Transcriptional Regulation of Stem Cell Differentiation into Motor Neurons

描述（申请人提供）： 在定义控制未指定的神经前体逐步分化为支配特定肌肉靶点的运动神经元的转录事件方面已经取得了相当大的进展。尽管取得了这些进展，但仍有许多关于这一过程的转录调控网络的知识有待了解。基于从ES细胞产生特定运动神经元亚型的同质制剂的能力，该项目将采取全球性的方法来定义运动神经元和其他脊髓神经元之间的转录差异。然后将鉴定的转录因子用于鉴定靶基因，从而迭代地定义转录网络。这项工作围绕三个目标展开。目标1。将使用已知的决定运动神经元或背侧中间神经元命运的转录因子来驱动ES细胞分化，以鉴定可能参与获得通用运动神经元身份的因子。目标二。将使用内在和外在的因素，驱动运动神经元的分化特征的特定列或池从小鼠ES细胞，以定义控制运动神经元亚型身份的transcrptional逻辑。这些基本进展将应用于目标3。脊髓性肌萎缩症（SMA）是一种发育性疾病，由运动神经元存活所需的蛋白质SMN水平降低引起。新的ES细胞系将来源于表达正常和降低水平的SMN的运动神经元，这些SMN从SMA小鼠模型中获得。将筛选这些疾病特异性ES细胞的转录谱差异。在这些筛选中被鉴定为潜在效应物的基因的功能测试将使用一组集中于运动神经元分化、存活和轴突生长的体外和体内测试系统进行。该项目还将为SMA的潜在治疗靶点提供新的方法。相关性研究脊髓中特定运动神经元群发育为支配特定肌肉的方式对于理解如何实现呼吸和运动的精确控制至关重要。这些研究将为理解为什么特定的运动神经元群在脊髓性肌萎缩症（SMA）等疾病患者中退化和死亡提供线索。这个项目将确定参与这一重要神经元群体的正常发育和病理变性的分子机制。

Description (provided by applicant): Considerable progress has been made in defining the transcriptional events that control the stepwise Differentiation of unspecified neural precursors into motor neurons that innervate specific muscle targets. Despite these advances, much remains to be learned of the transcriptional regulatory network that subtends this process. Based on the ability to generate homogeneous preparations of specific motor neuron subtypes from ES cells, this project will take a global approach to defining transcriptional differences between motor neurons and other spinal neurons. Transcription factors identified will then be used to identify target genes and thereby iteratively define transcriptional networks. The work is structured around three aims. Aim 1. will use transcription factors known to determine motor neuron or dorsal interneuron fate to drive ES cell differentiation, in order to identify factors potentially involved in the acquisition of generic motor neuron identity. Aim 2. will use intrinsic and extrinsic factors that drive the differentiation of motor neurons characteristic of specific columns or pools from mouse ES cells, to define the transcrptional logic that controls motor neuron subtype identity. These basic advances will be applied in Aim 3. to the study of Spinal Muscular Atrophy (SMA), a developmental disease that results from reduction in levels of a protein, SMN, that is required for motor neuron survival. New ES cell lines will be derived from motor neurons expressing normal and reduced levels of SMN, obtained from mouse models for SMA. These disease-specific ES cells will be screened for differences in transcriptional repertoire. Functional testing of genes identified as potential effectors in these screens will be performed using a panel of in vitro and in vivo test systems focused on motor neuron differentiation, survival and axon growth. The project should also provide new approaches to potential therapeutic targets in SMA. Relevance Studying the way in which specific groups of motor neurons in the spinal cord develop to innervate specific muscles is central to understanding how precise control of breathing and movement is achieved. These studies will provide clues for understanding why specific groups of motor neurons degenerate and die in patients with diseases such as spinal muscular atrophy (SMA). This project will identify molecular mechanisms involved both in normal development and pathologic degeneration of this important neuronal population.