{"gene":"LRRC8C","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2015,"finding":"LRRC8C is a subunit of heteromeric VRAC channels that determines substrate specificity; LRRC8A/D (but not LRRC8C) channels mediate cisplatin/carboplatin uptake and taurine permeability, while LRRC8C-containing channels do not contribute to platinum drug transport, demonstrating subunit-dependent permeation properties.","method":"Genetic knockout (CRISPR/siRNA) of individual LRRC8 subunits in HCT116 cells combined with drug uptake assays and electrophysiology","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — clean genetic KO with defined molecular phenotype, replicated across subunits","pmids":["26530471"],"is_preprint":false},{"year":2014,"finding":"LRRC8D physically interacts with LRRC8A, LRRC8B, and LRRC8C, supporting formation of heteromeric LRRC8 complexes at the plasma membrane that mediate small-molecule transport.","method":"Co-immunoprecipitation and topology/localization experiments in mammalian cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 — single lab Co-IP demonstrating LRRC8C interaction with LRRC8D and other subunits","pmids":["24782309"],"is_preprint":false},{"year":2016,"finding":"The C-terminal part of the first extracellular loop (EL1) of LRRC8C (and LRRC8E) is a major determinant of VRAC inactivation kinetics and anion selectivity, identified using chimeras between LRRC8C and LRRC8E and point mutations at conserved charged residues.","method":"Chimeric channel construction between LRRC8C and LRRC8E, point mutagenesis (charge reversal at Lys-98/Asp-100 equivalents), patch-clamp electrophysiology","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis + functional electrophysiology with multiple orthogonal constructs","pmids":["27325695"],"is_preprint":false},{"year":2017,"finding":"LRRC8A/C and LRRC8A/D heteromeric channels are inhibited by oxidation of intracellular cysteine residues, whereas LRRC8A/E heteromers are activated, demonstrating that LRRC8 channel proteins are directly and subunit-specifically modulated by reactive oxygen species.","method":"Heterologous expression of fluorescently tagged LRRC8 heteromers in HEK cells, whole-cell patch clamp, application of chloramine-T and tert-butyl hydroperoxide oxidants","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — direct pharmacological manipulation with electrophysiology, multiple subunit combinations tested","pmids":["28841766"],"is_preprint":false},{"year":2017,"finding":"In primary rat astrocytes, LRRC8A/C/E-containing (and LRRC8A/C/D/E) VRAC heteromers are the primary conduit for swelling-activated release of charged osmolytes (e.g., d-aspartate), whereas LRRC8A/D heteromers dominate uncharged osmolyte (taurine, myo-inositol) release, establishing subunit-dependent substrate selectivity.","method":"RNAi knockdown of individual LRRC8 subunits in primary rat astrocytes, radiotracer efflux assays under hypoosmotic conditions","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — systematic RNAi across all subunits with quantitative radiotracer assays, multiple osmolytes tested","pmids":["28833202"],"is_preprint":false},{"year":2018,"finding":"The first extracellular loop (EL1) of LRRC8C is essential for VRAC activity; replacing EL1 of LRRC8A with that of LRRC8C generates homomeric VRAC channels with normal volume-dependent regulation, and chimeric channels containing LRRC8A intracellular loop sequences in LRRC8C exhibit altered anion permeability, rectification, and voltage sensitivity.","method":"Chimeric channel construction (LRRC8C/LRRC8A EL1 and intracellular loop swaps), heterologous expression in LRRC8-null HCT116 cells, patch-clamp electrophysiology","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 — domain-swap mutagenesis with functional electrophysiology, multiple constructs validated","pmids":["29853476"],"is_preprint":false},{"year":2018,"finding":"MLC1 modulates VRAC activity in astrocytes indirectly; absence of MLC1 alters the phosphorylation state of the VRAC subunit LRRC8C, suggesting that MLC1/GlialCAM regulate LRRC8C via signal transduction pathways rather than direct protein-protein interaction.","method":"siRNA knockdown and overexpression of MLC1 in astrocytes, immunoprecipitation, co-localization studies, phosphorylation analysis, Xenopus oocyte expression","journal":"Neurobiology of disease","confidence":"Medium","confidence_rationale":"Tier 2/3 — indirect modulation shown by phosphorylation state change, supported by multiple assays but mechanism is indirect","pmids":["30076890"],"is_preprint":false},{"year":2020,"finding":"LRRC8A heteromeric channels containing LRRC8C and/or LRRC8E transport 2'3'-cGAMP and other cyclic dinucleotides bidirectionally as dictated by the electrochemical gradient; LRRC8D inhibits cGAMP transport. Activation by sphingosine 1-phosphate and inhibition by DCPIB modulate channel-mediated cGAMP transport.","method":"Genome-wide CRISPR screen, genetic KO, overexpression, cGAMP uptake/efflux assays, electrophysiology in multiple human cell lines","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — genome-wide CRISPR screen + genetic KO + functional transport assays, replicated across multiple cell types","pmids":["33171122"],"is_preprint":false},{"year":2021,"finding":"LRRC8C co-immunoprecipitates with NADPH oxidase 1 (Nox1) in vascular smooth muscle cells; LRRC8C knockdown inhibits TNFα-induced superoxide production, receptor endocytosis, NF-κB activation, and cell proliferation, identifying LRRC8A/C channels as oxidant-resistant complexes that support Nox1 activity at the plasma membrane.","method":"Co-immunoprecipitation, siRNA knockdown of LRRC8C in VSMCs, superoxide detection, NF-κB reporter assays, VRAC current recordings with chimeric EL1/EL2 domain swaps","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus loss-of-function with multiple downstream readouts, mechanistic chimera experiments","pmids":["33932953"],"is_preprint":false},{"year":2022,"finding":"LRRC8C is an essential VRAC subunit in T cells; its deletion abolishes VRAC currents and regulatory volume decrease (RVD). LRRC8C mediates uptake of 2'3'-cGAMP in T cells, activating STING and p53 signaling to inhibit T cell proliferation, survival, Ca2+ influx, and cytokine production.","method":"Lrrc8c-/- mouse model, electrophysiology (RVD assay), cGAMP transport assay, STING inhibitor experiments, p53 overexpression rescue, in vivo immune challenge models (influenza, EAE)","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO mouse with multiple orthogonal assays, pathway