Gao Z, Mackenzie I C
Dental Branch/Dental Science Institute, University of Texas, Houston 77335.
Epithelial Cell Biol. 1992 Oct;1(4):156-67.
Epithelia differ regionally in their patterns of phenotypic expression. The junctional epithelium (JE) that attaches the oral mucosa to the teeth is a unique tissue that shows a pattern of differentiation unlike other oral epithelia and forms basal lamina against the non-vital tooth surface. The mechanisms that establish this unusual phenotype and the developmental origin of this epithelium are both uncertain. The formation of JE by downgrowth of the oral gingival epithelium (OGE) during tooth eruption has been suggested but morphological studies indicate that it may be derived from the reduced enamel epithelium (REE) that covers the crown of the unerupted tooth. These epithelia of potential origin differ in their developmental histories: intrinsic differences between them could thus significantly influence the phenotype of an epithelium formed from them. The patterns of phenotypic expression of specimens of dissected JE, OGE and REE, and of cell cultures of these epithelia grown under standardized conditions, were examined (1) by immunocytochemistry using monoclonal antibodies with specificity for individual cytokeratins, vimentin and ICAM-1, and (2) by two-dimensional SDS-PAGE and immunoblotting. The results indicated that, in vivo, OGE expressed keratin markers typical of differentiating mucosal epithelium; JE and REE, in contrast, lacked expression of most such markers but expressed keratins typical of simple epithelia together with some undefined keratin peptides. All epithelia showed changes in vitro but OGE remained different from JE and REE. OGE lost expression of the differentiation markers K1, K10 and K13; it acquired some expression of K19, but less than JE and REE. Cultures of JE and REE retained some expression of ICAM-1 and K8 and K18, and consistently acquired high levels of vimentin expression. These findings indicate that differences persist in standardized culture conditions and that these are apparently of an intrinsic nature. They support a concept of the origins of JE from REE and suggest that the unusual in vivo phenotype of JE results partly from intrinsic differences acquired during its development.
上皮细胞在表型表达模式上存在区域差异。将口腔黏膜与牙齿相连的结合上皮（JE）是一种独特的组织，其分化模式不同于其他口腔上皮，并且在无活力的牙齿表面形成基膜。建立这种异常表型的机制以及该上皮的发育起源均不确定。有人提出在牙齿萌出过程中，口腔牙龈上皮（OGE）向下生长形成JE，但形态学研究表明，它可能源自覆盖未萌出牙冠的缩余釉上皮（REE）。这些潜在起源的上皮在发育史上有所不同：因此它们之间的内在差异可能会显著影响由它们形成的上皮的表型。通过以下方法检测了解剖的JE、OGE和REE标本以及在标准化条件下培养的这些上皮细胞培养物的表型表达模式：（1）使用对个体细胞角蛋白、波形蛋白和细胞间黏附分子-1具有特异性的单克隆抗体进行免疫细胞化学检测；（2）通过二维SDS-PAGE和免疫印迹法检测。结果表明，在体内，OGE表达分化黏膜上皮典型的角蛋白标志物；相比之下，JE和REE缺乏大多数此类标志物的表达，但表达简单上皮典型的角蛋白以及一些未明确的角蛋白肽。所有上皮在体外均表现出变化，但OGE与JE和REE仍有所不同。OGE失去了分化标志物K1、K10和K13的表达；它获得了一些K19的表达，但低于JE和REE。JE和REE培养物保留了一些细胞间黏附分子-1以及K8和K18的表达，并持续获得高水平的波形蛋白表达。这些发现表明，在标准化培养条件下差异仍然存在，并且这些差异显然具有内在性质。它们支持JE起源于REE的概念，并表明JE在体内的异常表型部分源于其发育过程中获得的内在差异。
