Dynamics of toxin and lectin receptors on a lymphoma cell line and its toxin-resistant variant using ferritin-conjugated, 125I-labeled ligand.

Abstract

The dynamics of the toxin Ricinus communis agglutinin II (RCAII or ricin) on cells of a murine lymphoma line (BW5147) and a toxin-resistant variant line (BW5147RicR.3) that is 200 times more resistant than the parent to direct RCAII cytotoxicity were examined using ferritin-conjugated, affinity purified, 125I-labeled RCAII (ferritin-125I-RCAII). Ferritin-125I-RCAII was indistinguishable from native RCAII in quantitative binding and cytotoxicity experiments. When RCAII-sensitive BW5147 and -resistant BW5147RicR.3 cells were labeled with ferritin-125I-RCAII at various toxin concentrations (1--10 microgram/ml), no differences in toxin binding were observed. These same cells were examined by electron microscopy. At low ferritin-125I-RCAII concentrations (1-3 microgram/ml RCAII) where only the parental BW5147 cells were significantly more sensitive to RCAII, toxin receptors were internalized by ferritin-125I-RCAII-induced endocytosis. In parallel experiments, ferritin-125I-RCAII that bound to the resistant BW5147RicR.3 cells remained relatively dispersed or clustered, and there was little evidence of transport into cells via endocytosis. At higher ferritin-125I-RCAII concentrations (greater than 7 microgram/ml RCAII) where both parental and resistant variant cells are sensitive to the cytotoxic effects of RCAII, more ferritin-conjugated toxin was bound, and subsequent endocytosis occurred to a similar degree in both cell types. Endocytosis of ferritin-conjugated concanavalin A was indistinguishable on RCAII-sensitive parental and resistant variant cells at all concentrations tested. The results suggest that a specific defect on the selected BW5147RicR.3 cells prevents RCAII entry into these cells a low toxin concentrations, rendering them more resistant to the cytotoxic effects of RCAII.

• Authors: G L Nicolson, J R Smith, R Hyman
• Journal: The Journal of cell biology (J Cell Biol) Vol. 78 Issue 2 Pg. 565-76 (Aug 1978) ISSN: 0021-9525 [Print] United States
• PMID: 567654 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Iodine Radioisotopes
• Receptors, Concanavalin A
• Receptors, Drug
• Concanavalin A
• Ferritins
• Ricin

Topics

• Animals
• Cell Line
• Concanavalin A (metabolism)
• Drug Resistance
• Endocytosis
• Ferritins
• Genetic Variation
• Iodine Radioisotopes
• Lymphoma
• Mice
• Neoplasms, Experimental
• Receptors, Concanavalin A (metabolism)
• Receptors, Drug (metabolism)
• Ricin (metabolism, toxicity)