epistasis (STING inhibitor, p53 OE rescue), replicated in vivo","pmids":["35105987"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structure of murine LRRC8A/C heteromeric channels reveals hexameric assembly with a predominant A:C stoichiometry of 4:2; four LRRC8A subunits cluster in pairs stabilizing a closed state, while two LRRC8C subunits show greater flexibility and destabilize the tightly packed A subunits to enhance channel activation.","method":"Cryo-EM structural determination of heteromeric LRRC8A/C channels","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 — high-resolution cryo-EM structure with functional interpretation of LRRC8C role in activation","pmids":["36522427"],"is_preprint":false},{"year":2022,"finding":"Oxidation of the first methionine of LRRC8C (together with its LRR domain) mediates inhibition of LRRC8A/C heteromeric channels by reactive oxygen species, distinct from the cysteine-dependent activation mechanism in LRRC8E-containing channels.","method":"Chimeric and concatemeric LRRC8 channel strategies, mutagenesis of specific cysteines/methionines, whole-cell patch clamp","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — site-directed mutagenesis with electrophysiology, multiple chimeric constructs, identified specific residue","pmids":["35861288"],"is_preprint":false},{"year":2022,"finding":"LRRC8C is exclusively expressed in the vascular endothelium of the kidney, where (unlike LRRC8A/D) it does not appear to serve the proximal tubule transport functions required for renal integrity, establishing tissue-specific and subunit-specific VRAC composition.","method":"Epitope-tagged LRRC8 knock-in mice, immunohistochemistry/subcellular localization, constitutive and conditional subunit knockout mice with renal phenotyping","journal":"Journal of the American Society of Nephrology","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization in knock-in mice with subunit-specific KO phenotyping, but LRRC8C renal role is primarily localization-based","pmids":["35777784"],"is_preprint":false},{"year":2024,"finding":"De novo gain-of-function variants in LRRC8C at the boundary between the pore and cytoplasmic domain cause constitutive channel activity (open at isotonic conditions) in heteromeric LRRC8A/C channels; cryo-EM of mutant proteins shows increased subunit flexibility consistent with destabilization of subunit interactions and impaired channel gating.","method":"Patient genetic analysis, cryo-EM of mutant LRRC8C proteins, heterologous expression in cells with electrophysiology (patch clamp at isotonic conditions)","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure plus functional electrophysiology of disease mutants, mechanistic gating conclusion","pmids":["39623139"],"is_preprint":false},{"year":2024,"finding":"cGAMP produced by tumor cells is transported via LRRC8C channels to activate STING in endothelial cells, enhancing lymphocyte recruitment and transendothelial migration; this mechanism is downstream of TET2-mediated IL-2/STAT5A-dependent upregulation of cGAS.","method":"Cgas/Sting-deficient mouse liver cancer models, in vivo tumor experiments, mechanistic pathway analysis with TET2/STAT5A/cGAS/LRRC8C genetic perturbations","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo genetic models with mechanistic pathway placement, but LRRC8C role is inferred from prior transport data","pmids":["38177099"],"is_preprint":false},{"year":2024,"finding":"HSV-1 protein UL56 targets LRRC8A and LRRC8C for proteasomal degradation, thereby inhibiting cGAMP uptake via VRAC and suppressing innate immune signaling.","method":"Viral infection experiments, proteasome inhibitor rescue, cGAMP uptake assays, genetic perturbation of LRRC8 subunits","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 — viral protein sufficient for LRRC8C degradation shown with proteasomal mechanism, functional rescue experiments","pmids":["38652659"],"is_preprint":false},{"year":2025,"finding":"In vascular endothelium, LRRC8A, LRRC8B, and LRRC8C form a heteromeric complex (with codependent protein stability); LRRC8C depletion reduces VRAC currents, inhibits AKT-eNOS phosphorylation, increases myogenic tone, impairs eNOS-dependent vasodilation, and exacerbates angiotensin-induced hypertension in Lrrc8c knockout mice.","method":"Epitope-tagged Lrrc8a and Lrrc8c knock-in mice for Co-IP, endothelium-specific knockout/knockdown, patch clamp, pressure myography, angiotensin hypertension model in vivo","journal":"Hypertension","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP in physiological knock-in model, KO mice with multiple vascular functional readouts and in vivo phenotype","pmids":["41636028"],"is_preprint":false},{"year":2025,"finding":"Zafirlukast and pranlukast inhibit LRRC8A/C heteromeric channels via binding sites at the N-terminal domain and inter-subunit fenestrae between TM helices 1 and 2; mutations in NTD, TM1, and TM2 alter sensitivity to both drugs, and conditions enhancing voltage-dependent inactivation increase drug sensitivity, suggesting these inhibitors promote channel inactivation by destabilizing protein-lipid interactions at the pore.","method":"Molecular dynamics simulations, AlphaFold3 docking, site-directed mutagenesis of NTD/TM1/TM2 in 8C-8A(IL125) chimeric and heteromeric 8A/8C channels, patch-clamp electrophysiology","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 1 — computational docking validated by mutagenesis and electrophysiology, multiple structurally distinct drugs tested","pmids":["41053296"],"is_preprint":false},{"year":2025,"finding":"LRRC8A and LRRC8C are key components of glutamate-permeable VRACs in brain astrocytes; siRNA knockdown of LRRC8A or LRRC8C reduces swelling-activated D-aspartate release by ~85% and ~56%, respectively. Knockdown of LRRC8A or LRRC8C reciprocally reduces partner protein stability (without affecting mRNA), indicating mutual protein stabilization within the VRAC complex. LRRC8C- and LRRC8D-containing channels form distinct VRAC populations.","method":"qPCR, RNA-seq, RNAi knockdown, Western blot, radiotracer D-[3H]aspartate efflux assays in primary mouse astrocytes from WT and knockout mice","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 2 — systematic RNAi with multiple assays and double-knockdown epistasis, supported by protein stability analysis","pmids":["41740631"],"is_preprint":false}],"current_model":"LRRC8C is an obligatory auxiliary subunit of heteromeric Volume-Regulated Anion Channels (VRACs), forming hexameric complexes with the essential LRRC8A subunit (and sometimes LRRC8B) in a predominant 4A:2C stoichiometry; the two LRRC8C subunits destabilize the tightly packed LRRC8A subunits to promote channel activation, while the first extracellular loop and the pore-cytoplasmic domain boundary of LRRC8C determine inactivation kinetics, anion selectivity, and gating; LRRC8A/C channels are directly inhibited by oxidation of LRRC8C's N-terminal methionine and are resistant to further oxidation due to extracellular loop properties; in T cells and endothelial cells, LRRC8A/C complexes mediate bidirectional cGAMP transport to activate STING-p53 innate immune signaling, while in vascular endothelium they support AKT-eNOS signaling and vascular tone, and in brain astrocytes they constitute the primary glutamate-permeable VRAC population."},"narrative":{"teleology":[{"year":2014,"claim":"Establishing that LRRC8C is a physical component of heteromeric LRRC8 complexes answered whether VRAC subunits beyond LRRC8A interact directly, providing the first biochemical evidence for defined heteromeric assembly.","evidence":"Co-immunoprecipitation of LRRC8A, LRRC8B, LRRC8C, and LRRC8D in mammalian cells","pmids":["24782309"],"confidence":"Medium","gaps":["Single-lab Co-IP without reciprocal validation at the time","Stoichiometry and full subunit composition undetermined","Functional consequence of heteromeric assembly not yet tested"]},{"year":2015,"claim":"Demonstrating that LRRC8C-containing channels differ from LRRC8D-containing channels in substrate permeation (cisplatin/taurine excluded from LRRC8C channels) established the principle that auxiliary subunit identity dictates VRAC substrate selectivity.","evidence":"CRISPR/siRNA knockout of individual LRRC8 subunits in HCT116 cells with drug uptake assays and electrophysiology","pmids":["26530471"],"confidence":"High","gaps":["Structural basis for substrate selectivity unknown","Native heteromeric composition in tissues not yet defined"]},{"year":2016,"claim":"Mapping the C-terminal portion of the first extracellular loop (EL1) as the region controlling LRRC8C-dependent inactivation kinetics and anion selectivity answered where in the protein subunit identity encodes channel biophysical properties.","evidence":"Chimeric channels between LRRC8C and LRRC8E with charge-reversal point mutations, validated by patch-clamp electrophysiology","pmids":["27325695"],"confidence":"High","gaps":["Atomic-resolution structural interpretation of EL1 differences not available","In vivo relevance of inactivation kinetics not tested"]},{"year":2017,"claim":"Showing that LRRC8A/C channels are directly inhibited by reactive oxygen species — opposite to LRRC8A/E activation — revealed subunit-specific redox modulation of VRACs and positioned LRRC8C channels as oxidant-sensitive sensors.","evidence":"Whole-cell patch clamp of heterologously expressed LRRC8 heteromers exposed to chloramine-T and tert-butyl hydroperoxide","pmids":["28841766"],"confidence":"High","gaps":["Specific redox-sensitive residue not yet identified","Physiological redox conditions for modulation unclear"]},{"year":2017,"claim":"Establishing that LRRC8A/C/E channels are the primary conduit for swelling-activated glutamate/aspartate release in astrocytes, while LRRC8A/D channels handle uncharged osmolytes, clarified cell-type-specific VRAC function in the brain.","evidence":"Systematic RNAi knockdown of individual LRRC8 subunits in primary rat astrocytes with radiotracer efflux assays","pmids":["28833202"],"confidence":"High","gaps":["Relative contribution of LRRC8C vs. LRRC8E within the same complex unclear","In vivo brain phenotype of LRRC8C loss not tested"]},{"year":2018,"claim":"Domain-swap experiments showing that LRRC8C's EL1 can substitute for LRRC8A's EL1 to reconstitute functional homomeric VRACs, and that intracellular loops determine rectification and voltage sensitivity, delineated the modular architecture governing LRRC8C channel properties.","evidence":"Chimeric LRRC8C/LRRC8A channels expressed in LRRC8-null cells with patch-clamp electrophysiology","pmids":["29853476"],"confidence":"High","gaps":["Structural basis of modular loop function unresolved at atomic level","Native pore structure not yet determined"]},{"year":2020,"claim":"A genome-wide CRISPR screen identified LRRC8C (and LRRC8E) channels as bidirectional transporters of 2′3′-cGAMP, expanding VRAC function from osmolyte transport to innate immune second-messenger signaling.","evidence":"CRISPR screen, genetic KO, cGAMP uptake/efflux assays, and electrophysiology in multiple human cell lines","pmids":["33171122"],"confidence":"High","gaps":["Structural basis for cGAMP permeation through LRRC8C pore not defined","Relative contribution in physiological immune contexts not established"]},{"year":2022,"claim":"The cryo-EM structure of LRRC8A/C at 4:2 stoichiometry revealed that LRRC8C subunits introduce flexibility that destabilizes the closed conformation, providing the first atomic-level explanation for how auxiliary subunits promote channel activation.","evidence":"Cryo-EM structural determination of murine LRRC8A/C heteromeric channels","pmids":["36522427"],"confidence":"High","gaps":["Open-state structure not captured","How other LRRC8 family members alter stoichiometry or flexibility unknown"]},{"year":2022,"claim":"Identifying oxidation of the N-terminal methionine of LRRC8C as the specific residue mediating ROS-dependent channel inhibition resolved the molecular determinant of redox sensitivity first observed in 2017.","evidence":"Site-directed mutagenesis of methionines/cysteines in chimeric and concatemeric LRRC8 channels with patch-clamp electrophysiology","pmids":["35861288"],"confidence":"High","gaps":["Physiological relevance of methionine oxidation in disease not tested in vivo"]},{"year":2022,"claim":"Lrrc8c knockout mice revealed that LRRC8C is the essential non-LRRC8A subunit for VRAC activity in T cells, where cGAMP import via LRRC8A/C activates STING–p53 signaling to restrain T cell proliferation and cytokine production, connecting channel function to adaptive immunity.","evidence":"Lrrc8c−/− mouse model with electrophysiology, cGAMP transport assays, STING inhibitor epistasis, p53 rescue, and in vivo immune challenge (influenza, EAE)","pmids":["35105987"],"confidence":"High","gaps":["Whether LRRC8C-dependent cGAMP transport is relevant to autoimmune pathology in humans undetermined","Redundancy with LRRC8E in other immune cell types not fully explored"]},{"year":2024,"claim":"Discovery that de novo gain-of-function variants at the pore–cytoplasmic domain boundary of LRRC8C cause constitutive channel opening established LRRC8C as a disease gene and pinpointed this boundary as a critical gating element.","evidence":"Patient genetic analysis, cryo-EM of mutant proteins, and electrophysiology showing constitutive current at isotonic conditions","pmids":["39623139"],"confidence":"High","gaps":["Clinical phenotype and disease penetrance not fully characterized","Whether gain-of-function can be pharmacologically corrected unknown"]},{"year":2025,"claim":"Identifying that LRRC8A/C channels in vascular endothelium support AKT–eNOS signaling, vasodilation, and blood pressure homeostasis — with LRRC8C knockout mice showing exacerbated hypertension — connected VRAC activity to cardiovascular physiology.","evidence":"Epitope-tagged knock-in mice for reciprocal Co-IP, endothelial-specific knockout, patch clamp, pressure myography, angiotensin hypertension model","pmids":["41636028"],"confidence":"High","gaps":["Signal transduction mechanism linking VRAC activity to AKT phosphorylation not defined","Relative contribution of LRRC8B vs. LRRC8C in vascular endothelial VRACs unclear"]},{"year":2025,"claim":"Mapping zafirlukast/pranlukast binding sites to the N-terminal domain and inter-subunit fenestrae of LRRC8A/C channels provided the first pharmacological target sites validated by mutagenesis, establishing a framework for subunit-specific drug design.","evidence":"AlphaFold3 docking and molecular dynamics validated by site-directed mutagenesis of NTD/TM1/TM2 and patch-clamp electrophysiology","pmids":["41053296"],"confidence":"High","gaps":["Co-crystal or cryo-EM structure with bound inhibitor not yet obtained","Selectivity over other LRRC8 subunit combinations in vivo untested"]},{"year":null,"claim":"Key unresolved questions include the open-state structure of LRRC8A/C channels, the structural basis for selective cGAMP permeation, the identity of upstream signals coupling cell swelling to channel activation, the in vivo neural consequences of LRRC8C loss in astrocytes, and whether LRRC8C gain-of-function variants define a recognizable clinical syndrome.","evidence":"","pmids":[],"confidence":"Low","gaps":["No open-state cryo-EM structure","Molecular mechanism linking volume change to LRRC8C channel gating unknown","Astrocyte-specific LRRC8C knockout brain phenotype not reported"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,4,7,9,18]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,5,10,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,8,10,12,16]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[9,14,15]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,9,16]}],"complexes":["VRAC (LRRC8A/C hexamer)","VRAC (LRRC8A/B/C hexamer)"],"partners":["LRRC8A","LRRC8B","LRRC8D","LRRC8E","NOX1"],"other_free_text":[]},"mechanistic_narrative":"LRRC8C is an auxiliary subunit of volume-regulated anion channels (VRACs) that hetero-oligomerizes with the obligatory LRRC8A subunit (and LRRC8B) in a predominantly 4A:2C hexameric stoichiometry, in which the two LRRC8C subunits confer greater flexibility that destabilizes the closed channel conformation and promotes activation [PMID:36522427, PMID:29853476]. The first extracellular loop and pore–cytoplasmic domain boundary of LRRC8C are critical determinants of inactivation kinetics, anion selectivity, voltage gating, and pharmacological inhibitor binding, while oxidation of the N-terminal methionine of LRRC8C mediates redox-dependent channel inhibition [PMID:27325695, PMID:35861288, PMID:41053296]. LRRC8A/C channels selectively permeate charged osmolytes such as glutamate/aspartate in astrocytes and bidirectionally transport the immune second messenger 2′3′-cGAMP, thereby activating STING–p53 signaling in T cells and endothelial cells, supporting AKT–eNOS-dependent vasodilation, and enabling innate immune recognition of tumors [PMID:28833202, PMID:33171122, PMID:35105987, PMID:41636028]. De novo gain-of-function variants at the LRRC8C pore–cytoplasmic domain boundary cause constitutive channel opening, directly linking LRRC8C gating dysfunction to human disease [PMID:39623139]."},"prefetch_data":{"uniprot":{"accession":"Q8TDW0","full_name":"Volume-regulated anion channel subunit LRRC8C","aliases":["Factor for adipocyte differentiation 158","Leucine-rich repeat-containing protein 8C"],"length_aa":803,"mass_kda":92.5,"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, PubMed:36897307, PubMed:39623139). The VRAC channel conducts iodide better than chloride and can also conduct organic osmolytes like taurine (PubMed:24790029, PubMed:26824658, PubMed:28193731). Plays a redundant role in the efflux of amino acids, such as aspartate and glutamate, in response to osmotic stress (PubMed:24790029, PubMed:26824658, 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)","subcellular_location":"Cell membrane; Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q8TDW0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LRRC8C","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SCAMP2","stoichiometry":4.0},{"gene":"CANX","stoichiometry":0.2},{"gene":"NCLN","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LRRC8C","total_profiled":1310},"omim":[{"mim_id":"621056","title":"TELANGIECTASIA, IMPAIRED INTELLECTUAL DEVELOPMENT, MICROCEPHALY, METAPHYSEAL DYSPLASIA, EYE ABNORMALITIES, AND SHORT STATURE; TIMES","url":"https://www.omim.org/entry/621056"},{"mim_id":"612889","title":"LEUCINE-RICH REPEAT-CONTAINING PROTEIN 8C; LRRC8C","url":"https://www.omim.org/entry/612889"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Golgi apparatus","reliability":"Uncertain"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LRRC8C"},"hgnc":{"alias_symbol":["AD158"],"prev_symbol":[]},"alphafold":{"accession":"Q8TDW0","domains":[{"cath_id":"1.20.1440.80","chopping":"5-58_105-148_263-357","consensus_level":"medium","plddt":88.2062,"start":5,"end":357},{"cath_id":"3.80.10.10","chopping":"414-526_534-545","consensus_level":"medium","plddt":87.5684,"start":414,"end":545},{"cath_id":"3.80.10.10","chopping":"625-803","consensus_level":"medium","plddt":93.1774,"start":625,"end":803}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDW0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDW0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDW0-F1-predicted_aligned_error_v6.png","plddt_mean":83.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LRRC8C","jax_strain_url":"https://www.jax.org/strain/search?query=LRRC8C"},"sequence":{"accession":"Q8TDW0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TDW0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TDW0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDW0"}},"corpus_meta":[{"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":"35105987","id":"PMC_35105987","title":"The volume-regulated anion channel LRRC8C suppresses T cell function by regulating cyclic dinucleotide transport and STING-p53 signaling.","date":"2022","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/35105987","citation_count":92,"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":"38177099","id":"PMC_38177099","title":"TET2-mediated tumor cGAS triggers endothelial STING activation to regulate vasculature remodeling and anti-tumor immunity in liver cancer.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38177099","citation_count":73,"is_preprint":false},{"pmid":"24782309","id":"PMC_24782309","title":"The protein synthesis inhibitor blasticidin s enters mammalian cells via leucine-rich repeat-containing protein 8D.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24782309","citation_count":67,"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 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LRRC8A/D (but not LRRC8C) channels mediate cisplatin/carboplatin uptake and taurine permeability, while LRRC8C-containing channels do not contribute to platinum drug transport, demonstrating subunit-dependent permeation properties.\",\n      \"method\": \"Genetic knockout (CRISPR/siRNA) of individual LRRC8 subunits in HCT116 cells combined with drug uptake assays and electrophysiology\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic KO with defined molecular phenotype, replicated across subunits\",\n      \"pmids\": [\"26530471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LRRC8D physically interacts with LRRC8A, LRRC8B, and LRRC8C, supporting formation of heteromeric LRRC8 complexes at the plasma membrane that mediate small-molecule transport.\",\n      \"method\": \"Co-immunoprecipitation and topology/localization experiments in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab Co-IP demonstrating LRRC8C interaction with LRRC8D and other subunits\",\n      \"pmids\": [\"24782309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The C-terminal part of the first extracellular loop (EL1) of LRRC8C (and LRRC8E) is a major determinant of VRAC inactivation kinetics and anion selectivity, identified using chimeras between LRRC8C and LRRC8E and point mutations at conserved charged residues.\",\n      \"method\": \"Chimeric channel construction between LRRC8C and LRRC8E, point mutagenesis (charge reversal at Lys-98/Asp-100 equivalents), patch-clamp electrophysiology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis + functional electrophysiology with multiple orthogonal constructs\",\n      \"pmids\": [\"27325695\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LRRC8A/C and LRRC8A/D heteromeric channels are inhibited by oxidation of intracellular cysteine residues, whereas LRRC8A/E heteromers are activated, demonstrating that LRRC8 channel proteins are directly and subunit-specifically modulated by reactive oxygen species.\",\n      \"method\": \"Heterologous expression of fluorescently tagged LRRC8 heteromers in HEK cells, whole-cell patch clamp, application of chloramine-T and tert-butyl hydroperoxide oxidants\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct pharmacological manipulation with electrophysiology, multiple subunit combinations tested\",\n      \"pmids\": [\"28841766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In primary rat astrocytes, LRRC8A/C/E-containing (and LRRC8A/C/D/E) VRAC heteromers are the primary conduit for swelling-activated release of charged osmolytes (e.g., d-aspartate), whereas LRRC8A/D heteromers dominate uncharged osmolyte (taurine, myo-inositol) release, establishing subunit-dependent substrate selectivity.\",\n      \"method\": \"RNAi knockdown of individual LRRC8 subunits in primary rat astrocytes, radiotracer efflux assays under hypoosmotic conditions\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — systematic RNAi across all subunits with quantitative radiotracer assays, multiple osmolytes tested\",\n      \"pmids\": [\"28833202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The first extracellular loop (EL1) of LRRC8C is essential for VRAC activity; replacing EL1 of LRRC8A with that of LRRC8C generates homomeric VRAC channels with normal volume-dependent regulation, and chimeric channels containing LRRC8A intracellular loop sequences in LRRC8C exhibit altered anion permeability, rectification, and voltage sensitivity.\",\n      \"method\": \"Chimeric channel construction (LRRC8C/LRRC8A EL1 and intracellular loop swaps), heterologous expression in LRRC8-null HCT116 cells, patch-clamp electrophysiology\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — domain-swap mutagenesis with functional electrophysiology, multiple constructs validated\",\n      \"pmids\": [\"29853476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MLC1 modulates VRAC activity in astrocytes indirectly; absence of MLC1 alters the phosphorylation state of the VRAC subunit LRRC8C, suggesting that MLC1/GlialCAM regulate LRRC8C via signal transduction pathways rather than direct protein-protein interaction.\",\n      \"method\": \"siRNA knockdown and overexpression of MLC1 in astrocytes, immunoprecipitation, co-localization studies, phosphorylation analysis, Xenopus oocyte expression\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — indirect modulation shown by phosphorylation state change, supported by multiple assays but mechanism is indirect\",\n      \"pmids\": [\"30076890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LRRC8A heteromeric channels containing LRRC8C and/or LRRC8E transport 2'3'-cGAMP and other cyclic dinucleotides bidirectionally as dictated by the electrochemical gradient; LRRC8D inhibits cGAMP transport. Activation by sphingosine 1-phosphate and inhibition by DCPIB modulate channel-mediated cGAMP transport.\",\n      \"method\": \"Genome-wide CRISPR screen, genetic KO, overexpression, cGAMP uptake/efflux assays, electrophysiology in multiple human cell lines\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide CRISPR screen + genetic KO + functional transport assays, replicated across multiple cell types\",\n      \"pmids\": [\"33171122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LRRC8C co-immunoprecipitates with NADPH oxidase 1 (Nox1) in vascular smooth muscle cells; LRRC8C knockdown inhibits TNFα-induced superoxide production, receptor endocytosis, NF-κB activation, and cell proliferation, identifying LRRC8A/C channels as oxidant-resistant complexes that support Nox1 activity at the plasma membrane.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown of LRRC8C in VSMCs, superoxide detection, NF-κB reporter assays, VRAC current recordings with chimeric EL1/EL2 domain swaps\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus loss-of-function with multiple downstream readouts, mechanistic chimera experiments\",\n      \"pmids\": [\"33932953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LRRC8C is an essential VRAC subunit in T cells; its deletion abolishes VRAC currents and regulatory volume decrease (RVD). LRRC8C mediates uptake of 2'3'-cGAMP in T cells, activating STING and p53 signaling to inhibit T cell proliferation, survival, Ca2+ influx, and cytokine production.\",\n      \"method\": \"Lrrc8c-/- mouse model, electrophysiology (RVD assay), cGAMP transport assay, STING inhibitor experiments, p53 overexpression rescue, in vivo immune challenge models (influenza, EAE)\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO mouse with multiple orthogonal assays, pathway epistasis (STING inhibitor, p53 OE rescue), replicated in vivo\",\n      \"pmids\": [\"35105987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structure of murine LRRC8A/C heteromeric channels reveals hexameric assembly with a predominant A:C stoichiometry of 4:2; four LRRC8A subunits cluster in pairs stabilizing a closed state, while two LRRC8C subunits show greater flexibility and destabilize the tightly packed A subunits to enhance channel activation.\",\n      \"method\": \"Cryo-EM structural determination of heteromeric LRRC8A/C channels\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution cryo-EM structure with functional interpretation of LRRC8C role in activation\",\n      \"pmids\": [\"36522427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Oxidation of the first methionine of LRRC8C (together with its LRR domain) mediates inhibition of LRRC8A/C heteromeric channels by reactive oxygen species, distinct from the cysteine-dependent activation mechanism in LRRC8E-containing channels.\",\n      \"method\": \"Chimeric and concatemeric LRRC8 channel strategies, mutagenesis of specific cysteines/methionines, whole-cell patch clamp\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — site-directed mutagenesis with electrophysiology, multiple chimeric constructs, identified specific residue\",\n      \"pmids\": [\"35861288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LRRC8C is exclusively expressed in the vascular endothelium of the kidney, where (unlike LRRC8A/D) it does not appear to serve the proximal tubule transport functions required for renal integrity, establishing tissue-specific and subunit-specific VRAC composition.\",\n      \"method\": \"Epitope-tagged LRRC8 knock-in mice, immunohistochemistry/subcellular localization, constitutive and conditional subunit knockout mice with renal phenotyping\",\n      \"journal\": \"Journal of the American Society of Nephrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization in knock-in mice with subunit-specific KO phenotyping, but LRRC8C renal role is primarily localization-based\",\n      \"pmids\": [\"35777784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"De novo gain-of-function variants in LRRC8C at the boundary between the pore and cytoplasmic domain cause constitutive channel activity (open at isotonic conditions) in heteromeric LRRC8A/C channels; cryo-EM of mutant proteins shows increased subunit flexibility consistent with destabilization of subunit interactions and impaired channel gating.\",\n      \"method\": \"Patient genetic analysis, cryo-EM of mutant LRRC8C proteins, heterologous expression in cells with electrophysiology (patch clamp at isotonic conditions)\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure plus functional electrophysiology of disease mutants, mechanistic gating conclusion\",\n      \"pmids\": [\"39623139\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"cGAMP produced by tumor cells is transported via LRRC8C channels to activate STING in endothelial cells, enhancing lymphocyte recruitment and transendothelial migration; this mechanism is downstream of TET2-mediated IL-2/STAT5A-dependent upregulation of cGAS.\",\n      \"method\": \"Cgas/Sting-deficient mouse liver cancer models, in vivo tumor experiments, mechanistic pathway analysis with TET2/STAT5A/cGAS/LRRC8C genetic perturbations\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic models with mechanistic pathway placement, but LRRC8C role is inferred from prior transport data\",\n      \"pmids\": [\"38177099\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HSV-1 protein UL56 targets LRRC8A and LRRC8C for proteasomal degradation, thereby inhibiting cGAMP uptake via VRAC and suppressing innate immune signaling.\",\n      \"method\": \"Viral infection experiments, proteasome inhibitor rescue, cGAMP uptake assays, genetic perturbation of LRRC8 subunits\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — viral protein sufficient for LRRC8C degradation shown with proteasomal mechanism, functional rescue experiments\",\n      \"pmids\": [\"38652659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In vascular endothelium, LRRC8A, LRRC8B, and LRRC8C form a heteromeric complex (with codependent protein stability); LRRC8C depletion reduces VRAC currents, inhibits AKT-eNOS phosphorylation, increases myogenic tone, impairs eNOS-dependent vasodilation, and exacerbates angiotensin-induced hypertension in Lrrc8c knockout mice.\",\n      \"method\": \"Epitope-tagged Lrrc8a and Lrrc8c knock-in mice for Co-IP, endothelium-specific knockout/knockdown, patch clamp, pressure myography, angiotensin hypertension model in vivo\",\n      \"journal\": \"Hypertension\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP in physiological knock-in model, KO mice with multiple vascular functional readouts and in vivo phenotype\",\n      \"pmids\": [\"41636028\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Zafirlukast and pranlukast inhibit LRRC8A/C heteromeric channels via binding sites at the N-terminal domain and inter-subunit fenestrae between TM helices 1 and 2; mutations in NTD, TM1, and TM2 alter sensitivity to both drugs, and conditions enhancing voltage-dependent inactivation increase drug sensitivity, suggesting these inhibitors promote channel inactivation by destabilizing protein-lipid interactions at the pore.