FMRP Regulation of Gene Expression

基因表达的 FMRP 调控

• 批准号: 10250556
• 负责人: KIMBERLY M. HUBER
• 金额: $ 59.87万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10250556
• 关键词: 5' Untranslated Regions; Adult; Agonist; Alternative Splicing; Anxiety; Binding; Biochemical; Brain; Cells; ChIP-seq; Chromatin; Code; Cognition; Data; Dendrites; Developmental Delay Disorders; Disease; Elements; Epigenetic Process; Event; FMR1; FMRP; Fragile X Syndrome; Functional disorder; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Health; Hippocampus (Brain); Human; Impaired cognition; Inherited; Knockout Mice; Link; Long-Term Depression; Mediating; Messenger RNA; Methods; Modeling; Molecular; Mus; Neurons; Paper; Patients; Phosphorylation Site; Polyadenylation; Polyribosomes; Protein Biosynthesis; Proteins; RNA; RNA Splicing; RNA-Binding Proteins; Regulation; Resolution; Ribosomes; Seizures; Seminal; Site; Slice; Social Behavior; Speech Delay; Symptoms; Synapses; Translations; Triplet Multiple Birth; Work; autism spectrum disorder; autistic; base; epigenetic silencing; excitatory neuron; exon skipping; experimental study; gene product; genetic manipulation; mRNA Precursor; mouse model; nerve stem cell; nervous system disorder; neuronal cell body; neurophysiology; receptor; reconstitution; ribosome profiling; risk variant; social deficits; transcription factor; transcriptome; transcriptome sequencing; translation factor

The Fragile X Syndrome (FXS) is an inherited neurological disorder on the autism spectrum that is caused by expansion of CGG triplets in the 5' untranslated region (UTR) of FMR1, leading to its epigenetic silencing. In the absence of the FMR1 gene product FMRP, protein synthesis in the brain is excessive, which is correlated with several manifestations of the disorder including cognitive impairment, developmental delays, social deficits, seizures, etc. Elevated protein synthesis likely drives several of these pathophysiologies, thereby underscoring the importance of understanding FMRP-regulated translation. FMRP is an RNA binding protein that represses translation and does so, at least in part, by impeding ribosome translocation on specific mRNAs. How FMRP could stall ribosomes is unclear, although reconstitution experiments suggest that it could bind the ribosome and block interactions with essential translation factors. Our studies focused initially on identifying the mRNAs that are bound with FMRP-stalled ribosomes. By modifying transcriptome-wide ribosome profiling to determine rates of ribosome transit in the mouse hippocampus, we find that thousands of mRNAs are bound by slow moving or nearly completely stalled ribosomes. FMRP in particular is necessary to stall ribosomes on a number of specific mRNAs including several that, surprisingly, code for epigenetic and transcription factors. One of these mRNAs bound by FMRP-stalled ribosomes encodes SETD2, which catalyzes the chromatin mark H3K36me3 and which is elevated ~2.5 fold in Fmr1-deficient hippocampus. ChIP-seq demonstrates that in the absence of FMRP, H3K36me3 is rearranged on chromatin including in gene bodies where it modulates pre-mRNA processing. We find substantial mis-regulation of RNA slicing, particularly exon skipping events, which strongly link FXS to autism. Based on these and other data, we propose three multi-part specific aims: 1) determine whether FMRP stalls ribosomes at specific sites on mRNA, occurs in excitatory neurons, is alleviated by synaptic activity, and takes place in cell bodies and/or dendrites; 2) investigate whether depletion of SETD2 ameliorates FXS pathophysiology in model mice; 3) determine whether exon skipping occurs in excitatory neurons, microexon skipping in the autism risk gene CPEB4 links FXS to autism, and alteration of factors that mediate exon skipping can rescue biochemical features of FXS and autism.

脆性 X 综合征 (FXS) 是自闭症谱系中的一种遗传性神经系统疾病，由以下原因引起： CGG 三联体在 FMR1 的 5' 非翻译区 (UTR) 中扩展，导致其表观遗传沉默。在 缺乏 FMR1 基因产物 FMRP，大脑中的蛋白质合成过多，这与 该疾病的多种表现包括认知障碍、发育迟缓、社交缺陷、 癫痫发作等。蛋白质合成升高可能会驱动其中几种病理生理学，从而强调 了解 FMRP 监管翻译的重要性。 FMRP 是一种 RNA 结合蛋白，可抑制 翻译，并且至少部分地通过阻止特定 mRNA 上的核糖体易位来实现这一点。 FMRP如何 是否可以阻止核糖体尚不清楚，尽管重构实验表明它可以结合核糖体并 阻止与重要翻译因子的相互作用。我们的研究最初集中于识别 mRNA 与 FMRP 停滞的核糖体结合。通过修改转录组范围的核糖体分析来确定速率 通过对小鼠海马体中核糖体转运的研究，我们发现数千个 mRNA 被缓慢移动或 核糖体几乎完全停滞。 FMRP 尤其对于阻止核糖体在许多特定的 令人惊讶的是，mRNA 包括多种编码表观遗传和转录因子的 mRNA。这些 mRNA 之一 与 FMRP 停滞核糖体结合编码 SETD2，它催化染色质标记 H3K36me3，并且 在 Fmr1 缺陷的海马体中，该值升高约 2.5 倍。 ChIP-seq 证明在没有 FMRP 的情况下， H3K36me3 在染色质上重排，包括在基因体内调节前 mRNA 加工。我们 发现 RNA 切片的严重错误调节，特别是外显子跳跃事件，这与 FXS 密切相关 自闭症。基于这些和其他数据，我们提出了三个多部分具体目标：1）确定 FMRP 是否 使核糖体停滞在 mRNA 的特定位点，发生在兴奋性神经元中，通过突触活动减轻，并且 发生在细胞体和/或树突中； 2) 研究 SETD2 的耗尽是否会改善 FXS 模型小鼠的病理生理学； 3）确定兴奋性神经元、微外显子是否发生外显子跳跃 自闭症风险基因 CPEB4 中的跳跃将 FXS 与自闭症联系起来，以及介导外显子跳跃的因素的改变 可以挽救 FXS 和自闭症的生化特征。