Role of Wnt/Frizzled signaling during eye development

描述（由申请人提供）：在脊椎动物眼睛的发育过程中，会发生复杂的图案化事件，导致不同组织成分的产生。多种先天性眼部疾病，包括无眼或小眼、无虹膜、缺损和视网膜发育不良，源于早期眼部发育的中断。因此，确定导致眼组织，特别是视网膜和视网膜色素上皮（RPE）的图案化和分化的机制是至关重要的。在大多数情况下，介导模式化事件的分子信号是未知的。wnt配体家族的成员是多种组织中细胞增殖、细胞命运决定和组织极性的重要调节剂。Wnt通过与跨膜受体的卷曲家族的成员结合而起作用。然而，Wnt/Frizzled信号在脊椎动物眼睛发育中的作用尚未被研究，尽管事实上多个Wnt和Frizzled在眼睛发育的各个阶段表达。我们提供的证据表明，Wnt/β-连环蛋白信号是活跃的视泡，并假设它调节视网膜祖细胞增殖和RPE的发展。为了测试这一点，我们提出了在小鼠，小鸡和爪蟾实验，因为每个模型系统提供了独特的实验优势。我们将在转基因非洲爪蟾和小鼠胚胎中使用Wnt/β-连环蛋白信号的报告基因来确定在眼睛发育过程中该信号通路何时何地是活跃的（目的1）。然后，我们将测试Wnt/β-连环蛋白信号传导是否通过在鸡和非洲爪蟾的眼睛发育的各个阶段扰乱该信号传导途径来调节祖细胞增殖和RPE发育（目的2）。最后，我们将确定这些影响是否介导的卷曲-5受体，这是选择性地表达在发展中的视泡（目的3）。总之，这些实验将促进我们对发育过程中眼睛图案信号的理解，并可能提供有关这些图案事件如何在先天性眼病中被破坏的线索。此外，这些研究应该提供更全面的了解Wnt/β-连环蛋白信号在神经系统发育过程中的作用。

DESCRIPTION (provided by applicant): During development of the vertebrate eye, complex patterning events occur which result in the generation of distinct tissue components. Multiple congenital eye disorders, including anophthalmia or micropthalmia, aniridia, coloboma and retinal dysplasia, stem from disruptions in early eye development. Thus, it is critical to define the mechanisms that lead to the patterning and differentiation of ocular tissues, in particular the retina and retinal pigment epithelium (RPE). The molecular signals that mediate patterning events are, for the most part, unknown. Members of the wnt family of ligands are important regulators of cellular proliferation, cell fate decisions and tissue polarity in multiple tissues. Wnts act by binding to members of the Frizzled family of transmembrane receptors. However, the role of Wnt/Frizzled signaling in vertebrate eye development has not been examined, despite the fact that multiple Wnts and Frizzleds are expressed at various stages of eye development. We provide evidence that Wnt/beta-catenin signaling is active in the optic vesicle and hypothesize that it regulates retinal progenitor proliferation and RPE development. To test this we propose experiments in mouse, chick and Xenopus, since each model system offers unique experimental advantages. We will use a reporter of Wnt/beta catenin signaling in transgenic Xenopus and mouse embryos to define when and where during eye development this signaling pathway is active (Aim 1). We will then test whether Wnt/beta-catenin signaling regulates progenitor proliferation and RPE development by perturbing this signaling pathway at various stages of eye development in both chick and Xenopus (Aims 2). Finally, we will determine whether these effects are mediated by the Frizzled-5 receptor, which is selectively expressed in the developing optic vesicle (Aim 3). Together, these experiments will advance our understanding of the signals that pattern the eye during development and may provide clues about how these patterning events are disrupted in congenital eye disorders. In addition, these studies should provide more general insight into the role of Wnt/beta-catenin signaling during nervous system development.