title: Activation of RISK and SAFE pathways is not involved in the effects of Cx43 deficiency on tolerance to ischemia-reperfusion injury and preconditioning protection.
abstract: Connexin 43 (Cx43) deficiency increases myocardial tolerance to ischemia-reperfusion injury and abolishes preconditioning protection. It is not known whether modifications in baseline signaling through protective RISK or SAFE pathways or in response to preconditioning may contribute to these effects. To answer this question we used Cx43(Cre-ER(T)/fl) mice, in which Cx43 expression is abolished after 4-hydroxytamoxifen (4-OHT) administration. Isolated hearts from Cx43(Cre-ER(T)/fl) mice, or from Cx43(fl/fl) controls, treated with vehicle or 4-OHT, were submitted to global ischemia (40 min) and reperfusion. Cx43 deficiency was associated with reduced infarct size after ischemia-reperfusion (11.17 ± 3.25 % vs. 65.04 ± 3.79, 59.31 ± 5.36 and 65.40 ± 4.91, in Cx43(fl/fl) animals treated with vehicle, Cx43(fl/fl) mice treated with 4-OHT, and Cx43(Cre-ER(T)/fl) mice treated with vehicle, respectively, n = 8-9, p < 0.001). However, the ratio phosphorylated/total protein expression for Akt, ERK-1/2, GSK3β and STAT3 was not increased in normoxic samples from animals lacking Cx43. Instead, a reduction in the phosphorylation state of GSK3β was observed in Cx43-deficient mice (ratio: 0.15 ± 0.02 vs. 0.56 ± 0.11, 0.77 ± 0.15, and 0.46 ± 0.14, respectively, n = 5-6, p < 0.01). Furthermore, ischemic preconditioning (IPC, 4 cycles of 3.5 min of ischemia and 5 min of reperfusion) increased phosphorylation of ERK-1/2, GSK3β, and STAT3 in all hearts without differences between groups (n = 5-6, p < 0.05), although Cx43 deficient mice were not protected by either IPC or pharmacological preconditioning with diazoxide. Our data demonstrate that modification of RISK and SAFE signaling does not contribute to the role of Cx43 in the increased tolerance to myocardial ischemia-reperfusion injury and in preconditioning protection.
authors.affiliation: Laboratorio de Cardiología Experimental, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Pg. Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Sánchez
authors.forename: Antonio
authors.initials: A
authors.lastname: Rodríguez-Sinovas
authors.forename: Ignasi
authors.initials: I
authors.lastname: Barba
authors.forename: Elisabet
authors.initials: E
authors.lastname: Miró-Casas
authors.forename: Celia
authors.initials: C
authors.lastname: Fernández-Sanz
authors.forename: Marisol
authors.initials: M
authors.lastname: Ruiz-Meana
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Alburquerque-Béjar
authors.forename: David
authors.initials: D
authors.lastname: García-Dorado
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016923:Cell Death; D018031:Connexin 43 / Q000172:deficiency* / Q000235:genetics; D004195:Disease Models, Animal; D004734:Energy Metabolism; D004789:Enzyme Activation; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D019157:Ischemic Preconditioning, Myocardial; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009203:Myocardial Infarction / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D010725:Phosphocreatine / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
chemical_list: D018031:Connexin 43; D047428:Protein Kinase Inhibitors; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; C535148:Mapk1 protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D038362:Glycogen Synthase Kinase 3