{"gene":"HINT3","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2007,"finding":"Human HINT3-1 and HINT3-2 are adenylate and phosphoramidate hydrolases; active-site His145 (aligned with His112 of HINT1) is essential for catalytic activity, as H145A mutation abolishes adenylate and phosphoramidate hydrolase activity. HINT3 can hydrolyze lysyl-adenylate generated by human lysyl-tRNA synthetase (hLysRS), proceeding through an adenylated protein intermediate dependent on His145.","method":"Steady-state kinetic assays with fluorogenic substrates, active-site mutagenesis (H145A), in vitro reconstitution with hLysRS","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic reconstitution plus active-site mutagenesis in single rigorous study","pmids":["17870088"],"is_preprint":false},{"year":2007,"finding":"Unlike HINT1 (exclusively homodimeric), HINT3-1 exists across a range of multimeric states (dimers to octamers and larger oligomers), while HINT3-2 (A36G SNP) exists predominantly as a monomer. This oligomeric difference correlates with distinct subcellular localization: tetracysteine-tagged HINT3-1 and HINT3-2 form aggregates in both cytosol and nucleus, whereas tagged HINT1 localizes exclusively along linear arrays in the cytoplasm of transfected HeLa cells.","method":"Size-exclusion chromatography/analytical ultracentrifugation for oligomeric state; tetracysteine-tag live-cell imaging in transfected HeLa cells for subcellular localization","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — direct localization experiment plus biophysical characterization, single lab, two orthogonal methods","pmids":["17870088"],"is_preprint":false},{"year":2007,"finding":"HINT3 prefers aminoacyl-adenylate substrates (AIPA) over tryptamine nucleoside phosphoramidate by 16–33-fold, and hydrolyzes phosphoramidates 370- to 2000-fold less efficiently than HINT1, placing HINT3 in a biochemically distinct branch of the HIT superfamily.","method":"Steady-state kinetic assays with fluorogenic synthetic substrates (kcat/Km determination)","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous in vitro enzyme kinetics with multiple substrates and two protein variants in a single focused study","pmids":["17870088"],"is_preprint":false},{"year":2025,"finding":"HINT3 shows hydrolase activity toward synthetic mononucleotide phosphoramidate derivatives and dinucleotide polyphosphates; it favors adenosine over guanosine derivatives. Structure modeling of the HINT3(Gly36) monomeric variant reveals a helix α3 (absent in HINT1/HINT2 but present in Aprataxin) and two potential disulfide bond sites, placing HINT3 closer to Aprataxin than to HINT1/HINT2 in the HIT superfamily.","method":"In vitro hydrolase activity assays with diverse substrate panels, Kd binding measurements, 3D structural modeling and docking simulation with AMP","journal":"Bioorganic chemistry","confidence":"Medium","confidence_rationale":"Tier 1-2 / Weak — in vitro biochemistry plus computational modeling, single lab, no mutagenesis validation of structural predictions","pmids":["41172780"],"is_preprint":false},{"year":2025,"finding":"HINT3 interacts physically with succinate dehydrogenase subunit A (SDHA), suppresses HDAC1 expression, and prevents SDHA deacetylation at K335, thereby reducing SDH activity and mitochondrial ROS production during myocardial ischemia-reperfusion injury. Cardiomyocyte-specific HINT3 knockout exacerbates injury and mitochondrial dysfunction, while HINT3 overexpression is protective.","method":"Co-immunoprecipitation (HINT3–SDHA interaction), cardiomyocyte-specific knockout and overexpression in mouse I/R model and OGD/R cellular model, acetylation site mapping at K335, SDH activity assay, ROS measurement","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, genetic loss- and gain-of-function with defined molecular readouts, single lab","pmids":["40755357"],"is_preprint":false},{"year":2025,"finding":"USP11 deubiquitinates and stabilizes HINT3 by reversing its polyubiquitination-mediated degradation; HINT3 in turn physically interacts with the anti-apoptotic protein BCL2, and HINT3 knockdown depletes BCL2 levels, reducing endothelial apoptosis resistance in pulmonary arterial hypertension.","method":"Co-immunoprecipitation (USP11–HINT3 and HINT3–BCL2 interactions), siRNA knockdown of