及在附近的上游CPG群岛中 在FMR1启动子中。高甲基化被认为是近端的原因 患者FMR1的转录不活动。但是分子 甲基化导致FMR1转录损失的机制为 未知。患者FMR1被包装在低乙酰化组蛋白H3和H4中 转录静音基因座的另一个特征。逆转的药物 FMR1 DNA的甲基化状态导致相对的高乙酰化 FMR1的组蛋白H3和H4并恢复转录。当前的模型 甲基化介导的基因抑制表明组蛋白的募集 通过甲基胞嘧啶结合蛋白对启动子的脱乙酰基酶建立 突变体FMR1处的闭合染色质环境。远程目标 项目是了解转录沉默的分子机制 患者fmr1的患者，并最终将其逆转。 AIM 1将表征 转录因子，包括组蛋白乙酰转移酶活性， 驱动正常的FMR1启动子功能。 AIM 2将识别镇压综合体 在突变体中结合甲基化的DNA和脱乙酰基组蛋白，膨胀的FMR1 等位基因。 AIM 3将测试组蛋白乙酰化对 FMR1通过外源表达组蛋白乙酰基转移酶和 将其引导到突变体的甲基化FMR1启动子。发起人占用者 在具有重塑染色质的中间状态的患者细胞中进行评估。 从该实验系统获得的结果将允许识别 属于临床重要基因的转录的步骤 它的天然染色体环境。