Developmental Genetics of the Pharyngeal Apparatus

咽器的发育遗传学

• 批准号: 7851312
• 负责人: BERNICE E MORROW
• 金额: $ 41.16万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7851312
• 关键词: 22q11; 22q11.2; Animal Model; Aorta; Binding Sites; Boxing; Candidate Disease Gene; Cardiac; Cell Communication; Cell Culture Techniques; Cell Proliferation; Cells; Complex; Congenital Abnormality; Congenital Heart Defects; Consensus; Data; Defect; Development; DiGeorge Syndrome; Distal; Embryo; Embryonic Development; Etiology; Fibroblast Growth Factor; Gene Expression; Gene Expression Profiling; Gene Family; Gene Targeting; Gene Transfer Techniques; Genes; Genetic; Genetic Transcription; Heart; Heart Atrium; Human; In Situ Hybridization; Lung; Mammalian Cell; Mediating; Mesenchyme; Mesoderm Cell; Molecular; Morphogenesis; Mus; Muscle; Mutant Strains Mice; Myocardial; Neural Crest; Neural Crest Cell; Parathyroid gland; Pathway interactions; Patients; Pharyngeal Apparatus; Public Health; Reporter; Research; Reverse Transcriptase Polymerase Chain Reaction; Right ventricular structure; Role; Shprintzen syndrome; Signal Transduction; Staging; Structure; Syndrome; System; Testing; Thymus Gland; Tissues; Transcription factor genes; Tretinoin; Wild Type Mouse; base; cell motility; craniofacial; developmental genetics; gain of function; gene interaction; insight; interest; member; mutant; novel; premature; programs; transcription factor

DESCRIPTION (provided by applicant): The development of the pharyngeal apparatus into the craniofacial region, thymus, parathyroid and cardiac outflow tract (OFT) involves complex gene interaction, making them highly sensitive to genetic and environmental insults. Velo-cardio-facial syndrome/DiGeorge syndrome is associated with hemizygous 22q11 deletions and characterized by defects in the derivatives of the pharyngeal apparatus. Tbx1, a T-box transcription factor, and the gene for VCFS/DGS in humans, is associated with defects in the same structures when inactivated in the mouse. The most serious defect in patients with the syndrome is OFT defects. Tbx1 is expressed in the multiple tissues in the pharyngeal apparatus including the second heart field (SHF) mesenchyme required for OFT development. The mouse serves as an excellent model organism to identify genes for OFT development because many aspects of its morphogenesis are shared with humans. To identify Tbx1 regulated genetic pathways in the SHF, we performed gene expression profiling of the caudal pharyngeal region in Tbx1-/- and wild type mouse embryos. Isl1, a key marker for the SHF, among selected others, were downregulated in Tbx1-/- mutants, while genes required for posterior specification of the first heart field (FHF), such as Raldh2, Gata4, and Tbx5, as well as a subset of atrial-specific muscle contractile genes were ectopically expressed. Opposite expression changes concomitant with SHF-derived cardiac defects occurred in TBX1 gain-of- function mutants. Based upon these data, we hypothesize that Tbx1 positively regulates SHF cell proliferation and restricts premature differentiation in the caudal pharyngeal mesenchyme. Several genes important for the retinoic acid pathway, transcription factors and novel genes were found in the microarrays. We propose to characterize the most biologically interesting genes in order to build the genetic pathway downstream of Tbx1 in the SHF using null, conditional loss- and gain-of-function mutant mouse embryos. To identify direct downstream target genes of Tbx1, reporter systems will be used in mammalian cells. Tissue interactions are required for neural crest cell (NCC) migration and OFT septation, defective in VCFS/DGS and mouse mutants. Recently, Crkl, another gene deleted on 22q11.2, was shown to mediate Fgf8 signaling downstream of Tbx1. To test this hypothesis in the SHF and in NCCs, embryos with pan-mesodermal and neural crest inactivation of Crkl, respectively, will be analyzed for altered expression of Fgf responsive genes and SHF genes characterized. Using genes identified by microarray studies and conditional mutants we will be able to dissect the genetic pathway of Tbx1 in the SHF and NCCs for OFT development from the pharyngeal apparatus. Narrative: The relevance of this research to public health is that this program will enable us to find genes that cause birth defects. By taking genetics approaches in model organisms, we can obtain insights that would otherwise not be possible in humans.

描述（由申请人提供）：咽器发育为颅面区、胸腺、甲状旁腺和心脏流出道（OFT）涉及复杂的基因相互作用，使其对遗传和环境损伤高度敏感。Velo-cardio-facial综合征/DiGeorge综合征与半合子22 q11缺失相关，特征为咽器衍生物缺陷。Tbx 1是一种T-box转录因子，也是人类VCFS/DGS的基因，当在小鼠中失活时，与相同结构的缺陷相关。该综合征患者最严重的缺陷是OFT缺陷。Tbx 1在咽器的多种组织中表达，包括OFT发育所需的第二心脏区域（SHF）间充质。小鼠作为一个很好的模式生物，以确定基因的OFT发展，因为它的形态发生的许多方面与人类共享。为了确定Tbx 1调节的遗传途径在SHF，我们进行了基因表达谱的尾部咽部区域Tbx 1-/-和野生型小鼠胚胎。Isl 1是SHF的关键标志物，在Tbx 1-/-突变体中下调，而第一心野（FHF）后向特异性所需的基因，如Raldh 2，Gata 4和Tbx 5，以及心房特异性肌肉收缩基因的子集异位表达。TBX 1功能获得性突变体伴随SHF衍生的心脏缺陷发生相反的表达变化。基于这些数据，我们假设Tbx 1正调控SHF细胞增殖，并限制在尾咽间充质的过早分化。在微阵列中发现了几个对维甲酸途径重要的基因、转录因子和新基因。我们建议，以建立Tbx 1在SHF使用空，条件性丧失和获得功能突变小鼠胚胎的遗传途径下游的最具生物学意义的基因的特征。为了鉴定Tbx 1的直接下游靶基因，将在哺乳动物细胞中使用报告系统。神经嵴细胞（NCC）的迁移和OFT分隔，在VCFS/DGS和小鼠突变体缺陷的组织相互作用是必需的。最近，在22q11.2上缺失的另一个基因Crkl被证明介导Tbxl下游的Fgf 8信号传导。为了在SHF和NCC中检验这一假设，将分别分析具有Crkl的全中胚层和神经嵴失活的胚胎的Fgf应答基因的改变的表达，并表征SHF基因。使用微阵列研究和条件突变体鉴定的基因，我们将能够解剖Tbx 1在SHF和NCC中的遗传途径，用于从咽器发育OFT。这项研究与公共卫生的相关性在于，这项计划将使我们能够找到导致出生缺陷的基因。通过在模式生物中采用遗传学方法，我们可以获得在人类中不可能获得的见解。