Interaction of Isl1 and Pou4f2 in retinal development

描述（由申请人提供）：中枢神经系统（CNS）由不同的神经细胞类型组成。CNS发育中的一个常见范例是神经上皮中神经祖细胞的单个池产生不同的神经细胞类型。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。我们使用小鼠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。本研究的重点是视网膜神经节细胞的命运特化和分化.与其他视网膜细胞类型一样，RGC的发育起始于天然多能视网膜祖细胞（RPC），以逐步的方式进行，并受分层基因调控网络（GRN）的调控。在这个GRN中，三个转录因子Math 5、Isl 1和Pou 4f 2在RGC发育的两个不同阶段占据关键节点位置。Math 5在上游，是RPC获得RGC命运的能力所必需的，而Isl 1和Pou 4f 2在下游，协同作用以启动和维持RGC分化中的基因表达程序。然而，RGC命运的遗传和分子基础的规格，RGC发展的一个关键方面，仍然未知。本拨款提案侧重于Isl 1和Pou 4f 2在这一过程中的作用。我们的中心假设是，Isl 1和Pou 4f 2相互作用，并参与RGC的命运规范和分化。这一假设是基于我们目前对RGC发育缺陷的了解，以及相应的基因表达改变，在各自的敲除小鼠中。我们提出的实验将从几个不同的方面直接验证这一假设。我们提出的具体目标包括：1）检查Isl 1和/或Pou 4f 2是否可以在缺少Math 5的情况下指定RGC的命运; 2）研究Isl 1/Pou 4f 2协同调节下游基因的分子基础; 3）通过ChIP-seq定位发育中RGC基因组中Isl 1和Pou 4f 2的结合位点。总的来说，这些实验将为调节RGC形成的遗传途径提供重要的新见解。通过了解RGC如何形成和维持，我们还将获得关于它们在某些疾病条件下死亡的原因的有价值的信息，例如青光眼，视神经炎和缺血性视神经病变，从而能够为这些疾病开发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.