scholarly journals Commentary: Peptide-Based Targeting of the L-Type Calcium Channel Corrects the Loss-of-Function Phenotype of Two Novel Mutations of the CACNA1 Gene Associated With Brugada Syndrome

2021 ◽  
Vol 12 ◽  
Author(s):  
Michelle M. Monasky ◽  
Carola Rutigliani ◽  
Emanuele Micaglio ◽  
Carlo Pappone
Keyword(s):  
Calcium Channel ◽  
Brugada Syndrome ◽  
Loss Of Function ◽  
Novel Mutations

Abstract 4413: Accelerated Inactivation of the L-type Calcium due to a Mutation in CACNB2b Underlies the Development of a Brugada ECG Phenotype

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jonathan M Cordeiro ◽  
Mark Marieb ◽  
Ryan Pfeiffer ◽  
Kirstine Calloe ◽  
Elena Burashnikov ◽  
...  
Keyword(s):  
Action Potential ◽  
Calcium Channel ◽  
Brugada Syndrome ◽  
Vasovagal Syncope ◽  
Total Charge ◽  
Loss Of Function ◽  
St Segment Elevation ◽  
St Segment ◽  
Steady State Inactivation ◽  
The Right

Background: Ion channelopathies are responsible for a number of genetic cardiac arrhythmia syndromes. Recent work demonstrated an association between mutations in CACNA1c and CACNB2b, the genes that encode the α and β subunits of the L-type calcium channel, and the Brugada syndrome (BrS). The mutations previously described all caused a loss of function secondary to a major reduction in peak calcium channel current (I Ca ). In the present study we describe a novel CACNB2b mutation associated with BrS in which loss of function was caused by accelerated inactivation of I Ca . Methods and Results: The proband, a 32 yo male, displayed a saddleback ST segment elevation in the right precordial leads that converted to a coved-type ECG following a procainamide challenge. His EP study was positive with double extrastimuli inducing polymorphic VT/VF. He was also diagnosed with vasovagal syncope. Genomic DNA was isolated from blood lymphocytes. All exons and intron borders of 12 ion channel genes were amplified and sequenced. The only mutation uncovered was a missense mutation (T11I) in CACNB2b. The effect of this mutation was studied by expression of WT or T11I CACNB2b in TSA201 cells co-transfected with WT CANCA1c and CACNA2d. Patch clamp analysis showed no difference in I Ca density between WT and T11I (17.9±1.8 vs 22.5±4.3 pA/pF, respectively at +20mV). Similarly, steady-state inactivation and channel recovery was not different between WT and T11I mutant channels. However, both the fast and slow decay of I Ca produced by T11I mutant were significantly faster compared to WT at potentials between −10 to +30 mV, suggesting a reduction in depolarizing current during the course of an action potential. Application of action potential voltage clamp pulses confirmed that T11I total charge was reduced by 42±2.3% compared to WT (p<0.05). Conclusion: We report the first Brugada syndrome mutation in CaCNB2b resulting in accelerated inactivation of the L-type calcium channel. The T11I mutation caused a faster decay of cardiac L-type calcium current but did not significantly alter the magnitude of the peak current. Our results suggest that a reduced total charge carried by I Ca during the plateau of the action potential predisposes to the Brugada phenotype.

scholarly journals Peptide-Based Targeting of the L-Type Calcium Channel Corrects the Loss-of-Function Phenotype of Two Novel Mutations of the CACNA1 Gene Associated With Brugada Syndrome

2021 ◽  
Vol 11 ◽  
Author(s):  
Vittoria Di Mauro ◽  
Paola Ceriotti ◽  
Francesco Lodola ◽  
Nicolò Salvarani ◽  
Jessica Modica ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Brugada Syndrome ◽  
Half Life ◽  
Specific Treatment ◽  
Pharmacological Therapy ◽  
Cardiac Cells ◽  
Hek293 Cells ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Protein Levels

