Adherens Junctions: Demonstration in Human Epidermis

Abstract

Adherens junctions are intercellular and cell-matrix junctions that, like desmosomes and hemidesmosomes, mediate adhesion of cells to each other or to matrix structures. These junctions have been detected recently in cultured human keratinocytes, indicating that they may be of importance in epidermis. To investigate the localization of adherens junctions in normal epidermis, we examined human epidermis, human oral mucosa, and monkey esophagus for the presence of vinculin, a major protein of the intracellular plaques of adherens junctions that is thought to be present in all adherens junctions. Western blot analysis demonstrated vinculin in extracts of epidermis. Immunohistochemistry of vinculin in these tissues displayed two distinct locations for adherens junctions: i) at the dermal-epidermal junction, and ii) in the region of cell-cell contacts in all layers of the epidermis. The location of vinculin in the region of the epidermal-dermal junction is reminiscent of the distribution of vinculin-containing focal contacts in cultured keratinocytes, and the intercellular staining of vinculin in epidermis is consistent with the presence of vinculin in adherens junctions in cultured keratinocytes at sites of cell-cell contact. These results demonstrate that adherens junctions are present in human epidermis, oral mucosa, and monkey esophagus. Vinculin-containing junctions in epidermis may be important in the pathogenesis of skin diseases involving alterations in intercellular integrity.