Journal
CARDIOVASCULAR RESEARCH
Volume 111, Issue 3, Pages 274-286Publisher
OXFORD UNIV PRESS
DOI: 10.1093/cvr/cvw083
Keywords
Desmosome; Sinus node dysfunction; Physiology; function; Arrhythmia (mechanisms); Heart rate variability
Categories
Funding
- National Institutes of Health [P30 NS04710]
- NIH from NHLBI
- NIH from NIGMS
- American Heart Association
- NIH T32 training grant
- NIH/NHLBI
- Saving tiny Heart Society
- California Institute of Regenerative Medicine and Tobacco Related Disease Research Program
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Current mechanisms driving cardiac pacemaker function have focused on ion channel and gap junction channel function, which are essential for action potential generation and propagation between pacemaker cells. However, pacemaker cells also harbour desmosomes that structurally anchor pacemaker cells to each other in tissue, but their role in pacemaker function remains unknown. To determine the role of desmosomes in pacemaker function, we generated a novel mouse model harbouring cardiac conduction-specific ablation (csKO) of the central desmosomal protein, desmoplakin (DSP) using the Hcn4-Cre-ERT2 mouse line. Hcn4-Cre targets cells of the adult mouse sinoatrial node (SAN) and can ablate DSP expression in the adult DSP csKO SAN resulting in specific loss of desmosomal proteins and structures. Dysregulation of DSP via loss-of-function (adult DSP csKO mice) and mutation (clinical case of a patient harbouring a pathogenic DSP variant) in mice and man, respectively, revealed that desmosomal dysregulation is associated with a primary phenotype of increased sinus pauses/dysfunction in the absence of cardiomyopathy. Underlying defects in beat-to-beat regulation were also observed in DSP csKO mice in vivo and intact atria ex vivo. DSP csKO SAN exhibited migrating lead pacemaker sites associated with connexin 45 loss. In vitro studies exploiting ventricular cardiomyocytes that harbour DSP loss and concurrent early connexin loss phenocopied the loss of beat-to-beat regulation observed in DSP csKO mice and atria, extending the importance of DSP-associated mechanisms in driving beat-to-beat regulation of working cardiomyocytes. We provide evidence of a mechanism that implicates an essential role for desmosomes in cardiac pacemaker function, which has broad implications in better understanding mechanisms underlying beat-to-beat regulation as well as sinus node disease and dysfunction.
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