{"gene":"RASGEF1B","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2009,"finding":"RasGEF1B functions as a highly specific guanine nucleotide exchange factor (GEF) for Rap2, a member of the Rap subfamily of Ras-like G-proteins, but does not act on Rap1 or other Ras subfamily members. Reciprocal site-directed mutagenesis identified Phe39 in the switch I region of Rap2 as the specificity determinant; mutating the corresponding Ser39 in Rap1 to Phe (Rap1-S39F) allowed RasGEF1B to stimulate nucleotide exchange on Rap1.","method":"In vitro nucleotide exchange assays with purified RasGEF1B and Ras-family proteins; reciprocal site-directed mutagenesis of Rap1/Rap2 switch I residues","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified proteins plus mutagenesis identifying specificity residue, multiple orthogonal approaches in one study","pmids":["19645719"],"is_preprint":false},{"year":2010,"finding":"RasGEF1B localizes to early endosomes when ectopically expressed in HEK293T cells (found predominantly in the heavy membrane fraction by fractionation and confirmed at early endosomes by confocal microscopy). RasGEF1B was found in close association with Ras in live cells and triggered Ras GTPase activity, indicating it can activate Ras-like proteins at early endosomes. In macrophages, TLR3 (poly I:C) and TLR4 (LPS) induce RasGEF1B expression through the MyD88-independent (TRIF) pathway.","method":"Subcellular fractionation, confocal microscopy co-localization, live-cell Ras activity assay; in vivo infection models with MyD88/TRIF knockout macrophages","journal":"Genes and immunity","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct localization by fractionation and confocal microscopy with functional Ras activation assay, single lab, multiple orthogonal methods","pmids":["20090772"],"is_preprint":false},{"year":2020,"finding":"TLR-induced transcription of Rasgef1b in macrophages is driven by NF-κB acting through a proximal promoter region (-183 to +119) that contains a cluster of five NF-κB binding sites. Site-directed mutagenesis of these κB sites reduced maximal LPS-induced promoter activation. ChIP-seq showed RelA (p65) is recruited to this promoter region upon LPS stimulation. Rela-deficient macrophages or pharmacological NF-κB inhibition (Bay11-7082) reduced optimal Rasgef1b expression, and luciferase reporter assays showed RelA and cRel (but not RelB) activate the promoter.","method":"Luciferase reporter assay, site-directed mutagenesis of κB sites, ATAC-seq, ChIP-seq, Rela-deficient macrophages, pharmacological inhibition","journal":"The international journal of biochemistry & cell biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (reporter assay, mutagenesis, ChIP-seq, KO cells) in a single rigorous study establishing the transcriptional regulatory mechanism","pmids":["32866686"],"is_preprint":false},{"year":2023,"finding":"Deletion of Rasgef1b in mice alters basal and LPS-induced expression of genes involved in chemotaxis, cytokine responses, and GTPase activity regulation in macrophages. RasGEF1b knockdown in RAW264.7 macrophages impaired transcriptional activation of the Serpinb2 promoter both under constitutive and LPS-stimulated conditions, as demonstrated by luciferase reporter assay.","method":"RNA-seq transcriptomics in wild-type vs. Rasgef1b-knockout bone marrow-derived macrophages; RT-qPCR validation; luciferase-based Serpinb2 promoter assay with RasGEF1b knockdown","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNA-seq plus targeted promoter assay with knockdown, single lab, two orthogonal approaches","pmids":["37950057"],"is_preprint":false},{"year":2023,"finding":"RasGEF1b deficiency in mice leads to behavioral abnormalities (hyperlocomotion, anhedonia, compulsive-like behavior reversible by fluoxetine), downregulation of dopamine receptor (Drd1, Drd2, Drd4, Drd5) and serotonin receptor (5Htr1a, 5Htr1b, 5Htr1d) mRNAs in hippocampus and prefrontal cortex, morphological alterations in microglia, and decreased hippocampal BDNF levels.","method":"Conditional knockout mouse model; behavioral tests; RT-qPCR for receptor mRNAs; microglia morphological analysis; BDNF protein quantification","journal":"Progress in neuro-psychopharmacology & biological psychiatry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined genetic KO with multiple phenotypic readouts, single lab, orthogonal methods but no direct mechanistic link to GEF activity","pmids":["38048936"],"is_preprint":false},{"year":2026,"finding":"RASGEF1B suppresses hepatocellular carcinoma through a metabolic–epigenetic axis: RASGEF1B competitively protects ALDH7A1 protein from BMI1-dependent ubiquitination (confirmed by co-immunoprecipitation, GST pull-down, and in vitro reconstituted ubiquitination assay), thereby elevating cellular betaine levels. Elevated betaine promotes SNAI1 DNA methylation via methionine metabolic reprogramming, reducing SNAI1 expression and suppressing epithelial-mesenchymal transition and HCC progression.","method":"Co-immunoprecipitation, GST pull-down, immunofluorescence, in vitro reconstituted ubiquitination system, cycloheximide chase, methylation-specific PCR, luciferase reporter assay, transcriptome sequencing, untargeted metabolomics, in vitro and in vivo tumor models","journal":"Journal of translational medicine","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal biochemical methods (GST pull-down, in vitro ubiquitination reconstitution, Co-IP) combined with metabolomics and epigenetic assays in a single rigorous study","pmids":["41742192"],"is_preprint":false}],"current_model":"RASGEF1B is a highly specific guanine nucleotide exchange factor for Rap2 (not Rap1 or other Ras GTPases), localizes to early endosomes upon TLR activation, and is transcriptionally induced in macrophages via NF-κB (RelA/cRel) binding to a proximal promoter; beyond canonical GEF activity, RASGEF1B also suppresses hepatocellular carcinoma by protecting ALDH7A1 from BMI1-mediated ubiquitination, thereby elevating betaine and promoting SNAI1 DNA methylation to inhibit epithelial-mesenchymal transition, and its loss in mice disrupts macrophage gene regulation and causes neurochemical and behavioral abnormalities."},"narrative":{"mechanistic_narrative":"RASGEF1B is a guanine nucleotide exchange factor that links innate immune signaling to small-GTPase activation and, independently, restrains tumor progression through a metabolic-epigenetic axis [PMID:19645719, PMID:41742192]. As a GEF it is highly specific for the Rap-subfamily GTPase Rap2 and does not act on Rap1 or other Ras-family members, with Phe39 in the Rap2 switch I region serving as the specificity determinant [PMID:19645719]. The protein localizes to early endosomes, where it associates with and activates Ras-like proteins, and its expression is induced in macrophages downstream of TLR3 and TLR4 via the TRIF (MyD88-independent) pathway [PMID:20090772]. This induction is driven transcriptionally by NF-κB: RelA and cRel are recruited to a proximal promoter cluster of κB sites to activate Rasgef1b in response to LPS [PMID:32866686]. Loss of Rasgef1b in mice reshapes macrophage transcriptional programs governing chemotaxis, cytokine responses, and GTPase regulation, and produces neurochemical and behavioral abnormalities including altered dopamine/serotonin receptor expression and reduced hippocampal BDNF [PMID:37950057, PMID:38048936]. In hepatocellular carcinoma, RASGEF1B competitively protects ALDH7A1 from BMI1-mediated ubiquitination, raising betaine levels that promote SNAI1 DNA methylation and thereby suppress epithelial-mesenchymal transition [PMID:41742192].","teleology":[{"year":2009,"claim":"Established the core enzymatic identity of RASGEF1B by defining its substrate specificity, answering whether it is a general Ras GEF or a selective one.","evidence":"In vitro nucleotide exchange assays with purified proteins plus reciprocal switch I mutagenesis of Rap1/Rap2","pmids":["19645719"],"confidence":"High","gaps":["Physiological context in which Rap2 activation by RASGEF1B occurs not addressed","Regulation of GEF activity (autoinhibition, recruitment) not characterized"]},{"year":2010,"claim":"Connected the GEF to a subcellular site and an immune signaling input, showing where it acts and how its expression is triggered.","evidence":"Subcellular fractionation and confocal co-localization in HEK293T, live-cell Ras activity assay, and MyD88/TRIF knockout macrophage infection models","pmids":["20090772"],"confidence":"Medium","gaps":["Localization shown for ectopically expressed protein, not endogenous","Ras activation observed but reconciliation with Rap2-specific in vitro activity unresolved"]},{"year":2020,"claim":"Defined the transcriptional mechanism of TLR-induced expression, identifying the specific factors and promoter elements driving induction.","evidence":"Luciferase reporters, κB-site mutagenesis, ATAC-seq, ChIP-seq, Rela-deficient macrophages, and pharmacological NF-κB inhibition","pmids":["32866686"],"confidence":"High","gaps":["Downstream consequences of induced RASGEF1B on macrophage GTPase signaling not traced","Relative contributions of RelA versus cRel in vivo not resolved"]},{"year":2023,"claim":"Tested the organism-level requirement for RASGEF1B, revealing its impact on macrophage gene regulation and a specific promoter target.","evidence":"RNA-seq of wild-type vs. knockout BMDMs with RT-qPCR validation and Serpinb2 promoter luciferase assay under knockdown","pmids":["37950057"],"confidence":"Medium","gaps":["Mechanism linking GEF activity to Serpinb2 promoter regulation not defined","Direct versus indirect transcriptional effects not separated"]},{"year":2023,"claim":"Extended the phenotypic role of RASGEF1B beyond immunity to the nervous system, documenting behavioral and neurochemical consequences of its loss.","evidence":"Conditional knockout mouse with behavioral testing, RT-qPCR of neurotransmitter receptors, microglial morphometry, and BDNF quantification","pmids":["38048936"],"confidence":"Medium","gaps":["No direct mechanistic link from GEF/Rap2 activity to neurochemical phenotypes","Cell-type origin of behavioral defects (neuronal vs. microglial) not resolved"]},{"year":2026,"claim":"Uncovered a non-canonical tumor-suppressive function, showing RASGEF1B operates through protein stabilization and metabolic reprogramming rather than its GEF activity.","evidence":"Co-IP, GST pull-down, in vitro reconstituted ubiquitination, cycloheximide chase, methylation-specific PCR, metabolomics, and in vitro/in vivo HCC models","pmids":["41742192"],"confidence":"High","gaps":["Whether GEF/Rap2 activity contributes to ALDH7A1 protection not determined","Structural basis of competition with BMI1 for ALDH7A1 not defined"]},{"year":null,"claim":"How RASGEF1B's Rap2-specific GEF activity, endosomal localization, and tumor-suppressive ALDH7A1-stabilizing function mechanistically integrate within a single protein remains unresolved.","evidence":"No single study links the enzymatic, immune, and metabolic-epigenetic roles","pmids":[],"confidence":"Low","gaps":["No unifying mechanism connecting GEF activity to ALDH7A1 stabilization","Endogenous interactome and structure not characterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1,2,3]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1]}],"complexes":[],"partners":["RAP2","ALDH7A1","BMI1","RELA"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q0VAM2","full_name":"Ras-GEF domain-containing family member 1B","aliases":["GPI gamma-4"],"length_aa":473,"mass_kda":55.4,"function":"Guanine nucleotide exchange factor (GEF) with specificity for RAP2A, it doesn't seems to activate other Ras family proteins (in vitro)","subcellular_location":"Early endosome; Late endosome; Midbody","url":"https://www.uniprot.org/uniprotkb/Q0VAM2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RASGEF1B","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RASGEF1B","total_profiled":1310},"omim":[{"mim_id":"621286","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 124; CCDC124","url":"https://www.omim.org/entry/621286"},{"mim_id":"614532","title":"RASGEF DOMAIN FAMILY, MEMBER 1B; RASGEF1B","url":"https://www.omim.org/entry/614532"},{"mim_id":"614531","title":"RASGEF DOMAIN FAMILY, MEMBER 1A; RASGEF1A","url":"https://www.omim.org/entry/614531"},{"mim_id":"613509","title":"CHROMOSOME 4q21 DELETION SYNDROME","url":"https://www.omim.org/entry/613509"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"liver","ntpm":39.0}],"url":"https://www.proteinatlas.org/search/RASGEF1B"},"hgnc":{"alias_symbol":["GPIG4","FLJ31695"],"prev_symbol":[]},"alphafold":{"accession":"Q0VAM2","domains":[{"cath_id":"1.20.870.10","chopping":"26-159","consensus_level":"medium","plddt":87.8501,"start":26,"end":159},{"cath_id":"1.10.840.10","chopping":"199-234_252-469","consensus_level":"medium","plddt":94.8517,"start":199,"end":469}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VAM2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VAM2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VAM2-F1-predicted_aligned_error_v6.png","plddt_mean":87.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RASGEF1B","jax_strain_url":"https://www.jax.org/strain/search?query=RASGEF1B"},"sequence":{"accession":"Q0VAM2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q0VAM2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q0VAM2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VAM2"}},"corpus_meta":[{"pmid":"27362560","id":"PMC_27362560","title":"Inducible RasGEF1B circular RNA is a positive regulator of ICAM-1 in the TLR4/LPS pathway.","date":"2016","source":"RNA biology","url":"https://pubmed.ncbi.nlm.nih.gov/27362560","citation_count":135,"is_preprint":false},{"pmid":"28947785","id":"PMC_28947785","title":"Transcriptomic analysis of the role of RasGEF1B circular RNA in the TLR4/LPS pathway.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28947785","citation_count":34,"is_preprint":false},{"pmid":"19645719","id":"PMC_19645719","title":"RasGEF1A and RasGEF1B are guanine nucleotide exchange factors that discriminate between Rap GTP-binding proteins and mediate Rap2-specific nucleotide exchange.","date":"2009","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/19645719","citation_count":29,"is_preprint":false},{"pmid":"20090772","id":"PMC_20090772","title":"Early endosome localization and activity of RasGEF1b, a toll-like receptor-inducible Ras guanine-nucleotide exchange factor.","date":"2010","source":"Genes and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/20090772","citation_count":23,"is_preprint":false},{"pmid":"17239665","id":"PMC_17239665","title":"Expression of rasgef1b in zebrafish.","date":"2006","source":"Gene expression patterns : GEP","url":"https://pubmed.ncbi.nlm.nih.gov/17239665","citation_count":20,"is_preprint":false},{"pmid":"37099250","id":"PMC_37099250","title":"Aberrant expression of circular RNA DHPR facilitates tumor growth and metastasis by regulating the RASGEF1B/RAS/MAPK axis in hepatocellular carcinoma.","date":"2023","source":"Cellular oncology (Dordrecht, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/37099250","citation_count":14,"is_preprint":false},{"pmid":"32866686","id":"PMC_32866686","title":"Toll-like Receptor (TLR)-induced Rasgef1b expression in macrophages is regulated by NF-κB through its proximal promoter.","date":"2020","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/32866686","citation_count":13,"is_preprint":false},{"pmid":"34438395","id":"PMC_34438395","title":"Circ_RASGEF1B Promotes LPS-Induced Apoptosis and Inflammatory Response by Targeting MicroRNA-146a-5p/Pdk1 Axis in Septic Acute Kidney Injury Cell Model.","date":"2021","source":"Nephron","url":"https://pubmed.ncbi.nlm.nih.gov/34438395","citation_count":11,"is_preprint":false},{"pmid":"37950057","id":"PMC_37950057","title":"Transcriptomic analysis reveals that RasGEF1b deletion alters basal and LPS-induced expression of genes involved in chemotaxis and cytokine responses in macrophages.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/37950057","citation_count":4,"is_preprint":false},{"pmid":"38048936","id":"PMC_38048936","title":"Behavioral, neurochemical and neuroimmune features of RasGEF1b deficient mice.","date":"2023","source":"Progress in neuro-psychopharmacology & biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/38048936","citation_count":3,"is_preprint":false},{"pmid":"41742192","id":"PMC_41742192","title":"RASGEF1B suppresses hepatocellular carcinoma through the ALDH7A1/Betaine/SNAI1 metabolic‒epigenetic axis.","date":"2026","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41742192","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8053,"output_tokens":2086,"usd":0.027724,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9026,"output_tokens":2518,"usd":0.05404,"stage2_stop_reason":"end_turn"},"total_usd":0.081764,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"RasGEF1B functions as a highly specific guanine nucleotide exchange factor (GEF) for Rap2, a member of the Rap subfamily of Ras-like G-proteins, but does not act on Rap1 or other Ras subfamily members. Reciprocal site-directed mutagenesis identified Phe39 in the switch I region of Rap2 as the specificity determinant; mutating the corresponding Ser39 in Rap1 to Phe (Rap1-S39F) allowed RasGEF1B to stimulate nucleotide exchange on Rap1.\",\n      \"method\": \"In vitro nucleotide exchange assays with purified RasGEF1B and Ras-family proteins; reciprocal site-directed mutagenesis of Rap1/Rap2 switch I residues\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified proteins plus mutagenesis identifying specificity residue, multiple orthogonal approaches in one study\",\n      \"pmids\": [\"19645719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"RasGEF1B localizes to early endosomes when ectopically expressed in HEK293T cells (found predominantly in the heavy membrane fraction by fractionation and confirmed at early endosomes by confocal microscopy). RasGEF1B was found in close association with Ras in live cells and triggered Ras GTPase activity, indicating it can activate Ras-like proteins at early endosomes. In macrophages, TLR3 (poly I:C) and TLR4 (LPS) induce RasGEF1B expression through the MyD88-independent (TRIF) pathway.\",\n      \"method\": \"Subcellular fractionation, confocal microscopy co-localization, live-cell Ras activity assay; in vivo infection models with MyD88/TRIF knockout macrophages\",\n      \"journal\": \"Genes and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct localization by fractionation and confocal microscopy with functional Ras activation assay, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"20090772\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TLR-induced transcription of Rasgef1b in macrophages is driven by NF-κB acting through a proximal promoter region (-183 to +119) that contains a cluster of five NF-κB binding sites. Site-directed mutagenesis of these κB sites reduced maximal LPS-induced promoter activation. ChIP-seq showed RelA (p65) is recruited to this promoter region upon LPS stimulation. Rela-deficient macrophages or pharmacological NF-κB inhibition (Bay11-7082) reduced optimal Rasgef1b expression, and luciferase reporter assays showed RelA and cRel (but not RelB) activate the promoter.\",\n      \"method\": \"Luciferase reporter assay, site-directed mutagenesis of κB sites, ATAC-seq, ChIP-seq, Rela-deficient macrophages, pharmacological inhibition\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (reporter assay, mutagenesis, ChIP-seq, KO cells) in a single rigorous study establishing the transcriptional regulatory mechanism\",\n      \"pmids\": [\"32866686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Deletion of Rasgef1b in mice alters basal and LPS-induced expression of genes involved in chemotaxis, cytokine responses, and GTPase activity regulation in macrophages. RasGEF1b knockdown in RAW264.7 macrophages impaired transcriptional activation of the Serpinb2 promoter both under constitutive and LPS-stimulated conditions, as demonstrated by luciferase reporter assay.\",\n      \"method\": \"RNA-seq transcriptomics in wild-type vs. Rasgef1b-knockout bone marrow-derived macrophages; RT-qPCR validation; luciferase-based Serpinb2 promoter assay with RasGEF1b knockdown\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNA-seq plus targeted promoter assay with knockdown, single lab, two orthogonal approaches\",\n      \"pmids\": [\"37950057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RasGEF1b deficiency in mice leads to behavioral abnormalities (hyperlocomotion, anhedonia, compulsive-like behavior reversible by fluoxetine), downregulation of dopamine receptor (Drd1, Drd2, Drd4, Drd5) and serotonin receptor (5Htr1a, 5Htr1b, 5Htr1d) mRNAs in hippocampus and prefrontal cortex, morphological alterations in microglia, and decreased hippocampal BDNF levels.