Reversible Connexin 43 Dephosphorylation During Hypoxia and Reoxygenation Is Linked to Cellular ATP Levels

Autor: Mark S. Turner, Keith A. Webster, Nanette H. Bishopric, Patricia E. M. Martin, W. Howard Evans, Péter Andréka, Guy A. Haywood, Lijing You
Rok vydání: 2004
Předmět:
Indoles
Pyridines
Physiology
Antimycin A
Connexin
Maleimides
Adenosine Triphosphate
Myocytes
Cardiac
Glycolysis
Protein phosphorylation
Cycloheximide
Phosphorylation
Ouabain
Cells
Cultured
Kinase
Imidazoles
Cell Hypoxia
Phenanthridines
Cell biology
Biochemistry
cardiovascular system
Tetradecanoylphorbol Acetate
biological phenomena
cell phenomena
and immunity
Cardiology and Cardiovascular Medicine
Recombinant Fusion Proteins
Carbazoles
Deoxyglucose
Biology
Tacrolimus
Dephosphorylation
Alkaloids
Okadaic Acid
Animals
Pyrroles
Potassium Cyanide
Protein kinase A
Protein kinase C
Benzophenanthridines
Flavonoids
Brefeldin A
JNK Mitogen-Activated Protein Kinases
Ribonucleotides
Aminoimidazole Carboxamide
Staurosporine
Myocardial Contraction
Rats
Connexin 43
sense organs
Protein Processing
Post-Translational
Zdroj: Circulation Research. 95:726-733
ISSN: 1524-4571
0009-7330
DOI: 10.1161/01.res.0000144805.11519.1e
Popis: Altered gap junction coupling of cardiac myocytes during ischemia may contribute to development of lethal arrhythmias. The phosphoprotein connexin 43 (Cx43) is the major constituent of gap junctions. Dephosphorylation of Cx43 and uncoupling of gap junctions occur during ischemia, but the significance of Cx43 phosphorylation in this setting is unknown. Here we show that Cx43 dephosphorylation in synchronously contracting myocytes during ischemia is reversible, independent of hypoxia, and closely associated with cellular ATP levels. Cx43 became profoundly dephosphorylated during hypoxia only when glucose supplies were limited and was completely rephosphorylated within 30 minutes of reoxygenation. Similarly, direct reduction of ATP by various combinations of metabolic inhibitors and by ouabain was closely paralleled by loss of phosphoCx43 and recovery of phosphoCx43 accompanied restoration of ATP. Dephosphorylation of Cx43 could not be attributed to hypoxia, acid pH or secreted metabolites, or to AMP-activated protein kinase; moreover, the process was selective for Cx43 because levels of phospho-extracellular signal regulated kinase (ERK)1/2 were increased throughout. Rephosphorylation of Cx43 was not dependent on new protein synthesis, or on activation of protein kinases A or G, ERK1/2, p38 mitogen-activated protein kinase, or Jun kinase; however, broad-spectrum protein kinase C inhibitors prevented Cx43 rephosphorylation while also sensitizing myocytes to reoxygenation-mediated cell death. We conclude that Cx43 is reversibly dephosphorylated and rephosphorylated during hypoxia and reoxygenation by a novel mechanism that is sensitive to nonlethal fluctuations in cellular ATP. The role of this regulated phosphorylation in the adaptation to ischemia remains to be determined.
Databáze: OpenAIRE
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