Opioid peptides activate phospholipase D and protein kinase C-epsilon in chicken embryo neuron cultures.
The mu-opioid peptide morphiceptin stimulated a Ca(2+)-independent protein kinase C (PKC-epsilon) that is expressed both in embryonic day 6 chicken telencephalon and in derived neuronal cultures. This activation was seen as a 2-fold increase in the activity and level of cytosolic PKC-epsilon and as a transient increase in membrane-associated PKC-epsilon following morphiceptin treatment. Morphiceptin did not activate phospholipase C-mediated phosphatidylinositol hydrolysis but did transiently activate (2- to 3-fold) phospholipase D (PLD), as measured by phosphatidylethanol formation in neuron cultures derived from embryonic day 6 or day 7 cerebral hemispheres. This PLD activation could provide an alternative source of diacylglycerol for the activation of PKC-epsilon and was naloxone-reversible and at least partially blocked by the tyrosine kinase inhibitor herbimycin A. Addition of phorbol 12-myristate 13-acetate stimulated both PLD and PKC-epsilon activities to a greater extent than opioids. The phorbol ester and insulin stimulation of PLD was also blocked by herbimycin. Both morphiceptin (in a naloxone-reversible manner) and phorbol ester increased phosphorylation of similar cytosolic proteins in intact cells, demonstrating a functional role for the PKC-epsilon activation by opioids. This is evidence that opioid receptors are transiently coupled to tyrosine kinase, PLD and PKC-epsilon activation and, by implication, to neuronal cell growth during brain morphogenesis.
Mangoura
D
D
Department of Pediatrics, University of Chicago, IL 60637.
Dawson
G
G
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D016227:Benzoquinones; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D002642:Chick Embryo; D004723:Endorphins / Q000494:pharmacology*; D004789:Enzyme Activation; D007328:Insulin / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D047029:Lactams, Macrocyclic; D009474:Neurons / Q000201:enzymology*; D010739:Phospholipase D / Q000378:metabolism*; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors
D000700:Analgesics; D016227:Benzoquinones; D004723:Endorphins; D007328:Insulin; D007527:Isoenzymes; D047029:Lactams, Macrocyclic; D010750:Phosphoproteins; D011809:Quinones; D017828:Rifabutin; C020754:herbimycin; C028889:morphiceptin; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium