Characterization of interleukin-7-induced changes in tyrosine phosphorylation and c-myc gene expression in normal human T cells.
Interleukin-7 (IL-7) is a growth factor involved in regulating lymphopoiesis. We have chosen to study the signal transduction pathway of IL-7 in normal human peripheral blood T lymphocytes. Two early events that occur as a consequence of specific ligand-receptor interaction were examined: activation of protein tyrosine kinases and induction of primary response gene expression. Following treatment of human peripheral blood T cells with IL-7, four cellular proteins with relative molecular weights of 95- (doublet), 105-, and 130-kd were rapidly tyrosine phosphorylated as detected by immunoblotting with an antiphosphotyrosine monoclonal antibody (MAB). The 105-kd tyrosine-phosphorylated protein was membrane-associated after IL-7 stimulation. Treatment of human peripheral blood T cells with IL-7 enhanced expression of the primary response gene c-myc approximately three-fold, as detected by Northern blotting, in the presence or absence of protein synthesis. The rate of c-myc gene transcription increased in the presence of IL-7 and could account for the observed elevation of c-myc RNA levels. In addition, IL-7 treatment induced a slight increase in c-myc message stability. Experiments performed with the protein tyrosine kinase inhibitor genistein and the serine-threonine kinase inhibitor 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7) demonstrated that these kinases were required for IL-7 enhancement of c-myc expression. Treatment with tetradecanoyl phorbol acetate (TPA), a potent activator of protein kinase C (PKC), in combination with IL-7 induced a level of c-myc expression greater than that elicited by either factor alone, suggesting that TPA and IL-7 utilize cooperative signaling pathways to increase c-myc gene expression.
Yip-Schneider
M T
MT
Department of Medicine (Hematology/Oncology), Indiana University School of Medicine, Indianapolis 46202-5121.
Horie
M
M
Broxmeyer
H E
HE
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D015152:Blotting, Northern; D002455:Cell Division; D015870:Gene Expression / Q000187:drug effects; D016259:Genes, myc; D006801:Humans; D015151:Immunoblotting; D015851:Interleukin-7 / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology; D008970:Molecular Weight; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D015851:Interleukin-7; D007546:Isoquinolines; D010750:Phosphoproteins; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D019000:Phosphotyrosine; D014443:Tyrosine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011494:Protein Kinases; D013755:Tetradecanoylphorbol Acetate