DMP1 Mutations: Defects in Odontogenesis

DMP1 突变：牙发育缺陷

• 批准号: 7841051
• 负责人: JIAN Q. FENG
• 金额: $ 1.47万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-02 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7841051
• 关键词: Amino Acids; Animal Model; Applications Grants; Bypass; C-terminal; Cell Nucleus; Cells; Clinical; Complex; Data; Defect; Dental; Dental Pulp; Dentin; Dentin Formation; Dentinogenesis; Dentition; Development; Disease; Drug Formulations; Event; Exhibits; Familial hypophosphatemic bone disease; Functional disorder; Gene Mutation; Generations; Genes; Genetic Transcription; Goals; Human; In Vitro; Individual; Intervention; Knockout Mice; Lead; Light; MAP Kinase Gene; MAP Kinase Signaling Pathways; Mediating; Minor; Molecular; Molecular Analysis; Molecular Genetics; Morphogenesis; Mus; Mutation; Odontoblasts; Odontogenesis; One-Step dentin bonding system; Oral health; Osteogenesis; Pathogenesis; Pathway interactions; Patients; Pattern; Peptide Fragments; Phenotype; Physiological; Physiology; Play; Prevention; Process; Production; Proteins; Pulp Chambers; Regulation; Research; Research Proposals; Role; Signal Pathway; Signal Transduction; Staging; Testing; Therapeutic; Therapeutic Intervention; Tooth Abnormalities; Tooth structure; Transcriptional Regulation; Transgenic Mice; Width; Work; biomineralization; cell growth; dentin matrix protein 1; falls; gain of function; improved; in vivo; insight; mineralization; mouse model; novel; programs; promoter; public health relevance; research study; tool; transcription factor; wisdom tooth

DESCRIPTION (provided by applicant): Tooth development requires the precise spatial and temporal coordination of programs for cell growth, differentiation, and mineralization. In a search for genes required for normal tooth morphogenesis we have studied Dentin matrix protein1 (DMP1), a non- collagenous matrix protein highly expressed in pulp/odontoblast cells, using in vivo loss- and gain-of-function approaches. Dmp1-null mice display profound tooth abnormalities with enlarged pulp chambers, increased width of the predentin zone, hypomineralization, and delayed 3rd molar formation. Realizing that autosomal recessive hypophosphatemic rickets (ARHR) patients manifest phenotypic changes very similar to those observed in Dmp1-KO mice, we recently discovered two DMP1 mutations in these patients. We have concluded that these mutations are causes of the phenotypes resembling those of Dmp1-KO mice, although minor differences exist. In a search for mechanisms by which DMP1 controls odontogenesis, we unexpectedly observed a sharp reduction of osterix in the null pulp/odontoblasts. Osterix is a transcriptional factor that is essential for osteogenesis but its role in odontogenesis is unknown. Targeted re-expression of DMP1 in Dmp1-KO pulp/odontoblast cells restores osterix expression and rescues the defects in tooth formation. Notably, we found similar dentin abnormalities in Dmp1-KO, and osterix (conventional or conditional) KO mice. Therefore, we propose that DMP1 mutations are the cause of dentin defects in ARHR patients, and that DMP1 regulates osterix expression at an early stage of tooth development, which plays a critical role for odontogenesis. To test this hypothesis we will study the molecular genetics and pathophysiology of DMP1 mutations through creation of a mouse model with DMP1 mutations. We will also determine the mechanisms by which DMP1 modulates odontogenesis through Osterix via direct action at the nucleus and/or MAPK pathways. The successful completion of these studies will lead to 1) generation of an animal model mimicking these human mutations; 2) understanding the mechanism by which DMP1 controls odontogenesis through osterix via a direct mechanism within the nucleus level and/or MAPK signaling; and 3) identification of bioactive fragment(s) of DMP1 which can ultimately be used in translational applications that will benefit the public by providing therapeutic approaches corresponding to genetic alterations, leading to improved dental/oral health. PUBLIC HEALTH RELEVANCE: Patients with autosomal recessive hypophosphatemic rickets (ARHR) patients manifest phenotypic changes very similar to dentin defects we observed in Dmp1-KO mice. Our discovery of DMP1 mutations in these patients led to the formulation of the current research proposal. Our successful completion of these studies will provide mechanistic details about dentin formation, and will ultimately shed light on the prevention of structural defects in dentin. In addition, the mouse models which to be generated from these studies can be used to correlate individual gene mutations with the appropriate clinical intervention.

描述（由申请人提供）：牙齿发育需要细胞生长、分化和矿化程序的精确空间和时间协调。在寻找正常牙齿形态发生所需的基因时，我们使用体内功能丧失和功能获得方法研究了牙本质基质蛋白1（DMP1），这是一种在牙髓/成牙本质细胞中高度表达的非胶原基质蛋白。 Dmp1缺失小鼠表现出严重的牙齿异常，包括牙髓腔扩大、前牙本质区宽度增加、矿化不足和第三磨牙形成延迟。我们认识到常染色体隐性遗传性低磷血症性佝偻病 (ARHR) 患者表现出的表型变化与 Dmp1-KO 小鼠中观察到的表型变化非常相似，因此我们最近在这些患者中发现了两种 DMP1 突变。我们得出的结论是，这些突变是导致与 Dmp1-KO 小鼠表型相似的原因，尽管存在细微差异。在寻找 DMP1 控制牙生成的机制时，我们意外地观察到空牙髓/成牙本质细胞中 osterix 的急剧减少。 Osterix 是一种对于成骨至关重要的转录因子，但其在牙发育中的作用尚不清楚。在 Dmp1-KO 牙髓/成牙本质细胞中定向重新表达 DMP1 可恢复 osterix 表达并挽救牙齿形成的缺陷。值得注意的是，我们在 Dmp1-KO 和 osterix（常规或条件）KO 小鼠中发现了类似的牙本质异常。因此，我们提出DMP1突变是ARHR患者牙本质缺陷的原因，并且DMP1在牙齿发育的早期阶段调节osterix的表达，这在牙发育中起着关键作用。为了检验这一假设，我们将通过创建具有 DMP1 突变的小鼠模型来研究 DMP1 突变的分子遗传学和病理生理学。我们还将确定 DMP1 通过 Osterix 通过细胞核和/或 MAPK 途径的直接作用调节牙发育的机制。这些研究的成功完成将导致1）产生模仿这些人类突变的动物模型； 2) 了解 DMP1 通过核水平和/或 MAPK 信号传导内的直接机制通过 osterix 控制牙发育的机制； 3) 鉴定 DMP1 的生物活性片段，该片段最终可用于转化应用，通过提供与遗传改变相对应的治疗方法，使公众受益，从而改善牙齿/口腔健康。公共卫生相关性：常染色体隐性遗传性低磷血症佝偻病 (ARHR) 患者表现出的表型变化与我们在 Dmp1-KO 小鼠中观察到的牙本质缺陷非常相似。我们在这些患者中发现 DMP1 突变，从而制定了当前的研究计划。我们成功完成这些研究将提供有关牙本质形成的机制细节，并最终为预防牙本质结构缺陷提供线索。此外，从这些研究中产生的小鼠模型可用于将个体基因突变与适当的临床干预相关联。