Function of Olig2-Regulated Genes in Spinal Motor Neuron Development

描述（由申请人提供）：中枢神经系统（CNS）中神经回路的形成取决于未分化干细胞和祖细胞以定型方式产生不同类别神经元和神经胶质细胞的能力。我们的主要目标是了解细胞周期调控和分化的一般方面如何与细胞命运决定协调的分子细节。先前，我们鉴定了一种称为Olig2的bHLH类转录抑制因子，其由脊髓中的运动神经元（MN）祖细胞选择性表达，并参与协调MN发育的三个关键特征：MN特异性基因表达、细胞周期退出和一般神经元分化。由于Olig2作为一个阻遏物的功能，我们假设，Olig2必须通过其关闭其他重要的调控基因，本身控制的命运，增殖和分化的干细胞和祖细胞在中枢神经系统的表达能力直接MN的形成。这些基因的身份目前尚不清楚。使用鸡和小鼠脊髓中基因功能的体外和体内测定，我们将研究三个新鉴定的Olig2靶点的调节表达，并确定这些基因如何控制MN分化的不同方面。首先，我们将确定Hes基因在控制前神经bHLH蛋白Neurogenin 2的表达和MN祖细胞分化的总体能力中的作用。其次，我们将研究Id基因在抑制Olig2和Ngn 2控制MN分化时间的功能中所起的作用。第三，我们将测试PLZF在维持脊髓祖细胞处于未分化状态中的作用，PLZF是一种控制其他组织中干细胞自我更新的转录因子。总之，这些研究将为干细胞和祖细胞如何在CNS中专门生成特定细胞类型提供重要的见解，并详细了解细胞分裂和分化过程是如何控制的。深入了解这一过程对于我们了解神经系统中不同细胞类型最初是如何形成的非常重要，对于目前和未来开发干细胞疗法以修复受伤或患病的神经组织至关重要。

DESCRIPTION (provided by applicant): The formation of neural circuits in the central nervous system (CNS) depends on the ability of undifferentiated stem and progenitor cells to produce distinct classes of neurons and glial cells in a stereotyped manner. Our main objective is to understand the molecular details of how general aspects of cell cycle regulation and differentiation are coordinated with cell fate decisions. Previously, we identified a bHLH class transcriptional represser called Olig2 that is selectively expressed by motor neuron (MN) progenitors in the spinal cord, and involved in coordinating three key features of MN development: MN- specific gene expression, cell cycle exit, and general neuronal differentiation. Since Olig2 functions as a represser, we hypothesize that Olig2 must direct MN formation through its ability to shut off the expression of other important regulatory genes that themselves control the fate, proliferation, and differentiation of stem and progenitor cells in the CNS. The identity of these genes is currently not known. Using in vitro and in vivo assays of gene function in chick and mouse spinal cord, we will examine the regulated expression of three newly identified Olig2 targets and determine how these genes control different aspects of MN differentiation. First, we will determine the role of Hes genes in controlling the expression of the proneural bHLH protein Neurogenin2 and the overall capacity of MN progenitors to differentiate. Second, we will examine the role that Id genes play in inhibiting the function of Olig2 and Ngn2 to control the timing of MN differentiation. Third, we will test the role of PLZF, a transcription factor that controls stem cell self-renewal in other tissues, in maintaining spinal cord progenitors in an undifferentiated state. Together, these studies will provide significant insight into how stem and progenitor cells become specialized to generate specific cell types in the CNS, and provide a detailed understanding of how the processes of cellular division and differentiation are controlled. Insights into this process are important for our understanding of how different cell types in the nervous system are initially formed, and critical for current and future efforts to develop stem cell therapies to repair injured or diseased neural tissue.