Overexpression of SCN5A in mouse heart mimics human syndrome of enhanced atrioventricular nodal conduction

Liu, Gong Xin; Remme, Carol Ann; Boukens, Bastiaan J.; Belardinelli, Luiz; Rajamani, Sridharan

doi:10.1016/j.hrthm.2015.01.029

Cited by 11 publications

(12 citation statements)

References 22 publications

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“…Overexpression of SCN5A in transgenic mice has been shown to shorten P wave duration and PR interval, while QRS and QT intervals remained unchanged (Zhang et al, 2007). This was consistent with the observation that mice overexpressing SCN5A exhibit accelerated atrioventricular, atrial, and ventricular conduction (Liu et al, 2015). It was therefore not surprising to record an increase of the P wave duration and the PR interval, even if not significant, in our model of overexpression of a dominant-negative Na v 1.5 mutation.…”

Section: Comparison With Other Animal Models Of Brugada Syndromesupporting

confidence: 90%

In vivo Dominant-Negative Effect of an SCN5A Brugada Syndrome Variant

et al. 2021

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Loss-of-function mutations in the cardiac Na+ channel α-subunit Nav1.5, encoded by SCN5A, cause Brugada syndrome (BrS), a hereditary disease characterized by sudden cardiac death due to ventricular fibrillation. We previously evidenced in vitro the dominant-negative effect of the BrS Nav1.5-R104W variant, inducing retention of wild-type (WT) channels and leading to a drastic reduction of the resulting Na+ current (INa). To explore this dominant-negative effect in vivo, we created a murine model using adeno-associated viruses (AAVs).MethodsDue to the large size of SCN5A, a dual AAV vector strategy was used combining viral DNA recombination and trans-splicing. Mice were injected with two AAV serotypes capsid 9: one packaging the cardiac specific troponin-T promoter, the 5′ half of hSCN5A cDNA, a splicing donor site and a recombinogenic sequence; and another packaging the complementary recombinogenic sequence, a splicing acceptor site, the 3′ half of hSCN5A cDNA fused to the gfp gene sequence, and the SV40 polyA signal. Eight weeks after AAV systemic injection in wild-type (WT) mice, echocardiography and ECG were recorded and mice were sacrificed. The full-length hSCN5A-gfp expression was assessed by western blot and immunohistochemistry in transduced heart tissues and the Na+ current was recorded by the patch-clamp technique in isolated adult GFP-expressing heart cells.ResultsAlmost 75% of the cardiomyocytes were transduced in hearts of mice injected with hNav1.5 and ∼30% in hNav1.5-R104W overexpressing tissues. In ventricular mice cardiomyocytes expressing R104W mutant channels, the endogenous INa was significantly decreased. Moreover, overexpression of R104W channels in normal hearts led to a decrease of total Nav1.5 expression. The R104W mutant also induced a slight dilatation of mice left ventricles and a prolongation of RR interval and P-wave duration in transduced mice. Altogether, our results demonstrated an in vivo dominant-negative effect of defective R104W channels on endogenous ones.ConclusionUsing a trans-splicing and viral DNA recombination strategy to overexpress the Na+ channel in mouse hearts allowed us to demonstrate in vivo the dominant-negative effect of a BrS variant identified in the N-terminus of Nav1.5.

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Section: Comparison With Other Animal Models Of Brugada Syndromesupporting

confidence: 90%

In vivo Dominant-Negative Effect of an SCN5A Brugada Syndrome Variant

et al. 2021

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“…Mutations in SCN5A, the cardiac sodium channel gene, underlie hereditary cardiac arrhythmic syndromes, such as type 3 LQTS (6). Scn5a heterozygous mice display lengthening of the PR interval, whereas mice that overexpress Scn5a in the heart experience shortening of the PR interval, suggesting that the expression level of Scn5a is a determinant of the length of the PR interval on ECGs (31,57). We did not include PR interval in the averaged analysis because of a gross irregularity in PR interval (Supplemental Fig.…”

Section: Discussionmentioning

confidence: 99%

Cardiac-specific inactivation of Prdm16 effects cardiac conduction abnormalities and cardiomyopathy-associated phenotypes

Nam

Lim

et al. 2020

American Journal of Physiology-Heart and Circulatory Physiology

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A variant in the PRDM16 locus has been correlated with QRS duration in an electrocardiogram genome-wide association study, and the deletion of PRDM16 has been implicated as a causal factor of the dilated cardiomyopathy that is linked to 1p36 deletion syndrome. We aimed to determine how a null mutation of Prdm16 affects cardiac function and study the underlying mechanism of the resulting phenotype in an appropriate mouse model. We used cardiac-specific Prdm16 conditional knockout mice to examine cardiac function by electrocardiography. QRS duration and QTc interval increased significantly in cardiac-specific Prdm16 knockout animals compared with wild-type mice. Further, we assessed cardiomyopathy-associated features by trichrome staining, densitometry, and hydroxyproline assay. Prdm16-null hearts showed greater fibrosis and cardiomyocyte hypertrophy. By quantitative real-time PCR, Prdm16-null hearts upregulated extracellular matrix-related genes ( Ctgf, Timp1) and α-smooth muscle actin ( Acta2), a myofibroblast marker. Moreover, TGF-β signaling was activated in Prdm16-null hearts, as evidenced by increased Tgfb1–3 transcript levels and phosphorylated Smad2. However, the inhibition of TGF-β receptor did not reverse the aberrations in conduction in cardiac-specific Prdm16 knockout mice. To determine the underlying mechanisms, we performed RNA-seq using mouse left ventricular tissue. By functional analysis, Prdm16-null hearts experienced dysregulated expression of ion channel genes, including Kcne1, Scn5a, Cacna1h, and Cacna2d2. Mice with Prdm16-null hearts develop abnormalities in cardiac conduction and cardiomyopathy-associated phenotypes, including fibrosis and cellular hypertrophy. Further, the RNA-seq findings suggest that impairments in ion homeostasis (Ca2+, K+, and Na+) may at least partially underlie the abnormal conduction in cardiac-specific Prdm16 knockout mice. NEW & NOTEWORTHY This is the first study that describes aberrant cardiac function and cardiomyopathy-associated phenotypes in an appropriate murine genetic model with cardiomyocyte-specific Prdm16-null mutation. It is noteworthy that the correlation of PRDM16 with QRS duration is replicated in a murine animal model and the potential underlying mechanism may be the impairment of ion homeostasis.

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“…Deletions, and gain- or loss-of-function mutations in SCN5A are associated with a spectrum of human cardiac conduction traits and diseases including QRS duration, PR interval, bradycardia, atrial fibrillation, and Brugada syndrome (Daimi et al, 2019; Li et al, 2018). Precise expression of SCN5A in cardiomyocytes is required for normal heart conduction, and mice with higher levels of SCN5A show changes in heart conduction (Liu et al, 2015; Zhang et al, 2007). The putative SCN5A fetal heart enhancer contains a cluster of low-affinity sites ranging from 0.09 – 0.25 relative binding affinity (Figure 6B).…”

Section: Resultsmentioning

confidence: 99%

“…Both gain- and loss-of-function variants within the coding region of SCN5A, and a noncoding variant, lead to changes in SCN5A function and subsequently heart conduction (Li et al, 2018; Veerman et al, 2015). Overexpression of SCN5A in mice leads to changes in heart conduction (Liu et al, 2015; Zhang et al, 2007). We identify a variant associated with QRS duration within an SCN5A enhancer that leads to an 8-fold increase in ETS binding affinity and a significant increase in expression when tested in human iPSC-derived cardiomyocytes (iPSC-CMs) (Figure 6).…”

Section: Introductionmentioning

confidence: 99%

Affinity-optimizing variants within cardiac enhancers disrupt heart development and contribute to cardiac traits

Jindal

Bantle

Solvason

et al. 2022

Preprint

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SummaryEnhancers direct precise gene expression patterns during development and harbor the majority of variants associated with disease. We find that suboptimal affinity ETS transcription factor binding sites are prevalent within Ciona and human developmental heart enhancers. Here we demonstrate in two diverse systems, Ciona intestinalis and human iPSC-derived cardiomyocytes (iPSC-CMs), that single nucleotide changes can optimize the affinity of ETS binding sites, leading to gain-of-function gene expression associated with heart phenotypes. In Ciona, ETS affinity-optimizing SNVs lead to ectopic expression and phenotypic changes including two beating hearts. In human iPSC-CMs, an affinity-optimizing SNV associated with QRS duration occurs within an SCN5A enhancer and leads to increased enhancer activity. Our mechanistic approach provides a much-needed systematic framework that works across different enhancers, cell types and species to pinpoint causal enhancer variants contributing to enhanceropathies, phenotypic diversity and evolutionary changes.In BriefThe prevalent use of low-affinity ETS sites within developmental heart enhancers creates vulnerability within genomes whereby single nucleotide changes can dramatically increase binding affinity, causing gain-of-function enhancer activity that impacts heart development.HighlightsETS affinity-optimizing SNVs can lead to migration defects and a multi-chambered heart.An ETS affinity-optimizing human SNV within an SCN5A enhancer increases expression and is associated with QRS duration.Searching for ETS affinity-optimizing variants is a systematic and generalizable approach to pinpoint causal enhancer variants.

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Overexpression of SCN5A in mouse heart mimics human syndrome of enhanced atrioventricular nodal conduction

Cited by 11 publications

References 22 publications

In vivo Dominant-Negative Effect of an SCN5A Brugada Syndrome Variant

In vivo Dominant-Negative Effect of an SCN5A Brugada Syndrome Variant

Cardiac-specific inactivation of Prdm16 effects cardiac conduction abnormalities and cardiomyopathy-associated phenotypes

Affinity-optimizing variants within cardiac enhancers disrupt heart development and contribute to cardiac traits

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