Retinoid Dehydrogenases Involved in Eye Development

类视黄醇脱氢酶参与眼睛发育

• 批准号: 6622890
• 负责人: GREGG L DUESTER
• 金额: $ 44.55万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6622890
• 关键词: aldehyde dehydrogenases; biological signal transduction; cell differentiation; congenital eye disorder; developmental genetics; enzyme activity; enzyme mechanism; eye; gene expression; gene targeting; genetically modified animals; histology; in situ hybridization; laboratory mouse; mutant; neurogenesis; neuronal guidance; neurons; nutrition related tag; retina; retinoate; retinoids; vitamin A deficiency; vitamin metabolism

Retinoic acid (RA), a metabolic derivative of vitamin A (retinol), is essential for axial patterning of the eye during vertebrate development. Retinoid signaling occurs when retinol is metabolized to retinal and then to RA which serves as a ligand for nuclear retinoid receptors that regulate gene expression. Disruption of retinoid signaling either by gestational vitamin A deficiency or by creation of retinoid receptor null mutations results in abnormal dorsoventral axial development of the eye. The mechanism for generation of RA locally in the eye as well as the mechanism for how RA regulates dorsoventral patterning of the eye are not yet understood. Our understanding of how retinol is physiologically activated to form RA is still vague, but has been improved by discovery of three retinoid dehydrogenases expressed in the eye that metabolize retinal to RA, i.e. RALDH1, RALDH2, and RALDH3, all members of the aldehyde dehydrogenase (ALDH) enzyme family. Raldh2 null mutant mice generated in this laboratory and another have revealed phenotypes that are lethal at midgestation with massive trunk and forelimb developmental defects plus abnormal hindbrain patterning, but no optic vesicle defects were observed. Maternal RA administration rescues many defects in Raldh2 mutants, thus allowing further analysis by conditional rescue. Raldh1 null mutant mice recently generated in this laboratory are viable, but embryos suffer a lack of RA synthesis in the dorsal retina suggesting that retinal defects will be discovered upon further analysis. There have been no genetic studies reported on Raldh3. Further analysis of RALDHs should provide key information needed to understand human developmental eye defects. The overall goals of this project are to use null mutant mice to establish roles for RALDH1, RALDH2, and RALDH3 in eye RA synthesis, plus use these mutant mice as tools to further examine the mechanism of retinoid signaling in eye development. Mutant mice will be examined for developmental eye defects histologically and by in situ hybridization to detect disrupted gene expression in eye tissues. Mice carrying the RARE-lacZ marker gene will be used to detect endogenous RA in mutant embryos. Specific goals for this project will be as follows: (1) Use Raldh1 mutants to examine the effect of a lack of RA in the dorsal retina on retinal development and axonal pathfinding for retinofugal projections; (2) Examine the contribution of RALDH1 and RALDH2 to RA synthesis for eye development by comparison of conditionally RA-rescued Raldh2 mutants and Raldh1-Raldh2 double mutants; (3) Generate Raldh3 null mutant mice to examine the role of this gene in eye development.

视黄酸（RA）是维生素A（视黄醇）的代谢衍生物，在脊椎动物发育过程中对眼轴图案至关重要。 当视黄醇被代谢为视黄醛，然后代谢为RA时，发生类维生素A信号传导，RA作为调节基因表达的核类维生素A受体的配体。妊娠期维生素A缺乏或类维生素A受体无效突变导致类维生素A信号传导中断，导致眼轴发育异常。RA在眼睛中局部产生的机制以及RA如何调节眼睛的背腹图案的机制尚不清楚。 我们对视黄醇如何被生理激活形成RA的理解仍然模糊，但通过发现在眼睛中表达的三种类维生素A脱氢酶将视黄醇代谢为RA，即RALDH 1，RALDH 2和RALDH 3，所有醛脱氢酶（ALDH）家族的成员，已经有所改善。 在该实验室和另一个实验室中产生的Raldh 2无效突变小鼠揭示了在妊娠中期具有致死性的表型，具有巨大的躯干和前肢发育缺陷以及异常的后脑模式，但未观察到视泡缺陷。 母体RA给药挽救了Raldh 2突变体中的许多缺陷，从而允许通过条件挽救进行进一步分析。 最近在这个实验室产生的Raldh 1无效突变小鼠是可行的，但胚胎遭受缺乏RA合成在背侧视网膜表明视网膜缺陷将被发现后，进一步分析。 目前还没有关于Raldh 3的遗传学研究报告。 对RALDH的进一步分析应该提供了解人类发育性眼缺陷所需的关键信息。该项目的总体目标是使用无效突变小鼠来建立RALDH 1，RALDH 2和RALDH 3在眼睛RA合成中的作用，并使用这些突变小鼠作为工具来进一步研究类维生素A信号传导在眼睛发育中的机制。 将对突变小鼠进行组织学检查，并通过原位杂交检测眼组织中基因表达的破坏。 携带RARE-lacZ标记基因的小鼠将用于检测突变胚胎中的内源性RA。 本项目的具体目标如下：（1）利用Raldh 1突变体研究视网膜背侧缺乏RA对视网膜发育和离视网膜投射轴突寻路的影响;（2）通过比较条件性RA拯救的Raldh 2突变体和Raldh 1-Raldh 2双突变体，研究RALDH 1和RALDH 2对RA合成的贡献;（3）建立Raldh 3基因缺失突变小鼠模型，研究该基因在眼发育中的作用。