{"gene":"GRINA","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":2012,"finding":"TMBIM3/GRINA is transcriptionally upregulated by ER stress via the PERK signaling branch of the unfolded protein response. TMBIM3/GRINA modulates ER calcium homeostasis and apoptosis through physical interaction with inositol trisphosphate receptors (IP3Rs). It synergizes with TMBIM6/BI-1 in ER stress protection in vivo (Drosophila and zebrafish models).","method":"Co-immunoprecipitation (physical interaction with IP3Rs), loss-of-function studies in Drosophila and zebrafish, PERK branch manipulation, calcium homeostasis assays","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP for IP3R interaction, multiple orthogonal methods (biochemical, Drosophila genetics, zebrafish in vivo), replicated across species","pmids":["22240901"],"is_preprint":false},{"year":2011,"finding":"TMBIM3/GRINA encodes an approximately 38 kDa transmembrane protein with a predicted seven-transmembrane domain topology, highly expressed in the brain including high levels in the hippocampus. A Tmbim3 knockout mouse did not display an obvious phenotype under basal conditions.","method":"Biochemical fractionation, sequence analysis, immunohistochemistry, knockout mouse generation","journal":"Molecular and cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical characterization and knockout mouse, single lab but multiple orthogonal methods","pmids":["21614515"],"is_preprint":false},{"year":2019,"finding":"GRINA deficiency in mice increases infarct volume after transient middle cerebral artery occlusion, worsens neurological deficits, and elevates cleaved caspase-3, pro-apoptotic BAX mRNA, and caspase-9 levels, indicating GRINA suppresses the caspase-9-dependent apoptotic pathway in ischemic neurons. EPO upregulates GRINA mRNA and its neuroprotection is abolished in GRINA-deficient mice.","method":"GRINA knockout mouse model, tMCAo focal ischemia model, primary cortical neuron oxygen-glucose deprivation, Western blotting, mRNA analysis, overexpression rescue experiments","journal":"Experimental neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout with defined phenotypic readout, rescue by overexpression, multiple orthogonal methods, replicated in vivo and in vitro","pmids":["31211943"],"is_preprint":false},{"year":2019,"finding":"GRINA is predominantly located at the ER membrane where it suppresses ER calcium release by inositol-1,4,5-trisphosphate receptors. GRINA deficiency increases activation of the pro-apoptotic PERK arm of the UPR after ischemic stroke. EPO enhances the pro-survival IRE1α arm and counteracts the pro-apoptotic PERK branch in a GRINA-dependent manner. PERK inhibition (GSK-2606414) reduces cell death and regulates Grina mRNA levels after OGD.","method":"GRINA-deficient mice, tMCAo model, OGD in primary cortical mixed cell cultures, pharmacological UPR inhibitors (GSK-2606414, STF-083010), Western blotting, mRNA analysis","journal":"International journal of molecular sciences","confidence":"High","confidence_rationale":"Tier 2 / Strong — knockout mouse with defined pathway placement, pharmacological validation, multiple orthogonal in vivo and in vitro methods","pmids":["31683519"],"is_preprint":false},{"year":2019,"finding":"GRINA/TMBIM3 directly interacts with CaV2.2 (N-type) voltage-gated calcium channels, confirmed by co-immunoprecipitation. Co-expression reduces CaV2.2 current amplitude, slows activation kinetics, and shifts voltage-dependency of activation time constants to more depolarized voltages. A strong depolarizing prepulse relieves the inhibition, mimicking the well-characterized modulatory mechanism of G-protein βγ subunits on CaV2 channels.","method":"Co-immunoprecipitation, whole-cell patch clamp electrophysiology, co-expression in heterologous system, action potential-like stimulus protocols","journal":"Cell calcium","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological reconstitution plus Co-IP, multiple functional parameters measured, single lab but multiple orthogonal methods","pmids":["30991297"],"is_preprint":false},{"year":2018,"finding":"GRINA is transcriptionally mediated by c-Myc in gastric cancer cells. GRINA knockdown decreases PI3K/Akt/mTOR signaling and glycolytic metabolism, promotes apoptosis, increases Bax expression, and decreases Bcl-2 expression.","method":"siRNA knockdown, Western blotting, glycolysis assays, cell proliferation and apoptosis assays, PI3K/Akt/mTOR pathway analysis, c-Myc transcriptional analysis","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined pathway readout (PI3K/Akt/mTOR and apoptosis), single lab, multiple assays","pmids":["30541591"],"is_preprint":false},{"year":2025,"finding":"GRINA directly interacts