SB203580 promotes EGF-stimulated early morphological differentiation in PC12 cell through activating ERK pathway.
MAP kinases have important role in PC12 cell differentiation, since the activities of both extracellular regulated protein kinase (ERK) and p38 have been indicated as necessary signal for PC12 cell differentiation. Epidermal growth factor (EGF) and NGF both activate ERK and p38 in PC12 cells, but only NGF trigger differentiation. It has been proposed that the duration of ERK activation determines the switch from proliferation to differentiation, since EGF causes more transient activation of ERK than NGF in PC12 cells. Here we report that treatment of PC12 cells with EGF in the presence of SB203580, a widely used p38 inhibitor, caused differentiation. The pro-differentiation effect of SB203580 in EGF-treated PC12 cells was found to be independent of its function of p38 inhibition but was through an effect on the ERK pathway that has been recently reported (Kalmes et al. [1999] FEBS Lett. 444: 71-74; Hall-Jackson et al. [1999] Onc. 18: 2047-2054). We found that SB203580 by itself did not affect the activity of ERK1/2 but significantly extended EGF-induced ERK activation in PC12 cells, which resulted in early morphological differentiation. Our data indicated that although both ERK and p38 are required for PC12 cell differentiation, activation of p38 is not required when ERK is superactivated. Our data provided further evidence for the threshold theory that differentiation is determined by the duration of ERK activation.
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Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA. linew@scripps.edu
Li
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Y
Ge
B
B
Zhong
H
H
Mansbridge
J
J
Liu
K
K
Han
J
J
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D004338:Drug Combinations; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005822:Genetic Vectors / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D020932:Nerve Growth Factor / Q000494:pharmacology; D016716:PC12 Cells; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D004338:Drug Combinations; D004791:Enzyme Inhibitors; D007093:Imidazoles; D010446:Peptide Fragments; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D020932:Nerve Growth Factor; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580