Mechanisms governing Nuclear Factor I gene induction and function during the ini

描述（由申请人提供）：神经胶质细胞约占成人中枢神经系统（CNS）细胞组成的90%，并支持CNS功能所必需的大量生理作用。然而，在体内控制多能神经干细胞胶质细胞生成的分子过程仍然知之甚少。因此，这项建议的首要目标是阐明从神经干细胞的胶质细胞发生的启动机制。我们最近证明，核因子I（NFI）基因控制神经胶质细胞在胚胎脊髓中的生成，并在神经干细胞群中诱导与胶质细胞在体内的发病。这些特性使得NFI基因成为研究诱导和维持胶质细胞生成早期阶段的基因调控程序的理想起点。因此，我们假设解剖与NFI基因调控相关的上游和下游事件将为胶质细胞生成的分子控制提供新的见解。 具体目标1和2的建议是基于我们的发现，两个不同的监管机构的NFI基因表达在胚胎脊髓。使用增强子筛选的NFIA启动子，我们已经确定了一个高度保守的增强子元件（e123），概括的空间和时间模式的NFIA诱导时，引入鸡胚脊髓。因此，在目标1中，我们建议利用e123作为一种工具，以确定一组核心的转录因子，控制NFIA诱导。我们还发现，骨形态发生蛋白（BMP）信号控制NFI基因在胚胎脊髓中的表达的方式是独立的e123增强子研究目的1。因此，在目标2中，我们计划确定BMP-响应元件的NFIA启动子，确定的具体作用，BMP信号在NFI基因表达的调节，并建立BMP信号确实独立的转录控制机制，调节e123诱导。最后，目的3是一个逻辑的延伸，在神经干细胞的基因表达的时间分析研究，我们确定了一个队列的基因上调后，NFI基因诱导胚胎脊髓。初步研究表明，这些基因中的四个足以在NFIA不存在的情况下恢复胶质细胞生成，这表明它们在NFI基因的下游起作用。我们将在体内使用获得和丧失功能的方法来发现这些基因是否以及如何促进胶质细胞生成和在胶质细胞生成的启动过程中NFI基因下游的功能。在完成这些研究后，我们希望有一个更全面的分子过程的地图，上游和下游的NFI基因控制中枢神经系统发育过程中胶质细胞生成的启动。由此产生的见解的信号，指定的承诺，胶质细胞谱系应解除了解神经胶质细胞规格在胚胎脊髓从投机领域的一点，临床应用可以开始被考虑。 公共卫生相关性：该项目的重点是控制神经胶质细胞生成的分子过程。神经胶质细胞与神经系统的大量癌症和退行性疾病有关，了解控制其生成的发育过程是开发这些疾病新治疗方法的关键。这个建议是围绕一个基因家族，控制神经胶质细胞的产生，也表达在星形细胞瘤，并有助于他们的形成。因此，本文的研究直接适用于星形细胞瘤的理解和治疗。

DESCRIPTION (provided by applicant): Glial cells comprise approximately 90% of the cellular constituency of the adult central nervous system (CNS) and support a vast array of physiological roles essential to CNS function. Yet, the molecular processes that control the initiation of gliogenesis from multipotent neural stem cells in vivo remain poorly understood. Thus, the overriding goal of this proposal is to elucidate the mechanisms that govern the initiation of gliogenesis from neural stem cells. We recently demonstrated that nuclear factor I (NFI) genes control the generation of glial cells in the embryonic spinal cord and are induced in neural stem cell populations coincident with the onset of gliogenesis in vivo. These properties make the NFI genes an ideal starting point from which to investigate the genetic regulatory programs that induce and maintain the early stages of gliogenesis. We, therefore, hypothesize that dissection of both the upstream and downstream events associated with NFI gene regulation will provide novel insights into the molecular control of gliogenesis. Specific Aims 1 and 2 of this proposal are based on our discovery of two distinct regulators of NFI gene expression in the embryonic spinal cord. Using enhancer screening of the NFIA promoter we have identified a highly conserved enhancer element (e123) that recapitulates the spatial and temporal patterns of NFIA induction when introduced into the embryonic chick spinal cord. Thus, in Aim 1 we propose to exploit e123 as a tool to identify a core set of transcription factors that control NFIA induction. We have also found that bone morphogenic protein (BMP) signaling controls NFI gene expression in the embryonic spinal cord in a manner that is independent of the e123 enhancer studied in Aim 1. Therefore, in Aim 2 we plan to identify BMP-responsive elements in the NFIA promoter, define the specific role of BMP signaling in the regulation of NFI gene expression, and to establish that BMP signaling does indeed operate independently of the transcriptional control mechanisms that regulate e123 induction. Finally, Aim 3 is a logical extension of temporal profiling studies of gene expression in neural stem cells in which we identified a cohort of genes upregulated after NFI gene induction in the embryonic spinal cord. Preliminary studies indicate that four of these genes are sufficient to restore gliogenesis in the absence of NFIA, suggesting that they function downstream of NFI genes. We will use gain- and loss-of function approaches in vivo to discover whether and how these genes promote gliogenesis and function downstream of NFI genes during the initiation of gliogenesis. Upon completion of these studies, we expect to have a much more comprehensive map of molecular processes, both upstream and downstream of NFI genes that control the initiation of gliogenesis during CNS development. The resultant insights into the signals that specify commitment to the glial lineage should lift understanding of glial cell specification in the embryonic spinal cord from the speculative realm to a point where clinical applications can begin to be considered. PUBLIC HEALTH RELEVANCE: This project focuses on the molecular processes that control the generation of glial cells. Glial cells have been implicated in a vast array of cancers and degenerative diseases of the nervous system and understanding the developmental processes that control their generation is a key to developing new therapeutic approaches to these disorders. This proposal is centered around a gene family that controls the generation of glial cells and is also expressed in astrocytomas and contributes to their formation. Thus, the studies herein are directly applicable to the understanding and treatment of astrocytomas.