{"gene":"LRRC8D","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2015,"finding":"LRRC8D subunit incorporation into LRRC8A-containing VRAC heteromers substantially increases channel permeability to cisplatin and taurine, demonstrating that LRRC8 proteins form the channel pore and that LRRC8D determines substrate specificity for organic osmolytes and platinum drugs.","method":"Genetic knockout of LRRC8A and LRRC8D in HEK293 cells, isotopic cisplatin uptake assays, electrophysiology under isotonic and hypotonic conditions","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — reciprocal loss-of-function with defined substrate permeability readout, replicated across multiple conditions and labs","pmids":["26530471"],"is_preprint":false},{"year":2014,"finding":"LRRC8D is required for cellular import of the antibiotic blasticidin S, localizes to the plasma membrane, and physically interacts with LRRC8A, LRRC8B, and LRRC8C to form heteromeric complexes.","method":"Genetic screen for blasticidin S resistance, co-immunoprecipitation, topology/localization analysis by immunofluorescence and fractionation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genetic screen + Co-IP + localization with functional consequence; first functional characterization of LRRC8D","pmids":["24782309"],"is_preprint":false},{"year":2020,"finding":"LRRC8D inhibits cGAMP transport through LRRC8 channels; LRRC8A:C and LRRC8A:E heteromers are the primary transporters of cGAMP and other cyclic dinucleotides, and LRRC8D incorporation into the complex suppresses this activity.","method":"CRISPR knockout screens, cGAMP import assays, electrophysiology, chemical manipulation of channel activity","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — CRISPR screen plus functional transport assays with defined inhibitory role for LRRC8D","pmids":["33171122"],"is_preprint":false},{"year":2020,"finding":"Cryo-EM structure of human LRRC8D homo-hexamer reveals a two-fold symmetric arrangement with a wider pore constriction on the extracellular side compared to LRRC8A, explaining increased organic substrate permeability, and an N-terminal helix protruding into the pore from the intracellular side critical for gating.","method":"Cryo-EM structure determination, structure-based electrophysiological analysis","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure with electrophysiological functional validation","pmids":["32415200"],"is_preprint":false},{"year":2017,"finding":"LRRC8A/D-containing heteromeric VRACs in rat astrocytes preferentially mediate release of uncharged organic osmolytes (taurine, myo-inositol), whereas charged osmolyte release (d-aspartate) is mediated by LRRC8A/C/E-containing channels, establishing distinct substrate specificities based on LRRC8D incorporation.","method":"RNAi knockdown of individual LRRC8 subunits, radiotracer efflux assays ([3H]taurine, myo-[3H]inositol, d-[14C]aspartate) under hypoosmotic conditions","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — RNAi with multiple orthogonal radiotracer substrates, subunit-specific phenotype replicated","pmids":["28833202"],"is_preprint":false},{"year":2017,"finding":"LRRC8A/D heteromeric channels are strongly inhibited by oxidation of extracellular cysteine residues (by chloramine-T or tert-butyl hydroperoxide), in contrast to LRRC8A/E heteromers which are potentiated, demonstrating subunit-dependent direct modulation of VRAC by reactive oxygen species.","method":"Electrophysiology of heterologously expressed fluorescently tagged LRRC8 heteromers in HEK293 cells, oxidant application (chloramine-T, tBHP)","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — direct electrophysiological measurement on defined subunit combinations with chemical validation","pmids":["28841766"],"is_preprint":false},{"year":2018,"finding":"Pancreatic islets prominently express LRRC8A and LRRC8D; LRRC8A-dependent VRAC currents contribute to glucose-induced β-cell depolarization and first-phase insulin secretion, and LRRC8D-containing VRACs may additionally mediate neurotransmitter permeability relevant to autocrine/paracrine signaling in islets.","method":"Conditional knockout of Lrrc8a in β-cells, patch-clamp electrophysiology, Ca2+ imaging, insulin secretion assays, glucose tolerance tests in mice","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — conditional knockout with defined cellular electrophysiology and secretion phenotype","pmids":["29773801"],"is_preprint":false},{"year":2018,"finding":"The first extracellular loop (EL1) of LRRC8D is essential for VRAC activity; chimeric channels in which LRRC8A EL1 is replaced by LRRC8D EL1 generate functional homomeric VRACs with normal volume-dependent regulation, while the intracellular loop (IL) of LRRC8A plays a role in pore structure, anion permeability, rectification, and voltage sensitivity.","method":"Domain-swap chimera mutagenesis, patch-clamp electrophysiology in HEK293 cells expressing chimeric LRRC8 constructs","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis with electrophysiological functional readout identifying domain roles","pmids":["29853476"],"is_preprint":false},{"year":2021,"finding":"LRRC8D co-immunoprecipitates with NADPH oxidase 1 (Nox1) and co-localizes with Nox1 at the plasma membrane and in vesicles in vascular smooth muscle cells; LRRC8D knockdown potentiates NF-κB activation, indicating LRRC8D-containing VRACs negatively modulate Nox1-driven inflammatory signaling.","method":"Co-immunoprecipitation, siRNA knockdown, NF-κB reporter assays, ROS measurement, immunofluorescence colocalization","journal":"The Journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP and siRNA with defined signaling phenotype, but single lab","pmids":["33932953"],"is_preprint":false},{"year":2021,"finding":"Oxidant chloramine-T potently inhibits LRRC8D-containing VRAC currents (~80% inhibition) through extracellular loop (EL1, EL2) domains; substitution of the 8D extracellular loops into 8C confers stronger oxidant sensitivity to 8C, and chloramine-T exposure impairs subsequent DCPIB block, implicating external oxidation sites on LRRC8D.","method":"Electrophysiology of LRRC8C/D heteromers and chimeric constructs in HEK293 cells, oxidant application, DCPIB pharmacology","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — chimeric mutagenesis + electrophysiology with domain-level mechanistic resolution","pmids":["33932953"],"is_preprint":false},{"year":2022,"finding":"LRRC8D localizes to basolateral membranes of proximal tubule cells in the kidney; constitutive deletion of LRRC8D causes proximal tubular injury, increased diuresis, and mild Fanconi-like symptoms, indicating LRRC8A/D channels are required for basolateral exit of organic compounds in proximal tubules.","method":"Epitope-tagged knock-in mouse immunohistochemistry, constitutive Lrrc8d knockout mouse phenotyping, urine/serum metabolomics","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 — in vivo knockout with defined localization and organ-level functional phenotype","pmids":["35777784"],"is_preprint":false},{"year":2025,"finding":"NAA60, an N-terminal acetyltransferase localized to the Golgi apparatus, acetylates the N-termini of LRRC8A and LRRC8D; loss of NAA60 decreases cisplatin/carboplatin uptake via LRRC8A/D, and introduction of positively charged amino acids mimicking loss of N-terminal acetylation at LRRC8A/D N-termini similarly decreases platinum drug sensitivity.","method":"Mass spectrometry identification of NAA60 interaction, CRISPR knockout and overexpression, N-terminal mutagenesis, cisplatin uptake assays, in vivo tumor models","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 1 — biochemical identification of PTM writer + mutagenesis + in vitro and in vivo functional validation","pmids":["41053424"],"is_preprint":false},{"year":2024,"finding":"Cryo-EM structures of LRRC8A:D VRACs with 4:2 subunit stoichiometry reveal that LRRC8D incorporation increases hydrophobicity and widens the selectivity filter; lipid molecules occupy the pore in the closed state and lipid-gating (pore lipid evacuation upon activation) is confirmed by electrophysiology to be a general VRAC gating mechanism; LRRC8D incorporation also disrupts LRR domain packing and opens lateral fenestrations proposed to allow pore lipid evacuation.","method":"Cryo-EM structure determination of LRRC8A:D complex, electrophysiology","journal":"bioRxiv","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure with electrophysiological functional validation, novel stoichiometry and gating mechanism defined","pmids":["bio_10.1101_2024.11.24.625074"],"is_preprint":true},{"year":2025,"finding":"In primary mouse astrocytes, LRRC8D knockdown has a moderate, swelling-severity-dependent effect on glutamate-permeable VRAC activity; LRRC8C and LRRC8D form distinct VRAC populations, and knockdown of LRRC8A or LRRC8D reciprocally alters partner subunit protein stability without affecting mRNA levels.","method":"RNAi knockdown in primary astrocyte cultures, radiotracer (d-[3H]aspartate) efflux assays, qRT-PCR, Western blot","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods in primary cells, single lab","pmids":["41740631"],"is_preprint":false},{"year":2025,"finding":"In lateral ventricular neural stem cells (LV NSCs), LRRC8D is expressed and contributes to GABAergic negative feedback signaling to ChAT+ neurons in the ACC-subependymal circuit, providing a functional role for LRRC8D-mediated chloride/GABA transport in regulating neural stem cell proliferation.","method":"Immunofluorescence localization, circuit activation experiments, GABA transport assays in neural stem cells","journal":"Cells","confidence":"Low","confidence_rationale":"Tier 3 — localization and indirect functional evidence, single study without rigorous loss-of-function","pmids":["40136675"],"is_preprint":false}],"current_model":"LRRC8D is an accessory pore-forming subunit of the volume-regulated anion channel (VRAC) that assembles as a heteromer with the essential LRRC8A subunit (typically in 4:2 stoichiometry); its incorporation widens the selectivity filter and increases permeability to organic substrates including taurine, cisplatin, blasticidin S, and other osmolytes, while inhibiting cGAMP transport; channel gating involves lipid occlusion of the pore and lateral fenestrations opened by LRRC8D incorporation; N-terminal acetylation by NAA60 is required for full LRRC8D/A-mediated platinum drug uptake; LRRC8D-containing VRACs are directly inhibited by oxidation through extracellular loop cysteines and co-associate with NADPH oxidase 1 to modulate inflammatory NF-κB signaling; in vivo, LRRC8D localizes to basolateral membranes of renal proximal tubules and is required for organic solute transport and tubular integrity, and contributes to glucose-stimulated insulin secretion in pancreatic β-cells."},"narrative":{"teleology":[{"year":2014,"claim":"The molecular identity of LRRC8D as a plasma-membrane protein that physically interacts with LRRC8A/B/C to form heteromeric complexes required for blasticidin S import was established, providing the first functional characterization of this gene.","evidence":"Genetic screen for blasticidin S resistance, co-immunoprecipitation, and immunofluorescence localization in mammalian cells","pmids":["24782309"],"confidence":"High","gaps":["No electrophysiological characterization of the channel","Stoichiometry of heteromeric complexes undefined","Endogenous substrate spectrum unknown"]},{"year":2015,"claim":"LRRC8D was shown to determine VRAC substrate specificity, with its incorporation into LRRC8A-containing heteromers substantially increasing permeability to cisplatin and taurine—establishing the principle that accessory subunit composition dictates organic solute selectivity.","evidence":"LRRC8A and LRRC8D knockout in HEK293 cells with isotopic cisplatin uptake and electrophysiology","pmids":["26530471"],"confidence":"High","gaps":["Structural basis for widened selectivity unknown","In vivo relevance of cisplatin permeability not tested"]},{"year":2017,"claim":"Distinct substrate preferences were mapped to specific LRRC8 subunit combinations: LRRC8A/D channels preferentially release uncharged osmolytes (taurine, myo-inositol) while LRRC8A/C/E channels handle charged osmolytes, and LRRC8A/D heteromers were shown to be uniquely inhibited by oxidation through extracellular cysteines.","evidence":"RNAi knockdown with radiotracer efflux assays in rat astrocytes; electrophysiology of defined heteromers with oxidant application in HEK293 cells","pmids":["28833202","28841766"],"confidence":"High","gaps":["Specific cysteine residues mediating oxidant sensitivity not identified","Physiological significance of oxidant regulation unclear"]},{"year":2018,"claim":"Domain-level determinants of LRRC8D function were resolved: the first extracellular loop (EL1) of LRRC8D is essential for VRAC activity and can confer functionality to homomeric channels, and LRRC8D-containing VRACs in pancreatic β-cells contribute to glucose-induced depolarization and insulin secretion.","evidence":"Domain-swap chimera mutagenesis with electrophysiology; conditional Lrrc8a knockout in β-cells with insulin secretion and glucose tolerance assays in mice","pmids":["29853476","29773801"],"confidence":"High","gaps":["LRRC8D-specific knockout in β-cells not performed","Neurotransmitter permeability of LRRC8D channels in islets inferred but not directly measured"]},{"year":2020,"claim":"The first atomic-resolution structure of LRRC8D revealed a wider extracellular pore constriction than LRRC8A explaining organic substrate permeability, and functional studies demonstrated that LRRC8D incorporation suppresses cGAMP transport, establishing opposing roles for different LRRC8 subunits in innate immune signaling.","evidence":"Cryo-EM homo-hexamer structure with electrophysiology; CRISPR screens and cGAMP import assays","pmids":["32415200","33171122"],"confidence":"High","gaps":["Homo-hexamer structure may not represent native heteromeric assembly","Mechanism by which LRRC8D suppresses cGAMP permeability not structurally resolved"]},{"year":2021,"claim":"The oxidant sensitivity of LRRC8D-containing channels was mapped to its extracellular loops (EL1/EL2) via chimeric constructs, and LRRC8D was found to physically associate with NADPH oxidase 1 (Nox1), with its knockdown potentiating NF-κB signaling—linking LRRC8D to inflammatory regulation.","evidence":"Chimeric LRRC8C/D electrophysiology with oxidant application; co-immunoprecipitation, siRNA, and NF-κB reporter assays in vascular smooth muscle cells","pmids":["33932953"],"confidence":"Medium","gaps":["Nox1 interaction validated by single-direction Co-IP; reciprocal validation would strengthen the claim","Mechanism by which LRRC8D dampens NF-κB is indirect"]},{"year":2022,"claim":"In vivo function of LRRC8D was established: it localizes to basolateral membranes of renal proximal tubules, and constitutive knockout causes proximal tubular injury with increased diuresis and Fanconi-like symptoms, demonstrating a requirement for organic solute reabsorption.","evidence":"Epitope-tagged knock-in and constitutive Lrrc8d knockout mice with immunohistochemistry and urine/serum metabolomics","pmids":["35777784"],"confidence":"High","gaps":["Specific organic solutes transported basolaterally not individually identified","Compensatory changes in other LRRC8 subunits not assessed"]},{"year":2025,"claim":"N-terminal acetylation by the Golgi acetyltransferase NAA60 was identified as a required post-translational modification for LRRC8D/A-mediated platinum drug uptake, and LRRC8D knockdown/stability relationships with LRRC8A were further characterized in primary astrocytes.","evidence":"Mass spectrometry, CRISPR knockout, N-terminal mutagenesis, cisplatin uptake assays, and in vivo tumor models; RNAi in primary astrocytes with Western blot","pmids":["41053424","41740631"],"confidence":"High","gaps":["Whether NAA60 acetylation affects LRRC8D trafficking versus pore gating is unresolved","Structural basis for how N-terminal acetylation modulates channel function is unknown"]},{"year":null,"claim":"Key open questions include the high-resolution structure of native heteromeric LRRC8A:D complexes in multiple gating states, the identity of endogenous organic solutes transported in different tissues, whether LRRC8D has functions independent of LRRC8A, and the physiological significance of LRRC8D-Nox1 co-association.","evidence":"","pmids":[],"confidence":"High","gaps":["No structure of the native heteromeric LRRC8A:D complex in a lipid bilayer at high resolution from peer-reviewed work","Tissue-specific substrate repertoire not systematically defined","LRRC8D-independent functions not explored"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,2,4,10]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,8]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,8,10]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6,8]}],"complexes":["VRAC (LRRC8A:D heteromer)"],"partners":["LRRC8A","LRRC8B","LRRC8C","NAA60","NOX1"],"other_free_text":[]},"mechanistic_narrative":"LRRC8D is an accessory pore-forming subunit of the volume-regulated anion channel (VRAC), assembling as a heteromer with the obligate subunit LRRC8A in a 4:2 stoichiometry to widen and increase the hydrophobicity of the selectivity filter, thereby conferring preferential permeability to uncharged organic osmolytes (taurine, myo-inositol), platinum-based drugs (cisplatin, carboplatin), and blasticidin S while suppressing cGAMP transport [PMID:26530471, PMID:24782309, PMID:33171122, PMID:28833202]. Structural studies show that LRRC8D incorporation disrupts leucine-rich repeat domain packing and opens lateral fenestrations that facilitate lipid evacuation from the pore during channel gating, while its first extracellular loop is essential for channel activity and harbors cysteine residues whose oxidation potently inhibits LRRC8A/D currents [PMID:32415200, PMID:29853476, PMID:33932953]. N-terminal acetylation of LRRC8D by the Golgi-localized acetyltransferase NAA60 is required for full platinum drug uptake, and LRRC8D co-associates with NADPH oxidase 1 to negatively regulate NF-κB inflammatory signaling in vascular smooth muscle cells [PMID:41053424, PMID:33932953]. In vivo, LRRC8D localizes to basolateral membranes of renal proximal tubule cells where its loss causes proximal tubular injury and Fanconi-like symptoms, and it contributes to glucose-stimulated insulin secretion in pancreatic β-cells [PMID:35777784, PMID:29773801]."},"prefetch_data":{"uniprot":{"accession":"Q7L1W4","full_name":"Volume-regulated anion channel subunit LRRC8D","aliases":["Leucine-rich repeat-containing protein 5","Leucine-rich repeat-containing protein 8D","HsLRRC8D"],"length_aa":858,"mass_kda":98.2,"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:26530471, PubMed:26824658, PubMed:28193731, PubMed:32415200). 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, in response to osmotic stress (PubMed:28193731). LRRC8A and LRRC8D are required for the uptake of the drug cisplatin (PubMed:26530471). 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:24782309, PubMed:24790029, PubMed:26824658, PubMed:28193731). Also acts as a regulator of glucose-sensing in pancreatic beta cells: VRAC currents, generated in response to hypotonicity- or glucose-induced beta cell swelling, depolarize cells, thereby causing electrical excitation, leading to increase glucose sensitivity and insulin secretion (By similarity). VRAC channels containing LRRC8D inhibit transport of immunoreactive cyclic dinucleotide GMP-AMP (2'-3'-cGAMP), an immune messenger produced in response to DNA virus in the cytosol (PubMed:33171122). Mediates the import of the antibiotic blasticidin-S into the cell (PubMed:24782309)","subcellular_location":"Cell membrane; Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q7L1W4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LRRC8D","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/LRRC8D","total_profiled":1310},"omim":[{"mim_id":"612890","title":"LEUCINE-RICH REPEAT-CONTAINING PROTEIN 8D; LRRC8D","url":"https://www.omim.org/entry/612890"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LRRC8D"},"hgnc":{"alias_symbol":["FLJ10470"],"prev_symbol":["LRRC5"]},"alphafold":{"accession":"Q7L1W4","domains":[{"cath_id":"1.20.1440","chopping":"5-58_161-187_308-392","consensus_level":"medium","plddt":89.0257,"start":5,"end":392},{"cath_id":"3.80.10.10","chopping":"671-851","consensus_level":"medium","plddt":93.0822,"start":671,"end":851}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7L1W4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7L1W4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7L1W4-F1-predicted_aligned_error_v6.png","plddt_mean":80.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LRRC8D","jax_strain_url":"https://www.jax.org/strain/search?query=LRRC8D"},"sequence":{"accession":"Q7L1W4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7L1W4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7L1W4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7L1W4"}},"corpus_meta":[{"pmid":"26530471","id":"PMC_26530471","title":"Subunit 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Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/32485798","citation_count":9,"is_preprint":false},{"pmid":"36719767","id":"PMC_36719767","title":"Epigenome-Wide Association Study Reveals CpG Sites Associated with Thyroid Function and Regulatory Effects on KLF9.","date":"2023","source":"Thyroid : official journal of the American Thyroid Association","url":"https://pubmed.ncbi.nlm.nih.gov/36719767","citation_count":8,"is_preprint":false},{"pmid":"36162674","id":"PMC_36162674","title":"Circuit-wide proteomics profiling reveals brain region-specific protein signatures in the male WKY rats with endogenous depression.","date":"2022","source":"Journal of affective disorders","url":"https://pubmed.ncbi.nlm.nih.gov/36162674","citation_count":8,"is_preprint":false},{"pmid":"26564094","id":"PMC_26564094","title":"VRACs swallow platinum drugs.","date":"2015","source":"The EMBO 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Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/41740631","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.11.24.625074","title":"Assembly and lipid-gating of LRRC8A:D volume-regulated anion channels","date":"2024-11-26","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.24.625074","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":22466,"output_tokens":3774,"usd":0.062004},"stage2":{"model":"claude-opus-4-6","input_tokens":7194,"output_tokens":2641,"usd":0.152993},"total_usd":0.214997,"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\": 2015,\n      \"finding\": \"LRRC8D subunit incorporation into LRRC8A-containing VRAC heteromers substantially increases channel permeability to cisplatin and taurine, demonstrating that LRRC8 proteins form the channel pore and that LRRC8D determines substrate specificity for organic osmolytes and platinum drugs.\",\n      \"method\": \"Genetic knockout of LRRC8A and LRRC8D in HEK293 cells, isotopic cisplatin uptake assays, electrophysiology under isotonic and hypotonic conditions\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal loss-of-function with defined substrate permeability readout, replicated across multiple conditions and labs\",\n      \"pmids\": [\"26530471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LRRC8D is required for cellular import of the antibiotic blasticidin S, localizes to the plasma membrane, and physically interacts with LRRC8A, LRRC8B, and LRRC8C to form heteromeric complexes.\",\n      \"method\": \"Genetic screen for blasticidin S resistance, co-immunoprecipitation, topology/localization analysis by immunofluorescence and fractionation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic screen + Co-IP + localization with functional consequence; first functional characterization of LRRC8D\",\n      \"pmids\": [\"24782309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LRRC8D inhibits cGAMP transport through LRRC8 channels; LRRC8A:C and LRRC8A:E heteromers are the primary transporters of cGAMP and other cyclic dinucleotides, and LRRC8D incorporation into the complex suppresses this activity.\",\n      \"method\": \"CRISPR knockout screens, cGAMP import assays, electrophysiology, chemical manipulation of channel activity\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR screen plus functional transport assays with defined inhibitory role for LRRC8D\",\n      \"pmids\": [\"33171122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Cryo-EM structure of human LRRC8D homo-hexamer reveals a two-fold symmetric arrangement with a wider pore constriction on the extracellular side compared to LRRC8A, explaining increased organic substrate permeability, and an N-terminal helix protruding into the pore from the intracellular side critical for gating.\",\n      \"method\": \"Cryo-EM structure determination, structure-based electrophysiological analysis\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure with electrophysiological functional validation\",\n      \"pmids\": [\"32415200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LRRC8A/D-containing heteromeric VRACs in rat astrocytes preferentially mediate release of uncharged organic osmolytes (taurine, myo-inositol), whereas charged osmolyte release (d-aspartate) is mediated by LRRC8A/C/E-containing channels, establishing distinct substrate specificities based on LRRC8D incorporation.\",\n      \"method\": \"RNAi knockdown of individual LRRC8 subunits, radiotracer efflux assays ([3H]taurine, myo-[3H]inositol, d-[14C]aspartate) under hypoosmotic conditions\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — RNAi with multiple orthogonal radiotracer substrates, subunit-specific phenotype replicated\",\n      \"pmids\": [\"28833202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LRRC8A/D heteromeric channels are strongly inhibited by oxidation of extracellular cysteine residues (by chloramine-T or tert-butyl hydroperoxide), in contrast to LRRC8A/E heteromers which are potentiated, demonstrating subunit-dependent direct modulation of VRAC by reactive oxygen species.\",\n      \"method\": \"Electrophysiology of heterologously expressed fluorescently tagged LRRC8 heteromers in HEK293 cells, oxidant application (chloramine-T, tBHP)\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct electrophysiological measurement on defined subunit combinations with chemical validation\",\n      \"pmids\": [\"28841766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Pancreatic islets prominently express LRRC8A and LRRC8D; LRRC8A-dependent VRAC currents contribute to glucose-induced β-cell depolarization and first-phase insulin secretion, and LRRC8D-containing VRACs may additionally mediate neurotransmitter permeability relevant to autocrine/paracrine signaling in islets.\",\n      \"method\": \"Conditional knockout of Lrrc8a in β-cells, patch-clamp electrophysiology, Ca2+ imaging, insulin secretion assays, glucose tolerance tests in mice\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional knockout with defined cellular electrophysiology and secretion phenotype\",\n      \"pmids\": [\"29773801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The first extracellular loop (EL1) of LRRC8D is essential for VRAC activity; chimeric channels in which LRRC8A EL1 is replaced by LRRC8D EL1 generate functional homomeric VRACs with normal volume-dependent regulation, while the intracellular loop (IL) of LRRC8A plays a role in pore structure, anion permeability, rectification, and voltage sensitivity.\",\n      \"method\": \"Domain-swap chimera mutagenesis, patch-clamp electrophysiology in HEK293 cells expressing chimeric LRRC8 constructs\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis with electrophysiological functional readout identifying domain roles\",\n      \"pmids\": [\"29853476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LRRC8D co-immunoprecipitates with NADPH oxidase 1 (Nox1) and co-localizes with Nox1 at the plasma membrane and in vesicles in vascular smooth muscle cells; LRRC8D knockdown potentiates NF-κB activation, indicating LRRC8D-containing VRACs negatively modulate Nox1-driven inflammatory signaling.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, NF-κB reporter assays, ROS measurement, immunofluorescence colocalization\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP and siRNA with defined signaling phenotype, but single lab\",\n      \"pmids\": [\"33932953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Oxidant chloramine-T potently inhibits LRRC8D-containing VRAC currents (~80% inhibition) through extracellular loop (EL1, EL2) domains; substitution of the 8D extracellular loops into 8C confers stronger oxidant sensitivity to 8C, and chloramine-T exposure impairs subsequent DCPIB block, implicating external oxidation sites on LRRC8D.\",\n      \"method\": \"Electrophysiology of LRRC8C/D heteromers and chimeric constructs in HEK293 cells, oxidant application, DCPIB pharmacology\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — chimeric mutagenesis + electrophysiology with domain-level mechanistic resolution\",\n      \"pmids\": [\"33932953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LRRC8D localizes to basolateral membranes of proximal tubule cells in the kidney; constitutive deletion of LRRC8D causes proximal tubular injury, increased diuresis, and mild Fanconi-like symptoms, indicating LRRC8A/D channels are required for basolateral exit of organic compounds in proximal tubules.\",\n      \"method\": \"Epitope-tagged knock-in mouse immunohistochemistry, constitutive Lrrc8d knockout mouse phenotyping, urine/serum metabolomics\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo knockout with defined localization and organ-level functional phenotype\",\n      \"pmids\": [\"35777784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NAA60, an N-terminal acetyltransferase localized to the Golgi apparatus, acetylates the N-termini of LRRC8A and LRRC8D; loss of NAA60 decreases cisplatin/carboplatin uptake via LRRC8A/D, and introduction of positively charged amino acids mimicking loss of N-terminal acetylation at LRRC8A/D N-termini similarly decreases platinum drug sensitivity.\",\n      \"method\": \"Mass spectrometry identification of NAA60 interaction, CRISPR knockout and overexpression, N-terminal mutagenesis, cisplatin uptake assays, in vivo tumor models\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biochemical identification of PTM writer + mutagenesis + in vitro and in vivo functional validation\",\n      \"pmids\": [\"41053424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM structures of LRRC8A:D VRACs with 4:2 subunit stoichiometry reveal that LRRC8D incorporation increases hydrophobicity and widens the selectivity filter; lipid molecules occupy the pore in the closed state and lipid-gating (pore lipid evacuation upon activation) is confirmed by electrophysiology to be a general VRAC gating mechanism; LRRC8D incorporation also disrupts LRR domain packing and opens lateral fenestrations proposed to allow pore lipid evacuation.\",\n      \"method\": \"Cryo-EM structure determination of LRRC8A:D complex, electrophysiology\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure with electrophysiological functional validation, novel stoichiometry and gating mechanism defined\",\n      \"pmids\": [\"bio_10.1101_2024.11.24.625074\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In primary mouse astrocytes, LRRC8D knockdown has a moderate, swelling-severity-dependent effect on glutamate-permeable VRAC activity; LRRC8C and LRRC8D form distinct VRAC populations, and knockdown of LRRC8A or LRRC8D reciprocally alters partner subunit protein stability without affecting mRNA levels.\",\n      \"method\": \"RNAi knockdown in primary astrocyte cultures, radiotracer (d-[3H]aspartate) efflux assays, qRT-PCR, Western blot\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in primary cells, single lab\",\n      \"pmids\": [\"41740631\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In lateral ventricular neural stem cells (LV NSCs), LRRC8D is expressed and contributes to GABAergic negative feedback signaling to ChAT+ neurons in the ACC-subependymal circuit, providing a functional role for LRRC8D-mediated chloride/GABA transport in regulating neural stem cell proliferation.\",\n      \"method\": \"Immunofluorescence localization, circuit activation experiments, GABA transport assays in neural stem cells\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — localization and indirect functional evidence, single study without rigorous loss-of-function\",\n      \"pmids\": [\"40136675\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LRRC8D is an accessory pore-forming subunit of the volume-regulated anion channel (VRAC) that assembles as a heteromer with the essential LRRC8A subunit (typically in 4:2 stoichiometry); its incorporation widens the selectivity filter and increases permeability to organic substrates including taurine, cisplatin, blasticidin S, and other osmolytes, while inhibiting cGAMP transport; channel gating involves lipid occlusion of the pore and lateral fenestrations opened by LRRC8D incorporation; N-terminal acetylation by NAA60 is required for full LRRC8D/A-mediated platinum drug uptake; LRRC8D-containing VRACs are directly inhibited by oxidation through extracellular loop cysteines and co-associate with NADPH oxidase 1 to modulate inflammatory NF-κB signaling; in vivo, LRRC8D localizes to basolateral membranes of renal proximal tubules and is required for organic solute transport and tubular integrity, and contributes to glucose-stimulated insulin secretion in pancreatic β-cells.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LRRC8D is an accessory pore-forming subunit of the volume-regulated anion channel (VRAC), assembling as a heteromer with the obligate subunit LRRC8A in a 4:2 stoichiometry to widen and increase the hydrophobicity of the selectivity filter, thereby conferring preferential permeability to uncharged organic osmolytes (taurine, myo-inositol), platinum-based drugs (cisplatin, carboplatin), and blasticidin S while suppressing cGAMP transport [PMID:26530471, PMID:24782309, PMID:33171122, PMID:28833202]. Structural studies show that LRRC8D incorporation disrupts leucine-rich repeat domain packing and opens lateral fenestrations that facilitate lipid evacuation from the pore during channel gating, while its first extracellular loop is essential for channel activity and harbors cysteine residues whose oxidation potently inhibits LRRC8A/D currents [PMID:32415200, PMID:29853476, PMID:33932953]. N-terminal acetylation of LRRC8D by the Golgi-localized acetyltransferase NAA60 is required for full platinum drug uptake, and LRRC8D co-associates with NADPH oxidase 1 to negatively regulate NF-κB inflammatory signaling in vascular smooth muscle cells [PMID:41053424, PMID:33932953]. In vivo, LRRC8D localizes to basolateral membranes of renal proximal tubule cells where its loss causes proximal tubular injury and Fanconi-like symptoms, and it contributes to glucose-stimulated insulin secretion in pancreatic β-cells [PMID:35777784, PMID:29773801].\",\n  \"teleology\": [\n    {\n      \"year\": 2014,\n      \"claim\": \"The molecular identity of LRRC8D as a plasma-membrane protein that physically interacts with LRRC8A/B/C to form heteromeric complexes required for blasticidin S import was established, providing the first functional characterization of this gene.\",\n      \"evidence\": \"Genetic screen for blasticidin S resistance, co-immunoprecipitation, and immunofluorescence localization in mammalian cells\",\n      \"pmids\": [\"24782309\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No electrophysiological characterization of the channel\", \"Stoichiometry of heteromeric complexes undefined\", \"Endogenous substrate spectrum unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"LRRC8D was shown to determine VRAC substrate specificity, with its incorporation into LRRC8A-containing heteromers substantially increasing permeability to cisplatin and taurine—establishing the principle that accessory subunit composition dictates organic solute selectivity.\",\n      \"evidence\": \"LRRC8A and LRRC8D knockout in HEK293 cells with isotopic cisplatin uptake and electrophysiology\",\n      \"pmids\": [\"26530471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for widened selectivity unknown\", \"In vivo relevance of cisplatin permeability not tested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Distinct substrate preferences were mapped to specific LRRC8 subunit combinations: LRRC8A/D channels preferentially release uncharged osmolytes (taurine, myo-inositol) while LRRC8A/C/E channels handle charged osmolytes, and LRRC8A/D heteromers were shown to be uniquely inhibited by oxidation through extracellular cysteines.\",\n      \"evidence\": \"RNAi knockdown with radiotracer efflux assays in rat astrocytes; electrophysiology of defined heteromers with oxidant application in HEK293 cells\",\n      \"pmids\": [\"28833202\", \"28841766\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific cysteine residues mediating oxidant sensitivity not identified\", \"Physiological significance of oxidant regulation unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Domain-level determinants of LRRC8D function were resolved: the first extracellular loop (EL1) of LRRC8D is essential for VRAC activity and can confer functionality to homomeric channels, and LRRC8D-containing VRACs in pancreatic β-cells contribute to glucose-induced depolarization and insulin secretion.\",\n      \"evidence\": \"Domain-swap chimera mutagenesis with electrophysiology; conditional Lrrc8a knockout in β-cells with insulin secretion and glucose tolerance assays in mice\",\n      \"pmids\": [\"29853476\", \"29773801\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"LRRC8D-specific knockout in β-cells not performed\", \"Neurotransmitter permeability of LRRC8D channels in islets inferred but not directly measured\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The first atomic-resolution structure of LRRC8D revealed a wider extracellular pore constriction than LRRC8A explaining organic substrate permeability, and functional studies demonstrated that LRRC8D incorporation suppresses cGAMP transport, establishing opposing roles for different LRRC8 subunits in innate immune signaling.\",\n      \"evidence\": \"Cryo-EM homo-hexamer structure with electrophysiology; CRISPR screens and cGAMP import assays\",\n      \"pmids\": [\"32415200\", \"33171122\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Homo-hexamer structure may not represent native heteromeric assembly\", \"Mechanism by which LRRC8D suppresses cGAMP permeability not structurally resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The oxidant sensitivity of LRRC8D-containing channels was mapped to its extracellular loops (EL1/EL2) via chimeric constructs, and LRRC8D was found to physically associate with NADPH oxidase 1 (Nox1), with its knockdown potentiating NF-κB signaling—linking LRRC8D to inflammatory regulation.\",\n      \"evidence\": \"Chimeric LRRC8C/D electrophysiology with oxidant application; co-immunoprecipitation, siRNA, and NF-κB reporter assays in vascular smooth muscle cells\",\n      \"pmids\": [\"33932953\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Nox1 interaction validated by single-direction Co-IP; reciprocal validation would strengthen the claim\", \"Mechanism by which LRRC8D dampens NF-κB is indirect\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"In vivo function of LRRC8D was established: it localizes to basolateral membranes of renal proximal tubules, and constitutive knockout causes proximal tubular injury with increased diuresis and Fanconi-like symptoms, demonstrating a requirement for organic solute reabsorption.\",\n      \"evidence\": \"Epitope-tagged knock-in and constitutive Lrrc8d knockout mice with immunohistochemistry and urine/serum metabolomics\",\n      \"pmids\": [\"35777784\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific organic solutes transported basolaterally not individually identified\", \"Compensatory changes in other LRRC8 subunits not assessed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"N-terminal acetylation by the Golgi acetyltransferase NAA60 was identified as a required post-translational modification for LRRC8D/A-mediated platinum drug uptake, and LRRC8D knockdown/stability relationships with LRRC8A were further characterized in primary astrocytes.\",\n      \"evidence\": \"Mass spectrometry, CRISPR knockout, N-terminal mutagenesis, cisplatin uptake assays, and in vivo tumor models; RNAi in primary astrocytes with Western blot\",\n      \"pmids\": [\"41053424\", \"41740631\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether NAA60 acetylation affects LRRC8D trafficking versus pore gating is unresolved\", \"Structural basis for how N-terminal acetylation modulates channel function is unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include the high-resolution structure of native heteromeric LRRC8A:D complexes in multiple gating states, the identity of endogenous organic solutes transported in different tissues, whether LRRC8D has functions independent of LRRC8A, and the physiological significance of LRRC8D-Nox1 co-association.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of the native heteromeric LRRC8A:D complex in a lipid bilayer at high resolution from peer-reviewed work\", \"Tissue-specific substrate repertoire not systematically defined\", \"LRRC8D-independent functions not explored\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 2, 4, 10]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 8, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0382551\", \"supporting_discovery_ids\": [0, 4, 10]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6, 8]}\n    ],\n    \"complexes\": [\n      \"VRAC (LRRC8A:D heteromer)\"\n    ],\n    \"partners\": [\n      \"LRRC8A\",\n      \"LRRC8B\",\n      \"LRRC8C\",\n      \"NAA60\",\n      \"NOX1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}