MIGRATORY INTERACTION OF AMPHIBIAN EPIDERMAL-CELLS WITH COMPONENTS OFTHE BASEMENT-MEMBRANE

In adult newts, basal epidermal cells adjacent to a fresh wound move t oward the damaged area by migrating over the epidermal basement membra ne. In an attempt to determine which basement membrane components medi ate this migration, small pieces of glass coated with various natural matrices, purified proteins, or fragments of proteins were implanted i nto skin wounds such that epidermal cells attempting to form a wound e pithelium would encounter the implants. Laminin derived from a cell li ne (Ml 536-B3) that produces no type IV collagen was inactive as a mig ration substrate. Migration on recombinant entactin was somewhat bette r than on laminin but was still only approximately 14% of that on type I collagen. M15 matrix, a laminin and entactin-containing product of M1536-B3 cells, was no better than entactin alone. Type IV collagen wa s an excellent substrate, producing slightly more migration than corre sponding concentrations of type I collagen at nearly all concentration s tested. Migration on type IV lacking the NC1 domain was at least as good as on intact type IV. All the activity in type IV was present in a 95 kD fragment (alpha1(IV)95) from the carboxy terminal two-thirds o f the alpha1 chain. Approximately 60% of the activity on alpha1(IV)95 was obtained on implants coated with a 110 amino acid fragment of the alpha1 chain derived from the carboxy terminal half of alpha1(IV)95. A dding the synthetic peptide, arg-gly-asp-ser (RGDS) to the medium, blo cked migration on fibronectin-coated implants but had no effect on imp lants coated with type IV, suggesting that migration on type IV involv es different cell surface receptors than those mediating migration ove r fibronectin. Matrigel, a commercial product containing most basement membrane components, was a poor migration substrate. Thus if type IV mediates basal cell migration toward a wound in vivo, there may have t o be some alterations in basement membrane structure to allow epiderma l receptors to access type IV active site(s). (C) 1994 Wiley-Liss, Inc .