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Carol Ann Remme - One of the best experts on this subject based on the ideXlab platform.
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enhanced late Sodium current underlies pro arrhythmic intracellular Sodium and calcium dysregulation in murine Sodium Channelopathy
International Journal of Cardiology, 2018Co-Authors: Mathilde R Rivaud, Luiz Belardinelli, Leander Beekman, Arie O. Verkerk, Connie R Bezzina, Antonius Baartscheer, Sridharan Rajamani, Carol Ann RemmeAbstract:Abstract Background Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late Sodium current (INa,L) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation. We here investigated the dynamic relation between INa,L, intracellular Sodium ([Na+]i) and calcium ([Ca2+]i) homeostasis and pro-arrhythmic events in the setting of a SCN5A mutation. Methods and results Wild-type (WT) and Scn5a1798insD/+ (MUT) mice (age 3–5 months) carrying the murine homolog of the SCN5A-1795insD mutation on two distinct genetic backgrounds (FVB/N and 129P2) were studied. [Na+]i, [Ca2+]i and Ca2+ transient amplitude were significantly increased in 129P2-MUT myocytes as compared to WT, but not in FVB/N-MUT. Accordingly, INa,L wassignificantly more enhanced in 129P2-MUT than in FVB/N-MUT myocytes, consistent with a dose-dependent correlation. Quantitative RT-PCR analysis revealed intrinsic differences in mRNA expression levels of the Sodium/potassium pump, the Sodium/hydrogen exchanger, and Sodium‑calcium exchanger between the two mouse strains. The rate of increase in [Na+]i, [Ca2+]i and Ca2+ transient amplitude following the application of the Na+/K+-ATPase inhibitor ouabain was significantly greater in 129P2-MUT than in 129P2-WT myocytes and was normalized by the INa,L inhibitor ranolazine. Furthermore, ranolazine decreased the incidence of pro-arrhythmic calcium after-transients elicited in 129P2-MUT myocytes. Conclusions In this study we established a causal link between the magnitude of INa,L, extent of Na+ and Ca2+ dysregulation, and incidence of pro-arrhythmic events in murine Scn5a1798insD/+ myocytes. Furthermore, our findings provide mechanistic insight into the anti-arrhythmic potential of pharmacological inhibition of INa,L in patients with LQT3 syndrome.
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cardiac Sodium Channelopathy associated with scn5a mutations electrophysiological molecular and genetic aspects
The Journal of Physiology, 2013Co-Authors: Carol Ann RemmeAbstract:Over the last two decades, an increasing number of SCN5A mutations have been described in patients with long QT syndrome type 3 (LQT3), Brugada syndrome, (progressive) conduction disease, sick sinus syndrome, atrial standstill, atrial fibrillation, dilated cardiomyopathy, and sudden infant death syndrome (SIDS). Combined genetic, electrophysiological and molecular studies have provided insight into the dysfunction and dysregulation of the cardiac Sodium channel in the setting of SCN5A mutations identified in patients with these inherited arrhythmia syndromes. However, risk stratification and patient management is hindered by the reduced penetrance and variable disease expressivity in Sodium channelopathies. Furthermore, various SCN5A-related arrhythmia syndromes are known to display mixed phenotypes known as cardiac Sodium channel overlap syndromes. Determinants of variable disease expressivity, including genetic background and environmental factors, are suspected but still largely unknown. Moreover, it has become increasingly clear that Sodium channel function and regulation is more complicated than previously assumed, and the Sodium channel may play additional, as of yet unrecognized, roles in cardiac structure and function. Development of cardiac structural abnormalities secondary to SCN5A mutations has been reported, but the clinical relevance and underlying mechanisms are unclear. Increased insight into these issues would enable a major next step in research related to cardiac Sodium channel disease, ultimately enabling improved diagnosis, risk stratification and treatment strategies.
