title: The role of protein kinase C alpha and epsilon isozymes in DNA synthesis induced by muscarinic receptors in a glial cell line.
abstract: Acetylcholine has been shown to induce proliferation of human astrocytoma cells by activating muscarinic receptors, particularly the m3 subtype. In the present study the role of protein kinase C in DNA synthesis induced by carbachol has been investigated. Carbachol-induced [methyl-3H]thymidine incorporation was inhibited by the protein kinase C inhibitors GF 109203X and staurosporine. However, carbachol-induced DNA synthesis was only partially reduced by protein kinase C down-regulation by phorbol 12-myristate 13-acetate (PMA), and maximal concentrations of carbachol and PMA had an additive effect on [methyl-3H]thymidine incorporation. Exposure for 24 h to maximally effective concentrations of carbachol did not induce down-regulation of protein kinase C alpha, and caused a small but significant down-regulation of protein kinase C epsilon; cells exposed for 24 h to carbachol were still able to respond with protein kinase C translocation to PMA stimulation. Carbachol caused a significant increase of phorbol ester binding, but did not stimulate protein kinase C alpha translocation, while it caused a short-lasting translocation of protein kinase C epsilon; however, protein kinase C epsilon translocation was not correlated with the time-course of carbachol-induced increase in [methyl-3H]thymidine incorporation. On the other hand, the time-course of translocation/down-regulation of protein kinase C alpha and protein kinase C epsilon induced by PMA was in good correlation with the time-course of PMA-induced [methyl-3H]thymidine incorporation. These results suggest that protein kinase C alpha may not be involved in DNA synthesis induced by muscarinic receptors stimulation in 132-1N1 astrocytoma cells, while protein kinase C epsilon appears to play a role in the initial exit from G0/G1 phase, though it cannot be considered the major determinant for sustained proliferation.
authors.affiliation: Department of Environmental Health, University of Washington, Seattle 98105, USA.
authors.forename: M
authors.initials: M
authors.lastname: Guizzetti
authors.forename: M
authors.initials: M
authors.lastname: Wei
authors.forename: L G
authors.initials: LG
authors.lastname: Costa
mesh_terms: D001254:Astrocytoma; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis* / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008301:Maleimides / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D002273:Carcinogens; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D001285:Atropine; D002217:Carbachol; D004247:DNA; C496628:PRKCA protein, human; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D019311:Staurosporine; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate