Zoltan Varga1, Wandi Zhu1, Angela R Schubert1, Jennifer L Pardieck1, Arie Krumholz1, Eric J Hsu1, Mark A Zaydman1, Jianmin Cui1, Jonathan R Silva2. 1. From the Department of Biomedical Engineering, Washington University in St. Louis, MO (Z.V., W.Z., A.R.S., J.L.P., A.K., E.J.H., M.A.Z., J.C., J.R.S.); and MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary (Z.V.). 2. From the Department of Biomedical Engineering, Washington University in St. Louis, MO (Z.V., W.Z., A.R.S., J.L.P., A.K., E.J.H., M.A.Z., J.C., J.R.S.); and MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary (Z.V.). jonsilva@wustl.edu.
Abstract
BACKGROUND: Dysregulation of voltage-gated cardiac Na(+) channels (NaV1.5) by inherited mutations, disease-linked remodeling, and drugs causes arrhythmias. The molecular mechanisms whereby the NaV1.5 voltage-sensing domains (VSDs) are perturbed to pathologically or therapeutically modulate Na(+) current (INa) have not been specified. Our aim was to correlate INa kinetics with conformational changes within the 4 (DI-DIV) VSDs to define molecular mechanisms of NaV1.5 modulation. METHOD AND RESULTS: Four NaV1.5 constructs were created to track the voltage-dependent kinetics of conformational changes within each VSD, using voltage-clamp fluorometry. Each VSD displayed unique kinetics, consistent with distinct roles in determining INa. In particular, DIII-VSD deactivation kinetics were modulated by depolarizing pulses with durations in the intermediate time domain that modulates late INa. We then used the DII-VSD construct to probe the molecular pathology of 2 Brugada syndrome mutations (A735V and G752R). A735V shifted DII-VSD voltage dependence to depolarized potentials, whereas G752R significantly slowed DII-VSD kinetics. Both mutations slowed INa activation, although DII-VSD activation occurred at higher potentials (A735V) or at later times (G752R) than ionic current activation, indicating that the DII-VSD allosterically regulates the rate of INa activation and myocyte excitability. CONCLUSIONS: Our results reveal novel mechanisms whereby the NaV1.5 VSDs regulate channel activation and inactivation. The ability to distinguish distinct molecular mechanisms of proximal Brugada syndrome mutations demonstrates the potential of these methods to reveal how inherited mutations, post-translational modifications, and antiarrhythmic drugs alter NaV1.5 at the molecular level.
BACKGROUND: Dysregulation of voltage-gated cardiac Na(+) channels (NaV1.5) by inherited mutations, disease-linked remodeling, and drugs causes arrhythmias. The molecular mechanisms whereby the NaV1.5 voltage-sensing domains (VSDs) are perturbed to pathologically or therapeutically modulate Na(+) current (INa) have not been specified. Our aim was to correlate INa kinetics with conformational changes within the 4 (DI-DIV) VSDs to define molecular mechanisms of NaV1.5 modulation. METHOD AND RESULTS: Four NaV1.5 constructs were created to track the voltage-dependent kinetics of conformational changes within each VSD, using voltage-clamp fluorometry. Each VSD displayed unique kinetics, consistent with distinct roles in determining INa. In particular, DIII-VSD deactivation kinetics were modulated by depolarizing pulses with durations in the intermediate time domain that modulates late INa. We then used the DII-VSD construct to probe the molecular pathology of 2 Brugada syndrome mutations (A735V and G752R). A735V shifted DII-VSD voltage dependence to depolarized potentials, whereas G752R significantly slowed DII-VSD kinetics. Both mutations slowed INa activation, although DII-VSD activation occurred at higher potentials (A735V) or at later times (G752R) than ionic current activation, indicating that the DII-VSD allosterically regulates the rate of INa activation and myocyte excitability. CONCLUSIONS: Our results reveal novel mechanisms whereby the NaV1.5 VSDs regulate channel activation and inactivation. The ability to distinguish distinct molecular mechanisms of proximal Brugada syndrome mutations demonstrates the potential of these methods to reveal how inherited mutations, post-translational modifications, and antiarrhythmic drugs alter NaV1.5 at the molecular level.
Authors: Huimin Chen; Syed S Ahsan; Mitk'El B Santiago-Berrios; Hector D Abruña; Watt W Webb Journal: J Am Chem Soc Date: 2010-06-02 Impact factor: 15.419
Authors: Deborah L Capes; Manoel Arcisio-Miranda; Brian W Jarecki; Robert J French; Baron Chanda Journal: Proc Natl Acad Sci U S A Date: 2012-01-30 Impact factor: 11.205
Authors: Kathryn E Mangold; Brittany D Brumback; Paweorn Angsutararux; Taylor L Voelker; Wandi Zhu; Po Wei Kang; Jonathan D Moreno; Jonathan R Silva Journal: Channels (Austin) Date: 2017-09-21 Impact factor: 2.581
Authors: Hong-Gang Wang; Wandi Zhu; Ronald J Kanter; Jonathan R Silva; Christina Honeywell; Robert M Gow; Geoffrey S Pitt Journal: J Mol Cell Cardiol Date: 2016-01-19 Impact factor: 5.000
Authors: Quinton Banks; Hugo Bibollet; Minerva Contreras; Daniel F Bennett; Roger A Bannister; Martin F Schneider; Erick O Hernández-Ochoa Journal: Proc Natl Acad Sci U S A Date: 2021-10-05 Impact factor: 11.205
Authors: Wandi Zhu; Taylor L Voelker; Zoltan Varga; Angela R Schubert; Jeanne M Nerbonne; Jonathan R Silva Journal: J Gen Physiol Date: 2017-07-18 Impact factor: 4.086