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pluripotent stem cell models of a cardiac Sodium Channelopathy
Biophysical Journal, 2012Co-Authors: Simona Casini, Carol Ann Remme, Arie O. Verkerk, Connie R Bezzina, Arthur A M Wilde, Richard P Davis, Cathelijne W Van Den Berg, Cheryl Dambrot, Dorien Wardvan Oostwaard, Christian FreundAbstract:Mutations in the gene encoding the cardiac Sodium (Na+) channel, SCN5A, have been implicated in multiple arrhythmia syndromes, such as long-QT syndrome type 3 (LQT3) and Brugada syndrome (BrS). Carriers of the SCN5A-1795insD mutation exhibit both features of LQT3 and BrS. Transgenic mice carrying the mouse equivalent (1798insD) of the human SCN5A-1795insD mutation recapitulate the electrophysiological characteristics observed in patients. Recent advances in the pluripotent stem cells (PSCs) field have created new opportunities for modelling cardiac genetic diseases. However, it is unclear whether PSCs can model genetic disorders affecting the cardiac Na+ channel due to the immaturity of the PSC- derived cardiomyocytes (CMs). To address this issue, we generated multiple PSC lines containing a Na+ channel mutation causing a cardiac Na+ channel overlap syndrome.Methods: We generated mouse embryonic stem cells (mESCs) and mouse induced pluripotent stem cells (miPSCs), both wild type (scn5a-wt) and carrying the heterozygous scn5a-1798insD mutation (scn5a-het). Human iPSCs (hiPSCs) both from a patient carrying the SCN5A-1795insDmutation (SCN5A-het) and an unaffected individual were also created. Finally, human and mouse PSCs were differentiated into CMs and used for patch-clamp experiments.Results: In both mESC and miPSC cardiomyocytes, scn5a-het showed a significant decreased INa density compared to Scn5a-wt, while Na+ channel gating properties were unchanged. Action potential (AP) measurements revealed a reduced upstroke velocity and longer AP duration in Scn5a-het myocytes. These characteristics reflected those in primary CMs isolated from adult Scn5a-het mice. Finally, SCN5A-het myocytes revealed similar changes to those observed in the mouse PSC-CMs.Conclusions: Here we demonstrated that ESC- and iPSC derived cardiomyocytes recapitulate the electrophysiological characteristics of a cardiac Na+ channel mutation associated with both LQT3 and BrS and that the immaturity of PSC cardiomyocytes does not preclude their use as an accurate disease model.
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genetically determined differences in Sodium current characteristics modulate conduction disease severity in mice with cardiac Sodium Channelopathy
Circulation Research, 2009Co-Authors: Carol Ann Remme, Brendon P Scicluna, Ahmad S Amin, Sandra Van Brunschot, Vera H M Deneer, Catherine Chevalier, Leander Beekman, Arie O. Verkerk, Fumitaka Oyama, Haruko MiyazakiAbstract:Conduction slowing of the electric impulse that drives the heartbeat may evoke lethal cardiac arrhythmias. Mutations in SCN5A , which encodes the pore-forming cardiac Sodium channel α subunit, are associated with familial arrhythmia syndromes based on conduction slowing. However, disease severity among mutation carriers is highly variable. We hypothesized that genetic modifiers underlie the variability in conduction slowing and disease severity. With the aim of identifying such modifiers, we studied the Scn5a 1798insD/+ mutation in 2 distinct mouse strains, FVB/N and 129P2. In 129P2 mice, the mutation resulted in more severe conduction slowing particularly in the right ventricle (RV) compared to FVB/N. Pan-genomic mRNA expression profiling in the 2 mouse strains uncovered a drastic reduction in mRNA encoding the Sodium channel auxiliary subunit β4 ( Scn4b ) in 129P2 mice compared to FVB/N. This corresponded to low to undetectable β4 protein levels in 129P2 ventricular tissue, whereas abundant β4 protein was detected in FVB/N. Sodium current measurements in isolated myocytes from the 2 mouse strains indicated that Sodium channel activation in myocytes from 129P2 mice occurred at more positive potentials compared to FVB/N. Using computer simulations, this difference in activation kinetics was predicted to explain the observed differences in conduction disease severity between the 2 strains. In conclusion, genetically determined differences in Sodium current characteristics on the myocyte level modulate disease severity in cardiac Sodium channelopathies. In particular, the Sodium channel subunit β4 ( SCN4B ) may constitute a potential genetic modifier of conduction and cardiac Sodium channel disease.
