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Jennifer A Kearney - One of the best experts on this subject based on the ideXlab platform.

  • unexpected efficacy of a novel sodium channel modulator in dravet syndrome
    Scientific Reports, 2017
    Co-Authors: Lyndsey L Anderson, Christopher H Thompson, Nicole A Hawkins, Jennifer A Kearney, Alfred L George
    Abstract:

    Dravet syndrome, an epileptic encephalopathy affecting children, largely results from heterozygous loss-of-function mutations in the brain voltage-gated sodium channel gene SCN1A. Heterozygous Scn1a knockout (Scn1a +/-) mice recapitulate the severe epilepsy phenotype of Dravet syndrome and are an accepted animal model. Because clinical observations suggest conventional sodium channel blocking antiepileptic drugs may worsen the disease, we predicted the phenotype of Scn1a +/- mice would be exacerbated by GS967, a potent, unconventional sodium channel blocker. Unexpectedly, GS967 significantly improved survival of Scn1a +/- mice and suppressed spontaneous seizures. By contrast, lamotrigine exacerbated the seizure phenotype. Electrophysiological recordings of acutely dissociated neurons revealed that chronic GS967-treatment had no impact on evoked action potential firing frequency of interneurons, but did suppress aberrant spontaneous firing of pyramidal neurons and was associated with significantly lower sodium current density. Lamotrigine had no effects on neuronal excitability of either neuron subtype. Additionally, chronically GS967-treated Scn1a +/- mice exhibited normalized pyramidal neuron sodium current density and reduced hippocampal NaV1.6 protein levels, whereas lamotrigine treatment had no effect on either pyramidal neuron sodium current or hippocampal NaV1.6 levels. Our findings demonstrate unexpected efficacy of a novel sodium channel blocker in Dravet syndrome and suggest a potential mechanism involving a secondary change in NaV1.6.

  • screening of conventional anticonvulsants in a genetic mouse model of epilepsy
    Annals of clinical and translational neurology, 2017
    Co-Authors: Nicole A Hawkins, Alfred L George, Lyndsey L Anderson, Tracy S Gertler, Linda Laux, Jennifer A Kearney
    Abstract:

    Objective Epilepsy is a common neurological disorder that affects 1% of the population. Approximately, 30% of individuals with epilepsy are refractory to treatment, highlighting the need for novel therapies. Conventional anticonvulsant screening relies predominantly on induced seizure models. However, these models may not be etiologically relevant for genetic epilepsies. Mutations in SCN1A are a common cause of Dravet Syndrome, a severe epileptic encephalopathy. Dravet syndrome typically begins in infancy with seizures provoked by fever and then progresses to include afebrile pleomorphic seizure types. Affected children respond poorly to available anticonvulsants. Scn1a+/− heterozygous knockout mice recapitulate features of Dravet syndrome and provide a potential screening platform to investigate novel therapeutics. In this study, we conducted a screening of conventional anticonvulsants in Scn1a+/− mice to establish assays that most closely correlate with human response data. Methods On the basis of clinical response data from a large, single center, retrospective survey of Dravet syndrome case records, we selected nine drugs for screening in Scn1a+/− mice to determine which phenotypic measures correlate best with human therapeutic response. We evaluated several screening paradigms and incorporated pharmacokinetic monitoring to establish drug exposure levels. Results Scn1a+/− mice exhibited responses to anticonvulsant treatment similar to those observed clinically. Sodium channel blockers were not effective or exacerbated seizures in Scn1a+/− mice. Overall, clobazam was the most effective anticonvulsant in Scn1a+/− mice, consistent with its effect in Dravet syndrome. Interpretation Genetic models of spontaneous epilepsy provide alternative screening platforms and may augment the AED development process. In this study, we established an effective screening platform that pharmacologically validated Scn1a+/− mice for preclinical screening of potential Dravet syndrome therapeutics.

  • fine mapping of a dravet syndrome modifier locus on mouse chromosome 5 and candidate gene analysis by rna seq
    PLOS Genetics, 2016
    Co-Authors: Nicole A Hawkins, Jennifer A Kearney, Lyndsey L Anderson, Alison R Miller, Nicole J Zachwieja
    Abstract:

