The Role of AP-2 in Craniofacial Development

AP-2 在颅面发育中的作用

• 批准号: 7904372
• 负责人: TREVOR J WILLIAMS
• 金额: $ 7.57万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7904372
• 关键词: AP-2 Family Transcription Factor; Affect; Alleles; Amino Acids; Animal Model; Binding; Biological Assay; Biological Models; Birth; Branchio-Oculo-Facial Syndromes; Cessation of life; Child; Cleaved cell; Cleft Lip; Congenital Abnormality; Coupled; DNA Binding; DNA Binding Domain; DNA Sequence; Data; Defect; Deformity; Development; Developmental Process; Diagnosis; Dimerization; Dominant-Negative Mutation; Dysmorphology; Ectoderm; Elements; Embryo; Embryonic Development; Face; Family member; Gene Components; Gene Family; Genes; Genetic; Goals; Growth; Growth and Development function; Head; Heart; Human; In Vitro; Individual; Infant; Inherited; Kidney; Knock-out; Knockout Mice; Knowledge; Lead; Limb structure; Link; Mediating; Missense Mutation; Modeling; Molecular; Morphogenesis; Mus; Mutate; Mutation; Neural Crest; Neurologic; Nose; Orthologous Gene; Parents; Patients; Pattern; Phenotype; Process; Proteins; Quality of life; Regulator Genes; Reporting; Role; Skeleton; Surface Ectoderm; Syndrome; System; TFAP2A gene; Technology; Teratogens; Testing; Tissues; Tooth structure; Transcriptional Activation; Transcriptional Regulation; Transgenes; Transgenic Organisms; Tretinoin; Zebrafish; base; combinatorial; craniofacial; cranium; design; enhancer-binding protein AP-2; experimental analysis; gastrulation; in vivo; innovation; insight; knockout gene; malformation; mouse model; mutant; oral tissue; orofacial; postnatal; prevent; protein function; public health relevance; recombinase

DESCRIPTION (provided by applicant): About 75% of birth defects involve the head, face, and oral tissues. Although orofacial clefts and other craniofacial malformations have clear environmental and genetic causes, insufficient information exists concerning the mechanisms of craniofacial development to enable the majority of these defects to be detected or prevented pre-natally. Our goal is to develop animal models of craniofacial malformations that will lead to mechanistic insight into the diagnosis and treatment of related human birth defects. We focus on the AP-2 family of transcription factors since these genes provide a link between the genetic and environmental causes of human birth defects affecting the face. In mouse and human, five separate genes encode the various AP-2 proteins. Three of these genes are expressed in the developing mouse face, Tcfap2a, Tcfap2b, and Tcfap2c encoding the proteins AP-2a, AP-2¿, and AP-2? respectively. The human gene encoding AP-2a is mutated in Branchio-Oculo-Facial Syndrome (BOFS) in which there are orofacial clefting defects. Similarly, mutations in the human gene encoding AP-2¿ cause Char syndrome, which is characterized by face, heart, and limb defects. Expression of Tcfap2a and Tcfap2c are also responsive to retinoic acid application both in vitro and in vivo and these genes form an important component of the gene regulatory network affected by this powerful teratogen. Single gene knockouts of the three mouse AP-2 genes discussed above all result in death during embryogenesis or soon after birth. Tcfap2b null mice do not display overt facial defects and die due to neurological and kidney problems. Tcfap2c null mice die during gastrulation, and so it has been more difficult to gauge the role of this gene in face formation. Tcfap2a has the most direct link to craniofacial development. The Tcfap2a null embryos display multiple defects including orofacial clefting and hypoplasia of the neural crest derived facial skeleton and this is mainly due to loss of AP-2a function in the surface ectoderm. Although Tcfap2a, Tcfap2b, and Tcfap2c have unique roles in development, recent data show that they also share redundant functions. Indeed, preliminary studies indicate that the facial phenotypes generated by compound knockouts of these genes are far more serious than the individual gene knockouts. Thus, the goal of this application is to determine how these proteins function together to regulate craniofacial formation. In Aim 1, we will generate a mouse model of BOFS, which we hypothesize inhibits AP-2 function via a dominant negative mechanism. In Aims 2 and 3 we will generate and analyze particular knockout combinations of the three AP-2 genes expressed in the face using tissue specific Cre-LoxP technology. The results of these analyses will reveal the combinatorial roles for the AP-2 genes in craniofacial morphogenesis and provide significant insight into the transcriptional control of facial development. PUBLIC HEALTH RELEVANCE: Birth defects affect ~ 3% of all infants born in the US - with about 75% of these involving the head, face, and oral tissues - and the presence of a major birth defect will frequently reduce the quality of life for both the child and the parents. Insufficient information exists concerning the mechanisms of craniofacial development to enable the majority of these defects to be detected or prevented pre-natally. We are using animal model systems to determine how normal and abnormal craniofacial development proceeds and to identify new mechanisms that mediate face formation so that we may apply this knowledge to understand and ultimately treat the origins of human facial birth defects.

