1. Functional characterization of integrin alpha6beta4 adhesion interactions using soluble integrin constructs reveals the involvement of different functional domains in the beta4 subunit.
- Author
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Chen LL, Gabarra V, Cho S, Browning B, Cao X, Huet H, Cheung A, Morena R, Ramirez M, Shields M, Blake Pepinsky R, and McLachlan K
- Subjects
- Animals, Antibodies metabolism, CHO Cells, Cell Adhesion, Cell Communication, Cell Line, Tumor, Cricetinae, Cricetulus, Dimerization, Humans, Integrin beta4 immunology, Integrin beta4 physiology, K562 Cells, Keratinocytes cytology, Keratinocytes metabolism, Recombinant Fusion Proteins biosynthesis, Recombinant Fusion Proteins metabolism, Signal Transduction, Structure-Activity Relationship, Integrin alpha6beta4 physiology, Integrin beta4 chemistry
- Abstract
Integrin alpha6beta4-mediated adhesion interactions play key roles in keratinocyte and epithelial tumor cell biology. In order to evaluate how alpha6beta4 adhesion interactions contribute to these important cellular processes, the authors generated soluble versions of the integrin by recombinant expression of the subunit ectodomains fused to a human immunoglobulin G (IgG) Fc constant domain. Coexpression of the appropriate subunits enabled dimerization, secretion and purification of stable Fc-containing alpha6beta4 heterodimers. The soluble proteins exhibited the same metal ion and ligand dependency in their binding characteristics as intact alpha6beta4. Using these reagents in combination with anti-beta4 antibodies, the authors identified two distinct functional epitopes on the beta4 subunit. They demonstrated the involvement of one epitope in adhesion interactions and the other in regulating adhesion-independent growth in alpha6beta4-expressing tumor cell lines. The availability of these soluble integrin reagents and the data provided herein help to further delineate the structure-function relationships regulating alpha6beta4 signaling biology.
- Published
- 2008
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