TWIST AND Msx2 IN BOUNDARY FORMATION AND CRANIOSYNOSTOSIS

边界形成和颅缝闭合中的扭转和 Msx2

基本信息

批准号：
7260527
负责人：
Robert E. Maxson
金额：
$ 38.64万
依托单位：
UNIVERSITY OF SOUTHERN CALIFORNIA
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-08-01 至 2010-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7260527
关键词：
Address Apoptosis Biological Biological Markers Blur Boston Cells Chotzen Syndrome Class Congenital abnormal Synostosis Craniosynostosis Data Defect Development Developmental Biology Disease Elements Embryo EphA4 Receptor Ephrins Frontal bone structure Functional disorder Genes Genetic Growth Human LacZ Genes Lead Link Localized Mesenchyme Mesoderm Cell Morphogenesis Mus Mutant Strains Mice Neural Crest Osteoblasts Parietal Parietal bone structure Pathway interactions Pattern Phenotype Population Protein Overexpression Rate Research Personnel Role Series Signal Transduction Site Testing Time Transgenes Transgenic Mice Transgenic Organisms Up-Regulation Ursidae Family Wild Type Mouse base coronal suture coronal synostosis craniofacial gain of function gain of function mutation gene function loss of function loss of function mutation mutant programs promoter prospective research study transgene expression

项目摘要

DESCRIPTION (provided by applicant): This is a proposal to investigate the morphogenesis of the coronal suture and mechanisms of coronal synostosis. The long-term aim is to understand how boundaries between cellular compartments form, and how such boundaries function in growth control and patterning. The cellular mechanisms underlying craniosynostosis are largely unknown. Prevalent views, based largely on ex vivo approaches, seek to explain craniosynostosis in terms of the timing of differentiation or survival of osteoblast populations. Our results suggest that understanding the fundamental causes of craniosynostosis requires an analysis at a higher level of biological organization. Through an examination of the Twist mutant mouse, we found that synostosis of the coronal suture is associated with a defect in the boundary between neural crest-derived mesenchyme that forms the frontal bone and mesodermal-derived mesenchyme that forms the parietal bone. In an effort to identify other genes that function together with Twist in coronal suture development, we have uncovered evidence that perturbations in Eph-ephrin and Bmp signaling may contribute to these defects. That ephrin signaling may have a part in the Twist mutant phenotype is suggested by our observations (i) that ephrins A2 and A4, as well as their receptor, EphA4, are expressed in a highly localized manner in the developing coronal suture, (ii) and that their expression is altered in Twist mutant mice and restored to their wild type pattern in Msx2-Twist double mutants. That BMP signaling is involved is suggested by our observation that the gene encoding the Bmp antagonist, noggin, is upregulated in the prospective coronal suture of Twist mutant mice, and that transgenic overexpression of noggin causes a sutural defect similar to that seen in Twist mutants. Moreover, inactivation of Bmp4 in neural crest also causes fusion of the frontal and parietal bones at the coronal suture. These data lead us to the hypothesis that craniosynostosis in the Twist mutant is caused in part by a perturbations in gene networks that control boundary formation, and that these networks are likely to include elements of the Eph-ephrin and BMP pathways. Here we propose (i) to carry out a series of genetic experiments aimed at testing the hypothesis that Twist interacts functionally with the Eph-ephrin and BMP pathways in the patterning of the coronal suture; (ii) to test the hypothesis that Msx2 and Twist function cooperatively in a genetic cascade that regulates boundary formation and coronal suture development. This will entail an analysis both of coronal suture development and the expression of ephrinA2 and EphA4 in Msx2-Twist double mutants. Finally, we will examine the regulatory relationship between Msx2 and Twist. We will investigate the mechanism by which reduced Twist function leads to expanded expression of Msx2, and we will determine whether upregulation of Msx2 is sufficient to cause a boundary defect and synostosis in the coronal suture. The significance of the proposed studies is, first, that they will contribute information on the pathophysiology of an important class of craniofacial disorders-the craniosynostoses. Second, they will address the biological significance of boundary formation in patterning and growth control-a fundamental problem in developmental biology.

描述（由申请人提供）：这是研究冠状缝合线和冠状突触机制的形态发生的建议。长期的目的是了解细胞隔室之间的边界形式以及这种边界如何在生长控制和模式中发挥作用。颅骨突出发生的细胞机制在很大程度上尚不清楚。普遍的观点主要基于离体方法，试图根据成骨细胞种群的分化或生存时间来解释颅突。我们的结果表明，了解颅突的基本原因需要在更高水平的生物组织中进行分析。通过检查扭曲突变小鼠的检查，我们发现冠状缝合线的阴影与神经rest衍生的间充质之间的边界缺陷有关，形成了形成额骨骨的额叶和中胚层衍生的间质。为了鉴定其他与冠状缝合线发育的扭曲一起起作用的基因，我们发现了证据表明，Eph-磷和BMP信号传导的扰动可能有助于这些缺陷。我们的观察结果（i）提出了Ephrin信号传导可能参与扭曲突变表型，即以Ephrins A2和A4及其受体Epha4的表达在发育中的冠状缝合物中以高度局部的方式表达。我们的观察结果表明，编码BMP拮抗剂Noggin的基因在扭曲突变体小鼠的前瞻性冠状缝合中上调，而Noggin的转基因过表达导致与扭曲突变体类似的缝合缺陷。此外，神经rest中BMP4的灭活还会导致冠状缝合线的额叶和顶骨融合。这些数据使我们提出了这样一个假设，即扭曲突变体中的颅突变是由控制边界形成的基因网络中的扰动引起的，并且这些网络可能包括Eph-磷林和BMP途径的元素。在这里，我们建议（i）进行一系列旨在测试扭曲在冠状缝合线上与eph-磷和BMP途径相互作用的假设的基因实验。（ii）检验以下假设：MSX2和Twist在调节边界形成和冠状缝合发育的遗传级联中合作。这将需要分析冠状缝合线发育，以及在MSX2-TWIST双突变体中Ephrina2和Epha4的表达。最后，我们将研究MSX2与扭曲之间的调节关系。我们将研究降低扭曲功能导致MSX2表达的机制，我们将确定MSX2的上调是否足以引起冠状缝合线中的边界缺陷和阴影。拟议研究的意义首先是，它们将为一类重要类型的颅面疾病的病理生理学提供信息。其次，他们将解决边界形成在模式和生长控制中的生物学意义 - 发育生物学中的基本问题。