A study of the structure, function and distribution of β5 integrins using novel anti-β5 monoclonal antibodies

Abstract

Here, we have utilized six new anti-human beta 5 monoclonal antibodies to perform a detailed investigation of the structure, function and distribution of beta 5 integrins. Monoclonal anti-beta 5 specificity was confirmed by reactivity with beta 5-transfected CHO cells, by direct binding to the beta 5 subunit (immunoblotting), and by immunodepletion experiments using polyclonal anti-beta 5 serum. The beta 5 subunit was predominantly associated with the alpha v subunit, although on some cell lines, the level of beta 5 exceeded that of alpha v for unknown reasons. Cell adhesion studies showed that the adhesive function of beta 5 could be stimulated, inhibited or unaltered by different anti-beta 5 monoclonal antibodies. The beta 5 subunit was involved in adhesion to both vitronectin and fibronectin and, at least for K562 cells, fibronectin appeared to be the preferred ligand. Flow-cytometry studies showed that the beta 5 subunit was expressed at moderate to high levels on all adherent cell lines examined, was absent from all lymphoid cell lines, and was only weakly expressed on myeloid cell lines. Staining of thymic sections showed the distribution of beta 5 on blood vessels, Hassal's corpuscles, cortical and medullary stromal cells, and basement membranes. Skin sections showed beta 5 on the basal layer of the epidermis and on some dermal blood vessel walls, and kidney sections showed staining of glomerular regions, juxta glomerular apparatus, proximal convoluted tubules and collecting tubules, and at least one anti-beta 5 antibody also stained epithelial cells of proximal tubules.

Functional Analyses of Two Cellular Binding Domains of Bovine Lactadherin

“…The present results demonstrate that bovine lactadherin can function as an effective extracellular matrix for the adhesion of cells containing the α v β 3 and α v β 5 integrin receptors. Expression of the α v β 3 integrin seems to be confined to a smaller number of cell types primarily proliferating endothelial cells (), whereas the α v β 5 integrin receptor is expressed in a number of different tissues ( , ) and the pattern is similar to that of lactadherin ().…”

Bovine PAS-6/7 Binds αVβ5 Integrin and Anionic Phospholipids through Two Domains

“…Since the R V β 5 integrin is found in a wide variety of tissues (Cheresh et al, 1989;Pasqualini et al, 1993;Gui et al, 1995), it was interesting to investigate the tissue distribution of glycoprotein PAS-6/7 as well. Originally, PAS-6/7 was described as an MFGM protein; however, nonlactating udder samples showed the same level of PAS-6/7 as the lactating udder.…”

“…Interestingly, PAS-6/7 was not detected in plasma and preparations of erythrocyte ghosts. The R V β 5 integrin has been reported to have been present in the blood vessel wall (Pasqualini et al, 1993), and it is tempting to speculate that the plasma is depleted for PAS-6/7 by binding to this integrin. Nevertheless, the plasma level of human BA46 has been found useful as a breast cancer maker, since it is overexpressed by breast cancer cells, resulting in an elevated level of BA46 in the blood (Salinas et al, 1987;Larocca et al, 1991).…”

Novel and Selective αvβ3 Receptor Peptide Antagonist: Design, Synthesis, and Biological Behavior

“…Conversely, tumor cells expressing α v β 5 integrin require a tyrosine kinase receptor-mediated signaling event for motility on vitronectin and in vivo dissemination . Although α v β 5 is widely expressed by many malignant tumor cells, α v β 3 has a relatively limited cellular distribution compared with that of α v β 5 . , Therefore, to target α v β 3 -mediated processes for diagnostic or therapeutic purposes, the development of new compounds that can discriminate between α v β 3 and α v β 5 is required.…”