Mechanisms of microRNA dysregulation in Fragile X Syndrome

脆性X综合征（FXS）是遗传性智力障碍和遗传性智力障碍最常见的形式。 残疾和孤独症的单基因原因。它是由脆性X信使核糖核蛋白1的丢失引起的。 (FMR1/FMRP）蛋白。FMRP是一种RNA结合蛋白，通过多种方式调节靶mRNA， 例如控制mRNA定位、稳定化、编辑和/或翻译。翻译抑制 FMRP在神经元过程中尤其重要，在神经元过程中，蛋白质合成必须有序地控制 时尚.在不存在FMRP的情况下，翻译控制被破坏，导致树突状细胞的过度产生。 有助于FXS神经元未成熟棘和过度兴奋表型的蛋白质。正确翻译 FMRP的调节需要microRNA（miRNA）和RNA诱导的沉默复合物（RISC）。的risc 通过利用miRNA和靶mRNA之间的碱基匹配在转录后调节基因表达， 其允许靶mRNA的特异性识别。已经表明，在细胞中，miRNAs是失调的。 几个FXS模型;然而，没有研究无偏见地描述了人类中完整的mi RNA景观 FXS模型。FMRP-miRNA介导的基因调控的另一个未解决的方面是， 他们总是合作。最近的研究强调了FMRP在增强 因此，我假设FMRP的缺失改变了miRNA的格局， FMRP不仅协调miRNA介导的抑制，而且在某些情况下拮抗miRNA-RISC 保护誊本免受不当监管的机制。为了验证我的假设，我将进行实验 目标如下：（1）。测试FMRP的缺失是否改变了整体神经元miRNA的表达模式， miRNA掺入RISC，以及miRNA定位于神经元过程。2.）的情况。确定是否 FMRP-microRNA相互作用调节FMRP靶mRNA的全局和/或局部翻译。完成 为了实现这些目标，我需要在诱导多能干细胞培养、神经类器官和显微镜方面进行新的培训。 我的赞助人，加里·巴塞尔博士，在这些方法方面有专业知识，埃默里大学的科学界 医学院将为我提供一个良好的培训环境。成功完成本奖学金 该提案不仅揭示了miRNAs在FXS人类模型中失调的程度， 揭示FMRP和miRNA是否总是以单峰方式起作用。同样重要的是，这个项目 在Bassell博士的指导下，我将从一名分子癌症生物学家转变为一名独立的癌症研究者。 分子和细胞神经生物学家。

PROJECT SUMMARY: Fragile X Syndrome (FXS) is the most common form of both inherited intellectual disability and monogenic cause of autism. It is caused by the loss of Fragile X Messenger Ribonucleoprotein 1 (FMR1/FMRP) protein. FMRP, an RNA-binding protein, regulates target mRNAs through a variety of modes, such as controlling mRNA localization, stabilization, editing, and/or translation. Translational repression by FMRP is especially important in neuronal processes, where protein synthesis must be controlled in an orderly fashion. In the absence of FMRP, translational control is disrupted resulting in the over-production of dendritic proteins contributing to the FXS neuron phenotype of immature spines and hyperexcitability. Proper translation regulation by FMRP requires microRNAs (miRNAs) and the RNA-induced silencing complex {RISC). The RISC regulates gene expression post-transcriptionally by utilizing base matching between a miRNA and target mRNA, which allows for specific recognition of target mRNAs. It has been shown that miRNAs are dysregulated in several FXS models; however, no study has unbiasedly characterized the complete mi RNA landscape in human FXS models. Another unaddressed aspect of FMRP-miRNA mediated gene regulation is whether the interactions are always cooperative. Recent studies have highlighted an underappreciated role for FMRP in enhancing translation rather than suppressing it. Thus, I hypothesize that FMRP loss alters the miRNA landscape, and that FMRP not only coordinates miRNA-mediated repression, but in some cases antagonizes the miRNA-RISC machinery to protect transcripts from improper regulation. To test my hypotheses, I will conduct experiments aimed at the following goals: 1.) Test whether loss of FMRP alters global neuron miRNA expression patterns, miRNA incorporation into the RISC, and localization of miRNAs to neuronal processes. 2.) Determine whether FMRP-microRNA interactions regulate global and/or local translation of FMRP target mRNAs. To accomplish these aims, I will require new training in induced-pluripotent stem cell cultures, neural organoids, and microscopy. My sponsor, Dr. Gary Bassell, has expertise in these methods, and the scientific community of Emory University School of Medicine will offer me an excellent training environment. Successful completion of this fellowship proposal will not only reveal the extent to which miRNAs are dysregulated in human models of FXS, but also reveal whether FMRP and miRNAs always act in a unimodal manner. Of equal importance, this project coupled with Dr. Bassell's mentorship will allow me to transition from a molecular cancer biologist to an independent molecular and cellular neurobiologist.