Canonical wnt signaling regulates atrioventricular junction programming and electrophysiological properties

Circ Res. 2015 Jan 30;116(3):398-406. doi: 10.1161/CIRCRESAHA.116.304731. Epub 2014 Nov 6.


Rationale: Proper patterning of the atrioventricular canal (AVC) is essential for delay of electrical impulses between atria and ventricles, and defects in AVC maturation can result in congenital heart disease.

Objective: To determine the role of canonical Wnt signaling in the myocardium during AVC development.

Methods and results: We used a novel allele of β-catenin that preserves β-catenin's cell adhesive functions but disrupts canonical Wnt signaling, allowing us to probe the effects of Wnt loss of function independently. We show that the loss of canonical Wnt signaling in the myocardium results in tricuspid atresia with hypoplastic right ventricle associated with the loss of AVC myocardium. In contrast, ectopic activation of Wnt signaling was sufficient to induce formation of ectopic AV junction-like tissue as assessed by morphology, gene expression, and electrophysiological criteria. Aberrant AVC development can lead to ventricular pre-excitation, a characteristic feature of Wolff-Parkinson-White syndrome. We demonstrate that postnatal activation of Notch signaling downregulates canonical Wnt targets within the AV junction. Stabilization of β-catenin protein levels can rescue Notch-mediated ventricular pre-excitation and dysregulated ion channel gene expression.

Conclusions: Our data demonstrate that myocardial canonical Wnt signaling is an important regulator of AVC maturation and electric programming upstream of Tbx3. Our data further suggest that ventricular pre-excitation may require both morphological patterning defects, as well as myocardial lineage reprogramming, to allow robust conduction across accessory pathway tissue.

Keywords: Notch signaling pathway; Wnt signaling pathway; arrhythmias, cardiac; arrhythmogenic cardiomyopathy; septal defects; tricuspid atresia; ventricular pre-excitation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Heart Atria / embryology
  • Heart Atria / metabolism*
  • Heart Atria / physiopathology
  • Heart Conduction System / embryology
  • Heart Conduction System / metabolism*
  • Heart Conduction System / physiopathology
  • Heart Ventricles / embryology
  • Heart Ventricles / metabolism*
  • Heart Ventricles / physiopathology
  • Mice
  • Myocardium / metabolism
  • Receptors, Notch / metabolism
  • T-Box Domain Proteins / metabolism
  • Tricuspid Atresia / genetics
  • Tricuspid Atresia / metabolism*
  • Tricuspid Atresia / physiopathology
  • Wnt Signaling Pathway*
  • beta Catenin / genetics
  • beta Catenin / metabolism*


  • CTNNB1 protein, mouse
  • Receptors, Notch
  • T-Box Domain Proteins
  • Tbx3 protein, mouse
  • beta Catenin