    A substantial number of mutations have been identified in voltage-gated sodium channel genes that result in various forms of human epilepsy. SCN1A mutations result in a spectrum of severity ranging from mild febrile seizures to Dravet syndrome, an infant-onset epileptic encephalopathy. Dravet syndrome patients experience multiple seizures types that are often refractory to treatment, developmental delays, and elevated risk for SUDEP. The same sodium channel mutation can produce epilepsy phenotypes of varying clinical severity. This suggests that other factors, including genetic, modify the primary mutation and change disease severity. Mouse models provide a useful tool in studying the genetic basis of epilepsy. The mouse strain background can alter phenotype severity, supporting a contribution of genetic modifiers in epilepsy. The Scn1a+/- mouse model has a strain-dependent epilepsy phenotype. Scn1a+/- mice on the 129S6/SvEvTac (129) strain have a normal phenotype and lifespan, while [129xC57BL/6J]F1-Scn1a+/- mice experience spontaneous seizures, hyperthermia-induced seizures and high rates of premature death. We hypothesize the phenotypic differences are due to strain-specific genetic modifiers that influence expressivity of the Scn1a+/- phenotype. Low resolution mapping of Scn1a+/- identified several Dravet syndrome modifier (Dsm) loci responsible for the strain-dependent difference in survival. One locus of interest, Dsm1 located on chromosome 5, was fine mapped to a 9 Mb region using interval specific congenics. RNA-Seq was then utilized to identify candidate modifier genes within this narrowed region. Three genes with significant total gene expression differences between 129S6/SvEvTac and [129xC57BL/6J]F1 were identified, including the GABAA receptor subunit, Gabra2. Further analysis of Gabra2 demonstrated allele-specific expression. Pharmological manipulation by clobazam, a common anticonvulsant with preferential affinity for the GABRA2 receptor, revealed dose-dependent protection against hyperthermia-induced seizures in Scn1a+/- mice. These findings support Gabra2 as a genetic modifier of the Scn1a+/- mouse model of Dravet syndrome.

  • fine mapping of a dravet syndrome modifier locus on mouse chromosome 5 and candidate gene analysis by rna seq
    PLOS Genetics, 2016
    Co-Authors: Nicole A Hawkins, Jennifer A Kearney, Lyndsey L Anderson, Alison R Miller, Nicole J Zachwieja
    Abstract:

    A substantial number of mutations have been identified in voltage-gated sodium channel genes that result in various forms of human epilepsy. SCN1A mutations result in a spectrum of severity ranging from mild febrile seizures to Dravet syndrome, an infant-onset epileptic encephalopathy. Dravet syndrome patients experience multiple seizures types that are often refractory to treatment, developmental delays, and elevated risk for SUDEP. The same sodium channel mutation can produce epilepsy phenotypes of varying clinical severity. This suggests that other factors, including genetic, modify the primary mutation and change disease severity. Mouse models provide a useful tool in studying the genetic basis of epilepsy. The mouse strain background can alter phenotype severity, supporting a contribution of genetic modifiers in epilepsy. The Scn1a+/- mouse model has a strain-dependent epilepsy phenotype. Scn1a+/- mice on the 129S6/SvEvTac (129) strain have a normal phenotype and lifespan, while [129xC57BL/6J]F1-Scn1a+/- mice experience spontaneous seizures, hyperthermia-induced seizures and high rates of premature death. We hypothesize the phenotypic differences are due to strain-specific genetic modifiers that influence expressivity of the Scn1a+/- phenotype. Low resolution mapping of Scn1a+/- identified several Dravet syndrome modifier (Dsm) loci responsible for the strain-dependent difference in survival. One locus of interest, Dsm1 located on chromosome 5, was fine mapped to a 9 Mb region using interval specific congenics. RNA-Seq was then utilized to identify candidate modifier genes within this narrowed region. Three genes with significant total gene expression differences between 129S6/SvEvTac and [129xC57BL/6J]F1 were identified, including the GABAA receptor subunit, Gabra2. Further analysis of Gabra2 demonstrated allele-specific expression. Pharmological manipulation by clobazam, a common anticonvulsant with preferential affinity for the GABRA2 receptor, revealed dose-dependent protection against hyperthermia-induced seizures in Scn1a+/- mice. These findings support Gabra2 as a genetic modifier of the Scn1a+/- mouse model of Dravet syndrome.

  • mapping genetic modifiers of survival in a mouse model of dravet syndrome
    Genes Brain and Behavior, 2014
    Co-Authors: Alison R Miller, Nicole A Hawkins, Clint E Mccollom, Jennifer A Kearney
    Abstract:

    Epilepsy is a common neurological disorder affecting approximately 1% of the population. Mutations in voltage-gated sodium channels are responsible for several monogenic epilepsy syndromes. More than 800 mutations in the voltage-gated sodium channel SCN1A have been reported in patients with generalized epilepsy with febrile seizures plus and Dravet syndrome. Heterozygous loss-of-function mutations in SCN1A result in Dravet syndrome, a severe infant-onset epileptic encephalopathy characterized by intractable seizures, developmental delays and increased mortality. A common feature of monogenic epilepsies is variable expressivity among individuals with the same mutation, suggesting that genetic modifiers may influence clinical severity. Mice with heterozygous deletion of Scn1a (Scn1a(+/-) ) model a number of Dravet syndrome features, including spontaneous seizures and premature lethality. Phenotype severity in Scn1a(+/-) mice is strongly dependent on strain background. On the 129S6/SvEvTac strain Scn1a(+/-) mice exhibit no overt phenotype, whereas on the (C57BL/6J × 129S6/SvEvTac)F1 strain Scn1a(+/-) mice exhibit spontaneous seizures and early lethality. To systematically identify loci that influence premature lethality in Scn1a(+/-) mice, we performed genome scans on reciprocal backcrosses. Quantitative trait locus mapping revealed modifier loci on mouse chromosomes 5, 7, 8 and 11. RNA-seq analysis of strain-dependent gene expression, regulation and coding sequence variation provided a list of potential functional candidate genes at each locus. Identification of modifier genes that influence survival in Scn1a(+/-) mice will improve our understanding of the pathophysiology of Dravet syndrome and may suggest novel therapeutic strategies for improved treatment of human patients.

