Cardiomyocyte-specific overexpression of the ubiquitin ligase Wwp1 contributes to reduction in Connexin 43 and arrhythmogenesis

• Published in: Journal of molecular and cellular cardiology Vol. 88; pp. 1 - 13
• Main Authors: Basheer, Wassim A., Harris, Brett S., Mentrup, Heather L., Abreha, Measho, Thames, Elizabeth L., Lea, Jessica B., Swing, Deborah A., Copeland, Neal G., Jenkins, Nancy A., Price, Robert L., Matesic, Lydia E.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2015
• Subjects: Actins - genetics; Actins - metabolism; Animals; Arrhythmias, Cardiac - genetics; Arrhythmias, Cardiac - metabolism; Arrhythmias, Cardiac - pathology; Arrhythmogenesis; Cardiovascular; Connexin; Connexin 43 - genetics; Connexin 43 - metabolism; Disease Models, Animal; Female; Gap junction; Gap Junctions - metabolism; Gap Junctions - pathology; Gene Expression Regulation; Heart Ventricles - metabolism; Heart Ventricles - pathology; Hypertrophy, Left Ventricular - genetics; Hypertrophy, Left Ventricular - metabolism; Hypertrophy, Left Ventricular - pathology; Male; Mice; Mice, Transgenic; Myocardium - metabolism; Myocardium - pathology; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - pathology; Phenotype; Promoter Regions, Genetic; Proteasome Endopeptidase Complex - metabolism; Protein Stability; Proteolysis; Signal Transduction; Ubiquitin; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Ubiquitination; Wwp1; Ubiquitin; GJ; PMA; Wwp1; Arrhythmogenesis; E1; E2; Ub; E3; Gap junction; HECT; WGA; ODDD; Connexin; Cx43; RING; HA; WT; Tmx; LVH; ubiquitin ligase; hemagglutinin; oculodentodigital dysplasia; phorbol 12-myristate 13-acetate; Connexin 43; wheat germ agglutinin; tamoxifen; gap junctions; ubiquitin activating enzyme; ubiquitin; homologous to E6-AP carboxy terminus; really interesting new gene; left ventricular hypertrophy; wild type; ubiquitin conjugating enzyme
• ISSN: 0022-2828; 1095-8584; 1095-8584
• DOI: 10.1016/j.yjmcc.2015.09.004

Gap junctions (GJ) are intercellular channels composed of connexin subunits that play a critical role in a diverse number of cellular processes in all tissue types. In the heart, GJs mediate electrical coupling between cardiomyocytes and display mislocalization and/or downregulation in cardiac disease (a process known as GJ remodeling), producing an arrhythmogenic substrate. The main constituent of GJs in the ventricular myocardium is Connexin 43 (Cx43), an integral membrane protein that is rapidly turned over and shows decreased expression or function with age. We hypothesized that Wwp1, an ubiquitin ligase whose expression in known to increase in aging-related pathologies, may regulate Cx43 in vivo by targeting it for ubiquitylation and degradation and yield tissue-specific Cx43 loss of function phenotypes. When Wwp1 was globally overexpressed in mice under the control of a β-actin promoter, the highest induction of Wwp1 expression was observed in the heart which was associated with a 90% reduction in cardiac Cx43 protein levels, left ventricular hypertrophy (LVH), and the development of lethal ventricular arrhythmias around 8weeks of age. This phenotype was completely penetrant in two independent founder lines. Cardiomyocyte-specific overexpression of Wwp1 confirmed that this phenotype was cell autonomous and delineated Cx43-dependent and –independent roles for Wwp1 in arrhythmogenesis and LVH, respectively. Using a cell-based system, it was determined that Wwp1 co-immunoprecipitates with and ubiquitylates Cx43, causing a decrease in the steady state levels of Cx43 protein. These findings offer new mechanistic insights into the regulation of Cx43 which may be exploitable in various gap junctionopathies. •Overexpression of the ubiquitin ligase Wwp1 yields sudden cardiac death in mouse.•Chronic overexpression of Wwp1 promotes left ventricular hypertrophy.•The effects of Wwp1 are cardiomyocyte cell autonomous.•Wwp1 associates with and ubiquitylates connexin 43 contributing to arrhythmogenesis.