Protein kinase inhibitor H-7 differentially affects early and delayed nerve growth factor responses in PC12 cells.
The effects of the protein kinase inhibitor H-7 on early and delayed responses to nerve growth factor (NGF) were investigated in PC12 cells. H-7 reduced the NGF-induced expression of c-Fos in a dose-dependent manner without affecting the time course of c-Fos appearance. Conversely, H-7 potentiated delayed NGF effects, i.e., neurite outgrowth and Ca2+/phospholipid-dependent protein kinase (PKC) induction, but not choline acetyltransferase induction. Long-term treatment with NGF resulted in an increase of at least four tyrosine-phosphorylated protein bands with molecular masses between 39 and 48 kDa, which was also potentiated by H-7. In the absence of NGF, H-7 had no significant effect on c-Fos expression, tyrosine phosphorylation of the 45 kDa protein, or choline acetyltransferase activity. However, 4 days of exposure to H-7 alone induced PKC activity and tyrosine phosphorylation of the 39-kDa protein. The action of H-7 derivatives on neurite outgrowth did not correlate with their inhibition profile of cyclic nucleotide-dependent protein kinases. Down-regulation of PKC activity by prolonged exposure to phorbol ester did not completely abolish the effects of NGF and H-7 on induction of c-Fos, choline acetyltransferase activity, and neurite outgrowth, indicating that PKC-independent pathways contribute to these actions. These results suggest that additional pathway(s) sensitive to H-7 may exist, which induce immediate early gene expression and suppress neuronal differentiation of PC12 cells.
Kahle
P
P
Pharma Division, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
Mangold
M
M
Kuwahara
T
T
Schubenel
R
R
Hertel
C
C
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D007546:Isoquinolines / Q000494:pharmacology*; D009414:Nerve Growth Factors / Q000378:metabolism*; D009994:Osmolar Concentration; D016716:PC12 Cells; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism
D007546:Isoquinolines; D009414:Nerve Growth Factors; D010879:Piperazines; D016760:Proto-Oncogene Proteins c-fos; D014443:Tyrosine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C