Keratinocyte growth factor (KGF) promotes keratinocyte cell attachment and migration on collagen and fibronectin

Abstract

Keratinocyte growth factor (KGF) induction of keratinocyte attachment and migration on provisional and basement membrane proteins was examined. KGF-treated keratinocytes showed increased attachment to collagen types I and IV and fibronectin, but, not to laminin-1, vitronectin, or tenascin. This increase was time- and dose-dependent. Increase in attachment occurred with 2-10 μg/ml of ECM proteins. This KGF-stimulated cell attachment was β1 integrin-dependent but was not associated with stimulation of the cell surface expression nor affinity (activity) of the collagen integrin receptor (α2β1) nor the fibronectin integrin receptors (α5β1 or αv). At the basal layer of KGF-treated cells significant accumulation of β1 integrins was found at the leading edges, and actin stress fibers colocalized with β1. KGF also induced migratory phenotype and stimulated keratinocyte migration on both fibronectin and collagen types I and IV but not on laminin-1, vitronectin nor tenascin. The results suggest that in addition to its proliferation promoting activity, KGF is able to modulate keratinocyte adhesion and migration on collagen and fibronectin. Our data suggest that KGF induced integrin avidity (clustering), a signaling event, which is not dependent on the alteration of cell surface integrin numbers.