{"gene":"LRRC8E","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2020,"finding":"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.","method":"Biochemical and electrophysiological analyses, genetic ablation (Lrrc8e-/- mice), VRAC reconstitution, chemical blockade","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 1–2 — electrophysiology, genetic KO mice with defined immune phenotype, replicated across multiple experimental approaches","pmids":["32277911"],"is_preprint":false},{"year":2020,"finding":"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.","method":"Genome-wide CRISPR screen, Co-IP, electrophysiology, genetic KD/KO with defined transport assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (CRISPR screen, transport assays, electrophysiology), independent from PMID 32277911","pmids":["33171122"],"is_preprint":false},{"year":2015,"finding":"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.","method":"Genetic ablation of individual LRRC8 subunits, drug uptake assays, cell viability assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — clean genetic KO with specific quantitative uptake phenotype, multiple subunits compared","pmids":["26530471"],"is_preprint":false},{"year":2017,"finding":"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.","method":"RNAi knockdown of individual LRRC8 subunits, radiotracer efflux assays under hypoosmotic challenge","journal":"The Journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 — clean RNAi with quantitative radiotracer readout, but single lab","pmids":["28833202"],"is_preprint":false},{"year":2016,"finding":"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.","method":"Chimeric channel construction (LRRC8C/LRRC8E), point mutations (charge reversal at conserved residues), electrophysiology","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — structure-function mutagenesis with electrophysiological readout, chimera and point-mutation strategies orthogonally confirming role of EL1","pmids":["27325695"],"is_preprint":false},{"year":2017,"finding":"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.","method":"Fluorescently tagged LRRC8 proteins, chloramine-T and tert-butyl hydroperoxide oxidation, patch-clamp electrophysiology in HEK293 and Jurkat cells","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1–2 — direct electrophysiology on defined heteromers, multiple oxidants, replicated across cell types","pmids":["28841766"],"is_preprint":false},{"year":2022,"finding":"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.","method":"Chimeric channel construction, concatemeric constructs, cysteine mutagenesis, patch-clamp electrophysiology","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis combined with electrophysiology and chimeric channel strategies, identifying specific molecular residues","pmids":["35861288"],"is_preprint":false},{"year":2018,"finding":"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).","method":"Domain-swap chimeras between LRRC8 paralogs, swelling-activated current recordings, anion permeability measurements","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 — systematic chimeric channel analysis with multiple electrophysiological readouts","pmids":["29853476"],"is_preprint":false},{"year":2021,"finding":"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.","method":"Serum depletion/repletion experiments, proteinase K treatment, genetic analyses (cGAS KO), cGAS membrane localization studies, PIP2 manipulation","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic and biochemical dissection of activation mechanism, but single lab","pmids":["33827893"],"is_preprint":false},{"year":2022,"finding":"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.","method":"Knock-in mice expressing epitope-tagged LRRC8 subunits, immunohistochemistry/localization, constitutive subunit-specific KO mice","journal":"Journal of the American Society of Nephrology","confidence":"Medium","confidence_rationale":"Tier 2 — direct in vivo localization with tagged protein in knock-in mice, but functional role of LRRC8E-specific intercalated cell expression not fully resolved","pmids":["35777784"],"is_preprint":false},{"year":2025,"finding":"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.","method":"LRRC8 subunit-specific KO mice, syngeneic tumor models (MC38, B16-F10), serum cytokine measurements, tumor growth assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — clean in vivo genetic KO with defined immune and tumor phenotype, but single study","pmids":["41419196"],"is_preprint":false}],"current_model":"LRRC8E functions as a non-essential but functionally specialized subunit of the heteromeric volume-regulated anion channel (VRAC), forming complexes with obligate subunit LRRC8A to create channels with distinct substrate selectivity — particularly for cGAMP/cyclic dinucleotide transport and charged osmolyte permeation — whose gating is uniquely potentiated by oxidation of two intracellular cysteines (C424/C448) in the LRR domain that form a disulfide bond, and whose pore properties and inactivation kinetics are determined by its first extracellular loop; LRRC8E-containing VRACs are specifically localized to renal intercalated cells in vivo, and while LRRC8A/E channels contribute to cGAMP-mediated innate immune signaling, LRRC8E is dispensable for T/B cell development and the antitumor immune response in vivo."},"narrative":{"teleology":[{"year":2015,"claim":"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","pmids":["26530471"],"confidence":"High","gaps":["Positive substrates of LRRC8E-containing channels not yet identified","Stoichiometry of heteromeric LRRC8A/E channels unknown"]},{"year":2016,"claim":"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","pmids":["27325695"],"confidence":"High","gaps":["Atomic-resolution structure of LRRC8A/E heteromer not determined","Contribution of other extracellular loops to pore properties unknown"]},{"year":2017,"claim":"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","pmids":["28833202","28841766"],"confidence":"High","gaps":["Physiological oxidant source activating LRRC8E in vivo unidentified","Molecular basis of oxidation-dependent activation not yet mapped to specific residues"]},{"year":2018,"claim":"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","pmids":["29853476"],"confidence":"High","gaps":["How volume sensing is transduced through LRRC8A's intracellular loop to LRRC8E-containing heteromers remains unknown"]},{"year":2020,"claim":"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","pmids":["32277911","33171122"],"confidence":"High","gaps":["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"]},{"year":2021,"claim":"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","pmids":["33827893"],"confidence":"Medium","gaps":["Identity of the serum factor unknown","Mechanism linking membrane cGAS to channel opening not defined","Not independently replicated"]},{"year":2022,"claim":"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","pmids":["35861288","35777784"],"confidence":"High","gaps":["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"]},{"year":2025,"claim":"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","pmids":["41419196"],"confidence":"Medium","gaps":["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"]},{"year":null,"claim":"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.","evidence":"","pmids":[],"confidence":"Low","gaps":["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":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,3,4]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,8,9]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,1,10]}],"complexes":["VRAC (LRRC8 volume-regulated anion channel)"],"partners":["LRRC8A","LRRC8C"],"other_free_text":[]},"mechanistic_narrative":"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]."},"prefetch_data":{"uniprot":{"accession":"Q6NSJ5","full_name":"Volume-regulated anion channel subunit LRRC8E","aliases":["Leucine-rich repeat-containing protein 8E"],"length_aa":796,"mass_kda":90.2,"function":"Non-essential component of the volume-regulated anion channel (VRAC, also named VSOAC channel), an anion channel required to maintain a constant cell volume in response to extracellular or intracellular osmotic changes (PubMed:24790029, PubMed:26824658, PubMed:28193731). The VRAC channel conducts iodide better than chloride and can also conduct organic osmolytes like taurine (PubMed:24790029, PubMed:26824658). Mediates efflux of amino acids, such as aspartate, in response to osmotic stress (PubMed:28193731). The VRAC channel also mediates transport of immunoreactive cyclic dinucleotide GMP-AMP (2'-3'-cGAMP), an immune messenger produced in response to DNA virus in the cytosol (PubMed:33171122). Channel activity requires LRRC8A plus at least one other family member (LRRC8B, LRRC8C, LRRC8D or LRRC8E); channel characteristics depend on the precise subunit composition (PubMed:24790029, PubMed:26824658, PubMed:28193731). Also plays a role in lysosome homeostasis by forming functional lysosomal VRAC channels in response to low cytoplasmic ionic strength condition: lysosomal VRAC channels are necessary for the formation of large lysosome-derived vacuoles, which store and then expel excess water to maintain cytosolic water homeostasis (PubMed:33139539)","subcellular_location":"Cell membrane; Endoplasmic reticulum membrane; Lysosome membrane; Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q6NSJ5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LRRC8E","classification":"Not Classified","n_dependent_lines":16,"n_total_lines":1208,"dependency_fraction":0.013245033112582781},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CANX","stoichiometry":0.2},{"gene":"CCDC47","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LRRC8E","total_profiled":1310},"omim":[{"mim_id":"612891","title":"LEUCINE-RICH REPEAT-CONTAINING PROTEIN 8E; LRRC8E","url":"https://www.omim.org/entry/612891"},{"mim_id":"608360","title":"LEUCINE-RICH REPEAT-CONTAINING PROTEIN 8A; LRRC8A","url":"https://www.omim.org/entry/608360"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LRRC8E"},"hgnc":{"alias_symbol":["FLJ23420"],"prev_symbol":[]},"alphafold":{"accession":"Q6NSJ5","domains":[{"cath_id":"1.20.1440","chopping":"17-58_95-142_254-362","consensus_level":"high","plddt":89.3396,"start":17,"end":362},{"cath_id":"3.80.10.10","chopping":"618-796","consensus_level":"medium","plddt":93.3278,"start":618,"end":796}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6NSJ5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6NSJ5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6NSJ5-F1-predicted_aligned_error_v6.png","plddt_mean":84.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LRRC8E","jax_strain_url":"https://www.jax.org/strain/search?query=LRRC8E"},"sequence":{"accession":"Q6NSJ5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6NSJ5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6NSJ5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6NSJ5"}},"corpus_meta":[{"pmid":"32277911","id":"PMC_32277911","title":"Transfer of cGAMP into Bystander Cells via LRRC8 Volume-Regulated Anion Channels Augments STING-Mediated Interferon Responses and Anti-viral Immunity.","date":"2020","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/32277911","citation_count":240,"is_preprint":false},{"pmid":"26530471","id":"PMC_26530471","title":"Subunit composition of VRAC channels determines substrate specificity and cellular resistance to Pt-based anti-cancer drugs.","date":"2015","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/26530471","citation_count":222,"is_preprint":false},{"pmid":"33171122","id":"PMC_33171122","title":"LRRC8A:C/E Heteromeric Channels Are Ubiquitous Transporters of cGAMP.","date":"2020","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/33171122","citation_count":150,"is_preprint":false},{"pmid":"28833202","id":"PMC_28833202","title":"Molecular composition and heterogeneity of the LRRC8-containing swelling-activated osmolyte channels in primary rat astrocytes.","date":"2017","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/28833202","citation_count":83,"is_preprint":false},{"pmid":"27325695","id":"PMC_27325695","title":"Inactivation and Anion Selectivity of Volume-regulated Anion Channels (VRACs) Depend on C-terminal Residues of the First Extracellular Loop.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27325695","citation_count":50,"is_preprint":false},{"pmid":"28841766","id":"PMC_28841766","title":"Subunit-dependent oxidative stress sensitivity of LRRC8 volume-regulated anion channels.","date":"2017","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/28841766","citation_count":48,"is_preprint":false},{"pmid":"15094057","id":"PMC_15094057","title":"LRRC8 involved in B cell development belongs to a novel family of leucine-rich repeat proteins.","date":"2004","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/15094057","citation_count":47,"is_preprint":false},{"pmid":"31691355","id":"PMC_31691355","title":"LINC00958 facilitates cervical cancer cell proliferation and metastasis by sponging miR-625-5p to upregulate LRRC8E expression.","date":"2019","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31691355","citation_count":43,"is_preprint":false},{"pmid":"29853476","id":"PMC_29853476","title":"Intracellular and extracellular loops of LRRC8 are essential for volume-regulated anion channel function.","date":"2018","source":"The Journal of general physiology","url":"https://pubmed.ncbi.nlm.nih.gov/29853476","citation_count":38,"is_preprint":false},{"pmid":"27764579","id":"PMC_27764579","title":"Specific and essential but not sufficient roles of LRRC8A in the activity of volume-sensitive outwardly rectifying anion channel (VSOR).","date":"2016","source":"Channels (Austin, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/27764579","citation_count":33,"is_preprint":false},{"pmid":"28972132","id":"PMC_28972132","title":"Leucine-rich repeat-containing 8B protein is associated with the endoplasmic reticulum Ca2+ leak in HEK293 cells.","date":"2017","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/28972132","citation_count":24,"is_preprint":false},{"pmid":"35777784","id":"PMC_35777784","title":"Renal Deletion of LRRC8/VRAC Channels Induces Proximal Tubulopathy.","date":"2022","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/35777784","citation_count":20,"is_preprint":false},{"pmid":"35861288","id":"PMC_35861288","title":"Molecular determinants underlying volume-regulated anion channel subunit-dependent oxidation sensitivity.","date":"2022","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/35861288","citation_count":18,"is_preprint":false},{"pmid":"33827893","id":"PMC_33827893","title":"Regulation of Anion Channel LRRC8 Volume-Regulated Anion Channels in Transport of 2'3'-Cyclic GMP-AMP and Cisplatin under Steady State and Inflammation.","date":"2021","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/33827893","citation_count":18,"is_preprint":false},{"pmid":"25552532","id":"PMC_25552532","title":"A simple method for estimating the strength of natural selection on overlapping genes.","date":"2014","source":"Genome biology and evolution","url":"https://pubmed.ncbi.nlm.nih.gov/25552532","citation_count":16,"is_preprint":false},{"pmid":"34620745","id":"PMC_34620745","title":"LncRNA PCAT6 activated by SP1 facilitates the progression of breast cancer by the miR-326/LRRC8E axis.","date":"2022","source":"Anti-cancer drugs","url":"https://pubmed.ncbi.nlm.nih.gov/34620745","citation_count":8,"is_preprint":false},{"pmid":"27610895","id":"PMC_27610895","title":"Association between genes on chromosome 19p13.2 and panic disorder.","date":"2016","source":"Psychiatric genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27610895","citation_count":7,"is_preprint":false},{"pmid":"35363093","id":"PMC_35363093","title":"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.","date":"2022","source":"Human & experimental toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/35363093","citation_count":7,"is_preprint":false},{"pmid":"39449805","id":"PMC_39449805","title":"Unveiling the therapeutic potential: KBU2046 halts triple-negative breast cancer cell migration by constricting TGF-β1 activation in vitro.","date":"2024","source":"Oncology research","url":"https://pubmed.ncbi.nlm.nih.gov/39449805","citation_count":1,"is_preprint":false},{"pmid":"41419196","id":"PMC_41419196","title":"A protective cGAMP-mediated anti-tumor immune response can proceed without LRRC8/VRAC channels.","date":"2025","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41419196","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12082,"output_tokens":2751,"usd":0.038755},"stage2":{"model":"claude-opus-4-6","input_tokens":6092,"output_tokens":2352,"usd":0.13389},"total_usd":0.172645,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2020,\n      \"finding\": \"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.\",\n      \"method\": \"Biochemical and electrophysiological analyses, genetic ablation (Lrrc8e-/- mice), VRAC reconstitution, chemical blockade\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — electrophysiology, genetic KO mice with defined immune phenotype, replicated across multiple experimental approaches\",\n      \"pmids\": [\"32277911\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"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.\",\n      \"method\": \"Genome-wide CRISPR screen, Co-IP, electrophysiology, genetic KD/KO with defined transport assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (CRISPR screen, transport assays, electrophysiology), independent from PMID 32277911\",\n      \"pmids\": [\"33171122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"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.\",\n      \"method\": \"Genetic ablation of individual LRRC8 subunits, drug uptake assays, cell viability assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic KO with specific quantitative uptake phenotype, multiple subunits compared\",\n      \"pmids\": [\"26530471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"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.\",\n      \"method\": \"RNAi knockdown of individual LRRC8 subunits, radiotracer efflux assays under hypoosmotic challenge\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean RNAi with quantitative radiotracer readout, but single lab\",\n      \"pmids\": [\"28833202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"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.\",\n      \"method\": \"Chimeric channel construction (LRRC8C/LRRC8E), point mutations (charge reversal at conserved residues), electrophysiology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — structure-function mutagenesis with electrophysiological readout, chimera and point-mutation strategies orthogonally confirming role of EL1\",\n      \"pmids\": [\"27325695\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"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.\",\n      \"method\": \"Fluorescently tagged LRRC8 proteins, chloramine-T and tert-butyl hydroperoxide oxidation, patch-clamp electrophysiology in HEK293 and Jurkat cells\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct electrophysiology on defined heteromers, multiple oxidants, replicated across cell types\",\n      \"pmids\": [\"28841766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"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.\",\n      \"method\": \"Chimeric channel construction, concatemeric constructs, cysteine mutagenesis, patch-clamp electrophysiology\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis combined with electrophysiology and chimeric channel strategies, identifying specific molecular residues\",\n      \"pmids\": [\"35861288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"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).\",\n      \"method\": \"Domain-swap chimeras between LRRC8 paralogs, swelling-activated current recordings, anion permeability measurements\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic chimeric channel analysis with multiple electrophysiological readouts\",\n      \"pmids\": [\"29853476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"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.\",\n      \"method\": \"Serum depletion/repletion experiments, proteinase K treatment, genetic analyses (cGAS KO), cGAS membrane localization studies, PIP2 manipulation\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic and biochemical dissection of activation mechanism, but single lab\",\n      \"pmids\": [\"33827893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"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.\",\n      \"method\": \"Knock-in mice expressing epitope-tagged LRRC8 subunits, immunohistochemistry/localization, constitutive subunit-specific KO mice\",\n      \"journal\": \"Journal of the American Society of Nephrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct in vivo localization with tagged protein in knock-in mice, but functional role of LRRC8E-specific intercalated cell expression not fully resolved\",\n      \"pmids\": [\"35777784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"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.\",\n      \"method\": \"LRRC8 subunit-specific KO mice, syngeneic tumor models (MC38, B16-F10), serum cytokine measurements, tumor growth assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean in vivo genetic KO with defined immune and tumor phenotype, but single study\",\n      \"pmids\": [\"41419196\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LRRC8E functions as a non-essential but functionally specialized subunit of the heteromeric volume-regulated anion channel (VRAC), forming complexes with obligate subunit LRRC8A to create channels with distinct substrate selectivity — particularly for cGAMP/cyclic dinucleotide transport and charged osmolyte permeation — whose gating is uniquely potentiated by oxidation of two intracellular cysteines (C424/C448) in the LRR domain that form a disulfide bond, and whose pore properties and inactivation kinetics are determined by its first extracellular loop; LRRC8E-containing VRACs are specifically localized to renal intercalated cells in vivo, and while LRRC8A/E channels contribute to cGAMP-mediated innate immune signaling, LRRC8E is dispensable for T/B cell development and the antitumor immune response in vivo.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"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].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"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.\",\n      \"evidence\": \"Genetic ablation of individual LRRC8 subunits with drug uptake and viability assays in cell lines\",\n      \"pmids\": [\"26530471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Positive substrates of LRRC8E-containing channels not yet identified\", \"Stoichiometry of heteromeric LRRC8A/E channels unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"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.\",\n      \"evidence\": \"LRRC8C/E chimeras and charge-reversal point mutations combined with patch-clamp electrophysiology\",\n      \"pmids\": [\"27325695\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution structure of LRRC8A/E heteromer not determined\", \"Contribution of other extracellular loops to pore properties unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"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.\",\n      \"evidence\": \"RNAi with radiotracer efflux assays in rat astrocytes; chloramine-T and tBHP oxidation with patch-clamp in HEK293 and Jurkat cells\",\n      \"pmids\": [\"28833202\", \"28841766\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological oxidant source activating LRRC8E in vivo unidentified\", \"Molecular basis of oxidation-dependent activation not yet mapped to specific residues\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"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.\",\n      \"evidence\": \"Domain-swap chimeras between LRRC8 paralogs with swelling-activated current recordings and anion permeability measurements\",\n      \"pmids\": [\"29853476\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How volume sensing is transduced through LRRC8A's intracellular loop to LRRC8E-containing heteromers remains unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"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.\",\n      \"evidence\": \"CRISPR screens, Co-IP, electrophysiology, VRAC reconstitution, Lrrc8e-/- mice with viral challenge\",\n      \"pmids\": [\"32277911\", \"33171122\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"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\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"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.\",\n      \"evidence\": \"Serum depletion/repletion, proteinase K treatment, cGAS-KO cells, PIP2 manipulation\",\n      \"pmids\": [\"33827893\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of the serum factor unknown\", \"Mechanism linking membrane cGAS to channel opening not defined\", \"Not independently replicated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"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.\",\n      \"evidence\": \"Cysteine mutagenesis with concatemeric/chimeric constructs and electrophysiology; epitope-tagged knock-in mice with immunohistochemistry\",\n      \"pmids\": [\"35861288\", \"35777784\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"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\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"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.\",\n      \"evidence\": \"LRRC8 subunit-specific KO mice, syngeneic tumor models (MC38, B16-F10), serum cytokine and tumor growth assays\",\n      \"pmids\": [\"41419196\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"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\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"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.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"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\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 8, 9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0382551\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 1, 10]}\n    ],\n    \"complexes\": [\n      \"VRAC (LRRC8 volume-regulated anion channel)\"\n    ],\n    \"partners\": [\n      \"LRRC8A\",\n      \"LRRC8C\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}