Keratinocyte migration requires alpha 2 beta 1 integrin-mediated interaction with the laminin 5 gamma 2 chain

Keratinocyte migration is an absolute requirement for correct epithelializa tion during the process of wound healing. This process requires changes in extracellular matrix ligand expression as well as changes in ligand-binding affinity of the corresponding cellular integrins. In this study, we attemp t to understand the role of laminin 5 in migration by investigating the int egrin-mediated interactions of migrating keratinocytes with their newly syn thesized laminin 5. We chose to induce migration of freshly isolated NHK in vitro by exposing them to TGF-beta1 which, in addition to promoting epithe lial cell migration, is also known to prevent cell proliferation. This impo rtant feature allowed the study to be focused on cell migration without int erfering with cell proliferation. We confirm that keratinocyte migration on plastic, fibronectin or collagen IV substrates requires endogenous laminin 5 deposition, which is predominantly detected under its unprocessed form. Despite a crucial role for laminin 5 in migration, we show that this proces s is accompanied by a significant decrease in adhesion to purified laminin 5. Moreover, we provide evidence that the alpha3 beta1 integrin interaction with newly synthesized laminin 5 renders the cells more adherent and retar ds migration. Conversely, we provide evidence that the alpha2 beta1 integri n-laminin 5 interaction is absolutely required for keratinocyte migration a nd that the alpha2 beta1 integrin is responsible for cell spreading on lami nin 5. Finally, we demonstrate that the alpha2 beta1 integrin binding to la minin 5 occurs within the short arm of the gamma2 subunit.