Abstract 5346: Regulation of Cardiac Na + Current by Pyridine Nucleotides: A Possible Explanation of Glycerol-3-Phosphate Dehydrogenase-Linked Brugada Syndrome

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Shamarendra Sanyal ◽  
Iman S Gurung ◽  
Arnold E Pfahnl ◽  
Lijuan L Shang ◽  
Shahriar Iravanian ◽  
...  
Keyword(s):  
Mouse Model ◽  
Brugada Syndrome ◽  
Fluorescent Microscopy ◽  
Gene Mutations ◽  
Oxidase Inhibitor ◽  
Pyridine Nucleotides ◽  
Programmed Electrical Stimulation ◽  
Amino Acid Homology ◽  
Cardiac Sodium Channel ◽  
Glycerol 3 Phosphate Dehydrogenase

Recently, glycerol-3-phosphate dehydrogenase 1-like (GPD1-L) gene mutations have been shown to reduce cardiac Na + current and cause Brugada Syndrome (BrS). The glycerol-3-phosphate dehydrogenase (GPD) family of genes is involved in nicotinamide adenine dinucleotides (NAD)-dependent energy metabolism, and GDP1-L has >80% amino acid homology with GPD. Therefore, we tested whether mutations in GPD1-L could be acting through NAD (H) to alter Na + current. Human embryonic kidney (HEK) cells stably expressing the human cardiac sodium channel (SCN5A) were used to assess the effects of wild-type (WT) and mutant (MT) GPD1-L on cellular NAD(H) and the effects of NAD(H) on Na + current. A mouse model of BrS was used to assess the effect of reduced NAD + on arrhythmic risk. MT GPD1-L raised cellular NADH level by 4.3 fold (p<0.01) and reduced Na + current by 69.9% (p<0.01). Extracellular NADH (300 μM) raised cellular NADH by 5.3 fold and decreased whole cell peak conductance by 71.4% (p<0.001). Extracellular NAD + (300 μM) raised conductance by 30.3% (p< 0.001). Fluorescent microscopy showed parallel changes in membrane-associated, GFP-tagged Na + channels. Intracellular application of NADH or NAD + resulted in an immediate change in Na + current of −55.5% (p < 0.01) and +66.6% (p < 0.01), respectively. External NAD + could prevent the reduction in Na + current caused by MT GPD1-L. Apocynin (100 μM), an NAD(P)H oxidase inhibitor, or the reducing agent, dithiothreitol (DTT), prevented the NADH-induced reduction in Na + current (p < 0.01). Application of 100 μM NAD + to a mouse model of BrS reduced the programmed electrical stimulation induced ventricular tachycardia. GPD1-L mutations may cause BrS through alterations in cellular NAD(H), and NAD + might represent a novel treatment for BrS.

P1597Two novel mutations in SCN5A gene cause enhanced inactivation and lead to Brugada syndrome

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
A Zaytseva ◽  
A V Karpushev ◽  
A V Karpushev ◽  
Y Fomicheva ◽  
Y Fomicheva ◽  
...  
Keyword(s):  
Steady State ◽  
Sodium Channel ◽  
Brugada Syndrome ◽  
Slow Inactivation ◽  
Fast Inactivation ◽  
Novel Mutations ◽  
Patch Clamp Technique ◽  
Inactivation Curve ◽  
Voltage Gated ◽  
Cardiac Sodium Channel