Dan M Roden - One of the best experts on this subject based on the ideXlab platform.

  • abstract 17782 both common and rare SCN10A variants associated with brugada syndrome displayed an increase in late nav1 8 sodium currents in nd 7 23 cells
    Circulation, 2014
    Co-Authors: Eleonora Saviogalimberti, Dan M Roden, Tao Yang, Yalda Jamshidi, Elijah R Behr, Kaylen Kor, Evmorfia Petropoulou, Pascale Guicheney, Jacob Tfelthansen, Arthur A M Wilde
    Abstract:

    Introduction: Brugada syndrome (BrS) is an oligogenic disease, often linked to mutations in SCN5A encoding the canonical cardiac sodium channel. Prolongation of QRS interval implicates slowed cardiac conduction as an important element of the BrS arrhythmia phenotype. Recent genome-wide association studies have implicated common variation in SCN10A as a potential modulator of cardiac conduction. SCN10A encodes the tetrodotoxin-resistant voltage-gated sodium channel isoform Nav1.8 primarily found in dorsal root ganglia and at lower levels in the heart. A recent candidate gene sequencing study identified 5 non-synonymous SCN10A rare variants in 4/156 white SCN5A mutation-negative patients with BrS and one protective non-synonymous common variant V1073A [(T>C): T allele BrS vs. control: 65.1% vs. 40.1%, P = 3.54x10-19]. Hypothesis: Here we tested the hypothesis that the common variant (V1073A) and 2 of the rare variants identified (A200V, I671V) generate aberrant Nav1.8 function and this may contribute to BrS...

  • abstract 18012 modeling of a rare SCN10A variant a1886v linked with early onset atrial fibrillation shortens atrial action potential duration
    Circulation, 2014
    Co-Authors: Robert L Abraham, Dan M Roden, Tao Yang, Eleonora Saviogalimberti, Dawood Darbar
    Abstract:

    Introduction: SCN10A encodes the tetrodotoxin-resistant sodium channel isoform Nav1.8, which is variably expressed in neuronal tissue and heart and has been associated with atrial fibrillation (AF)...

  • common SCN10A variants modulate pr interval and heart rate response during atrial fibrillation
    Europace, 2014
    Co-Authors: Jessica T Delaney, Dan M Roden, Raafia Muhammad, Yaping Shi, Jonathan S Schildcrout, Marcia Blair, Laura Short, Dawood Darbar
    Abstract:

    Aims SCN10A encodes the sodium channel Nav1.8 implicated by genome-wide association studies as a modulator of atrioventricular conduction (PR interval). In a cohort of patients with atrial fibrillation (AF), we examined whether there was an association between common variants in SCN10A and both the PR interval during normal sinus rhythm and the heart rate response during AF. Methods and results Patients prospectively enrolled in the Vanderbilt AF registry with electrocardiograms in normal sinus rhythm and/or AF within 1 year of enrollment were genotyped for two common SCN10A variants rs6795970 and rs12632942. Both variants were associated with the PR interval duration in a gene-dose effect on unadjusted analysis; after adjustment for the covariates age, gender, body mass index, hypertension, congestive heart failure, and medication usage, the association remained for rs6795970 only ( P = 0.012, partial R 2 = 0.0139). On unadjusted analysis, heart rate response during AF was associated with rs6795970 ( P = 0.035, partial R 2 = 0.015), but not with rs12632942 ( P = 0.89), and neither association was significant after adjustment for covariates. Conclusion The common variant rs6795970 in SCN10A is associated with the PR interval duration among healthy patients and those with AF. In addition, this single nucleotide polymorphism trended towards an association with heart rate response during AF indicating the importance of this common SCN10A polymorphism as a marker of atrioventricular conduction.

  • blocking SCN10A channels in heart reduces late sodium current and is antiarrhythmic
    Circulation Research, 2012
    Co-Authors: Tao Yang, Thomas C Atack, Dina Myers Stroud, Lynn Hall, Wei Zhang, Dan M Roden
    Abstract:

    Rationale: While the sodium channel locus SCN10A has been implicated by genome-wide association studies as a modulator of cardiac electrophysiology, the role of its gene product Nav1.8 as a modulator of cardiac ion currents is unknown. Objective: We determined the electrophysiological and pharmacological properties of Nav1.8 in heterologous cell systems and assessed the antiarrhythmic effect of Nav1.8 block on isolated mouse and rabbit ventricular cardiomyocytes. Methods and Results: We first demonstrated that SCN10A transcripts are identified in mouse heart and that the blocker A-803467 is highly specific for Nav1.8 current over that of Nav1.5, the canonical cardiac sodium channel encoded by SCN5A. We then showed that low concentrations of A-803467 selectively block “late” sodium current and shorten action potentials in mouse and rabbit cardiomyocytes. Exaggerated late sodium current is known to mediate arrhythmogenic early afterdepolarizations in heart, and these were similarly suppressed by low concentrations of A-803467. Conclusions: SCN10A expression contributes to late sodium current in heart, and represents a new target for antiarrhythmic intervention.

