ABSTRACT

One of the fundamental functions of epithelial tissues, such as the epidermis, is separation and thus protection of the underlying tissues from the potentially hostile ‘‘environment.’’ To assist in such a role, a sophisticated network of cell-cell junctions has been developed by the epidermal cells, keeping them close together and coordinating their behavior. Intercellular junctions are classically subdivided into (i) communication junctions, allowing direct connection between cytosols of adjacent interacting cells; (ii) mechanical junctions, establishing intercellular connections stabilized by actin or keratin cytoskeletons; and (iii) tight junctions, which seal off paracellular transport within the epithelia. Regardless of the primary function of any type of junction, all the cell-cell contacts are involved in some sort of transmission or perception of the information which helps each cell to ‘‘keep in touch’’ with the others, within the same epithelium, both literally and metaphorically.