with ATF6 and recruits HRD1 to form a multiprotein GRINA-HRD1-ATF6 complex that catalyzes ATF6 polyubiquitination and promotes its proteasomal degradation. This suppresses ER autophagy (ER-phagy) and protects hepatocytes from ischemia-reperfusion injury. Inhibition of ATF6 degradation attenuates GRINA's protective effects.","method":"Coimmunoprecipitation, ubiquitination assays, mass spectrometry, hepatocyte-specific Grina knockout and transgenic mouse models, RNA sequencing, Western blotting, pharmacological ATF6 inhibition","journal":"Journal of hepatology","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical reconstitution of the complex, ubiquitination assay, in vivo KO and transgenic rescue, multiple orthogonal methods","pmids":["39855351"],"is_preprint":false},{"year":2025,"finding":"GRINA knockdown in HCC cells increases intracellular iron and reactive oxygen species (ROS) levels and causes mitochondrial abnormalities, indicating GRINA suppresses ferroptosis.","method":"siRNA knockdown, ROS assays, intracellular iron quantification, mitochondrial morphology analysis, cell proliferation and colony formation assays","journal":"Current medical science","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — loss-of-function with defined ferroptosis-related readouts, single lab, single method per endpoint","pmids":["40011365"],"is_preprint":false}],"current_model":"GRINA (TMBIM3) is a multi-transmembrane ER-membrane protein that controls apoptosis and ER stress responses by (1) physically interacting with IP3Rs to suppress ER calcium release, (2) forming a GRINA-HRD1-ATF6 complex that drives ATF6 polyubiquitination and degradation to restrain ER-phagy, (3) modulating voltage-gated CaV2.2 channels in a G-protein βγ-like inhibitory manner, and (4) being transcriptionally induced by the PERK branch of the UPR; loss of GRINA shifts UPR signaling toward the pro-apoptotic PERK arm and exacerbates caspase-9-dependent cell death in ischemic injury models."},"narrative":{"mechanistic_narrative":"GRINA (TMBIM3) is a multi-transmembrane ER-membrane protein that governs ER calcium homeostasis, the unfolded protein response, and apoptotic cell fate [PMID:22240901, PMID:31683519]. It is transcriptionally induced by the PERK branch of the UPR and limits ER calcium release through physical interaction with inositol-1,4,5-trisphosphate receptors, synergizing with TMBIM6/BI-1 to provide ER stress protection [PMID:22240901, PMID:31683519]. In ischemic injury, GRINA restrains the pro-apoptotic PERK arm of the UPR and suppresses caspase-9-dependent neuronal death; its loss enlarges infarct volume and abolishes erythropoietin-mediated neuroprotection [PMID:31211943, PMID:31683519]. GRINA also assembles a GRINA-HRD1-ATF6 complex that catalyzes ATF6 polyubiquitination and proteasomal degradation, thereby suppressing ER-phagy and protecting hepatocytes from ischemia-reperfusion injury [PMID:39855351]. Beyond the ER, GRINA directly binds CaV2.2 (N-type) voltage-gated calcium channels and inhibits their current in a manner mimicking G-protein βγ modulation [PMID:30991297]. In cancer cells GRINA supports PI3K/Akt/mTOR signaling and glycolytic metabolism and restrains apoptosis and ferroptosis [PMID:30541591, PMID:40011365].","teleology":[{"year":2011,"claim":"Established GRINA as a defined gene product by characterizing it as an ~38 kDa seven-transmembrane protein enriched in brain, providing the structural and expression baseline for later functional studies.","evidence":"Biochemical fractionation, sequence analysis, immunohistochemistry, and knockout mouse generation","pmids":["21614515"],"confidence":"Medium","gaps":["No molecular function assigned at this stage","Basal knockout had no obvious phenotype, leaving physiological role undefined","Topology was predicted, not structurally resolved"]},{"year":2012,"claim":"Placed GRINA within ER stress biology by showing it is induced via the PERK arm of the UPR and physically engages IP3Rs to control ER calcium and apoptosis, defining its core ER-protective function.","evidence":"Reciprocal Co-IP for IP3R interaction plus loss-of-function in Drosophila and zebrafish and calcium homeostasis assays","pmids":["22240901"],"confidence":"High","gaps":["Mechanism by which GRINA suppresses IP3R-mediated calcium release not resolved at molecular level","Relationship between PERK induction and downstream survival not yet defined","No mammalian disease context established"]},{"year":2019,"claim":"Demonstrated GRINA directly inhibits CaV2.2 voltage-gated calcium channels, extending its calcium-regulatory role to the plasma-membrane channel level.","evidence":"Co-IP and whole-cell patch clamp electrophysiology in a heterologous co-expression system