  • identification of genomic predictors of atrioventricular conduction using electronic medical records as a tool for genome science
    Circulation, 2010
    Co-Authors: Joshua C Denny, Jonathan S Schildcrout, Marylyn D Ritchie, Dana C Crawford, Andrea H Ramirez, Jill M Pulley, Melissa A Basford, Daniel R Masys, Jonathan L Haines, Dan M Roden
    Abstract:

    Background—Recent genome-wide association studies in which selected community populations are used have identified genomic signals in SCN10A influencing PR duration. The extent to which this can be demonstrated in cohorts derived from electronic medical records is unknown. Methods and Results—We performed a genome-wide association study on 2334 European American patients with normal ECGs without evidence of prior heart disease from the Vanderbilt DNA databank, BioVU, which accrues subjects from routine patient care. Subjects were identified by combinations of natural language processing, laboratory queries, and billing code queries of deidentified medical record data. Subjects were 58% female, of mean (±SD) age 54±15 years, and had mean PR intervals of 158±18 ms. Genotyping was performed with the use of the Illumina Human660W-Quad platform. Our results identify 4 single nucleotide polymorphisms (rs6800541, rs6795970, rs6798015, rs7430477) linked to SCN10A associated with PR interval (P=5.73×10−7 to 1.78×1...

Marieke W Veldkamp - One of the best experts on this subject based on the ideXlab platform.

  • absence of functional nav1 8 channels in non diseased atrial and ventricular cardiomyocytes
    Cardiovascular Drugs and Therapy, 2019
    Co-Authors: Simona Casini, Marieke W Veldkamp, Gerard A Marchal, Makiri Kawasaki, Fransisca A Nariswari, Vincent Portero, Nicoline W E Van Den Berg, Kaomei Guan, Antoine H G Driessen, Isabella Mengarelli
    Abstract:

    Several studies have indicated a potential role for SCN10A/NaV1.8 in modulating cardiac electrophysiology and arrhythmia susceptibility. However, by which mechanism SCN10A/NaV1.8 impacts on cardiac electrical function is still a matter of debate. To address this, we here investigated the functional relevance of NaV1.8 in atrial and ventricular cardiomyocytes (CMs), focusing on the contribution of NaV1.8 to the peak and late sodium current (INa) under normal conditions in different species. The effects of the NaV1.8 blocker A-803467 were investigated through patch-clamp analysis in freshly isolated rabbit left ventricular CMs, human left atrial CMs and human-induced pluripotent stem cell-derived CMs (hiPSC-CMs). A-803467 treatment caused a slight shortening of the action potential duration (APD) in rabbit CMs and hiPSC-CMs, while it had no effect on APD in human atrial cells. Resting membrane potential, action potential (AP) amplitude, and AP upstroke velocity were unaffected by A-803467 application. Similarly, INa density was unchanged after exposure to A-803467 and NaV1.8-based late INa was undetectable in all cell types analysed. Finally, low to absent expression levels of SCN10A were observed in human atrial tissue, rabbit ventricular tissue and hiPSC-CMs. We here demonstrate the absence of functional NaV1.8 channels in non-diseased atrial and ventricular CMs. Hence, the association of SCN10A variants with cardiac electrophysiology observed in, e.g. genome wide association studies, is likely the result of indirect effects on SCN5A expression and/or NaV1.8 activity in cell types other than CMs.

  • functional nav1 8 channels in intracardiac neuronsnovelty and significance the link between SCN10A and cardiac electrophysiology
    Circulation Research, 2012
    Co-Authors: Arie O. Verkerk, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Berend De Jonge, Marieke W Veldkamp
    Abstract:

    Rationale: The SCN10A gene encodes the neuronal sodium channel isoform Na V 1.8. Several recent genome-wide association studies have linked SCN10A to PR interval and QRS duration, strongly suggesting an as-yet unknown role for Na V 1.8 in cardiac electrophysiology. Objective: To demonstrate the functional presence of SCN10A /Nav1.8 in intracardiac neurons of the mouse heart. Methods and Results: Immunohistochemistry on mouse tissue sections showed intense Na V 1.8 labeling in dorsal root ganglia and intracardiac ganglia and only modest Na V 1.8 expression within the myocardium. Immunocytochemistry further revealed substantial Na V 1.8 staining in isolated neurons from murine intracardiac ganglia but no Na V 1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the Na V 1.8 blocker A-803467 (0.5–2 μmol/L) had no effect on either mean sodium current (I Na ) density or I Na gating kinetics in isolated myocytes but significantly reduced I Na density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage dependence of inactivation toward more negative voltages, as expected for blockade of Na V 1.8-based I Na . In line with these findings, A-803467 did not affect cardiomyocyte action potential upstroke velocity but markedly reduced action potential firing frequency in intracardiac neurons, confirming a functional role for Na V 1.8 in cardiac neural activity. Conclusions: Our findings demonstrate the functional presence of SCN10A /Na V 1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electric activity.

