Transcriptional Regulation of Stem Cell Differentiation into Motor Neurons

描述(由申请人提供)： 在定义转录事件方面已经取得了相当大的进展，这些转录事件控制着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。尽管取得了这些进展，但对于参与这一过程的转录调控网络仍有许多需要了解的地方。基于从胚胎干细胞产生特定运动神经元亚型的同质制剂的能力，该项目将采取一种全球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。确定的转录因子将被用来识别目标基因，从而反复定义转录网络。这项工作围绕三个目标展开。目的1.将利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细胞的分化，以确定可能与获得通用运动神经元身份有关的因素。目的2.将利用内在和外在因素驱动特定柱或池的运动神经元从小鼠胚胎干细胞分化，以确定控制运动神经元亚型识别的跨转录逻辑。这些基本进展将应用于目标3.脊髓肌萎缩症(SMA)的研究，这是一种由于运动神经元生存所需的蛋白质SMN水平降低而导致的发育性疾病。新的ES细胞系将来自运动神经元，表达正常和降低水平的SMN，从SMA小鼠模型获得。这些疾病特异的ES细胞将被筛选出转录谱系的差异。在这些筛选中被确定为潜在效应者的基因的功能测试将使用一组体外和体内测试系统进行，重点是运动神经元分化、存活和轴突生长。该项目还应为SMA的潜在治疗靶点提供新的方法。研究脊髓中特定运动神经元的发育方式以支配特定肌肉的相关性，对于理解如何实现对呼吸和运动的精确控制至关重要。这些研究将为理解脊髓性肌萎缩症(SMA)等疾病患者特定运动神经元退化和死亡的原因提供线索。该项目将确定这一重要神经元群体的正常发育和病理性退化所涉及的分子机制。

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.