HINT3, USP11 overexpression with BCL2 protein measurement in human pulmonary arterial endothelial cells (HPAECs)","journal":"Journal of respiratory biology and translational medicine","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — reciprocal Co-IP plus functional KD with defined protein-level readout, single lab, two orthogonal methods","pmids":["40376595"],"is_preprint":false},{"year":2023,"finding":"HINT3 upregulates PTEN at the transcriptional level, leading to inactivation of AKT/mTOR signaling; HINT3 knockdown promotes proliferation and migration of breast cancer cells, while HINT3 overexpression suppresses tumorigenesis in mouse xenograft models.","method":"siRNA knockdown and ectopic overexpression in MCF-7 and MDA-MB-231 cells; in vivo mouse tumor xenograft; RT-qPCR and western blot for PTEN/AKT/mTOR pathway; proliferation and migration assays","journal":"International journal of molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD/KO and OE with defined pathway readout in vitro and in vivo, single lab, multiple orthogonal assays","pmids":["37203409"],"is_preprint":false}],"current_model":"HINT3 is a eukaryote-specific member of the HIT superfamily that functions as an adenylate and phosphoramidate hydrolase (with His145 as the catalytic nucleophile), preferring aminoacyl-adenylate substrates and capable of cleaving lysyl-adenylate intermediates generated by lysyl-tRNA synthetase; it exists in a distinct oligomeric state compared to HINT1, localizes to both cytosol and nucleus, regulates mitochondrial function by interacting with SDHA and suppressing HDAC1-mediated SDHA deacetylation to limit ROS production, is stabilized by the deubiquitinase USP11 and interacts with BCL2 to promote endothelial apoptosis resistance, and suppresses breast cancer cell proliferation and migration by transcriptionally upregulating PTEN to inactivate AKT/mTOR signaling."},"narrative":{"mechanistic_narrative":"HINT3 is a eukaryote-specific member of the HIT superfamily that acts as an adenylate and phosphoramidate hydrolase, using an active-site histidine (His145, aligned with HINT1 His112) as the catalytic nucleophile and proceeding through an adenylated protein intermediate; it preferentially hydrolyzes aminoacyl-adenylate substrates and can cleave the lysyl-adenylate intermediate generated by lysyl-tRNA synthetase [PMID:17870088]. Biochemically and structurally it diverges from HINT1/HINT2 — adopting a range of oligomeric states rather than an obligate homodimer and possessing an Aprataxin-like helix α3 — placing it in a distinct branch of the HIT family, and it distributes to both cytosol and nucleus [PMID:17870088, PMID:41172780]. Beyond its catalytic identity, HINT3 has been linked to several cellular regulatory roles: it physically interacts with the succinate dehydrogenase subunit SDHA and suppresses HDAC1-mediated SDHA deacetylation at K335 to limit SDH activity and mitochondrial ROS, conferring protection in myocardial ischemia-reperfusion injury [PMID:40755357]; it is stabilized by the deubiquitinase USP11 and interacts with BCL2 to support endothelial apoptosis resistance [PMID:40376595]; and it suppresses breast cancer cell proliferation and migration by transcriptionally upregulating PTEN to inactivate AKT/mTOR signaling [PMID:37203409]. How its hydrolase activity mechanistically connects to these protein-interaction and signaling functions has not been established in the available corpus.","teleology":[{"year":2007,"claim":"Established HINT3's molecular identity as a HIT-superfamily hydrolase and pinpointed its catalytic mechanism, answering whether this uncharacterized HINT paralog retained enzymatic activity.","evidence":"Steady-state kinetics with fluorogenic substrates, H145A active-site mutagenesis, and in vitro reconstitution with hLysRS","pmids":["17870088"],"confidence":"High","gaps":["No physiological substrate identified in cells","Significance of cleaving lysyl-adenylate for tRNA charging or translation untested in vivo"]},{"year":2007,"claim":"Showed HINT3 is biochemically and structurally distinct from HINT1 in substrate preference, oligomeric behavior, and localization, defining it as a separate functional branch rather than a HINT1 redundant copy.","evidence":"Kinetic profiling across substrates, SEC/AUC oligomeric analysis, and