Pitx2: Molecular mechanisms in eye development & disease

Pitx2：眼睛发育的分子机制

基本信息

批准号：
6652638
负责人：
PHILIP J GAGE
金额：
$ 31.89万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-09-01 至 2005-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Glaucoma is the second leading cause of blindness overall in the United States and first among African Americans. Elevated intraocular pressure from defects in the iris and aqueous humor drainage system in the anterior segment frequently accompanies glaucoma. Retinal ganglion cell death leading to glaucoma apparently results from the insult of chronically high IOP but the underlying molecular mechanisms are not understood. The genetic regulatory networks governing normal development of anterior segment structures are also poorly understood. Mice provide ideal models for determining the basic mechanisms contributing to normal eye development and for molecularly analyzing genetic eye disease. Mutations in the bicoid-related homeobox gene PITX2 result in Axenfeld-Rieger Syndrome (ARS), an autosomal dominant disease resulting in congenital anterior segment defects and glaucoma. I have cloned Pitx2 from mice and used gene targeting to generate an allelic series (null, hypomorphic, and conditional) for Pitx2 in mice. Initial analysis of the null allele established a more widespread requirement for Pitx2 in eye development than predicted from the human phenotype. Homzygotes mutants have defects in the optic nerve and posterior parts of the eye. The goal of this proposal is to use these mice to analyze the basic mechanisms of Pitx2 function in normal eye development and to identify the molecular consequences of partial or complete loss of Pitx2 activity. We will assess the hypothesis that Pitx2 has distinct functions in the ocular neural crest and mesoderm lineages. Pitx2 expression in each lineage will be determined after using binary transgenic systems to mark each cell lineage. These marking systems will also be used to compare the fates of each lineage in wild type and Pitx2-/- eyes, and determine the genetic mechanisms that require Pitx2. ARS results from altered Pitx2 dosage, indicating certain steps in eye development are highly sensitive to varied PITX2 protein levels. We will vary Pitx2 gene dosage using the null and hypomorphic alleles to identify the specific developmental functions that are most to variations in PITX2 levels and determine the underlying molecular mechanisms. Finally, we will use chimeric mice to rescue the lethality of Pitx2-/- mice in order to analyze Pitx2 functions later in eye development. This multifaceted approach should provide specific mechanistic details about the multiple functions of Pitx2 in eye development and also promises to provide insight into more general fundamental mechanisms of periocular mesenchyme in development. This basic information is essential for understanding eye disease.

描述（由申请人提供）：青光眼是美国整体失明的第二大主要原因，在非洲裔美国人中是第一个。虹膜缺陷和前节中的水性幽默排水系统的眼内压升高，经常伴随着青光眼。视网膜神经节细胞死亡导致青光眼显然是由于慢性高IOP的侮辱而导致的，但尚不清楚潜在的分子机制。管理前部结构正常发展的遗传调节网络也很少了解。小鼠提供了确定有助于正常眼发育和分子分析遗传眼病的基本机制的理想模型。双聚体相关的同源基因pitx2突变导致Axenfeld-Rieger综合征（ARS），这是一种常染色体显性疾病，导致先天性前部缺陷和glaucoma。我从小鼠中克隆了PITX2，并使用基因靶向来生成小鼠PITX2的等位基因序列（null，hydormolic and Syfolofic and Condicallic）。对无效等位基因的初步分析比人类表型的预测，对眼睛发育的PITX2的最广泛要求。 Homzygotes突变体在眼睛的视神经和后部有缺陷。该建议的目的是使用这些小鼠在正常眼发育中分析PITX2功能的基本机制，并确定PITX2活性的部分或完全丧失的分子后果。我们将评估以下假设：PITX2在眼神经rest和中胚层谱系中具有不同的功能。使用二进制转基因系统标记每个细胞谱系后，将确定每个谱系中的PITX2表达。这些标记系统还将用于比较野生型和pitx2 - / - 眼中每个谱系的命运，并确定需要PITX2的遗传机制。 ARS是由PITX2剂量改变的结果，表明眼睛发育的某些步骤对不同的PITX2蛋白水平高度敏感。我们将使用无效和型型等位基因来改变PITX2基因剂量，以识别特定的发育函数，这些发育函数最适合PITX2水平的变化并确定基本的分子机制。最后，我们将使用嵌合小鼠挽救Pitx2 - / - 小鼠的致死性，以分析PITX2后来在眼睛发育中起作用。这种多方面的方法应提供有关PITX2在眼发育中多重功能的特定机械细节，并有望洞悉开发中眼周间质的更一般基本机制。此基本信息对于理解眼病至关重要。