描述（由申请人提供）：大约75%的出生缺陷涉及头部，面部和口腔组织。虽然口面裂和其他颅面畸形有明确的环境和遗传原因，但关于颅面发育机制的信息不足，无法在出生前发现或预防大多数这些缺陷。我们的目标是开发颅面畸形的动物模型，这将导致对相关人类出生缺陷的诊断和治疗的机械见解。我们专注于AP-2家族的转录因子，因为这些基因提供了人类出生缺陷的遗传和环境因素之间的联系，影响脸。在小鼠和人类中，五个独立的基因编码各种AP-2蛋白。其中三个基因在发育中的小鼠面部中表达，Tcfap 2a、Tcfap 2b和Tcfap 2c编码蛋白质AP-2a、AP-2 â和AP-2？分别编码AP-2a的人类基因在鳃-眼-面综合征（BOFS）中发生突变，其中存在口面裂隙缺陷。同样，编码AP-2的人类基因突变会导致查尔综合征，其特征是面部、心脏和肢体缺陷。Tcfap 2a和Tcfap 2c的表达也响应于视黄酸在体外和体内的应用，并且这些基因形成受这种强大的致畸剂影响的基因调控网络的重要组成部分。以上讨论的三个小鼠AP-2基因的单基因敲除均导致胚胎发生期间或出生后不久的死亡。tcfap 2b基因敲除的小鼠不会表现出明显的面部缺陷，也不会因神经和肾脏问题而死亡。tcfap 2c基因缺失的小鼠在原肠胚形成期间死亡，因此更难评估该基因在面部形成中的作用。tcfap 2a与颅面发育有最直接的联系。Tcfap 2a无效胚胎显示多种缺陷，包括口面裂和神经嵴衍生的面部骨骼发育不全，这主要是由于表面外胚层中AP-2a功能的丧失。虽然Tcfap 2a、Tcfap 2b和Tcfap 2c在发育中具有独特的作用，但最近的数据表明它们也具有冗余功能。事实上，初步研究表明，这些基因的复合敲除所产生的面部表型比单个基因敲除严重得多。因此，本申请的目标是确定这些蛋白质如何共同作用以调节颅面形成。在目标1中，我们将产生BOFS的小鼠模型，我们假设其通过显性负性机制抑制AP-2功能。在目的2和3中，我们将使用组织特异性Cre-LoxP技术产生并分析在面部中表达的三个AP-2基因的特定敲除组合。这些分析的结果将揭示AP-2基因在颅面形态发生中的组合作用，并为面部发育的转录控制提供重要的见解。公共卫生关系：出生缺陷影响到美国出生的所有婴儿的约3%-其中约75%涉及头部，面部和口腔组织-并且重大出生缺陷的存在通常会降低儿童和父母的生活质量。有关颅面发育机制的信息不足，无法在出生前检测或预防大多数此类缺陷。我们正在使用动物模型系统来确定正常和异常的颅面发育是如何进行的，并确定介导面部形成的新机制，以便我们可以应用这些知识来理解并最终治疗人类面部出生缺陷的起源。