INTEGRIN RECEPTOR INVOLVEMENT IN ACTIN CABLE FORMATION IN AN IN-VITROMODEL OF EVENTS ASSOCIATED WITH WOUND CONTRACTION

Actin cables have been reported to act in vivo as contractile 'purse s trings' capable of closing embryonic wounds through generation of circ umferential tension. Furthermore, their involvement in wounds within i n vitro model systems suggests that actin cable contraction may be an important mechanism involved in the process of wound closure. The aim of this study therefore, was to investigate the appearance of actin ca bles in a contracting fibroblast populated collagen lattice, an in vit ro model of events associated with wound contraction. Utilising this i n vitro model, the time-course of actin cable production was investiga ted and the involvement of integrin receptors analysed using immunoflu orescent labelling techniques. Over a period of hours distinct cellula r cable-like structures developed at the edges of collagen lattices co inciding with the onset of contraction. Cellular organisation within t he cable was evident as was polymerisation of actin microfilaments int o elongated stress fibres forming a continuous cell-cell 'actin cable' around the circumference of the lattice. Immunolocalisation demonstra ted that integrin receptor subunit beta(1) and alpha(2) but not alpha( 5) were involved in apparent intimate cell-cell contact between juxtap osed fibroblasts within this actin cable. This study demonstrates the involvement of integrin receptors in actin cable formation within coll agen lattice systems undergoing reorganisation. Such integrin involvem ent may enable participating cells to respond to the tensional status of their surrounding environment and via cell-cell communication, to p ermit a co-ordinated contraction of the cable. It is concluded that in tegrin receptor involvement in active actin cable contraction may be i nvolved in the process of wound contraction. (C) 1997 Elsevier Science Ltd.