Translocation and activation of protein kinase C in striatal neurons in primary culture: relationship to phorbol dibutyrate actions on the inositol phosphate generating system and neurotransmitter release.
The actions of the tumor-promoting phorbol ester phorbol dibutyrate were examined, under identical physiological conditions, on three distinct cellular processes in striatal neurons: the distribution of protein kinase C, the carbachol-stimulated generation of [3H]inositol monophosphate, and the KCl-evoked release of gamma-[3H]aminobutyric acid ([3H]GABA). Phorbol dibutyrate induced a rapid (complete in 5 min), dose-dependent, entirely reversible (t0.5 = 15 min) translocation of protein kinase C from cytosol to membrane. On longer exposure to phorbol dibutyrate, membrane-associated protein kinase C returned toward the control level, and total cellular enzyme activity declined markedly. Phorbol dibutyrate also induced the dose-dependent attenuation of carbachol-stimulated [3H]inositol monophosphate production and potentiation of KCl-evoked release of [3H]GABA. The translocation of protein kinase C and the potentiation of KCl-evoked [3H]GABA release were both rapidly reversed following washout of phorbol dibutyrate. In addition, for both processes, the effect of a 1-h exposure to phorbol dibutyrate was markedly less than that observed following a 5-min exposure to the agent. In direct contrast, inhibition of carbachol-stimulated [3H]inositol monophosphate production was not rapidly reversed following washout of phorbol dibutyrate and was actually more pronounced following a 1-h exposure, compared with a 5-min exposure. These findings indicate that some, but not all, of the actions of phorbol dibutyrate are closely associated with the translocation of protein kinase C in striatal neurons in primary culture.
Weiss
S
S
Department of Psychiatry, University of Vermont College of Medicine, Burlington.
Ellis
J
J
Hendley
D D
DD
Lenox
R H
RH
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D009474:Neurons / Q000201:enzymology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D013403:Sugar Phosphates / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D007295:Inositol Phosphates; D018377:Neurotransmitter Agents; D013403:Sugar Phosphates; D015240:Phorbol 12,13-Dibutyrate; D005680:gamma-Aminobutyric Acid; D011189:Potassium Chloride; D002217:Carbachol; D011493:Protein Kinase C