Molecular Patterning of Mammalian Dentition

哺乳动物牙列的分子模式

• 批准号: 8733649
• 负责人: RULANG JIANG
• 金额: $ 51.68万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-20 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8733649
• 关键词: Activins; Automobile Driving; Bioinformatics; Biological Assay; Biological Models; Congenital Abnormality; Data; Defect; Dentition; Development; Embryo; Epithelium; Exhibits; Failure; Gene Expression Profiling; Gene Targeting; Generations; Genes; Genetic; Genetic Transcription; Human; Incisor; Lead; MSX1 gene; Mandible; Maxilla; Mesenchymal; Mesenchyme; Molar tooth; Molecular; Morphogenesis; Mus; Mutant Strains Mice; Mutation; Neural Crest; Odontogenesis; Organ; Organ Culture Techniques; Organogenesis; Pathway interactions; Pattern; Proteins; Regulation; Research Project Grants; Role; Signal Pathway; Signal Transduction; Staging; Supernumerary Tooth; Testing; Tissues; Tooth Germ; Tooth structure; Transducers; WNT Signaling Pathway; WNT10A gene; activin A; base; cleft lip and palate; comparative; improved; in vivo; mRNA Expression; mutant; novel; novel therapeutics; oral cavity epithelium; public health relevance; transcription factor

DESCRIPTION (provided by applicant): Tooth development has long been used as a powerful model system for studying the molecular mechanisms regulating organogenesis and the pathogenic mechanisms of tooth developmental anomalies in humans. A critical step in tooth development is the activation of odontogenic potential in the neural crest-derived tooth mesenchyme, which is responsible for driving tooth morphogenesis from the tooth bud stage and is sufficient to induce tooth organogenesis when recombined with non-dental epithelium. Failure to activate mesenchymal odontogenic potential is associated with tooth bud developmental arrest, as seen in mice lacking the Msx1 transcription factor. Mutations in MSX1 are also associated with tooth agenesis in humans. Previous studies suggested that Bmp4 is an important odontogenic signal downstream of Msx1. Bmp4 mRNA expression was downregulated in Msx1-/- tooth mesenchyme. However, we found that mice with neural crest specific inactivation of the Bmp4 gene exhibit developmental arrest of only the mandibular molar buds but their maxillary molars and incisors developed to mineralized teeth. We carried out RNAseq analyses of microdissected tooth bud mesenchyme and found that the mandibular molar mesenchyme expresses much higher levels of secreted Wnt antagonists than does the maxillary molar mesenchyme. We found that tissue- specific inactivation of ?-catenin, the obligatory transducer of canonical Wnt signaling, in the early tooth mesenchyme caused tooth bud developmental arrest, suggesting that the higher levels of Wnt antagonists in mandibular molar tooth mesenchyme contribute to the dramatic differences in maxillary and mandibular molar tooth defects in the Bmp4 mutant mice. Moreover, we discovered recently that inactivation of the Osr2 transcription factor caused supernumerary tooth formation from oral epithelium lingual to the molar tooth germs in mice. Osr2 is expressed in a gradient pattern and suppressed the domain of mesenchymal odontogenic potential along the buccolingual axis of the developing tooth mesenchyme. Whereas Msx1-/- mutant mice had tooth development arrested at the bud stage, Msx1-/-Osr2-/- double mutants exhibited nearly normal first molar morphogenesis but did not initiate supernumerary tooth development. Moreover, we found that Msx1 and Osr2 regulate antagonistically the expression of secreted Wnt antagonists in the developing tooth mesenchyme. Together, these data suggest novel mechanisms involving Bmp, Msx1, Osr2, and Wnt signaling pathways in the regulation of mesenchymal odontogenic potential. The major aims of this project are to identify, characterize, and integrate the molecula mechanisms combining these factors and pathways regulating early odontogenesis, using multifaceted experimental approaches, including in vivo pharmacological rescue, nanogram scale RNAseq-based gene expression profiling, and combined explant organ culture and genetic functional assays. Data from this project will significantly improve the current understanding of the molecular mechanisms of tooth development and multiple human birth defects and will facilitate development of new therapeutic strategies.

描述（由申请人提供）：长期以来，牙齿发育已被用作一个强大的模型系统，用于研究调节器官发生的分子机制和人类牙齿发育异常的致病机制。牙齿发育的关键步骤是神经rest衍生的牙间质的牙源性潜力的激活，该牙齿源是从牙齿芽阶段驱动牙齿形态发生的，并且在与非牙科上皮重新组合时足以诱导牙齿器官发生。未能激活间充质的牙源性潜能与缺乏MSX1转录因子的小鼠相比，与牙齿芽的发育停滞有关。 MSX1中的突变也与人类的牙齿发生有关。先前的研究表明，BMP4是MSX1下游的重要牙源性信号。 BMP4 mRNA表达在msx1 - / - 牙齿间充质中下调。但是，我们发现BMP4基因的神经rest特异性失活的小鼠仅表现出仅对下颌摩尔芽的发育停滞，但它们的上颌磨牙和切牙发育为矿化牙齿。我们对微分区分牙齿芽间充质进行了RNASEQ分析，发现下颌摩尔间充质表达的分泌的Wnt拮抗剂比上颌上颌摩尔间充质的水平要高得多。我们发现，在早期的牙齿间充质引起牙齿芽的发育停滞中，组织 - 蛋白酶的组织特异性灭活？ - 蛋白质蛋白是强制性的wnt信号传导的强制性传感器，这表明在下颌和颌骨牙齿降低的上颌骨牙齿上有显着差异，在下颌摩尔牙齿质质中的较高wnt拮抗剂在bm ectects defects中有效差异。此外，我们最近发现，OSR2转录因子的失活导致小鼠口服上皮到摩尔牙齿的超级牙齿形成。 OSR2以梯度模式表达，并抑制了发育中牙间充质的横轴轴的间充质牙源性势的结构域。而MSX1 - / - 突变小鼠在芽阶段捕获了牙齿发育，而MSX1 - / - OSR2 - / - 双突变体显示出几乎正常的第一摩尔形态发生，但没有启动超牙齿发育。此外，我们发现MSX1和OSR2在发育中的牙齿间充质中分泌的Wnt拮抗剂的表达通过拮抗作用。总之，这些数据表明，在调节间充质源基因势调节中涉及BMP，MSX1，OSR2和Wnt信号通路的新型机制。该项目的主要目的是使用多方面的实验方法（包括体内药理学拯救，基于纳米酶的基于RNASEQ的基因基因表达分析和结合ePulent Opplant Oupplant Onpertant Organter Organ Organ Organ Organ Organ Organ Organ Organ Organter and compinant opplinate criptional crization ossed ossed ossed，识别，表征和整合结合了这些因素和调节早期发生的途径的分子机制和调节早期发生的途径的分子机制。该项目的数据将显着提高人们对牙齿发育和多种人类出生缺陷的分子机制的当前理解，并有助于发展新的治疗策略。