HUMAN KERATINOCYTE MIGRATION ON TYPE-IV COLLAGEN - ROLES OF HEPARIN-BINDING SITE AND ALPHA-2-BETA-1 INTEGRIN

BACKGROUND: The migration of human keratinocytes is an early and important event in the reepithelialization of cutaneous wounds. Type IV collagen, a ubiquitous basement membrane component, promotes keratinocyte migration. EXPERIMENTAL DESIGN: In this study, we sought to identify specific sites within the type IV collagen molecule that induce keratinocyte locomotion and to characterize the cell surface receptors involved. We first examined purified fragments of the type IV collagen molecule as substrates for keratinocytes in a phagokinetic migration assay. We then tested several synthetic peptides derived from the triple-helical region of type IV collagen, as well as antibodies against specific integrin subunits, for their ability to either support or inhibit keratinocyte migration on matrices of both type IV collagen and relevant peptide derivatives. RESULTS: Keratinocytes migrated on the triple-helical fragment to the same extent as they did on the native type IV collagen. The amino-terminal 7S and the carboxy-terminal NC1 regions of type IV collagen failed to support keratinocyte migration. In addition, Hep III peptide was active both in inhibiting keratinocyte migration on type IV collagen and in serving as a substrate matrix for migration. Peptide containing the amino acid sequence RGD did not influence cell migration on type IV collagen. A specific monoclonal antibody against the alpha 2 beta 1 integrin receptor significantly inhibited keratinocyte migration on matrices of both type IV collagen and Hep III peptide. CONCLUSIONS: Keratinocyte migration on type IV collagen involves the interaction of the alpha 2 beta 1 receptor with the Hep III region of the type IV collagen molecule.