Jacob M. Kemp
Electrophysiological characterization of the hERG R56Q LQTS variant and targeted rescue by the activator RPR260243
Kemp, Jacob M.; Whittaker, Dominic G.; Venkateshappa, Ravichandra; Pang, Zhao Kai; Johal, Raj; Sergeev, Valentine; Tibbits, Glen F; Mirams, Gary R.; Claydon, Thomas W.
Authors
Dominic G. Whittaker
Ravichandra Venkateshappa
Zhao Kai Pang
Raj Johal
Valentine Sergeev
Glen F Tibbits
Prof. GARY MIRAMS GARY.MIRAMS@NOTTINGHAM.AC.UK
Professor of Mathematical Biology
Thomas W. Claydon
Abstract
Human Ether-à-go-go (hERG) channels contribute to cardiac repolarization, and inherited variants or drug block are associated with long QT syndrome type 2 (LQTS2) and arrhythmia. Therefore, hERG activator compounds present a therapeutic opportunity for targeted treatment of LQTS. However, a limiting concern is over-activation of hERG resurgent current during the action potential and abbreviated repolarization. Activators that slow deactivation gating (type I), such as RPR260243, may enhance repolarizing hERG current during the refractory period, thus ameliorating arrhythmogenicity with reduced early repolarization risk. Here, we show that, at physiological temperature, RPR260243 enhances hERG channel repolarizing currents conducted in the refractory period in response to premature depolarizations. This occurs with little effect on the resurgent hERG current during the action potential. The effects of RPR260243 were particularly evident in LQTS2-associated R56Q mutant channels, whereby RPR260243 restored WT-like repolarizing drive in the early refractory period and diastolic interval, combating attenuated protective currents. In silico kinetic modeling of channel gating predicted little effect of the R56Q mutation on hERG current conducted during the action potential and a reduced repolarizing protection against afterdepolarizations in the refractory period and diastolic interval, particularly at higher pacing rates. These simulations predicted partial rescue from the arrhythmic effects of R56Q by RPR260243 without risk of early repolarization. Our findings demonstrate that the pathogenicity of some hERG variants may result from reduced repolarizing protection during the refractory period and diastolic interval with limited effect on action potential duration, and that the hERG channel activator RPR260243 may provide targeted antiarrhythmic potential in these cases.
Journal Article Type | Article |
---|---|
Acceptance Date | Jul 30, 2021 |
Online Publication Date | Aug 16, 2021 |
Publication Date | Oct 4, 2021 |
Deposit Date | Aug 12, 2021 |
Publicly Available Date | Aug 26, 2021 |
Journal | Journal of General Physiology |
Print ISSN | 0022-1295 |
Electronic ISSN | 1540-7748 |
Peer Reviewed | Peer Reviewed |
Volume | 153 |
Issue | 10 |
Article Number | e202112923 |
DOI | https://doi.org/10.1085/jgp.202112923 |
Public URL | https://nottingham-repository.worktribe.com/output/6013813 |
Publisher URL | https://rupress.org/jgp/article/153/10/e202112923/212555/Electrophysiological-characterization-of-the-hERG |
Files
jgp_202112923
(6.2 Mb)
PDF
Publisher Licence URL
https://creativecommons.org/licenses/by/4.0/
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