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: 8672628
• 负责人: Mitra D Adhami
• 金额: $ 4.62万
• 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 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8672628
• 关键词: Ablation; Address; Age; Ameloblasts; Apical; Bone Development; Bone Matrix; Cartilage; Cell Lineage; Cells; Chondroblast; Chondrocytes; Cleidocranial Dysplasia; Collagen Type I; Complex; Cre-LoxP; 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; public health relevance; 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.

描述（由申请人提供）：RUNX2是骨骼发育的关键组成部分。全球敲除研究证明了Runx2是骨骼和牙齿发育的调节剂的作用。 runx2-null小鼠出生时完全缺乏矿化，牙齿在后期/早期贝尔阶段被捕。此外，已经表明，Runx2是从间充质祖细胞到成骨细胞，软骨细胞和odontoblast谱系所必需的。 Runx2基因的突变导致人类的骨骼异常，例如cleid骨发育不良，这是由Runx2的单倍宽松引起的。该疾病的特征是骨骼和颅面异常。因此，了解RUNX2的特定功能在临床应用中具有巨大的潜力。尝试研究RUNX2的细胞和组织特异性功能及其在产后发育中的作用并没有成功。转基因小鼠模型通过与Runx2在正常发育中的作用相矛盾，表现出其表型的显着差异。例如，在成骨细胞 - 承诺阶段报告骨骨减少症之后过表达Runx2的转基因研究表明Runx2在成骨的后期起作用。然而，众所周知，RUNX2的基因表达在整个胚胎发育过程中都会增加，Runx2在产后发育中保持高表达。我建议采用一种新型的Runx2 Floxed小鼠模型以特定于细胞类型的方式完成Runx2缺失。我们以前已经确认这是Runx2基因消融的有效模型。对于细胞型特异性基因缺失，我将使用2.3kb I型胶原蛋白启动子来驱动CRE表达。使用此模型，我将在成骨细胞中专门确定runx2的功能以进行骨骼生成，并确定其在牙齿形成的牙糖细胞中的作用。此外，该小鼠模型的预期生存能力通过了产后主要的发育年龄将允许骨骼和牙科研究的宝贵进步。我们的假设是，Runx2是维持成熟成骨细胞表型和产后骨骼的必要条件所必需的，并且Runx2在odontoblasts中的功能对于牙糖细胞成熟以及适当的牙本质和牙齿形成至关重要。我将通过体内和离体方法通过两个具体目的来解决这一假设：1）runx2在骨骼生成中的成骨细胞特定的调节作用； 2）Runx2的需求对Odontoblast成熟和牙齿形成。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涉及的分子机制提供基础。这项研究将阐明牙齿/骨基质材料在口腔和骨骼健康和疾病中的作用。最终，拟议的研究将促进有关牙本质基质畸形，骨骼异常和颅面异常发育不良的新型诊断工具和治疗方法的开发。