Abstract Background Mutations in gene SCN5A, encoding cardiac potential-dependent sodium channel Nav1.5, are associated with various arrhythmogenic disorders among which the Brugada syndrome (BrS) and the Long QT syndrome (LQT) are the best characterized. BrS1 is associated with sodium channel dysfunction, which can be reflected by decreased current, impaired activation and enhanced inactivation. We found two novel mutations in our patients with BrS and explored their effect on fast and slow inactivation of cardiac sodium channel. Purpose The aim of this study was to investigate the effect of BrS (Y739D, L1582P) mutations on different inactivation processes in in vitro model. Methods Y739D and L1582P substitutions were introduced in SCN5A cDNA using site-directed mutagenesis. Sodium currents were recorded at room temperature in transfected HEK293-T cells using patch-clamp technique with holding potential −100 mV. In order to access the fast steady-state inactivation curve we used double-pulse protocol with 10 ms prepulses. To analyze voltage-dependence of slow inactivation we used two-pulse protocol with 10s prepulse, 20ms test pulse and 25ms interpulse at −100mV to allow recovery from fast inactivation. Electrophysiological measurements are presented as mean ±SEM. Results Y739D mutation affects highly conserved tyrosine 739 among voltage-gated sodium and calcium channels in the segment IIS2. Mutation L1582P located in the loop IVS4-S5, and leucine in this position is not conserved among voltage-gated channels superfamily. We have shown that Y739D leads to significant changes in both fast and slow inactivation, whereas L1582P enhanced slow inactivation only. Steady-state fast inactivation for Y739D was shifted on 8.9 mV towards more negative potentials compare with that for WT, while L1582P did not enhanced fast inactivation (V1/2 WT: −62.8±1.7 mV; Y739D: −71.7±2.3 mV; L1582P: −58.7±1.4 mV). Slow inactivation was increased for both substitutions (INa (+20mV)/INa (−100mV) WT: 0.45±0.03; Y739D: 0,34±0.09: L1582P: 0.38±0.04). Steady-state fast inactivation Conclusions Both mutations, observed in patients with Brugada syndrome, influence on the slow inactivation process. Enhanced fast inactivation was shown only for Y739D mutant. The more dramatic alterations in sodium channel biophysical characteristics are likely linked with mutated residue conservativity. Acknowledgement/Funding RSF #17-15-01292

Differential effects of cardiac sodium channel mutations on initiation of ventricular arrhythmias in patients with Brugada syndrome

Heart Rhythm ◽  
2009 ◽  
Vol 6 (4) ◽  
pp. 487-492 ◽  
Author(s):  
Hiroshi Morita ◽  
Satoshi Nagase ◽  
Daiji Miura ◽  
Aya Miura ◽  
Shigeki Hiramatsu ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Brugada Syndrome ◽  
Ventricular Arrhythmias ◽  
Differential Effects ◽  
Cardiac Sodium Channel

scholarly journals A cardiac sodium channel mutation identified in Brugada syndrome associated with atrial standstill

2004 ◽  
Vol 255 (1) ◽  
pp. 137-142 ◽  
Author(s):  
N. Takehara ◽  
N. Makita ◽  
J. Kawabe ◽  
N. Sato ◽  
Y. Kawamura ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Brugada Syndrome ◽  
Cardiac Sodium Channel ◽  
Channel Mutation ◽  
Sodium Channel Mutation

scholarly journals Compound heterozygous SCN5A gene mutations in asymptomatic Brugada syndrome child

2012 ◽  
Vol 2 (1) ◽  
pp. 11 ◽  
Author(s):  
Elena Sommariva ◽  
Matteo Vatta ◽  
Yutao Xi ◽  
Simone Sala ◽  
Tomohiko Ai ◽  
...  
Keyword(s):  
Brugada Syndrome ◽  
Gene Mutations ◽  
Compound Heterozygous ◽  
Scn5a Gene ◽  
Syndrome Child

scholarly journals Novel SCN5A and GPD1L Variants Identified in Two Unrelated Han-Chinese Patients With Clinically Suspected Brugada Syndrome

2021 ◽  
Vol 8 ◽  
Author(s):  
Meng Yuan ◽  
Yi Guo ◽  
Hong Xia ◽  
Hongbo Xu ◽  
Hao Deng ◽  
...  
Keyword(s):  
Brugada Syndrome ◽  
Missense Variant ◽  
Han Chinese ◽  
Chinese Patients ◽  
Splicing Variant ◽  
Pathogenic Variants ◽  
Whole Exome ◽  
Gated Channel ◽  
Life Threatening ◽  
Glycerol 3 Phosphate Dehydrogenase

