The endocytic pathway for H-ferritin established in live MOLT-4 cells by laser scanning confocal microscopy.
We have established the intracellular destination of the putative immunoregulatory protein, human recombinant H (heavy)-ferritin, in the transformed T-cell line MOLT-4, by laser scanning confocal microscopy of live cells. A series of confocal images was collected over a 60 min time course using indirect immunofluorescence of H-ferritin and transferrin, their respective monoclonal antibodies, and fluorescein isothiocyanate (FITC)-labelled IgG. A marked drop in FITC fluorescence after 40 min of H-ferritin internalization, indicative of an acidic environment, and co-localization with tetramethylrhodamine isothiocyanate-labelled-dextran strongly suggests that H-ferritin is transferred to the lysosome. In contrast, transferrin was observed to return to the cell surface. Electron microscopy confirmed that H-ferritin was transferred to the lysosome. The receptor-mediated endocytosis and lysosomal delivery of H-ferritin may thus potentiate its putative immunoregulatory activity.
Moss
D
D
Liver Unit, Queensland Institute of Medical Research, Brisbane, Australia.
Hibbs
A R
AR
Stenzel
D
D
Powell
L W
LW
Halliday
J W
JW
D004705:Endocytosis; D005293:Ferritins / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007700:Kinetics; D008247:Lysosomes / Q000378:metabolism / Q000648:ultrastructure; D018613:Microscopy, Confocal; D011994:Recombinant Proteins; D013601:T-Lymphocytes / Q000378:metabolism* / Q000648:ultrastructure; D014407:Tumor Cells, Cultured / Q000378:metabolism
D007074:Immunoglobulin G; D011994:Recombinant Proteins; D005293:Ferritins; D016650:Fluorescein-5-isothiocyanate