Efficient uptake of mannosylated proteins by a human Schwann cell line.
Complex carbohydrate structures are essential molecules of infectious microbes and host cells, and are involved in cell signaling associated with inflammatory and immune responses. The uptake of mannose-tailed glycans is usually carried out by macrophages, dendritic cells (DCs), and other professional phagocytes to trigger MHC class I- and MHC class II-restricted antigen presentation, and to promote T cell effector responses. Since Schwann cells (SCs) have been proposed as immunocompetent cells, we investigated whether a human cell line (ST88-14 cells) could bind mannosylated ligands in a specific manner. The saturation of uptake of mannosylated molecules by ST88-14 cells and the internalization and distribution pathway of these ligands were tested by cytometry and confocal plus electron microscopy, respectively. This uptake showed a dose-dependent increase, the saturation point being reached at high concentrations of mannosyl residues/240 mM mannose. Merging of man/BSA-FITC and S100 labeling showed their partial, but, significant colocalization. Ultrastructural analysis of ST88-14 cells after incubation with HRP-colloidal gold, without or with subsequent chasing at 37C, showed an initial location on the cell surface and temperature- and time-dependent internalization of the probe. Our findings suggest an efficient mannosylated ligand uptake system through putative lectin(s) that may be operational in inflammatory and immune responses.
Baetas-da-Cruz
Wagner
W
Federal University of Rio de Janeiro, Institute of Biophysics Carlos Chagas Filho, Laboratory of Developmental Neurobiology, Rio de Janeiro, Brazil.
Alves
Lucinéia
L
Guimarães
Erick V
EV
Santos-Silva
Alessandra
A
Pessolani
Maria Cristina V
MC
Barbosa
Helene S
HS
Corte-Real
Suzana
S
Cavalcante
Leny A
LA
D045744:Cell Line, Tumor; D004705:Endocytosis / Q000276:immunology; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006046:Gold / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D037181:Lectins, C-Type / Q000378:metabolism / Q000648:ultrastructure; D008024:Ligands; D008358:Mannose / Q000378:metabolism*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism / Q000648:ultrastructure; D011956:Receptors, Cell Surface / Q000378:metabolism / Q000648:ultrastructure; D009418:S100 Proteins / Q000378:metabolism; D012583:Schwann Cells / Q000378:metabolism* / Q000648:ultrastructure
D005456:Fluorescent Dyes; D037181:Lectins, C-Type; D008024:Ligands; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D009418:S100 Proteins; D006046:Gold; D006735:Horseradish Peroxidase; D016650:Fluorescein-5-isothiocyanate; D008358:Mannose