IL-1 stimulates a diverging signaling pathway in EL4 6.1 thymoma cells. IL-2 release, but not IL-2 receptor expression, is sensitive to pertussis toxin.
We reassessed the involvement of Bordetella pertussis toxin (PTX)-sensitive proteins in the IL-1 signaling pathway on the responses induced by IL-1 on the murine thymoma cell line EL4 6.1. We demonstrate that the ADP-ribosyltransferase activity of PTX, and not its cell-anchoring B oligomer part, is responsible for the inhibition of IL-1-induced IL-2 release, since 1) the concentration of PTX (< or = 1 ng/ml) required to block the secretion is 100 to 1000 times lower than the concentration needed with the B oligomer; and 2) the mutated PT-9K/129G, devoid of ADP-ribosyltransferase activity, was inactive at 100 ng/ml. We found that partial ADP-ribosylation of the Gi2/Gi3 proteins before stimulation with IL-1 was sufficient to obtain full inhibition of IL-2 release. PTX did not however inhibit the appearance on the cell surface of the high affinity IL-2 receptors or the IL-2 release induced by PMA. In addition, we show that PTX prevented the expression of the IL-2 mRNA induced by IL-1, without affecting the binding of IL-2 specific nuclear factors to the T cell distal element of the IL-2 promoter. Furthermore, PTX also inhibited IL-1-induced proliferation of non-transformed thymocytes. In conclusion, our results demonstrate that IL-1-induced IL-2 release is sensitive to PTX-catalyzed ADP-ribosylation and that IL-1 activates a diverging pathway on EL4 6.1 cells.
Zumbihl
R
R
INSERM Unit 431, University of Montpellier II, France.
Dornand
J
J
Fischer
T
T
Cabane
S
S
Rappuoli
R
R
Bouaboula
M
M
Casellas
P
P
Rouot
B
B
D000818:Animals; D001483:Base Sequence; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D007376:Interleukin-2 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D037342:Pertussis Toxin; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D015375:Receptors, Interleukin-2 / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D007375:Interleukin-1; D007376:Interleukin-2; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D010566:Virulence Factors, Bordetella; D011065:Poly(ADP-ribose) Polymerases; D037342:Pertussis Toxin; D013755:Tetradecanoylphorbol Acetate