\",\n      \"method\": \"Conditional knockout mouse model; behavioral tests; RT-qPCR for receptor mRNAs; microglia morphological analysis; BDNF protein quantification\",\n      \"journal\": \"Progress in neuro-psychopharmacology & biological psychiatry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined genetic KO with multiple phenotypic readouts, single lab, orthogonal methods but no direct mechanistic link to GEF activity\",\n      \"pmids\": [\"38048936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"RASGEF1B suppresses hepatocellular carcinoma through a metabolic–epigenetic axis: RASGEF1B competitively protects ALDH7A1 protein from BMI1-dependent ubiquitination (confirmed by co-immunoprecipitation, GST pull-down, and in vitro reconstituted ubiquitination assay), thereby elevating cellular betaine levels. Elevated betaine promotes SNAI1 DNA methylation via methionine metabolic reprogramming, reducing SNAI1 expression and suppressing epithelial-mesenchymal transition and HCC progression.\",\n      \"method\": \"Co-immunoprecipitation, GST pull-down, immunofluorescence, in vitro reconstituted ubiquitination system, cycloheximide chase, methylation-specific PCR, luciferase reporter assay, transcriptome sequencing, untargeted metabolomics, in vitro and in vivo tumor models\",\n      \"journal\": \"Journal of translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal biochemical methods (GST pull-down, in vitro ubiquitination reconstitution, Co-IP) combined with metabolomics and epigenetic assays in a single rigorous study\",\n      \"pmids\": [\"41742192\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RASGEF1B is a highly specific guanine nucleotide exchange factor for Rap2 (not Rap1 or other Ras GTPases), localizes to early endosomes upon TLR activation, and is transcriptionally induced in macrophages via NF-κB (RelA/cRel) binding to a proximal promoter; beyond canonical GEF activity, RASGEF1B also suppresses hepatocellular carcinoma by protecting ALDH7A1 from BMI1-mediated ubiquitination, thereby elevating betaine and promoting SNAI1 DNA methylation to inhibit epithelial-mesenchymal transition, and its loss in mice disrupts macrophage gene regulation and causes neurochemical and behavioral abnormalities.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RASGEF1B is a guanine nucleotide exchange factor that links innate immune signaling to small-GTPase activation and, independently, restrains tumor progression through a metabolic-epigenetic axis [#0, #5]. As a GEF it is highly specific for the Rap-subfamily GTPase Rap2 and does not act on Rap1 or other Ras-family members, with Phe39 in the Rap2 switch I region serving as the specificity determinant [#0]. The protein localizes to early endosomes, where it associates with and activates Ras-like proteins, and its expression is induced in macrophages downstream of TLR3 and TLR4 via the TRIF (MyD88-independent) pathway [#1]. This induction is driven transcriptionally by NF-\\u03baB: RelA and cRel are recruited to a proximal promoter cluster of \\u03baB sites to activate Rasgef1b in response to LPS [#2]. Loss of Rasgef1b in mice reshapes macrophage transcriptional programs governing chemotaxis, cytokine responses, and GTPase regulation, and produces neurochemical and behavioral abnormalities including altered dopamine/serotonin receptor expression and reduced hippocampal BDNF [#3, #4]. In hepatocellular carcinoma, RASGEF1B competitively protects ALDH7A1 from BMI1-mediated ubiquitination, raising betaine levels that promote SNAI1 DNA methylation and thereby suppress epithelial-mesenchymal transition [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established the core enzymatic identity of RASGEF1B by defining its substrate specificity, answering whether it is a general Ras GEF or a selective one.\",\n      \"evidence\": \"In vitro nucleotide exchange assays with purified proteins plus reciprocal switch I mutagenesis of Rap1/Rap2\",\n      \"pmids\": [\n        \"19645719\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Physiological context in which Rap2 activation by RASGEF1B occurs not addressed\",\n        \"Regulation of GEF activity (autoinhibition, recruitment) not characterized\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected the GEF to a subcellular site and an immune signaling input, showing where it acts and how its expression is triggered.