Publication

Back to overview Show all

Original article (peer-reviewed)

Journal Frontiers in Physiology
Volume (Issue) 11
Page(s) 589386
Title of proceedings Frontiers in Physiology
DOI 10.3389/fphys.2020.589386

Open Access

URL http://doi.org/10.3389/fphys.2020.589386
Type of Open Access Publisher (Gold Open Access)

Abstract

Background: Nav1.5 cardiac NaC channel mutations can cause arrhythmogenic syndromes. Some of these mutations exert a dominant negative effect on wild-type channels. Recent studies showed that NaC channels can dimerize, allowing coupled gating. This leads to the hypothesis that allosteric interactions between NaC channels modulate their function and that these interactions may contribute to the negative dominance of certain mutations. Methods: To investigate how allosteric interactions affect microscopic and macroscopic channel function, we developed a modeling paradigm in which Markovian models of two channels are combined. Allosteric interactions are incorporated by modifying the free energies of the composite states and/or barriers between states. Results: Simulations using two generic 2-state models (C-O, closed-open) revealed that increasing the free energy of the composite states CO/OC leads to coupled gating. Simulations using two 3-state models (closed-open-inactivated) revealed that coupled closings must also involve interactions between further composite states. Using two 6-state cardiac NaC channel models, we replicated previous experimental results mainly by increasing the energies of the CO/OC states and lowering the energy barriers between the CO/OC and the CO/OO states. The channel model was then modified to simulate a negative dominant mutation (Nav1.5 p.L325R). Simulations of homodimers and heterodimers in the presence and absence of interactions showed that the interactions with the variant channel impair the opening of the wild-type channel and thus contribute to negative dominance. Conclusion: Our new modeling framework recapitulates qualitatively previous experimental observations and helps identifying possible interaction mechanisms between ion channels.
-