CEMENTOGENESIS: ROLE OF HERTWIG'S EPITHELIAL ROOT SHEATH

描述(申请人提供)：尽管与调控牙齿发育的生长和转录因子相关的知识非常丰富，但与牙齿发育后期、矿化组织形成时所涉及的因素相关的信息仍然缺乏，对于调控牙根发育的因素的信息更是匮乏。本研究的长期目标是从形态、细胞和分子水平上了解牙根发育的过程，包括牙根牙本质和牙骨质形成的机制以及牙根附着在牙周韧带上的机制。在这一应用中，我们将重点介绍Hertwig上皮根鞘(HERS)细胞在根发育中的作用。尽管HERS细胞在根形成中的作用被广泛接受，但这些细胞的确切功能和命运仍然存在争议。这些细胞的功能从纯粹的结构实体(将牙齿外胚间充质组织细分为牙乳头和牙囊)，到调控牙根发育的时间，到诱导间充质细胞分化为成牙骨质细胞，再到作为成牙骨质细胞的前体。在这次竞争性更新中，我们将检验这样的假设，即根的发育是由她的细胞通过与周围间充质细胞的动态和相互作用启动的，导致萌芽形态发生，并且存在一个与这些组织相关的独特基因，该基因受NFI-C转录因子调控。我们建议通过利用新创建的NFI-C(核因子I-C)基因敲除小鼠来检验这一假设，该小鼠的独特表型是缺乏根的形成。此外，我们将使用已建立的永生细胞系(HERS、牙乳头间充质细胞(DPM)、牙囊)来实现以下特定目标：确定导致根形态发生的初始事件；确定根发育所必需的细胞相互作用；确定与根发育相关的分子；确定已确定的分子在根发育中的作用。包括原位杂交、组织重组、器官培养、细胞培养、微阵列技术等在内的广泛技术的使用将提供完成我们特定施舍所需的数据。这项研究中产生的数据将提供与根发育、HERS在这一过程中的作用以及参与根形成的调控因素有关的迫切需要的信息。虽然罕见，但有根发育不全的个体已经被记录在案。

DESCRIPTION (provided by applicant): Despite the tremendous knowledge related to the growth and transcription factors that regulate tooth development, there is still a lack of information related to the factors involved at later stages of tooth development, when the mineralized tissues are formed, and an even greater paucity of information as to the factors that regulate root development. It is the long-term objective of this study to understand the process of root development at the morphologic, cellular and molecular levels including the mechanisms underlying root dentin and cementum formation as well as root attachment to periodontal ligament in the healthy periodontium. In this application, we will focus on the role of Hertwig's Epithelial Root Sheath (HERS) cells in root development. Although the role of HERS cells in root formation is widely accepted, the precise function and fate of these cells remains controversial. Functions suggested for these cells have ranged from a pure structural entity (subdivide the dental ectomesenchymal tissues into dental papilla and dental follicle), to regulators of the timing of root development, to inducers for mesenchymal cells differentiation into cementoblasts, to being cementoblast cells precursors. In this competing renewal we will test the hypothesis that that root development is initiated by HERS cells through dynamic and reciprocal interactions with the surrounding mesenchyme resulting in budding morphogenesis and there is a unique gene associated with these tissues that is regulated by the NFI-C transcription factor. We propose to test this hypothesis by taking advantage of a newly created Nfi-c (Nuclear Factor I-C) knockout mice knock whose unique phenotype is that it lacks the formation of roots. In addition we will use established immortal cell lines (HERS, Dental Papillae Mesenchyme (DPM), dental follicle) to accomplish the following Specific Aims: To determine the initial events leading to root morphogenesis; To determine what kind of cell interactions are necessary for root development; To determine the molecules associated with root development; To determine the role of the molecules identified in root development. The use of a wide range of technology including in situ hybridization, tissue recombination, organ culture, cell culture, microarrays technology, etc. will provide the data required to accomplish our specific alms. The data generated in this study will provide much needed information related to root development, the role of HERS in this process and the regulatory factors involved in root formation. Although rare, individuals with root agenesis have been documented.