with action-potential-like protocols","pmids":["30991297"],"confidence":"High","gaps":["Whether GRINA modulates CaV2.2 in native neurons not shown","Structural basis of the βγ-like inhibition unknown","Physiological consequence of channel inhibition not established in vivo"]},{"year":2019,"claim":"Defined GRINA's neuroprotective function in vivo by showing its loss exacerbates ischemic stroke through derepression of the caspase-9 apoptotic pathway and the pro-apoptotic PERK arm of the UPR, linking it to EPO-mediated survival signaling.","evidence":"GRINA knockout mice in tMCAo focal ischemia, primary neuron OGD, pharmacological UPR inhibitors, overexpression rescue, Western blotting, and mRNA analysis","pmids":["31211943","31683519"],"confidence":"High","gaps":["How GRINA biases UPR signaling away from PERK and toward IRE1α mechanistically unresolved","Direct molecular link between GRINA and caspase-9 not defined","EPO-to-GRINA induction pathway not mapped"]},{"year":2018,"claim":"Connected GRINA to oncogenic metabolism by showing it is a c-Myc transcriptional target supporting PI3K/Akt/mTOR signaling, glycolysis, and apoptosis resistance in gastric cancer.","evidence":"siRNA knockdown with glycolysis, proliferation, apoptosis assays and pathway/transcriptional analysis","pmids":["30541591"],"confidence":"Medium","gaps":["Single-lab, single cancer type","Mechanism linking GRINA to PI3K/Akt/mTOR not defined","No direct molecular interaction with pathway components shown"]},{"year":2025,"claim":"Revealed a new biochemical mechanism: GRINA scaffolds a HRD1-ATF6 complex to drive ATF6 polyubiquitination and degradation, suppressing ER-phagy and protecting hepatocytes from ischemia-reperfusion injury.","evidence":"Co-IP, ubiquitination assays, mass spectrometry, hepatocyte-specific Grina knockout and transgenic mice, RNA-seq, and pharmacological ATF6 inhibition","pmids":["39855351"],"confidence":"High","gaps":["How GRINA recruits HRD1 to ATF6 structurally unknown","Whether this complex operates outside hepatocytes not established","Integration with the IP3R/PERK functions not resolved"]},{"year":2025,"claim":"Extended GRINA's anti-death function to ferroptosis by showing its knockdown raises iron and ROS and causes mitochondrial abnormalities in HCC cells.","evidence":"siRNA knockdown with ROS assays, iron quantification, mitochondrial morphology, and proliferation/colony formation assays","pmids":["40011365"],"confidence":"Medium","gaps":["Single-lab, single endpoint per readout","Molecular mechanism of ferroptosis suppression unknown","Link to GRINA's ER calcium/UPR functions not made"]},{"year":null,"claim":"How GRINA's distinct activities — IP3R/CaV2.2 channel modulation, UPR arm biasing, and HRD1-ATF6-mediated ER-phagy control — are integrated into a single coherent molecular mechanism remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural model unifying its transmembrane topology with its multiple binding partners","Unclear whether channel modulation and ATF6 degradation occur in the same cellular context","Relative contribution of each activity to cytoprotection not quantified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,3,4]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[4]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0,3]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[2,5,7]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[6]}],"complexes":["GRINA-HRD1-ATF6 complex"],"partners":["ITPR1","CACNA1B","ATF6","SYVN1","TMBIM6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q7Z429","full_name":"Protein lifeguard 1","aliases":["Glutamate [NMDA] receptor-associated protein 1","NMDA receptor glutamate-binding subunit","Putative MAPK-activating protein PM02","Transmembrane BAX inhibitor motif-containing protein 3"],"length_aa":371,"mass_kda":41.2,"function":"Potential apoptotic regulator","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q7Z429/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GRINA","classification":"Not Classified","n_dependent_lines":10,"n_total_lines":1208,"dependency_fraction":0.008278145695364239},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GRINA","total_profiled":1310},"omim":[{"mim_id":"138251","title":"GLUTAMATE RECEPTOR, IONOTROPIC, N-METHYL-D-ASPARTATE, ASSOCIATED PROTEIN; GRINA","url":"https://www.omim.org/entry/138251"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli fibrillar center","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GRINA"},"hgnc":{"alias_symbol":["HNRGW","TMBIM3","LFG1"],"prev_symbol":["NMDARA1"]},"alphafold":{"accession":"Q7Z429","domains":[{"cath_id":"-","chopping":"155-369","consensus_level":"medium","plddt":89.326,"start":155,"end":369}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z429","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z429-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z429-F1-predicted_aligned_error_v6.png","plddt_mean":71.