Carboxypeptidase Cathepsin X Mediates Beta2-integrin-dependent Adhesion of Differentiated U-937 Cells.
From: Faculty of Pharmacy, University of Ljubljana, Askerceva 7, SI-1000 Ljubljana, Slovenia.
Experimental cell research
- Publish Date: Aug 2006
- ISSN: 0014-4827
- Volume: 312
- Issue: 13
- Pages: 2515-27
- Medium: Print
- Language: English
- Citation (JAMA): Obermajer Natasa, Premzl Ales, Zavasnik Bergant Tina, et al. Carboxypeptidase Cathepsin X Mediates Beta2-integrin-dependent Adhesion of Differentiated U-937 Cells.. Exp. Cell Res. Aug 2006;312:2515-27
Abstract
Cathepsin X is a lysosomal carboxypeptidase with a potential role in processes of inflammation and immune response. The integrin-binding motifs RGD and ECD, present in the pro- and in mature forms of cathepsin X, respectively, suggest that this enzyme might have a function in cell signaling and adhesion. In this study, we report that cysteine protease inhibitors E-64 and CA-074 and 2F12 monoclonal antibody, all of which inhibit cathepsin X activity, significantly reduced adhesion of differentiated U-937 cells to polystyrene- and fibrinogen-coated surfaces via Mac-1 integrin receptor, whereas their binding to vitronectin, fibronectin or Matrigel was not affected. On the other hand, cathepsin X, added to differentiating U-937 cells, stimulated their adhesion. Using confocal microscopy, we demonstrated that the pro-form of cathepsin X was co-localized with beta(2) and beta(3) integrin subunits and its mature form solely with the beta(2) integrin subunit with the most intense signal in cell-cell junctions in differentiated U-937 cells and in co-cultures with endothelial cells. Our results indicate that active cathepsin X mediates the function of beta(2) integrin receptors during cell adhesion and that it could also be involved in other processes associated with beta(2) integrin receptors such as phagocytosis and T cell activation.
Mesh Headings (Keywords): Antibodies, Monoclonal, Antigens, CD18, Binding Sites, Carboxypeptidases, Cathepsins, Cell Adhesion, Cell Differentiation, Cysteine Proteinase Inhibitors, Dextrans, Endothelial Cells, Humans, Lactic Acid, Nanostructures, Phagocytosis, Polyglycolic Acid, Polymers, Protein Structure, Secondary, Protein Subunits, Protein Transport, U937 Cells, Vitronectin
Check for Full Text / PubMed Unique Identifier (PMID): 16774752
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