Osteoblast and Odontoblast Specific Regulatory Action of Runx2 for Bone and Tooth

Runx2 对骨和牙齿的成骨细胞和成牙本质细胞特异性调节作用

• 批准号: 8316770
• 负责人: Mitra D Adhami
• 金额: $ 4.8万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8316770
• 关键词: Ablation; Address; Age; Ameloblasts; Apical; Bone Development; Bone Matrix; Cartilage; Cell Lineage; Cells; Chondroblast; Chondrocytes; Cleidocranial Dysplasia; Collagen Type I; Complex; Dendrites; Dental Enamel; Dental Research; Dentin; Deposition; Development; Disease; Dysplasia; Embryo; Embryonic Development; Fibroblasts; Foundations; Gene Deletion; Gene Expression; Genes; Genetic; Health; Homeostasis; Human; Individual; Knock-out; Knockout Mice; Lead; Left; Link; Maintenance; Mesenchymal Stem Cells; Mesenchyme; Modeling; Molecular; Morphology; Mus; Mutation; Odontoblasts; Odontogenesis; Oral; Osteoblasts; Osteoclasts; Osteocytes; Osteogenesis; Osteopenia; Perinatal; Phase; Phenotype; Play; Process; Property; Reporting; Research; Role; Skeletal Development; Skeleton; Staging; Supernumerary Tooth; System; Testing; Therapeutic; Tissues; Tooth Germ; Tooth structure; Transgenic Mice; Transgenic Model; Transgenic Organisms; Variant; bone; cell type; clavicle; clinical application; craniofacial; in vivo; inhibitor/antagonist; intramembranous bone formation; long bone; malformation; mineralization; mouse model; novel; novel diagnostics; novel therapeutics; osteogenic; overexpression; postnatal; promoter; recombinase; skeletal; skeletal abnormality; skeletal dysplasia; skeletogenesis; tool; transcription factor

DESCRIPTION (provided by applicant): Runx2 is a critical component of skeletal development. Global knock-out studies have proven the role of Runx2 as a regulator for skeletal and tooth development. Runx2-null mice are born with a complete lack of mineralization, and tooth germs that arrest at the late cap/early bell stage. Furthermore, it has been shown that Runx2 is required for commitment from mesenchymal progenitor cells to the osteoblast, chondrocyte, and odontoblast lineages. Mutations in Runx2 gene lead to skeletal abnormalities in humans, such as Cleidocranial Dysplasia, which arises from haploinsufficiency of Runx2. This disorder is characterized by skeletal and craniofacial anomalies. Thus, understanding the specific functions of Runx2 has immense potential for clinical applications. Attempts to study the cell and tissue specific functions of Runx2 and its role in postnatal development have been unsuccessful. Transgenic mouse models manifest significant variation in their phenotypes, by contradicting the basic understandings of the role of Runx2 in normal development. For example, transgenic studies overexpressing Runx2 after the osteoblast-commitment phase report osteopenia, suggesting that Runx2 acts as an inhibitor in late stages of osteogenesis. However, it is known that gene expression of Runx2 increases throughout embryonic development, and Runx2 maintains high expression in postnatal development. I propose to employ a novel Runx2 floxed mouse model to accomplish Runx2 deletion in a cell type specific manner. We have previously confirmed this as a valid model for Runx2 gene ablation. For cell-type specific gene deletion, I will use the 2.3kb Type I Collagen promoter to drive Cre expression. Using this model, I will determine the function of Runx2 specifically in osteoblasts for skeletogenesis, and identify its role in odontoblasts for tooth formation. Furthermore, the expected viability of this mouse model passed the major postnatal developmental age will permit invaluable advances in bone and dental research. Our hypothesis is that Runx2 is required for maintenance of mature osteoblast phenotype and postnatal bone acquisition, and that the function of Runx2 in odontoblasts is essential for odontoblast maturation, and proper dentin and tooth formation. I will address this hypothesis by in vivo and ex vivo approaches by two specific aims: 1) Osteoblast specific regulatory role of Runx2 for skeletogenesis; and 2) Requirement of Runx2 for odontoblast maturation and tooth formation. The information obtained from these studies will provide a foundation for understanding the molecular mechanisms involved in both normal and abnormal osteogenic and dental development. This research will elucidate the role of tooth/bone matrix material properties in oral and skeletal health and disease. Eventually, the proposed studies will facilitate the development of novel diagnostic tools and therapeutic treatments regarding dentin matrix malformations, skeletal abnormalities, and craniofacial dysplasias. PUBLIC HEALTH RELEVANCE: These studies will contribute to our knowledge of how bone and tooth formation occurs normally, and also has the potential for development of novel therapeutics regarding dentin remodeling, and individuals with genetic or non-hereditary skeletal and craniofacial dysplasias.

描述（由申请方提供）：Runx 2是骨骼发育的关键组分。全球基因敲除研究已经证明Runx 2作为骨骼和牙齿发育的调节剂的作用。Runx 2基因敲除小鼠出生时完全缺乏矿化，牙胚在帽状晚期/钟状早期停滞。此外，已经表明Runx 2是间充质祖细胞向成骨细胞、软骨细胞和成牙本质细胞谱系定向分化所必需的。Runx 2基因的突变导致人类骨骼异常，例如锁骨颅骨发育不良，其由Runx 2的单倍不足引起。这种疾病的特点是骨骼和颅面畸形。因此，了解Runx 2的特定功能对于临床应用具有巨大的潜力。试图研究Runx 2的细胞和组织特异性功能及其在出生后发育中的作用一直不成功。转基因小鼠模型表现出显着的变化，其表型，矛盾的Runx 2在正常发育中的作用的基本理解。例如，在成骨细胞定型阶段后过表达Runx 2的转基因研究报告了骨质减少，表明Runx 2在骨生成的晚期阶段充当抑制剂。然而，已知Runx 2的基因表达在整个胚胎发育过程中增加，并且Runx 2在出生后发育中保持高表达。我建议采用一种新的Runx 2 floxed小鼠模型，以实现Runx 2删除细胞类型特异性的方式。我们之前已经证实这是Runx 2基因消融的有效模型。对于细胞类型特异性基因缺失，我将使用2.3kb I型胶原启动子来驱动Cre表达。使用这个模型，我将确定Runx 2的功能，特别是在成骨细胞的骨骼发育，并确定其在成牙本质细胞的牙齿形成的作用。此外，该小鼠模型通过主要出生后发育年龄的预期生存能力将允许骨骼和牙科研究的宝贵进展。我们的假设是，Runx 2是需要维持成熟的成骨细胞表型和出生后的骨收购，Runx 2在成牙本质细胞的功能是必不可少的成牙本质细胞的成熟，适当的牙本质和牙齿的形成。我将通过体内和离体方法通过两个特定的目的来解决这个假设：1）Runx 2对骨骼发生的成骨细胞特异性调节作用; 2）Runx 2对成牙本质细胞成熟和牙齿形成的要求。从这些研究中获得的信息将为理解正常和异常成骨和牙齿发育的分子机制提供基础。这项研究将阐明牙齿/骨基质材料特性在口腔和骨骼健康和疾病中的作用。最终，拟议的研究将促进新的诊断工具和治疗方法的发展，牙本质基质畸形，骨骼异常和颅面发育不良。 公共卫生关系：这些研究将有助于我们了解骨骼和牙齿正常形成的方式，并有可能开发关于牙本质重塑的新疗法，以及遗传或非遗传性骨骼和颅面发育不良的个体。