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cardiac Sodium channel overlap syndromes different faces of scn5a mutations
Trends in Cardiovascular Medicine, 2008Co-Authors: Carol Ann Remme, Arthur A M Wilde, Connie R BezzinaAbstract:Cardiac Sodium channel dysfunction caused by mutations in the SCN5A gene is associated with a number of relatively uncommon arrhythmia syndromes, including long-QT syndrome type 3 (LQT3), Brugada syndrome, conduction disease, sinus node dysfunction, and atrial standstill, which potentially lead to fatal arrhythmias in relatively young individuals. Although these various arrhythmia syndromes were originally considered separate entities, recent evidence indicates more overlap in clinical presentation and biophysical defects of associated mutant channels than previously appreciated. Various SCN5A mutations are now known to present with mixed phenotypes, a presentation that has become known as "overlap syndrome of cardiac Sodium Channelopathy." In many cases, multiple biophysical defects of single SCN5A mutations are suspected to underlie the overlapping clinical manifestations. Here, we provide an overview of current knowledge on SCN5A mutations associated with Sodium channel overlap syndromes and discuss a possible role for modifiers in determining disease expressivity in the individual patient.
Takeshi Harita - One of the best experts on this subject based on the ideXlab platform.
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abstract 17754 human ipsc derived myocyte mmodel of scn5a d1275n related cardiac Sodium Channelopathy reveals diminished Sodium currents resulting from enhanced protein degradation
Circulation, 2017Co-Authors: Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi Harita, Yuta YamamotoAbstract:Introduction: The SCN5A gene encodes the α subunit of the cardiac Sodium (Na+) channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with...
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development of a patient derived induced pluripotent stem cell model for the investigation of scn5a d1275n related cardiac Sodium Channelopathy
Circulation, 2017Co-Authors: Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi HaritaAbstract:BACKGROUND TheSCN5Agene encodes the α subunit of the cardiac voltage-gated Sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum Sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type. Second, we generated human-induced pluripotent stem cells (hiPSCs) from a 24-year-old female who carried heterozygousSCN5A-D1275N and analyzed the differentiated cardiomyocytes (CMs). AlthoughSCN5Atranscript levels were equivalent between D1275N and control hiPSC-CMs, both the total amount of NaV1.5 and the membrane fractions were reduced approximately half in the D1275N cells, which were rescued by the proteasome inhibitor MG132 treatment. Electrophysiological assays revealed that maximum Sodium conductance was reduced to approximately half of that in control hiPSC-CMs in the D1275N cells, and maximum upstroke velocity of action potential was lower in D1275N, which was consistent with the reduced protein level of NaV1.5. CONCLUSIONS This study successfully demonstrated diminished Sodium currents resulting from lower NaV1.5 protein levels, which is dependent on proteasomal degradation, using a hiPSC-based model forSCN5A-D1275N-related Sodium Channelopathy.
Yimin Wuriyanghai - One of the best experts on this subject based on the ideXlab platform.
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abstract 17754 human ipsc derived myocyte mmodel of scn5a d1275n related cardiac Sodium Channelopathy reveals diminished Sodium currents resulting from enhanced protein degradation
Circulation, 2017Co-Authors: Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi Harita, Yuta YamamotoAbstract:Introduction: The SCN5A gene encodes the α subunit of the cardiac Sodium (Na+) channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with...
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development of a patient derived induced pluripotent stem cell model for the investigation of scn5a d1275n related cardiac Sodium Channelopathy
Circulation, 2017Co-Authors: Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi HaritaAbstract:BACKGROUND TheSCN5Agene encodes the α subunit of the cardiac voltage-gated Sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum Sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type. Second, we generated human-induced pluripotent stem cells (hiPSCs) from a 24-year-old female who carried heterozygousSCN5A-D1275N and analyzed the differentiated cardiomyocytes (CMs). AlthoughSCN5Atranscript levels were equivalent between D1275N and control hiPSC-CMs, both the total amount of NaV1.5 and the membrane fractions were reduced approximately half in the D1275N cells, which were rescued by the proteasome inhibitor MG132 treatment. Electrophysiological assays revealed that maximum Sodium conductance was reduced to approximately half of that in control hiPSC-CMs in the D1275N cells, and maximum upstroke velocity of action potential was lower in D1275N, which was consistent with the reduced protein level of NaV1.5. CONCLUSIONS This study successfully demonstrated diminished Sodium currents resulting from lower NaV1.5 protein levels, which is dependent on proteasomal degradation, using a hiPSC-based model forSCN5A-D1275N-related Sodium Channelopathy.