tetracysteine-tag live imaging in HeLa cells","pmids":["17870088"],"confidence":"Medium","gaps":["Functional consequence of the multimeric range vs HINT1 dimer unknown","Tag-induced aggregation may confound native localization","No endogenous localization data"]},{"year":2023,"claim":"Linked HINT3 to tumor suppression, addressing whether the enzyme has a cellular signaling role beyond in vitro catalysis.","evidence":"siRNA knockdown and overexpression in breast cancer lines plus mouse xenograft, with PTEN/AKT/mTOR pathway readouts","pmids":["37203409"],"confidence":"Medium","gaps":["Mechanism by which HINT3 transcriptionally upregulates PTEN unknown","Whether His145 hydrolase activity is required for tumor suppression untested"]},{"year":2025,"claim":"Connected HINT3 to mitochondrial redox control via SDHA, establishing a protective role in ischemia-reperfusion injury through an acetylation-regulatory mechanism.","evidence":"Reciprocal Co-IP, cardiomyocyte-specific knockout and overexpression in mouse I/R and OGD/R models, K335 acetylation mapping, SDH activity and ROS assays","pmids":["40755357"],"confidence":"Medium","gaps":["How HINT3 suppresses HDAC1 expression mechanistically unclear","Whether the SDHA interaction depends on HINT3 catalytic activity untested"]},{"year":2025,"claim":"Identified HINT3 stabilization by USP11 and a BCL2 interaction governing endothelial apoptosis resistance, adding a ubiquitin-regulated survival axis.","evidence":"Reciprocal Co-IP for USP11–HINT3 and HINT3–BCL2, siRNA knockdown and USP11 overexpression with BCL2 protein readouts in HPAECs","pmids":["40376595"],"confidence":"Medium","gaps":["Ubiquitin ligase that opposes USP11 not identified","Direct vs indirect nature of HINT3–BCL2 effect on BCL2 levels unresolved"]},{"year":2025,"claim":"Refined HINT3's substrate range and structural placement, showing nucleotide-derivative hydrolysis with adenosine preference and an Aprataxin-like architecture.","evidence":"In vitro hydrolase assays across substrate panels, Kd measurements, and 3D structural modeling/docking of the Gly36 monomeric variant","pmids":["41172780"],"confidence":"Medium","gaps":["Structural predictions (helix α3, disulfide sites) not validated by mutagenesis or experimental structure","No physiological substrate confirmed"]},{"year":null,"claim":"Whether HINT3's hydrolase activity mechanistically underlies its protein-interaction and signaling roles (SDHA, BCL2, PTEN axes) remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No study tests whether His145 catalysis is required for any cellular phenotype","Endogenous physiological substrate unidentified","No unifying mechanism linking enzyme activity to the diverse interactomes"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0,2,3]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1]}],"pathway":[],"complexes":[],"partners":["SDHA","BCL2","USP11"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NQE9","full_name":"Adenosine 5'-monophosphoramidase HINT3","aliases":["Histidine triad nucleotide-binding protein 3","HINT-3"],"length_aa":182,"mass_kda":20.4,"function":"Exhibits adenosine 5'-monophosphoramidase activity, hydrolyzing purine nucleotide phosphoramidates with a single phosphate group such as adenosine 5'monophosphoramidate (AMP-NH2) to yield AMP and NH2 (PubMed:17870088). Hydrolyzes lysyl-AMP (AMP-N-epsilon-(N-alpha-acetyl lysine methyl ester)) generated by lysine tRNA ligase (PubMed:17870088). Hydrolyzes 3-indolepropionic acyl-adenylate and fluorogenic purine nucleoside tryptamine phosphoramidates in vitro (PubMed:17870088)","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9NQE9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HINT3","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/HINT3","total_profiled":1310},"omim":[{"mim_id":"609998","title":"HISTIDINE TRIAD NUCLEOTIDE-BINDING PROTEIN 3; HINT3","url":"https://www.omim.org/entry/609998"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli","reliability":"Approved"},{"location":"Mitochondria","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"skeletal muscle","ntpm":105.5}],"url":"https://www.proteinatlas.org/search/HINT3"},"hgnc":{"alias_symbol":["FLJ33126","HINT4"],"prev_symbol":[]},"alphafold":{"accession":"Q9NQE9","domains":[{"cath_id":"3.30.428.10","chopping":"64-182","consensus_level":"high","plddt":95.9746,"start":64,"end":182}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQE9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQE9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQE9-F1-predicted_aligned_error_v6.png","plddt_mean":85.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HINT3","jax_strain_url":"https://www.jax.org/strain/search?query=HINT3"},"sequence":{"accession":"Q9NQE9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NQE9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NQE9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQE9"}},"corpus_meta":[{"pmid":"12748294","id":"PMC_12748294","title":"The histidine triad protein Hint is not required for murine development or Cdk7 function.","date":"2003","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/12748294","citation_count":24,"is_preprint":false},{"pmid":"23298258","id":"PMC_23298258","title":"All-trans retinoic acid protects hepatocellular carcinoma cells against serum-starvation-induced cell death by upregulating collagen 8A2.","date":"2013","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/23298258","citation_count":23,"is_preprint":false},{"pmid":"34504491","id":"PMC_34504491","title":"The Role of Hemoglobin Subunit Delta in the Immunopathy of Multiple Sclerosis: Mitochondria Matters.","date":"2021","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/34504491","citation_count":14,"is_preprint":false},{"pmid":"17870088","id":"PMC_17870088","title":"Evidence that human histidine triad nucleotide binding protein 3 (Hint3) is a distinct branch of the histidine triad (HIT) superfamily.","date":"2007","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17870088","citation_count":13,"is_preprint":false},{"pmid":"38245717","id":"PMC_38245717","title":"The integration of multidisciplinary approaches revealed PTGES3 as a novel drug target for breast cancer treatment.","date":"2024","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/38245717","citation_count":13,"is_preprint":false},{"pmid":"37311930","id":"PMC_37311930","title":"Integrated Machine Learning and Bioinformatic Analyses Constructed a Network Between Mitochondrial Dysfunction and Immune Microenvironment of Periodontitis.","date":"2023","source":"Inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/37311930","citation_count":12,"is_preprint":false},{"pmid":"40755357","id":"PMC_40755357","title":"The Role of HINT3 in Myocardial Ischemia-Reperfusion Injury in Male Mice: Mechanisms Involving SDHA and its Acetylation.","date":"2025","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/40755357","citation_count":5,"is_preprint":false},{"pmid":"38033384","id":"PMC_38033384","title":"A Systems Biology Approach for Investigating Significant Biomarkers and Drug Targets Common Among Patients with Gonorrhea, Chlamydia, and Prostate Cancer: A Pilot Study.","date":"2023","source":"Bioinformatics and biology insights","url":"https://pubmed.ncbi.nlm.nih.gov/38033384","citation_count":4,"is_preprint":false},{"pmid":"37203409","id":"PMC_37203409","title":"HINT3 suppresses AKT/mTOR signaling pathway activity during breast cancer tumorigenesis through PTEN transcriptional activation.","date":"2023","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37203409","citation_count":3,"is_preprint":false},{"pmid":"21303680","id":"PMC_21303680","title":"Monocyte-mediated regulation of genes by the amyloid and prion peptides in SH-SY5Y neuroblastoma cells.","date":"2011","source":"Neurochemistry international","url":"https://pubmed.ncbi.nlm.nih.gov/21303680","citation_count":3,"is_preprint":false},{"pmid":"39164264","id":"PMC_39164264","title":"Haplotype analysis identifies functional elements in monoclonal gammopathy of unknown significance.","date":"2024","source":"Blood cancer journal","url":"https://pubmed.ncbi.nlm.nih.gov/39164264","citation_count":1,"is_preprint":false},{"pmid":"41172780","id":"PMC_41172780","title":"Biochemical and biophysical characterization, and 3D structure modeling of human HINT3, a hydrolase of the HIT superfamily.","date":"2025","source":"Bioorganic chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41172780","citation_count":0,"is_preprint":false},{"pmid":"40376595","id":"PMC_40376595","title":"USP11 Promotes Endothelial Apoptosis-Resistance in Pulmonary Arterial Hypertension by Deubiquitinating HINT3.","date":"2025","source":"Journal of respiratory biology and translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40376595","citation_count":0,"is_preprint":false},{"pmid":"41516028","id":"PMC_41516028","title":"Endometriosis: From Genes to Global Burden.