{"gene":"EIF2B5","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2000,"finding":"The C-terminal region of eIF2Bε (residues 518–712 in yeast) is required for both catalytic GEF activity and interaction with eIF2, while the N-terminal half is an activation domain that mediates enhancement of nucleotide exchange rate upon eIF2B complex formation. Missense mutations in the N-terminal region impair complex formation-stimulated activity without affecting basal GEF activity of eIF2Bε alone.","method":"In vitro GEF assays, in-frame deletion and missense mutation analysis of yeast eIF2Bε (GCD6), binding assays with eIF2B subunits and eIF2","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with mutagenesis and multiple orthogonal assays (GEF activity, complex formation, eIF2 binding) in a single rigorous study","pmids":["10805739"],"is_preprint":false},{"year":2001,"finding":"DYRK1A and DYRK2 phosphorylate eIF2Bε at Ser539 (rat; equivalent Ser535 context), and this phosphorylation primes the subsequent inhibitory phosphorylation of Ser535 by GSK3 in vitro. eIF2Bε is highly phosphorylated at Ser539 in vivo, establishing a two-kinase sequential phosphorylation cascade that inhibits eIF2Bε GEF activity.","method":"In vitro kinase assays with recombinant DYRK isoforms and GSK3; phospho-specific immunoblotting; in vivo phosphorylation confirmed by metabolic labeling","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of sequential phosphorylation by two kinases with mutagenesis controls and in vivo confirmation, single study with multiple orthogonal methods","pmids":["11311121"],"is_preprint":false},{"year":2002,"finding":"During sepsis, eIF2B kinase activity is elevated and eIF2Bε Ser535 phosphorylation is increased ~2–2.5-fold, correlating with reduced eIF2B GEF activity and impaired skeletal muscle protein synthesis. GSK3 phosphorylation (Ser9, inactivating) is decreased, consistent with activated GSK3 driving eIF2Bε phosphorylation. TNF-binding protein treatment prevents these changes, implicating TNF in the pathway.","method":"Phospho-specific immunoblotting in rat gastrocnemius; eIF2B kinase/phosphatase activity assays; pharmacological inhibition with TNF-binding protein","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo loss-of-function via pharmacological intervention with multiple biochemical readouts, single lab","pmids":["12376332"],"is_preprint":false},{"year":2005,"finding":"EIF2B5 is required for the generation of GFAP+ astrocytes from glial progenitors. RNAi knockdown of EIF2B5 in normal human glial progenitors severely compromised induction of GFAP+ cells, and cultures from a VWM patient with EIF2B5 mutations produced few morphologically normal astrocytes despite normal oligodendrocyte generation.","method":"RNAi knockdown of EIF2B5 in primary human glial progenitors; immunocytochemistry for GFAP; primary cell cultures from VWM patient brain","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — RNAi loss-of-function with specific cellular phenotype replicated in patient-derived cells and normal progenitors with multiple orthogonal approaches","pmids":["15723074"],"is_preprint":false},{"year":2008,"finding":"A splice-site mutation in EIF2B5 causing exon 6 deletion abolishes detectable protein from that allele and severely reduces eIF2B GEF activity, demonstrating that the non-catalytic domain encoded by exon 6 is required for eIF2B complex formation and activity.","method":"RT-PCR of patient lymphoblastoid cells; eIF2B GEF activity assay; protein detection by immunoblot","journal":"Annals of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical GEF assay on patient-derived cells combined with transcript analysis, single lab","pmids":["18294360"],"is_preprint":false},{"year":2008,"finding":"Resistance exercise reduces phosphorylation of eIF2Bε at Ser540 in human skeletal muscle, suggesting exercise-induced activation of eIF2B GEF activity contributes to stimulation of muscle protein synthesis.","method":"Muscle biopsy; phospho-specific immunoblotting in young men under fasted/fed and exercise/rest conditions","journal":"American journal of physiology. Regulatory, integrative and comparative physiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct in vivo measurement in human subjects with controlled conditions, but single lab and no mechanistic follow-up beyond phosphorylation measurement","pmids":["18565837"],"is_preprint":false},{"year":2010,"finding":"Ectopic expression of eIF2Bε in rat tibialis anterior increased eIF2B GEF activity, and expression of eIF2Bε in septic rats rescued the deficit in eIF2B GEF activity and skeletal muscle protein synthesis, demonstrating that eIF2Bε expression level is rate-limiting for GEF activity and protein synthesis in skeletal muscle.","method":"Plasmid transfection into rat tibialis anterior in vivo; GEF activity assay; [3H]phenylalanine incorporation to measure protein synthesis","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vivo gain-of-function with biochemical reconstitution of GEF activity and direct protein synthesis measurement, single lab with two orthogonal functional readouts","pmids":["20484009"],"is_preprint":false},{"year":2013,"finding":"DYRK2 acts as a priming kinase for GSK3β-mediated inhibitory phosphorylation of eIF2Bε in cardiomyocytes. siRNA knockdown of DYRK2 decreased p(S535)-eIF2Bε levels, while adenoviral overexpression of DYRK2 increased eIF2Bε phosphorylation. Constitutively active eIF2Bε-S535A (non-phosphorylatable) promoted cardiac hypertrophy, whereas DYRK2 overexpression reduced cardiomyocyte size and diminished hypertrophic response.","method":"siRNA knockdown; adenoviral overexpression in cultured