Targeting the RyR2 to Prevent Atrial Fibrillation.
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ABSTRACT:
SUBMITTER: Gillis AM
PROVIDER: S-EPMC9592734 | biostudies-literature | 2022 Oct
REPOSITORIES: biostudies-literature
Publications
Targeting the RyR2 to Prevent Atrial Fibrillation.
Gillis Anne M AM Dobrev Dobromir D
Circulation. Arrhythmia and electrophysiology 20220930 10
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Project description:Background. Atrial fibrillation (AF) is a common arrhythmia in elderly patients and is associated with increased risk of mortality. The pathogenesis of AF is complex and based on multiple genetic and environmental factors. Genome-wide association studies identified several loci in AF patients, indicating the complex genetic architecture of this disease. In rare cases, familial forms of AF have been described. Today, pathogenic variants in at least 11 different genes are associated with monogenic AF. Case presentation. The 37-year-old male patient presented to our emergency department with AF. At the age of 35, he had already been diagnosed with paroxysmal AF. Additionally, his 34-year-old brother had also been diagnosed with AF as well as nonobstructive hypertrophic cardiomyopathy. Moreover, the patient's father was diagnosed with AF in his twenties. Transthoracic echocardiography and cardiac MRI revealed a reduced systolic left ventricular ejection without any signs of hypertrophic cardiomyopathy. Genetic testing identified the heterozygous missense variants c.3371C > T, p.(Pro1124Leu) in RYR2 (NM_001035.3) and c.2524C > A, p.(Pro842Thr) in HCN4 (NM_005477.3) in the patient's and his brother's DNA. Discussion. This case of familial AF helps to strengthen the role of RYR2 as a disease gene in the context of AF. Although the variant in RYR2 needs to be classified formally as variant of unknown significance, we regard it as probably disease-causing due to the previously published data. As RYR2 has already been identified as a possible target for prevention and therapy of AF, the knowledge of variants in RYR2 might become even more crucial for individual molecular therapies in the future.
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| S-EPMC7252716 | biostudies-literature
Project description:ObjectivesThis study sought to study the role of junctophilin-2 (JPH2) in atrial fibrillation (AF).BackgroundJPH2 is believed to have an important role in sarcoplasmic reticulum (SR) Ca(2+) handling and modulation of ryanodine receptor Ca(2+) channels (RyR2). Whereas defective RyR2-mediated Ca(2+) release contributes to the pathogenesis of AF, nothing is known about the potential role of JPH2 in atrial arrhythmias.MethodsScreening 203 unrelated hypertrophic cardiomyopathy patients uncovered a novel JPH2 missense mutation (E169K) in 2 patients with juvenile-onset paroxysmal AF (pAF). Pseudoknock-in (PKI) mouse models were generated to determine the molecular defects underlying the development of AF caused by this JPH2 mutation.ResultsPKI mice expressing E169K mutant JPH2 exhibited a higher incidence of inducible AF than wild type (WT)-PKI mice, whereas A399S-PKI mice expressing a hypertrophic cardiomyopathy-linked JPH2 mutation not associated with atrial arrhythmias were not significantly different from WT-PKI. E169K-PKI but not A399A-PKI atrial cardiomyocytes showed an increased incidence of abnormal SR Ca(2+) release events. These changes were attributed to reduced binding of E169K-JPH2 to RyR2. Atrial JPH2 levels in WT-JPH2 transgenic, nontransgenic, and JPH2 knockdown mice correlated negatively with the incidence of pacing-induced AF. Ca(2+) spark frequency in atrial myocytes and the open probability of single RyR2 channels from JPH2 knockdown mice was significantly reduced by a small JPH2-mimicking oligopeptide. Moreover, patients with pAF had reduced atrial JPH2 levels per RyR2 channel compared to sinus rhythm patients and an increased frequency of spontaneous Ca(2+) release events.ConclusionsOur data suggest a novel mechanism by which reduced JPH2-mediated stabilization of RyR2 due to loss-of-function mutation or reduced JPH2/RyR2 ratios can promote SR Ca(2+) leak and atrial arrhythmias, representing a potential novel therapeutic target for AF.
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2019-10-07 | GSE138530 | GEO
Project description:Transcriptional profiling to assess atrial gene expression in atrial LKB1 KO vs. AMPK KO vs. WT mice.