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41516028","citation_count":0,"is_preprint":false},{"pmid":"36520227","id":"PMC_36520227","title":"Redox homeostasis at SAM: a new role of HINT protein.","date":"2022","source":"Planta","url":"https://pubmed.ncbi.nlm.nih.gov/36520227","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10968,"output_tokens":2073,"usd":0.032,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9070,"output_tokens":2439,"usd":0.053163,"stage2_stop_reason":"end_turn"},"total_usd":0.085163,"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\": 2007,\n      \"finding\": \"Human HINT3-1 and HINT3-2 are adenylate and phosphoramidate hydrolases; active-site His145 (aligned with His112 of HINT1) is essential for catalytic activity, as H145A mutation abolishes adenylate and phosphoramidate hydrolase activity. HINT3 can hydrolyze lysyl-adenylate generated by human lysyl-tRNA synthetase (hLysRS), proceeding through an adenylated protein intermediate dependent on His145.\",\n      \"method\": \"Steady-state kinetic assays with fluorogenic substrates, active-site mutagenesis (H145A), in vitro reconstitution with hLysRS\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic reconstitution plus active-site mutagenesis in single rigorous study\",\n      \"pmids\": [\"17870088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Unlike HINT1 (exclusively homodimeric), HINT3-1 exists across a range of multimeric states (dimers to octamers and larger oligomers), while HINT3-2 (A36G SNP) exists predominantly as a monomer. This oligomeric difference correlates with distinct subcellular localization: tetracysteine-tagged HINT3-1 and HINT3-2 form aggregates in both cytosol and nucleus, whereas tagged HINT1 localizes exclusively along linear arrays in the cytoplasm of transfected HeLa cells.\",\n      \"method\": \"Size-exclusion chromatography/analytical ultracentrifugation for oligomeric state; tetracysteine-tag live-cell imaging in transfected HeLa cells for subcellular localization\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — direct localization experiment plus biophysical characterization, single lab, two orthogonal methods\",\n      \"pmids\": [\"17870088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"HINT3 prefers aminoacyl-adenylate substrates (AIPA) over tryptamine nucleoside phosphoramidate by 16–33-fold, and hydrolyzes phosphoramidates 370- to 2000-fold less efficiently than HINT1, placing HINT3 in a biochemically distinct branch of the HIT superfamily.\",\n      \"method\": \"Steady-state kinetic assays with fluorogenic synthetic substrates (kcat/Km determination)\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous in vitro enzyme kinetics with multiple substrates and two protein variants in a single focused study\",\n      \"pmids\": [\"17870088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HINT3 shows hydrolase activity toward synthetic mononucleotide phosphoramidate derivatives and dinucleotide polyphosphates; it favors adenosine over guanosine derivatives. Structure modeling of the HINT3(Gly36) monomeric variant reveals a helix α3 (absent in HINT1/HINT2 but present in Aprataxin) and two potential disulfide bond sites, placing HINT3 closer to Aprataxin than to HINT1/HINT2 in the HIT superfamily.\",\n      \"method\": \"In vitro hydrolase activity assays with diverse substrate panels, Kd binding measurements, 3D structural modeling and docking simulation with AMP\",\n      \"journal\": \"Bioorganic chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Weak — in vitro biochemistry plus computational modeling, single lab, no mutagenesis validation of structural predictions\",\n      \"pmids\": [\"41172780\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HINT3 interacts physically with succinate dehydrogenase subunit A (SDHA), suppresses HDAC1 expression, and prevents SDHA deacetylation at K335, thereby reducing SDH activity and mitochondrial ROS production during myocardial ischemia-reperfusion injury. Cardiomyocyte-specific HINT3 knockout exacerbates injury and mitochondrial dysfunction, while HINT3 overexpression is protective.\",\n      \"method\": \"Co-immunoprecipitation (HINT3–SDHA interaction), cardiomyocyte-specific knockout and overexpression in mouse I/R model and OGD/R cellular model, acetylation site mapping at K335, SDH activity assay, ROS measurement\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, genetic loss- and gain-of-function with defined molecular readouts, single lab\",\n      \"pmids\": [\"40755357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP11 deubiquitinates and stabilizes HINT3 by reversing its polyubiquitination-mediated degradation; HINT3 in turn physically interacts with the anti-apoptotic protein BCL2, and HINT3 knockdown depletes BCL2 levels, reducing endothelial apoptosis resistance in pulmonary arterial hypertension.\",\n      \"method\": \"Co-immunoprecipitation (USP11–HINT3 and HINT3–BCL2 interactions), siRNA knockdown of HINT3, USP11 overexpression with BCL2 protein measurement in human pulmonary arterial endothelial cells (HPAECs)\",\n      \"journal\": \"Journal of respiratory biology and translational medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — reciprocal Co-IP plus functional KD with defined protein-level readout, single lab, two orthogonal methods\",\n      \"pmids\": [\"40376595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HINT3 upregulates PTEN at the transcriptional level, leading to inactivation of AKT/mTOR signaling; HINT3 knockdown promotes proliferation and migration of breast cancer cells, while HINT3 overexpression suppresses tumorigenesis in mouse xenograft models.\",\n      \"method\": \"siRNA knockdown and ectopic overexpression in MCF-7 and MDA-MB-231 cells; in vivo mouse tumor xenograft; RT-qPCR and western blot for PTEN/AKT/mTOR pathway; proliferation and migration assays\",\n      \"journal\": \"International journal of molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD/KO and OE with defined pathway readout in vitro and in vivo, single lab, multiple orthogonal assays\",\n      \"pmids\": [\"37203409\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HINT3 is a eukaryote-specific member of the HIT superfamily that functions as an adenylate and phosphoramidate hydrolase (with His145 as the catalytic nucleophile), preferring aminoacyl-adenylate substrates and capable of cleaving lysyl-adenylate intermediates generated by lysyl-tRNA synthetase; it exists in a distinct oligomeric state compared to HINT1, localizes to both cytosol and nucleus, regulates mitochondrial function by interacting with SDHA and suppressing HDAC1-mediated SDHA deacetylation to limit ROS production, is stabilized by the deubiquitinase USP11 and interacts with BCL2 to promote endothelial apoptosis resistance, and suppresses breast cancer cell proliferation and migration by transcriptionally upregulating PTEN to inactivate AKT/mTOR signaling.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HINT3 is a eukaryote-specific member of the HIT superfamily that acts as an adenylate and phosphoramidate hydrolase, using an active-site histidine (His145, aligned with HINT1 His112) as the catalytic nucleophile and proceeding through an adenylated protein intermediate; it preferentially hydrolyzes aminoacyl-adenylate substrates and can cleave the lysyl-adenylate intermediate generated by lysyl-tRNA synthetase [#0, #2]. Biochemically and structurally it diverges from HINT1/HINT2 — adopting a range of oligomeric states rather than an obligate homodimer and possessing an Aprataxin-like helix α3 — placing it in a distinct branch of the HIT family, and it distributes to both cytosol and nucleus [#1, #3]. Beyond its catalytic identity, HINT3 has been linked to several cellular regulatory roles: it physically interacts with the succinate dehydrogenase subunit SDHA and suppresses HDAC1-mediated SDHA deacetylation at K335 to limit SDH activity and mitochondrial ROS, conferring protection in myocardial ischemia-reperfusion injury [#4]; it is stabilized by the deubiquitinase USP11 and interacts with BCL2 to support endothelial apoptosis resistance [#5]; and it suppresses breast cancer cell proliferation and migration by transcriptionally upregulating PTEN to inactivate AKT/mTOR signaling [#6]. How its hydrolase activity mechanistically connects to these protein-interaction and signaling functions has not been established in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established HINT3's molecular identity as a HIT-superfamily hydrolase and pinpointed its catalytic mechanism, answering whether this uncharacterized HINT paralog retained enzymatic activity.\",\n      \"evidence\": \"Steady-state kinetics with fluorogenic substrates, H145A active-site mutagenesis, and in vitro reconstitution with hLysRS\",\n      \"pmids\": [\"17870088\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No physiological substrate identified in cells\", \"Significance of cleaving lysyl-adenylate for tRNA charging or translation untested in vivo\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showed HINT3 is biochemically and structurally distinct from HINT1 in substrate preference, oligomeric behavior, and localization, defining it as a separate functional branch rather than a HINT1 redundant copy.\",\n      \"evidence\": \"Kinetic profiling across substrates, SEC/AUC oligomeric analysis, and tetracysteine-tag live imaging in HeLa cells\",\n      \"pmids\": [\"17870088\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the multimeric range vs HINT1 dimer unknown\", \"Tag-induced aggregation may confound native localization\", \"No endogenous localization data\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Linked HINT3 to tumor suppression, addressing whether the enzyme has a cellular signaling role beyond in vitro catalysis.\",\n      \"evidence\": \"siRNA knockdown and overexpression in breast cancer lines plus mouse xenograft, with PTEN/AKT/mTOR pathway readouts\",\n      \"pmids\": [\"37203409\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which HINT3 transcriptionally upregulates PTEN unknown\", \"Whether His145 hydrolase activity is required for tumor suppression untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected HINT3 to mitochondrial redox control via SDHA, establishing a protective role in ischemia-reperfusion injury through an acetylation-regulatory mechanism.\",\n      \"evidence\": \"Reciprocal Co-IP, cardiomyocyte-specific knockout and overexpression in mouse I/R and OGD/R models, K335 acetylation mapping, SDH activity and ROS assays\",\n      \"pmids\": [\"40755357\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How HINT3 suppresses HDAC1 expression mechanistically unclear\", \"Whether the SDHA interaction depends on HINT3 catalytic activity untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified HINT3 stabilization by USP11 and a BCL2 interaction governing endothelial apoptosis resistance, adding a ubiquitin-regulated survival axis.\",\n      \"evidence\": \"Reciprocal Co-IP for USP11–HINT3 and HINT3–BCL2, siRNA knockdown and USP11 overexpression with BCL2 protein readouts in HPAECs\",\n      \"pmids\": [\"40376595\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitin ligase that opposes USP11 not identified\", \"Direct vs indirect nature of HINT3–BCL2 effect on BCL2 levels unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Refined HINT3's substrate range and structural placement, showing nucleotide-derivative hydrolysis with adenosine preference and an Aprataxin-like architecture.\",\n      \"evidence\": \"In vitro hydrolase assays across substrate panels, Kd measurements, and 3D structural modeling/docking of the Gly36 monomeric variant\",\n      \"pmids\": [\"41172780\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural predictions (helix α3, disulfide sites) not validated by mutagenesis or experimental structure\", \"No physiological substrate confirmed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether HINT3's hydrolase activity mechanistically underlies its protein-interaction and signaling roles (SDHA, BCL2, PTEN axes) remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No study tests whether His145 catalysis is required for any cellular phenotype\", \"Endogenous physiological substrate unidentified\", \"No unifying mechanism linking enzyme activity to the diverse interactomes\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [],\n    \"complexes\": [],\n    \"partners\": [\"SDHA\", \"BCL2\", \"USP11\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":3,"faith_total":3,"faith_pct":100.0}}