Affinage

LRRC8E

Volume-regulated anion channel subunit LRRC8E · UniProt Q6NSJ5

Length
796 aa
Mass
90.2 kDa
Annotated
2026-04-28
20 papers in source corpus 11 papers cited in narrative 11 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

LRRC8E is a subunit of the volume-regulated anion channel (VRAC), forming heteromeric complexes with the obligate subunit LRRC8A to create channels with distinct substrate selectivity, gating properties, and tissue-specific expression. LRRC8A/E-containing channels preferentially transport cGAMP and other cyclic dinucleotides across the plasma membrane, and in primary astrocytes they favor permeation of charged osmolytes such as d-aspartate over uncharged solutes (PMID:32277911, PMID:33171122, PMID:28833202). The first extracellular loop of LRRC8E contributes to outer pore formation and determines inactivation kinetics and ion selectivity, while two intracellular cysteines (C424/C448) in the leucine-rich repeat domain form a disulfide bond upon oxidation that uniquely potentiates channel activity more than 10-fold (PMID:27325695, PMID:35861288, PMID:28841766). Lrrc8e-knockout mice show impaired cGAMP-dependent interferon responses and compromised anti-HSV-1 immunity, yet LRRC8E is dispensable for T/B cell development and cGAMP-mediated antitumor immunity in vivo (PMID:32277911, PMID:41419196).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2015 High

    Demonstrating that individual LRRC8 subunits confer distinct substrate selectivities established that LRRC8E-containing VRACs are not involved in cisplatin uptake, unlike LRRC8D-containing channels, introducing the principle of subunit-dependent cargo specificity.

    Evidence Genetic ablation of individual LRRC8 subunits with drug uptake and viability assays in cell lines

    PMID:26530471

    Open questions at the time
    • Positive substrates of LRRC8E-containing channels not yet identified
    • Stoichiometry of heteromeric LRRC8A/E channels unknown
  2. 2016 High

    Structure-function dissection of the first extracellular loop revealed that LRRC8E's EL1 is a major determinant of channel inactivation kinetics, voltage dependence, and anion selectivity, establishing this region as a pore-forming element.

    Evidence LRRC8C/E chimeras and charge-reversal point mutations combined with patch-clamp electrophysiology

    PMID:27325695

    Open questions at the time
    • Atomic-resolution structure of LRRC8A/E heteromer not determined
    • Contribution of other extracellular loops to pore properties unknown
  3. 2017 High

    Two concurrent findings established that LRRC8E-containing channels (a) preferentially conduct charged osmolytes in astrocytes and (b) are uniquely and dramatically potentiated by oxidation, in contrast to the inhibition seen with LRRC8A/C and LRRC8A/D heteromers, revealing subunit-specific redox regulation.

    Evidence RNAi with radiotracer efflux assays in rat astrocytes; chloramine-T and tBHP oxidation with patch-clamp in HEK293 and Jurkat cells

    PMID:28833202 PMID:28841766

    Open questions at the time
    • Physiological oxidant source activating LRRC8E in vivo unidentified
    • Molecular basis of oxidation-dependent activation not yet mapped to specific residues
  4. 2018 High

    Systematic domain-swap analysis confirmed that the EL1 of LRRC8E is essential for VRAC activity and showed that LRRC8A's intracellular loop, not LRRC8E's, governs volume-dependent regulation, delineating domain-level contributions of each subunit.

    Evidence Domain-swap chimeras between LRRC8 paralogs with swelling-activated current recordings and anion permeability measurements

    PMID:29853476

    Open questions at the time
    • How volume sensing is transduced through LRRC8A's intracellular loop to LRRC8E-containing heteromers remains unknown
  5. 2020 High

    Two independent studies identified cGAMP and cyclic dinucleotides as key substrates of LRRC8A/E channels and showed that Lrrc8e-knockout mice have impaired interferon responses and compromised anti-HSV-1 immunity, establishing a direct in vivo role for LRRC8E in innate immune signaling.

    Evidence CRISPR screens, Co-IP, electrophysiology, VRAC reconstitution, Lrrc8e-/- mice with viral challenge

    PMID:32277911 PMID:33171122

    Open questions at the time
    • Relative contribution of LRRC8C versus LRRC8E to cGAMP transport in different tissues not resolved
    • Whether LRRC8E mediates cGAMP import, export, or both in physiological settings unclear
  6. 2021 Medium

    Identification of tonic VRAC activation by a serum protein component requiring plasma-membrane-localized cGAS (independent of its enzymatic activity) revealed an unexpected non-canonical mode of LRRC8A/E channel regulation.

    Evidence Serum depletion/repletion, proteinase K treatment, cGAS-KO cells, PIP2 manipulation

    PMID:33827893

    Open questions at the time
    • Identity of the serum factor unknown
    • Mechanism linking membrane cGAS to channel opening not defined
    • Not independently replicated
  7. 2022 High

    Two studies resolved (a) the specific cysteines (C424/C448) in LRRC8E's LRR domain that form a disulfide bond to activate the channel upon oxidation, providing a molecular mechanism for redox sensitivity, and (b) the in vivo tissue distribution of LRRC8E to renal intercalated cells.

