Defining post-transcriptional gene regulation in FMRP-deficiency usingmiRNA:target chimeras

脆性X综合征(FXS)是自闭症最常见的单基因病因 谱系障碍(ASD)是一组复杂的神经发育障碍 以社交互动中的核心诊断障碍为特征 交流，限制重复的行为和兴趣，以及协会 智障人士。FXS是由于FMR1表达不足所致 脆性X智力低下蛋白(FMRP)编码基因。早期的过度生长 神经元和过度不成熟的突触接触已经在 FXS儿童的大脑，以及Fmr1 KO小鼠模型。在一次 分子水平，异常过度的蛋白质合成，伴随着改变的产物 关键突触蛋白，与非典型神经和突触过度生长有关。 虽然FMRP的丢失会导致蛋白质合成过多，但机制改变 蛋白质合成产生不同表型的基因靶点选择性 FMRP缺乏症的发病机制尚不完全清楚。MicroRNAs(MiRNAs)很小 RNA可以选择性地靶向基因转录本在RNA中进行抑制- 诱导沉默复合体(RISC)。FXS被认为与监管不善有关 MiRNAs和miRNA介导的基因抑制超过15年，但范围广泛 对于靶向转录中的改变一直缺乏了解。我们建议 对RISC介导的基因打靶进行全基因组定量比较 在野生型和FMRP缺乏的环境中，使用小鼠和人类神经元。 在初步数据的指导下，我们将研究候选的let-7miRNA家族 验证Fmr1 KO中let-7 miRNA生物发生失调的假设 小鼠对促进生长的mRNAs及其下游的抑制作用 行为和神经解剖学表型。多管齐下的方法 机械性研究和确定基因靶点和途径的优先顺序 全基因组评估之后将进行干预，以评估功能 FXS相关表型的后果，目标是增强我们的 了解FMRP的功能并为其提供新的分子靶点 对FMRP缺乏所致表型的干预。

Fragile X Syndrome (FXS) is the most common monogenic cause of Autism spectrum disorder (ASD), a group of complex neurodevelopmental disorders characterized by core diagnostic impairments in social interactions and communication, restricted repetitive behaviors and interests, and an association with intellectual disability. FXS results from deficiency in expression of the FMR1 gene encoding Fragile X Mental Retardation Protein (FMRP). An early overgrowth of neurons and excessive immature synaptic contacts have been observed in brains of children with FXS, as well as in the Fmr1 KO mouse model. At a molecular level, aberrant excessive protein synthesis, with altered production of key synaptic proteins, is implicated in the atypical neural and synaptic overgrowth. While FMRP loss can lead to excessive protein synthesis, mechanisms altering the gene-target selectivity of protein synthesis to produce the distinct phenotypes of FMRP-deficiency are incompletely understood. MicroRNAs (miRNAS) are small RNAs which can selectively target gene transcripts for repression in the RNA- induced silencing complex (RISC). FXS has been linked to misregulation of miRNAs and miRNA-mediated gene repression for over 15 years, but broad knowledge of alterations in targeted transcripts has been lacking. We propose to carry out genome-wide quantitative comparisons of RISC-mediated gene targeting in the wildtype and FMRP-deficient setting using both mice and human neurons. Directed by preliminary data, we will investigate the candidate let-7 miRNA family to test the hypothesis that dysregulation of let-7 miRNA biogenesis in the Fmr1 KO mouse contributes to altered repression of pro-growth mRNAs and downstream behavioral and neuroanatomical phenotypes. A multipronged approach for mechanistic investigation and prioritizing gene targets and pathways from genome-wide assessments will be followed by intervention to assess the functional consequences for FXS-associated phenotypes with the goal of enhancing our understanding of FMRP function and providing new molecular targets for intervention in phenotypes resulting from deficiency of FMRP.