Molecular Mechanisms of PITX2 During Craniofacial Development

描述(申请人提供)：近年来，一些新的基因被鉴定出来，它们与牙齿形态发生有关。尽管在识别新的基因和调控牙齿发育的形态发生阶段的信号机制方面已经取得了很大进展，但调控成牙本质细胞和成釉细胞增殖和分化的转录机制却知之甚少。更好地了解这一过程的机制是必要的，这不仅是为了了解正常的牙齿形态发生，也是为了再生牙齿，并最终能够开发和提供更好的治疗策略。PITX2在牙齿发育的最早阶段选择性表达，为研究牙齿形成的分子调控提供了独特的工具。我们只是刚刚开始了解PITX2的分子机制，它在牙齿发育中的作用，以及参与颅面/牙齿发育的转录因子的下游层次。这项持续的拨款申请的重点是了解PITX2与其他因素相互作用以调节牙齿发育的分子机制。我们先前的研究结果表明，PITX2与其他因子协同作用，调节基因表达。我们建议验证我们的假设，即PITX2通过与T-box因子TBX1和TBX18以及LIM同源结构域因子Islet-1和Lhx6的特定蛋白质-蛋白质相互作用来差异调节基因的表达。HMG-17是一种染色质相关因子，通过Wnt/-catenin信号通路将PITX2重新招募到活性染色质中。我们将检验我们的假设，即PITX2的转录活性在发育过程中受到严格调控，它与HMG-17、-catenin、乙酰化组蛋白和染色质重塑因子相互作用。MicroRNAs(miR‘s)是调控基因表达的关键基因，但对其在颅面/牙齿发育中的作用知之甚少。初步数据显示，miR直接控制门牙和磨牙的模式，为正常的颅面/牙齿发育指定了miR表达的组合代码。我们将验证我们的假设，即特定的miR在牙齿发育过程中表达控制特定转录因子的活动和牙齿的模式。了解这些成分如何相互作用促进正常的头面部发育将进一步加深我们对遗传缺陷的理解。 公共卫生相关性：识别与颅面/牙齿发育有关的新基因将增加我们对正常胚胎发育所需的基本发育程序的了解。了解这些成分如何相互作用促进正常的头面部发育将进一步加深我们对遗传缺陷的理解。然后，一旦将分子基础分配给特定的缺陷或组件，我们就可以推广抑制严重颅面异常的方法。

DESCRIPTION (provided by applicant): In recent years a number of new genes have been identified that are involved in tooth morphogenesis. Though much progress has been made in identifying new genes and the signaling mechanisms that regulate morphogenetic stages of tooth development have been documented, the transcriptional mechanisms that regulate proliferation and differentiation of the odontoblasts and ameloblasts are poorly understood. Better understanding of the mechanistic aspect of this process is necessary, not only to understand normal tooth morphogenesis, but also to regenerate teeth, and eventually be able to develop and deliver better therapeutic strategies. PITX2 provides a unique tool for studying the molecular control of tooth formation since it is selectively expressed at the earliest stage of tooth development. We have only begun to understand the molecular mechanisms of PITX2, its role in tooth development and the downstream hierarchy of transcription factors involved in craniofacial/tooth development. The focus of this continuing grant application is to understand the molecular mechanisms by which PITX2 interacts with other factors to regulate tooth development. Our previous results demonstrate that PITX2 acts in concert with other factors to regulate gene expression. We propose to test our hypothesis that PITX2 differentially regulates gene expression through specific protein-protein interactions with T-box factors Tbx1 and Tbx18 and the LIM homeodomain factors Islet-1 and Lhx6. HMG-17, a chromatin associated factor recruits PITX2 to active chromatin and is activated through Wnt/-catenin signaling. We will test our hypothesis that the transcriptional activity of PITX2 is tightly regulated during development by its interaction with HMG-17, -catenin, acetylated histones and chromatin remodeling factors. MicroRNAs (miR's) are critical to controlling gene expression however little is known about their role in craniofacial/tooth development. Preliminary data demonstrates that miR's directly control the patterning of incisors and molars, specifying a combinatorial code of miR's expression for normal craniofacial/tooth development. We will test our hypothesis that specific miR's expressed during tooth development control the activities of specific transcription factors and the patterning of teeth. Understanding how these components interact to promote normal craniofacial development will further our understanding of genetic defects. PUBLIC HEALTH RELEVANCE: The identification of new genes involved in craniofacial/tooth development will increase our knowledge about the basic development programs required for normal embryogenesis. Understanding how these components interact to promote normal craniofacial development will further our understanding of genetic defects. We can then promote methodologies to inhibit severe craniofacial anomalies once a molecular basis has been assigned to a specific defect or component.