Steel factor stimulates the serine/threonine phosphorylation of the interleukin-3 receptor.
The murine interleukin-3 (IL-3) dependent cell line, B6SUtA1, which expresses high IL-3 receptor (IL-3R) numbers, was found to proliferate in a greater than additive fashion when grown in the presence of IL-3 and steel factor (SF). However, pretreatment of these cells with SF had no effect on the number of IL-3Rs expressed at the cell surface nor their affinity for IL-3. Interestingly, although, SF did induce the rapid and transient serine- and threonine-specific phosphorylation of the beta IL-3 subunit of the IL-3R. This serine/threonine phosphorylation was also observed with the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, and both the 12-O-tetradecanoylphorbol-13-acetate- and SF-induced phosphorylation of the IL-3R could be inhibited with the highly specific protein kinase C inhibitor, bisindolylmaleimide (Compound 3), suggesting that SF might be stimulating this phosphorylation via protein kinase C. This SF-induced phosphorylation also occurred within 10 min of incubation at 4 degrees C, indicating that this might be a relatively early event in the c-kit signaling pathway. Last, this SF-induced phosphorylation of the IL-3R occurred in the presence of the tyrosine kinase inhibitor, genistein, at levels which blocked the autophosphorylation of c-kit. This suggests that c-kit might be capable of mediating this cross-talk phenomenon in the absence of its endogenous tyrosine kinase activity.
Liu
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Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada.
Cutler
R L
RL
Mui
A L
AL
Krystal
G
G
D000818:Animals; D015815:Cell Adhesion Molecules / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology*; D007377:Interleukin-3 / Q000494:pharmacology*; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D010769:Phosphothreonine / Q000378:metabolism*; D016185:Receptors, Interleukin-3 / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D019089:Stem Cell Factor; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D014162:Transfection
D015815:Cell Adhesion Molecules; D016298:Hematopoietic Cell Growth Factors; D007377:Interleukin-3; D046911:Macromolecular Substances; D010710:Phosphates; D010750:Phosphoproteins; D016185:Receptors, Interleukin-3; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D010769:Phosphothreonine; D010768:Phosphoserine; D004247:DNA; D013755:Tetradecanoylphorbol Acetate; D013936:Thymidine