CircRNAs and CNS Gene Transfer

摘要：环状RNA(CircRNAs)是一类新兴的RNA分子，由于其不能与核酸外切酶结合而具有延长表达的潜力。最近对CircRNA生物发生的研究发现，在人类中，ALU重复等反向重复序列位于大量经历环化的外显子的两侧，并表明这些顺式元件以及剪接机制对于它们的环化是必不可少的。在哺乳动物的大脑中，CircRNA似乎高度丰富，并受到发育和可塑性的动态调节。特别是，在突触和神经元分化和发育过程中，它们似乎是丰富的。尽管取得了这些令人振奋的进展，但还没有研究人工合成CircRNA生物发生的系统，也没有研究神经疾病模型的系统。目前这项提案的具体目标是设计CircRNA表达系统，研究影响CircRNA在大脑中生物生成效率的因素，并利用这些系统来询问C9orf72六核苷酸重复序列扩展小鼠的额颞叶痴呆(FTD)和肌萎缩侧索硬化症(ALS)模型中剪接的解除调控和RNA诱导的神经毒性。能够破坏在这些小鼠模型中看到的神经毒性RNA焦点的CircRNA可以使FTD/ALS的治疗方法的设计成为可能，在FTD/ALS中，C9orf72的扩展是普遍存在的，并被认为是致病的。总体而言，目前的提议将有助于开发在动物模型中有效地进行CircRNA生物发生的新策略，这可能有助于了解影响哺乳动物大脑中CircRNA生物发生的因素，并引入一种基于环状RNA的新的核酸疗法。

ABSTRACT: Circular RNAs (circRNAs) are an emerging class of RNA molecules with potential for prolonged expression due to their inaccessibility to exonucleases. Recent studies dissecting circRNA biogenesis have found inverted repeat sequences such as ALU repeats in humans, flanking a large number of exons that are subject to circularization and have shown these cis-elements as well as splicing machinery are essential for their circularization. In the mammalian brain, circRNAs appear to be highly abundant and dynamically regulated by development and plasticity. In particular, they appear to be enriched at the synapses and during neuronal differentiation and development. Despite these exciting advances, no systems for studying biogenesis of synthetic circRNAs in the brain and models of neurological disease. Specific aims for the current proposal are focused on engineering circRNA expression systems, studying factors affecting circRNA biogenesis efficiency in the brain, and utilizing these systems to interrogate deregulation of splicing and RNA-induced neurotoxicity seen in a C9orf72 Hexanucleotide Repeat Expansion mouse model of Frontotemporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). CircRNAs capable of disrupting the neurotoxic RNA foci seen in these mouse models may enable design of therapeutics for FTD/ALS, where the C9orf72 expansion is prevalent and believed to be causative. Overall, the current proposal will help develop new strategies for efficient biogenesis of circRNAs in animal models, which are likely to help understand factors affecting circRNA biogenesis in the mammalian brain as well as usher in a new class of nucleic acid therapeutics based on circular RNAs.