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GRINA","jax_strain_url":"https://www.jax.org/strain/search?query=GRINA"},"sequence":{"accession":"Q7Z429","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7Z429.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7Z429/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z429"}},"corpus_meta":[{"pmid":"22240901","id":"PMC_22240901","title":"TMBIM3/GRINA is a novel unfolded protein response (UPR) target gene that controls apoptosis through the modulation of ER calcium homeostasis.","date":"2012","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/22240901","citation_count":70,"is_preprint":false},{"pmid":"30730609","id":"PMC_30730609","title":"Prioritization of PLEC and GRINA as Osteoarthritis Risk Genes Through the Identification and Characterization of Novel Methylation Quantitative Trait Loci.","date":"2019","source":"Arthritis & rheumatology (Hoboken, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/30730609","citation_count":44,"is_preprint":false},{"pmid":"30541591","id":"PMC_30541591","title":"Transmembrane protein GRINA modulates aerobic glycolysis and promotes tumor progression in gastric cancer.","date":"2018","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/30541591","citation_count":29,"is_preprint":false},{"pmid":"31211943","id":"PMC_31211943","title":"EPO regulates neuroprotective Transmembrane BAX Inhibitor-1 Motif-containing (TMBIM) family members GRINA and FAIM2 after cerebral ischemia-reperfusion injury.","date":"2019","source":"Experimental neurology","url":"https://pubmed.ncbi.nlm.nih.gov/31211943","citation_count":20,"is_preprint":false},{"pmid":"30685393","id":"PMC_30685393","title":"Gut permeability and mimicry of the Glutamate Ionotropic Receptor NMDA type Subunit Associated with protein 1 (GRINA) as potential mechanisms related to a subgroup of people with schizophrenia with elevated antigliadin antibodies (AGA IgG).","date":"2019","source":"Schizophrenia research","url":"https://pubmed.ncbi.nlm.nih.gov/30685393","citation_count":18,"is_preprint":false},{"pmid":"21614515","id":"PMC_21614515","title":"Mouse transmembrane BAX inhibitor motif 3 (Tmbim3) encodes a 38 kDa transmembrane protein expressed in the central nervous system.","date":"2011","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21614515","citation_count":18,"is_preprint":false},{"pmid":"31683519","id":"PMC_31683519","title":"EPO and TMBIM3/GRINA Promote the Activation of the Adaptive Arm and Counteract the Terminal Arm of the Unfolded Protein Response after Murine Transient Cerebral Ischemia.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31683519","citation_count":17,"is_preprint":false},{"pmid":"8406459","id":"PMC_8406459","title":"Mapping of the human NMDA receptor subunit (NMDAR1) and the proposed NMDA receptor glutamate-binding subunit (NMDARA1) to chromosomes 9q34.3 and chromosome 8, respectively.","date":"1993","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8406459","citation_count":17,"is_preprint":false},{"pmid":"8786101","id":"PMC_8786101","title":"Localization of a gene for a glutamate binding subunit of a NMDA receptor (GRINA) to 8q24.","date":"1996","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8786101","citation_count":16,"is_preprint":false},{"pmid":"31426446","id":"PMC_31426446","title":"Deciphering GRINA/Lifeguard1: Nuclear Location, Ca2+ Homeostasis and Vesicle Transport.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31426446","citation_count":15,"is_preprint":false},{"pmid":"39855351","id":"PMC_39855351","title":"GRINA alleviates hepatic ischemia‒reperfusion injury-induced apoptosis and ER-phagy by enhancing HRD1-mediated ATF6 ubiquitination.","date":"2025","source":"Journal of hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/39855351","citation_count":14,"is_preprint":false},{"pmid":"32124700","id":"PMC_32124700","title":"Role of Grina/Nmdara1 in the Central Nervous System Diseases.","date":"2020","source":"Current neuropharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/32124700","citation_count":14,"is_preprint":false},{"pmid":"7711078","id":"PMC_7711078","title":"The putative Drosophila NMDARA1 gene is located on the second chromosome and is ubiquitously expressed in embryogenesis.","date":"1995","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/7711078","citation_count":12,"is_preprint":false},{"pmid":"30991297","id":"PMC_30991297","title":"Grina/TMBIM3 modulates voltage-gated CaV2.2 Ca2+ channels in a G-protein-like