Role of the integrin alpha v beta 6 in cell attachment to fibronectin. Heterologous expression of intact and secreted forms of the receptor

• Published in: The Journal of biological chemistry 1994-03, Vol.269 (9), p.6940-6948
• Main Authors: Weinacker, A, Chen, A, Agrez, M, Cone, R I, Nishimura, S, Wayner, E, Pytela, R, Sheppard, D
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Animals; Antibodies, Monoclonal - pharmacology; Antigens, Neoplasm; Cell Adhesion; Cell Line; CHO Cells; Chromatography, Affinity; Cricetinae; Fibronectins - metabolism; Flow Cytometry; Gene Expression; HeLa Cells; Humans; Integrins - biosynthesis; Integrins - isolation & purification; Integrins - metabolism; Mice; Mice, Inbred BALB C - immunology; Molecular Weight; Plasmids; Recombinant Proteins - biosynthesis; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(17)37465-3

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.