Keratinocyte motility induced by TGF‐β1 is accompanied by dramatic changes in cellular interactions with laminin 5

Abstract

Transforming growth factor‐β1 (TGF‐β1) has the ability to induce epithelial cell migration while stopping proliferation. In this study, we show that, concomitant to promoting migration of normal human keratinocytes in vitro, TGF‐β1 induced a marked decrease in their adhesion capacity to processed α3‐containing laminin 5‐coated surfaces. Indeed, the expression levels of α3 and α6 integrin subunit mRNA and protein, as well as the cell surface α3β1 and α6β4 integrins, were down‐regulated. Recent studies showed that keratinocytes over express and deposit laminin 5 during migration and we have shown that laminin 5 found in the matrix of TGF‐β1 induced migrating keratinocytes is present in its unprocessed form [Décline and Rousselle, 2001: J. Cell Sci. 114:811–823]. We show here that TGF‐β1 treatment of the cells promoted a significant increase in their adhesion to the α3 chain carboxy‐terminal LG4/5 subdomain and that this interaction is likely to be mediated by a heparan sulfate proteoglycan type of receptor. Our results indicate that α6β4 and α3β1 integrin interactions with laminin 5 are diminished during migration while a specific interaction occurs between an additional cellular receptor and the α3 LG4/5 module present on unprocessed laminin 5. Cell Motil. Cytoskeleton 54:64–80, 2003.