\",\n      \"evidence\": \"Subcellular fractionation and confocal co-localization in HEK293T, live-cell Ras activity assay, and MyD88/TRIF knockout macrophage infection models\",\n      \"pmids\": [\n        \"20090772\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Localization shown for ectopically expressed protein, not endogenous\",\n        \"Ras activation observed but reconciliation with Rap2-specific in vitro activity unresolved\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined the transcriptional mechanism of TLR-induced expression, identifying the specific factors and promoter elements driving induction.\",\n      \"evidence\": \"Luciferase reporters, \\u03baB-site mutagenesis, ATAC-seq, ChIP-seq, Rela-deficient macrophages, and pharmacological NF-\\u03baB inhibition\",\n      \"pmids\": [\n        \"32866686\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Downstream consequences of induced RASGEF1B on macrophage GTPase signaling not traced\",\n        \"Relative contributions of RelA versus cRel in vivo not resolved\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Tested the organism-level requirement for RASGEF1B, revealing its impact on macrophage gene regulation and a specific promoter target.\",\n      \"evidence\": \"RNA-seq of wild-type vs. knockout BMDMs with RT-qPCR validation and Serpinb2 promoter luciferase assay under knockdown\",\n      \"pmids\": [\n        \"37950057\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism linking GEF activity to Serpinb2 promoter regulation not defined\",\n        \"Direct versus indirect transcriptional effects not separated\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended the phenotypic role of RASGEF1B beyond immunity to the nervous system, documenting behavioral and neurochemical consequences of its loss.\",\n      \"evidence\": \"Conditional knockout mouse with behavioral testing, RT-qPCR of neurotransmitter receptors, microglial morphometry, and BDNF quantification\",\n      \"pmids\": [\n        \"38048936\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No direct mechanistic link from GEF/Rap2 activity to neurochemical phenotypes\",\n        \"Cell-type origin of behavioral defects (neuronal vs. microglial) not resolved\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Uncovered a non-canonical tumor-suppressive function, showing RASGEF1B operates through protein stabilization and metabolic reprogramming rather than its GEF activity.\",\n      \"evidence\": \"Co-IP, GST pull-down, in vitro reconstituted ubiquitination, cycloheximide chase, methylation-specific PCR, metabolomics, and in vitro/in vivo HCC models\",\n      \"pmids\": [\n        \"41742192\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether GEF/Rap2 activity contributes to ALDH7A1 protection not determined\",\n        \"Structural basis of competition with BMI1 for ALDH7A1 not defined\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RASGEF1B's Rap2-specific GEF activity, endosomal localization, and tumor-suppressive ALDH7A1-stabilizing function mechanistically integrate within a single protein remains unresolved.\",\n      \"evidence\": \"No single study links the enzymatic, immune, and metabolic-epigenetic roles\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No unifying mechanism connecting GEF activity to ALDH7A1 stabilization\",\n        \"Endogenous interactome and structure not characterized\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\n        \"term_id\": \"GO:0098772\",\n        \"supporting_discovery_ids\": [\n          0\n        ]\n      }\n    ],\n    \"localization\": [\n      {\n        \"term_id\": \"GO:0005768\",\n        \"supporting_discovery_ids\": [\n          1\n        ]\n      }\n    ],\n    \"pathway\": [\n      {\n        \"term_id\": \"R-HSA-168256\",\n        \"supporting_discovery_ids\": [\n          1,\n          2,\n          3\n        ]\n      },\n      {\n        \"term_id\": \"R-HSA-162582\",\n        \"supporting_discovery_ids\": [\n          0,\n          1\n        ]\n      }\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"RAP2\",\n      \"ALDH7A1\",\n      \"BMI1\",\n      \"RELA\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}