Synthesis and expression of the fibroblast fibronectin receptor in human monocytes.

Abstract

Human monocytes adhere to fibronectin, but the receptor (or receptors) mediating this interaction has not been clearly identified. To examine the nature of this receptor, human monocytes were obtained by counter-current elutriation and were found to adhere to immobilized fibronectin but not to vitronectin or von Willebrand factor. Antibodies and peptides were used to determine whether monocyte adherence to immobilized fibronectin was mediated by a receptor similar to that which mediates the adherence of fibroblasts to fibronectin. Antibodies against both the a and ft subunits of the fibroblast fibronectin receptor (VLA-5) inhibited monocyte adherence to fibronectin. These antibodies immunoprecipitated two surface proteins from monocytes that migrated at 140 and 120 kD under nonreducing conditions. Surface proteins with identical apparent molecular weights were immunoprecipitated from surfacelabeled MG-63 cells, a fibroblast-like cell line. A synthetic peptide containing the Arg-Gly-Asp-Ser (RGDS) sequence also inhibited monocyte adherence to fibronectin. cDNA hybridization experiments revealed the presence of mRNA for both the a and ft subunits of the fibroblast fibronectin receptor in human monocytes. We conclude that circulating monocytes express a fibronectin receptor that is structurally and functionally very similar, if not identical, to the fibronectin receptor in adherent fibroblasts, and that this receptor mediates monocyte adherence to immobilized fibronectin.

Vascular cell adhesion molecule-1 and the integrin VLA-4 mediate adhesion of human B cell precursors to cultured bone marrow adherent cells.

“…The CD49e antibody used (BIIG2) was used at a concentration demonstrated to show blocking ofVLA-5 dependent adhesion (21). FN-40 was used at a concentration (100 ug/ml) shown to inhibit binding of VLA-4-positive cells to FN-40-coated plates by 90% (24).…”

LeishmaniaInfection Impairs β1-Integrin Function and Chemokine Receptor Expression in Mononuclear Phagocytes

“…Integrins ␣ 4 /␤ 1 (VLA4) and ␣ 5 /␤ 1 (VLA5) are important in the interaction of monocytes with fibronectin (5,10,49). We have previously shown that monocytic phagocytes rely mainly on ␤ 2 -and ␣ 4 -integrins to adhere to the inflamed connective tissue (11).…”

Coexpression of two fibronectin receptors, VLA-4 and VLA-5, by immature human erythroblastic precursor cells.

“…Cell distribution for each one of these integrins shows a clearly distinct pattern. Thus, VLA-5 is widely distributed (5,8,16), whereas the expression of VLA-3 and VLA-4 is more restricted, the first to adherent cells such as fibroblasts and epithelial cells (5,17), and the second to peripheral blood cells of the monocytic and lymphoid lineages as well as related cell lines (13,16,18).…”