Overexpression of epsilon-protein kinase C enhances nerve growth factor-induced phosphorylation of mitogen-activated protein kinases and neurite outgrowth.
Protein kinase C (PKC) activation enhances neurite outgrowth in several cell lines and primary neurons. The PKC isozymes that mediate this response are unknown. One clue to their identity has come from studies using PC12 cells treated with ethanol. In these cells, ethanol increases levels of delta-PKC and epsilon-PKC and markedly enhances nerve growth factor (NGF)-induced neurite outgrowth and activation of mitogen-activated protein (MAP) kinases by a PKC-dependent mechanism. Since these findings suggest that delta-PKC or epsilon-PKC can promote neural differentiation, we studied neurite outgrowth in stably transfected PC12 cell lines that overexpress these isozymes. Overexpression of epsilon-PKC markedly increased NGF-induced neurite outgrowth. This effect was blocked by down-regulating PKC or by treating cells with the PKC inhibitor GF 109203X. In addition, overexpression of epsilon-PKC enhanced NGF-induced phosphorylation of MAP kinases. In contrast, overexpression of delta-PKC did not alter responses to NGF. These results demonstrate that epsilon-PKC promotes NGF-induced neurite outgrowth by enhancing NGF signal transduction. These findings suggest a role for epsilon-PKC in neural differentiation and plasticity.
Hundle
B
B
Ernest Gallo Clinic & Research Center, Department of Neurology, University of California, San Francisco 94110, USA.
McMahon
T
T
Dadgar
J
J
Messing
R O
RO
D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002454:Cell Differentiation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000032:analysis / Q000096:biosynthesis* / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016501:Neurites / Q000502:physiology*; D016716:PC12 Cells; D010455:Peptides / Q000138:chemical synthesis; D010766:Phosphorylation; D011493:Protein Kinase C / Q000032:analysis / Q000096:biosynthesis* / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism; D013379:Substrate Specificity; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D009414:Nerve Growth Factors; D010455:Peptides; D011994:Recombinant Proteins; D000431:Ethanol; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate