PUBLICATION

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

Authors
Veerman, C.C., Mengarelli, I., Koopman, C.D., Wilders, R., van Amersfoorth, S.C., Bakker, D., Wolswinkel, R., Hababa, M., de Boer, T.P., Guan, K., Milnes, J., Lodder, E.M., Bakkers, J., Verkerk, A.O., Bezzina, C.R.
ID
ZDB-PUB-200506-20
Date
2019
Source
Disease models & mechanisms   12(7): (Journal)
Registered Authors
Bakkers, Jeroen
Keywords
Electrophysiology, I(KACh), Ion channels, Mechanisms, Membrane transport, Transgenic models, Treatment
MeSH Terms
  • Acetylcholine/pharmacology*
  • Animals
  • Bradycardia/genetics*
  • Bradycardia/therapy
  • GTP-Binding Protein beta Subunits/genetics*
  • Genetic Variation*
  • Humans
  • Induced Pluripotent Stem Cells/metabolism
  • Mutation
  • Patch-Clamp Techniques
  • Potassium Channels/drug effects*
  • Potassium Channels/physiology
  • Proof of Concept Study
  • Receptors, Cholinergic/physiology*
  • Zebrafish
PubMed
31208990 Full text @ Dis. Model. Mech.
Abstract
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.This article has an associated First Person interview with the first author of the paper.
Genes / Markers
Figures
Expression
Phenotype
Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping
Errata and Notes