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 alpha E beta 4 (also called alpha 6 beta 4) and alpha 2 beta 1. The alpha E beta 4 integrin is localized at the surface of basal cells in contact with the basement membrane, whereas alpha 2 beta 1/alpha 3 beta 1 integrins are absent from the basal surface and are localized only on the lateral surface of basal and spinous keratinocytes. Anti-beta 4 antibodies potently inhibited keratinocyte adhesion to matrigel or purified laminin, whereas anti-beta 1 antibodies were ineffective. Only anti-beta 4 antibodies were able to detach established keratinocyte colonies. These data suggest that alpha E beta 4 mediates keratinocyte adhesion to basal lamina, whereas the beta 1 subfamily is involved in cell-cell adhesion of keratinocytes.