REGULATION OF PITX2 IN DENTAL DEVELOPMENT

PITX2 在牙齿发育中的调控

• 批准号: 6483416
• 负责人: ANDREW F RUSSO
• 金额: $ 12.37万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6483416
• 关键词: bone morphogenetic proteins; congenital dentition disorder; dental development; developmental genetics; embryo /fetus; gene environment interaction; gene expression; homeobox genes; laboratory mouse; molecular pathology; protein protein interaction; tissue /cell culture; transcription factor

Tooth development is a complex morphogenetic process that involves both intrinsic genetic cues and epigenetic environmental signals. Recent studies have begun to reveal some of the regulators of tooth morphogenesis, including homeodomain transcription factors and bone morphogenic proteins (BMPs). The focus of this application is a novel homeodomain gene that is linked to Rieger syndrome. Rieger syndrome is characterize by morphogenetic abnormalities that include dental hypoplasia. The Rieger gene, now termed Pitx2, is a member of the bicoid-like family and has transactivation activity. It is the earliest known marker in the tooth primordia and is believed to play a key role in early tooth morphogenesis. However, the mechanisms that regulated Pitx 2 expression and function are not known. For example, our preliminary data on Pitx2 transactivation suggests a novel inhibitory role for the C-terminal domain. Furthermore, Pitx2 expression requires an unknown mesenchymal signal and additional factors are clearly needed for full transactivation activity. A major objective of this application will be to answer the question, what are the factors and signals that regulate Pitx2 function? We propose to first establish a working model of Pitx2 functional domain. In this context we will ask how does the C- terminal region inhibit transactivation and how do the naturally occurring Rieger mutations affect Pitx2 function? We will then examine the mechanisms controlling Pitx2 expression and function. In the first set of experiments we will examine control of Pitx2 by signaling molecules. Since tooth formation relies on epithelial-mesenchymal interactions, we propose to test the hypothesis that the extracellular signals BMP-4 and Sonic hedgehog (Shh) regulate Pitx2 expression in explant cultures. We will also test whether those agents activate Pitx2 promoter activity ion a model cell line. In the second set of experiments, we will ask if Pitx2 activity is controlled by physical interactions with oral epithelial transcription factors, as suggested by our preliminary studies using the Pit-1 protein. We will test interactions with known candidates that are co-expressed with Pitx2 in the dental epithelia, such as the Msx2 homeodomain protein. This approach will also enable us to identify novel interacting partners. We will then test the hypothesis that these protein interactions are important for Pitx2 function. These studies will provide the foundation for a better understanding of the molecular control of early tooth development.

牙齿发育是一个复杂的形态发生过程，既涉及内在遗传线索，也涉及表观遗传环境信号。最近的研究已经开始揭示一些牙齿形态发生的调节因子，包括同源结构域转录因子和骨形态发生蛋白(BMPs)。这项应用的重点是一个新的同源结构域基因，它与Rieger综合征有关。Rieger综合征的特征是形态发生异常，包括牙齿发育不良。Rieger基因，现在被命名为Pitx2，是类双核细胞家族的成员，具有反式激活活性。它是已知的牙齿原基中最早的标志物，被认为在早期牙齿形态发生中起关键作用。然而，调节PITX-2表达和功能的机制尚不清楚。例如，我们关于Pitx2反式激活的初步数据表明，C末端结构域具有新的抑制作用。此外，Pitx2的表达需要未知的间充质信号，显然需要额外的因子才能完全反式激活。这项应用的一个主要目标将是回答这个问题，什么是调节Pitx2功能的因素和信号？我们建议首先建立PITX2功能域的工作模型。在这种情况下，我们将询问C-末端区域如何抑制反式激活，以及自然发生的Rieger突变如何影响Pitx2功能？然后我们将研究控制Pitx2表达和功能的机制。在第一组实验中，我们将研究信号分子对Pitx2的控制。由于牙齿的形成依赖于上皮-间充质的相互作用，我们建议检验细胞外信号BMP-4和Sonic hedgehog(Shh)调节外植体培养中Pitx2表达的假设。我们还将测试这些试剂是否在模型细胞系中激活Pitx2启动子的活性。在第二组实验中，我们将询问Pitx2的活性是否受与口腔上皮转录因子的物理相互作用控制，正如我们使用Pit-1蛋白进行的初步研究所表明的那样。我们将测试与牙齿上皮细胞中与Pitx2共表达的已知候选基因的相互作用，例如MSX2同源结构域蛋白。这一方法还将使我们能够确定新的互动伙伴。然后我们将测试假设，这些蛋白质的相互作用是重要的Pitx2功能。这些研究将为更好地理解早期牙齿发育的分子控制提供基础。