Interaction of Isl1 and Pou4f2 in retinal development

描述（由申请人提供）：中枢神经系统（CNS）由不同类型的神经细胞组成。中枢神经系统发育的一个常见范例是，神经上皮内的单一神经祖细胞池产生多种神经细胞类型。尽管取得了重大进展，但对中枢神经系统细胞多样性形成的遗传机制仍缺乏明确的认识。我们用老鼠的神经视网膜来解决这个问题。我们的长期目标是了解转录因子如何在全球范围内调节基因表达以协调各种视网膜细胞类型的形成。本文对视网膜神经节细胞（RGCs）的命运规范和分化进行了研究。与其他视网膜细胞类型一样，RGC的发育始于天然的多能性视网膜祖细胞（rpc），以逐步的方式发展，并受到分层基因调控网络（GRN）的调节。在这个GRN中，三个转录因子Math5、Isl1和Pou4f2占据了RGC发展的两个不同阶段的关键节点位置。Math5位于上游，是RPCs获得获得RGC命运的能力所必需的，而Isl1和Pou4f2位于下游，协同启动和维持RGC分化中的基因表达程序。然而，基因和分子的基础规范的研资局命运，一个关键方面的研资局发展，仍然是未知的。本拨款提案的重点是Isl1和Pou4f2在这一过程中的作用。我们的中心假设是Isl1和Pou4f2相互作用并参与RGC命运规范和分化。这一假设是基于我们目前对基因敲除小鼠中RGCs发育缺陷和相应基因表达改变的了解。我们提出的实验将从几个不同的方面直接检验这一假设。我们提出的具体目标包括：1)检查Isl1和/或Pou4f2是否可以在没有Math5的情况下指定RGC命运；2)研究Isl1/Pou4f2协同调控下游基因的分子基础；3)利用ChIP-seq技术定位发育中的RGCs基因组中Isl1和Pou4f2的结合位点。总的来说，这些实验将为调控RGC形成的遗传途径提供重要的新见解。通过了解RGCs是如何形成和维持的，我们也将获得有价值的信息，了解它们在某些疾病条件下死亡的原因，如青光眼、视神经炎和缺血性视神经病变，从而能够为这些疾病制定新的预防和治疗策略。

DESCRIPTION (provided by applicant): The central nervous system (CNS) is composed of diverse neural cell types. A common paradigm in the development of the CNS is that single pools of neural progenitor cells in the neural epithelium give rise to the diverse neural cell types. Despite significant progress, a clear understanding of the genetic mechanism underlying formation of the cellular diversity in the CNS is still lacking. We use the mouse neural retina to address this question. Our long-term goal is to understand how transcription factors regulate gene expression globally to orchestrate the formation of the various retinal cell types. This proposal focuses on the fate- specification and differentiation of retinal ganglion cells (RGCs). As with other retinal cell types, RGC development initiates from natve multipotent retinal progenitor cells (RPCs), progresses in a stepwise fashion, and is regulated by a hierarchical gene regulatory network (GRN). Within this GRN, three transcription factors, Math5, Isl1 and Pou4f2, occupy key node positions at two different stages of RGC development. Math5 is upstream and is required for RPCs to gain competence for an RGC fate, whereas Isl1 and Pou4f2 are downstream and function collaboratively to initiate and maintain the gene expression program in RGC differentiation. However, the genetic and molecular basis for the specification of the RGC fate, a key aspect of RGC development, remains unknown. This grant proposal focuses on the roles of Isl1 and Pou4f2 in this process. Our central hypothesis is that Isl1 and Pou4f2 interact with each other and participate in RGC fate-specification and differentiation. This hypothesis is based on our current knowledge of defective development of RGCs, and corresponding alterations in gene expression, in the respective knockout mice. The experiments we propose will directly test this hypothesis from several different aspects. The specific aims we propose include: 1) To examine whether Isl1 and/or Pou4f2 can specify RGC fate in the absence of Math5; 2) To investigate the molecular basis for the Isl1/Pou4f2 collaboration in regulating downstream genes; 3) To map the binding sites of Isl1 and Pou4f2 in the genome of developing RGCs by ChIP-seq. Collectively, these experiments will provide significant new insights into the genetic pathways regulating RGC formation. By learning how RGCs form and are maintained, we will also obtain valuable information on why they die under certain disease conditions, such as glaucoma, optic neuritis, and ischemic optic neuropathy, and thus be able to develop novel preventive and therapeutic strategies for these diseases. PUBLIC HEALTH RELEVANCE: Retinal ganglion cells are essential to human vision and damages to them are implicated in various eye diseases such as glaucoma, optic neuritis, and ischemic optic neuropathy. The objective of this proposal is to understand how retinal ganglion cells are generated and maintained by studying the functions of two genes, Isl1 and Pou4f2, required in these processes. The knowledge obtained from this study will serve as guidance in future endeavors of developing preventive and therapeutic measures for these diseases.