Regulation of Eye Growth and Development by the Lens

描述(申请人提供)：眼睛不同部分的发育和生长必须完美协调，才能将正确的视觉图像传输到大脑。晶状体在一定程度上负责协调眼睛的生长，但我们对其潜在机制的了解还不完全。这个问题将在墨西哥硬骨鱼中进行研究，这是一种硬骨鱼，由有眼的表层栖息型(表层鱼)和盲穴居型(穴居鱼)组成。眼原基最初是在洞鱼发育过程中形成的，但随后它们会停滞和退化，导致成年失明。首先退化的组织是晶状体，然后是视网膜。将正常的表层鱼胚胎晶状体移植到洞穴鱼的视杯中，可以恢复成年洞穴鱼的完整眼睛。一些基因，包括编码抗凋亡蛋白1A-晶体蛋白、热休克蛋白Hsp901和中线信号分子sonic hedgehog(Shh)的基因，都是洞鱼晶状体凋亡的候选调控基因。晶状体在保护视网膜免受细胞凋亡以及角膜和巩膜的正常发育方面也很重要。这个项目的总体目标是确定晶状体如何通过细胞凋亡而变得功能失调，以及异常晶状体如何反过来影响眼睛的整体生长和发育。前两个目标集中在导致晶状体内细胞凋亡的事件上。第一个目的是研究晶状体细胞凋亡中1A-晶状体蛋白和1B-晶状体蛋白下调的作用。第二个目的是研究hsp901上调在晶状体细胞凋亡中的作用，以及它是否存在于与shh和1-crystallin基因相关的可能的凋亡途径中。后两个目标移到晶状体外，聚焦于视网膜、角膜和巩膜，它们的发育依赖于晶状体，以及视网膜色素上皮(RPE)，它通常与晶状体合作，保护视网膜免受细胞凋亡的影响。第三个目的是研究视网膜基因，这些基因可能涉及控制视网膜生死的途径，以及晶状体在负责角膜和巩膜发育的迁移神经脊细胞的分化和图案形成中所起的作用。最终的目标将决定RPE是否与晶状体合作调节视网膜细胞的存活。这项应用的目的将结合晶状体显微外科操作、使用细胞和分子标记、实验基因过度表达和抑制以及遗传分析来创造缺乏特定视觉成分的鱼类品系，这些品系可用于检验眼睛生长协调的假说。这项研究旨在为晶状体如何协调眼睛生长以及这一过程中的缺陷如何导致失明提供新的见解。这将填补我们对正常和异常眼睛发育的理解上的一个主要空白。与公共健康相关：需要精确协调眼睛不同部位的发育，才能将正确的图像传输到大脑。以盲穴鱼为模型，本研究旨在提供有关人工晶状体在协调眼睛发育中的作用的新信息。这一结果将为研究眼睛发育异常提供依据。

DESCRIPTION (provided by applicant): Development and growth of the diverse parts of the eye must be perfectly coordinated in order to transmit correct visual images to the brain. The lens is responsible in part for coordinating eye growth but our knowledge about the underlying mechanisms is incomplete. This problem will be studied in Astyanax mexicanus, a teleost fish consisting of an eyed surface dwelling form (surface fish) and a blind cave-dwelling form (cavefish). Eye primordia are initially formed during cavefish development but they subsequently arrest and degenerate, resulting in a blind adult. The first tissue to degenerate is the lens, which is followed by the retina. Transplantation of a normal surface fish embryonic lens into a cavefish optic cup can restore a complete eye in adult cavefish. Several genes, including those encoding the anti-apoptotic protein 1A-crystallin, the heat shock protein Hsp901, and the midline signaling morphogen sonic hedgehog (shh) are candidates for regulators of cavefish lens apoptosis. The lens is also important in protecting the retina from apoptotic cell death and in the normal development of the cornea and sclera. The overall goal of this project is to determine how a lens becomes dysfunctional through apoptosis and how an abnormal lens in turn affects overall growth and development of the eye. The first two aims focus on events leading to apoptosis within the lens. The first aim will investigate the role 1A-crystallin and 1B-crystallin downregulation in lens apoptosis. The second aim will examine the role of hsp901 upregulation in lens apoptosis and its existence in a putative apoptotic pathway with shh and 1 -crystallin genes. The last two aims move outside the lens to focus on the retina, cornea and sclera, optic components whose development is dependent on the lens, and the retinal pigment epithelium (RPE), which may normally cooperate with the lens to protect the retina from apoptosis. The third aim investigates retinal genes that are potentially involved in the pathway controlling life or death of the retina, and the role of the lens in the differentiation and patterning of migratory neural crest cells responsible for cornea and sclera development. The final aim will determine if the RPE collaborates with the lens in mediating retinal cell survival. The aims of this application will combine lens microsurgical manipulations, the use of cellular and molecular markers, experimental gene overexpression and inhibition, and genetic analysis to create fish strains deficient in specific optic components that can be used to test hypothesis of eye growth coordination. This research is designed to provide new insights into how the lens coordinates eye growth and how blindness can result from defects in this process. This will fill a major gap in our understanding of both normal and abnormal eye development. PUBLIC HEALTH RELEVANCE: Precise developmental coordination of the different parts of the eye is required to transmit a correct image to the brain. Using the blind cavefish as a model, this study is designed to provide new information about the role of the ocular lens in coordinating eye development. The results will provide insights into abnormal eye development.