  • functional nav1 8 channels in intracardiac neurons the link between SCN10A and cardiac electrophysiology
    Circulation Research, 2012
    Co-Authors: Arie O. Verkerk, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Berend De Jonge, Marieke W Veldkamp
    Abstract:

    Rationale: The SCN10A gene encodes the neuronal sodium channel isoform Na V 1.8. Several recent genome-wide association studies have linked SCN10A to PR interval and QRS duration, strongly suggesting an as-yet unknown role for Na V 1.8 in cardiac electrophysiology. Objective: To demonstrate the functional presence of SCN10A /Nav1.8 in intracardiac neurons of the mouse heart. Methods and Results: Immunohistochemistry on mouse tissue sections showed intense Na V 1.8 labeling in dorsal root ganglia and intracardiac ganglia and only modest Na V 1.8 expression within the myocardium. Immunocytochemistry further revealed substantial Na V 1.8 staining in isolated neurons from murine intracardiac ganglia but no Na V 1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the Na V 1.8 blocker A-803467 (0.5–2 μmol/L) had no effect on either mean sodium current (I Na ) density or I Na gating kinetics in isolated myocytes but significantly reduced I Na density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage dependence of inactivation toward more negative voltages, as expected for blockade of Na V 1.8-based I Na . In line with these findings, A-803467 did not affect cardiomyocyte action potential upstroke velocity but markedly reduced action potential firing frequency in intracardiac neurons, confirming a functional role for Na V 1.8 in cardiac neural activity. Conclusions: Our findings demonstrate the functional presence of SCN10A /Na V 1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electric activity.

  • functional nav1 8 channels in intracardiac neurons the link between SCN10A and cardiac electrophysiology
    Circulation Research, 2012
    Co-Authors: Arie O. Verkerk, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Berend De Jonge, Marieke W Veldkamp
    Abstract:

    Rationale: The SCN10A gene encodes the neuronal sodium channel isoform NaV1.8. Several recent genome-wide association studies have linked SCN10A to PR-interval and QRS-duration, strongly suggesting an as yet unknown role for NaV1.8 in cardiac electrophysiology. Objective: To demonstrate the functional presence of SCN10A/Nav1.8 in intracardiac neurons of the mouse heart. Methods and Results: Immunohistochemistry on mouse tissue sections showed intense NaV1.8 labeling in dorsal root ganglia and intracardiac ganglia, and only modest NaV1.8 expression within the myocardium. Immunocytochemistry further revealed substantial NaV1.8 staining in isolated neurons from murine intracardiac ganglia, but no NaV1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the NaV1.8 blocker A-803467 (0.5-2 µM) had no effect on either mean sodium current (INa) density or INa gating kinetics in isolated myocytes, but significantly reduced INa density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage-dependence of inactivation towards more negative voltages, as expected for blockade of NaV1.8-based INa. In line with these findings, A-803467 did not affect cardiomyocyte action potential (AP) upstroke velocity, but markedly reduced AP firing frequency in intracardiac neurons, confirming a functional role for NaV1.8 in cardiac neural activity. Conclusions: Our findings demonstrate the functional presence of SCN10A/NaV1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electrical activity.

  • the selective nav1 8 sodium channel blocker a 803467 affects electrical activity in intracardiac neurons but not in cardiomyocytes
    Biophysical Journal, 2011
    Co-Authors: Marieke W Veldkamp, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Antoni C G Van Ginneken, Arie O. Verkerk
    Abstract:

    Background. Recently we observed differential myocardial expression of the brain-type sodium channel isoform SCN10A between two inbred mouse strains, both harboring the Scn5a-1798insD+/- mutation and displaying different severity of conduction disease. The functional role of SCN10A in the heart is as yet unknown, and we therefore investigated expression and channel activity of NaV1.8 (encoded by SCN10A) in intracardiac neurons and myocardium of the murine heart.Methods. Immunocytochemistry was performed using anti-NaV1.8 antibody on mouse embryos and adult murine cardiac tissue sections. The effect of the NaV1.8 blocker A-803467 (500 nM) on action potentials (AP's) and sodium current (INa) properties was assessed in isolated intracardiac neurons and ventricular myocytes.Results. In embryonic and adult heart tissue sections, NaV1.8 staining was observed at the epicardial surface, and within the myocardium in between cardiomyocytes. The NaV1.8 blocker A-803467 had no effect on either mean INa density or INa kinetic properties in isolated myocytes, but clearly reduced INa density in intracardiac neurons (−344±51 pA/pF versus control −448±61; mean±SEM, n=11). In addition, the slow component of the current decay (τslow) at −20 mV was accelerated in the presence of A-803467 (2.8±0.3 ms versus control 3.4±0.4 ms; mean±SEM, n=5) and V1/2 of voltage-dependent inactivation was shifted by −9.6 mV (−73.6±2.0 mV versus control −64.0±1.6 mV; mean±SEM, n=5). This is consistent with a reduction in slowly inactivating brain-type sodium current with depolarized voltage-dependent inactivation. In AP measurements A-803467 did not affect cardiomyocyte upstroke velocity, but reduced AP firing frequency in intracardiac neurons by 50%.Conclusion. The sodium channel NaV1.8 is expressed in murine heart, and is functionally present in intracardiac neurons, but absent in cardiomyocytes. Thus, NaV1.8 may influence myocardial electrophysiological properties through its contribution to cardiac neuronal activity.