2022-04-05 | GSE200144 | GEO
Project description:Abnormal calcium release from sarcoplasmic reticulum (SR) is considered an important trigger of atrial fibrillation (AF). Whereas increased Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activity has been proposed to contribute to SR leak and AF induction, downstream targets of CaMKII remain controversial.To test the hypothesis that inhibition of CaMKII-phosphorylated type-2 ryanodine receptors (RyR2) prevents AF initiation in FKBP12.6-deficient (-/-) mice.Mice lacking RyR2-stabilizing subunit FKBP12.6 had a higher incidence of spontaneous and pacing-induced AF compared with wild-type mice. Atrial myocytes from FKBP12.6-/- mice exhibited spontaneous Ca(2+) waves (SCaWs) leading to Na(+)/Ca(2+)-exchanger activation and delayed afterdepolarizations (DADs). Mutation S2814A in RyR2, which inhibits CaMKII phosphorylation, reduced Ca(2+) spark frequency, SR Ca(2+) leak, and DADs in atrial myocytes from FKBP12.6-/-:S2814A mice compared with FKBP12.6-/- mice. Moreover, FKBP12.6-/-:S2814A mice exhibited a reduced susceptibility to inducible AF, whereas FKBP12.6-/-:S2808A mice were not protected from AF.FKBP12.6 mice exhibit AF caused by SR Ca(2+) leak, Na(+)/Ca(2+)-exchanger activation, and DADs, which promote triggered activity. Genetic inhibition of RyR2-S2814 phosphorylation prevents AF induction in FKBP12.6-/- mice by suppressing SR Ca(2+) leak and DADs. These results suggest suppression of RyR2-S2814 phosphorylation as a potential anti-AF therapeutic target.
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Project description:Genome-wide association studies (GWAS) have found that increased risk for atrial fibrillation (AF), the most common type of arrhythmia in humans, is associated with non-coding sequence variants located in proximity to the PITX2 homeobox gene. Using cardiomyocyte-specific epigenomic and comparative genomic analyses, we identified two AF-associated enhancers neighboring PITX2 with varying degrees of conservation in mice. Pitx2c promoter directly contacted the AF-associated enhancer regions. CRISPR/Cas9 mediated deletion of a 20 kb long topologically engaged enhancer lead to reduced Pitx2c transcription and AF predisposition. Allele-specific ChIP-seq and CUT&RUN experiments showed that long-range interaction of this AF-associated region with the Pitx2c promoter was required for maintenance of the Pitx2c promoter chromatin state. Moreover, long-range looping was mediated by CTCF, as the genetic disruption of an intronic CTCF binding site caused decreased Pitx2c cardiac expression, AF predisposition, and reduced active chromatin marks on Pitx2. Our findings reveal that AF risk variants located at 4q25 reside in genomic regions possessing long-range transcriptional regulatory functions directed at PITX2
2019-10-08 | GSE138529 | GEO
Project description:Genome-wide association studies (GWAS) have found that increased risk for atrial fibrillation (AF), the most common type of arrhythmia in humans, is associated with non-coding sequence variants located in proximity to the PITX2 homeobox gene. Using cardiomyocyte-specific epigenomic and comparative genomic analyses, we identified two AF-associated enhancers neighboring PITX2 with varying degrees of conservation in mice. Pitx2c promoter directly contacted the AF-associated enhancer regions. CRISPR/Cas9 mediated deletion of a 20 kb long topologically engaged enhancer lead to reduced Pitx2c transcription and AF predisposition. Allele-specific ChIP-seq and CUT&RUN experiments showed that long-range interaction of this AF-associated region with the Pitx2c promoter was required for maintenance of the Pitx2c promoter chromatin state. Moreover, long-range looping was mediated by CTCF, as the genetic disruption of an intronic CTCF binding site caused decreased Pitx2c cardiac expression, AF predisposition, and reduced active chromatin marks on Pitx2. Our findings reveal that AF risk variants located at 4q25 reside in genomic regions possessing long-range transcriptional regulatory functions directed at PITX2
2019-10-08 | GSE138528 | GEO
Project description: Not available
| S-EPMC9345967 | biostudies-literature