Hedgehog Signaling and Cilia in Choroid Fissure Morphogenesis and Coloboma

脉络膜裂形态发生和缺损中的刺猬信号和纤毛

基本信息

批准号：
8864926
负责人：
Kristen M Kwan
金额：
$ 33.53万
依托单位：
UNIVERSITY OF UTAH
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-04-01 至 2020-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8864926
关键词：
Accounting Affect Architecture Automobile Driving Basal Cell Nevus Syndrome Biological Models Blindness Cell Death Cells Cessation of life Choroid Cilia Cleaved cell Coloboma Complex Computational Technique Computing Methodologies Data Defect Development Embryo Equilibrium Erinaceidae Etiology Event Excision Eye Four-dimensional Fresh Water Gene Activation Genes Genetic Goals Human Image Imaging Techniques Joubert syndrome Kidney Lead Life Live Birth Maps Microscopy Modeling Molecular Molecular Genetics Morphogenesis Movement Mutation Newborn Infant Optics Pathway interactions Penetrance Phenotype Process Regulation Reporter Role Signal Transduction Structure Syndrome Testing Time Tissues Vision Disorders Visual impairment Work Zebrafish base cell behavior cell motility ciliopathy imaging modality in vivo innovation molecular dynamics mutant novel novel strategies optic cup optic stalk public health relevance research study retinal axon smoothened signaling pathway teleost fish zebrafish development

项目摘要

DESCRIPTION (provided by applicant): Uveal coloboma, a condition estimated to occur in ~1:10,000 live births, is a significant cause of blindness worldwide. It is characterized by a hole or cleft in the eye, and results from defective formation or closure of the choroid fissure, a transient yet critical structure through which retinal axons exit and vasculature enters the eye. The Hedgehog (Hh) signaling pathway is vital for choroid fissure development: mutations upstream, downstream, and within the pathway can result in coloboma. Somewhat paradoxically, mutations that hyperactivate Hh signaling, as well as mutations that inactivate downstream targets, both lead to coloboma in humans, yet the specific morphogenetic defects underlying each of these models are unknown. In addition, primary cilia are required for vertebrate Hh signaling. Colobomata are associated with human ciliopathies, yet it is unclear whether the ciliopathy mutations activate or inactive Hh signaling in the eye, or how they disrupt specific morphogenetic processes to cause coloboma. Zebrafish presents an ideal model system to study this process: optical transparency and rapid development offer a unique opportunity to directly watch the choroid fissure form in vivo. We previously developed imaging and computational techniques to track and visualize cell movements throughout optic cup morphogenesis. However, choroid fissure development and the specific mechanisms disrupted in coloboma remain a mystery. In this proposal, we will determine the mechanisms underlying choroid fissure formation under normal conditions and in Hedgehog-driven zebrafish models of coloboma. I hypothesize that hyperactive Hedgehog signaling, acting through cilia, and loss of downstream effectors both result in coloboma by disrupting, in an opposing manner, cell movements underlying choroid fissure formation. Combining molecular genetics with innovative 4-dimensional live imaging and computational methods, we will test this hypothesis in the following specific aims: (1) determine how hyperactive Hh signaling, as caused by mutation in ptch2, disrupts choroid fissure formation; (2) determine how loss of the Hh downstream effector pax2 disrupts choroid fissure development to cause coloboma; and (3) determine the role of cilia signaling in choroid fissure development and ciliopathy-associated coloboma. The mechanistic experiments proposed here will define the cellular dynamics underlying normal choroid fissure formation, and the specific defects underlying three models of human coloboma, all of which affect the Hedgehog pathway: Gorlin syndrome, renal coloboma syndrome, and Joubert/COACH syndrome. Our work represents a novel strategy to understand the etiology of this potentially devastating vision disorder.

描述（由申请人提供）：葡萄膜缺损是一种估计约 1:10,000 活产儿中发生的疾病，是全世界失明的一个重要原因，其特点是有一个洞。脉络膜裂是一种短暂但关键的结构，视网膜轴突通过该结构退出，脉管系统进入眼睛。刺猬 (Hh) 信号通路对于脉络膜裂的发展至关重要：上游突变。有点矛盾的是，Hh 信号传导过度激活的突变以及下游靶点失活的突变都会导致缺损。人类纤毛缺陷，但这些模型背后的具体形态发育缺陷尚不清楚。此外，脊椎动物 Hh 信号传导需要初级纤毛，但纤毛病突变是否激活或失活 Hh 信号传导尚不清楚。斑马鱼的眼睛，或者它们如何破坏特定的形态发生过程而导致缺损，为研究这一过程提供了一个理想的模型系统：光学透明度和快速发育提供了直接观察斑马鱼的独特机会。我们之前开发了成像和计算技术来跟踪和可视化整个视杯形态发生的细胞运动，但是，脉络膜裂的发育和缺损中破坏的具体机制仍然是一个谜。在正常条件下和刺猬驱动的斑马鱼缺损模型中，脉络膜裂的形成我认为通过纤毛起作用的过度活跃的刺猬信号和下游效应器的损失都会导致这种情况。缺损通过以相反的方式破坏脉络膜裂形成的细胞运动将分子遗传学与创新的 4 维实时成像和计算方法相结合，我们将在以下具体目标中检验这一假设：（1）确定 Hh 信号传导如何过度活跃。由 ptch2 突变引起，扰乱脉络膜裂形成；(2) 确定 Hh 下游效应器 pax2 的缺失如何扰乱脉络膜裂发展而导致缺损；确定纤毛信号在脉络膜裂发育和纤毛病相关缺损中的作用这里提出的机制实验将定义正常脉络裂形成的细胞动力学，以及三种人类缺损模型的具体缺陷，所有这些都会影响 Hedgehog 通路。：Gorlin 综合征、肾缺损综合征和 Joubert/COACH 综合征是一种了解这种潜在破坏性视力障碍病因的新策略。