The FMR1 CGG repeat as functional element and therapeutic target in Fragile X associated disorders

FMR1 CGG 重复序列作为脆性 X 相关疾病的功能元件和治疗靶点

• 批准号: 10271293
• 负责人: Peter K Todd
• 金额: $ 52.18万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-25 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10271293
• 关键词: 5' Untranslated Regions; Antisense Oligonucleotides; Biological Assay; Biological Models; CGG repeat; CRISPR/Cas technology; Cell Line; Data; Dendrites; Disease; Elements; FMR1; FMR1 repeat; FMRP; FXTAS; Fragile X Premutation; Fragile X Syndrome; Gene Expression Regulation; Genetic Transcription; Goals; Human; Human Genome; Impairment; Inherited; Initiator Codon; Intellectual functioning disability; Knock-in Mouse; Learning; Long-Term Depression; Memory; Metabotropic Glutamate Receptors; Microsatellite Repeats; Modeling; Mus; Nerve Degeneration; Neurobiology; Neuronal Plasticity; Neurons; Open Reading Frames; Pathogenesis; Pathway interactions; Patients; Phenotype; Phosphorylation; Physiologic pulse; Play; Process; Protein Biosynthesis; Proteins; Receptor Activation; Regulation; Repetitive Sequence; Reporter; Role; Series; Short Tandem Repeat; Site; Small Interfering RNA; Synaptic plasticity; System; Testing; Translations; age related neurodegeneration; autism spectrum disorder; base; cryptic protein; genome-wide; human disease; human embryonic stem cell; improved; induced pluripotent stem cell; innovation; mouse model; nervous system disorder; novel strategies; novel therapeutics; prevent; response; synaptic function; therapeutic development; therapeutic target; tool

The FMR1 repeat as functional element and therapeutic target in Fragile X disorders. Short Tandem repeat (STR) expansions cause ~50 inherited neurological diseases. However, disease associated loci represent only a small fraction of the ~3 million STRs present in the human genome. Despite their importance in human disease, the broader question of what intrinsic roles these repetitive elements play in normal neurobiology is largely unexplored. We recently discovered a conserved and native function for CGG repeats in the 5’ UTR of FMR1. This repeat expands in Fragile X Syndrome (FXS, a common cause of autism and intellectual disability) and Fragile X-associated Tremor/Ataxia Syndrome (FXTAS, an age related neurodegenerative disorder). At normal and expanded sizes, FMR1 CGG repeats trigger translation of multiple cryptic proteins in the absence of an AUG start codon (CGG RAN translation). We recently described how CGG repeats and RAN translation act as an upstream open reading frame (uORF) to impede translation of the fragile X protein, FMRP. Using a combination of reporter assays as well as RAN translation blocking antisense oligonucleotides (RAN ASOs) in human neurons, we found that both the CGG repeats and RAN translation inhibit FMRP synthesis basally. This inhibition is alleviated by metabotropic glutamate receptor (mGluR) activation, which underlies a form of synaptic plasticity important for learning and memory and implicated in Fragile X-associated disorders. Based on these findings, our central hypothesis is that RAN translation and tandem microsatellite repeats have native functions in the regulation of the genes in which they reside, and that aberrancies in these native functions contribute to human disease. Our goals in this project are 3 fold: 1) Determine the mechanisms by which CGG repeats and RAN translation regulate FMRP synthesis, 2) investigate what consequences result from disrupting this regulatory loop in both mouse models and human neurons, and 3) evaluate whether ASOs can be used to simultaneously suppress RAN translation and activate FMRP synthesis in FXS and FXTAS human neurons as a step towards novel therapeutic development.

FMR1在脆弱的X疾病中重复为功能元素和治疗靶标。 短串联重复（STR）扩展导致〜50种遗传神经系统疾病。然而， 与疾病相关的局部局部仅占约300万个Str中的一小部分 人基因组。尽管它们在人类疾病中的重要性，但更广泛的问题是什么 这些重复元素在正常神经生物学中起着固有的作用，这在很大程度上是意外的。我们 最近在FMR1的5'UTR中发现了CGG重复的保守和天然函数。 这种重复在脆弱的X综合征中扩展（FXS，自闭症和智力的常见原因 残疾）和脆弱的X相关震颤/共济失调综合征（FXTAS，与年龄相关的 神经退行性障碍）。在正常和扩展的尺寸下，FMR1 CGG重复触发 在没有Aug Start密码子（CGG RAN）的情况下，多种加密蛋白的翻译 翻译）。我们最近描述了CGG重复和运行翻译如何作为上游 开放式阅读框（UORF）阻碍了脆弱X蛋白FMRP的翻译。使用 记者的组合以及跑步的翻译阻塞反义寡核苷酸 （RAN ASOS）在人类神经元中，我们发现CGG重复和翻译 基本抑制FMRP合成。代谢型谷氨酸接收器可以缓解这种抑制作用 （mglur）激活，它是一种突触可塑性形式的基础，对学习和 记忆并与脆弱的X相关疾病有关。根据这些发现，我们的中心 假设是RAN翻译和串联微卫星重复序列具有天然功能 对其居住的基因的调节，以及这些天然功能中的异常 有助于人类疾病。我们在这个项目中的目标是3倍：1）确定机制 通过该CGG重复并进行翻译调节FMRP合成，2）研究什么 后果是由于小鼠模型和人类中的这种调节循环而造成的 神经元和3）评估是否可以使用ASO简单地抑制RAN FXS和FXTAS人神经元中的FMRP合成并激活FMRP合成，作为迈向的一步 新型热发育。