LAMININ-5 INHIBITS HUMAN KERATINOCYTE MIGRATION

Laminin-5 (previously known as kalinin, epiligrin, and nicein) is an a dhesive protein localized to the anchoring filaments within the lamina lucida space of the basement membrane zone lying between the epidermi s and dermis of human skin, Anchoring filaments are structures within the lamina lucida and lie immediately beneath the hemidesmosomes of th e overlying basal keratinocytes apposed to the basement membrane zone, Human keratinocytes synthesize and deposit laminin-5. Laminin-5 is pr esent at the wound edge during reepithelialization, In this study, we demonstrate that laminin-5, a powerful matrix attachment factor for ke ratinocytes, inhibits human keratinocyte migration. We found that the inhibitory effect of laminin-5 on keratinocyte motility can be reverse d by blocking the alpha 3 integrin receptor. Laminin-5 inhibits kerati nocyte motility driven by a collagen matrix in a concentration-depende nt fashion. Using antisense oligonucleotides to the alpha 3 chain of l aminin-5 and an antibody that inhibits the cell binding function of se creted laminin-5, we demonstrated that the endogenous laminin-5 secret ed by the keratinocyte also inhibits the keratinocyte's own migration on matrix. These findings explain the hypermotility that characterizes keratinocytes from patients who have forms of junctional epidermolysi s bullosa associated with defects in one of the genes encoding for lam inin-5 chains, resulting in low expression and/or functional inadequac y of laminin-5 in these patients. These studies also suggest that duri ng reepithelialization of human skin wounds, the secreted laminin-5 st abilizes the migrating keratinocyte to establish the new basement memb rane zone. (C) 1997 Academic Press.