Arie O. Verkerk - One of the best experts on this subject based on the ideXlab platform.

  • common variants at scn5a SCN10A and hey2 are associated with brugada syndrome a rare disease with high risk of sudden cardiac death
    Nature Genetics, 2013
    Co-Authors: Connie R Bezzina, Carol Ann Remme, Arie O. Verkerk, Julien Barc, Yuka Mizusawa, Jeanbaptiste Gourraud, Floriane Simonet, Peter J Schwartz
    Abstract:

    Brugada syndrome is a rare cardiac arrhythmia disorder, causally related to SCN5A mutations in around 20% of cases. Through a genome-wide association study of 312 individuals with Brugada syndrome and 1,115 controls, we detected 2 significant association signals at the SCN10A locus (rs10428132) and near the HEY2 gene (rs9388451). Independent replication confirmed both signals (meta-analyses: rs10428132, P = 1.0 × 10(-68); rs9388451, P = 5.1 × 10(-17)) and identified one additional signal in SCN5A (at 3p21; rs11708996, P = 1.0 × 10(-14)). The cumulative effect of the three loci on disease susceptibility was unexpectedly large (Ptrend = 6.1 × 10(-81)). The association signals at SCN5A-SCN10A demonstrate that genetic polymorphisms modulating cardiac conduction can also influence susceptibility to cardiac arrhythmia. The implication of association with HEY2, supported by new evidence that Hey2 regulates cardiac electrical activity, shows that Brugada syndrome may originate from altered transcriptional programming during cardiac development. Altogether, our findings indicate that common genetic variation can have a strong impact on the predisposition to rare diseases.

  • functional nav1 8 channels in intracardiac neuronsnovelty and significance the link between SCN10A and cardiac electrophysiology
    Circulation Research, 2012
    Co-Authors: Arie O. Verkerk, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Berend De Jonge, Marieke W Veldkamp
    Abstract:

    Rationale: The SCN10A gene encodes the neuronal sodium channel isoform Na V 1.8. Several recent genome-wide association studies have linked SCN10A to PR interval and QRS duration, strongly suggesting an as-yet unknown role for Na V 1.8 in cardiac electrophysiology. Objective: To demonstrate the functional presence of SCN10A /Nav1.8 in intracardiac neurons of the mouse heart. Methods and Results: Immunohistochemistry on mouse tissue sections showed intense Na V 1.8 labeling in dorsal root ganglia and intracardiac ganglia and only modest Na V 1.8 expression within the myocardium. Immunocytochemistry further revealed substantial Na V 1.8 staining in isolated neurons from murine intracardiac ganglia but no Na V 1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the Na V 1.8 blocker A-803467 (0.5–2 μmol/L) had no effect on either mean sodium current (I Na ) density or I Na gating kinetics in isolated myocytes but significantly reduced I Na density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage dependence of inactivation toward more negative voltages, as expected for blockade of Na V 1.8-based I Na . In line with these findings, A-803467 did not affect cardiomyocyte action potential upstroke velocity but markedly reduced action potential firing frequency in intracardiac neurons, confirming a functional role for Na V 1.8 in cardiac neural activity. Conclusions: Our findings demonstrate the functional presence of SCN10A /Na V 1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electric activity.

  • functional nav1 8 channels in intracardiac neurons the link between SCN10A and cardiac electrophysiology
    Circulation Research, 2012
    Co-Authors: Arie O. Verkerk, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Berend De Jonge, Marieke W Veldkamp
    Abstract:

    Rationale: The SCN10A gene encodes the neuronal sodium channel isoform Na V 1.8. Several recent genome-wide association studies have linked SCN10A to PR interval and QRS duration, strongly suggesting an as-yet unknown role for Na V 1.8 in cardiac electrophysiology. Objective: To demonstrate the functional presence of SCN10A /Nav1.8 in intracardiac neurons of the mouse heart. Methods and Results: Immunohistochemistry on mouse tissue sections showed intense Na V 1.8 labeling in dorsal root ganglia and intracardiac ganglia and only modest Na V 1.8 expression within the myocardium. Immunocytochemistry further revealed substantial Na V 1.8 staining in isolated neurons from murine intracardiac ganglia but no Na V 1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the Na V 1.8 blocker A-803467 (0.5–2 μmol/L) had no effect on either mean sodium current (I Na ) density or I Na gating kinetics in isolated myocytes but significantly reduced I Na density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage dependence of inactivation toward more negative voltages, as expected for blockade of Na V 1.8-based I Na . In line with these findings, A-803467 did not affect cardiomyocyte action potential upstroke velocity but markedly reduced action potential firing frequency in intracardiac neurons, confirming a functional role for Na V 1.8 in cardiac neural activity. Conclusions: Our findings demonstrate the functional presence of SCN10A /Na V 1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electric activity.

