Role of the Foxn4 Gene during Retinogenesis

描述(申请人提供)：这项建议的长期目标是了解在哺乳动物视网膜发生过程中导致不同类型细胞的命运、承诺和分化的分子事件。无长突细胞和水平细胞是调节和整合视网膜回路中视觉信号的两类重要中间神经元。然而，尽管它们具有生理意义，但目前对它们发育的分子基础仍然知之甚少。在这一应用中，建议进行的实验将集中在FOXN4上，FOXN4是一种叉头/有翼螺旋转录因子，在分裂中的视网膜前体细胞子集中表达，该子集的特征是命运偏向于无长突细胞和水平细胞。根据我们的初步研究，推测Fonx4可能在这两种细胞的能力获得和命运承诺中发挥关键作用。 本提案中概述的研究旨在提供一种综合方法，以全面了解FOXN4在视网膜形成过程中的生物学功能。将追求四个具体目标：i)通过在祖细胞中过表达来研究FOXN4在视网膜发育过程中的作用。这些研究旨在利用逆转录病毒介导的FOXN4在小鼠视网膜中过表达的功能获得法来探讨FOXN4在哺乳动物视网膜发生中的作用；ii)通过靶向基因干扰来研究FOXN4在视网膜发育过程中的生物学功能。本实验旨在利用FOXN4基因敲除小鼠的产生和特征的功能丧失方法来揭示FOXN4在视网膜形成中的作用；iii)分析FOXN4和其他调节无长突细胞和水平细胞发育的视网膜生成因子之间的关系。这些研究旨在验证以下假设：FOXN4单独或与冗余因子结合，可能通过激活与这两种细胞类型相关的视网膜生成因子的表达来控制无长突细胞和水平细胞的发生；以及iv)绘制表达FOXN4的视网膜前体细胞的命运图。我们的目标是使用Cre-loxP命运映射策略来测试一种假设，即表达FOXN4的视网膜前体细胞的子集可能代表那些命运偏向于无长突细胞和水平细胞的细胞。 综上所述，这些拟议的研究有望为控制不同类型视网膜细胞发育的基因调控网络提供重要的新见解，并可能为更好地理解和治疗神经视网膜疾病提供基础。

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to understand the molecular events that lead to fate commitment and differentiation of different cell types during mammalian retinogenesis. The amacrine and horizontal cells are two classes of important interneurons that modulate and integrate visual signals in the retinal circuitry. Despite their physiological significance, however, the molecular bases underlying their development remain poorly understood at present. In this application, experiments are proposed that will focus on Foxn4, a forkhead/winged helix transcription factor that is expressed in a subset of dividing retinal progenitor cells characteristic of the subset with a fate biased toward amacrine and horizontal cells. Based on our preliminary studies it has been speculated that Fonx4 may play a key role in competence acquisition and fate commitment of these two cell types. The studies outlined in this proposal are designed to provide an integrated approach toward a comprehensive understanding of the biological function of Foxn4 during retinogenesis. Four specific aims will be pursued: i) to investigate the role of Foxn4 during retinal development by overexpression in progenitor cells. These studies aim to explore the function of Foxn4 during mammalian retinogenesis using a gain-of-function approach involving retrovirus-mediated overexpression of Foxn4 in the mouse retina; ii) to study the biological function of Foxn4 during retinal development by targeted gene disruption. The proposed experiments aim to uncover the role of Foxn4 during retinogenesis using a loss-of-function approach involving the production and characterization of Foxn4 knockout mice; iii) to analyze the relationship between Foxn4 and other retinogenic factors mediating amacrine and horizontal cell development. These studies aim to test the hypothesis that Foxn4 alone or in combination with a redundant factor, may control the genesis of amacrine and horizontal cells by activating the expression of retinogenic factors involved in the specification of these two cell types; and iv) to map the fate of Foxn4-expressing retinal progenitors. The goal is to use the Cre-loxP fate-mapping strategy to test the hypothesis that the subset of Foxn4-expressing retinal progenitors may represent those with a fate biased toward amacrine and horizontal cells. Taken together, these proposed studies are expected to provide important novel insights into the genetic regulatory networks that govern the development of different retinal cell types and may provide the foundation for better understanding and treatment of neuroretinal diseases.