Complete inhibition of transferrin recycling by monensin in K562 cells

• Published in: The Journal of biological chemistry 1984-12, Vol.259 (23), p.14762-14772
• Main Authors: Stein, B S, Bensch, K G, Sussman, H H
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Cell Line; Chloroquine - pharmacology; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Furans - pharmacology; Humans; Kinetics; Leukemia, Myeloid, Acute; Metalloproteins; Microscopy, Electron; Monensin - pharmacology; Other metalloproteins; Proteins; Receptors, Cell Surface - analysis; Receptors, Cell Surface - metabolism; Receptors, Transferrin; Transferrin - antagonists & inhibitors
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)42668-8

Monensin blocks human transferrin recycling in a dose-dependent and reversible manner in K562 cells, reaching 100% inhibition at a noncytocidal dose of 10(-5) M, whereas transferrin recycling is virtually unaffected by noncytocidal doses of chloroquine. The intracellular pathway of human transferrin in K562 cells, both in the presence and absence of 10(-5) M monensin, was localized by indirect immunofluorescence. Monensin blocks transferrin recycling by causing internalized ligand to accumulate in the perinuclear region of the cell. The effect of 10(-5) M monensin on human transferrin kinetics was quantitatively measured by radioimmunoassay and showed a positive correlation with immunofluorescent studies. Immunoelectron microscopic localization of human transferrin as it cycles through K562 cells reveals the appearance of perinuclear transferrin-positive multivesicular bodies within 3 min of internalization, with subsequent exocytic delivery of the ligand to the cell surface via transferrin-staining vesicles arising from these perinuclear structures within 5 min of internalization. Inhibition of ligand recycling with 10(-5) M monensin causes dilated transferrin-positive multivesicular bodies to accumulate within the cell with no evidence of recycling vesicles. A coordinated interaction between multivesicular bodies and the Golgi apparatus appears to be involved in the recycling of transferrin in K562 cells. Cell-surface-binding sites for transferrin were reduced by 50% with 10(-5) M monensin treatment; however, this effect was not attenuated by 80% protein synthesis inhibition with cycloheximide, supporting the idea that the transferrin receptor is also recycled through the Golgi.