A Membrane-Disruptive Action of VBIT-4 Challenges Its Role as a Widely Used VDAC1 Oligomerization Inhibitor
Abstract
Voltage-dependent anion channel (VDAC) is the most abundant protein of the mitochondrial outer membrane and a key regulator of metabolite exchange and mitochondrial physiology. Its oligomerization has been proposed to control processes such as mitochondrial DNA release and membrane remodeling, yet the underlying mechanisms remain poorly defined. VBIT-4 has been widely used over the last decade as a putative inhibitor of VDAC1 oligomerization, despite limited mechanistic validation. Here, using high-speed atomic force microscopy (AFM), we directly visualized VDAC1 assemblies in lipid membranes and examined the effect of VBIT-4. Unexpectedly, VBIT-4 induced membrane defects and permeabilization at micromolar concentrations, independently of VDAC1. Quantitative AFM analysis further shows that VBIT-4 does not alter VDAC1 cluster organization. Complementary electrophysiology, microscale thermophoresis, and coarse-grained molecular dynamics demonstrate that VBIT-4 partitions into lipid bilayers, increases membrane permeability, and destabilizes membrane structure, without detectable effects on VDAC1 channel properties or assemblies. Consistent with this mechanism, VBIT-4 induces VDAC1-independent cytotoxicity in HeLa cells at concentrations above 10 µM. Together, these results demonstrate that VBIT-4 does not act as a specific inhibitor of VDAC1 oligomerization but instead functions as a membrane-active compound. This work provides a revised framework for interpreting studies using VBIT-4 and highlights the importance of systematically assessing drug–membrane interactions when targeting membrane proteins.
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BibTeX
@article{ravishankar2026membranedisruptive,
title = {{A Membrane-Disruptive Action of VBIT-4 Challenges Its Role as a Widely Used VDAC1 Oligomerization Inhibitor}},
author = {Varun Ravishankar and Luís Borges-Araújo and Megha Rajendran and Elodie Lafargue and Deborah Byrne and Nicolas Buzhinsky and Mya Wolfe and Wendy Fitzgerald and Nina Bautista and Bethel Beyene and Motahareh Larimi and Jean-Pierre Duneau and James Sturgis and Sergey Bezrukov and Ignacio Casuso and Tatiana Rostovtseva and Lucie Bergdoll},
journal = {eLife},
year = {2026},
month = sep,
doi = {10.7554/elife.111980.2},
url = {https://amu.hal.science/hal-05738253v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Membrane-Disruptive Action of VBIT-4 Challenges Its Role as a Widely Used VDAC1 Oligomerization Inhibitor
AU - Varun Ravishankar
AU - Luís Borges-Araújo
AU - Megha Rajendran
AU - Elodie Lafargue
AU - Deborah Byrne
AU - Nicolas Buzhinsky
AU - Mya Wolfe
AU - Wendy Fitzgerald
AU - Nina Bautista
AU - Bethel Beyene
AU - Motahareh Larimi
AU - Jean-Pierre Duneau
AU - James Sturgis
AU - Sergey Bezrukov
AU - Ignacio Casuso
AU - Tatiana Rostovtseva
AU - Lucie Bergdoll
PY - 2026
DA - 2026/09/03
JO - eLife
DO - 10.7554/elife.111980.2
UR - https://amu.hal.science/hal-05738253v1
AB - Voltage-dependent anion channel (VDAC) is the most abundant protein of the mitochondrial outer membrane and a key regulator of metabolite exchange and mitochondrial physiology. Its oligomerization has been proposed to control processes such as mitochondrial DNA release and membrane remodeling, yet the underlying mechanisms remain poorly defined. VBIT-4 has been widely used over the last decade as a putative inhibitor of VDAC1 oligomerization, despite limited mechanistic validation. Here, using high-speed atomic force microscopy (AFM), we directly visualized VDAC1 assemblies in lipid membranes and examined the effect of VBIT-4. Unexpectedly, VBIT-4 induced membrane defects and permeabilization at micromolar concentrations, independently of VDAC1. Quantitative AFM analysis further shows that VBIT-4 does not alter VDAC1 cluster organization. Complementary electrophysiology, microscale thermophoresis, and coarse-grained molecular dynamics demonstrate that VBIT-4 partitions into lipid bilayers, increases membrane permeability, and destabilizes membrane structure, without detectable effects on VDAC1 channel properties or assemblies. Consistent with this mechanism, VBIT-4 induces VDAC1-independent cytotoxicity in HeLa cells at concentrations above 10 µM. Together, these results demonstrate that VBIT-4 does not act as a specific inhibitor of VDAC1 oligomerization but instead functions as a membrane-active compound. This work provides a revised framework for interpreting studies using VBIT-4 and highlights the importance of systematically assessing drug–membrane interactions when targeting membrane proteins.
SN - 2050-084X
ER -