  • functional nav1 8 channels in intracardiac neurons the link between SCN10A and cardiac electrophysiology
    Circulation Research, 2012
    Co-Authors: Arie O. Verkerk, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Berend De Jonge, Marieke W Veldkamp
    Abstract:

    Rationale: The SCN10A gene encodes the neuronal sodium channel isoform NaV1.8. Several recent genome-wide association studies have linked SCN10A to PR-interval and QRS-duration, strongly suggesting an as yet unknown role for NaV1.8 in cardiac electrophysiology. Objective: To demonstrate the functional presence of SCN10A/Nav1.8 in intracardiac neurons of the mouse heart. Methods and Results: Immunohistochemistry on mouse tissue sections showed intense NaV1.8 labeling in dorsal root ganglia and intracardiac ganglia, and only modest NaV1.8 expression within the myocardium. Immunocytochemistry further revealed substantial NaV1.8 staining in isolated neurons from murine intracardiac ganglia, but no NaV1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the NaV1.8 blocker A-803467 (0.5-2 µM) had no effect on either mean sodium current (INa) density or INa gating kinetics in isolated myocytes, but significantly reduced INa density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage-dependence of inactivation towards more negative voltages, as expected for blockade of NaV1.8-based INa. In line with these findings, A-803467 did not affect cardiomyocyte action potential (AP) upstroke velocity, but markedly reduced AP firing frequency in intracardiac neurons, confirming a functional role for NaV1.8 in cardiac neural activity. Conclusions: Our findings demonstrate the functional presence of SCN10A/NaV1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electrical activity.

  • the selective nav1 8 sodium channel blocker a 803467 affects electrical activity in intracardiac neurons but not in cardiomyocytes
    Biophysical Journal, 2011
    Co-Authors: Marieke W Veldkamp, Cees A Schumacher, Brendon P Scicluna, Rianne Wolswinkel, Carol Ann Remme, Connie R Bezzina, Antoni C G Van Ginneken, Arie O. Verkerk
    Abstract:

    Background. Recently we observed differential myocardial expression of the brain-type sodium channel isoform SCN10A between two inbred mouse strains, both harboring the Scn5a-1798insD+/- mutation and displaying different severity of conduction disease. The functional role of SCN10A in the heart is as yet unknown, and we therefore investigated expression and channel activity of NaV1.8 (encoded by SCN10A) in intracardiac neurons and myocardium of the murine heart.Methods. Immunocytochemistry was performed using anti-NaV1.8 antibody on mouse embryos and adult murine cardiac tissue sections. The effect of the NaV1.8 blocker A-803467 (500 nM) on action potentials (AP's) and sodium current (INa) properties was assessed in isolated intracardiac neurons and ventricular myocytes.Results. In embryonic and adult heart tissue sections, NaV1.8 staining was observed at the epicardial surface, and within the myocardium in between cardiomyocytes. The NaV1.8 blocker A-803467 had no effect on either mean INa density or INa kinetic properties in isolated myocytes, but clearly reduced INa density in intracardiac neurons (−344±51 pA/pF versus control −448±61; mean±SEM, n=11). In addition, the slow component of the current decay (τslow) at −20 mV was accelerated in the presence of A-803467 (2.8±0.3 ms versus control 3.4±0.4 ms; mean±SEM, n=5) and V1/2 of voltage-dependent inactivation was shifted by −9.6 mV (−73.6±2.0 mV versus control −64.0±1.6 mV; mean±SEM, n=5). This is consistent with a reduction in slowly inactivating brain-type sodium current with depolarized voltage-dependent inactivation. In AP measurements A-803467 did not affect cardiomyocyte upstroke velocity, but reduced AP firing frequency in intracardiac neurons by 50%.Conclusion. The sodium channel NaV1.8 is expressed in murine heart, and is functionally present in intracardiac neurons, but absent in cardiomyocytes. Thus, NaV1.8 may influence myocardial electrophysiological properties through its contribution to cardiac neuronal activity.

Eleonora Saviogalimberti - One of the best experts on this subject based on the ideXlab platform.

  • role of common and rare variants in SCN10A results from the brugada syndrome qrs locus gene discovery collaborative study
    Cardiovascular Research, 2015
    Co-Authors: Elijah R Behr, Eleonora Saviogalimberti, Evmorfia Petropoulou, Julien Barc, Anders G Holst, Bram P Prins, Javad Jabbari
    Abstract:

    Aims Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac conduction. We aimed to identify genetic variation in BrS cases at loci associated with QRS duration. Methods and results A multi-centre study sequenced seven candidate genes ( SCN10A , HAND1 , PLN , CASQ2 , TKT , TBX3 , and TBX5 ) in 156 Caucasian SCN5A mutation-negative BrS patients (80% male; mean age 48) with symptoms (64%) and/or a family history of sudden death (47%) or BrS (18%). Forty-nine variants were identified: 18 were rare (MAF <1%) and non-synonymous; and 11/18 (61.1%), mostly in SCN10A , were predicted as pathogenic using multiple bioinformatics tools. Allele frequencies were compared with the Exome Sequencing and UK10K Projects. SKAT methods tested rare variation in SCN10A finding no statistically significant difference between cases and controls. Co-segregation analysis was possible for four of seven probands carrying a novel pathogenic variant. Only one pedigree (I671V/G1299A in SCN10A ) showed co-segregation. The SCN10A SNP V1073 was, however, associated strongly with BrS [66.9 vs. 40.1% (UK10K) OR (95% CI) = 3.02 (2.35–3.87), P = 8.07 × 10–19]. Voltage-clamp experiments for NaV1.8 were performed for SCN10A common variants V1073, A1073, and rare variants of interest: A200V and I671V. V1073, A200V and I671V, demonstrated significant reductions in peak I Na compared with ancestral allele A1073 (rs6795970). Conclusion Rare variants in the screened QRS-associated genes (including SCN10A ) are not responsible for a significant proportion of SCN5A mutation negative BrS. The common SNP SCN10A V1073 was strongly associated with BrS and demonstrated loss of NaV1.8 function, as did rare variants in isolated patients.

  • abstract 17782 both common and rare SCN10A variants associated with brugada syndrome displayed an increase in late nav1 8 sodium currents in nd 7 23 cells
    Circulation, 2014
    Co-Authors: Eleonora Saviogalimberti, Dan M Roden, Tao Yang, Yalda Jamshidi, Elijah R Behr, Kaylen Kor, Evmorfia Petropoulou, Pascale Guicheney, Jacob Tfelthansen, Arthur A M Wilde
    Abstract:

    Introduction: Brugada syndrome (BrS) is an oligogenic disease, often linked to mutations in SCN5A encoding the canonical cardiac sodium channel. Prolongation of QRS interval implicates slowed cardiac conduction as an important element of the BrS arrhythmia phenotype. Recent genome-wide association studies have implicated common variation in SCN10A as a potential modulator of cardiac conduction. SCN10A encodes the tetrodotoxin-resistant voltage-gated sodium channel isoform Nav1.8 primarily found in dorsal root ganglia and at lower levels in the heart. A recent candidate gene sequencing study identified 5 non-synonymous SCN10A rare variants in 4/156 white SCN5A mutation-negative patients with BrS and one protective non-synonymous common variant V1073A [(T>C): T allele BrS vs. control: 65.1% vs. 40.1%, P = 3.54x10-19]. Hypothesis: Here we tested the hypothesis that the common variant (V1073A) and 2 of the rare variants identified (A200V, I671V) generate aberrant Nav1.8 function and this may contribute to BrS...

  • abstract 18012 modeling of a rare SCN10A variant a1886v linked with early onset atrial fibrillation shortens atrial action potential duration
    Circulation, 2014
    Co-Authors: Robert L Abraham, Dan M Roden, Tao Yang, Eleonora Saviogalimberti, Dawood Darbar
    Abstract:

    Introduction: SCN10A encodes the tetrodotoxin-resistant sodium channel isoform Nav1.8, which is variably expressed in neuronal tissue and heart and has been associated with atrial fibrillation (AF)...

  • SCN10A nav1 8 modulation of peak and late sodium currents in patients with early onset atrial fibrillation
    Cardiovascular Research, 2014
    Co-Authors: Eleonora Saviogalimberti, Thomas C Atack, Carlos G Vanoye, Raafia Muhammad, Marcia Blair, Laura Short, Kaylen Kor, Peter Weeke, Sami Ansari, Morten S Olesen
    Abstract:

    Aims To test the hypothesis that vulnerability to atrial fibrillation (AF) is associated with rare coding sequence variation in the SCN10A gene, which encodes the voltage-gated sodium channel isoform NaV1.8 found primarily in peripheral nerves and to identify potentially disease-related mechanisms in high-priority rare variants using in-vitro electrophysiology. Methods and results We re-sequenced SCN10A in 274 patients with early onset AF from the Vanderbilt AF Registry to identify rare coding variants. Engineered variants were transiently expressed in ND7/23 cells and whole-cell voltage clamp experiments were conducted to elucidate their functional properties. Resequencing SCN10A identified 18 heterozygous rare coding variants (minor allele frequency ≤1%) in 18 (6.6%) AF probands. Four probands were carriers of two rare variants each and 14 were carriers of one coding variant. Based on evidence of co-segregation, initial assessment of functional importance, and presence in ≥1 AF proband, three variants (417delK, A1886V, and the compound variant Y158D-R814H) were selected for functional studies. The 417delK variant displayed near absent current while A1886V and Y158D-R814H exhibited enhanced peak and late ( I Na-L) sodium currents; both Y158D and R818H individually contributed to this phenotype. Conclusion Rare SCN10A variants encoding Nav1.8 were identified in 6.6% of patients with early onset AF. In-vitro electrophysiological studies demonstrated profoundly altered function in 3/3 high-priority variants. Collectively, these data strongly support the hypothesis that rare SCN10A variants may contribute to AF susceptibility.