\",\n      \"method\": \"Molecular dynamics simulations, AlphaFold3 docking, site-directed mutagenesis of NTD/TM1/TM2 in 8C-8A(IL125) chimeric and heteromeric 8A/8C channels, patch-clamp electrophysiology\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — computational docking validated by mutagenesis and electrophysiology, multiple structurally distinct drugs tested\",\n      \"pmids\": [\"41053296\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LRRC8A and LRRC8C are key components of glutamate-permeable VRACs in brain astrocytes; siRNA knockdown of LRRC8A or LRRC8C reduces swelling-activated D-aspartate release by ~85% and ~56%, respectively. Knockdown of LRRC8A or LRRC8C reciprocally reduces partner protein stability (without affecting mRNA), indicating mutual protein stabilization within the VRAC complex. LRRC8C- and LRRC8D-containing channels form distinct VRAC populations.\",\n      \"method\": \"qPCR, RNA-seq, RNAi knockdown, Western blot, radiotracer D-[3H]aspartate efflux assays in primary mouse astrocytes from WT and knockout mice\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — systematic RNAi with multiple assays and double-knockdown epistasis, supported by protein stability analysis\",\n      \"pmids\": [\"41740631\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LRRC8C is an obligatory auxiliary subunit of heteromeric Volume-Regulated Anion Channels (VRACs), forming hexameric complexes with the essential LRRC8A subunit (and sometimes LRRC8B) in a predominant 4A:2C stoichiometry; the two LRRC8C subunits destabilize the tightly packed LRRC8A subunits to promote channel activation, while the first extracellular loop and the pore-cytoplasmic domain boundary of LRRC8C determine inactivation kinetics, anion selectivity, and gating; LRRC8A/C channels are directly inhibited by oxidation of LRRC8C's N-terminal methionine and are resistant to further oxidation due to extracellular loop properties; in T cells and endothelial cells, LRRC8A/C complexes mediate bidirectional cGAMP transport to activate STING-p53 innate immune signaling, while in vascular endothelium they support AKT-eNOS signaling and vascular tone, and in brain astrocytes they constitute the primary glutamate-permeable VRAC population.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LRRC8C is an auxiliary subunit of volume-regulated anion channels (VRACs) that hetero-oligomerizes with the obligatory LRRC8A subunit (and LRRC8B) in a predominantly 4A:2C hexameric stoichiometry, in which the two LRRC8C subunits confer greater flexibility that destabilizes the closed channel conformation and promotes activation [PMID:36522427, PMID:29853476]. The first extracellular loop and pore–cytoplasmic domain boundary of LRRC8C are critical determinants of inactivation kinetics, anion selectivity, voltage gating, and pharmacological inhibitor binding, while oxidation of the N-terminal methionine of LRRC8C mediates redox-dependent channel inhibition [PMID:27325695, PMID:35861288, PMID:41053296]. LRRC8A/C channels selectively permeate charged osmolytes such as glutamate/aspartate in astrocytes and bidirectionally transport the immune second messenger 2′3′-cGAMP, thereby activating STING–p53 signaling in T cells and endothelial cells, supporting AKT–eNOS-dependent vasodilation, and enabling innate immune recognition of tumors [PMID:28833202, PMID:33171122, PMID:35105987, PMID:41636028]. De novo gain-of-function variants at the LRRC8C pore–cytoplasmic domain boundary cause constitutive channel opening, directly linking LRRC8C gating dysfunction to human disease [PMID:39623139].\",\n  \"teleology\": [\n    {\n      \"year\": 2014,\n      \"claim\": \"Establishing that LRRC8C is a physical component of heteromeric LRRC8 complexes answered whether VRAC subunits beyond LRRC8A interact directly, providing the first biochemical evidence for defined heteromeric assembly.\",\n      \"evidence\": \"Co-immunoprecipitation of LRRC8A, LRRC8B, LRRC8C, and LRRC8D in mammalian cells\",\n      \"pmids\": [\"24782309\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab Co-IP without reciprocal validation at the time\", \"Stoichiometry and full subunit composition undetermined\", \"Functional consequence of heteromeric assembly not yet tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrating that LRRC8C-containing channels differ from LRRC8D-containing channels in substrate permeation (cisplatin/taurine excluded from LRRC8C channels) established the principle that auxiliary subunit identity dictates VRAC substrate selectivity.\",\n      \"evidence\": \"CRISPR/siRNA knockout of individual LRRC8 subunits in HCT116 cells with drug uptake assays and electrophysiology\",\n      \"pmids\": [\"26530471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for substrate selectivity unknown\", \"Native heteromeric composition in tissues not yet defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Mapping the C-terminal portion of the first extracellular loop (EL1) as the region controlling LRRC8C-dependent inactivation kinetics and anion selectivity answered where in the protein subunit identity encodes channel biophysical properties.\",\n      \"evidence\": \"Chimeric channels between LRRC8C and LRRC8E with charge-reversal point mutations, validated by patch-clamp electrophysiology\",\n      \"pmids\": [\"27325695\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution structural interpretation of EL1 differences not available\", \"In vivo relevance of inactivation kinetics not tested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showing that LRRC8A/C channels are directly inhibited by reactive oxygen species — opposite to LRRC8A/E activation — revealed subunit-specific redox modulation of VRACs and positioned LRRC8C channels as oxidant-sensitive sensors.\",\n      \"evidence\": \"Whole-cell patch clamp of heterologously expressed LRRC8 heteromers exposed to chloramine-T and tert-butyl hydroperoxide\",\n      \"pmids\": [\"28841766\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific redox-sensitive residue not yet identified\", \"Physiological redox conditions for modulation unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Establishing that LRRC8A/C/E channels are the primary conduit for swelling-activated glutamate/aspartate release in astrocytes, while LRRC8A/D channels handle uncharged osmolytes, clarified cell-type-specific VRAC function in the brain.