title: Phosphorylation at Connexin43 Serine-368 Is Necessary for Myocardial Conduction During Metabolic Stress.
abstract: Connexin43 (Cx43) phosphorylation alters gap junction localization and function. In particular, phosphorylation at serine-368 (S368) has been suggested to alter gap junctional conductance, but previous reports have shown inconsistent results for both timing and functional effects of S368 phosphorylation. The objective of this study was to determine the functional effects of isolated S368 phosphorylation. We evaluated wild-type Cx43 (AdCx43) and mutations simulating permanent phosphorylation (Ad368E) or preventing phosphorylation (Ad368A) at S368. Function was assessed by optical mapping of electrical conduction in patterned cultures of neonatal rat ventricular myocytes, under baseline and metabolic stress (MS) conditions. Baseline conduction velocity (CV) was similar for all groups. In the AdCx43 and Ad368E groups, MS moderately decreased CV. Ad368A caused complete conduction block during MS. Triton-X solubility assessment showed no change in Cx43 location during conduction impairment. Western blot analysis showed that Cx43-S368 phosphorylation was present at baseline, and that it decreased during MS. Our data indicate that phosphorylation at S368 does not affect CV under baseline conditions, and that preventing S368 phosphorylation makes Cx43 hypersensitive to MS. These results show the critical role of S368 phosphorylation during stress conditions.
authors.affiliation: Heart and Vascular Research Center and Department of Physiology & Biophysics, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Michelle M J
authors.initials: MM
authors.lastname: Nassal
authors.affiliation: Cardiovascular Division, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Andreas A
authors.initials: AA
authors.lastname: Werdich
authors.affiliation: Heart and Vascular Research Center and Department of Physiology & Biophysics, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wan
authors.affiliation: Heart and Vascular Research Center and Department of Physiology & Biophysics, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Hoshi
authors.affiliation: Heart and Vascular Research Center and Department of Physiology & Biophysics, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Deschênes
authors.affiliation: Heart and Vascular Research Center and Department of Physiology & Biophysics, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Rosenbaum
authors.affiliation: Division of Cardiology, University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: J Kevin
authors.initials: JK
authors.lastname: Donahue
mesh_terms: D000200:Action Potentials; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010766:Phosphorylation; D017207:Rats, Sprague-Dawley; D012694:Serine; D015398:Signal Transduction; D013312:Stress, Physiological; D013997:Time Factors; D014162:Transfection; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D018031:Connexin 43; C580592:Gja1 protein, rat; D012694:Serine
keywords: conduction velocity, connexin43; metabolic stress; phosphorylation; serine 368