Proteolitic Activity Of Jararhagin Stimulates Fak Phosphorylation And The Recruitment Of Specific Integrins To Focal Contacts.

Costa; E.P. & Santos, M.F. 

Depto. Histology and Embriology, ICB/USP-05508-000.

Objectives: Jararhagin (JG) is a toxin from the venom of Bothropsjararaca that has different domains such as the metalloprotease and disintegrin. In this study we investigated the effects of Jararhagin on epithelial cell adhesion and migration in vitro, using an epithelial restitution experimental model.

Methods and results: F-actin arrangement and the distribution of laminin, fibronectin, several integrins and phosphorylated FAK were studied using rodhamine-plalloidin and immunofluorescence. Maximum stimulation of migration (about 100%) was obtained with 5 mg/ml JG, with about 38% inhibition of cellular adhesion. In migratory cells the toxin stimulated the formation of filopodia, lamellipodia  and stress fibers. The pericellular fibronectin matrix was lost in migrating cells, while laminin was less affected. The toxin stimulated FAK phosphorylation and the recruitment of av-containing integrins to focal contacts, whereas integrins containing the a2 subunit were reduced in these junctions. Inactivation of the toxin with 1,10 phenantroline showed that the catalytic activity is important for the effect of Jararhagin on cell migration, FAK phosphorylation and for the recruitment of av, but not as much for the anti-adhesive effect.

Conclusion: Jararhagin stimulates the migration of epithelial cells in vitro through a mechanism that involves its proteolytic activity, qualitative changes in cellular adhesion and the formation of actin-rich cellular processes.

Financial support : FAPESP, CNPq.

Correspondence to:  epcosta@usp.br or mfsantos@usp.br