Regulatory mechanisms for retinal ganglion cell genesis

项目总结/摘要 了解各种神经元是如何从神经祖细胞分化出来的， 包括视网膜在内的中枢神经系统的生物学和疾病。所有视网膜细胞类型，包括 七种类型的神经元和Müller神经胶质细胞，来自视网膜祖细胞（RPC）， 发展任何视网膜细胞类型的缺陷都可能导致视力丧失甚至失明。中 视网膜神经节细胞（RGC）是视网膜神经元的唯一输出细胞，它将轴突发送到视网膜神经元。 视网膜受体以视神经的形式作用于大脑的靶区域。我们的长期目标是获得 全面了解调节RGC形成的遗传和分子机制， 发展三种转录因子作为RGC分化的关键调节因子; ATOH 7功能 上游使RPC能够胜任RGC谱系，而POU 4F 2和ISL 1的下游功能是 促进RGC分化。在上一个融资周期中，我们首次确定POU 4F 2和ISL 1 足以说明RGC的命运，并促进其分化，进一步澄清和建立 这两个因素在RGC发生中起着关键作用。尽管我们和其他人已经取得了进展，少校 我们对研资局发展的理解仍有疑问。具体来说，目前还不清楚是什么使 表达ATOH 7的RPC是独特的，因此RGC是从它们产生的，RGC特异性基因是如何激活的， ATOH 7在这些过程中发挥的特定作用，以及RGC前体一旦决定了它们的命运， 分化为成熟和功能性RGC。在本提案中，我们旨在解决这些重要问题。我们 最重要的假设是，表观遗传景观的变化是导致遗传变异的主要机制。 RGC发生的不同阶段的进展。因此，调查表观遗传景观 在RGC形成过程中影响基因表达的进化将是本提案的中心主题。我们 具体目标包括：1）研究研资局的性质; 通过克隆谱系分析、表达谱分析和表观基因组学调查， 通过RGC分化的表观遗传景观的进展，并确定RGC特异性增强子， 基因组;和3）实验评估和表征RGC特异性增强子的功能。总的来说， 这些目标是研究RGC形成的遗传和表观遗传基础。预期结果将 扩大我们的知识，从视网膜色素上皮细胞到视网膜神经节细胞的过渡过程中的分子事件， 发展它们还将帮助我们确定将干细胞重编程为RGC的要求， 这与开发RGC相关疾病的治疗方法高度相关。因此，我们提出的研究是有意义的， 既推进视网膜发育的基础研究，又为临床应用提供知识。

Project Summary/Abstract Understanding how the various neurons differentiate from neural progenitor cells is essential for understanding both the biology and diseases of the central nervous system, including the retina. All retinal cell types, including the seven types of neurons and the Müller glial cells, arise from retinal progenitor cells (RPCs) during development. Defects in any of the retinal cell types can cause vision loss and even blindness. Among the various retinal cells, retinal ganglion cells (RGCs) are the only output neurons, which send axons to the retinorecipient target regions of the brain in the form of the optic nerve. Our long-term goal is to obtain a comprehensive understanding of the genetic and molecular mechanisms regulating RGC formation during development. Three transcription factors serve as key regulators in RGC differentiation; ATOH7 functions upstream to render RPCs competent for the RGC lineage, whereas POU4F2 and ISL1 function downstream to promote RGC differentiation. In the last funding cycle, we for the first time established that POU4F2 and ISL1 are sufficient to specify the RGC fate and promote their differentiation, further clarifying and establishing the critical roles these two factors play in RGC genesis. Despite the progress we and others have made, major questions remain in our understanding of RGC development. Specifically, it remains unclear what makes ATOH7-expressing RPCs unique so that RGCs arise from them, how RGC-specific genes are activated, what specific roles ATOH7 plays in these processes, and how RGC precursors, once committed to their fate, further differentiate into mature and functional RGCs. In this proposal, we aim to address these important issues. Our overarching hypothesis is that changes in the epigenetic landscape are the major mechanism underlying the progression of RGC genesis through the different phases. Thus, investigating how the epigenetic landscape evolves to influence gene expression during RGC formation will be the central theme of this proposal. Our specific aims, which are all designed around, this theme, include: 1) to investigate the properties of RGC- competent RPCs by clonal lineage analysis, expression profiling, and epigenomics survey; 2) to survey the progression of the epigenetic landscape through RGC differentiation and identify RGC-specific enhancers in the genome; and 3) to experimentally evaluate and characterize the function of RGC-specific enhancers. Collectively, these aims address the genetic and epigenetic basis underlying RGC formation. The expected results will expand our knowledge about the molecular events during the transition from RPCs to RGCs in retinal development. They will also help us to define the requirement for reprograming stem cells into RGCs, which is highly pertinent to developing treatment for RGC-related diseases. Thus, our proposed research is significant in both advancing basic research on retinal development and providing knowledge for clinical applications.