{"gene":"GLRX3","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":2000,"finding":"PICOT (GLRX3) was identified as a PKCθ-interacting protein via yeast two-hybrid; its N-terminal thioredoxin homology domain is required for the interaction with PKC. Overexpression of full-length PICOT (but not N- or C-terminal fragments alone) inhibited JNK activation and AP-1/NF-κB transcription in T cells.","method":"Yeast two-hybrid, colocalization, transient overexpression with reporter assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — yeast two-hybrid plus functional overexpression assays in T cells, single lab, two complementary methods","pmids":["10636891"],"is_preprint":false},{"year":2006,"finding":"Yeast Grx3 and Grx4 interact with Aft1 both in vivo and in vitro, and their Grx domains are required for promoting Aft1 nuclear export; the grx3grx4 double mutant accumulates intracellular iron and constitutively activates Aft1 target genes.","method":"Co-immunoprecipitation, in vitro binding, GFP localization, genetic deletion analysis","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal in vivo/in vitro interaction assays plus genetic epistasis, single lab","pmids":["17074835"],"is_preprint":false},{"year":2006,"finding":"PICOT (GLRX3) overexpression in cardiomyocytes blocked hypertrophic responses to endothelin-1 and phenylephrine; transgenic mice with cardiac-specific PICOT overexpression showed increased ventricular function and cardiomyocyte contractility associated with increased myofilament Ca2+ responsiveness and enhanced SERCA Ca2+ reuptake.","method":"Adenoviral gene transfer, transgenic mouse model, cardiomyocyte contractility assays, Ca2+ handling analysis","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal in vitro and in vivo methods with physiological readouts, replicated in multiple experimental systems","pmids":["16809552"],"is_preprint":false},{"year":2008,"finding":"PICOT directly interacts with muscle LIM protein (MLP) via its C-terminal half (PICOT-C), colocalizes with MLP at the Z-disc, and disrupts MLP-calcineurin interaction in a dose-dependent manner, thereby abrogating calcineurin-NFAT signaling and inhibiting cardiac hypertrophy.","method":"GST pull-down, mass spectrometry, coimmunoprecipitation, immunofluorescence, reporter assays, transgenic mouse pressure overload model","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — GST pull-down/MS identification confirmed by reciprocal Co-IP, functional validation in cells and transgenic mice with multiple readouts","pmids":["18258855"],"is_preprint":false},{"year":2008,"finding":"PICOT(+/-) mice show exacerbated pressure-overload cardiac hypertrophy with enhanced calcineurin-NFAT signaling, reduced cardiomyocyte contractility, hypophosphorylation of phospholamban, and reduced SERCA activity, confirming PICOT as a negative regulator of cardiac hypertrophy and a positive inotropic regulator in vivo.","method":"Gene trap knockout mouse, pressure overload model, signaling assays, contractility measurements","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with multiple defined phenotypic readouts, confirmed physiological relevance of calcineurin-NFAT and SERCA pathway effects","pmids":["18929570"],"is_preprint":false},{"year":2009,"finding":"Yeast Grx3 and Grx4, upon coexpression with Fra2 (BolA homologue), form a [2Fe-2S]-bridged heterodimeric complex; the cluster is coordinated by the active site cysteine of Grx3/4, glutathione, and a histidine residue from Fra2. Without Fra2, Grx3/4 forms a [2Fe-2S]-bridged homodimer. This complex can serve as a signal to control the iron regulon.","method":"Reconstitution in E. coli, UV-visible absorption/CD, resonance Raman, EPR, ENDOR, Mossbauer, EXAFS spectroscopy, mutagenesis","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution plus comprehensive multi-spectroscopic characterization plus mutagenesis, rigorous single study","pmids":["19715344"],"is_preprint":false},{"year":2009,"finding":"Fission yeast Grx4 physically interacts with Crm1 (exportin) and with the iron regulatory protein Php4; deletion of grx4 renders Php4 constitutively nuclear and active. Grx4 and Crm1 are required for iron-dependent nuclear export of Php4.","method":"Co-immunoprecipitation, bimolecular fluorescence complementation (BiFC), two-hybrid assays, leptomycin B treatment, GFP imaging","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal interaction assays (Co-IP, BiFC, Y2H) with genetic and pharmacological validation in living cells","pmids":["19502236"],"is_preprint":false},{"year":2010,"finding":"Human GLRX3 (PICOT) binds two bridging [2Fe-2S]2+ clusters in a homodimeric complex, coordinated by active site cysteinyl residues of its two Grx domains and non-covalently bound glutathione. The [2Fe-2S]2+ clusters are lost upon treatment with ferricyanide or S-nitroso glutathione, suggesting redox-induced cluster dissociation as a potential activation mechanism. Co-immunoprecipitation of 55-iron confirmed iron binding under physiological conditions.","method":"UV-visible spectroscopy, CD, EPR, 55Fe co-immunoprecipitation, treatment with oxidants","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro spectroscopic reconstitution plus cellular 55Fe co-IP, single lab but multiple orthogonal methods","pmids":["20226171"],"is_preprint":false},{"year":2011,"finding":"S. pombe Grx4 is required for iron-dependent inhibition of Fep1 transcription factor under low-iron conditions. Grx4's TRX domain interacts strongly and constitutively with Fep1's C-terminal region (requiring Cys35), while the GRX domain interacts weakly and iron-dependently with Fep1's N-terminal region (requiring Cys172).","method":"Deletion mapping, co-immunoprecipitation, yeast genetics, chromatin binding assays","journal":"Eukaryotic cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — domain-mapping mutagenesis combined with in vivo Co-IP and transcriptional assays, defining specific residues and interaction surfaces","pmids":["21421748"],"is_preprint":false},{"year":2011,"finding":"S. cerevisiae Grx3/Grx4 and Fe-S cluster protein Dre2 contribute to in vivo diferric tyrosyl radical (Fe2(III)-Tyr•) cofactor assembly in ribonucleotide reductase subunit Rnr2; growth defects of rnr4 mutants are enhanced by grx3/grx4 deficiency, placing Grx3/4 in the pathway of iron loading into Rnr2.","method":"Genetic epistasis, EPR-based Tyr• measurement, iron loading assays, spheroplast complementation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with biochemical readouts, single lab","pmids":["21931161"],"is_preprint":false},{"year":2011,"finding":"Mouse Grx3 knockout results in embryonic lethality at E12.5; Grx3-deficient MEFs and HeLa knockdown cells show impaired cell cycle progression at G2/M with increased binucleated cells, establishing a direct role in mitotic exit.","method":"Knockout mouse (embryonic lethal), flow cytometry cell cycle analysis, siRNA knockdown, immunofluorescence","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with embryonic lethal phenotype plus cell cycle readouts in two cellular systems","pmids":["21575136"],"is_preprint":false},{"year":2011,"finding":"PICOT (GLRX3) physically interacts with anamorsin (CIAPIN1/AM) via the N-terminal regions of both proteins; inhibition of this interaction impairs cell growth.","method":"Yeast two-hybrid, co-immunoprecipitation, cell growth assays","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single yeast two-hybrid plus Co-IP, limited mechanistic follow-up","pmids":["21513700"],"is_preprint":false},{"year":2011,"finding":"Fission yeast Grx4 physically interacts with Fep1 in vivo, and mutation of Cys172 (active site of GRX domain) abolishes iron-dependent gene regulation and the Grx4-Fep1 interaction detected by BiFC, indicating that Fe-S cofactor binding in the GRX domain is critical for Fep1 modulation.","method":"Co-immunoprecipitation, BiFC, site-directed mutagenesis, transcription assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple interaction assays with mutagenesis, single lab","pmids":["21531205"],"is_preprint":false},{"year":2012,"finding":"PICOT directly binds the catalytic domain of PKCζ via its N-terminal thioredoxin-like domain; purified PICOT inhibits PKCζ kinase activity in vitro. PICOT-mediated PKCζ inhibition down-regulates PKCα and PP2A activities, leading to increased phosphorylation of phospholamban (PLB) and troponin I/T, enhancing SERCA2a activity and cardiomyocyte contractility.","method":"Protein pull-down, in vitro kinase assay, PKCζ inhibitor peptide, AAV-mediated overexpression, cardiomyocyte contractility measurements","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro kinase reconstitution plus multiple cellular and in vivo experiments with defined downstream pathway","pmids":["22449794"],"is_preprint":false},{"year":2013,"finding":"PICOT is a caspase-3 cleavage substrate; in vitro cleavage assays show specific cleavage at DRLD(101)/G and EELD(226)/T. Endogenous PICOT is cleaved by caspase-3 during staurosporine- and etoposide-induced apoptosis. PICOT overexpression (WT or cleavage-resistant D101A/D226A) accelerates etoposide-induced caspase-3 activation, while PICOT knockdown blocks it.","method":"In vitro caspase cleavage assay, site-directed mutagenesis, pan-caspase inhibitor treatment, siRNA knockdown","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro reconstituted cleavage assay plus mutagenesis plus cellular validation, single lab with orthogonal approaches","pmids":["23415866"],"is_preprint":false},{"year":2013,"finding":"Zebrafish depletion of Grx3 severely impairs hemoglobin maturation. Silencing human GLRX3 in HeLa cells decreases activities of cytosolic Fe/S proteins including iron regulatory protein 1 (IRP1), leading to decreased ferritin and increased transferrin receptor levels, a signature of cellular iron starvation despite unimpaired iron uptake.","method":"Zebrafish morpholino knockdown, siRNA in HeLa cells, enzyme activity assays, Western blot for IRP1/ferritin/transferrin receptor","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent model systems (zebrafish and human cells) with defined biochemical readouts of Fe/S protein activity and iron metabolism","pmids":["23615448"],"is_preprint":false},{"year":2015,"finding":"Human GRX3 and apo BOLA2 form a heterotrimeric complex (two BOLA2 molecules + one GRX3 molecule) that binds two [2Fe-2S]2+ clusters, each bridged between one BOLA2 and one GRX3 Grx domain; this complex transfers both [2Fe-2S]2+ clusters to apo anamorsin to produce its mature holo form, establishing GRX3-BOLA2 as a [2Fe-2S] cluster transfer component in cytosolic Fe/S protein maturation.","method":"NMR spectroscopy, UV-visible/CD spectroscopy, in vitro reconstitution and cluster transfer assays","journal":"Journal of the American Chemical Society","confidence":"High","confidence_rationale":"Tier 1 / Strong — atomic-level NMR characterization plus in vitro reconstitution of cluster transfer, rigorous single study with multiple methods","pmids":["26613676"],"is_preprint":false},{"year":2016,"finding":"Yeast Grx3/4 physically interact with Sir2 sirtuin in vivo and can reverse S-glutathionylation of Sir2 (at cysteines in the catalytic domain) in vitro and in vivo, restoring Sir2 deacetylase activity after disulfide stress; this establishes Grx3/4 as Sir2 thiol-reductases that regulate telomeric silencing via S-deglutathionylation.","method":"In vitro deglutathionylation assay, in vivo S-glutathionylation detection, co-immunoprecipitation, site-directed mutagenesis, silencing assay","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — in vitro assay plus in vivo validation with mutagenesis, single lab","pmids":["27085841"],"is_preprint":false},{"year":2016,"finding":"Yeast Grx3 and Grx4 physically interact with the MAPK Slt2 in vivo and in vitro, forming Fe/S-bridged complexes where cysteines of Grx3/4 active sites, glutathione, and specific Slt2 cysteines provide ligands. Loss of Grx3/4 impairs Slt2 phosphorylation and Rlm1 transcription upon oxidative stress; Grx4 is the predominant regulator of Slt2 phosphorylation under oxidative conditions.","method":"Co-immunoprecipitation (in vivo and in vitro), spectroscopic analysis, mutagenesis, viability and kinase activity assays","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus functional epistasis plus mutagenesis, single lab","pmids":["28007574"],"is_preprint":false},{"year":2017,"finding":"S. pombe Grx4 and its partner Fra2 form a [2Fe-2S]-bridged heterodimer with specific spectroscopic properties; conserved cysteines in Grx4 (Cys172) and Php4 (Cys221, Cys227) are necessary for Fe-S cluster binding and stable Grx4-Php4 complex formation. Grx4 controls Php4 function through binding of a bridging [2Fe-2S] cluster.","method":"UV-visible/CD/EPR spectroscopy, in vitro reconstitution, mutagenesis, size exclusion chromatography, in vitro titration","journal":"Metallomics","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with multi-spectroscopic characterization plus mutagenesis, single lab","pmids":["28725905"],"is_preprint":false},{"year":2018,"finding":"Crystal structures of the Trx domain (Grx3Trx) and Grx domain (Grx3Grx) of yeast Grx3 were solved; structural analyses revealed that the Trx domain contributes to glutathione S-transferase activity via an inter-domain disulfide between Cys37 and Cys176. NMR titration, pull-down, and SPR assays showed that Fra2 forms a noncovalent heterodimer with Grx3 via an interface between Fra2's helix-turn-helix motif and Grx3Grx's C-terminal segment, independent of the Fe-S-covalent heterodimer.","method":"X-ray crystallography, NMR spectroscopy, GST pull-down, surface plasmon resonance, activity assays","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus NMR titration plus SPR in a single study with functional assays","pmids":["29524511"],"is_preprint":false},{"year":2018,"finding":"PICOT interacts with EED (a PRC2 core component) via each of its two C-terminal PICOT/Grx homology domains; PICOT and EED co-immunoprecipitate from Jurkat T cell nuclear extracts and partially colocalize in nuclei. PICOT knockdown reduces H3K27me3 at the MYT1 gene promoter, indicating PICOT modulates PRC2-dependent chromatin silencing.","method":"Yeast two-hybrid, GST pull-down, reciprocal coimmunoprecipitation, immunofluorescence/confocal microscopy, ChIP (H3K27me3)","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus domain mapping pull-down plus ChIP, single lab","pmids":["30595380"],"is_preprint":false},{"year":2019,"finding":"The conserved CDC motif cysteines of yeast Aft2 are essential for [2Fe-2S] cluster binding and Aft2 dimerization, and one of the two cysteines is required for interaction with the [2Fe-2S]-Grx3-Bol2 (Bol2=Fra2 homolog) complex; cluster transfer from Grx3-Bol2 to Aft2 likely occurs through a ligand exchange mechanism.","method":"Size exclusion chromatography, circular dichroism spectroscopy, mutagenesis, in vitro cluster transfer assays","journal":"Journal of biological inorganic chemistry","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — in vitro reconstitution/spectroscopy plus mutagenesis, single lab","pmids":["31493153"],"is_preprint":false},{"year":2019,"finding":"PICOT-deficient Jurkat T cells show impaired γH2AX foci formation and reduced phosphorylation of ATR, Chk1, and Chk2 in response to genotoxic drugs and radiation; partial localization of PICOT at γH2AX foci at DNA double-strand break sites was observed. PICOT acts as a positive upstream regulator of ATR-dependent DNA damage signaling, independent of ROS levels.","method":"siRNA knockdown, immunofluorescence/confocal microscopy, flow cytometry, Western blot for phospho-ATR/Chk1/Chk2/γH2AX","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with multiple defined signaling readouts and localization data, single lab","pmids":["31176019"],"is_preprint":false},{"year":2019,"finding":"PICOT knockdown in Jurkat T cells reduces H3K27me3 at the CCND2 gene promoter, decreases EED and EZH2 occupancy at CCND2, and leads to increased CCND2 (cyclin D2) mRNA and protein expression, establishing PICOT binding to chromatin-associated EED as a modulator of PRC2-mediated repression of CCND2.","method":"Coimmunoprecipitation, ChIP (H3K27me3, EED, EZH2), siRNA knockdown, RT-PCR, Western blot","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple ChIP targets with Co-IP and expression readouts confirming mechanistic link, single lab","pmids":["31527584"],"is_preprint":false},{"year":2020,"finding":"Human GLRX3 transfers its [2Fe-2S]2+ clusters to monomeric apo NUBP1 (CIA machinery component); in the presence of glutathione as reductant, the clusters are reductively coupled to form [4Fe-4S]2+ clusters on both N-terminal (CX13CX2CX5C) and C-terminal (CPXC) motifs of NUBP1. Cluster binding at the C-terminal motif promotes NUBP1 dimerization; GLRX3 acts as a [2Fe-2S] cluster chaperone in the early CIA pathway.","method":"In vitro reconstitution, UV-visible/CD/EPR spectroscopy, size exclusion chromatography, cluster transfer assays","journal":"Journal of the American Chemical Society","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of cluster transfer plus multi-spectroscopic characterization of products, single lab rigorous study","pmids":["32429669"],"is_preprint":false},{"year":2020,"finding":"Human GLRX3 (PICOT) interacts with human GMP synthase (hGMPs) via conserved residues that bridge Fe/S clusters and glutathione; this interaction downregulates the Gcn2/ISR stress pathway. The interaction and pathway function are conserved in yeast (Grx3/Grx4 with GUA1/ScGMPs) and human GLRX3/hGMPs can functionally complement yeast Grx3/Grx4.","method":"Yeast humanization complementation, two-hybrid, co-expression, genetic pathway assays (Gcn2 readouts)","journal":"Applied and environmental microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic complementation plus interaction assays across two organisms, single lab","pmids":["32414791"],"is_preprint":false},{"year":2023,"finding":"S. pombe Grx4-Fra2 heterodimer facilitates [2Fe-2S] cluster removal from the Fep1 transcription repressor via unidirectional cluster transfer from Fep1 to Grx4-Fra2 in the presence of GSH; Fra2 His66 and Cys29 serve as Fe-S cluster ligands in the Grx4-Fra2 complex. This defines the Fe-S cluster-dependent mechanism of Fep1 inactivation under low iron.","method":"In vitro reconstitution, CD spectroscopy, mutagenesis, in vivo transcription assays, growth assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstituted cluster transfer plus spectroscopy plus mutagenesis plus in vivo validation, single lab rigorous study","pmids":["37923140"],"is_preprint":false},{"year":2025,"finding":"In HeLa cells with CRISPR/Cas9 GLRX3 knockout, IRP1 is activated (indicating iron starvation due to impaired iron metabolism). Rescue experiments show that only a Trx-GrxA construct (first Trx-like domain + first Grx domain) restores the phenotype to wild-type levels; the individual domains alone are insufficient, and the second Grx domain (GrxB) is not required for this function.","method":"CRISPR/Cas9 knockout, domain rescue transfection, IRP1 activity assay","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with defined molecular readout and systematic domain rescue, single lab","pmids":["40400140"],"is_preprint":false},{"year":2026,"finding":"In satellite glial cells of aged mice, GLRX3 upregulation catalyzes deglutathionylation of HMGB1 at Cys106 via its catalytic Cys148 residue; this converts HMGB1 into a TLR4-MD2 agonist, triggering neuronal NF-κB signaling and upregulation of TRPA1 and TRPV2 channels in nociceptors, sustaining neuropathic pain. Satellite glial cell-targeted knockdown of GLRX3 restored HMGB1 glutathionylation and reversed pain phenotype in aged mice.","method":"Single-nucleus RNA sequencing, redox proteomics, site-directed mutagenesis (Cys148), in vivo knockdown, behavioral pain assays, TLR4 signaling assays","journal":"Brain","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic mutagenesis with in vivo knockdown and multiple pathway readouts, single lab, not yet replicated","pmids":["42007893"],"is_preprint":false}],"current_model":"GLRX3 (PICOT) is a multidomain cytosolic monothiol glutaredoxin that coordinates [2Fe-2S] clusters via its CGFS-motif Grx domains and glutathione; it functions as an iron-sulfur cluster chaperone transferring [2Fe-2S] clusters to BOLA2-anamorsin and NUBP1 (CIA machinery), thereby supporting cytosolic Fe/S protein maturation and iron homeostasis. In the nucleus it binds EED/PRC2 to regulate H3K27me3 at target gene promoters. In cardiac tissue, PICOT inhibits hypertrophy by disrupting the MLP-calcineurin interaction to suppress NFAT signaling, and enhances contractility by inhibiting PKCζ, which in turn reduces PKCα and PP2A activities and increases PLB/troponin phosphorylation and SERCA2a activity. PICOT is also a caspase-3 substrate and a positive regulator of ATR-dependent DNA damage signaling, and in aged satellite glial cells GLRX3 deglutathionylates HMGB1 at Cys106 to activate TLR4-mediated nociceptor sensitization."},"narrative":{"mechanistic_narrative":"GLRX3 (PICOT) is a multidomain monothiol glutaredoxin that functions as a [2Fe-2S] cluster chaperone in the cytosolic iron-sulfur cluster assembly (CIA) pathway and as a regulator of cytosolic Fe/S protein maturation and iron homeostasis [PMID:23615448, PMID:26613676]. Its Grx domains coordinate bridging [2Fe-2S]2+ clusters together with non-covalently bound glutathione, forming homodimers or, with BOLA2, a heterotrimeric complex that delivers clusters to apo-anamorsin (CIAPIN1) and to NUBP1, where reductive coupling generates [4Fe-4S] clusters [PMID:20226171, PMID:26613676, PMID:32429669]; depletion of GLRX3 produces a cellular iron-starvation signature with activated IRP1, reduced ferritin, and impaired hemoglobin maturation, and a single Trx-Grx unit is sufficient to restore this function [PMID:23615448, PMID:40400140]. Loss of Grx3 causes embryonic lethality and a G2/M cell-cycle defect with binucleation, linking Fe/S delivery to mitotic exit [PMID:21575136]. The conserved cluster-transfer and iron-regulatory role is recapitulated in yeast, where Grx3/Grx4 form [2Fe-2S]-bridged complexes with BolA homologues (Fra2/Bol2) and govern iron-responsive transcription factors (Aft1/Aft2, Php4, Fep1) through cluster-dependent control of their nuclear export and DNA binding [PMID:17074835, PMID:19715344, PMID:31493153, PMID:37923140]. In cardiac tissue PICOT acts as a negative regulator of hypertrophy and a positive inotropic factor: it binds muscle LIM protein at the Z-disc to disrupt the MLP-calcineurin interaction and suppress calcineurin-NFAT signaling [PMID:18258855, PMID:18929570], and binds the catalytic domain of PKCζ to inhibit its kinase activity, down-regulating PKCα and PP2A to increase phospholamban/troponin phosphorylation and SERCA2a-driven contractility [PMID:22449794]. In the nucleus PICOT binds the PRC2 component EED via its C-terminal Grx domains to modulate H3K27me3 at target promoters including MYT1 and CCND2 [PMID:30595380, PMID:31527584]. PICOT additionally serves as a caspase-3 substrate that promotes apoptotic caspase-3 activation [PMID:23415866] and as a positive upstream regulator of ATR-dependent DNA-damage signaling [PMID:31176019]. In aged satellite glial cells GLRX3 deglutathionylates HMGB1 at Cys106 through its catalytic Cys148, converting HMGB1 into a TLR4-MD2 agonist that sensitizes nociceptors [PMID:42007893].","teleology":[{"year":2000,"claim":"Established the first molecular partner and a candidate signaling role by showing PICOT interacts with PKC and dampens stress-kinase/transcription-factor output in T cells.","evidence":"Yeast two-hybrid and overexpression reporter assays in T cells","pmids":["10636891"],"confidence":"Medium","gaps":["No biochemical demonstration of direct kinase regulation at this stage","Iron-sulfur/glutaredoxin function not yet recognized"]},{"year":2006,"claim":"Defined the cardiac function of PICOT as an anti-hypertrophic, positive-inotropic factor acting through Ca2+ handling.","evidence":"Adenoviral transfer, cardiac-specific transgenic mice, contractility and Ca2+ handling assays","pmids":["16809552"],"confidence":"High","gaps":["Molecular target mediating the anti-hypertrophic effect unidentified","Mechanism for enhanced SERCA reuptake undefined"]},{"year":2006,"claim":"Connected GLRX3 orthologs to iron homeostasis by showing yeast Grx3/Grx4 control nuclear export of the iron-regulatory factor Aft1.","evidence":"Co-IP, in vitro binding, GFP localization, deletion genetics in S. cerevisiae","pmids":["17074835"],"confidence":"Medium","gaps":["Chemical basis of iron sensing not established","Relevance to human GLRX3 not yet shown"]},{"year":2008,"claim":"Identified the molecular mechanism of cardiac anti-hypertrophy: PICOT binds MLP at the Z-disc and competitively disrupts MLP-calcineurin signaling to NFAT.","evidence":"GST pull-down/MS, reciprocal Co-IP, immunofluorescence, pressure-overload transgenic and PICOT(+/-) mice","pmids":["18258855","18929570"],"confidence":"High","gaps":["Whether glutaredoxin/Fe-S activity contributes to the cardiac role unknown","Stoichiometry of MLP-calcineurin displacement not resolved"]},{"year":2009,"claim":"Provided the chemical basis for iron sensing, demonstrating Grx3/4 bind bridging [2Fe-2S] clusters as homodimers or as Fra2 (BolA) heterodimers coordinated by active-site cysteine, glutathione, and a Fra2 histidine.","evidence":"E. coli reconstitution with multi-spectroscopic characterization and mutagenesis; Co-IP/BiFC/Y2H for Crm1 and Php4 in fission yeast","pmids":["19715344","19502236"],"confidence":"High","gaps":["Direction of cluster trafficking (sensing vs. delivery) not yet defined","Human protein cluster coordination not yet confirmed"]},{"year":2010,"claim":"Confirmed that human GLRX3 binds two bridging [2Fe-2S] clusters via its Grx domains and glutathione, with oxidant-induced cluster loss as a candidate switch.","evidence":"UV-vis/CD/EPR spectroscopy and 55Fe co-IP of human GLRX3","pmids":["20226171"],"confidence":"High","gaps":["Physiological recipients of the clusters not identified","In vivo significance of redox-induced cluster dissociation untested"]},{"year":2011,"claim":"Linked GLRX3 to cytosolic Fe/S maturation and cell division by establishing essential roles in mitotic exit and a physical link to anamorsin.","evidence":"Embryonic-lethal Grx3 knockout mouse, cell-cycle flow cytometry, siRNA in HeLa; yeast genetic epistasis with Dre2/Rnr; Y2H/Co-IP with anamorsin","pmids":["21575136","21931161","21513700"],"confidence":"High","gaps":["Mechanistic basis of G2/M arrest not defined","Anamorsin interaction lacked reciprocal/biochemical depth at this stage"]},{"year":2011,"claim":"Resolved how the Grx domain controls an iron-responsive repressor, mapping Trx- and Grx-domain interactions and the requirement of Grx Cys172/Fe-S binding for Fep1 regulation.","evidence":"Domain mapping, Co-IP, BiFC, site-directed mutagenesis and transcription assays in S. pombe","pmids":["21421748","21531205"],"confidence":"High","gaps":["Cluster transfer chemistry to/from Fep1 not yet demonstrated"]},{"year":2013,"claim":"Demonstrated that human GLRX3 is required for cytosolic Fe/S protein activity and organismal iron handling, producing an iron-starvation signature when depleted.","evidence":"Zebrafish morpholino, HeLa siRNA, IRP1/ferritin/transferrin-receptor readouts and Fe/S enzyme assays","pmids":["23615448"],"confidence":"High","gaps":["Direct cluster recipients in human cells not yet identified","Distinction between chaperone vs. signaling role unresolved"]},{"year":2013,"claim":"Defined the biochemical link from PICOT to cardiac contractility and identified PICOT as a caspase-3 substrate that promotes apoptosis.","evidence":"In vitro kinase assays/pull-down for PKCζ with AAV overexpression and contractility; in vitro caspase cleavage assays with cleavage-resistant mutants and knockdown","pmids":["22449794","23415866"],"confidence":"High","gaps":["Whether Fe-S/glutaredoxin activity contributes to PKCζ inhibition unknown","Functional consequence of PICOT cleavage fragments undefined"]},{"year":2015,"claim":"Established GLRX3 as a [2Fe-2S] cluster transfer agent in the CIA pathway by showing a GRX3-BOLA2 heterotrimer delivers clusters to apo-anamorsin.","evidence":"NMR and UV-vis/CD spectroscopy with in vitro reconstitution and cluster transfer assays","pmids":["26613676"],"confidence":"High","gaps":["Source of clusters delivered to GRX3-BOLA2 not defined","Regulation of transfer directionality unaddressed"]},{"year":2016,"claim":"Expanded the glutaredoxin enzymatic repertoire, showing Grx3/4 deglutathionylate Sir2 and form Fe-S-bridged complexes with the MAPK Slt2 to regulate oxidative-stress signaling.","evidence":"In vitro/in vivo deglutathionylation, Co-IP, spectroscopy and mutagenesis in yeast","pmids":["27085841","28007574"],"confidence":"Medium","gaps":["Human relevance of Sir2/Slt2 regulation not tested","Single-lab findings without independent replication"]},{"year":2018,"claim":"Provided structural and chromatin-regulatory mechanism, solving Grx3 Trx/Grx domain structures and defining a non-covalent Fra2-Grx3 interface, and linking PICOT to PRC2 via EED.","evidence":"X-ray crystallography, NMR titration, SPR and activity assays (yeast); Y2H, GST pull-down, reciprocal Co-IP and H3K27me3 ChIP (human)","pmids":["29524511","30595380"],"confidence":"High","gaps":["Functional impact of the non-covalent vs. covalent Fra2-Grx3 interfaces unresolved","How PICOT alters PRC2 catalysis mechanistically unknown"]},{"year":2019,"claim":"Detailed the cluster-dependent mechanism of iron-regulator inactivation and added nuclear and DNA-damage roles for PICOT.","evidence":"In vitro reconstitution/CD with mutagenesis (Php4/Aft2); siRNA with phospho-ATR/Chk1/Chk2/γH2AX readouts and ChIP for CCND2 (human)","pmids":["28725905","31493153","31176019","31527584"],"confidence":"Medium","gaps":["Mechanism by which PICOT promotes ATR activation undefined","Whether DNA-damage and chromatin roles depend on Fe-S binding untested"]},{"year":2020,"claim":"Established GLRX3 as an early-CIA cluster chaperone for NUBP1 and connected it to nucleotide-metabolism stress signaling via GMP synthase.","evidence":"In vitro reconstitution/spectroscopy of NUBP1 cluster transfer; yeast humanization complementation and interaction assays for GMP synthase","pmids":["32429669","32414791"],"confidence":"High","gaps":["In-cell hierarchy among GLRX3 recipients (anamorsin, NUBP1) not defined","Physiological control of [2Fe-2S]→[4Fe-4S] coupling unknown"]},{"year":2023,"claim":"Resolved the directionality of cluster trafficking in iron sensing, showing unidirectional [2Fe-2S] removal from Fep1 by the Grx4-Fra2 heterodimer.","evidence":"In vitro reconstitution, CD spectroscopy, mutagenesis and in vivo transcription/growth assays in S. pombe","pmids":["37923140"],"confidence":"High","gaps":["Whether human GLRX3 performs analogous extraction from a target unknown"]},{"year":2025,"claim":"Mapped the minimal functional unit for human iron metabolism, showing a single Trx-Grx domain pair is sufficient to rescue the iron-starvation phenotype.","evidence":"CRISPR/Cas9 GLRX3 knockout with systematic domain-rescue and IRP1 activity readout in HeLa","pmids":["40400140"],"confidence":"Medium","gaps":["Role of the second Grx domain in other functions not addressed","Quantitative cluster occupancy of rescue constructs not measured"]},{"year":2026,"claim":"Defined a glutaredoxin catalytic role in disease, showing GLRX3 deglutathionylates HMGB1 to generate a TLR4 agonist that drives nociceptor sensitization in aged mice.","evidence":"snRNA-seq, redox proteomics, Cys148 mutagenesis, in vivo glial knockdown and behavioral pain assays","pmids":["42007893"],"confidence":"Medium","gaps":["Single-lab finding not independently replicated","Whether Fe-S binding modulates the deglutathionylase activity in this context untested"]},{"year":null,"claim":"How GLRX3's distinct activities — Fe/S cluster chaperone, cardiac signaling regulator, PRC2 modulator, DNA-damage signaling, and substrate deglutathionylase — are coordinated within one cell, and whether each depends on its iron-sulfur cluster, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No integrated model linking Fe/S chaperone activity to the cardiac, chromatin, and nociceptive roles","Upstream cluster donor to human GLRX3 not identified","Regulatory switch controlling which function dominates in a given tissue unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[17,29]},{"term_id":"GO:0140104","term_label":"molecular carrier activity","supporting_discovery_ids":[7,16,25]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,13]},{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[17,29]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[7,15,16]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[21,24]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[15,16,25]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[21,24]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[10]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,13]}],"complexes":["GRX3-BOLA2 [2Fe-2S] heterotrimer","PRC2 (via EED)"],"partners":["BOLA2","CIAPIN1","NUBP1","MLP","PRKCZ","EED","HMGB1","GMPS"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O76003","full_name":"Glutaredoxin-3","aliases":["PKC-interacting cousin of thioredoxin","PICOT","PKC-theta-interacting protein","PKCq-interacting protein","Thioredoxin-like protein 2"],"length_aa":335,"mass_kda":37.4,"function":"Together with BOLA2, acts as a cytosolic iron-sulfur (Fe-S) cluster assembly factor that facilitates [2Fe-2S] cluster insertion into a subset of cytosolic proteins (PubMed:26613676, PubMed:27519415). Acts as a critical negative regulator of cardiac hypertrophy and a positive inotropic regulator (By similarity). Required for hemoglobin maturation (PubMed:23615448). Does not possess any thyoredoxin activity since it lacks the conserved motif that is essential for catalytic activity","subcellular_location":"Cytoplasm, cytosol; Cytoplasm, cell cortex; Cytoplasm, myofibril, sarcomere, Z line","url":"https://www.uniprot.org/uniprotkb/O76003/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GLRX3","classification":"Not 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Grx3.","date":"2025","source":"ACS omega","url":"https://pubmed.ncbi.nlm.nih.gov/40521461","citation_count":0,"is_preprint":false},{"pmid":"41935503","id":"PMC_41935503","title":"Functional significance of highly conserved residues in dithiol glutaredoxin (Grx3) of cyanobacterium Synechococcus elongatus PCC 7942.","date":"2026","source":"Computational biology and chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41935503","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":31913,"output_tokens":7805,"usd":0.106407,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":17138,"output_tokens":5917,"usd":0.116807,"stage2_stop_reason":"end_turn"},"total_usd":0.223214,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"PICOT (GLRX3) was identified as a PKCθ-interacting protein via yeast two-hybrid; its N-terminal thioredoxin homology domain is required for the interaction with PKC. Overexpression of full-length PICOT (but not N- or C-terminal fragments alone) inhibited JNK activation and AP-1/NF-κB transcription in T cells.\",\n      \"method\": \"Yeast two-hybrid, colocalization, transient overexpression with reporter assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — yeast two-hybrid plus functional overexpression assays in T cells, single lab, two complementary methods\",\n      \"pmids\": [\"10636891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Yeast Grx3 and Grx4 interact with Aft1 both in vivo and in vitro, and their Grx domains are required for promoting Aft1 nuclear export; the grx3grx4 double mutant accumulates intracellular iron and constitutively activates Aft1 target genes.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding, GFP localization, genetic deletion analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal in vivo/in vitro interaction assays plus genetic epistasis, single lab\",\n      \"pmids\": [\"17074835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PICOT (GLRX3) overexpression in cardiomyocytes blocked hypertrophic responses to endothelin-1 and phenylephrine; transgenic mice with cardiac-specific PICOT overexpression showed increased ventricular function and cardiomyocyte contractility associated with increased myofilament Ca2+ responsiveness and enhanced SERCA Ca2+ reuptake.\",\n      \"method\": \"Adenoviral gene transfer, transgenic mouse model, cardiomyocyte contractility assays, Ca2+ handling analysis\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal in vitro and in vivo methods with physiological readouts, replicated in multiple experimental systems\",\n      \"pmids\": [\"16809552\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PICOT directly interacts with muscle LIM protein (MLP) via its C-terminal half (PICOT-C), colocalizes with MLP at the Z-disc, and disrupts MLP-calcineurin interaction in a dose-dependent manner, thereby abrogating calcineurin-NFAT signaling and inhibiting cardiac hypertrophy.\",\n      \"method\": \"GST pull-down, mass spectrometry, coimmunoprecipitation, immunofluorescence, reporter assays, transgenic mouse pressure overload model\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — GST pull-down/MS identification confirmed by reciprocal Co-IP, functional validation in cells and transgenic mice with multiple readouts\",\n      \"pmids\": [\"18258855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PICOT(+/-) mice show exacerbated pressure-overload cardiac hypertrophy with enhanced calcineurin-NFAT signaling, reduced cardiomyocyte contractility, hypophosphorylation of phospholamban, and reduced SERCA activity, confirming PICOT as a negative regulator of cardiac hypertrophy and a positive inotropic regulator in vivo.\",\n      \"method\": \"Gene trap knockout mouse, pressure overload model, signaling assays, contractility measurements\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with multiple defined phenotypic readouts, confirmed physiological relevance of calcineurin-NFAT and SERCA pathway effects\",\n      \"pmids\": [\"18929570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Yeast Grx3 and Grx4, upon coexpression with Fra2 (BolA homologue), form a [2Fe-2S]-bridged heterodimeric complex; the cluster is coordinated by the active site cysteine of Grx3/4, glutathione, and a histidine residue from Fra2. Without Fra2, Grx3/4 forms a [2Fe-2S]-bridged homodimer. This complex can serve as a signal to control the iron regulon.\",\n      \"method\": \"Reconstitution in E. coli, UV-visible absorption/CD, resonance Raman, EPR, ENDOR, Mossbauer, EXAFS spectroscopy, mutagenesis\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution plus comprehensive multi-spectroscopic characterization plus mutagenesis, rigorous single study\",\n      \"pmids\": [\"19715344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Fission yeast Grx4 physically interacts with Crm1 (exportin) and with the iron regulatory protein Php4; deletion of grx4 renders Php4 constitutively nuclear and active. Grx4 and Crm1 are required for iron-dependent nuclear export of Php4.\",\n      \"method\": \"Co-immunoprecipitation, bimolecular fluorescence complementation (BiFC), two-hybrid assays, leptomycin B treatment, GFP imaging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal interaction assays (Co-IP, BiFC, Y2H) with genetic and pharmacological validation in living cells\",\n      \"pmids\": [\"19502236\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human GLRX3 (PICOT) binds two bridging [2Fe-2S]2+ clusters in a homodimeric complex, coordinated by active site cysteinyl residues of its two Grx domains and non-covalently bound glutathione. The [2Fe-2S]2+ clusters are lost upon treatment with ferricyanide or S-nitroso glutathione, suggesting redox-induced cluster dissociation as a potential activation mechanism. Co-immunoprecipitation of 55-iron confirmed iron binding under physiological conditions.\",\n      \"method\": \"UV-visible spectroscopy, CD, EPR, 55Fe co-immunoprecipitation, treatment with oxidants\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro spectroscopic reconstitution plus cellular 55Fe co-IP, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"20226171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"S. pombe Grx4 is required for iron-dependent inhibition of Fep1 transcription factor under low-iron conditions. Grx4's TRX domain interacts strongly and constitutively with Fep1's C-terminal region (requiring Cys35), while the GRX domain interacts weakly and iron-dependently with Fep1's N-terminal region (requiring Cys172).\",\n      \"method\": \"Deletion mapping, co-immunoprecipitation, yeast genetics, chromatin binding assays\",\n      \"journal\": \"Eukaryotic cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — domain-mapping mutagenesis combined with in vivo Co-IP and transcriptional assays, defining specific residues and interaction surfaces\",\n      \"pmids\": [\"21421748\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"S. cerevisiae Grx3/Grx4 and Fe-S cluster protein Dre2 contribute to in vivo diferric tyrosyl radical (Fe2(III)-Tyr•) cofactor assembly in ribonucleotide reductase subunit Rnr2; growth defects of rnr4 mutants are enhanced by grx3/grx4 deficiency, placing Grx3/4 in the pathway of iron loading into Rnr2.\",\n      \"method\": \"Genetic epistasis, EPR-based Tyr• measurement, iron loading assays, spheroplast complementation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with biochemical readouts, single lab\",\n      \"pmids\": [\"21931161\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Mouse Grx3 knockout results in embryonic lethality at E12.5; Grx3-deficient MEFs and HeLa knockdown cells show impaired cell cycle progression at G2/M with increased binucleated cells, establishing a direct role in mitotic exit.\",\n      \"method\": \"Knockout mouse (embryonic lethal), flow cytometry cell cycle analysis, siRNA knockdown, immunofluorescence\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with embryonic lethal phenotype plus cell cycle readouts in two cellular systems\",\n      \"pmids\": [\"21575136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PICOT (GLRX3) physically interacts with anamorsin (CIAPIN1/AM) via the N-terminal regions of both proteins; inhibition of this interaction impairs cell growth.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, cell growth assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single yeast two-hybrid plus Co-IP, limited mechanistic follow-up\",\n      \"pmids\": [\"21513700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Fission yeast Grx4 physically interacts with Fep1 in vivo, and mutation of Cys172 (active site of GRX domain) abolishes iron-dependent gene regulation and the Grx4-Fep1 interaction detected by BiFC, indicating that Fe-S cofactor binding in the GRX domain is critical for Fep1 modulation.\",\n      \"method\": \"Co-immunoprecipitation, BiFC, site-directed mutagenesis, transcription assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple interaction assays with mutagenesis, single lab\",\n      \"pmids\": [\"21531205\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PICOT directly binds the catalytic domain of PKCζ via its N-terminal thioredoxin-like domain; purified PICOT inhibits PKCζ kinase activity in vitro. PICOT-mediated PKCζ inhibition down-regulates PKCα and PP2A activities, leading to increased phosphorylation of phospholamban (PLB) and troponin I/T, enhancing SERCA2a activity and cardiomyocyte contractility.\",\n      \"method\": \"Protein pull-down, in vitro kinase assay, PKCζ inhibitor peptide, AAV-mediated overexpression, cardiomyocyte contractility measurements\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro kinase reconstitution plus multiple cellular and in vivo experiments with defined downstream pathway\",\n      \"pmids\": [\"22449794\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PICOT is a caspase-3 cleavage substrate; in vitro cleavage assays show specific cleavage at DRLD(101)/G and EELD(226)/T. Endogenous PICOT is cleaved by caspase-3 during staurosporine- and etoposide-induced apoptosis. PICOT overexpression (WT or cleavage-resistant D101A/D226A) accelerates etoposide-induced caspase-3 activation, while PICOT knockdown blocks it.\",\n      \"method\": \"In vitro caspase cleavage assay, site-directed mutagenesis, pan-caspase inhibitor treatment, siRNA knockdown\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro reconstituted cleavage assay plus mutagenesis plus cellular validation, single lab with orthogonal approaches\",\n      \"pmids\": [\"23415866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Zebrafish depletion of Grx3 severely impairs hemoglobin maturation. Silencing human GLRX3 in HeLa cells decreases activities of cytosolic Fe/S proteins including iron regulatory protein 1 (IRP1), leading to decreased ferritin and increased transferrin receptor levels, a signature of cellular iron starvation despite unimpaired iron uptake.\",\n      \"method\": \"Zebrafish morpholino knockdown, siRNA in HeLa cells, enzyme activity assays, Western blot for IRP1/ferritin/transferrin receptor\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent model systems (zebrafish and human cells) with defined biochemical readouts of Fe/S protein activity and iron metabolism\",\n      \"pmids\": [\"23615448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Human GRX3 and apo BOLA2 form a heterotrimeric complex (two BOLA2 molecules + one GRX3 molecule) that binds two [2Fe-2S]2+ clusters, each bridged between one BOLA2 and one GRX3 Grx domain; this complex transfers both [2Fe-2S]2+ clusters to apo anamorsin to produce its mature holo form, establishing GRX3-BOLA2 as a [2Fe-2S] cluster transfer component in cytosolic Fe/S protein maturation.\",\n      \"method\": \"NMR spectroscopy, UV-visible/CD spectroscopy, in vitro reconstitution and cluster transfer assays\",\n      \"journal\": \"Journal of the American Chemical Society\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — atomic-level NMR characterization plus in vitro reconstitution of cluster transfer, rigorous single study with multiple methods\",\n      \"pmids\": [\"26613676\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Yeast Grx3/4 physically interact with Sir2 sirtuin in vivo and can reverse S-glutathionylation of Sir2 (at cysteines in the catalytic domain) in vitro and in vivo, restoring Sir2 deacetylase activity after disulfide stress; this establishes Grx3/4 as Sir2 thiol-reductases that regulate telomeric silencing via S-deglutathionylation.\",\n      \"method\": \"In vitro deglutathionylation assay, in vivo S-glutathionylation detection, co-immunoprecipitation, site-directed mutagenesis, silencing assay\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro assay plus in vivo validation with mutagenesis, single lab\",\n      \"pmids\": [\"27085841\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Yeast Grx3 and Grx4 physically interact with the MAPK Slt2 in vivo and in vitro, forming Fe/S-bridged complexes where cysteines of Grx3/4 active sites, glutathione, and specific Slt2 cysteines provide ligands. Loss of Grx3/4 impairs Slt2 phosphorylation and Rlm1 transcription upon oxidative stress; Grx4 is the predominant regulator of Slt2 phosphorylation under oxidative conditions.\",\n      \"method\": \"Co-immunoprecipitation (in vivo and in vitro), spectroscopic analysis, mutagenesis, viability and kinase activity assays\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus functional epistasis plus mutagenesis, single lab\",\n      \"pmids\": [\"28007574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"S. pombe Grx4 and its partner Fra2 form a [2Fe-2S]-bridged heterodimer with specific spectroscopic properties; conserved cysteines in Grx4 (Cys172) and Php4 (Cys221, Cys227) are necessary for Fe-S cluster binding and stable Grx4-Php4 complex formation. Grx4 controls Php4 function through binding of a bridging [2Fe-2S] cluster.\",\n      \"method\": \"UV-visible/CD/EPR spectroscopy, in vitro reconstitution, mutagenesis, size exclusion chromatography, in vitro titration\",\n      \"journal\": \"Metallomics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with multi-spectroscopic characterization plus mutagenesis, single lab\",\n      \"pmids\": [\"28725905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structures of the Trx domain (Grx3Trx) and Grx domain (Grx3Grx) of yeast Grx3 were solved; structural analyses revealed that the Trx domain contributes to glutathione S-transferase activity via an inter-domain disulfide between Cys37 and Cys176. NMR titration, pull-down, and SPR assays showed that Fra2 forms a noncovalent heterodimer with Grx3 via an interface between Fra2's helix-turn-helix motif and Grx3Grx's C-terminal segment, independent of the Fe-S-covalent heterodimer.\",\n      \"method\": \"X-ray crystallography, NMR spectroscopy, GST pull-down, surface plasmon resonance, activity assays\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus NMR titration plus SPR in a single study with functional assays\",\n      \"pmids\": [\"29524511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PICOT interacts with EED (a PRC2 core component) via each of its two C-terminal PICOT/Grx homology domains; PICOT and EED co-immunoprecipitate from Jurkat T cell nuclear extracts and partially colocalize in nuclei. PICOT knockdown reduces H3K27me3 at the MYT1 gene promoter, indicating PICOT modulates PRC2-dependent chromatin silencing.\",\n      \"method\": \"Yeast two-hybrid, GST pull-down, reciprocal coimmunoprecipitation, immunofluorescence/confocal microscopy, ChIP (H3K27me3)\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus domain mapping pull-down plus ChIP, single lab\",\n      \"pmids\": [\"30595380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The conserved CDC motif cysteines of yeast Aft2 are essential for [2Fe-2S] cluster binding and Aft2 dimerization, and one of the two cysteines is required for interaction with the [2Fe-2S]-Grx3-Bol2 (Bol2=Fra2 homolog) complex; cluster transfer from Grx3-Bol2 to Aft2 likely occurs through a ligand exchange mechanism.\",\n      \"method\": \"Size exclusion chromatography, circular dichroism spectroscopy, mutagenesis, in vitro cluster transfer assays\",\n      \"journal\": \"Journal of biological inorganic chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro reconstitution/spectroscopy plus mutagenesis, single lab\",\n      \"pmids\": [\"31493153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PICOT-deficient Jurkat T cells show impaired γH2AX foci formation and reduced phosphorylation of ATR, Chk1, and Chk2 in response to genotoxic drugs and radiation; partial localization of PICOT at γH2AX foci at DNA double-strand break sites was observed. PICOT acts as a positive upstream regulator of ATR-dependent DNA damage signaling, independent of ROS levels.\",\n      \"method\": \"siRNA knockdown, immunofluorescence/confocal microscopy, flow cytometry, Western blot for phospho-ATR/Chk1/Chk2/γH2AX\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with multiple defined signaling readouts and localization data, single lab\",\n      \"pmids\": [\"31176019\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PICOT knockdown in Jurkat T cells reduces H3K27me3 at the CCND2 gene promoter, decreases EED and EZH2 occupancy at CCND2, and leads to increased CCND2 (cyclin D2) mRNA and protein expression, establishing PICOT binding to chromatin-associated EED as a modulator of PRC2-mediated repression of CCND2.\",\n      \"method\": \"Coimmunoprecipitation, ChIP (H3K27me3, EED, EZH2), siRNA knockdown, RT-PCR, Western blot\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple ChIP targets with Co-IP and expression readouts confirming mechanistic link, single lab\",\n      \"pmids\": [\"31527584\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Human GLRX3 transfers its [2Fe-2S]2+ clusters to monomeric apo NUBP1 (CIA machinery component); in the presence of glutathione as reductant, the clusters are reductively coupled to form [4Fe-4S]2+ clusters on both N-terminal (CX13CX2CX5C) and C-terminal (CPXC) motifs of NUBP1. Cluster binding at the C-terminal motif promotes NUBP1 dimerization; GLRX3 acts as a [2Fe-2S] cluster chaperone in the early CIA pathway.\",\n      \"method\": \"In vitro reconstitution, UV-visible/CD/EPR spectroscopy, size exclusion chromatography, cluster transfer assays\",\n      \"journal\": \"Journal of the American Chemical Society\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of cluster transfer plus multi-spectroscopic characterization of products, single lab rigorous study\",\n      \"pmids\": [\"32429669\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Human GLRX3 (PICOT) interacts with human GMP synthase (hGMPs) via conserved residues that bridge Fe/S clusters and glutathione; this interaction downregulates the Gcn2/ISR stress pathway. The interaction and pathway function are conserved in yeast (Grx3/Grx4 with GUA1/ScGMPs) and human GLRX3/hGMPs can functionally complement yeast Grx3/Grx4.\",\n      \"method\": \"Yeast humanization complementation, two-hybrid, co-expression, genetic pathway assays (Gcn2 readouts)\",\n      \"journal\": \"Applied and environmental microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic complementation plus interaction assays across two organisms, single lab\",\n      \"pmids\": [\"32414791\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"S. pombe Grx4-Fra2 heterodimer facilitates [2Fe-2S] cluster removal from the Fep1 transcription repressor via unidirectional cluster transfer from Fep1 to Grx4-Fra2 in the presence of GSH; Fra2 His66 and Cys29 serve as Fe-S cluster ligands in the Grx4-Fra2 complex. This defines the Fe-S cluster-dependent mechanism of Fep1 inactivation under low iron.\",\n      \"method\": \"In vitro reconstitution, CD spectroscopy, mutagenesis, in vivo transcription assays, growth assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstituted cluster transfer plus spectroscopy plus mutagenesis plus in vivo validation, single lab rigorous study\",\n      \"pmids\": [\"37923140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In HeLa cells with CRISPR/Cas9 GLRX3 knockout, IRP1 is activated (indicating iron starvation due to impaired iron metabolism). Rescue experiments show that only a Trx-GrxA construct (first Trx-like domain + first Grx domain) restores the phenotype to wild-type levels; the individual domains alone are insufficient, and the second Grx domain (GrxB) is not required for this function.\",\n      \"method\": \"CRISPR/Cas9 knockout, domain rescue transfection, IRP1 activity assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with defined molecular readout and systematic domain rescue, single lab\",\n      \"pmids\": [\"40400140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In satellite glial cells of aged mice, GLRX3 upregulation catalyzes deglutathionylation of HMGB1 at Cys106 via its catalytic Cys148 residue; this converts HMGB1 into a TLR4-MD2 agonist, triggering neuronal NF-κB signaling and upregulation of TRPA1 and TRPV2 channels in nociceptors, sustaining neuropathic pain. Satellite glial cell-targeted knockdown of GLRX3 restored HMGB1 glutathionylation and reversed pain phenotype in aged mice.\",\n      \"method\": \"Single-nucleus RNA sequencing, redox proteomics, site-directed mutagenesis (Cys148), in vivo knockdown, behavioral pain assays, TLR4 signaling assays\",\n      \"journal\": \"Brain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic mutagenesis with in vivo knockdown and multiple pathway readouts, single lab, not yet replicated\",\n      \"pmids\": [\"42007893\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GLRX3 (PICOT) is a multidomain cytosolic monothiol glutaredoxin that coordinates [2Fe-2S] clusters via its CGFS-motif Grx domains and glutathione; it functions as an iron-sulfur cluster chaperone transferring [2Fe-2S] clusters to BOLA2-anamorsin and NUBP1 (CIA machinery), thereby supporting cytosolic Fe/S protein maturation and iron homeostasis. In the nucleus it binds EED/PRC2 to regulate H3K27me3 at target gene promoters. In cardiac tissue, PICOT inhibits hypertrophy by disrupting the MLP-calcineurin interaction to suppress NFAT signaling, and enhances contractility by inhibiting PKCζ, which in turn reduces PKCα and PP2A activities and increases PLB/troponin phosphorylation and SERCA2a activity. PICOT is also a caspase-3 substrate and a positive regulator of ATR-dependent DNA damage signaling, and in aged satellite glial cells GLRX3 deglutathionylates HMGB1 at Cys106 to activate TLR4-mediated nociceptor sensitization.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GLRX3 (PICOT) is a multidomain monothiol glutaredoxin that functions as a [2Fe-2S] cluster chaperone in the cytosolic iron-sulfur cluster assembly (CIA) pathway and as a regulator of cytosolic Fe/S protein maturation and iron homeostasis [#15, #16]. Its Grx domains coordinate bridging [2Fe-2S]2+ clusters together with non-covalently bound glutathione, forming homodimers or, with BOLA2, a heterotrimeric complex that delivers clusters to apo-anamorsin (CIAPIN1) and to NUBP1, where reductive coupling generates [4Fe-4S] clusters [#7, #16, #25]; depletion of GLRX3 produces a cellular iron-starvation signature with activated IRP1, reduced ferritin, and impaired hemoglobin maturation, and a single Trx-Grx unit is sufficient to restore this function [#15, #28]. Loss of Grx3 causes embryonic lethality and a G2/M cell-cycle defect with binucleation, linking Fe/S delivery to mitotic exit [#10]. The conserved cluster-transfer and iron-regulatory role is recapitulated in yeast, where Grx3/Grx4 form [2Fe-2S]-bridged complexes with BolA homologues (Fra2/Bol2) and govern iron-responsive transcription factors (Aft1/Aft2, Php4, Fep1) through cluster-dependent control of their nuclear export and DNA binding [#1, #5, #22, #27]. In cardiac tissue PICOT acts as a negative regulator of hypertrophy and a positive inotropic factor: it binds muscle LIM protein at the Z-disc to disrupt the MLP-calcineurin interaction and suppress calcineurin-NFAT signaling [#3, #4], and binds the catalytic domain of PKCζ to inhibit its kinase activity, down-regulating PKCα and PP2A to increase phospholamban/troponin phosphorylation and SERCA2a-driven contractility [#13]. In the nucleus PICOT binds the PRC2 component EED via its C-terminal Grx domains to modulate H3K27me3 at target promoters including MYT1 and CCND2 [#21, #24]. PICOT additionally serves as a caspase-3 substrate that promotes apoptotic caspase-3 activation [#14] and as a positive upstream regulator of ATR-dependent DNA-damage signaling [#23]. In aged satellite glial cells GLRX3 deglutathionylates HMGB1 at Cys106 through its catalytic Cys148, converting HMGB1 into a TLR4-MD2 agonist that sensitizes nociceptors [#29].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established the first molecular partner and a candidate signaling role by showing PICOT interacts with PKC and dampens stress-kinase/transcription-factor output in T cells.\",\n      \"evidence\": \"Yeast two-hybrid and overexpression reporter assays in T cells\",\n      \"pmids\": [\"10636891\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No biochemical demonstration of direct kinase regulation at this stage\", \"Iron-sulfur/glutaredoxin function not yet recognized\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined the cardiac function of PICOT as an anti-hypertrophic, positive-inotropic factor acting through Ca2+ handling.\",\n      \"evidence\": \"Adenoviral transfer, cardiac-specific transgenic mice, contractility and Ca2+ handling assays\",\n      \"pmids\": [\"16809552\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular target mediating the anti-hypertrophic effect unidentified\", \"Mechanism for enhanced SERCA reuptake undefined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Connected GLRX3 orthologs to iron homeostasis by showing yeast Grx3/Grx4 control nuclear export of the iron-regulatory factor Aft1.\",\n      \"evidence\": \"Co-IP, in vitro binding, GFP localization, deletion genetics in S. cerevisiae\",\n      \"pmids\": [\"17074835\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Chemical basis of iron sensing not established\", \"Relevance to human GLRX3 not yet shown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified the molecular mechanism of cardiac anti-hypertrophy: PICOT binds MLP at the Z-disc and competitively disrupts MLP-calcineurin signaling to NFAT.\",\n      \"evidence\": \"GST pull-down/MS, reciprocal Co-IP, immunofluorescence, pressure-overload transgenic and PICOT(+/-) mice\",\n      \"pmids\": [\"18258855\", \"18929570\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether glutaredoxin/Fe-S activity contributes to the cardiac role unknown\", \"Stoichiometry of MLP-calcineurin displacement not resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Provided the chemical basis for iron sensing, demonstrating Grx3/4 bind bridging [2Fe-2S] clusters as homodimers or as Fra2 (BolA) heterodimers coordinated by active-site cysteine, glutathione, and a Fra2 histidine.\",\n      \"evidence\": \"E. coli reconstitution with multi-spectroscopic characterization and mutagenesis; Co-IP/BiFC/Y2H for Crm1 and Php4 in fission yeast\",\n      \"pmids\": [\"19715344\", \"19502236\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direction of cluster trafficking (sensing vs. delivery) not yet defined\", \"Human protein cluster coordination not yet confirmed\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Confirmed that human GLRX3 binds two bridging [2Fe-2S] clusters via its Grx domains and glutathione, with oxidant-induced cluster loss as a candidate switch.\",\n      \"evidence\": \"UV-vis/CD/EPR spectroscopy and 55Fe co-IP of human GLRX3\",\n      \"pmids\": [\"20226171\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological recipients of the clusters not identified\", \"In vivo significance of redox-induced cluster dissociation untested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Linked GLRX3 to cytosolic Fe/S maturation and cell division by establishing essential roles in mitotic exit and a physical link to anamorsin.\",\n      \"evidence\": \"Embryonic-lethal Grx3 knockout mouse, cell-cycle flow cytometry, siRNA in HeLa; yeast genetic epistasis with Dre2/Rnr; Y2H/Co-IP with anamorsin\",\n      \"pmids\": [\"21575136\", \"21931161\", \"21513700\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanistic basis of G2/M arrest not defined\", \"Anamorsin interaction lacked reciprocal/biochemical depth at this stage\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Resolved how the Grx domain controls an iron-responsive repressor, mapping Trx- and Grx-domain interactions and the requirement of Grx Cys172/Fe-S binding for Fep1 regulation.\",\n      \"evidence\": \"Domain mapping, Co-IP, BiFC, site-directed mutagenesis and transcription assays in S. pombe\",\n      \"pmids\": [\"21421748\", \"21531205\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cluster transfer chemistry to/from Fep1 not yet demonstrated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated that human GLRX3 is required for cytosolic Fe/S protein activity and organismal iron handling, producing an iron-starvation signature when depleted.\",\n      \"evidence\": \"Zebrafish morpholino, HeLa siRNA, IRP1/ferritin/transferrin-receptor readouts and Fe/S enzyme assays\",\n      \"pmids\": [\"23615448\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct cluster recipients in human cells not yet identified\", \"Distinction between chaperone vs. signaling role unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined the biochemical link from PICOT to cardiac contractility and identified PICOT as a caspase-3 substrate that promotes apoptosis.\",\n      \"evidence\": \"In vitro kinase assays/pull-down for PKCζ with AAV overexpression and contractility; in vitro caspase cleavage assays with cleavage-resistant mutants and knockdown\",\n      \"pmids\": [\"22449794\", \"23415866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Fe-S/glutaredoxin activity contributes to PKCζ inhibition unknown\", \"Functional consequence of PICOT cleavage fragments undefined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established GLRX3 as a [2Fe-2S] cluster transfer agent in the CIA pathway by showing a GRX3-BOLA2 heterotrimer delivers clusters to apo-anamorsin.\",\n      \"evidence\": \"NMR and UV-vis/CD spectroscopy with in vitro reconstitution and cluster transfer assays\",\n      \"pmids\": [\"26613676\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Source of clusters delivered to GRX3-BOLA2 not defined\", \"Regulation of transfer directionality unaddressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Expanded the glutaredoxin enzymatic repertoire, showing Grx3/4 deglutathionylate Sir2 and form Fe-S-bridged complexes with the MAPK Slt2 to regulate oxidative-stress signaling.\",\n      \"evidence\": \"In vitro/in vivo deglutathionylation, Co-IP, spectroscopy and mutagenesis in yeast\",\n      \"pmids\": [\"27085841\", \"28007574\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Human relevance of Sir2/Slt2 regulation not tested\", \"Single-lab findings without independent replication\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Provided structural and chromatin-regulatory mechanism, solving Grx3 Trx/Grx domain structures and defining a non-covalent Fra2-Grx3 interface, and linking PICOT to PRC2 via EED.\",\n      \"evidence\": \"X-ray crystallography, NMR titration, SPR and activity assays (yeast); Y2H, GST pull-down, reciprocal Co-IP and H3K27me3 ChIP (human)\",\n      \"pmids\": [\"29524511\", \"30595380\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional impact of the non-covalent vs. covalent Fra2-Grx3 interfaces unresolved\", \"How PICOT alters PRC2 catalysis mechanistically unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Detailed the cluster-dependent mechanism of iron-regulator inactivation and added nuclear and DNA-damage roles for PICOT.\",\n      \"evidence\": \"In vitro reconstitution/CD with mutagenesis (Php4/Aft2); siRNA with phospho-ATR/Chk1/Chk2/γH2AX readouts and ChIP for CCND2 (human)\",\n      \"pmids\": [\"28725905\", \"31493153\", \"31176019\", \"31527584\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PICOT promotes ATR activation undefined\", \"Whether DNA-damage and chromatin roles depend on Fe-S binding untested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established GLRX3 as an early-CIA cluster chaperone for NUBP1 and connected it to nucleotide-metabolism stress signaling via GMP synthase.\",\n      \"evidence\": \"In vitro reconstitution/spectroscopy of NUBP1 cluster transfer; yeast humanization complementation and interaction assays for GMP synthase\",\n      \"pmids\": [\"32429669\", \"32414791\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In-cell hierarchy among GLRX3 recipients (anamorsin, NUBP1) not defined\", \"Physiological control of [2Fe-2S]→[4Fe-4S] coupling unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved the directionality of cluster trafficking in iron sensing, showing unidirectional [2Fe-2S] removal from Fep1 by the Grx4-Fra2 heterodimer.\",\n      \"evidence\": \"In vitro reconstitution, CD spectroscopy, mutagenesis and in vivo transcription/growth assays in S. pombe\",\n      \"pmids\": [\"37923140\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human GLRX3 performs analogous extraction from a target unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Mapped the minimal functional unit for human iron metabolism, showing a single Trx-Grx domain pair is sufficient to rescue the iron-starvation phenotype.\",\n      \"evidence\": \"CRISPR/Cas9 GLRX3 knockout with systematic domain-rescue and IRP1 activity readout in HeLa\",\n      \"pmids\": [\"40400140\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Role of the second Grx domain in other functions not addressed\", \"Quantitative cluster occupancy of rescue constructs not measured\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Defined a glutaredoxin catalytic role in disease, showing GLRX3 deglutathionylates HMGB1 to generate a TLR4 agonist that drives nociceptor sensitization in aged mice.\",\n      \"evidence\": \"snRNA-seq, redox proteomics, Cys148 mutagenesis, in vivo glial knockdown and behavioral pain assays\",\n      \"pmids\": [\"42007893\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab finding not independently replicated\", \"Whether Fe-S binding modulates the deglutathionylase activity in this context untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How GLRX3's distinct activities — Fe/S cluster chaperone, cardiac signaling regulator, PRC2 modulator, DNA-damage signaling, and substrate deglutathionylase — are coordinated within one cell, and whether each depends on its iron-sulfur cluster, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No integrated model linking Fe/S chaperone activity to the cardiac, chromatin, and nociceptive roles\", \"Upstream cluster donor to human GLRX3 not identified\", \"Regulatory switch controlling which function dominates in a given tissue unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [17, 29]},\n      {\"term_id\": \"GO:0140104\", \"supporting_discovery_ids\": [7, 16, 25]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 13]},\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [17, 29]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [7, 15, 16]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [21, 24]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [15, 16, 25]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [21, 24]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 13]}\n    ],\n    \"complexes\": [\n      \"GRX3-BOLA2 [2Fe-2S] heterotrimer\",\n      \"PRC2 (via EED)\"\n    ],\n    \"partners\": [\n      \"BOLA2\",\n      \"CIAPIN1\",\n      \"NUBP1\",\n      \"MLP\",\n      \"PRKCZ\",\n      \"EED\",\n      \"HMGB1\",\n      \"GMPS\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}