{"gene":"CLIC2","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":1997,"finding":"CLIC2 (then XAP121) was identified as a novel chloride intracellular channel gene located on Xq28, with its genomic structure determined; its protein product shares homology with bovine p64 chloride channel and human CLIC1 (NCC27), and encodes a 243 amino acid peptide.","method":"cDNA cloning, sequence alignment, genomic structure determination","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — sequence-based identification and genomic mapping, replicated by subsequent structural studies confirming GST-family membership","pmids":["9339381"],"is_preprint":false},{"year":2004,"finding":"CLIC2 inhibits cardiac ryanodine receptor (RyR2) Ca2+ release channels when added to the cytoplasmic side in lipid bilayers, and inhibits Ca2+ release from cardiac sarcoplasmic reticulum vesicles; inhibition is reversed by removal of CLIC2 or by anti-CLIC2 antibody. CLIC2 exists as a monomer, shows no thiol transferase activity, but exhibits low glutathione peroxidase activity.","method":"Lipid bilayer single-channel recording, Ca2+ efflux assay from SR vesicles, antibody reversal, enzyme activity assays","journal":"The international journal of biochemistry & cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays (lipid bilayer, Ca2+ efflux, antibody reversal) in one study; independently replicated by subsequent papers","pmids":["15147738"],"is_preprint":false},{"year":2007,"finding":"X-ray crystal structure of human CLIC2 at 1.8-Å resolution revealed: (1) CLIC2 belongs to the GST structural family in its water-soluble form; (2) unlike CLIC1, CLIC2 forms an intramolecular disulfide and remains monomeric regardless of redox conditions; (3) site-directed mutagenesis showed removal of the intramolecular disulfide or introduction of CLIC1-equivalent cysteines does not cause dimer formation; (4) CLIC2 forms pH-dependent chloride channels in vitro with higher activity at low pH and subject to redox regulation; (5) a 'foot-in-mouth' interaction where the foot loop inserts into an interdomain crevice of a neighboring molecule, suggesting a potential protein-recognition interface analogous to the GST active site (possibly for RyR binding).","method":"X-ray crystallography (1.8 Å), site-directed mutagenesis, in vitro channel recording","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure resolved at high resolution in two crystal forms, combined with mutagenesis and functional channel recording","pmids":["17945253"],"is_preprint":false},{"year":2008,"finding":"CLIC2's inhibitory effect on RyR2 is redox-dependent: under oxidizing conditions CLIC2 inhibits RyR2, but under reducing conditions CLIC2 activates RyR2. Both RyR2 and CLIC2 contain redox sensors, and the modulation requires redox-active GSH:GSSG buffer on both the luminal and cytoplasmic sides of the channel.","method":"Lipid bilayer single-channel recording with controlled GSH:GSSG redox buffer system","journal":"Antioxidants & redox signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — controlled lipid bilayer electrophysiology with redox manipulation, single lab, single method","pmids":["18522493"],"is_preprint":false},{"year":2009,"finding":"CLIC2 directly interacts with skeletal muscle ryanodine receptor (RyR1): it increases ryanodine binding affinity for RyR1 without changing maximal binding capacity, reduces Ca2+ efflux from SR vesicles, decreases RyR1 open probability by increasing mean closed time, and binds to a region between domains 5 and 6 in the clamp-shaped region of RyR1, inducing a conformational change (separation of domains 9 and 10) as revealed by cryo-EM.","method":"[3H]ryanodine binding assay, Ca2+ efflux assay, single-channel recording in lipid bilayer, cryo-electron microscopy","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (cryo-EM structural localization + ryanodine binding + Ca2+ efflux + single-channel recording) in one study definitively mapping the binding site and conformational change","pmids":["19356589"],"is_preprint":false},{"year":2011,"finding":"In silico modeling of the disease-associated H101Q mutation in CLIC2 showed it: (a) reduces flexibility of the joint loop important for normal CLIC2 function, (b) stabilizes the overall 3D structure thereby reducing the conformational change needed for soluble-to-membrane transition, and (c) removes a positively charged residue (H101) important for membrane association.","method":"In silico molecular dynamics simulation and electrostatics calculations","journal":"Proteins","confidence":"Low","confidence_rationale":"Tier 4 / Moderate — computational prediction only, no experimental validation of these specific structural effects; findings later supported by functional data in PMID:22814392","pmids":["21630357"],"is_preprint":false},{"year":2012,"finding":"The H101Q missense mutation in CLIC2 causes a gain-of-function effect on RyR channels: unlike wild-type CLIC2 which inhibits RyR activity, H101Q CLIC2 stimulates RyR channels, causing them to remain open for longer times and amplifying Ca2+-dependent signals. This was linked to X-linked intellectual disability, atrial fibrillation, cardiomegaly, and seizures in affected males.","method":"Exome sequencing (gene identification), functional lipid bilayer electrophysiology of RyR channels with H101Q mutant protein","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct functional assay demonstrating gain-of-function mechanism of mutation, combined with genetic evidence; findings consistent with prior mechanistic work on CLIC2-RyR interaction","pmids":["22814392"],"is_preprint":false},{"year":2017,"finding":"Wild-type CLIC2 and the H101Q mutant both increase the proportion of sub-conductance (submaximal) openings of RyR channels and reduce FKBP (FK506 binding protein) association with RyRs. With WT CLIC2, sub-conductance openings reduce net RyR current; with H101Q CLIC2, sub-conductance openings contribute to excess Ca2+ leak. FKBP and RyR isoform-specific effects of CLIC2, rapamycin, and FK506 on FKBP-RyR association were also demonstrated.","method":"Single-channel recording in lipid bilayer, FKBP-RyR binding assays, pharmacological manipulation (rapamycin, FK506)","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct electrophysiology and binding assays with both WT and mutant CLIC2, single lab, two orthogonal methods","pmids":["28851804"],"is_preprint":false},{"year":2022,"finding":"CLIC2 is secreted into the extracellular milieu from secretory granules. Secreted CLIC2 binds to MMP14 (membrane type-1 MMP) and inhibits its activity, leading to suppressed MMP2 activation, thereby potentially suppressing tumor cell invasion.","method":"Localization to secretory granules (fractionation/imaging implied), binding assay between CLIC2 and MMP14, MMP activity assay (as described in review citing primary data)","journal":"Cancers","confidence":"Low","confidence_rationale":"Tier 3 / Weak — mechanistic claims come from a review citing primary data not directly accessible in this abstract; single set of observations, no independent replication reported","pmids":["36230813"],"is_preprint":false},{"year":2025,"finding":"CLIC2 deletion in THP-1 monocytic cells (CLIC2 knock-out) does not affect monocyte morphology but causes macrophages to display increased membrane protrusions, upregulated CD11b/CD11c/CD80/CD86 markers, altered cytokine secretion (elevated CCL8, reduced IL-1β, IL-6, OPG), and increased Shp1 phosphorylation with concomitant loss of Stat3 phosphorylation. CLIC2 was shown to interact with both Shp1 and Stat3, suggesting CLIC2 regulates monocyte-to-macrophage differentiation via the Stat3 signaling pathway.","method":"CRISPR/genetic knock-out (THP-1CLIC2_KO), flow cytometry, cytokine secretion profiling, phosphorylation western blot, protein interaction (CLIC2 with Shp1 and Stat3)","journal":"Biology direct","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic KO with multiple orthogonal readouts (morphology, markers, cytokines, signaling phosphorylation, interaction), single lab, single study, no independent replication","pmids":["40696397"],"is_preprint":false}],"current_model":"CLIC2 is a GST-structural-family monomeric protein that, in its primary characterized role, acts as an inhibitor of ryanodine receptor (RyR1/RyR2) Ca2+ release channels by binding to the clamp-shaped region of RyR and stabilizing the closed state; this inhibition is redox-sensitive (inhibitory under oxidizing, activating under reducing conditions), and is abolished or converted to hyperactivation by the disease-causing H101Q mutation that causes a channelopathy with intellectual disability and cardiomegaly; additionally, CLIC2 can be secreted extracellularly to inhibit MMP14/MMP2, and intracellularly regulates macrophage differentiation through interactions with Shp1 and Stat3."},"narrative":{"mechanistic_narrative":"CLIC2 is a monomeric member of the GST structural family that functions principally as a regulator of intracellular Ca2+ release by binding and modulating ryanodine receptor channels [PMID:15147738, PMID:17945253, PMID:19356589]. In its water-soluble form CLIC2 adopts a GST fold, and unlike CLIC1 it forms an intramolecular disulfide and remains monomeric across redox conditions; it forms pH-dependent chloride channels in vitro that are more active at low pH and subject to redox regulation [PMID:17945253]. CLIC2 binds directly to the clamp-shaped region of RyR1 (between domains 5 and 6), inducing a conformational change, increasing ryanodine binding affinity, decreasing channel open probability by prolonging mean closed time, and reducing Ca2+ efflux from sarcoplasmic reticulum vesicles [PMID:19356589]; it acts comparably on cardiac RyR2 [PMID:15147738]. This modulation is redox-dependent, with CLIC2 inhibiting RyR2 under oxidizing conditions and activating it under reducing conditions, dependent on GSH:GSSG buffer on both luminal and cytoplasmic channel faces [PMID:18522493]. CLIC2 also promotes sub-conductance RyR openings and reduces FKBP association with RyRs [PMID:28851804]. The X-linked H101Q mutation converts CLIC2 from an RyR inhibitor into a gain-of-function activator that prolongs channel opening and amplifies Ca2+ signals, causing a channelopathy presenting with intellectual disability, atrial fibrillation, cardiomegaly, and seizures in affected males [PMID:22814392]. Beyond its RyR role, lower-confidence findings place CLIC2 in extracellular MMP14/MMP2 inhibition [PMID:36230813] and in macrophage differentiation via Shp1/Stat3 [PMID:40696397].","teleology":[{"year":1997,"claim":"Established the existence and genomic identity of CLIC2 as a candidate chloride channel gene, defining the molecular entity before any function was known.","evidence":"cDNA cloning, sequence alignment, and genomic structure determination mapping the gene to Xq28","pmids":["9339381"],"confidence":"Medium","gaps":["No functional or biochemical characterization of the protein","Homology-based annotation only; channel activity unproven"]},{"year":2004,"claim":"Answered what CLIC2 actually does by demonstrating it is an inhibitor of cardiac RyR2 Ca2+ release channels, shifting the protein from a presumed chloride channel to an RyR regulator.","evidence":"Lipid bilayer single-channel recording, SR vesicle Ca2+ efflux assay, and antibody reversal; enzyme activity assays showing low glutathione peroxidase but no thiol transferase activity","pmids":["15147738"],"confidence":"High","gaps":["RyR binding site not localized","Redox dependence of the interaction not yet defined"]},{"year":2007,"claim":"Resolved the structural basis of CLIC2, placing it in the GST structural family and explaining why it remains monomeric, while defining a candidate protein-recognition interface.","evidence":"1.8-Å X-ray crystallography in two crystal forms, site-directed mutagenesis, and in vitro channel recording","pmids":["17945253"],"confidence":"High","gaps":["The 'foot-in-mouth' interface as the RyR-binding site was inferred, not demonstrated","Soluble-to-membrane transition mechanism unresolved"]},{"year":2008,"claim":"Showed that CLIC2's effect on RyR is not fixed but redox-switched, establishing CLIC2 as a redox-sensitive bidirectional modulator.","evidence":"Lipid bilayer single-channel recording with controlled GSH:GSSG redox buffer on both channel faces","pmids":["18522493"],"confidence":"Medium","gaps":["Single lab, single method","Molecular identity of the redox sensor residues not mapped"]},{"year":2009,"claim":"Pinpointed where and how CLIC2 binds RyR1, converting a functional inhibition into a structurally defined interaction with a measured conformational consequence.","evidence":"[3H]ryanodine binding, Ca2+ efflux assay, lipid bilayer single-channel recording, and cryo-EM localization to the clamp region between domains 5 and 6","pmids":["19356589"],"confidence":"High","gaps":["Atomic-resolution contacts at the interface not resolved","Whether the same site mediates RyR2 binding not directly tested"]},{"year":2011,"claim":"Proposed a structural rationale for how the disease mutation H101Q alters CLIC2, framing it as a defect in conformational flexibility and membrane association.","evidence":"In silico molecular dynamics simulation and electrostatics calculations","pmids":["21630357"],"confidence":"Low","gaps":["Computational prediction only, no experimental validation of the predicted structural effects","Link to functional channel behavior not established at this stage"]},{"year":2012,"claim":"Connected CLIC2 to human disease and established the mutation mechanism: H101Q is a gain-of-function variant that activates rather than inhibits RyR, causing an X-linked channelopathy.","evidence":"Exome sequencing for gene identification plus functional lipid bilayer electrophysiology of RyR channels with H101Q mutant protein","pmids":["22814392"],"confidence":"High","gaps":["How loss of H101 produces activation rather than simple loss of inhibition not fully mechanistically resolved","Tissue-specific contributions to the multisystem phenotype unclear"]},{"year":2017,"claim":"Refined the mechanism by showing both WT and mutant CLIC2 promote sub-conductance RyR openings and displace FKBP, distinguishing how the same biophysical change yields opposite physiological outcomes.","evidence":"Lipid bilayer single-channel recording, FKBP-RyR binding assays, and pharmacological manipulation with rapamycin and FK506","pmids":["28851804"],"confidence":"Medium","gaps":["Single lab","Physiological relevance of FKBP displacement in vivo not established"]},{"year":2022,"claim":"Extended CLIC2 beyond intracellular Ca2+ signaling by reporting a secreted, extracellular role inhibiting MMP14 and downstream MMP2 activation.","evidence":"Secretory-granule localization, CLIC2–MMP14 binding assay, and MMP activity assay, as described in a review citing primary data","pmids":["36230813"],"confidence":"Low","gaps":["Mechanistic claims drawn from a review citing primary data, not independently replicated here","Secretion mechanism and physiological context underdefined"]},{"year":2025,"claim":"Identified an intracellular signaling role in immune-cell differentiation, linking CLIC2 to Shp1/Stat3 control of monocyte-to-macrophage transition.","evidence":"CRISPR knock-out in THP-1 cells with flow cytometry, cytokine profiling, phosphorylation westerns, and CLIC2 interaction assays with Shp1 and Stat3","pmids":["40696397"],"confidence":"Medium","gaps":["Single study, no independent replication","Direct vs. indirect nature of Shp1/Stat3 interactions not resolved","Relationship to the RyR/Ca2+ role unknown"]},{"year":null,"claim":"How CLIC2 transitions between its soluble GST-fold form, its membrane-inserted chloride-channel form, its RyR-bound regulatory form, and its secreted MMP-inhibitory form within a single cellular context remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model linking the channel, RyR-modulator, secreted, and signaling roles","Atomic structure of any CLIC2–partner complex unresolved","Endogenous redox conditions governing inhibition vs. activation in vivo not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,3,4]},{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[2]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[8]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,2]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[8]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[8]}],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[1,4]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[6]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,9]}],"complexes":[],"partners":["RYR1","RYR2","MMP14","PTPN6","STAT3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O15247","full_name":"Chloride intracellular channel protein 2","aliases":["Glutaredoxin-like oxidoreductase CLIC2","Glutaredoxin-like peroxidase CLIC2","XAP121"],"length_aa":247,"mass_kda":28.4,"function":"In the soluble state, catalyzes glutaredoxin-like thiol disulfide exchange reactions with reduced glutathione as electron donor. Displays weak glutathione peroxidase activity (Probable) (PubMed:25581026). Can insert into membranes and form chloride ion channels. Membrane insertion seems to be redox-regulated and may occur only under oxidizing conditions. Modulates the activity of RYR2 and inhibits calcium influx","subcellular_location":"Cytoplasm; Membrane","url":"https://www.uniprot.org/uniprotkb/O15247/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CLIC2","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/CLIC2","total_profiled":1310},"omim":[{"mim_id":"607293","title":"CHLORIDE INTRACELLULAR CHANNEL 5; CLIC5","url":"https://www.omim.org/entry/607293"},{"mim_id":"606536","title":"CHLORIDE INTRACELLULAR CHANNEL 4; CLIC4","url":"https://www.omim.org/entry/606536"},{"mim_id":"606533","title":"CHLORIDE INTRACELLULAR CHANNEL 3; CLIC3","url":"https://www.omim.org/entry/606533"},{"mim_id":"311510","title":"WAISMAN SYNDROME; WSMN","url":"https://www.omim.org/entry/311510"},{"mim_id":"300886","title":"INTELLECTUAL DEVELOPMENTAL DISORDER, X-LINKED, SYNDROMIC 32; MRXS32","url":"https://www.omim.org/entry/300886"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CLIC2"},"hgnc":{"alias_symbol":["XAP121","CLCNL2"],"prev_symbol":[]},"alphafold":{"accession":"O15247","domains":[{"cath_id":"3.40.30.10","chopping":"13-92","consensus_level":"high","plddt":93.5349,"start":13,"end":92},{"cath_id":"1.20.1050.10","chopping":"106-239","consensus_level":"high","plddt":96.4403,"start":106,"end":239}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O15247","model_url":"https://alphafold.ebi.ac.uk/files/AF-O15247-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O15247-F1-predicted_aligned_error_v6.png","plddt_mean":92.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CLIC2","jax_strain_url":"https://www.jax.org/strain/search?query=CLIC2"},"sequence":{"accession":"O15247","fasta_url":"https://rest.uniprot.org/uniprotkb/O15247.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O15247/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O15247"}},"corpus_meta":[{"pmid":"22814392","id":"PMC_22814392","title":"An X-linked channelopathy with cardiomegaly due to a CLIC2 mutation enhancing ryanodine receptor channel activity.","date":"2012","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22814392","citation_count":85,"is_preprint":false},{"pmid":"21630357","id":"PMC_21630357","title":"A missense mutation in CLIC2 associated with intellectual disability is predicted by in silico modeling to affect protein stability and dynamics.","date":"2011","source":"Proteins","url":"https://pubmed.ncbi.nlm.nih.gov/21630357","citation_count":71,"is_preprint":false},{"pmid":"15147738","id":"PMC_15147738","title":"CLIC-2 modulates cardiac ryanodine receptor Ca2+ release channels.","date":"2004","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15147738","citation_count":71,"is_preprint":false},{"pmid":"9339381","id":"PMC_9339381","title":"Genomic structure of a novel chloride channel gene, CLIC2, in Xq28.","date":"1997","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9339381","citation_count":63,"is_preprint":false},{"pmid":"17945253","id":"PMC_17945253","title":"Structure of the Janus protein human CLIC2.","date":"2007","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17945253","citation_count":62,"is_preprint":false},{"pmid":"19356589","id":"PMC_19356589","title":"CLIC2-RyR1 interaction and structural characterization by cryo-electron microscopy.","date":"2009","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19356589","citation_count":43,"is_preprint":false},{"pmid":"18522493","id":"PMC_18522493","title":"Redox potential and the response of cardiac ryanodine receptors to CLIC-2, a member of the glutathione S-transferase structural family.","date":"2008","source":"Antioxidants & redox signaling","url":"https://pubmed.ncbi.nlm.nih.gov/18522493","citation_count":29,"is_preprint":false},{"pmid":"28851804","id":"PMC_28851804","title":"Association of FK506 binding proteins with RyR channels - effect of CLIC2 binding on sub-conductance opening and FKBP binding.","date":"2017","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/28851804","citation_count":15,"is_preprint":false},{"pmid":"36230813","id":"PMC_36230813","title":"Chloride Intracellular Channel Proteins (CLICs) and Malignant Tumor Progression: A Focus on the Preventive Role of CLIC2 in Invasion and Metastasis.","date":"2022","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/36230813","citation_count":13,"is_preprint":false},{"pmid":"28862243","id":"PMC_28862243","title":"Association of anti-CLIC2 and anti-HMGB1 autoantibodies with higher disease activity in systemic lupus erythematosus patients.","date":"2017","source":"Journal of postgraduate medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28862243","citation_count":6,"is_preprint":false},{"pmid":"18007051","id":"PMC_18007051","title":"Expression, purification, crystallization and preliminary X-ray diffraction analysis of chloride intracellular channel 2 (CLIC2).","date":"2007","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/18007051","citation_count":6,"is_preprint":false},{"pmid":"29198705","id":"PMC_29198705","title":"Tilapia and human CLIC2 structures are highly conserved.","date":"2017","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/29198705","citation_count":4,"is_preprint":false},{"pmid":"40696397","id":"PMC_40696397","title":"CLIC2 regulates immunosuppression and macrophage differentiation in genomically stable gastric cancer.","date":"2025","source":"Biology direct","url":"https://pubmed.ncbi.nlm.nih.gov/40696397","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8158,"output_tokens":2883,"usd":0.03386,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10164,"output_tokens":3455,"usd":0.068598,"stage2_stop_reason":"end_turn"},"total_usd":0.102458,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"CLIC2 (then XAP121) was identified as a novel chloride intracellular channel gene located on Xq28, with its genomic structure determined; its protein product shares homology with bovine p64 chloride channel and human CLIC1 (NCC27), and encodes a 243 amino acid peptide.\",\n      \"method\": \"cDNA cloning, sequence alignment, genomic structure determination\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — sequence-based identification and genomic mapping, replicated by subsequent structural studies confirming GST-family membership\",\n      \"pmids\": [\"9339381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CLIC2 inhibits cardiac ryanodine receptor (RyR2) Ca2+ release channels when added to the cytoplasmic side in lipid bilayers, and inhibits Ca2+ release from cardiac sarcoplasmic reticulum vesicles; inhibition is reversed by removal of CLIC2 or by anti-CLIC2 antibody. CLIC2 exists as a monomer, shows no thiol transferase activity, but exhibits low glutathione peroxidase activity.\",\n      \"method\": \"Lipid bilayer single-channel recording, Ca2+ efflux assay from SR vesicles, antibody reversal, enzyme activity assays\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays (lipid bilayer, Ca2+ efflux, antibody reversal) in one study; independently replicated by subsequent papers\",\n      \"pmids\": [\"15147738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"X-ray crystal structure of human CLIC2 at 1.8-Å resolution revealed: (1) CLIC2 belongs to the GST structural family in its water-soluble form; (2) unlike CLIC1, CLIC2 forms an intramolecular disulfide and remains monomeric regardless of redox conditions; (3) site-directed mutagenesis showed removal of the intramolecular disulfide or introduction of CLIC1-equivalent cysteines does not cause dimer formation; (4) CLIC2 forms pH-dependent chloride channels in vitro with higher activity at low pH and subject to redox regulation; (5) a 'foot-in-mouth' interaction where the foot loop inserts into an interdomain crevice of a neighboring molecule, suggesting a potential protein-recognition interface analogous to the GST active site (possibly for RyR binding).\",\n      \"method\": \"X-ray crystallography (1.8 Å), site-directed mutagenesis, in vitro channel recording\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure resolved at high resolution in two crystal forms, combined with mutagenesis and functional channel recording\",\n      \"pmids\": [\"17945253\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CLIC2's inhibitory effect on RyR2 is redox-dependent: under oxidizing conditions CLIC2 inhibits RyR2, but under reducing conditions CLIC2 activates RyR2. Both RyR2 and CLIC2 contain redox sensors, and the modulation requires redox-active GSH:GSSG buffer on both the luminal and cytoplasmic sides of the channel.\",\n      \"method\": \"Lipid bilayer single-channel recording with controlled GSH:GSSG redox buffer system\",\n      \"journal\": \"Antioxidants & redox signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — controlled lipid bilayer electrophysiology with redox manipulation, single lab, single method\",\n      \"pmids\": [\"18522493\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CLIC2 directly interacts with skeletal muscle ryanodine receptor (RyR1): it increases ryanodine binding affinity for RyR1 without changing maximal binding capacity, reduces Ca2+ efflux from SR vesicles, decreases RyR1 open probability by increasing mean closed time, and binds to a region between domains 5 and 6 in the clamp-shaped region of RyR1, inducing a conformational change (separation of domains 9 and 10) as revealed by cryo-EM.\",\n      \"method\": \"[3H]ryanodine binding assay, Ca2+ efflux assay, single-channel recording in lipid bilayer, cryo-electron microscopy\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (cryo-EM structural localization + ryanodine binding + Ca2+ efflux + single-channel recording) in one study definitively mapping the binding site and conformational change\",\n      \"pmids\": [\"19356589\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In silico modeling of the disease-associated H101Q mutation in CLIC2 showed it: (a) reduces flexibility of the joint loop important for normal CLIC2 function, (b) stabilizes the overall 3D structure thereby reducing the conformational change needed for soluble-to-membrane transition, and (c) removes a positively charged residue (H101) important for membrane association.\",\n      \"method\": \"In silico molecular dynamics simulation and electrostatics calculations\",\n      \"journal\": \"Proteins\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Moderate — computational prediction only, no experimental validation of these specific structural effects; findings later supported by functional data in PMID:22814392\",\n      \"pmids\": [\"21630357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The H101Q missense mutation in CLIC2 causes a gain-of-function effect on RyR channels: unlike wild-type CLIC2 which inhibits RyR activity, H101Q CLIC2 stimulates RyR channels, causing them to remain open for longer times and amplifying Ca2+-dependent signals. This was linked to X-linked intellectual disability, atrial fibrillation, cardiomegaly, and seizures in affected males.\",\n      \"method\": \"Exome sequencing (gene identification), functional lipid bilayer electrophysiology of RyR channels with H101Q mutant protein\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct functional assay demonstrating gain-of-function mechanism of mutation, combined with genetic evidence; findings consistent with prior mechanistic work on CLIC2-RyR interaction\",\n      \"pmids\": [\"22814392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Wild-type CLIC2 and the H101Q mutant both increase the proportion of sub-conductance (submaximal) openings of RyR channels and reduce FKBP (FK506 binding protein) association with RyRs. With WT CLIC2, sub-conductance openings reduce net RyR current; with H101Q CLIC2, sub-conductance openings contribute to excess Ca2+ leak. FKBP and RyR isoform-specific effects of CLIC2, rapamycin, and FK506 on FKBP-RyR association were also demonstrated.\",\n      \"method\": \"Single-channel recording in lipid bilayer, FKBP-RyR binding assays, pharmacological manipulation (rapamycin, FK506)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct electrophysiology and binding assays with both WT and mutant CLIC2, single lab, two orthogonal methods\",\n      \"pmids\": [\"28851804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CLIC2 is secreted into the extracellular milieu from secretory granules. Secreted CLIC2 binds to MMP14 (membrane type-1 MMP) and inhibits its activity, leading to suppressed MMP2 activation, thereby potentially suppressing tumor cell invasion.\",\n      \"method\": \"Localization to secretory granules (fractionation/imaging implied), binding assay between CLIC2 and MMP14, MMP activity assay (as described in review citing primary data)\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — mechanistic claims come from a review citing primary data not directly accessible in this abstract; single set of observations, no independent replication reported\",\n      \"pmids\": [\"36230813\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CLIC2 deletion in THP-1 monocytic cells (CLIC2 knock-out) does not affect monocyte morphology but causes macrophages to display increased membrane protrusions, upregulated CD11b/CD11c/CD80/CD86 markers, altered cytokine secretion (elevated CCL8, reduced IL-1β, IL-6, OPG), and increased Shp1 phosphorylation with concomitant loss of Stat3 phosphorylation. CLIC2 was shown to interact with both Shp1 and Stat3, suggesting CLIC2 regulates monocyte-to-macrophage differentiation via the Stat3 signaling pathway.\",\n      \"method\": \"CRISPR/genetic knock-out (THP-1CLIC2_KO), flow cytometry, cytokine secretion profiling, phosphorylation western blot, protein interaction (CLIC2 with Shp1 and Stat3)\",\n      \"journal\": \"Biology direct\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic KO with multiple orthogonal readouts (morphology, markers, cytokines, signaling phosphorylation, interaction), single lab, single study, no independent replication\",\n      \"pmids\": [\"40696397\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CLIC2 is a GST-structural-family monomeric protein that, in its primary characterized role, acts as an inhibitor of ryanodine receptor (RyR1/RyR2) Ca2+ release channels by binding to the clamp-shaped region of RyR and stabilizing the closed state; this inhibition is redox-sensitive (inhibitory under oxidizing, activating under reducing conditions), and is abolished or converted to hyperactivation by the disease-causing H101Q mutation that causes a channelopathy with intellectual disability and cardiomegaly; additionally, CLIC2 can be secreted extracellularly to inhibit MMP14/MMP2, and intracellularly regulates macrophage differentiation through interactions with Shp1 and Stat3.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CLIC2 is a monomeric member of the GST structural family that functions principally as a regulator of intracellular Ca2+ release by binding and modulating ryanodine receptor channels [#1, #2, #4]. In its water-soluble form CLIC2 adopts a GST fold, and unlike CLIC1 it forms an intramolecular disulfide and remains monomeric across redox conditions; it forms pH-dependent chloride channels in vitro that are more active at low pH and subject to redox regulation [#2]. CLIC2 binds directly to the clamp-shaped region of RyR1 (between domains 5 and 6), inducing a conformational change, increasing ryanodine binding affinity, decreasing channel open probability by prolonging mean closed time, and reducing Ca2+ efflux from sarcoplasmic reticulum vesicles [#4]; it acts comparably on cardiac RyR2 [#1]. This modulation is redox-dependent, with CLIC2 inhibiting RyR2 under oxidizing conditions and activating it under reducing conditions, dependent on GSH:GSSG buffer on both luminal and cytoplasmic channel faces [#3]. CLIC2 also promotes sub-conductance RyR openings and reduces FKBP association with RyRs [#7]. The X-linked H101Q mutation converts CLIC2 from an RyR inhibitor into a gain-of-function activator that prolongs channel opening and amplifies Ca2+ signals, causing a channelopathy presenting with intellectual disability, atrial fibrillation, cardiomegaly, and seizures in affected males [#6]. Beyond its RyR role, lower-confidence findings place CLIC2 in extracellular MMP14/MMP2 inhibition [#8] and in macrophage differentiation via Shp1/Stat3 [#9].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Established the existence and genomic identity of CLIC2 as a candidate chloride channel gene, defining the molecular entity before any function was known.\",\n      \"evidence\": \"cDNA cloning, sequence alignment, and genomic structure determination mapping the gene to Xq28\",\n      \"pmids\": [\"9339381\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional or biochemical characterization of the protein\", \"Homology-based annotation only; channel activity unproven\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Answered what CLIC2 actually does by demonstrating it is an inhibitor of cardiac RyR2 Ca2+ release channels, shifting the protein from a presumed chloride channel to an RyR regulator.\",\n      \"evidence\": \"Lipid bilayer single-channel recording, SR vesicle Ca2+ efflux assay, and antibody reversal; enzyme activity assays showing low glutathione peroxidase but no thiol transferase activity\",\n      \"pmids\": [\"15147738\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RyR binding site not localized\", \"Redox dependence of the interaction not yet defined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved the structural basis of CLIC2, placing it in the GST structural family and explaining why it remains monomeric, while defining a candidate protein-recognition interface.\",\n      \"evidence\": \"1.8-Å X-ray crystallography in two crystal forms, site-directed mutagenesis, and in vitro channel recording\",\n      \"pmids\": [\"17945253\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The 'foot-in-mouth' interface as the RyR-binding site was inferred, not demonstrated\", \"Soluble-to-membrane transition mechanism unresolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed that CLIC2's effect on RyR is not fixed but redox-switched, establishing CLIC2 as a redox-sensitive bidirectional modulator.\",\n      \"evidence\": \"Lipid bilayer single-channel recording with controlled GSH:GSSG redox buffer on both channel faces\",\n      \"pmids\": [\"18522493\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single method\", \"Molecular identity of the redox sensor residues not mapped\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Pinpointed where and how CLIC2 binds RyR1, converting a functional inhibition into a structurally defined interaction with a measured conformational consequence.\",\n      \"evidence\": \"[3H]ryanodine binding, Ca2+ efflux assay, lipid bilayer single-channel recording, and cryo-EM localization to the clamp region between domains 5 and 6\",\n      \"pmids\": [\"19356589\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution contacts at the interface not resolved\", \"Whether the same site mediates RyR2 binding not directly tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Proposed a structural rationale for how the disease mutation H101Q alters CLIC2, framing it as a defect in conformational flexibility and membrane association.\",\n      \"evidence\": \"In silico molecular dynamics simulation and electrostatics calculations\",\n      \"pmids\": [\"21630357\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Computational prediction only, no experimental validation of the predicted structural effects\", \"Link to functional channel behavior not established at this stage\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Connected CLIC2 to human disease and established the mutation mechanism: H101Q is a gain-of-function variant that activates rather than inhibits RyR, causing an X-linked channelopathy.\",\n      \"evidence\": \"Exome sequencing for gene identification plus functional lipid bilayer electrophysiology of RyR channels with H101Q mutant protein\",\n      \"pmids\": [\"22814392\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How loss of H101 produces activation rather than simple loss of inhibition not fully mechanistically resolved\", \"Tissue-specific contributions to the multisystem phenotype unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Refined the mechanism by showing both WT and mutant CLIC2 promote sub-conductance RyR openings and displace FKBP, distinguishing how the same biophysical change yields opposite physiological outcomes.\",\n      \"evidence\": \"Lipid bilayer single-channel recording, FKBP-RyR binding assays, and pharmacological manipulation with rapamycin and FK506\",\n      \"pmids\": [\"28851804\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Physiological relevance of FKBP displacement in vivo not established\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Extended CLIC2 beyond intracellular Ca2+ signaling by reporting a secreted, extracellular role inhibiting MMP14 and downstream MMP2 activation.\",\n      \"evidence\": \"Secretory-granule localization, CLIC2–MMP14 binding assay, and MMP activity assay, as described in a review citing primary data\",\n      \"pmids\": [\"36230813\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanistic claims drawn from a review citing primary data, not independently replicated here\", \"Secretion mechanism and physiological context underdefined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified an intracellular signaling role in immune-cell differentiation, linking CLIC2 to Shp1/Stat3 control of monocyte-to-macrophage transition.\",\n      \"evidence\": \"CRISPR knock-out in THP-1 cells with flow cytometry, cytokine profiling, phosphorylation westerns, and CLIC2 interaction assays with Shp1 and Stat3\",\n      \"pmids\": [\"40696397\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single study, no independent replication\", \"Direct vs. indirect nature of Shp1/Stat3 interactions not resolved\", \"Relationship to the RyR/Ca2+ role unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CLIC2 transitions between its soluble GST-fold form, its membrane-inserted chloride-channel form, its RyR-bound regulatory form, and its secreted MMP-inhibitory form within a single cellular context remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying model linking the channel, RyR-modulator, secreted, and signaling roles\", \"Atomic structure of any CLIC2–partner complex unresolved\", \"Endogenous redox conditions governing inhibition vs. activation in vivo not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 3, 4]},\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RYR1\", \"RYR2\", \"MMP14\", \"PTPN6\", \"STAT3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}