CircRNAs and CNS Gene Transfer

摘要：环状RNA （circRNAs）是一类新兴的RNA分子，由于其无法接近外切酶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，像ALU重复序列这样的反向重复序列位于大量环状外显子的两侧，并且表明这些顺式元件以及剪接机制对其环状化至关重要。在哺乳动物大脑中，环状rna似乎非常丰富，并受发育和可塑性的动态调节。特别是，它们似乎在突触和神经元分化和发育过程中富集。尽管有这些令人兴奋的进展，但还没有研究大脑中合成环状rna的生物发生和神经系统疾病模型的系统。目前的具体目标是集中在工程circRNA表达系统，研究影响大脑中circRNA生物发生效率的因素，并利用这些系统来研究在额颞叶痴呆（FTD）和肌萎缩性侧索硬化症（ALS）的C9orf72 Hexanucleotide Repeat扩增小鼠模型中发现的剪接解除和rna诱导的神经毒性。在这些小鼠模型中，能够破坏神经毒性RNA病灶的CircRNAs可能有助于设计FTD/ALS的治疗方法，其中C9orf72扩增是普遍存在的，并且被认为是致病的。总的来说，目前的建议将有助于在动物模型中开发环状rna高效生物发生的新策略，这可能有助于了解哺乳动物大脑中影响环状rna生物发生的因素，并开创一类基于环状rna的新型核酸治疗方法。

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.