title: Connexin45 provides optimal atrioventricular nodal conduction in the adult mouse heart.
abstract: BACKGROUND
  The gap junctional protein connexin (Cx) 45 is strongly expressed in the early embryonic myocardium. In the adult hearts of mice and humans, the expression mainly is restricted to the cardiac conduction system. Cx45 plays an essential role for development and function of the embryonic heart because general and cardiomyocyte-directed deficiencies of Cx45 in mice lead to embryonic lethality attributable to morphological and functional cardiovascular defects. The function of Cx45 in the adult mouse has not yet been cleared.
  
  
  OBJECTIVE
  To clarify the function of Cx45 in the adult mouse heart.
  
  
  RESULTS
  To circumvent the embryonic lethality resulting from Cx45 deficiency, mice were generated in which deletion of Cx45 specifically was induced in cardiomyocytes of adult mice. These Cx45-deficient mice were viable but showed a decrease in atrioventricular nodal conductivity. In addition, the Cx30.2 protein that is coexpressed with Cx45 in the cardiac conduction system was posttranscriptionally reduced by 70% in mutant hearts. Furthermore, deletion of both Cx45 and Cx30.2 resulted in viable mice that, however, showed stronger impairment of atrioventricular nodal conduction than the single Cx45-deficient mice.
  
  
  CONCLUSIONS
  Cx45 is required for optimal impulse propagation in the atrioventricular node and stabilizes the level of the coexpressed Cx30.2 protein in the adult mouse heart. In contrast to the embryo, Cx45 is not essential for the viability of adult mice.
authors.affiliation: LIMES-Institute, Molecular Genetics, University of Bonn, Bonn, Germany.
authors.forename: Marina
authors.initials: M
authors.lastname: Frank
authors.forename: Angela
authors.initials: A
authors.lastname: Wirth
authors.forename: René P
authors.initials: RP
authors.lastname: Andrié
authors.forename: Maria M
authors.initials: MM
authors.lastname: Kreuzberg
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Dobrowolski
authors.forename: Gerald
authors.initials: G
authors.lastname: Seifert
authors.forename: Stefan
authors.initials: S
authors.lastname: Offermanns
authors.forename: Georg
authors.initials: G
authors.lastname: Nickenig
authors.forename: Klaus
authors.initials: K
authors.lastname: Willecke
authors.forename: Jan W
authors.initials: JW
authors.lastname: Schrickel
mesh_terms: D000818:Animals; D001283:Atrioventricular Node / Q000196:embryology* / Q000378:metabolism*; D017630:Connexins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D006321:Heart / Q000196:embryology* / Q000502:physiology*; D006329:Heart Conduction System / Q000196:embryology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout
chemical_list: D017630:Connexins; C082920:connexin 45