Role of Chx10 in embryonic Retinal Progenitor Cells

描述（由申请人提供）：含同源结构域的转录因子Chx 10是视网膜发育的中心调节因子。我们对Chx 10功能的了解大部分来自于使用眼发育迟缓J（或J）小鼠的研究，这些小鼠在Chx 10基因中具有无效突变。我们实验室的工作有助于了解其在视网膜祖细胞（RPC）增殖和细胞周期进程中的作用。此外，我们的工作和其他人揭示，Chx 10还影响神经发生的时间，维持神经视网膜的身份，调节成人视网膜干细胞，并为双极细胞形成所需。我们工作的主要目标是揭示驱动视网膜发育的特定Chx 10依赖性分子机制和途径。实现这一目标的一个挑战是RPC特性的多种改变（在orJ小鼠中评估）在时间上重叠并且在视网膜发育的早期开始。因此，尚不清楚这些变化是否由共享机制介导，以及Chx 10是否需要在发育后期调节RPC特性。为了解决这些问题，深入了解Chx 10功能的分子机制，我们提出了三个目标。在目标1中，我们将使用Chx 10和嵌合小鼠的条件等位基因进行一系列遗传实验，以确定RPC中需要Chx 10时的发育阶段，并确定Chx 10丢失诱导的RPC变化是否仅归因于细胞自主机制。在目标2和3中，我们研究了Chx 10功能的两种潜在机制。目标2建立在我们最近对hedgehog信号传导的研究基础上，表明Chx 10的缺失影响了对增殖重要的信号传导途径的效率。使用培养测定和基因表达测量，我们将研究Chx 10如何与刺猬途径相互作用。在目标3中，我们研究了Chx 10和含有同源结构域的转录因子Lhx 2（早期眼睛发育的重要调节因子）之间的潜在相互作用，使用遗传方法在小鼠中。我们的研究有可能为控制视网膜形成的复杂机制提供丰富的图谱，并可以为干细胞治疗视网膜疾病的精细应用提供见解。公共卫生相关性：小眼症是一种先天性异常，其中眼睛无法生长到正常大小。据报道，包括小眼症在内的眼部畸形高达1/5000，出生时患有这些畸形的儿童往往严重视力受损或失明。这里提出的研究目标是了解这些缺陷的基础，希望有一天能为这些毁灭性的残疾开发出恢复性治疗或治愈方法。

DESCRIPTION (provided by applicant): The homeodomain-containing transcription factor Chx10 is a central regulator of retinal development. Much of what we know about Chx10 function comes from studies using ocular retardation J (orJ) mice, which have a null mutation in the Chx10 gene. Work from our laboratory has contributed to an understanding of its role in retinal progenitor cell (RPC) proliferation and cell cycle progression. Additionally, our work and others reveal that Chx10 also influences the timing of neurogenesis, maintains neuroretinal identity, regulates adult retinal stem cells, and is required for bipolar cell formation. The primary goal of our work is to uncover the specific Chx10-dependent molecular mechanisms and pathways driving retinal development. One challenge in achieving this goal is that multiple alterations in RPC properties (assessed in orJ mice) overlap in time and initiate early in retinal development. Because of this, it is not known if these changes are mediated by shared mechanisms and whether Chx10 is required for regulating RPC properties at later stages of development. To resolve these issues and gain insight into molecular mechanisms of Chx10 function, we propose three aims. In Aim 1, we will perform a series of genetic experiments using a conditional allele of Chx10 and chimeric mice to determine developmental stages when Chx10 required in RPCs and to determine if RPC changes induced by Chx10 loss are due solely to cell-autonomous mechanisms. In Aims 2 and 3, we investigate two potential mechanisms of Chx10 function. Aim 2 builds on our recent study of hedgehog signaling indicating that loss of Chx10 influences the efficiency of signaling pathways important for proliferation. Using culture assays and gene expression measurements, we will investigate how Chx10 interacts with the hedgehog pathway. In Aim 3, we investigate a potential interaction between Chx10 and the homeodomain-containing transcription factor Lhx2 (an essential regulator of early eye development) using genetic approaches in mice. Our studies have the potential to provide a rich map of the complex mechanisms controlling formation of the retina and could provide insights into the refined use of stem cells for treating retinal disease. PUBLIC HEALTH RELEVANCE: Microphthalmia is a congenital anomaly in which the eye fails to grow to its normal size. Ocular malformations, which include microphthalmia are reported to be as high as 1 in 5000 births and children born with these malformations are often severely visually impaired or blind. The goals of the research proposed here are to understand the basis for these defects with the hope of one day developing a restorative treatment or cure for these devastating disabilities.