α5β1 integrin mediates cell adhesion to extracellular matrix by interacting with fibronectin (FN). Mouse lines carrying null mutations in genes encoding either the α5 integrin subunit or FN have been generated previously. Both mutations are embryonic lethal with overlapping defects, but the defects of α5-null embryos are less severe. Primary embryonic cells lacking α5β1 are able to adhere to FN, form focal contacts, migrate on FN, and assemble FN matrix. These results suggest the involvement of (an)other FN receptor(s). In this study, we examined functions of α4β1 and α(v) integrins in embryonic cells lacking α5β1. Our analysis of cells lacking both α4β1 and α5β1 showed that α4β1 is also not required for these FN-dependent functions. Using α(v)-specific blocking reagents, we showed that α(v) integrins are required for α5-null cells, but not wild-type cells, to adhere and spread on FN. Our data also showed that, although the expression levels of α(v) integrins on the wild-type and α5-null cells are similar, there is an increase in recruitment of α(v) integrins into focal contacts in α5-null cells plated on FN, indicating that α(v) integrins can compensate functionally for the loss of α5β1 in focal contacts of α5-null cells. Finally, our data suggested possible roles for α(v) integrins in replacing the role of α5β1 in FN matrix assembly in vitro and in FN-dependent embryonic functions in vivo.
|Original language||English (US)|
|Number of pages||12|
|Journal||Molecular Biology of the Cell|
|State||Published - Nov 1996|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology