The antiarrhythmic compound efsevin directly modulates voltage-dependent anion channel 2 by binding to its inner wall and enhancing mitochondrial Ca 2+ uptake

Br J Pharmacol. 2020 Jul;177(13):2947-2958. doi: 10.1111/bph.15022. Epub 2020 Mar 25.

Abstract

Background and purpose: The synthetic compound efsevin was recently identified to suppress arrhythmogenesis in models of cardiac arrhythmia, making it a promising candidate for antiarrhythmic therapy. Its activity was shown to be dependent on the voltage-dependent anion channel 2 (VDAC2) in the outer mitochondrial membrane. Here, we investigated the molecular mechanism of the efsevin-VDAC2 interaction.

Experimental approach: To evaluate the functional interaction of efsevin and VDAC2, we measured currents through recombinant VDAC2 in planar lipid bilayers. Using molecular ligand-protein docking and mutational analysis, we identified the efsevin binding site on VDAC2. Finally, physiological consequences of the efsevin-induced modulation of VDAC2 were analysed in HL-1 cardiomyocytes.

Key results: In lipid bilayers, efsevin reduced VDAC2 conductance and shifted the channel's open probability towards less anion-selective closed states. Efsevin binds to a binding pocket formed by the inner channel wall and the pore-lining N-terminal α-helix. Exchange of amino acids N207, K236 and N238 within this pocket for alanines abolished the channel's efsevin-responsiveness. Upon heterologous expression in HL-1 cardiomyocytes, both channels, wild-type VDAC2 and the efsevin-insensitive VDAC2AAA restored mitochondrial Ca2+ uptake, but only wild-type VDAC2 was sensitive to efsevin.

Conclusion and implications: In summary, our data indicate a direct interaction of efsevin with VDAC2 inside the channel pore that leads to modified gating and results in enhanced SR-mitochondria Ca2+ transfer. This study sheds new light on the function of VDAC2 and provides a basis for structure-aided chemical optimization of efsevin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Calcium / metabolism*
  • Mitochondria* / metabolism
  • Mitochondrial Membranes / metabolism
  • Myocytes, Cardiac / metabolism
  • Voltage-Dependent Anion Channel 2* / agonists
  • Voltage-Dependent Anion Channel 2* / metabolism
  • Zebrafish
  • Zebrafish Proteins

Substances

  • Voltage-Dependent Anion Channel 2
  • Zebrafish Proteins
  • Calcium