Polarized Integrin Mediates Human Keratinocyte Adhesion to Basal Lamina

Epithelial cell interactions with matrices are critical to tissue organization. Indirect immunofluorescence and immunoprecipitations of cell lysates prepared from stratified cultures of human epidermal cells showed that the major integrins expressed by keratinocytes are αEβ4(also called α6β4) and α2β1/α3β1. The αEβ4integrin is localized at the surface of basal cells in contact with the basement membrane, whereas α2β1/ α3β1integrins are absent from the basal surface and are localized only on the lateral surface of basal and spinous keratinocytes. Anti-β4antibodies potently inhibited keratinocyte adhesion to matrigel or purified laminin, whereas anti-β1antibodies were ineffective. Only anti-β4antibodies were able to detach established keratinocyte colonies. These data suggest that αEβ4mediates keratinocyte adhesion to basal lamina, whereas the β1subfamily is involved in cell-cell adhesion of keratinocytes.