β1 integrins do not have a major role in keratinocyte intercellular adhesion

Abstract

Integrins of the epidermis have been implicated both in intercellular adhesion and in cell-substratum adhesion. In the present study the role of α2β1 and α3β1 integrins has been evaluated further using human keratinocyte culture. α3β1 but not α2β1 strongly colocalizes with talin in adhesion plaques, consistent with a role forthe former in adhesion to endogenous matrix. Uponelevation of the extracellular Ca2+ concentration from 30 μM to 1.0 mM, which isknown to induce the organization of intercellular junctions, all three integrin subunits redistribute to concentrate along the cell-cell borders, but α3 redistributes more slowly. Blocking antibody to E-cadherin, which has previously been shown to delay the establishment of cell-cell adhesion upon Ca2+ elevation, delays theredistribution of α2β1 and α3β1 integrins. Elevation of the Ca2+ concentration also induces a rapid morphological change in the keratinocytes and organization of the culture into colonies with tight cell-cell connections. Blocking antibodies to β1 or to α3, but not to α2, delays this morphological change and the organization into colonies; however, the effect is much more pronounced in subconfluent cultures. These data are consistent with the hypothesis that anti-β1 or anti-α3 antibodies affect cell-cell interactions primarily through their previously described inhibition of motility. Stratification of the culture, which follows the formation of intercellular interactions, is normal in the presence ofblocking antibody to α1 integrin. In summary, these data suggest that integrins do not playa major role in intercellular keratinocyte adhesion, but may appear to do so under certain conditions because of their involvement in motility. © 1995 Academic Press, Inc.