title: Regulation of connexin-43 gap junctional intercellular communication by mitogen-activated protein kinase.
abstract: Activation of the Ras/Raf/mitogen-activated protein kinase kinase/mitogen-activated protein (MAP) kinase signaling cascade is initiated by activation of growth factor receptors and regulates many cellular events, including cell cycle control. Our previous studies suggested that the connexin-43 gap junction protein may be a target of activated MAP kinase and that MAP kinase may regulate connexin-43 function. We identified the sites of MAP kinase phosphorylation in in vitro studies as the consensus MAP kinase recognition sites in the cytoplasmic carboxyl tail of connexin-43, Ser255, Ser279, and Ser282. In this study, we demonstrate that activation of MAP kinase by ligand-induced activation of the epidermal growth factor (EGF) or lysophosphatidic acid receptors or by pervanadate-induced inhibition of tyrosine phosphatases results in increased phosphorylation on connexin-43. EGF and lysophosphatidic acid-induced phosphorylation on connexin-43 and the down-regulation of gap junctional communication in EGF-treated cells were blocked by a specific mitogen-activated protein kinase kinase inhibitor (PD98059) that prevented activation of MAP kinase. These studies confirm that connexin-43 is a MAP kinase substrate in vivo and that phosphorylation on Ser255, Ser279, and/or Ser282 initiates the down-regulation of gap junctional communication. Studies with connexin-43 mutants suggest that MAP kinase phosphorylation at one or more of the tandem Ser279/Ser282 sites is sufficient to disrupt gap junctional intercellular communication.
authors.affiliation: Molecular Carcinogenesis Section, Cancer Research Center of Hawaii, University of Hawaii at Manoa, Honolulu, Hawaii 96813, USA. bwcramer@crch.hawaii.edu
authors.forename: B J
authors.initials: BJ
authors.lastname: Warn-Cramer
authors.forename: G T
authors.initials: GT
authors.lastname: Cottrell
authors.forename: J M
authors.initials: JM
authors.lastname: Burt
authors.forename: A F
authors.initials: AF
authors.lastname: Lau
mesh_terms: D000818:Animals; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D018031:Connexin 43 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D010766:Phosphorylation; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis; D012694:Serine; D015398:Signal Transduction; D014162:Transfection
chemical_list: D018031:Connexin 43; D004791:Enzyme Inhibitors; D005419:Flavonoids; D008246:Lysophospholipids; D011994:Recombinant Proteins; D012694:Serine; D004815:Epidermal Growth Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one