Erythropoietin induces biphasic activation of p70S6k: evidence for a different regulation of early and late phase of activation.
The murine erythroleukaemia cell line HCD-57 proliferates in response to erythropoietin. Stimulation of erythropoietin-deprived cells with the cytokine induces the phosphorylation and biphasic activation of the 70,000 M(r) S6 kinase. Two peaks of enzyme activity were observed after 30 and 120 min, respectively. Early and late phase of activation differ in their sensitivity to the protein kinase C inhibitor staurosporine suggesting different regulatory mechanisms.
Institute of Medical Biochemistry, Medical Faculty of the University of Rostock, Germany.
R
R
Jaster
T
T
Bittorf
M
M
Markewitz
G
G
Selig
J
J
Brock
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002470:Cell Survival; D004273:DNA, Neoplasm / Q000032:analysis; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004921:Erythropoietin / Q000494:pharmacology*; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D004915:Leukemia, Erythroblastic, Acute / Q000188:drug therapy / Q000201:enzymology*; D051379:Mice; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases; D015398:Signal Transduction; D019311:Staurosporine; D014407:Tumor Cells, Cultured
D000470:Alkaloids; D004273:DNA, Neoplasm; D004791:Enzyme Inhibitors; D007529:Isoflavones; D004921:Erythropoietin; D019833:Genistein; D017346:Protein Serine-Threonine Kinases; D019893:Ribosomal Protein S6 Kinases; D011493:Protein Kinase C; D019311:Staurosporine