In vivo reprogramming reactive astrocytes into functional neuorons by microRNA-124 in the injured spinal cord

项目摘要： 脊髓损伤（SCI）是一种破坏性的神经系统疾病，经常损害患者的日常功能 一辈子都是SCI治疗的主要障碍之一是如何恢复失去的神经功能。 尽管数十年的研究努力，目前的策略，包括干细胞移植，并没有导致 成功的临床治疗。因此，迫切需要开发新的技术来治疗SCI。这 一个研究小组最近开发了一种创新的方法，将反应性星形胶质细胞重新编程为功能性星形胶质细胞。 通过注射表达单个神经转录因子的病毒颗粒原位修复脑神经元 NeuroD 1进入成年小鼠皮质（Guo等人，Cell Stem Cell，2014年最佳文章）。这项建议会 将这种尖端的体内重编程技术引入SCI。特别是，PI建议转换为 通过强制表达神经元特异性microRNA将内源性反应性星形胶质细胞转化为功能性神经元 （miRNA）miR-124。目前大多数体内重编程研究，包括该团队的研究， 通过使用表达神经原性转录因子的病毒载体进行;以及通过使用表达神经原性转录因子的病毒载体进行体内神经元转化， miRNAs尚未报道。 miRNAs是一种小的非编码RNA，在神经发育和疾病中起着关键作用。的 miRNA的功能可能是强大的，因为一个miRNA可以通过独特的功能调节许多靶基因。 不完善的碱基配对机制。此外，它们的小尺寸（~22个核苷酸）使它们对人具有吸引力。 因为它们可以容易地穿透组织并被靶细胞吸收。MiR-124播放 在神经发生、神经元分化和成熟中起关键作用，这使其成为 神经元重编程因此，在本提案中，PI将检验以下假设： miR-124可以在受损的脊髓中将反应性星形胶质细胞转化为功能性神经元， 神经元可以整合到局部神经元回路中并促进SCI后的功能恢复。的PI 提出了两个具体的目的：1）确定反应性星形胶质细胞转化为神经元后，miR-124 2）确定miR-124转化的神经元的功能整合及其对动物神经元的影响。 挫伤性脊髓损伤后的行为完成此处的拟议研究将显示miR-124介导的 胶质-神经元转化，并为这种小RNA分子的治疗应用奠定基础 作为一种合成药物此外，这一提议的成功将可能导致一部小说 治疗SCI以及其他神经系统疾病，如创伤性脑损伤（TBI）， 肌萎缩侧索硬化症（ALS）。

Project Summary: Spinal cord injury (SCI) is a devastating neurological disorder that often impairs the daily function of patients for their entire life. One of the major obstacles in treating SCI is how to restore the lost neuronal functions. Despite decades of research efforts, current strategies including stem cell transplantation have not resulted in a successful clinical therapy. Therefore, there is an urgent need to develop novel technology to treat SCI. This research team has recently developed an innovative approach to reprogram reactive astrocytes into functional neurons in situ for brain repair by injecting viral particles expressing a single neural transcription factor NeuroD1 into the adult mouse cortex (Guo et al., Cell Stem Cell, BEST of 2014 article). This proposal will introduce this cutting-edge in vivo reprogramming technology into SCI. In particular, the PI proposes to convert endogenous reactive astrocytes into functional neurons by forced expression of a neuronal specific microRNA (miRNA) miR-124. Most of current in vivo reprogramming studies including the one from this team have been done by using viral vectors expressing neurogenic transcription factors; and in vivo neuronal conversion by miRNAs has not been reported. MiRNAs are small non-coding RNAs that play pivotal roles during neural development and diseases. The miRNA function could be potent in that one miRNA may regulate many target genes through the unique imperfect base-pairing mechanism. Furthermore, their small size (~22 nucleotides) makes them attractive for therapeutic application since they may easily penetrate tissues and be taken up by target cells. MiR-124 plays critical roles in neurogenesis, neuronal differentiation and maturation, which makes it an ideal candidate for neuronal reprogramming. Therefore, in this proposal, the PI will test the hypothesis that forced expression of miR-124 can convert reactive astrocytes into functional neurons in the injured spinal cord, and that converted neurons can integrate into the local neuronal circuitry and promote functional recovery after SCI. The PI proposes two specific aims: 1) To determine conversion of reactive astrocytes into neurons by miR-124 after SCI; 2) To determine functional integration of miR-124-converted neurons and their effects on animal's behavior after contusive SCI. Completion of the proposed study here will show feasibility of miR-124-mediated glia-neuron conversion in vivo and lay out foundation for therapeutic application of this small RNA molecules as a synthetic drug in the future. In addition, the success of this proposal will potentially lead to a novel therapeutic treatment for SCI as well as other neurological diseases such as traumatic brain injury (TBI) and amyotrophic lateral sclerosis (ALS).