title: c-Jun N-terminal kinase activation contributes to reduced connexin43 and development of atrial arrhythmias.
abstract: OBJECTIVE
  c-Jun N-terminal kinase (JNK) activation is implicated in cardiovascular diseases and ageing, which are linked to enhanced propensity to atrial fibrillation (AF). However, the contribution of JNK to AF remains unknown. Thus, we assessed the role of JNK in remodelling of gap junction connexin43 (Cx43) and development of AF.
  
  
  RESULTS
  AF induction, optical mapping, and biochemical assays were performed in young and aged New Zealand white rabbit left atria (LA) and cultured HL-1 atrial cells. In aged rabbit LA, pacing-induced atrial arrhythmias were dramatically increased and conduction velocity (CV) was significantly slower compared with young controls. Aged rabbit LA contained 120% more activated JNK and 54% less Cx43 than young LA. Young rabbits treated with JNK activator anisomycin also exhibited increased pacing-induced atrial arrhythmias and reduced Cx43 (by 34%), similar to that found in aged LA. In HL-1 cell cultures, anisomycin treatment for 16 h led to 42% reduction in Cx43, 24% reduction in CV, and an increased incidence of irregular rapid spontaneous activities. These effects were prevented by a specific JNK inhibitor, SP600125. Moreover, a 63% reduction in Cx43 after anisomycin treatment for 24 h led to further slowed CV (by 41%) along with dramatically increased irregular rapid spontaneous activity and highly discontinuous conduction. These JNK-induced functional abnormalities were completely reversed by overexpressed exogenous wild-type Cx43, but not by inactive Cx43.
  
  
  CONCLUSIONS
  JNK activation contributes to Cx43 reductions that promote development of AF. Modulation of JNK may be a potential novel therapeutic approach to prevent and treat AF.
authors.affiliation: Department of Medicine,  University of Alabama at Birmingham, Birmingham, AL,  USA.
authors.forename: Jiajie
authors.initials: J
authors.lastname: Yan
authors.forename: Wei
authors.initials: W
authors.lastname: Kong
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Eric C
authors.initials: EC
authors.lastname: Beyer
authors.forename: Gregory
authors.initials: G
authors.lastname: Walcott
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Fast
authors.forename: Xun
authors.initials: X
authors.lastname: Ai
mesh_terms: D000375:Aging / Q000378:metabolism / Q000473:pathology; D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D000873:Anthracenes / Q000494:pharmacology; D001145:Arrhythmias, Cardiac / Q000378:metabolism* / Q000503:physiopathology*; D001281:Atrial Fibrillation / Q000378:metabolism* / Q000503:physiopathology*; D002450:Cell Communication / Q000502:physiology; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006329:Heart Conduction System / Q000503:physiopathology; D066298:In Vitro Techniques; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008297:Male; D011817:Rabbits
chemical_list: D000873:Anthracenes; D018031:Connexin 43; D004791:Enzyme Inhibitors; C432165:pyrazolanthrone; D000841:Anisomycin; D048031:JNK Mitogen-Activated Protein Kinases