Biology subjects

Denton, J. S.

Publications and source records attributed to Denton, J. S..

2 recordsLinked to original sources

bioRxiv2025

A conserved mechanism of LRRC8 channel inhibition by distinct drugs

We employed a Leucine Rich Repeat Containing 8 (LRRC8) channel chimera, termed 8C-8A(IL125), to investigate the molecular mechanism of action of the novel volume-sensitive anion channel (VRAC) inhibitor, zafirlukast. 8C-8A(IL125) comprises LRRC8C (8C) and 25 residues from LRRC8A (8A) intracellular loop 1 (IL1) and forms volume-sensitive, structurally defined heptameric channels with normal pharmacological properties. In silico docking and modeling with AlphaFold3 identified a putative zafirlukast binding site comprising the amino (N)-terminal domain (NTD) and inter-subunit fenestrae between transmembrane (TM) helices 1 and 2. Consistent with this model, mutations in NTD, TM1, and TM2 alter 8C-8A(IL125) and heteromeric 8A/8C sensitivity to zafirlukast and the structurally distinct drug pranlukast. Inhibition is not mediated by extracellular pore block or the so-called lipid gate. Mutations or low pH conditions that enhance voltage-dependent inactivation also increase zafirlukast sensitivity. We propose zafirlukast and pranlukast promote channel inactivation through destabilization of the pore.

pharmacology and toxicology↗

bioRxiv2022

Structure of a LRRC8 chimera with physiologically relevant properties reveals heptameric assembly and pore-blocking lipids

Volume-regulated anion channels (VRACs) mediate Cl- and organic solute efflux from vertebrate cells and are essential for cell volume homeostasis. VRACs are heteromeric assemblies of LRRC8A-E proteins with unknown stoichiometries. Homomeric LRRC8A and LRRC8D channels have a hexameric structure. However, these channels are either non-functional or exhibit abnormal functional properties limiting their utility for structure-function analyses. We circumvented these limitations by developing novel homomeric LRRC8 chimeric channels with physiologically relevant functional properties. We demonstrate here that the LRRC8C-LRRC8A(IL125) chimera comprising LRRC8C and 25 amino acids unique to the first intracellular loop (IL1) of LRRC8A has a heptameric structure like that of homologous pannexin channels. Membrane lipids are a key structural element of the channel and are located between subunits and occluding the channel pore. Our results suggest that native VRAC/LRRC8 channels are heptamers and that associated lipids are likely essential for normal channel gating and regulation.

biophysics↗