The role of mTert-expressing stem cells in tooth formation and renewal

描述（由申请人提供）：成体牙齿干细胞在小鼠切牙的持续更新中起着关键作用。虽然最近的功能丧失和获得研究已经开始定义参与维持正常牙齿形态发生和更新的关键因素，其中包括Wnt/b-连环蛋白信号传导，但缺乏这些细胞的标记物阻碍了我们对它们的遗传特征和在切牙中的位置的理解。因此，建立直接鉴定、分离和研究这些细胞的工具将大大推进我们的研究。 了解它们在牙齿生物学中的作用，这可能最终导致改善对各种疾病的治疗选择，包括那些影响牙齿的疾病。端粒酶（Tert）活性防止细胞衰老，并且是再生组织中维持干细胞所必需的。最近对人类牙齿的分析已经确定了假定的牙齿干细胞中的端粒酶活性。我们已经产生并验证了转基因报告小鼠品系（mTert-GFP、mTert-CreER和mTert-rtTA），其允许鉴定、分离和遗传操作端粒酶表达细胞。以前，我们已经表明，mTert-GFP的表达标志着端粒酶表达的ES细胞，iPS细胞和自我更新的组织干细胞在血液和肠道。此外，最近的初步研究表明，mTert表达标志着骨髓来源的推定间充质干细胞的群体。此外，该群体内Wnt/β-连环蛋白信号传导的稳定导致骨稳态的显著变化，这与该群体的丧失一致。有趣的是，这些小鼠还表现出多生牙形成，表明mTert表达标志着参与牙齿更新的推定牙齿干细胞群体。鉴于我们惊人的初步结果，我们假设mTert表达是切牙内牙齿干细胞的生物标志物。对mTert表达细胞的进一步研究将使我们能够确定牙齿更新的因素和途径。因此，该提议旨在1）表型和功能上表征表达mTert的牙细胞和2）定义Wnt/B-连环蛋白信号传导在表达mTert的牙细胞中的作用。 公共卫生相关性：由于缺乏明确的牙齿干细胞标记物，阻碍了我们对这些细胞的自我更新和分化潜力以及它们在组织再生中的潜在作用的理解。我们已经开发了一种独特的小鼠模型，使我们能够研究端粒酶表达干细胞在牙齿生物学中的作用。这项研究的结果将识别和功能表征一个离散的牙齿干细胞群体，这可能最终导致影响牙齿的疾病的治疗选择得到改善。

DESCRIPTION (provided by applicant): Adult dental stem cells play a critical role in the continual renewal of the mouse incisor. Although recent loss and gain of function studies have begun to define key factors involved in maintaining normal tooth morphogenesis and renewal, which include Wnt/b-catenin signaling, the lack of markers for these cells has hampered our understanding of their genetic characteristics and location within the incisor. Therefore, establishing the tools to directly identify, isolate and study these cells will greatly advance our understanding of their role in tooth biology, which may ultimately lead to improved therapeutic treatment options for a wide range of diseases, including those affecting teeth. Telomerase (Tert) activity prevents cellular senescence and is required for maintenance of stem cells in regenerative tissues. Recent analysis of human teeth has identified telomerase activity within putative dental stem cells. We have generated and validated transgenic reporter mouse lines (mTert-GFP, mTert-CreER and mTert-rtTA) that allow for the identification, isolation and genetic manipulation of telomerase-expressing cells. Previously, we have shown that mTert-GFP expression marks telomerase-expressing ES cells, iPS cells and self-renewing tissue stem cells in blood and intestine. In addition, recent preliminary studies indicate that mTert expression marks a population of bone marrow-derived putative mesenchymal stem cells. Moreover, stabilization of Wnt/b-catenin signaling within this population results in dramatic changes in bone homeostasis consistent with a loss of this population. Interestingly, these mice also exhibit supernumerary tooth formation indicating that mTert expression marks a population of putative dental stem cells involved in tooth renewal. Given our striking preliminary results we hypothesize that mTert expression is a biomarker for dental stem cells within the incisor. Further study of mTert-expressing cells will allow us to identify the factors and pathways that underlie tooth renewal. Therefore, this proposal aims to 1) phenotypically and functionally characterize mTert-expressing dental cells and to 2) define the role of Wnt/b- catenin signaling in mTert-expressing dental cells. PUBLIC HEALTH RELEVANCE: A lack of definitive dental stem cell markers has hampered our understanding of the self- renewal and differentiation potential of these cells as well as thei prospective role in tissue regeneration. We have developed a unique mouse model that allows us to investigate the role of telomerase-expressing stem cells in tooth biology. Results from this study will identify and functionally characterize a discrete population of dental stem cells which may ultimately lead to improved therapeutic treatment options for diseases affecting teeth.