Developmental Mechanisms of the Chromodomain Gene Chd7

染色质结构域基因 Chd7 的发育机制

• 批准号: 7849886
• 负责人: Donna M. Martin
• 金额: $ 26.42万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-17 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7849886
• 关键词: ATP phosphohydrolase; Adult; Affect; Alleles; Amino Acid Sequence; Antibodies; Binding; Biology; Brain; CHARGE syndrome; Cell Proliferation; Cells; Child; Chromatin; Clinical; Coloboma; Complex; Congenital Heart Defects; DNA; DNA Binding; Defect; Development; Diagnosis; Disease; Dyes; Ear; Embryo; Epigenetic Process; Epithelial Cells; Epithelium; Evolution; Exhibits; Family; Figs - dietary; Functional disorder; Galactosidase; Gene Expression; Gene Expression Regulation; Gene Targeting; Genes; Genetic; Genital system; Genotype; Growth; Growth and Development function; Hearing; Human; Immunofluorescence Immunologic; In Situ Nick-End Labeling; Knockout Mice; Knowledge; Labyrinth; Modeling; Morphology; Mus; Mutant Strains Mice; Neuroglia; Neurons; Newborn Infant; Organ; Paint; Pattern; Phenotype; Process; Protein Binding Domain; Proteins; Reporter; Reverse Transcriptase Polymerase Chain Reaction; Role; Scanning Electron Microscopy; Semicircular canal structure; Sensory; Testing; Tissues; Transcriptional Regulation; base; cell type; chromatin immunoprecipitation; chromatin remodeling; deafness; dosage; embryonic stem cell; equilibration disorder; helicase; improved; insight; malformation; member; mouse model; mutant; nerve stem cell; nerve supply; novel; otoconia; postnatal; promoter; public health relevance; relating to nervous system; research study; therapy development

DESCRIPTION (provided by applicant): These studies have direct relevance for improving our understanding of the developmental defects associated with Chd7 deficiency. Precise regulation of gene expression is critical for normal development of most tissues and organs. Chromodomain proteins, characterized by DNA binding and ATP-dependent helicase domains, have poorly understood roles in chromatin remodeling and exert epigenetic influences on gene expression. In humans, haploinsufficiency for CHD7, a member of the third subfamily of chromodomain proteins, causes CHARGE syndrome. CHARGE is a multiple anomaly disorder characterized by ocular coloboma, heart defects, atresia of the choanae, retarded growth and development, genital hypoplasia, and ear anomalies including deafness and vestibular disorders. We generated mice heterozygous for a gene trapped null allele (Chd7Gt/+). These mice exhibit many features similar to human CHARGE phenotypes, including severe inner ear defects and postnatal growth delays. Chd7Gt/+ mice also express a ¿-galactosidase reporter in Chd7-positive tissues, and can be used for tracking the fates of Chd7 deficient cells. The clinical features of CHARGE in humans and mice are variable and incompletely penetrant, and the most common developmental malformation in both humans and mice with loss of CHD7 function is semicircular canal dysgenesis or hypoplasia. Inner ear defects with Chd7 deficiency in mice are complex, and include malformations of the semicircular canals and innervation of sensory epithelia. Specific tissues and cell types appear uniquely sensitive to Chd7 dosage, but the cellular Chd7 expression patterns and mechanisms of Chd7 deficiency in cell proliferation, differentiation, and survival are not known. Moreover, CHD7 interacting partners and downstream targets in the ear and neural cells are not characterized. Such knowledge would help guide rational development of therapies for inner ear defects. Our global hypothesis is that CHD7 functions in a transcriptional complex to repress or activate downstream target genes in developing ear and neural tissues. We have three specific aims: (1) Characterize cell proliferation, survival, and differentiation in Chd7 mutant mice, (2) Determine the contributions of CHD7-expressing tissues to inner ear development, and (3) Characterize cultured inner ear and neural stem cells from wildtype and Chd7 mutant embryos, and use them to determine whether CHD7 directly binds the promoters of candidate target genes. Results of proposed experiments will bring novel insights into fundamental processes of chromatin remodeling and transcriptional regulation. Improved understanding of tissue-specific requirements for Chd7 might also improve the diagnosis and treatment of CHARGE-related inner ear and other developmental defects. PUBLIC HEALTH RELEVANCE: This project has direct relevance for understanding the mechanisms of CHD7 deficiency-induced hearing and balance disorders in children and adults with CHARGE syndrome. CHARGE syndrome is a multiple anomaly condition that affects 1 in 10,000 newborn children worldwide. Results of experiments described in this proposal will improve our understanding of genetic and epigenetic factors regulating basic chromatin biology, and their impact on development.

描述（由适用提供）：这些研究具有直接相关性，可以提高我们对与CHD7缺乏症相关的缺陷的理解。基因表达的精确调节对于大多数组织和器官的正常发育至关重要。以DNA结合和ATP依赖性解旋酶结构域为特征的染色体蛋白蛋白在染色质重塑中的作用不足，对基因表达的表观遗传学影响很少。在人类中，CHD7的单倍不足，是染色体蛋白第三个亚科的成员，导致电荷综合征。电荷是一种多重异常疾病，其特征是眼部coloboma，心脏缺陷，Choanae闭锁，迟滞的生长和发育，生殖器性发育不全以及包括耳聋和前庭疾病在内的耳朵异常。我们生成了杂合子的小鼠，以用于捕获的基因null等位基因（CHD7GT/+）。这些小鼠表现出许多类似于人类电荷表型的特征，包括严重的内耳缺陷和产后生长延迟。 CHHD7GT/+小鼠还在CHD7阳性时机中表达了 - 半乳糖苷酶报告基因，可用于跟踪CHD7缺乏细胞的命运。人类和小鼠电荷的临床特征是可变且不完全渗透的，并且在人类和小鼠中，CHD7功能丧失的最常见发育畸形是半圆形管失去障碍或发育不全。小鼠中CHD7缺乏症的内耳缺陷是复杂的，包括半圆形管的畸形和感觉上皮的神经支配。特定的组织和细胞类型似乎对CHD7剂量具有独特的敏感，但是尚不清楚细胞CHD7表达模式和CHD7缺乏症的机制。此外，CHD7相互作用的伴侣和耳朵中的下游靶标没有表征。这种知识将有助于指导内耳缺陷的疗法的合理发展。我们的全球假设是，CHD7在转录复合物中起作用，以反映或激活发育中的耳朵和神经组织中的下游靶基因。我们有三个具体的目标： （1）表征CHD7突变小鼠中细胞增殖，存活和分化， （2）确定表达CHD7的组织对内耳发育的贡献，以及 （3）表征了野生型和CHD7突变胚胎中培养的内耳和神经干细胞，并使用它们来确定CHD7是否直接结合候选靶基因的启动子。 提出的实验结果将使新的见解对染色质重塑和转录调控的基本过程。对CHD7组织特异性需求的了解的提高还可以改善与电荷相关的内耳和其他发育缺陷的诊断和治疗。公共卫生相关性：该项目与了解CHD7缺乏症引起的听力和平衡疾病的机制具有直接相关性。电荷综合征是一种多重异常情况，影响了全球10,000名新生儿中的1个。本提案中描述的实验结果将提高我们对遗传和表观遗传因素的理解，以应对基本染色质生物学及其对发育的影响。