Mamoru Hayano - One of the best experts on this subject based on the ideXlab platform.
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abstract 17754 human ipsc derived myocyte mmodel of scn5a d1275n related cardiac Sodium Channelopathy reveals diminished Sodium currents resulting from enhanced protein degradation
Circulation, 2017Co-Authors: Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi Harita, Yuta YamamotoAbstract:Introduction: The SCN5A gene encodes the α subunit of the cardiac Sodium (Na+) channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with...
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development of a patient derived induced pluripotent stem cell model for the investigation of scn5a d1275n related cardiac Sodium Channelopathy
Circulation, 2017Co-Authors: Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi HaritaAbstract:BACKGROUND TheSCN5Agene encodes the α subunit of the cardiac voltage-gated Sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum Sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type. Second, we generated human-induced pluripotent stem cells (hiPSCs) from a 24-year-old female who carried heterozygousSCN5A-D1275N and analyzed the differentiated cardiomyocytes (CMs). AlthoughSCN5Atranscript levels were equivalent between D1275N and control hiPSC-CMs, both the total amount of NaV1.5 and the membrane fractions were reduced approximately half in the D1275N cells, which were rescued by the proteasome inhibitor MG132 treatment. Electrophysiological assays revealed that maximum Sodium conductance was reduced to approximately half of that in control hiPSC-CMs in the D1275N cells, and maximum upstroke velocity of action potential was lower in D1275N, which was consistent with the reduced protein level of NaV1.5. CONCLUSIONS This study successfully demonstrated diminished Sodium currents resulting from lower NaV1.5 protein levels, which is dependent on proteasomal degradation, using a hiPSC-based model forSCN5A-D1275N-related Sodium Channelopathy.
Connie R Bezzina - One of the best experts on this subject based on the ideXlab platform.
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enhanced late Sodium current underlies pro arrhythmic intracellular Sodium and calcium dysregulation in murine Sodium Channelopathy
International Journal of Cardiology, 2018Co-Authors: Mathilde R Rivaud, Luiz Belardinelli, Leander Beekman, Arie O. Verkerk, Connie R Bezzina, Antonius Baartscheer, Sridharan Rajamani, Carol Ann RemmeAbstract:Abstract Background Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late Sodium current (INa,L) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation. We here investigated the dynamic relation between INa,L, intracellular Sodium ([Na+]i) and calcium ([Ca2+]i) homeostasis and pro-arrhythmic events in the setting of a SCN5A mutation. Methods and results Wild-type (WT) and Scn5a1798insD/+ (MUT) mice (age 3–5 months) carrying the murine homolog of the SCN5A-1795insD mutation on two distinct genetic backgrounds (FVB/N and 129P2) were studied. [Na+]i, [Ca2+]i and Ca2+ transient amplitude were significantly increased in 129P2-MUT myocytes as compared to WT, but not in FVB/N-MUT. Accordingly, INa,L wassignificantly more enhanced in 129P2-MUT than in FVB/N-MUT myocytes, consistent with a dose-dependent correlation. Quantitative RT-PCR analysis revealed intrinsic differences in mRNA expression levels of the Sodium/potassium pump, the Sodium/hydrogen exchanger, and Sodium‑calcium exchanger between the two mouse strains. The rate of increase in [Na+]i, [Ca2+]i and Ca2+ transient amplitude following the application of the Na+/K+-ATPase inhibitor ouabain was significantly greater in 129P2-MUT than in 129P2-WT myocytes and was normalized by the INa,L inhibitor ranolazine. Furthermore, ranolazine decreased the incidence of pro-arrhythmic calcium after-transients elicited in 129P2-MUT myocytes. Conclusions In this study we established a causal link between the magnitude of INa,L, extent of Na+ and Ca2+ dysregulation, and incidence of pro-arrhythmic events in murine Scn5a1798insD/+ myocytes. Furthermore, our findings provide mechanistic insight into the anti-arrhythmic potential of pharmacological inhibition of INa,L in patients with LQT3 syndrome.