manner.","date":"2019","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/30991297","citation_count":6,"is_preprint":false},{"pmid":"40011365","id":"PMC_40011365","title":"Cellular Membrane Protein GRINA is Highly Expressed and Associated with Survival Outcomes in Liver Cancer Patients.","date":"2025","source":"Current medical science","url":"https://pubmed.ncbi.nlm.nih.gov/40011365","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9614,"output_tokens":2233,"usd":0.031168,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9325,"output_tokens":3057,"usd":0.061525,"stage2_stop_reason":"end_turn"},"total_usd":0.092693,"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\": 2012,\n      \"finding\": \"TMBIM3/GRINA is transcriptionally upregulated by ER stress via the PERK signaling branch of the unfolded protein response. TMBIM3/GRINA modulates ER calcium homeostasis and apoptosis through physical interaction with inositol trisphosphate receptors (IP3Rs). It synergizes with TMBIM6/BI-1 in ER stress protection in vivo (Drosophila and zebrafish models).\",\n      \"method\": \"Co-immunoprecipitation (physical interaction with IP3Rs), loss-of-function studies in Drosophila and zebrafish, PERK branch manipulation, calcium homeostasis assays\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP for IP3R interaction, multiple orthogonal methods (biochemical, Drosophila genetics, zebrafish in vivo), replicated across species\",\n      \"pmids\": [\"22240901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"TMBIM3/GRINA encodes an approximately 38 kDa transmembrane protein with a predicted seven-transmembrane domain topology, highly expressed in the brain including high levels in the hippocampus. A Tmbim3 knockout mouse did not display an obvious phenotype under basal conditions.\",\n      \"method\": \"Biochemical fractionation, sequence analysis, immunohistochemistry, knockout mouse generation\",\n      \"journal\": \"Molecular and cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical characterization and knockout mouse, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"21614515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GRINA deficiency in mice increases infarct volume after transient middle cerebral artery occlusion, worsens neurological deficits, and elevates cleaved caspase-3, pro-apoptotic BAX mRNA, and caspase-9 levels, indicating GRINA suppresses the caspase-9-dependent apoptotic pathway in ischemic neurons. EPO upregulates GRINA mRNA and its neuroprotection is abolished in GRINA-deficient mice.\",\n      \"method\": \"GRINA knockout mouse model, tMCAo focal ischemia model, primary cortical neuron oxygen-glucose deprivation, Western blotting, mRNA analysis, overexpression rescue experiments\",\n      \"journal\": \"Experimental neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout with defined phenotypic readout, rescue by overexpression, multiple orthogonal methods, replicated in vivo and in vitro\",\n      \"pmids\": [\"31211943\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GRINA is predominantly located at the ER membrane where it suppresses ER calcium release by inositol-1,4,5-trisphosphate receptors. GRINA deficiency increases activation of the pro-apoptotic PERK arm of the UPR after ischemic stroke. EPO enhances the pro-survival IRE1α arm and counteracts the pro-apoptotic PERK branch in a GRINA-dependent manner. PERK inhibition (GSK-2606414) reduces cell death and regulates Grina mRNA levels after OGD.\",\n      \"method\": \"GRINA-deficient mice, tMCAo model, OGD in primary cortical mixed cell cultures, pharmacological UPR inhibitors (GSK-2606414, STF-083010), Western blotting, mRNA analysis\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knockout mouse with defined pathway placement, pharmacological validation, multiple orthogonal in vivo and in vitro methods\",\n      \"pmids\": [\"31683519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GRINA/TMBIM3 directly interacts with CaV2.2 (N-type) voltage-gated calcium channels, confirmed by co-immunoprecipitation. Co-expression reduces CaV2.2 current amplitude, slows activation kinetics, and shifts voltage-dependency of activation time constants to more depolarized voltages. A strong depolarizing prepulse relieves the inhibition, mimicking the well-characterized modulatory mechanism of G-protein βγ subunits on CaV2 channels.\",\n      \"method\": \"Co-immunoprecipitation, whole-cell patch clamp electrophysiology, co-expression in heterologous system, action potential-like stimulus protocols\",\n      \"journal\": \"Cell calcium\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological reconstitution plus Co-IP, multiple functional parameters measured, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"30991297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"GRINA is transcriptionally mediated by c-Myc in gastric cancer cells. GRINA knockdown decreases PI3K/Akt/mTOR signaling and glycolytic metabolism, promotes apoptosis, increases Bax expression, and decreases Bcl-2 expression.\",\n      \"method\": \"siRNA knockdown, Western blotting, glycolysis assays, cell proliferation and apoptosis assays, PI3K/Akt/mTOR pathway analysis, c-Myc transcriptional analysis\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined pathway readout (PI3K/Akt/mTOR and apoptosis), single lab, multiple assays\",\n      \"pmids\": [\"30541591\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GRINA directly interacts with ATF6 and recruits HRD1 to form a multiprotein GRINA-HRD1-ATF6 complex that catalyzes ATF6 polyubiquitination and promotes its proteasomal degradation. This suppresses ER autophagy (ER-phagy) and protects hepatocytes from ischemia-reperfusion injury. Inhibition of ATF6 degradation attenuates GRINA's protective effects.\",\n      \"method\": \"Coimmunoprecipitation, ubiquitination assays, mass spectrometry, hepatocyte-specific Grina knockout and transgenic mouse models, RNA sequencing, Western blotting, pharmacological ATF6 inhibition\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical reconstitution of the complex, ubiquitination assay, in vivo KO and transgenic rescue, multiple orthogonal methods\",\n      \"pmids\": [\"39855351\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GRINA knockdown in HCC cells increases intracellular iron and reactive oxygen species (ROS) levels and causes mitochondrial abnormalities, indicating GRINA suppresses ferroptosis.\",\n      \"method\": \"siRNA knockdown, ROS assays, intracellular iron quantification, mitochondrial morphology analysis, cell proliferation and colony formation assays\",\n      \"journal\": \"Current medical science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — loss-of-function with defined ferroptosis-related readouts, single lab, single method per endpoint\",\n      \"pmids\": [\"40011365\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GRINA (TMBIM3) is a multi-transmembrane ER-membrane protein that controls apoptosis and ER stress responses by (1) physically interacting with IP3Rs to suppress ER calcium release, (2) forming a GRINA-HRD1-ATF6 complex that drives ATF6 polyubiquitination and degradation to restrain ER-phagy, (3) modulating voltage-gated CaV2.2 channels in a G-protein βγ-like inhibitory manner, and (4) being transcriptionally induced by the PERK branch of the UPR; loss of GRINA shifts UPR signaling toward the pro-apoptotic PERK arm and exacerbates caspase-9-dependent cell death in ischemic injury models.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GRINA (TMBIM3) is a multi-transmembrane ER-membrane protein that governs ER calcium homeostasis, the unfolded protein response, and apoptotic cell fate [#0, #3]. It is transcriptionally induced by the PERK branch of the UPR and limits ER calcium release through physical interaction with inositol-1,4,5-trisphosphate receptors, synergizing with TMBIM6/BI-1 to provide ER stress protection [#0, #3]. In ischemic injury, GRINA restrains the pro-apoptotic PERK arm of the UPR and suppresses caspase-9-dependent neuronal death; its loss enlarges infarct volume and abolishes erythropoietin-mediated neuroprotection [#2, #3]. GRINA also assembles a GRINA-HRD1-ATF6 complex that catalyzes ATF6 polyubiquitination and proteasomal degradation, thereby suppressing ER-phagy and protecting hepatocytes from ischemia-reperfusion injury [#6]. Beyond the ER, GRINA directly binds CaV2.2 (N-type) voltage-gated calcium channels and inhibits their current in a manner mimicking G-protein βγ modulation [#4]. In cancer cells GRINA supports PI3K/Akt/mTOR signaling and glycolytic metabolism and restrains apoptosis and ferroptosis [#5, #7].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Established GRINA as a defined gene product by characterizing it as an ~38 kDa seven-transmembrane protein enriched in brain, providing the structural and expression baseline for later functional studies.\",\n      \"evidence\": \"Biochemical fractionation, sequence analysis, immunohistochemistry, and knockout mouse generation\",\n      \"pmids\": [\"21614515\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No molecular function assigned at this stage\", \"Basal knockout had no obvious phenotype, leaving physiological role undefined\", \"Topology was predicted, not structurally resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed GRINA within ER stress biology by showing it is induced via the PERK arm of the UPR and physically engages IP3Rs to control ER calcium and apoptosis, defining its core ER-protective function.\",\n      \"evidence\": \"Reciprocal Co-IP for IP3R interaction plus loss-of-function in Drosophila and zebrafish and calcium homeostasis assays\",\n      \"pmids\": [\"22240901\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Mechanism by which GRINA suppresses IP3R-mediated calcium release not resolved at molecular level\", \"Relationship between PERK induction and downstream survival not yet defined\", \"No mammalian disease context established\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated GRINA directly inhibits CaV2.2 voltage-gated calcium channels, extending its calcium-regulatory role to the plasma-membrane channel level.\",\n      \"evidence\": \"Co-IP and whole-cell patch clamp electrophysiology in a heterologous co-expression system with action-potential-like protocols\",\n      \"pmids\": [\"30991297\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether GRINA modulates CaV2.2 in native neurons not shown\", \"Structural basis of the βγ-like inhibition unknown\", \"Physiological consequence of channel inhibition not established in vivo\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined GRINA's neuroprotective function in vivo by showing its loss exacerbates ischemic stroke through derepression of the caspase-9 apoptotic pathway and the pro-apoptotic PERK arm of the UPR, linking it to EPO-mediated survival signaling.\",\n      \"evidence\": \"GRINA knockout mice in tMCAo focal ischemia, primary neuron OGD, pharmacological UPR inhibitors, overexpression rescue, Western blotting, and mRNA analysis\",\n      \"pmids\": [\"31211943\", \"31683519\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How GRINA biases UPR signaling away from PERK and toward IRE1α mechanistically unresolved\", \"Direct molecular link between GRINA and caspase-9 not defined\", \"EPO-to-GRINA induction pathway not mapped\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected GRINA to oncogenic metabolism by showing it is a c-Myc transcriptional target supporting PI3K/Akt/mTOR signaling, glycolysis, and apoptosis resistance in gastric cancer.\",\n      \"evidence\": \"siRNA knockdown with glycolysis, proliferation, apoptosis assays and pathway/transcriptional analysis\",\n      \"pmids\": [\"30541591\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single-lab, single cancer type\", \"Mechanism linking GRINA to PI3K/Akt/mTOR not defined\", \"No direct molecular interaction with pathway components shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealed a new biochemical mechanism: GRINA scaffolds a HRD1-ATF6 complex to drive ATF6 polyubiquitination and degradation, suppressing ER-phagy and protecting hepatocytes from ischemia-reperfusion injury.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, mass spectrometry, hepatocyte-specific Grina knockout and transgenic mice, RNA-seq, and pharmacological ATF6 inhibition\",\n      \"pmids\": [\"39855351\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How GRINA recruits HRD1 to ATF6 structurally unknown\", \"Whether this complex operates outside hepatocytes not established\", \"Integration with the IP3R/PERK functions not resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended GRINA's anti-death function to ferroptosis by showing its knockdown raises iron and ROS and causes mitochondrial abnormalities in HCC cells.\",\n      \"evidence\": \"siRNA knockdown with ROS assays, iron quantification, mitochondrial morphology, and proliferation/colony formation assays\",\n      \"pmids\": [\"40011365\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single-lab, single endpoint per readout\", \"Molecular mechanism of ferroptosis suppression unknown\", \"Link to GRINA's ER calcium/UPR functions not made\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How GRINA's distinct activities — IP3R/CaV2.2 channel modulation, UPR arm biasing, and HRD1-ATF6-mediated ER-phagy control — are integrated into a single coherent molecular mechanism remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No structural model unifying its transmembrane topology with its multiple binding partners\", \"Unclear whether channel modulation and ATF6 degradation occur in the same cellular context\", \"Relative contribution of each activity to cytoprotection not quantified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 3, 4]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [2, 5, 7]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\"GRINA-HRD1-ATF6 complex\"],\n    \"partners\": [\"ITPR1\", \"CACNA1B\", \"ATF6\", \"SYVN1\", \"TMBIM6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":6,"faith_total":6,"faith_pct":100.0}}