Laboratory for the Study of Calcified Tissues and Biomaterials, Department of Stomatology, Faculty of Dental medicine Université de Montréal, Montréal, Québec, Canada.
Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Québec, Canada.
Sci Rep. 2017 Apr 24;7:46683. doi: 10.1038/srep46683.
A specialized basal lamina (sBL) mediates adhesion of certain epithelial cells to the tooth. It is distinct because it does not contain collagens type IV and VII, is enriched in laminin-332, and includes three novel constituents called amelotin (AMTN), odontogenic ameloblast-associated (ODAM), and secretory calcium-binding phosphoprotein proline-glutamine rich 1 (SCPPPQ1). The objective of this study was to clarify the structural organization of the sBL. Fluorescence and immunogold labeling showed that the three proteins co-localize. Quantitative analysis of the relative position of gold particles on the sBL demonstrates that the distribution of ODAM is skewed towards the cell while that of AMTN and SCPPPQ1 tends towards the tooth surface. Bacterial two-hybrid analysis and co-immunoprecipitation, gel filtration of purified proteins and transmission electron and atomic force microscopies highlight the propensity of AMTN, ODAM, and SCPPPQ1 to interact with and among themselves and form supramolecular aggregates. These data suggest that AMTN, ODAM and SCPPPQ1 participate in structuring an extracellular matrix with the distinctive capacity of attaching epithelial cells to mineralized surfaces. This unique feature is particularly relevant for the adhesion of gingival epithelial cells to the tooth surface, which forms a protective seal that is the first line of defense against bacterial invasion.
一种特化的基底层 (sBL) 介导某些上皮细胞与牙齿的黏附。它的独特之处在于它不包含 IV 型和 VII 型胶原蛋白，富含层粘连蛋白-332，并包含三种新的成分，分别称为牙釉蛋白 (AMTN)、牙源性成釉细胞相关蛋白 (ODAM) 和富含脯氨酸-谷氨酸的分泌性钙结合磷蛋白 1 (SCPPPQ1)。本研究的目的是阐明 sBL 的结构组织。荧光和免疫金标记显示这三种蛋白质共定位。对 sBL 上金颗粒相对位置的定量分析表明，ODAM 的分布偏向细胞，而 AMTN 和 SCPPPQ1 的分布则倾向于牙面。细菌双杂交分析和共免疫沉淀、纯化蛋白的凝胶过滤以及透射电子和原子力显微镜突出了 AMTN、ODAM 和 SCPPPQ1 与彼此相互作用并形成超分子聚集体的倾向。这些数据表明，AMTN、ODAM 和 SCPPPQ1 参与构建一种具有将上皮细胞附着到矿化表面的独特能力的细胞外基质。这一独特特征对于附着在牙面的牙龈上皮细胞的黏附尤为重要，因为它形成了一个保护性密封，是抵御细菌入侵的第一道防线。
