title: LRRC8 Proteins Form Volume-Regulated Anion Channels that Sense Ionic Strength.
abstract: The volume-regulated anion channel (VRAC) is activated when a cell swells, and it plays a central role in maintaining cell volume in response to osmotic challenges. SWELL1 (LRRC8A) was recently identified as an essential component of VRAC. However, the identity of the pore-forming subunits of VRAC and how the channel is gated by cell swelling are unknown. Here, we show that SWELL1 and up to four other LRRC8 subunits assemble into heterogeneous complexes of ∼800 kDa. When reconstituted into bilayers, LRRC8 complexes are sufficient to form anion channels activated by osmolality gradients. In bilayers, as well as in cells, the single-channel conductance of the complexes depends on the LRRC8 composition. Finally, low ionic strength (Γ) in the absence of an osmotic gradient activates the complexes in bilayers. These data demonstrate that LRRC8 proteins together constitute the VRAC pore and that hypotonic stress can activate VRAC through a decrease in cytoplasmic Γ.
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Ruhma
authors.initials: R
authors.lastname: Syeda
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA; Genomics Institute of the Novartis Research Foundation (GNF), San Diego, CA 92121, USA.
authors.forename: Zhaozhu
authors.initials: Z
authors.lastname: Qiu
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA. Electronic address: adubin@scripps.edu.
authors.forename: Adrienne E
authors.initials: AE
authors.lastname: Dubin
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Swetha E
authors.initials: SE
authors.lastname: Murthy
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Maria N
authors.initials: MN
authors.lastname: Florendo
authors.affiliation: Genomics Institute of the Novartis Research Foundation (GNF), San Diego, CA 92121, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Mason
authors.affiliation: Genomics Institute of the Novartis Research Foundation (GNF), San Diego, CA 92121, USA.
authors.forename: Jayanti
authors.initials: J
authors.lastname: Mathur
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Cahalan
authors.affiliation: Genomics Institute of the Novartis Research Foundation (GNF), San Diego, CA 92121, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Peters
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Montal
authors.affiliation: Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA. Electronic address: ardem@scripps.edu.
authors.forename: Ardem
authors.initials: A
authors.lastname: Patapoutian
mesh_terms: D006367:HeLa Cells; D006801:Humans; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D009995:Osmosis
chemical_list: D007473:Ion Channels; C485976:LRRC8A protein, human; D008051:Lipid Bilayers; D008565:Membrane Proteins; D046912:Multiprotein Complexes
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