VLA-5 in the plasma cell line, FR4ds, acts as a common regulator of VLA-4 and VLA-6 in spreading induced by fibronectin and laminin.

VLA-B recognizes the GRGDSP sequence of fibronectin (FN) in the extracellular matrix (ECM). We examined the role of beta 1 integrin in the spreading of the human plasma cell line, FR4ds, induced by FN and laminin (LN). We first examined the role of VLA-5 in the spreading induced by FN. Anti-alpha 4 antibody induced 46.4% inhibition, whereas anti-alpha 5 had no effect. A combination of anti-alpha 4 and anti-alpha 5 enhanced the inhibition of spreading significantly, Complementary inhibition was also demonstrated using the GRGDSP peptide plus anti-alpha 4 and the GRGDNP peptide of LN plus anti-alpha 4. The results suggested that VLA-5 is a regulator of VLA-4 and that it is involved in the recognition of CRGDNP. We then examined the role of VLA-5 in the spreading induced by LN. Anti-alpha 6 induced 53.1% inhibition. Anti-alpha 5 alone had no effect. A combination of alpha 5 and anti-alpha 6, however, significantly enhanced the inhibition of spreading. The combination of GRGDSP plus anti-alpha 6 and GRGDNP plus anti-alpha 6 resulted in complete inhibition. These results suggested that VLA-5 participates in the recognition of LN cooperatively with VLA-6 and that VLA-5 is a common regulator of VLA-4 and the LN receptor, VLA-6. (C) 1996 Academic Press, Inc.