Digenic inheritance novel mutations in SCN5a and SNTA1 increase late INa contributing to LQT syndrome

Rou Mu Hu, Bihua Tan, Kate M. Orland, Carmen R. Valdivia, Amber Peterson, Jielin Pu, Jonathan C. Makielski

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

SCN5A and SNTA1 are reported susceptible genes for long QT syndrome (LQTS). This study was designed to elucidate a plausible pathogenic arrhythmia mechanism for the combined novel mutations R800L-SCN5A and A261V-SNTA1 on cardiac sodium channels. A Caucasian family with syncope and marginally prolonged QT interval was screened for LQTS-susceptibility genes and found to harbor the R800L mutation in SCN5A and A261V mutation in SNTA1, and those with both mutations had the strongest clinical phenotype. The mutations were engineered into the most common splice variant of human SCN5A and SNTA1 cDNA, respectively, and sodium current (INa) was characterized in human embryonic kidney 293 cells cotransfected with neuronal nitric oxide synthase (nNOS) and the cardiac isoform of the plasma membrane Ca-ATPase (PMCA4b). Peak INa densities were unchanged for wild-type (WT) and for mutant channels containing R800L-SCN5A, A261V-SNTA1, or R800L-SCN5A plus A261VSNTA1. However, late INa for either single mutant was moderately increased two- to threefold compared with WT. The combined mutations of R800L-SCN5A plus A261V-SNTA1 significantly enhanced the INa late/peak ratio by 5.6-fold compared with WT. The time constants of current decay of combined mutant channel were markedly increased. The gain-of-function effect could be blocked by the NG-monomethyl-L-arginine, a nNOS inhibitor. We conclude that novel mutations in SCN5A and SNTA1 jointly exert a nNOS-dependent gain-of-function on SCN5A channels, which may consequently prolong the action potential duration and lead to LQTS phenotype.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume304
Issue number7
DOIs
StatePublished - Jun 10 2013

Fingerprint

Mutation
Long QT Syndrome
Nitric Oxide Synthase Type I
Phenotype
omega-N-Methylarginine
Sodium Channels
Syncope
Genes
Action Potentials
Adenosine Triphosphatases
Cardiac Arrhythmias
Protein Isoforms
Complementary DNA
Sodium
Cell Membrane
Kidney

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Hu, Rou Mu ; Tan, Bihua ; Orland, Kate M. ; Valdivia, Carmen R. ; Peterson, Amber ; Pu, Jielin ; Makielski, Jonathan C. / Digenic inheritance novel mutations in SCN5a and SNTA1 increase late INa contributing to LQT syndrome. In: American Journal of Physiology - Heart and Circulatory Physiology. 2013 ; Vol. 304, No. 7.
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abstract = "SCN5A and SNTA1 are reported susceptible genes for long QT syndrome (LQTS). This study was designed to elucidate a plausible pathogenic arrhythmia mechanism for the combined novel mutations R800L-SCN5A and A261V-SNTA1 on cardiac sodium channels. A Caucasian family with syncope and marginally prolonged QT interval was screened for LQTS-susceptibility genes and found to harbor the R800L mutation in SCN5A and A261V mutation in SNTA1, and those with both mutations had the strongest clinical phenotype. The mutations were engineered into the most common splice variant of human SCN5A and SNTA1 cDNA, respectively, and sodium current (INa) was characterized in human embryonic kidney 293 cells cotransfected with neuronal nitric oxide synthase (nNOS) and the cardiac isoform of the plasma membrane Ca-ATPase (PMCA4b). Peak INa densities were unchanged for wild-type (WT) and for mutant channels containing R800L-SCN5A, A261V-SNTA1, or R800L-SCN5A plus A261VSNTA1. However, late INa for either single mutant was moderately increased two- to threefold compared with WT. The combined mutations of R800L-SCN5A plus A261V-SNTA1 significantly enhanced the INa late/peak ratio by 5.6-fold compared with WT. The time constants of current decay of combined mutant channel were markedly increased. The gain-of-function effect could be blocked by the NG-monomethyl-L-arginine, a nNOS inhibitor. We conclude that novel mutations in SCN5A and SNTA1 jointly exert a nNOS-dependent gain-of-function on SCN5A channels, which may consequently prolong the action potential duration and lead to LQTS phenotype.",
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Digenic inheritance novel mutations in SCN5a and SNTA1 increase late INa contributing to LQT syndrome. / Hu, Rou Mu; Tan, Bihua; Orland, Kate M.; Valdivia, Carmen R.; Peterson, Amber; Pu, Jielin; Makielski, Jonathan C.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 304, No. 7, 10.06.2013.

Research output: Contribution to journalArticle

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T1 - Digenic inheritance novel mutations in SCN5a and SNTA1 increase late INa contributing to LQT syndrome

AU - Hu, Rou Mu

AU - Tan, Bihua

AU - Orland, Kate M.

AU - Valdivia, Carmen R.

AU - Peterson, Amber

AU - Pu, Jielin

AU - Makielski, Jonathan C.

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AB - SCN5A and SNTA1 are reported susceptible genes for long QT syndrome (LQTS). This study was designed to elucidate a plausible pathogenic arrhythmia mechanism for the combined novel mutations R800L-SCN5A and A261V-SNTA1 on cardiac sodium channels. A Caucasian family with syncope and marginally prolonged QT interval was screened for LQTS-susceptibility genes and found to harbor the R800L mutation in SCN5A and A261V mutation in SNTA1, and those with both mutations had the strongest clinical phenotype. The mutations were engineered into the most common splice variant of human SCN5A and SNTA1 cDNA, respectively, and sodium current (INa) was characterized in human embryonic kidney 293 cells cotransfected with neuronal nitric oxide synthase (nNOS) and the cardiac isoform of the plasma membrane Ca-ATPase (PMCA4b). Peak INa densities were unchanged for wild-type (WT) and for mutant channels containing R800L-SCN5A, A261V-SNTA1, or R800L-SCN5A plus A261VSNTA1. However, late INa for either single mutant was moderately increased two- to threefold compared with WT. The combined mutations of R800L-SCN5A plus A261V-SNTA1 significantly enhanced the INa late/peak ratio by 5.6-fold compared with WT. The time constants of current decay of combined mutant channel were markedly increased. The gain-of-function effect could be blocked by the NG-monomethyl-L-arginine, a nNOS inhibitor. We conclude that novel mutations in SCN5A and SNTA1 jointly exert a nNOS-dependent gain-of-function on SCN5A channels, which may consequently prolong the action potential duration and lead to LQTS phenotype.

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