title: Distinct regulation of expressed calcium channels 2.3 in Xenopus oocytes by direct or indirect activation of protein kinase C.
abstract: Protein kinase C (PKC)-dependent regulation of voltage-gated Ca (Ca(v); with alpha(1)beta1Balpha2/delta subunits) channel 2.3 was investigated using phorbol 12-myristate 13-acetate (PMA), or by M(1) muscarinic receptor activation in Xenopus oocytes. The inward Ca(2+)-current with Ba(2+) (I(Ba)) as the charge carrier was potentiated by PMA or acetyl-beta-methylcholine (MCh). The inactivating [I(inact)] and non-inactivating [I(noninact)] components of I(Ba) and the time constant of inactivation tau(inact) were all increased by MCh or PMA. This may be a PKC-dependent action since the effect of MCh and PMA was blocked by Ro-31-8425 or beta-pseudosubstrate. MCh effect was blocked by atropine, guanosine-5'-O-(2-thiodiphosphate) trilithium (GDPbetaS) or U-73122. The effect of MCh but not PMA was blocked by the inhibition of inositol-1,4,5-trisphosphate (IP3) receptors, intracellular Ca(2+) ([Ca(2+)](i)) or the translocation of conventional PKC (cPKC) with heparin, BAPTA and betaC2.4, respectively. While a lower concentration (25 nM) of Ro-31-8425 blocked MCh, a higher concentration (500 nM) of Ro-31-8425 was required to block PMA action. This differential susceptibility of MCh and PMA to heparin, BAPTA, betaC2.4 or Ro-31-8425 is suggestive of the involvement of Ca(2+)-dependent cPKC in MCh action, whereas cPKC and Ca(2+)-independent novel PKC (nPKC) in PMA action. PMA led to additional increase in I(Ba) that was already potentiated by preadministered MCh (1 or 10 microM), leading to the suggestion that differential phosphorylation sites for cPKC and nPKC may be present in the alpha(1)2.3 subunit of Ca(v) 2.3 channels.
authors.affiliation: Department of Anesthesiology, P.O. Box 800710, University of Virginia Health Sciences Systems, Charlottesville, VA 22908-0710, USA. gk3p@virginia.edu
authors.forename: Ganesan L
authors.initials: GL
authors.lastname: Kamatchi
authors.forename: Shveta N
authors.initials: SN
authors.lastname: Tiwari
authors.forename: Carrie K
authors.initials: CK
authors.lastname: Chan
authors.forename: Daguang
authors.initials: D
authors.lastname: Chen
authors.forename: Sang-Hwan
authors.initials: SH
authors.lastname: Do
authors.forename: Marcel E
authors.initials: ME
authors.lastname: Durieux
authors.forename: Carl
authors.initials: C
authors.lastname: Lynch
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001464:Barium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D020908:Calcium Channels, R-Type; D002273:Carcinogens / Q000494:pharmacology; D027682:Cation Transport Proteins; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D016210:Methacholine Chloride / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D011741:Pyrimidine Nucleosides / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D043643:Receptor, Muscarinic M1; D011976:Receptors, Muscarinic / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D013997:Time Factors; D014981:Xenopus
chemical_list: C423009:CACNA1E protein, human; C425903:CACNA2D1 protein, human; D015220:Calcium Channels; D020908:Calcium Channels, R-Type; D002273:Carcinogens; D027682:Cation Transport Proteins; D004791:Enzyme Inhibitors; D004963:Estrenes; D007211:Indoles; D008301:Maleimides; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D010726:Phosphodiesterase Inhibitors; D011741:Pyrimidine Nucleosides; D011760:Pyrrolidinones; D043643:Receptor, Muscarinic M1; D011976:Receptors, Muscarinic; D013873:Thionucleotides; C096786:pseudothymidine; D016210:Methacholine Chloride; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C071924:Ro 31-8425; D006153:Guanosine Diphosphate; D001464:Barium; C023427:guanosine 5'-O-(2-thiodiphosphate); D001285:Atropine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate