α7 Integrin Mediates Cell Adhesion and Migration on Specific Laminin Isoforms*
- From the Departments of Stomatology and Anatomy, Schools of Dentistry and Medicine, University of California San Francisco, San Francisco, California 94143-0512
- ‡ To whom correspondence should be addressed: University of California at San Francisco, Departments of Stomatology and Anatomy, Box 0512, San Francisco, CA 94143-0512. Tel.: 415-476-3275; Fax: 415-476-4204; E-mail: randyk{at}itsa.ucsf.edu
Abstract
The laminin-binding α7β1 integrin receptor is expressed at high levels by skeletal and cardiac muscles and by certain melanocytic cells. We have assessed the potential role of the α7A/B integrin isoforms in mediating cell adhesion and motility and determined the laminin isoform specificity of this integrin. When MCF-7 breast carcinoma cells, normally nonadherent to laminin 1, were stably transfected with cDNA for mouse α7, they adhered with high efficiency and migrated on laminin 1 substrates. Function-perturbing monoclonal antibodies generated to mouse α7 subunit blocked both adhesion and migration of α7 transfectants on laminin 1 substrates. Additional studies with MCF-7 transfectants revealed that α7β1 binds well to laminin 1 and to a mixture of laminin 2 and 4 but not to laminin 5. Importantly, α7β1 was capable of promoting motility on both laminin 1 and laminin 2/4 substrates. However, MCF-7 cells transfected with cDNA for either α7A or α7B showed no significant differences in cell adhesion or motility on laminin 1 substrates. Although the role for the alternatively spliced cytoplasmic variants of α7 remains unknown, the results establish that α7β1 mediates cell adhesive activities on a restricted number of laminin isoforms.
Footnotes
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↵* This work was supported by National Institutes of Health Grants R01 CA33834 and R01 DE10306. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- mAb
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monoclonal antibody
- PBS
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phosphate-buffered saline
- BSA
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bovine serum albumin.
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↵2 C. Yao and R. H. Kramer, manuscript in preparation.
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↵3 C. Lin and R. H. Kramer, manuscript in preparation.
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- Received March 26, 1996.
- Revision received July 8, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
