Identification and characterization of the T lymphocyte adhesion receptor for an alternative cell attachment domain (CS-1) in plasma fibronectin.
Using mAb technology (Wayner, E. A., W. G. Carter, R. Piotrowicz, and T. J. Kunicki. 1988. J. Cell Biol. 107:1881-1891), we have identified a new fibronectin receptor that is identical to the integrin receptor alpha 4 beta 1. mAbs P3E3, P4C2, and P4G9 recognized epitopes on the alpha 4 subunit and completely inhibited the adhesion of peripheral blood and cultured T lymphocytes to a 38-kD tryptic fragment of plasma fibronectin containing the carboxy-terminal Heparin II domain and part of the type III connecting segment (IIICS). The ligand in IIICS for alpha 4 beta 1 was the CS-1 region previously defined as an adhesion site for melanoma cells. The functionally defined mAbs to alpha 4 partially inhibited T lymphocyte adhesion to intact plasma fibronectin and had no effect on their attachment to an 80-kD tryptic fragment containing the RGD (arg-gly-asp) adhesion sequence. mAbs (P1D6 and P1F8) to the previously described fibronectin receptor, alpha 5 beta 1, completely inhibited T lymphocyte adhesion to the 80-kD fragment but had no effect on their attachment to the 38-kD fragment or to CS-1. Both alpha 4 beta 1 and alpha 5 beta 1 localized to focal adhesions when fibroblasts that express these receptors were grown on fibronectin-coated surfaces. These findings demonstrated a specific interaction of both receptors with fibronectin at focal contacts. In conclusion, these findings show clearly that cultured T lymphocytes use two independent receptors during attachment to fibronectin and that (a) alpha 5 beta 1 is the receptor for the RGD containing cell adhesion domain, and (b) alpha 4 beta 1 is the receptor for a carboxy-terminal cell adhesion region containing the Heparin II and IIICS domains. Furthermore, these data also show that T lymphocytes express a clear preference for a region of molecular heterogeneity in IIICS (CS-1) generated by alternative splicing of fibronectin pre-mRNA and that alpha 4 beta 1 is the receptor for this adhesion site.
Wayner
E A
EA
Fred Hutchinson Cancer Research Center, Seattle, Washington 98104.
Garcia-Pardo
A
A
Humphries
M J
MJ
McDonald
J A
JA
Carter
W G
WG
D000906:Antibodies; D000911:Antibodies, Monoclonal; D002448:Cell Adhesion; D002460:Cell Line; D005353:Fibronectins / Q000097:blood* / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*
D000906:Antibodies; D000911:Antibodies, Monoclonal; D005353:Fibronectins; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic