Genetic Analysis of Tbx1 in Ear Disorders

耳部疾病中 Tbx1 的遗传分析

• 批准号: 7582716
• 负责人: BERNICE E MORROW
• 金额: $ 35.28万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-12-01 至 2013-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7582716
• 关键词: 22q11.2; Address; Alleles; Animal Model; Boxing; Cell Proliferation; Cells; Cochlea; Color; Congenital Abnormality; Data; Defect; Development; DiGeorge Syndrome; Disease; Dysplasia; Ear; Ear Diseases; Enhancers; Enzymes; Epithelium; Funding; Future; Ganglia; Gene Transfer Techniques; General Population; Genes; Genetic; Goals; Hearing Impaired Persons; Human; Human Genetics; Immunofluorescence Immunologic; Knowledge; Labyrinth; Lead; Learning; Left; Light; Link; Maps; Medical; Mesenchyme; Metabolic; Methods; Modeling; Molecular; Molecular Genetics; Morphogenesis; Mus; Mutant Strains Mice; Mutation; Myxoid cyst; Nature; Organ; Otic Vesicle; POU Domain; Pan Genus; Pathogenesis; Pathway interactions; Patients; Pattern; Process; Regulation; Regulatory Pathway; Research; Role; Sensorineural Hearing Loss; Sensory; Severities; Shprintzen syndrome; Signal Pathway; Signal Transduction; Signaling Pathway Gene; Syndrome; System; Testing; Tissues; Transcription factor genes; Tretinoin; Work; base; beta catenin; deafness; gain of function; gene environment interaction; genetic analysis; hearing impairment; in vivo; loss of function; malformation; morphogens; mouse model; neurogenesis; novel therapeutics; overexpression; programs; transcription factor

DESCRIPTION (provided by applicant): During the previous funding period, we found that Tbx1, encoding a T-box containing transcription factor, the gene for velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) on 22q11.2, is required in the otic vesicle (OV) and periotic mesenchyme (POM), for inner ear development. Mutations in Brn4 (Pou3f4), an X-linked POU domain containing transcription factor, causes DFN3. Patients with DFN3 have hearing loss and mice with inactivating mutations are deaf. Tbx1 and Brn4 are co-localized to the POM and genetically interact for cochlear outgrowth. Inactivation of Tbx1 in the mouse using a pan-mesodermal Cre driver, T-Cre, leaves the vestibular system intact but results in failed cochlear outgrowth. In Specific Aim 1, we propose to dissect the signaling pathways downstream of Tbx1 and Brn4 in the POM needed to for inner ear development using conditional loss and gain of function alleles of Tbx1. Upstream factors regulating expression of Tbx1 in the OV have not been identified. Preliminary data suggests that the Wnt/B-catenin signaling pathway may act upstream of Tbx1. In Specific Aim 2, we will determine the role of Wnt/B-catenin signaling in inner ear morphogenesis via Tbx1 using conditional B-catenin loss and gain-of-function mouse mutants. We will also take an unbiased approach in finding the OV enhancer using transient mouse transgenesis methods. Inactivation of Tbx1 in the otic vesicle results in a missing cochlea and vestibular system as well as a duplicated cochleovestibular ganglion rudiment, suggesting that it acts as a selector gene for inner ear morphogenesis. In Specific Aim 3, we will focus on the pathways downstream of Tbx1 to further understand its roles in restricting neurogenesis and promoting cell proliferation in the otic epithelium. This competitive renewal seeks to reveal the molecular genetic pathway of Tbx1 in inner ear development. This program will enable us to understand the molecular pathogenesis of VCFS/DGS and DFN3, two human genetic syndromes. Being able to inactivate or overexpress genes in mammalian model organisms will make it possible to learn about the genetic pathways upstream and downstream of Tbx1 and downstream of Brn4. In addition, Tbx1 and Brn4 may be required for modulating retinoic acid levels. Too much or too little retinoic acid causes birth defects including inner ear anomalies. The genes we identify may serve as genetic modifiers to alter the severity in patients with VCFS/DGS and DFN3 and may contribute to more commonly occurring sporadic birth defects in the general population. In addition, understanding cross talk between these genes and the retinoic acid and other morphogen pathways we study will shed light on gene-environment interactions, which will lead to novel therapeutics in the future. The goal of this project is to understand the molecular basis of inner ear defects in patients with congenital malformation disorders.

描述（由申请人提供）：在上一个融资期间，我们发现在22q11.2上编码包含转录因子的T-box，含有转录因子，即丝线 - 核心 - 元素综合征的基因/Digeorge综合征（VCFS/DGS），在Otecile（OV）和Enionechemechemechemechemephememememe（pome）中需要在22q11.2上进行。 BRN4中的突变（POU3F4）是含有转录因子的X连锁POU结构域的突变，导致DFN3。 DFN3患者的听力损失，而突变失活的小鼠聋。 TBX1和BRN4共定位于POM，并在遗传上相互作用以使人工耳蜗出现。使用Pan-Mesodermal CRE驱动器T-CRE在小鼠中灭活TBX1，使前庭系统完好无损，但导致耳蜗出现失败。在特定的目标1中，我们建议在使用条件损失和TBX1功能等位基因获得的内耳发育所需的POM中剖析TBX1和BRN4下游的信号传导途径。尚未鉴定出调节TBX1表达的上游因子。初步数据表明，Wnt/B-catenin信号通路可以在TBX1上游作用。在特定的目标2中，我们将使用条件B-catenin损失和功能性小鼠突变体来确定Wnt/B-catenin信号通过TBX1通过TBX1的形态发生的作用。我们还将采用一种无偏见的方法来使用瞬态小鼠转基因方法查找OV增强子。 TBX1在耳囊泡中的失活导致缺失的耳蜗和前庭系统以及重复的耳目白细胞神经节的含量，这表明它充当内耳形态发生的选择基因。在特定目标3中，我们将专注于TBX1下游的途径，以进一步了解其在限制神经发生和促进细胞增殖中的作用。这种竞争性更新旨在揭示内耳发育中TBX1的分子遗传途径。该程序将使我们能够理解VCFS/DGS和DFN3的分子发病机理，这是两个人类遗传综合征。能够在哺乳动物模型生物中灭活或过表达基因将使您了解TBX1上游和下游BRN4上游的遗传途径。另外，调节视黄酸水平可能需要TBX1和BRN4。视黄酸太多或太少会导致包括内耳异常在内的先天缺陷。我们识别的基因可以用作遗传修饰剂，以改变VCFS/DGS和DFN3患者的严重程度，并可能导致普通人群中更常见的零星出生缺陷。此外，了解这些基因与视黄酸与我们研究的其他形态学途径之间的串扰将阐明基因 - 环境相互作用，这将在未来导致新的治疗剂。该项目的目的是了解先天性畸形疾病患者内耳缺陷的分子基础。