Brugada syndrome (BrS) is a complexly genetically patterned, rare, malignant, life-threatening arrhythmia disorder. It is autosomal dominant in most cases and characterized by identifiable electrocardiographic patterns, recurrent syncope, nocturnal agonal respiration, and other symptoms, including sudden cardiac death. Over the last 2 decades, a great number of variants have been identified in more than 36 pathogenic or susceptibility genes associated with BrS. The present study used the combined method of whole exome sequencing and Sanger sequencing to identify pathogenic variants in two unrelated Han-Chinese patients with clinically suspected BrS. Minigene splicing assay was used to evaluate the effects of the splicing variant. A novel heterozygous splicing variant c.2437-2A&gt;C in the sodium voltage-gated channel alpha subunit 5 gene (SCN5A) and a novel heterozygous missense variant c.161A&gt;T [p.(Asp54Val)] in the glycerol-3-phosphate dehydrogenase 1 like gene (GPD1L) were identified in these two patients with BrS-1 and possible BrS-2, respectively. Minigene splicing assay indicated the deletion of 15 and 141 nucleotides in exon 16, resulting in critical amino acid deletions. These findings expand the variant spectrum of SCN5A and GPD1L, which can be beneficial to genetic counseling and prenatal diagnosis.

Abstract 1111: Embryoinc Stem Cell Derived Cardiovascular Progenitor Cells Improve Function More Than Hemangioblasts in a Mouse Model of Myocardial Infarction

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Eric Adler ◽  
Vincient Chen ◽  
Anne Bystrup ◽  
Wilson Young ◽  
Steve Giovannone ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Stem Cell ◽  
Mouse Model ◽  
Progenitor Cells ◽  
Myocardial Function ◽  
Es Cells ◽  
Fluorescent Microscopy ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ventricular Ejection Fraction

BACKGROUND: Intramyocardial transplantation of stem cells improves left ventricular ejection fraction (EF) in animal studies and preliminary clinical trials. The mechanism may involve either replacement of myocytes or improved vascular supply to existing myocytes. We recently identified an Embyronic Stem cell derived cardiovascular progenitor cell (ES-CPC) that is the common precursor of cardiomyocyte and vascular cell lineages. To determine whether myocyte transplantation improves myocardial function more than angiogenesis alone does, we compared the effect of ES-CPCs to hemangioblasts (vascular/hematopoetic progenitor cells) on EF in a mouse model of myocardial infarction. METHODS: ES-CPC and hemangioblasts were isolated from a doxycycline-responsive, Notch-inducible ES cell line containing Notch 4 cDNA under the control of a tetracycline-inducible promoter. Notch induction of mesoderm-derived ES cells resulted in a CPC phenotype, whereas non-induced cells developed into hemangioblasts. Mice underwent transplantation of 500,000 ES-CPC (n=20), hemangioblasts (n=16), or an equal volume of serum-free media (n=12) 30 minutes after surgically-induced myocardial infarction. All cell lines constitutively expressed green fluorescent protein (GFP). EF was assessed two weeks post-transplantation using 9.4 Tesla MRI. Mice were then euthanized and frozen heart sections were examined using fluorescent microscopy. RESULTS: The mean EF was 59Â ± 15, 46Â ± 17, and 39Â ± 13% in the ES-CPC, hemangioblast, and control groups, respectively (p<0.05 for the differences among all 3 groups; ANOVA). GFP + cells were detected in frozen sections of both the ES-CPC and hemangioblast groups. GFP + cells in ES-CPC treated hearts expressed markers associated with both cardiomyocyte and vascular phenotypes, whereas the GFP + cells in the hemangioblast group expressed markers associated with vascular phenotypes. CONCLUSIONS: Both hemangioblast and ES-CPC transplantation improves EF in a mouse model of myocardial infarction, but ES-CPC transplantation was more effective. This suggests that enhancement of myocardial function by transplantation of both cardiomyocyte and vascular phenotypes exceeds that with vascular phenotypes alone.

