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）中神经回路的形成依赖于未分化的干细胞和祖细胞以刻板的方式产生不同类别的神经元和胶质细胞的能力。我们的主要目标是了解细胞周期调节和分化的一般方面如何与细胞命运决定协调的分子细节。在此之前，我们发现了一种名为Olig2的bHLH类转录抑制因子，它在脊髓中的运动神经元（MN）祖细胞中选择性表达，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具有抑制作用，我们假设Olig2必须通过其关闭其他重要调控基因的表达的能力来指导MN的形成，这些基因本身控制着中枢神经系统中干细胞和祖细胞的命运、增殖和分化。这些基因的身份目前尚不清楚。通过鸡和小鼠脊髓的体外和体内基因功能分析，我们将研究三个新发现的Olig2靶点的调控表达，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基因在控制前体细胞bHLH蛋白Neurogenin2表达和MN祖细胞总体分化能力中的作用。其次，我们将研究Id基因在抑制Olig2和Ngn2控制MN分化时间的功能中所起的作用。第三，我们将测试PLZF（一种控制其他组织中干细胞自我更新的转录因子）在维持脊髓祖细胞处于未分化状态中的作用。总之，这些研究将为干细胞和祖细胞如何在中枢神经系统中特化产生特定的细胞类型提供重要的见解，并提供细胞分裂和分化过程如何被控制的详细理解。深入了解这一过程对于我们理解神经系统中不同类型的细胞最初是如何形成的非常重要，对于当前和未来开发干细胞疗法来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.