Role of the integrin alpha v beta 6 in cell attachment to fibronectin. Heterologous expression of intact and secreted forms of the receptor.
The integrin alpha v beta 6 has been shown to be a fibronectin-binding protein. To determine whether the cytoplasmic and transmembrane domains of alpha v beta 6 are necessary for binding to fibronectin, a truncated, secreted form of the integrin lacking these domains was engineered and expressed in Chinese hamster ovary cells. Fibronectin affinity chromatography demonstrated that the secreted integrin, like its full-length counterpart, was capable of binding fibronectin. Monoclonal antibodies were made to secreted alpha v beta 6 and to beta 6-transfected NIH 3T3 cells. In experiments designed to determine whether alpha v beta 6 can mediate cell attachment to fibronectin, full-length human beta 6 was expressed in Chinese hamster ovary cells and in the human colon carcinoma cell line SW480. beta 6-expressing cells were identified by alpha v beta 6-specific antibodies, and the beta 6-transfectants were used in cell-adhesion assays. In Chinese hamster ovary cells, human beta 6 associated with hamster alpha v but was incapable of mediating cell attachment to fibronectin. However, expression of beta 6 in these cells had the dominant negative effect of decreasing alpha v beta 5-dependent adhesion to vitronectin. In SW480 cells, beta 6 expression conferred the ability to bind to fibronectin even in the presence of inhibitory antibodies against beta 1 integrins. In such cells, fibronectin binding ability could be blocked by an antibody to alpha v integrins. These results constitute the first direct evidence that alpha v beta 6 mediates cell attachment to fibronectin.
Weinacker
A
A
Lung Biology Center, University of California, San Francisco 94143.
Chen
A
A
Agrez
M
M
Cone
R I
RI
Nishimura
S
S
Wayner
E
E
Pytela
R
R
Sheppard
D
D
D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000951:Antigens, Neoplasm; D016466:CHO Cells; D002448:Cell Adhesion; D002460:Cell Line; D002846:Chromatography, Affinity; D006224:Cricetinae; D005353:Fibronectins / Q000378:metabolism*; D005434:Flow Cytometry; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D016023:Integrins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D008970:Molecular Weight; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D014162:Transfection
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D005353:Fibronectins; D016023:Integrins; D011994:Recombinant Proteins; C073878:integrin alphavbeta6