scholarly journals Experimental Models of Brugada syndrome

2019 ◽  
Vol 20 (9) ◽  
pp. 2123 ◽  
Author(s):  
Sendfeld ◽  
Selga ◽  
Scornik ◽  
Pérez ◽  
Mills ◽  
...  
Keyword(s):  
Brugada Syndrome ◽  
Experimental Models ◽  
Model Systems ◽  
Patient Specific ◽  
Canine Heart ◽  
Stem Cell Technology ◽  
St Segment Elevation ◽  
St Segment ◽  
Cardiac Sodium Channel ◽  
The Right

Brugada syndrome is an inherited, rare cardiac arrhythmogenic disease, associated with sudden cardiac death. It accounts for up to 20% of sudden deaths in patients without structural cardiac abnormalities. The majority of mutations involve the cardiac sodium channel gene SCN5A and give rise to classical abnormal electrocardiogram with ST segment elevation in the right precordial leads V1 to V3 and a predisposition to ventricular fibrillation. The pathophysiological mechanisms of Brugada syndrome have been investigated using model systems including transgenic mice, canine heart preparations, and expression systems to study different SCN5A mutations. These models have a number of limitations. The recent development of pluripotent stem cell technology creates an opportunity to study cardiomyocytes derived from patients and healthy individuals. To date, only a few studies have been done using Brugada syndrome patient-specific iPS-CM, which have provided novel insights into the mechanisms and pathophysiology of Brugada syndrome. This review provides an evaluation of the strengths and limitations of each of these model systems and summarizes the key mechanisms that have been identified to date.

scholarly journals Lidocaine-Induced Brugada Syndrome Phenotype Linked to a Novel Double Mutation in the Cardiac Sodium Channel

2008 ◽  
Vol 103 (4) ◽  
pp. 396-404 ◽  
Author(s):  
Hector M. Barajas-Martínez ◽  
Dan Hu ◽  
Jonathan M. Cordeiro ◽  
Yuesheng Wu ◽  
Richard J. Kovacs ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Brugada Syndrome ◽  
Double Mutation ◽  
Cardiac Sodium Channel

scholarly journals The cytoplasmic NPM mutant induces myeloproliferation in a transgenic mouse model

Blood ◽  
2010 ◽  
Vol 115 (16) ◽  
pp. 3341-3345 ◽  
Author(s):  
Ke Cheng ◽  
Paolo Sportoletti ◽  
Keisuke Ito ◽  
John G. Clohessy ◽  
Julie Teruya-Feldstein ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Mouse Model ◽  
Transgenic Mice ◽  
Transgenic Mouse ◽  
Myeloid Leukemia ◽  
Gene Mutations ◽  
Transgenic Mouse Model ◽  
Acute Myeloid

Abstract Although NPM1 gene mutations leading to aberrant cytoplasmic expression of nucleophosmin (NPMc+) are the most frequent genetic lesions in acute myeloid leukemia, there is yet no experimental model demonstrating their oncogenicity in vivo. We report the generation and characterization of a transgenic mouse model expressing the most frequent human NPMc+ mutation driven by the myeloid-specific human MRP8 promoter (hMRP8-NPMc+). In parallel, we generated a similar wild-type NPM trans-genic model (hMRP8-NPM). Interestingly, hMRP8-NPMc+ transgenic mice developed myeloproliferation in bone marrow and spleen, whereas nontransgenic littermates and hMRP8-NPM transgenic mice remained disease free. These findings provide the first in vivo evidence indicating that NPMc+ confers a proliferative advantage in the myeloid lineage. No spontaneous acute myeloid leukemia was found in hMPR8-NPMc+ or hMRP8-NPM mice. This model will also aid in the development of therapeutic regimens that specifically target NPMc+.

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