PUBLICATION

A Functional Assay for Sick Sinus Syndrome Genetic Variants

Authors
Jou, C.J., Arrington, C.B., Barnett, S., Shen, J., Cho, S., Sheng, X., McCullagh, P.C., Bowles, N.E., Pribble, C.M., Saarel, E.V., Pilcher, T.A., Etheridge, S.P., Tristani-Firouzi, M.
ID
ZDB-PUB-170815-13
Date
2017
Source
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology   42: 2021-2029 (Journal)
Registered Authors
Keywords
Arrhythmia, Genetics, Sick sinus syndrome, Sudden cardiac death, Zebrafish
MeSH Terms
  • In Situ Hybridization
  • Patch-Clamp Techniques
  • Embryo, Nonmammalian/drug effects
  • Embryo, Nonmammalian/metabolism
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/antagonists & inhibitors
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/metabolism
  • Heart Rate/drug effects
  • Humans
  • Morpholinos/metabolism
  • Genotype
  • Sick Sinus Syndrome/genetics
  • Sick Sinus Syndrome/pathology*
  • Bradycardia/etiology
  • Heart/drug effects
  • Heart/physiology
  • Muscle Proteins/antagonists & inhibitors
  • Muscle Proteins/genetics
  • Muscle Proteins/metabolism
  • Potassium Channels/genetics
  • Potassium Channels/metabolism
  • Zebrafish/metabolism
  • Genetic Variation*
  • Animals
  • Phenotype
  • Pyrimidines/pharmacology
  • Mutation
  • Animals, Genetically Modified
PubMed
28803248 Full text @ Cell Physiol. Biochem.
Abstract
Congenital Sick Sinus Syndrome (SSS) is a disorder associated with sudden cardiac death due to severe bradycardia and prolonged pauses. Mutations in HCN4, the gene encoding inward Na+/K+ current (If), have been described as a cause of congenital SSS. The objective of this study is to develop an SSS model in embryonic zebrafish, and use zebrafish as a moderate-throughput assay to functionally characterize HCN4 variants.
To determine the function of hcn4 in zebrafish, embryos were either bathed in the If -specific blocker (ZD-7288), or endogenous hcn4 expression was knocked down using splice-blocking morpholinos. To assess whether the zebrafish model discriminates benign from pathogenic variants, we tested four HCN4 mutations known to cause human SSS and four variants of unknown significance (VUS).
Pharmacological blockade and knockdown of hcn4 in zebrafish phenocopied human SSS, displaying bradycardia and cardiac pauses in intact embryos and explanted hearts. The zebrafish assay correctly identified all disease-causing variants. Of the VUS, the assay predicted 2 as benign and 2 as hypomorphic variants.
We conclude that our embryonic zebrafish assay is a novel and effective tool to functionally characterize human HCN4 variants, which can be translated into important clinical prognostic information.
Genes / Markers
Figures
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Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping