Protein kinase C-linked inactivation of the interleukin-1 receptor in a human transformed B-cell line.
The effect of tumor-promoting phorbol ester treatment on the binding of interleukin-1 beta (IL-1 beta) to specific cell surface receptors was investigated. A 1 h exposure of Raji human B lymphoma cells with the protein kinase C-activating phorbol ester, phorbol dibutyrate (PDBu), reduced IL-1 beta binding by up to 90% of control cells. This effect was dose-dependent and was not observed with 4-alpha-phorbol, an inactive tumor promoter. Analysis of 125I-labeled IL-1 beta binding to intact cells revealed that PDBu caused a 91% decrease in high-affinity cell-surface receptor number without an effect on receptor affinity. The phorbol ester response was rapid (30 min), observed both at 4 and 37 degrees C, and was preceded by the rapid translocation (t much less than 6 min) of protein kinase C (PKC) from the cytosol to the cell membrane. The PDBu-induced decrease in IL-1 beta receptor number was inhibited by prior incubation of cells for 30 min with the PKC inhibitor 1-(5-Isoquinoline sulfonyl)-2-methylpiperazine (H7). The decrease in receptor binding was not due to enhanced IL-1 beta receptor internalization or shedding into the extracellular medium, since a similar effect was observed with solubilized IL-1 beta receptor. The most likely explanation for the phorbol ester effect appears to be cell surface inactivation of IL-1 receptors. These data suggest that modulation of PKC activity could play a role in the regulation of the IL-1 beta receptor.
Horuk
R
R
Medical Products Department, E.I. du Pont de Nemours & Co., Glenolden Laboratory, PA 19036.
Gross
J L
JL
D001402:B-Lymphocytes; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D007700:Kinetics; D008223:Lymphoma; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011955:Receptors, Drug / Q000378:metabolism; D011971:Receptors, Immunologic / Q000187:drug effects / Q000378:metabolism*; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D007375:Interleukin-1; D010704:Phorbols; D011955:Receptors, Drug; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; C083141:phorbol ester binding protein; C027776:phorbol ester receptor; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; C033085:phorbol