    Evidence Cysteine mutagenesis with concatemeric/chimeric constructs and electrophysiology; epitope-tagged knock-in mice with immunohistochemistry

    PMID:35777784 PMID:35861288

    Open questions at the time
    • Physiological role of LRRC8E in intercalated cell function unknown
    • Whether the C424-C448 disulfide forms under physiological oxidative stress in vivo not shown
    • Structural basis of how disulfide formation opens the pore not resolved
  8. 2025 Medium

    Demonstrating that LRRC8E knockout has no effect on T/B cell development or cGAMP-dependent antitumor immunity in vivo narrowed the physiological scope of LRRC8E's immune function, indicating compensatory or alternative cGAMP transport pathways in these contexts.

    Evidence LRRC8 subunit-specific KO mice, syngeneic tumor models (MC38, B16-F10), serum cytokine and tumor growth assays

    PMID:41419196

    Open questions at the time
    • Compensatory pathways for cGAMP transport in immune cells not identified
    • Whether LRRC8E has non-immune physiological roles (e.g., in kidney) remains untested
    • Single study

Open questions

Synthesis pass · forward-looking unresolved questions
  • A high-resolution structure of the LRRC8A/E heteromeric channel and the identification of LRRC8E's physiological role in renal intercalated cells remain key open questions.
  • No cryo-EM or crystal structure of LRRC8A/E heteromer
  • Functional consequence of LRRC8E expression in intercalated cells unknown
  • In vivo relevance of oxidation-dependent activation not established

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 4
Localization
GO:0005886 plasma membrane 3
Pathway
R-HSA-168256 Immune System 3
Partners
LRRC8ALRRC8C
Complex memberships
VRAC (LRRC8 volume-regulated anion channel)

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2020 LRRC8A/LRRC8E-containing VRACs transport cGAMP and cyclic dinucleotides across the plasma membrane; Lrrc8e-/- mice exhibited impaired IFN responses and compromised immunity to HSV-1, establishing a direct role for LRRC8E in cGAMP-mediated anti-viral immunity via VRAC-dependent transport. Biochemical and electrophysiological analyses, genetic ablation (Lrrc8e-/- mice), VRAC reconstitution, chemical blockade Immunity High 32277911
2020 LRRC8A forms complexes with LRRC8C and/or LRRC8E to transport cGAMP and other 2'3'-cyclic dinucleotides; in contrast, LRRC8D inhibits cGAMP transport. cGAMP efflux or influx via LRRC8 channels is dictated by the cGAMP electrochemical gradient. Genome-wide CRISPR screen, Co-IP, electrophysiology, genetic KD/KO with defined transport assays Molecular cell High 33171122
2015 LRRC8E-containing VRACs do not contribute significantly to cisplatin uptake under isotonic conditions (unlike LRRC8D-containing VRACs), establishing subunit-dependent substrate specificity within the LRRC8 heteromeric channel complex. Genetic ablation of individual LRRC8 subunits, drug uptake assays, cell viability assays The EMBO journal High 26530471
2017 In primary rat astrocytes, LRRC8A/C/E-containing VRACs form a conduit preferentially for charged osmolytes (d-aspartate), while LRRC8A/D channels dominate release of uncharged osmolytes (taurine, myo-inositol), demonstrating subunit-dependent substrate selectivity for LRRC8E-containing channels. RNAi knockdown of individual LRRC8 subunits, radiotracer efflux assays under hypoosmotic challenge The Journal of physiology Medium 28833202
2016 The C-terminal part of the first extracellular loop (EL1) of LRRC8 subunits, including LRRC8E, is a major determinant of ICl,vol inactivation kinetics and voltage dependence, and also influences iodide/chloride permeability, suggesting participation in outer pore formation. Chimeric channel construction (LRRC8C/LRRC8E), point mutations (charge reversal at conserved residues), electrophysiology The Journal of biological chemistry High 27325695
2017 LRRC8A/LRRC8E heteromeric channels are dramatically activated (>10-fold) by oxidation of intracellular cysteine residues, whereas LRRC8A/LRRC8C and LRRC8A/LRRC8D heteromers are inhibited by oxidation, demonstrating that LRRC8 proteins are directly and subunit-dependently modulated by reactive oxygen species. Fluorescently tagged LRRC8 proteins, chloramine-T and tert-butyl hydroperoxide oxidation, patch-clamp electrophysiology in HEK293 and Jurkat cells The Journal of physiology High 28841766
2022 Two intracellular cysteines in the leucine-rich repeat domain of LRRC8E (C424 and C448) form a disulfide bond upon oxidation, causing a conformational change that activates LRRC8A/LRRC8E channels; this was identified using chimeric and concatemeric channel strategies. Chimeric channel construction, concatemeric constructs, cysteine mutagenesis, patch-clamp electrophysiology The Journal of physiology High 35861288
2018 The first extracellular loop (EL1) of LRRC8E (as well as LRRC8C and LRRC8D) is essential for VRAC activity; the intracellular loop (IL) of LRRC8A, but not of LRRC8E, governs normal volume-dependent regulation and influences pore structure (anion permeability, rectification, voltage sensitivity). Domain-swap chimeras between LRRC8 paralogs, swelling-activated current recordings, anion permeability measurements The Journal of general physiology High 29853476
2021 LRRC8A/LRRC8E-containing VRACs can be tonically opened by a protein component in serum under resting conditions; this activation requires cGAS localized at the plasma membrane (not its enzymatic activity) and is facilitated by PIP2-dependent membrane association of cGAS. Serum depletion/repletion experiments, proteinase K treatment, genetic analyses (cGAS KO), cGAS membrane localization studies, PIP2 manipulation Journal of immunology Medium 33827893
2022 In the kidney, LRRC8E is specifically localized to intercalated cells of the nephron, a distinct localization from other LRRC8 subunits (LRRC8A/B/D in proximal tubule basolateral membranes; LRRC8C in vascular endothelium), established using epitope-tagged knock-in mice. Knock-in mice expressing epitope-tagged LRRC8 subunits, immunohistochemistry/localization, constitutive subunit-specific KO mice Journal of the American Society of Nephrology Medium 35777784
2025 Disruption of LRRC8E (individually or with other non-essential subunits LRRC8B-D) had no discernible effect on T or B cell development in mice; furthermore, VRAC-mediated cGAMP transport is dispensable for the cGAMP-mediated antitumor immune response in vivo in syngeneic mouse tumor models. LRRC8 subunit-specific KO mice, syngeneic tumor models (MC38, B16-F10), serum cytokine measurements, tumor growth assays The Journal of biological chemistry Medium 41419196

