STUDY OF THE FORMATION OF ENAMEL CRYSTALLITES BY AMELOGENINS

釉蛋白形成牙釉质微晶的研究

• 批准号: 7598369
• 负责人: WILLIAM J LANDIS
• 金额: $ 0.23万
• 依托单位: WADSWORTH CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7598369
• 关键词: Ameloblasts; Animals; Apatites; Archives; Atomic Force Microscopy; Caliber; Cells; Class; Computer Retrieval of Information on Scientific Projects Database; Cryopreservation; Data; Dental Enamel; Deposition; Dimensions; Electron Microscopy; Enamel Formation; Ethylene Glycols; Event; Extracellular Matrix; Funding; Grant; Growth; Human; Image; Institution; Investigation; Ions; Location; Mediating; Methods; Microscopy; Minerals; Modeling; Mus; Mutant Strains Mice; Mutation; Nanosphere; Preparation; Process; Proteins; Research; Research Personnel; Resources; Rodent; Sampling; Source; Specimen; Structure; Techniques; Thinking; Tissues; Tooth structure; United States National Institutes of Health; Vertebrates; Visit; abstracting; amelogenin; calcium phosphate; ethylene glycol; high voltage electron microscopy; man; mutant; novel; reconstruction; tomography; two-dimensional; voltage

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT: The formation of enamel in the teeth of vertebrates, including rodents and man, is mediated by specific cells, the ameloblasts, that synthesize and secrete a class of small proteins, the amelogenins, into the extracellular matrices of this tissue. At locations close to the points of secretion along the so-called Tomes' processes of the ameloblasts, the amelogenins have been proposed to undergo assembly into two- or three-dimensional arrays of nanospheres, ~20-25 nm in diameter. These arrays are thought to initiate the deposition of enamel, long ribbon-like crystallites chemically identified as apatite (a calcium phosphate) and themselves organized in three-dimensions. The assembly of nanospheres and their interactions wtih calcium and phosphate ions (in the extracellular matrices of the ameloblasts) leading to nucleation and growth of enamel mineral are poorly defined and understood. Conventional electron microscopy and atomic force microscopy have been used previously to help characterize these putative events, but both techniques have been limited in their utility and the interpretation of their resulting data. The principal reasons for the limitations lie in the use of sample preparation methods that alter enamel crystal composition or structure and, in the case of conventional electron microscopy, images that are two-dimensional rather that three. High voltage electron microscopy and tomographic imaging are technical approaches that hold promise of providing novel three-dimensional information on the assembly of nanospheres, their interaction with nascent enamel crystallites, and the elaboration of the mineral ribbons. Combined with anhydrous sample preparation, including the use of ethylene glycol or cryofixation that does not interfere with mineral composition or structure, high voltage microscopy and tomographic reconstruction of collected images should be extremely powerful in circumventing the uncertain techniques of analysis that have been applied earlier. In addition to investigations of normal enamel specimens obtained from mice as well accepted models for human tooth structure, two available mutant animals will also be examined. These mice contain known genetic alterations in the structure of their constituent amelogenin proteins and, as a result, they should mediate enamel crystallites that are different from those determined by normal amelogenins. In these studies of mouse mutants, high voltage and tomography will be applied to identify putative changes in their ameloblast nanosphere assembly and enamel mineral organization. In 2004, Dr. Landis visited the RVBC to review archived data from past years.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 抽象的： 脊椎动物（包括啮齿动物和人类）牙齿中牙釉质的形成是由特定细胞（成釉细胞）介导的，该细胞合成并分泌一类小蛋白质（釉原蛋白）到该组织的细胞外基质中。 在沿着所谓的成釉细胞 Tomes 突的分泌点附近的位置，牙釉蛋白被提议组装成直径约 20-25 nm 的二维或​​三维纳米球阵列。 这些阵列被认为引发了牙釉质的沉积，长带状微晶在化学上被鉴定为磷灰石（一种磷酸钙），并且本身以三维形式组织。 纳米球的组装及其与钙离子和磷酸盐离子（在成釉细胞的细胞外基质中）的相互作用导致牙釉质矿物质的成核和生长，目前尚不清楚和了解。 传统的电子显微镜和原子力显微镜以前曾被用来帮助表征这些假定的事件，但这两种技术在其实用性和对所得数据的解释方面都受到限制。 限制的主要原因在于使用的样品制备方法改变了牙釉质晶体组成或结构，并且在传统电子显微镜的情况下，图像是二维而不是三维的。 高压电子显微镜和断层成像技术方法有望提供有关纳米球组装、纳米球与新生釉质微晶相互作用以及矿物带精细加工的新颖三维信息。 与无水样品制备相结合，包括使用乙二醇或不干扰矿物成分或结构的冷冻固定，高压显微镜和收集图像的断层扫描重建应该非常有效地规避早期应用的不确定分析技术。 除了对从小鼠获得的正常牙釉质样本以及公认的人类牙齿结构模型进行研究之外，还将检查两种可用的突变动物。 这些小鼠的牙釉原蛋白结构中含有已知的遗传改变，因此，它们应该介导与正常牙釉蛋白所确定的牙釉质微晶不同的牙釉质微晶。 在这些小鼠突变体的研究中，将应用高电压和断层扫描来识别其成釉细胞纳米球组装和牙釉质矿物组织的假定变化。 2004 年，兰迪斯博士访问了 RVBC，审查了过去几年的存档数据。