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pluripotent stem cell models of a cardiac Sodium Channelopathy
Biophysical Journal, 2012Co-Authors: Simona Casini, Carol Ann Remme, Arie O. Verkerk, Connie R Bezzina, Arthur A M Wilde, Richard P Davis, Cathelijne W Van Den Berg, Cheryl Dambrot, Dorien Wardvan Oostwaard, Christian FreundAbstract:Mutations in the gene encoding the cardiac Sodium (Na+) channel, SCN5A, have been implicated in multiple arrhythmia syndromes, such as long-QT syndrome type 3 (LQT3) and Brugada syndrome (BrS). Carriers of the SCN5A-1795insD mutation exhibit both features of LQT3 and BrS. Transgenic mice carrying the mouse equivalent (1798insD) of the human SCN5A-1795insD mutation recapitulate the electrophysiological characteristics observed in patients. Recent advances in the pluripotent stem cells (PSCs) field have created new opportunities for modelling cardiac genetic diseases. However, it is unclear whether PSCs can model genetic disorders affecting the cardiac Na+ channel due to the immaturity of the PSC- derived cardiomyocytes (CMs). To address this issue, we generated multiple PSC lines containing a Na+ channel mutation causing a cardiac Na+ channel overlap syndrome.Methods: We generated mouse embryonic stem cells (mESCs) and mouse induced pluripotent stem cells (miPSCs), both wild type (scn5a-wt) and carrying the heterozygous scn5a-1798insD mutation (scn5a-het). Human iPSCs (hiPSCs) both from a patient carrying the SCN5A-1795insDmutation (SCN5A-het) and an unaffected individual were also created. Finally, human and mouse PSCs were differentiated into CMs and used for patch-clamp experiments.Results: In both mESC and miPSC cardiomyocytes, scn5a-het showed a significant decreased INa density compared to Scn5a-wt, while Na+ channel gating properties were unchanged. Action potential (AP) measurements revealed a reduced upstroke velocity and longer AP duration in Scn5a-het myocytes. These characteristics reflected those in primary CMs isolated from adult Scn5a-het mice. Finally, SCN5A-het myocytes revealed similar changes to those observed in the mouse PSC-CMs.Conclusions: Here we demonstrated that ESC- and iPSC derived cardiomyocytes recapitulate the electrophysiological characteristics of a cardiac Na+ channel mutation associated with both LQT3 and BrS and that the immaturity of PSC cardiomyocytes does not preclude their use as an accurate disease model.
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cardiac Sodium channel overlap syndromes different faces of scn5a mutations
Trends in Cardiovascular Medicine, 2008Co-Authors: Carol Ann Remme, Arthur A M Wilde, Connie R BezzinaAbstract:Cardiac Sodium channel dysfunction caused by mutations in the SCN5A gene is associated with a number of relatively uncommon arrhythmia syndromes, including long-QT syndrome type 3 (LQT3), Brugada syndrome, conduction disease, sinus node dysfunction, and atrial standstill, which potentially lead to fatal arrhythmias in relatively young individuals. Although these various arrhythmia syndromes were originally considered separate entities, recent evidence indicates more overlap in clinical presentation and biophysical defects of associated mutant channels than previously appreciated. Various SCN5A mutations are now known to present with mixed phenotypes, a presentation that has become known as "overlap syndrome of cardiac Sodium Channelopathy." In many cases, multiple biophysical defects of single SCN5A mutations are suspected to underlie the overlapping clinical manifestations. Here, we provide an overview of current knowledge on SCN5A mutations associated with Sodium channel overlap syndromes and discuss a possible role for modifiers in determining disease expressivity in the individual patient.