Genetic variation in GNB5 causes bradycardia by augmenting the cholinergic response via increased acetylcholine-activated potassium current (IK,ACh)

Research output: Contribution to journalResearch articleContributedpeer-review


  • Christiaan C. Veerman - , University of Amsterdam (Author)
  • Isabella Mengarelli - , University of Amsterdam (Author)
  • Charlotte D. Koopman - , Utrecht University, Netherlands Institute for Developmental Biology (Author)
  • Ronald Wilders - , University of Amsterdam (Author)
  • Shirley C. van Amersfoorth - , University of Amsterdam (Author)
  • Diane Bakker - , University of Amsterdam (Author)
  • Rianne Wolswinkel - , University of Amsterdam (Author)
  • Mariam Hababa - , Netherlands Institute for Developmental Biology (Author)
  • Teun P. de Boer - , Utrecht University (Author)
  • Kaomei Guan - , Institute of Pharmacology and Toxicology, Dresden University of Technology (Author)
  • James Milnes - , Xention Limited, Wellmera AG (Author)
  • Elisabeth M. Lodder - , University of Amsterdam (Author)
  • Jeroen Bakkers - , Utrecht University, Netherlands Institute for Developmental Biology (Author)
  • Arie O. Verkerk - , University of Amsterdam (Author)
  • Connie R. Bezzina - , University of Amsterdam (Author)


Mutations in GNB5, encoding the G-protein β5 subunit (Gβ5), have recently been linked to a multisystem disorder that includes severe bradycardia. Here, we investigated the mechanism underlying bradycardia caused by the recessive p.S81L Gβ5 variant. Using CRISPR/Cas9-based targeting, we generated an isogenic series of human induced pluripotent stem cell (hiPSC) lines that were either wild type, heterozygous or homozygous for the GNB5 p.S81L variant. These were differentiated into cardiomyocytes (hiPSC-CMs) that robustly expressed the acetylcholine-activated potassium channel [I(KACh); also known as IK,ACh]. Baseline electrophysiological properties of the lines did not differ. Upon application of carbachol (CCh), homozygous p.S81L hiPSC-CMs displayed an increased acetylcholine-activated potassium current (IK,ACh) density and a more pronounced decrease of spontaneous activity as compared to wild-type and heterozygous p.S81L hiPSC-CMs, explaining the bradycardia in homozygous carriers. Application of the specific I(KACh) blocker XEN-R0703 resulted in near-complete reversal of the phenotype. Our results provide mechanistic insights and proof of principle for potential therapy in patients carrying GNB5 mutations.


Original languageEnglish
Article numberdmm037994
JournalDMM Disease Models and Mechanisms
Issue number7
Publication statusPublished - 2019

External IDs

PubMed 31208990



  • Electrophysiology, I(KACh), Ion channels, Mechanisms, Membrane transport, Transgenic models, Treatment