Molecular Genetic Analysis of Sclera Development and Degeneration

 描述(申请人提供)：巩膜是包裹在眼球周围的纤维弹性涂层，提供结构支撑和灵活性，对将图像聚焦到视网膜至关重要。尽管它在视觉发育和疾病中很重要，但巩膜发育和退化的分子机制却知之甚少。该提案将利用研究墨西哥硬骨鱼巩膜发育和退化的新机会来填补这一空白，该硬骨鱼是一种由有眼表层鱼(表层鱼)和盲洞(洞穴鱼)组成的单一物种。在这个物种中，眼睛组织处理方法、基因组工具，以及--最重要的--强大的遗传方法的存在，都是可用的。眼原基最初在洞鱼中形成，但随后停滞和退化。首先退化的洞鱼组织是晶状体，随后会影响包括巩膜在内的其他视觉组织的发育。将表面鱼胚胎晶状体移植到洞穴鱼视杯中，可以恢复正常的巩膜表型，表明晶状体在巩膜发育中起作用。其他眼组织，即视网膜色素上皮(RPE)和颅神经脊(Cnc)，也可能控制巩膜发育的各个方面。本项目的总体目标是确定巩膜发育和退变的分子机制。第一个具体目标是调查晶状体、RPE和CnC作为巩膜发育的组织者所扮演的角色。这一目标将使用物理和遗传操作的组合来揭示这些眼睛组织在组织发育中的巩膜方面的贡献。第二个特定目标将确定在晶状体、RPE、CNC和/或巩膜本身中表达的调节正常和异常巩膜发育的基因。这些基因将被筛选为特定的基因，并通过定位到一组导致异常巩膜表型的特定基因组区域(QTL)来减少到可管理的数量。第三个具体目标将通过控制与巩膜相关的基因在表层鱼类和穴居鱼中的表达并确定对巩膜发育的影响来确定巩膜相关基因的功能。第四个具体目标是确定导致巩膜缺陷的基因突变。这项研究旨在通过对巩膜发育的影响来揭示导致视力衰退的机制、基因和突变。

 DESCRIPTION (provided by applicant): The sclera is the fibrous elastic coat surrounding the eyeball that provides the structural support and flexibility critical for focusing an image on the retina. Despite its importance in optic development and disease, the molecular mechanisms of sclera development and degeneration are poorly understood. This proposal will fill this gap by capitalizing on novel opportunities for studying sclera development and degeneration in the teleost Astyanax mexicanus, a single species consisting of eyed surface (surface fish) and blind cave (cavefish) forms. In this species, eye tissue manipulation methods, genomic tools, and - most importantly - the existence of a powerful genetic approach, are available. Eye primordia are initially formed in cavefish but subsequently arrest and degenerate. The first cavefish tissue to degenerate is the lens, which subsequently affects development of other optic tissues including the sclera. Transplantation of a surface fish embryonic lens into a cavefish optic cup restores the normal sclera phenotype, showing that the lens functions in sclera development. Other eye tissues, namely the retinal pigment epithelium (RPE) and cranial neural crest (CNC), may also control aspects of sclera development. The overall goal of this project is to determine the molecular mechanisms of sclera development and degeneration. The first specific aim is to investigate the roles of the lens, RPE, and CNC as organizers of sclera development. This aim will use a combination of physical and genetic manipulations to reveal the contributions of these eye tissues in organizing the developing sclera. The second specific aim will identify the genes expressed in the lens, RPE, CNC, and/or the sclera itself that mediate normal and abnormal sclera development. These genes will be filtered for specifically and reduced to a manageable number by mapping to a set of specific genomic regions (QTL) responsible for the abnormal sclera phenotype. The third specific aim will determine the function of the sclera related genes by manipulating their expression in surface fish and cavefish and determining the effects on sclera development. The fourth specific aim will identify the mutations in genes responsible for sclera defects. This study is designed to reveal the mechanisms, genes, and mutations responsible for visual decay through effects on development of the sclera.