title: N-cadherin haploinsufficiency affects cardiac gap junctions and arrhythmic susceptibility.
abstract: Cardiac-specific deletion of the murine gene (Cdh2) encoding the cell adhesion molecule, N-cadherin, results in disassembly of the intercalated disc (ICD) structure and sudden arrhythmic death. Connexin 43 (Cx43)-containing gap junctions are significantly reduced in the heart after depleting N-cadherin, therefore we hypothesized that animals expressing half the normal levels of N-cadherin would exhibit an intermediate phenotype. We examined the effect of N-cadherin haploinsufficiency on Cx43 expression and susceptibility to induced arrhythmias in mice either wild-type or heterozygous for the Cx43 (Gja1)-null allele. An increase in hypophosphorylated Cx43 accompanied by a modest decrease in total Cx43 protein levels was observed in the N-cadherin heterozygous mice. Consistent with these findings N-cadherin heterozygotes exhibited increased susceptibility to ventricular arrhythmias compared to wild-type mice. Quantitative immunofluorescence microscopy revealed a reduction in size of large Cx43-containing plaques in the N-cadherin heterozygous animals compared to wild-type. Gap junctions were further decreased in number and size in the N-cad/Cx43 compound heterozygous mice with increased arrhythmic susceptibility compared to the single mutants. The scaffold protein, ZO-1, was reduced at the ICD in N-cadherin heterozygous cardiomyocytes providing a possible explanation for the reduction in Cx43 plaque size. These data provide further support for the intimate relationship between N-cadherin and Cx43 in the heart, and suggest that germline mutations in the human N-cadherin (Cdh2) gene may predispose patients to increased risk of cardiac arrhythmias.
authors.affiliation: Center for Research on Reproduction and Women's Health, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors.forename: Jifen
authors.initials: J
authors.lastname: Li
authors.forename: Mark D
authors.initials: MD
authors.lastname: Levin
authors.forename: Yanming
authors.initials: Y
authors.lastname: Xiong
authors.forename: Nataliya
authors.initials: N
authors.lastname: Petrenko
authors.forename: Vickas V
authors.initials: VV
authors.lastname: Patel
authors.forename: Glenn L
authors.initials: GL
authors.lastname: Radice
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002450:Cell Communication / Q000235:genetics; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D004594:Electrophysiology; D005455:Fluorescent Antibody Technique; D017629:Gap Junctions / Q000378:metabolism*; D006579:Heterozygote; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D032342:Muscle Cells / Q000378:metabolism; D009154:Mutation; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010750:Phosphoproteins / Q000378:metabolism; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin / Q000378:metabolism
chemical_list: D015820:Cadherins; D018031:Connexin 43; D008565:Membrane Proteins; D010750:Phosphoproteins; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin