
pmid: 15220135
Abstract Vascular cell adhesion molecule (VCAM)-1 supports specific eosinophil adhesion via α4β1 integrin. We tested the hypothesis that adhesive contacts formed by eosinophils on VCAM-1 are different from focal adhesions formed by adherent fibroblasts. Eosinophils adherent on VCAM-1 formed punctate adhesions that fit the criteria for podosomes, highly dynamic structures found in adherent transformed fibroblasts, osteoclasts, and macrophages. The structures contained β1 integrin subunit, phosphotyrosine-containing proteins, punctate filamentous actin, and gelsolin, a podosome marker. In contrast, nontransformed fibroblasts on VCAM-1 formed peripheral focal adhesions that were positive for α4, β1, phosphotyrosine, vinculin, talin, and paxillin; negative for gelsolin; and associated with microfilaments. Phorbol myristate acetate or tumor necrosis factor-α and interleukin-5 stimulated podosome formation in adherent eosinophils. Because podosomes in tumor cells are associated with extracellular matrix degradation, we analyzed the VCAM-1 layer. VCAM-1 was lost under adherent eosinophils but not under adherent fibroblasts. This loss was inhibited by the metalloproteinase inhibitor ortho-phenanthroline and correlated with expression and podosome localization of a membrane-tethered metalloproteinase, a disintegrin and metalloproteinase domain 8. Podosome-mediated VCAM-1 clearance may be a mechanism to regulate eosinophil arrest and extravasation in allergic conditions such as asthma.
Disintegrins, Macrophages, Osteoclasts, Fibroblasts, Integrin alpha4beta1, Phosphoproteins, Cell Membrane Structures, Actins, Asthma, Eosinophils, Actin Cytoskeleton, Cytoskeletal Proteins, Matrix Metalloproteinase 8, Cell Adhesion, Humans, Interleukin-5, Paxillin, Phosphotyrosine, Gelsolin, Phenanthrolines
Disintegrins, Macrophages, Osteoclasts, Fibroblasts, Integrin alpha4beta1, Phosphoproteins, Cell Membrane Structures, Actins, Asthma, Eosinophils, Actin Cytoskeleton, Cytoskeletal Proteins, Matrix Metalloproteinase 8, Cell Adhesion, Humans, Interleukin-5, Paxillin, Phosphotyrosine, Gelsolin, Phenanthrolines
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