Role of Wnt/Frizzled signaling during eye development

描述(申请人提供)：在脊椎动物眼睛的发育过程中，会发生复杂的图案事件，导致产生不同的组织成分。多发性先天性眼病，包括无眼球或小眼球、无虹膜、缺损和视网膜发育不良，起源于早期眼睛发育中断。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，调节构图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者。WNTs通过与Frizzled型跨膜受体家族成员结合而发挥作用。然而，Wnt/Frizzled信号在脊椎动物眼睛发育中的作用尚未被研究，尽管多个Wnt和Frizzleds在眼睛发育的不同阶段都有表达。我们提供了Wnt/β-catenin信号在视泡中活跃的证据，并假设它调节视网膜前体细胞的增殖和RPE的发育。为了验证这一点，我们建议在小鼠、小鸡和非洲爪哇上进行实验，因为每个模型系统都提供了独特的实验优势。我们将在转基因非洲爪哇和小鼠胚胎中使用Wnt/β连环蛋白信号的报告来确定在眼睛发育过程中这一信号通路何时何地活跃(目标1)。然后，我们将测试Wnt/β-catenin信号是否通过在鸡和非洲爪哇眼睛发育的不同阶段干扰这一信号通路来调节祖细胞的增殖和RPE的发育(AIMS 2)。最后，我们将确定这些效应是否由Frizzled5受体介导，该受体选择性地在发育中的视泡中表达(目标3)。总而言之，这些实验将促进我们对发育过程中眼睛图案的信号的理解，并可能提供关于这些图案事件如何在先天性眼病中被破坏的线索。此外，这些研究应该为Wnt/β-catenin信号在神经系统发育中的作用提供更全面的见解。

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.