Brugada syndrome (BrS) is an inherited arrhythmogenic disease that may lead to sudden cardiac death in young adults with structurally normal hearts. No pharmacological therapy is available for BrS patients. This situation highlights the urgent need to overcome current difficulties by developing novel groundbreaking curative strategies. BrS has been associated with mutations in 18 different genes of which loss-of-function (LoF) CACNA1C mutations constitute the second most common cause. Here we tested the hypothesis that BrS associated with mutations in the CACNA1C gene encoding the L-type calcium channel (LTCC) pore-forming unit (Cavα1.2) is functionally reverted by administration of a mimetic peptide (MP), which through binding to the LTCC chaperone beta subunit (Cavβ2) restores the physiological life cycle of aberrant LTCCs. Two novel Cavα1.2 mutations associated with BrS were identified in young individuals. Transient transfection in heterologous and cardiac cells showed LoF phenotypes with reduced Ca2+ current (ICa). In HEK293 cells overexpressing the two novel Cavα1.2 mutations, Western blot analysis and cell surface biotinylation assays revealed reduced Cavα1.2 protein levels at the plasma membrane for both mutants. Nano-BRET, Nano-Luciferase assays, and confocal microscopy analyses showed (i) reduced affinity of Cavα1.2 for its Cavβ2 chaperone, (ii) shortened Cavα1.2 half-life in the membrane, and (iii) impaired subcellular localization. Treatment of Cavα1.2 mutant-transfected cells with a cell permeant MP restored channel trafficking and physiologic channel half-life, thereby resulting in ICa similar to wild type. These results represent the first step towards the development of a gene-specific treatment for BrS due to defective trafficking of mutant LTCC.

NR5A1 Loss-of-Function Mutations Lead to 46,XY Partial Gonadal Dysgenesis Phenotype: Report of Three Novel Mutations

2016 ◽  
Vol 10 (4) ◽  
pp. 191-199 ◽  
Author(s):  
Helena C. Fabbri ◽  
Juliana G. Ribeiro de Andrade ◽  
Andréa T. Maciel-Guerra ◽  
Gil Guerra-Júnior ◽  
Maricilda P. de Mello
Keyword(s):  
Gonadal Dysgenesis ◽  
Loss Of Function ◽  
Novel Mutations ◽  
Partial Gonadal Dysgenesis

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

scholarly journals Do Sodium Channel α - α Interactions Contribute to Loss-of-Function Observed in Brugada Syndrome?

2010 ◽  
Vol 98 (3) ◽  
pp. 311a
Author(s):  
Krekwit Shinlapawittayatorn ◽  
Xi Du ◽  
Haiyan Liu ◽  
Eckhard Ficker ◽  
Isabelle Deschenes
Keyword(s):  
Sodium Channel ◽  
Brugada Syndrome ◽  
Loss Of Function

scholarly journals Novel Mutations in Brugada Syndrome

1999 ◽  
Vol 45 (4, Part 2 of 2) ◽  
pp. 32A-32A
Author(s):  
Matteo Vatta ◽  
Ramon Brugada ◽  
Josep Brugada ◽  
Pedro Brugada ◽  
Jimmy Ruiz ◽  
...  
Keyword(s):  
Brugada Syndrome ◽  
Novel Mutations

scholarly journals Generation and characterization of SCN5A loss-of-function mutant mice modeling human brugada syndrome

2013 ◽  
Vol 34 (suppl 1) ◽  
pp. 4556-4556 ◽  
Author(s):  
P. A. Schweizer ◽  
T. Fink ◽  
P. Yampolsky ◽  
C. Seyler ◽  
L. Fabritz ◽  
...  
Keyword(s):  
Brugada Syndrome ◽  
Mutant Mice ◽  
Loss Of Function

scholarly journals Three novel mutations in ASIP associated with black fibre in alpacas (Vicugna pacos)

2011 ◽  
Vol 149 (4) ◽  
pp. 529-538 ◽  
Author(s):  
N. L. FEELEY ◽  
S. BOTTOMLEY ◽  
K. A. MUNYARD
Keyword(s):  
Amino Acids ◽  
Regulatory Region ◽  
Loss Of Function ◽  
Coding Region ◽  
Contributing Factors ◽  
Novel Mutations ◽  
Melanocortin 1 Receptor ◽  
Melanocyte Stimulating Hormone ◽  
Vicugna Pacos ◽  
Probable Loss

SUMMARYThe coding region of the alpaca Agouti signalling protein (ASIP) gene was sequenced. It was determined to be 402 nucleotides long and code for a protein that is 133 amino acids long. Eight mutations were identified in a sample of 15 alpaca, five in the coding region and three in the introns flanking the exons. In silico analysis showed that three of the five mutations in the coding sequence, c.325_381del57, c.292C>T and c.353G>A are probable loss-of-function mutations. The three mutations were strongly associated with black fibre colour, with 0·90 of black alpacas in the current study having two copies of one or another of the mutations. However, not all black animals displayed the putative ‘aa’ genotype, and almost half of the non-black animals did display that genotype. Contributing factors such as regulatory region mutations, interactions of ASIP with melanocortin-1 receptor (MC1R) and α-melanocyte stimulating hormone (α-MSH), the effect of dilution genes and subjective phenotype assignment are discussed. These mutations will allow alpaca breeders to select for or against black, but they do not explain all black phenotypes in this species.

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