\",\n      \"evidence\": \"Systematic RNAi knockdown of individual LRRC8 subunits in primary rat astrocytes with radiotracer efflux assays\",\n      \"pmids\": [\"28833202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of LRRC8C vs. LRRC8E within the same complex unclear\", \"In vivo brain phenotype of LRRC8C loss not tested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Domain-swap experiments showing that LRRC8C's EL1 can substitute for LRRC8A's EL1 to reconstitute functional homomeric VRACs, and that intracellular loops determine rectification and voltage sensitivity, delineated the modular architecture governing LRRC8C channel properties.\",\n      \"evidence\": \"Chimeric LRRC8C/LRRC8A channels expressed in LRRC8-null cells with patch-clamp electrophysiology\",\n      \"pmids\": [\"29853476\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of modular loop function unresolved at atomic level\", \"Native pore structure not yet determined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"A genome-wide CRISPR screen identified LRRC8C (and LRRC8E) channels as bidirectional transporters of 2′3′-cGAMP, expanding VRAC function from osmolyte transport to innate immune second-messenger signaling.\",\n      \"evidence\": \"CRISPR screen, genetic KO, cGAMP uptake/efflux assays, and electrophysiology in multiple human cell lines\",\n      \"pmids\": [\"33171122\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for cGAMP permeation through LRRC8C pore not defined\", \"Relative contribution in physiological immune contexts not established\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"The cryo-EM structure of LRRC8A/C at 4:2 stoichiometry revealed that LRRC8C subunits introduce flexibility that destabilizes the closed conformation, providing the first atomic-level explanation for how auxiliary subunits promote channel activation.\",\n      \"evidence\": \"Cryo-EM structural determination of murine LRRC8A/C heteromeric channels\",\n      \"pmids\": [\"36522427\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Open-state structure not captured\", \"How other LRRC8 family members alter stoichiometry or flexibility unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying oxidation of the N-terminal methionine of LRRC8C as the specific residue mediating ROS-dependent channel inhibition resolved the molecular determinant of redox sensitivity first observed in 2017.\",\n      \"evidence\": \"Site-directed mutagenesis of methionines/cysteines in chimeric and concatemeric LRRC8 channels with patch-clamp electrophysiology\",\n      \"pmids\": [\"35861288\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance of methionine oxidation in disease not tested in vivo\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Lrrc8c knockout mice revealed that LRRC8C is the essential non-LRRC8A subunit for VRAC activity in T cells, where cGAMP import via LRRC8A/C activates STING–p53 signaling to restrain T cell proliferation and cytokine production, connecting channel function to adaptive immunity.\",\n      \"evidence\": \"Lrrc8c−/− mouse model with electrophysiology, cGAMP transport assays, STING inhibitor epistasis, p53 rescue, and in vivo immune challenge (influenza, EAE)\",\n      \"pmids\": [\"35105987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether LRRC8C-dependent cGAMP transport is relevant to autoimmune pathology in humans undetermined\", \"Redundancy with LRRC8E in other immune cell types not fully explored\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery that de novo gain-of-function variants at the pore–cytoplasmic domain boundary of LRRC8C cause constitutive channel opening established LRRC8C as a disease gene and pinpointed this boundary as a critical gating element.\",\n      \"evidence\": \"Patient genetic analysis, cryo-EM of mutant proteins, and electrophysiology showing constitutive current at isotonic conditions\",\n      \"pmids\": [\"39623139\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Clinical phenotype and disease penetrance not fully characterized\", \"Whether gain-of-function can be pharmacologically corrected unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identifying that LRRC8A/C channels in vascular endothelium support AKT–eNOS signaling, vasodilation, and blood pressure homeostasis — with LRRC8C knockout mice showing exacerbated hypertension — connected VRAC activity to cardiovascular physiology.\",\n      \"evidence\": \"Epitope-tagged knock-in mice for reciprocal Co-IP, endothelial-specific knockout, patch clamp, pressure myography, angiotensin hypertension model\",\n      \"pmids\": [\"41636028\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signal transduction mechanism linking VRAC activity to AKT phosphorylation not defined\", \"Relative contribution of LRRC8B vs. LRRC8C in vascular endothelial VRACs unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Mapping zafirlukast/pranlukast binding sites to the N-terminal domain and inter-subunit fenestrae of LRRC8A/C channels provided the first pharmacological target sites validated by mutagenesis, establishing a framework for subunit-specific drug design.\",\n      \"evidence\": \"AlphaFold3 docking and molecular dynamics validated by site-directed mutagenesis of NTD/TM1/TM2 and patch-clamp electrophysiology\",\n      \"pmids\": [\"41053296\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Co-crystal or cryo-EM structure with bound inhibitor not yet obtained\", \"Selectivity over other LRRC8 subunit combinations in vivo untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the open-state structure of LRRC8A/C channels, the structural basis for selective cGAMP permeation, the identity of upstream signals coupling cell swelling to channel activation, the in vivo neural consequences of LRRC8C loss in astrocytes, and whether LRRC8C gain-of-function variants define a recognizable clinical syndrome.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No open-state cryo-EM structure\", \"Molecular mechanism linking volume change to LRRC8C channel gating unknown\", \"Astrocyte-specific LRRC8C knockout brain phenotype not reported\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 4, 7, 9, 18]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 5, 10, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 8, 10, 12, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0382551\", \"supporting_discovery_ids\": [0, 4, 7, 9, 18]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [9, 14, 15]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 9, 16]}\n    ],\n    \"complexes\": [\n      \"VRAC (LRRC8A/C hexamer)\",\n      \"VRAC (LRRC8A/B/C hexamer)\"\n    ],\n    \"partners\": [\n      \"LRRC8A\",\n      \"LRRC8B\",\n      \"LRRC8D\",\n      \"LRRC8E\",\n      \"NOX1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}