Akt phosphorylates Connexin43 on Ser373, a "mode-1" binding site for 14-3-3.
Connexin43 (Cx43) is a membrane-spanning protein that forms channels that bridge the gap between adjacent cells and this allows for the intercellular exchange of information. Cx43 is regulated by phosphorylation and by interacting proteins. "Mode-1" interaction with 14-3-3 requires phosphorylation of Ser373 on Cx43 (Park et al. 2006). Akt phosphorylates and targets a number of proteins to interactions with 14-3-3. Here we demonstrate that Akt phosphorylates Cx43 on Ser373 and Ser369; antibodies recognizing Akt-phosphorylated sites or phospho-Ser "mode-1" 14-3-3-binding sites recognize a protein from EGF-treated cells that migrates as Cx43, and GST-14-3-3 binds to Cx43 phosphorylated endogenously in EGF-treated cells. Confocal microscopy supports the co-localization of Cx43 with Akt and with 14-3-3 at the outer edges of gap junctional plaques. These data suggest that Akt could target Cx43 to an interaction with 14-3-3 that may play a role in the forward trafficking of Cx43 multimers and/or their incorporation into existing gap junctional plaques.
Park
Darren J
DJ
Natural Products & Cancer Biology Program, Cancer Research Center, University of Hawaii at Manoa, Honolulu, Hawaii 96813, USA.
Wallick
Christopher J
CJ
Martyn
Kendra D
KD
Lau
Alan F
AF
Jin
Chengshi
C
Warn-Cramer
Bonnie J
BJ
D048948:14-3-3 Proteins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002465:Cell Movement / Q000502:physiology; D018031:Connexin 43 / Q000737:chemistry / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D046911:Macromolecular Substances / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000378:metabolism
D048948:14-3-3 Proteins; D018031:Connexin 43; D046911:Macromolecular Substances; D012694:Serine; D004815:Epidermal Growth Factor; D051057:Proto-Oncogene Proteins c-akt