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2020 Transfer of cGAMP into Bystander Cells via LRRC8 Volume-Regulated Anion Channels Augments STING-Mediated Interferon Responses and Anti-viral Immunity. Immunity 240 32277911
2015 Subunit composition of VRAC channels determines substrate specificity and cellular resistance to Pt-based anti-cancer drugs. The EMBO journal 222 26530471
2020 LRRC8A:C/E Heteromeric Channels Are Ubiquitous Transporters of cGAMP. Molecular cell 150 33171122
2017 Molecular composition and heterogeneity of the LRRC8-containing swelling-activated osmolyte channels in primary rat astrocytes. The Journal of physiology 83 28833202
2016 Inactivation and Anion Selectivity of Volume-regulated Anion Channels (VRACs) Depend on C-terminal Residues of the First Extracellular Loop. The Journal of biological chemistry 50 27325695
2017 Subunit-dependent oxidative stress sensitivity of LRRC8 volume-regulated anion channels. The Journal of physiology 48 28841766
2004 LRRC8 involved in B cell development belongs to a novel family of leucine-rich repeat proteins. FEBS letters 47 15094057
2019 LINC00958 facilitates cervical cancer cell proliferation and metastasis by sponging miR-625-5p to upregulate LRRC8E expression. Journal of cellular biochemistry 43 31691355
2018 Intracellular and extracellular loops of LRRC8 are essential for volume-regulated anion channel function. The Journal of general physiology 38 29853476
2016 Specific and essential but not sufficient roles of LRRC8A in the activity of volume-sensitive outwardly rectifying anion channel (VSOR). Channels (Austin, Tex.) 33 27764579
2017 Leucine-rich repeat-containing 8B protein is associated with the endoplasmic reticulum Ca2+ leak in HEK293 cells. Journal of cell science 24 28972132
2022 Renal Deletion of LRRC8/VRAC Channels Induces Proximal Tubulopathy. Journal of the American Society of Nephrology : JASN 20 35777784
2022 Molecular determinants underlying volume-regulated anion channel subunit-dependent oxidation sensitivity. The Journal of physiology 18 35861288
2021 Regulation of Anion Channel LRRC8 Volume-Regulated Anion Channels in Transport of 2'3'-Cyclic GMP-AMP and Cisplatin under Steady State and Inflammation. Journal of immunology (Baltimore, Md. : 1950) 18 33827893
2014 A simple method for estimating the strength of natural selection on overlapping genes. Genome biology and evolution 16 25552532
2022 LncRNA PCAT6 activated by SP1 facilitates the progression of breast cancer by the miR-326/LRRC8E axis. Anti-cancer drugs 8 34620745
2022 Knockdown of LINC00511 decreased cisplatin resistance in non-small cell lung cancer by elevating miR-625 level to suppress the expression of leucine rich repeat containing eight volume-regulated anion channel subunit E. Human & experimental toxicology 7 35363093
2016 Association between genes on chromosome 19p13.2 and panic disorder. Psychiatric genetics 7 27610895
2024 Unveiling the therapeutic potential: KBU2046 halts triple-negative breast cancer cell migration by constricting TGF-β1 activation in vitro. Oncology research 1 39449805
2025 A protective cGAMP-mediated anti-tumor immune response can proceed without LRRC8/VRAC channels. The Journal of biological chemistry 0 41419196