Adhesion and migration of avian neural crest cells on fibronectin require the cooperating activities of multiple integrins of the beta 1 and beta 3 families

Based on genetic, functional and histological studies, the extracellular ma trix molecule fibronectin has been proposed to play a key role in the migra tion of neural crest cells in the vertebrate embryo. In the present study, we have analyzed in vitro the repertoire and function of integrin receptors involved in the adhesive and locomotory responses of avian truncal neural crest cells to fibronectin. Immunoprecipitation experiments showed that neu ral crest cells express multiple integrins, namely alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1, alpha 8 beta 1, alpha v beta 1 alpha v beta 3 and a beta 8 integrin, as potential fibronectin receptors, and flow cytometry an alyses revealed no major heterogeneity among the cell population for expres sion of integrin subunits, In addition, the integrin repertoire expressed b y neural crest cells was found neat to, change dramatically during migratio n, At the cellular level, only alpha v beta 1 and alpha v beta 3 were conce ntrated in focal adhesion sites in connection with the actin microfilaments , whereas the other integrins were predominantly diffuse over the cell surf ace, In inhibition assays with function-perturbing antibodies, it appeared that complete abolition of cell spreading and migration could be achieved o nly by blocking multiple integrins of the beta 1 and beta 3 families, sugge sting possible functional compensations between different integrins, In add ition, these studies provided evidence for functional partitioning of integ rins in cell adhesion and migration, While spreading was essentially mediat ed by alpha v beta 1 and alpha 8 beta 1, migration involved primarily alpha 4 beta 1, alpha v beta 3 and alpha 8 beta 1 and, more indirectly, alpha 3 beta 1, alpha 5 beta 1 and the beta 8 integrin were not found to play any m ajor role in either adhesion or migration, Finally, consistent with the res ults of inhibition experiments, recruitment of alpha 4 beta 1 and alpha v b eta 3, individually or in combination using antibodies or recombinant VCAM- 1 and PECAM-1 molecules as a substratum, was required for migration but was not sufficient to produce migration of the cell population as efficiently as with fibronectin, In conclusion, our study indicates that neural crest c ells express a multiplicity of fibronectin-binding integrins and suggests t hat dispersion of the cell population requires cooperation between distinct integrins regulating different events of cell adhesion, locomotion and, po ssibly, proliferation and survival.