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Vad OB, Yan Y, Denti F, Ahlberg G, Refsgaard L, Bomholtz SH, Santos JL, Rasmussen S, Haunsø S, Svendsen JH, Christophersen IE, Schmitt N, Olesen MS, Bentzen BH. Whole-Exome Sequencing Implicates Neuronal Calcium Channel with Familial Atrial Fibrillation. Front Genet 2022; 13:806429. [PMID: 35154276 PMCID: PMC8832975 DOI: 10.3389/fgene.2022.806429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/03/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Atrial Fibrillation (AF) is the most prevalent sustained cardiac arrhythmia, responsible for considerable morbidity and mortality. The heterogenic and complex pathogenesis of AF remains poorly understood, which contributes to the current limitation in effective treatments. We aimed to identify rare genetic variants associated with AF in patients with familial AF. Methods and results: We performed whole exome sequencing in a large family with familial AF and identified a rare variant in the gene CACNA1A c.5053G > A which co-segregated with AF. The gene encodes for the protein variants CaV2.1-V1686M, and is important in neuronal function. Functional characterization of the CACNA1A, using patch-clamp recordings on transiently transfected mammalian cells, revealed a modest loss-of-function of CaV2.1-V1686M. Conclusion: We identified a rare loss-of-function variant associated with AF in a gene previously linked with neuronal function. The results allude to a novel link between dysfunction of an ion channel previously associated with neuronal functions and increased risk of developing AF.
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Affiliation(s)
- Oliver Bundgaard Vad
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Yannan Yan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Federico Denti
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gustav Ahlberg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lena Refsgaard
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Sofia Hammami Bomholtz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joana Larupa Santos
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simon Rasmussen
- Disease Systems Biology Program, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Jesper Hastrup Svendsen
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ingrid Elizabeth Christophersen
- The Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
- Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Rud, Norway
| | - Nicole Schmitt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Salling Olesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- *Correspondence: Morten Salling Olesen,
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Modified autonomic regulation in mice mutated in the β4 subunit of the lh/lh calcium channel. Biochem Biophys Res Commun 2015; 461:200-5. [PMID: 25892515 DOI: 10.1016/j.bbrc.2015.03.112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 03/22/2015] [Indexed: 11/23/2022]
Abstract
Genetic analyses have revealed an important association between P/Q-type calcium channel activities and hereditary neurological disorders. The P/Q-type channels are composed principally of heterologous multimeric subunits including CaV2.1 and CaVβ4. Of these, the β4 subunit is thought to play a significant role in channel physiology, because a mouse line mutant in that subunit (the lethargic mouse: lh) exhibits a severe ataxic phenotype. The aim of the present study was to elucidate the physiological importance of the β4 subunit. ECG analysis showed that the T wave was high in 8-week-old lh mutants; this may be associated with hyperkalemia. Upon pharmacological ECG analysis, 2-3-week-old lh mutants exhibited reduced responses to a β-blocker and a muscarinic receptor antagonist. Analysis of heart rate variability revealed that the R-R interval was unstable in lh mutants and that both the low- and high-frequency components had increased in extent, indicating that the tonus of both the sympathetic and parasympathetic nervous systems was modified. Thus, our present study revealed that the β4 subunit played a significant role in regulation of sympathetic and parasympathetic nerve activities.
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Yoshimoto T, Aoyama Y, Kim TY, Niimi K, Takahashi E, Itakura C. Rolling Nagoya mouse strain (PROD-rol/rol) with classic piebald mutation. J Vet Med Sci 2014; 76:1093-8. [PMID: 24758835 PMCID: PMC4155188 DOI: 10.1292/jvms.14-0096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Ataxic
rolling Nagoya (PROD-rol/rol) mice,
which carry a mutation in the α1 subunit of the Cav2.1 channel
(Cacna1a) gene, were discovered in 1969. They show white spots on
agouti coat and have a mutation in the piebald spotting (s) locus.
However, mutation analysis of the s locus encoding the endothelin
receptor type B (Ednrb) gene in
PROD-rol/rol mice had not been performed. Here, we
examined the genomic and mRNA sequences of the Ednrb gene in
PROD-rol/rol and wild-type rolling
Nagoya (PROD-s/s) and studied the expression patterns of
Ednrb and Cacna1a genes in these mice in comparison
with C57BL/6J mice. Polymerase chain reaction analyses revealed two silent nucleotide
substitutions in the coding region and insertion of a retroposon-like element in intron 1
of the Ednrb gene. Expression analyses demonstrated similar localizations
and levels of Ednrb and Cacna1a expression in the colon
between PROD-rol/rol and
PROD-s/s mice, but the expression levels of both genes
were diminished compared with C57BL/6J mice. Microsatellite genotyping showed that at
least particular regions of chromosome 14 proximal to the Ednrb locus of
the PROD strain were derived from Japanese fancy piebald mice. These results indicated
that PROD-rol/rol mice have two mutant genes,
Ednrb and Cacna1a. As no PROD strain had an intact
Ednrb gene, using congenic rolling mice would better serve to examine
rolling Nagoya-type Cav2.1 channel dysfunctions.
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Affiliation(s)
- Takuro Yoshimoto
- Research Resources Center, RIKEN Brain Science Institute, Saitama 351-0198, Japan
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Kv1.1 potassium channel deficiency reveals brain-driven cardiac dysfunction as a candidate mechanism for sudden unexplained death in epilepsy. J Neurosci 2010; 30:5167-75. [PMID: 20392939 DOI: 10.1523/jneurosci.5591-09.2010] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Mice lacking Kv1.1 Shaker-like potassium channels encoded by the Kcna1 gene exhibit severe seizures and die prematurely. The channel is widely expressed in brain but only minimally, if at all, in mouse myocardium. To test whether Kv1.1-potassium deficiency could underlie primary neurogenic cardiac dysfunction, we performed simultaneous video EEG-ECG recordings and found that Kcna1-null mice display potentially malignant interictal cardiac abnormalities, including a fivefold increase in atrioventricular (AV) conduction blocks, as well as bradycardia and premature ventricular contractions. During seizures the occurrence of AV conduction blocks increased, predisposing Kv1.1-deficient mice to sudden unexplained death in epilepsy (SUDEP), which we recorded fortuitously in one animal. To determine whether the interictal AV conduction blocks were of cardiac or neural origin, we examined their response to selective pharmacological blockade of the autonomic nervous system. Simultaneous administration of atropine and propranolol to block parasympathetic and sympathetic branches, respectively, eliminated conduction blocks. When administered separately, only atropine ameliorated AV conduction blocks, indicating that excessive parasympathetic tone contributes to the neurocardiac defect. We found no changes in Kv1.1-deficient cardiac structure, but extensive Kv1.1 expression in juxtaparanodes of the wild-type vagus nerve, the primary source of parasympathetic input to the heart, suggesting a novel site of action leading to Kv1.1-associated cardiac bradyarrhythmias. Together, our data suggest that Kv1.1 deficiency leads to impaired neural control of cardiac rhythmicity due in part to aberrant parasympathetic neurotransmission, making Kcna1 a strong candidate gene for human SUDEP.
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