An inhibitory fragment derived from protein kinase Cepsilon prevents enhancement of nerve growth factor responses by ethanol and phorbol esters.
We have studied nerve growth factor (NGF)-induced differentiation of PC12 cells to identify PKC isozymes important for neuronal differentiation. Previous work showed that tumor-promoting phorbol esters and ethanol enhance NGF-induced mitogen-activated protein (MAP) kinase activation and neurite outgrowth by a PKC-dependent mechanism. Ethanol also increases expression of PKCdelta and PKCepsilon, suggesting that one these isozymes regulates responses to NGF. To examine this possibility, we established PC12 cell lines that express a fragment encoding the first variable domain of PKCepsilon (amino acids 2-144), which acts as an isozyme-specific inhibitor of PKCepsilon in cardiac myocytes. Phorbol ester-stimulated translocation of PKCepsilon was markedly reduced in these PC12 cell lines. In addition, phorbol ester and ethanol did not enhance NGF-induced MAP kinase activation or neurite outgrowth in these cells. In contrast, phorbol ester and ethanol increased neurite outgrowth and MAP kinase phosphorylation in cells expressing a fragment derived from the first variable domain of PKCdelta. These results demonstrate that PKCepsilon mediates enhancement of NGF-induced signaling and neurite outgrowth by phorbol esters and ethanol in PC12 cells.
Hundle
B
B
Department of Neurology and Ernest Gallo Clinic and Research Center, University of California, San Francisco, California 94110, USA.
McMahon
T
T
Dadgar
J
J
Chen
C H
CH
Mochly-Rosen
D
D
Messing
R O
RO
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004357:Drug Synergism; D004789:Enzyme Activation; D000431:Ethanol / Q000494:pharmacology*; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry*; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D016716:PC12 Cells; D010446:Peptide Fragments / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000096:biosynthesis* / Q000737:chemistry*; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014162:Transfection
D007527:Isoenzymes; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D000431:Ethanol; C497260:Prkcd protein, rat; C497257:Prkce protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate