Hyaluronan-binding proteins on cultured J 774 macrophages.
Cultivated macrophages of murine cell-line J 774 were found to bind high-molecular-weight (molecular weight average approx. 5.10(6) [3H]hyaluronan (HA) by a saturable mechanism at 4 degrees C. Half-maximal binding was observed at 7-8 microgram/ml (1.4-1.6 nM) and the maximal binding was reached at 30-40 microgram/ml. Scatchard plot analysis revealed that approx. 20,000 molecules could bind to each cell with a Kd of 1.5 nM. The binding could be effectively inhibited by unlabeled HA. Also chondroitin sulphate inhibited the binding, but only to about 50%. At 37 degrees C the J 774 cells took up and degraded the polysaccharide effectively. Affinity chromatography on HA coupled to agarose of solubilized surface-iodinated J 774 cells, revealed that a protein of approx. 60 kDa, when analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis and autoradiography, could be specifically eluted with HA-oligosaccharides. Our results suggest that J 774 macrophages can bind HA by a mechanism compatible with receptor-binding, and carry a 60 kDa HA-binding protein on their surface. This receptor-binding may mediate uptake and degradation of the polysaccharide and influence the levels and turnover of HA in interstitial fluid as well as the release of HA into the bloodstream.
Gustafson
S
S
Department of Medical and Physiological Chemistry, University of Uppsala, Sweden.
Forsberg
N
N
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008264:Macrophages / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D013696:Temperature
D002352:Carrier Proteins; D018960:Hyaluronan Receptors; D007457:Iodine Radioisotopes; D008565:Membrane Proteins; D006820:Hyaluronic Acid