A mannose receptor mediates mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth muscle cells.
The putative mannose receptor (MR), previously implicated in mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth muscle (ASM) cells, was studied to determine its properties. Specific binding of the mitogenic neoglycoprotein, mannosylated bovine serum albumin (Man-BSA) to ASM cells was saturable, with an apparent Kd = 5.0 x 10(-8) M. Cell-bound ManBSA-colloidal gold conjugate was localized by electron microscopy to clathrin-coated pits on the cell surface, and was found to undergo internalization to endosomes; this was inhibitable by weak bases and swainsonine, that also inhibited ligand-induced mitogenesis. The ASM-MR, isolated by mannose-affinity chromatography, had the same apparent molecular mass as the macrophage (Mø) MR (M(r) = 175 kD), and was immunoprecipitated by an anti-MøMR immune serum. This antiserum blocked 125I-labeled-ManBSA binding to intact ASM cells, stimulated mitogenesis, and immunolocalized the ASM-MR in cytoplasmic vesicles compatible with endosomes. A monoclonal antibody directed against the MøMR also reacted with the ASM-MR; like the polyclonal antibodies, it stimulated mitogenesis as effectively as beta-hexosaminidases. These data indicate that the ASM-MR shares a number of functional and structural properties with the MøMR and suggest that similar receptors may have different main functions in different cells.
Lew
D B
DB
Crippled Children's Foundation Research Center, LeBonheur Children's Medical Center, Memphis, Tennessee.
Songu-Mize
E
E
Pontow
S E
SE
Stahl
P D
PD
Rattazzi
M C
MC
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002417:Cattle; D002455:Cell Division; D002478:Cells, Cultured; D006023:Glycoproteins / Q000494:pharmacology*; D037181:Lectins, C-Type; D008358:Mannose / Q000378:metabolism; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D009130:Muscle, Smooth / Q000166:cytology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000032:analysis / Q000502:physiology*; D012709:Serum Albumin / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014132:Trachea / Q000166:cytology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D012709:Serum Albumin; C023840:mannose-bovine serum albumin conjugate; D008358:Mannose; D013936:Thymidine