Transcriptional Regulation of Cone Photoreceptor Genesis

描述（由申请人提供）：视锥细胞光感受器（视锥细胞）在人类视觉中起着关键作用，如果这些细胞死亡，则会发生视觉上的严重损伤。例如，色素性视网膜炎和黄斑变性是两种这样的疾病，其中视觉的实质性丧失与视锥细胞的丧失相关。治疗这些疾病的一种有希望的疗法是用患者体内或体外产生的新视锥细胞替换丢失的视锥细胞。然而，脊椎动物视锥细胞发生的基本分子机制仍不清楚。如果没有这些信息，就不可能有一个合理的策略来生产圆锥。长期目标是确定促进视锥细胞发生的基因调控网络，并根据这些知识设计方法来制造用于细胞替代疗法的新视锥细胞。这项提议的总体目标是从功能上剖析转录网络， 允许视网膜祖细胞的特定亚群优先产生两种罕见的视网膜细胞类型，视锥细胞和水平细胞。这一提议将检验中心假设， 转录因子Otx 2和Onecut 1是这种特异性锥/水平细胞祖细胞的主要调节因子。进行这项研究的基本原理是，通过了解促进这些祖细胞和最终的视锥光感受器细胞的形成的转录因子网络，在体外或体内产生新的视锥光感受器的方法将成为可能。为了验证这一假设，提出了两个具体的目标：1）鉴定建立视锥/水平祖细胞状态并促进视锥发生的转录因子，以及2）定义Onecut1和Otx 2表达的关键参数，所述Onecut1和Otx 2表达诱导视锥/水平祖细胞并从其他视网膜祖细胞类型分化视锥。第一个目标将确定在锥体/水平祖细胞中特异性表达的基因以及Onecut1和Otx2转录因子产生这种分子特征的程度。此外，它将确定Onecut1下游抑制视杆细胞发生的转录因子途径。第二个目标将测试Onecut1和Otx2可以在多大程度上将其他视网膜祖细胞重新编程为产生视锥细胞和水平细胞的特定类型，并最终驱动视锥细胞分化程序，同时抑制视杆细胞的发生。这种方法是创新的，因为它将在整个转录组水平上功能性地研究视网膜祖细胞的特定亚群。此外，还将对参与球果发生的最上游转录因子网络进行剖析和探索。在这个项目完成后，新的途径将可用于了解特定视网膜祖细胞类型的生物学，以及锥和杆感光细胞发育的早期步骤。这里提出的研究是重要的，因为它有望揭示新的，基本的见解锥光感受器的起源。预计这些知识将对人类失明的新疗法的开发具有转化潜力。

DESCRIPTION (provided by applicant): Cone photoreceptors (cones) serve a critical function in human vision that is underscored by the dramatic impairments in sight that occur if these cells die. For instance, retinitis pigmentosa and macular degeneration are two such diseases in which substantial loss of vision correlates with the loss of cones. One promising therapy for these diseases is to replace lost cones with new ones produced inside or outside of the patient. However, the fundamental molecular mechanisms underlying the genesis of vertebrate cones are still unclear. Without this information, a rational strategy to produce cones is unavailable. The long-term goal is to identify the gene regulatory networks that promote cone genesis, and to devise methods based on this knowledge to make new cone cells for cell replacement therapy. The overall objective of this proposal is to functionally dissect the transcriptional networks that allow a specific sub-population of retinal progenitor cells to preferentially generate two rare retinal cell types, cones and horizontal cells. This proposal will test the central hypothesis that the transcription factors Otx2 and Onecut1 are the master regulators of this specific cone/horizontal cell progenitor cell. The rationale for undertaking this study is that by understanding the transcription factor networks that promote the formation of these progenitor cells and ultimately cone photoreceptor cells, methods for generating new cone photoreceptors in vitro or in vivo will become possible. To test this hypothesis, two specific aims are proposed: 1) Identify the transcription factors that establish the cone/horizontal progenitor cell state and promote cone genesis and 2) Define critical parameters of Onecut1 and Otx2 expression that induce cone/horizontal progenitors and differentiated cones from other retinal progenitor cell types. The first aim will determine the genes expressed specifically in cone/horizontal progenitor cells and the extent to which this molecular signature is generated by the Onecut1 and Otx2 transcription factors. In addition, it will identify the transcription factor pathways downstream o Onecut1 that repress rod photoreceptor genesis. The second aim will test the extent to which Onecut1 and Otx2 can reprogram other retinal progenitors into the specific type that generates cones and horizontal cells and ultimately drive the cone differentiation program, while repressing rod genesis. This approach is innovative because it will functionally investigate a specific sub-population of retinal progenitor cells at the whole transcriptome level. In addition, t will dissect and explore the most upstream transcription factor network involved in cone genesis. At the completion of this project, new avenues will be available to understand the biology of specific retinal progenitor types, as well as the early steps in cone and rod photoreceptor development. The research proposed here is significant because it is expected to reveal novel, fundamental insights into the genesis of cone photoreceptors. It is expected that this knowledge will have translational potential for the development of new therapies for human blindness.