Internalisation and recycling of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor on a murine myelomonocytic leukemia

✍ Scribed by Francesca Walker; Antony W. Burgess

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 791 KB
• Volume: 130
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041300211

✦ Synopsis

Radioiodinated granulocyte-macrophage colony-stimulating factor (1251-GM-CSF) binds to specific receptors (molecular weight approximately 50,000 daltons) on the murine myelomonocytic leukemia, WEHI-3BD+. At 4OC 1251-CM-CSF remains on the surface of the cells and can be eluted by washing the cells with acidified isotonic buffer. When the cells are warmed to 37OC, the 1251-GM-CSF is internalized rapidly (t%: 7 min). The internalisation appears to be entirely receptor mediated and is independent of energy sources inhibited by sodium azide. This GM-CSF-mediated internalisation is not due to a general increase in t h e turnover of cell surface molecules as the specific binding of 1251-transferrin is not affected by incubation of WEHI-3BD+ cells with GM-CSF. The initial lZ5l released when the cells are warmed to 37OC appears to be intact 1251-GM-CSF; however, after 2 h 80% of the lZ5l released was not precipitable with trichloroacetic acid and presumably represented degraded 251-GM-CSF. Ammonium chloride or monensin reduced the release of lZ5l-GM-CSF from the cells, suggesting that the receptor-bound ligand was processed through the lysosomes. A considerable proportion of the internalised GM-CSF receptors were recycled to the surface and were available for ligand binding. Synthesis of new GM-CSF receptors contributed to the re-expression of GM-CSF receptors after down-regulation and it is possible that the GM-CSF enhances the synthesis of its own receptors.