Mannose-receptor-mediated clearance of lysosomal alpha-mannosidase in scavenger endothelium of cod endocardium.
Mannose-receptor-mediated clearance of circulating glycoproteins was studied in Atlantic cod (Gadus morhua). Distribution studies with radioiodinated and fluorescently labelled ligands showed that cod liver lysosomal alpha-mannosidase and yeast invertase were rapidly eliminated from blood via a mannose specific pathway in liver parenchymal cells and endocardial endothelial cells of atrium and ventricle. Asialo-orosomucoid, a galactose-terminated glycoprotein, was cleared by liver only. In vitro studies were performed with primary cultures of atrial-endocardial endothelial cells (AEC), incubated at 12 degrees C in a serum free medium. Cod AEC endocytosed mannose-terminated glycoproteins (125I-alpha-mannosidase, 125I-invertase, 125I-mannan, 125I-ovalbumin and unlabelled lysosomal alpha-mannosidase), whereas 125I-asialo-orosomucoid was not recognised. Uptake of radiolabelled mannose-terminated ligands was inhibited 80-100% in the presence of excess amounts of mannan, invertase, D-mannose, L-fucose or EGTA. Our results suggest that the cod endocardial endothelial cells express a specific Ca(2+)-dependent mannose receptor, analogous to the mannose receptor on mammalian macrophages and liver sinusoidal endothelial cells.
Sørensen
K K
KK
The Norwegian School of Veterinary Science, Department of Arctic Veterinary Medicine, Tromso, Norway.
Tollersrud
O K
OK
Evjen
G
G
Smedsrød
B
B
D000818:Animals; D002478:Cells, Cultured; D004699:Endocardium / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D004727:Endothelium / Q000166:cytology / Q000378:metabolism; D005260:Female; D005399:Fishes / Q000502:physiology*; D006023:Glycoproteins / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000493:pharmacokinetics; D008247:Lysosomes / Q000378:metabolism*; D008297:Male; D008351:Mannans / Q000493:pharmacokinetics; D008361:Mannosidases / Q000302:isolation & purification / Q000378:metabolism*; D010047:Ovalbumin / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D014018:Tissue Distribution; D043323:alpha-Mannosidase; D043324:beta-Fructofuranosidase
D006023:Glycoproteins; D008351:Mannans; D017527:Receptor, IGF Type 2; D010047:Ovalbumin; D006026:Glycoside Hydrolases; D008361:Mannosidases; D043323:alpha-Mannosidase; D043324:beta-Fructofuranosidase