cardiomyocytes; transgenic mice with cardiac-specific eIF2Bε or eIF2Bε-S535A; immunoblotting; cardiomyocyte size measurement; isoproterenol treatment and aortic banding","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal gain- and loss-of-function experiments in cells and transgenic mice with multiple orthogonal readouts, consistent with mechanistic model from PMID:11311121","pmids":["24023715"],"is_preprint":false},{"year":2013,"finding":"The C-terminal catalytic domain of human eIF2Bε expressed in yeast has GEF activity, and CACH/VWM disease mutations within this domain reduce its GEF activity, as measured in a reconstituted assay with purified human eIF2 and human eIF2Bε C-terminal domain.","method":"Recombinant protein purification from yeast; in vitro GEF assay; comparison of wild-type and disease-mutant forms","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified human proteins and mutagenesis analysis, single lab with rigorous biochemical readout","pmids":["23335982"],"is_preprint":false},{"year":2016,"finding":"eIF2Bε is a downstream effector of the AKT-GSK3β signaling axis in CNS axon regeneration. Constitutive activation of eIF2Bε is sufficient to promote axon regeneration after optic nerve injury, and inactivation of eIF2Bε reduces both GSK3β- and AKT-mediated axon regeneration. This pathway acts independently of mTORC1.","method":"Conditional knockout and constitutively active knock-in alleles of eIF2Bε in mouse retinal ganglion cells; optic nerve crush injury model; axon counting; epistasis by genetic double mutants","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple alleles (loss-of-function and gain-of-function) in an in vivo model with quantitative axon regeneration readouts","pmids":["26974342"],"is_preprint":false},{"year":2017,"finding":"Under hypoxia, intron retention in EIF2B5 creates a premature termination codon producing a 65 kDa truncated eIF2Bε isoform that opposes full-length eIF2Bε and inhibits global translation. Hypoxia-induced SRSF3 binding and increased phospho-Ser2 RNA Pol II at the retained intron promote its retention. Expression of the 65 kDa isoform increases cell survival under hypoxia.","method":"RNA-seq; RT-PCR; western blot to detect truncated protein; overexpression of truncated isoform; polysome profiling/translation assays; RIP for SRSF3; ChIP for RNA Pol II modifications","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (RNA-seq, protein detection, functional translation assay, RIP, ChIP) in a single study establishing mechanism of isoform-based translational regulation","pmids":["28961236"],"is_preprint":false},{"year":2019,"finding":"The Eif2b5 p.Ile98Met mutation in mice decreases eIF2B guanine nucleotide exchange activity on eIF2, elevates ATF4 (integrated stress response marker), and causes neurological defects including epilepsy and shortened lifespan, establishing loss of GEF activity as the proximate biochemical defect in VWM.","method":"GEF activity assay on brain extracts; ATF4 immunoblotting; behavioral and histological analysis of spontaneous mutant mouse","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical GEF assay combined with in vivo phenotypic characterization, single lab","pmids":["31587290"],"is_preprint":false},{"year":2020,"finding":"Intron 12 retention in zebrafish eif2b5 leads to expression of a truncated eif2b5 transcript; forced expression of this truncated form in wild-type zebrafish impairs motor behavior and activates the integrated stress response (ISR), implicating a feed-forward ISR activation as part of VWM pathophysiology.","method":"Zebrafish eif2b5 mutant characterization; mRNA injection of truncated eif2b5 into wild-type larvae; ISR reporter assays; motor behavior assays","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function in vivo with ISR reporter and behavioral readouts, single lab","pmids":["33300869"],"is_preprint":false},{"year":2021,"finding":"eIF2Bε is required for Wnt-mediated clonogenicity and the associated increase in global translational capacity in intestinal epithelial cells. Using eIF2BεArg191His dysfunctional mice, eIF2Bε loss impairs crypt formation, stemness marker expression, and Paneth cell granule formation; Wnt hyperactivation by GSK3β inhibition requires eIF2Bε for clonogenic expansion.","method":"Eif2b5 Arg191His knock-in mice; intestinal organoid culture; GSK3β inhibitor treatment; immunofluorescence; polysome/translation capacity assays","journal":"Stem cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knock-in mouse model with organoid functional assays and translational readouts, single lab","pmids":["34399164"],"is_preprint":false},{"year":2025,"finding":"Cell-type-specific conditional Eif2b5 mutation in oligodendrocytes (but not neurons) recapitulates the major motor phenotype of VWM mice, with unmyelinated axons, immature cycling oligodendrocytes, and reactive astrocytes. Astrocyte-specific Eif2b5 mutation causes vacuolization and elevated ATF4 transcriptome but only mild ataxia. This establishes oligodendrocytes as the primary cell type driving ataxia in VWM, while astrocytes drive ISR/ATF4 pathology.","method":"Cell type-specific Cre-driven conditional Eif2b5 knock-in mice (astrocyte-, oligodendrocyte-, neuron-specific); motor behavior testing; immunohistochemistry; myelin/axon analysis; ATF4 transcriptome analysis","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis via cell-type-specific conditional alleles with multiple orthogonal cellular and molecular readouts across three cell-type lines","pmids":["40326783"],"is_preprint":false},{"year":2025,"finding":"EIF2B5 directly interacts with ribosomal protein RPL6 (identified by mass spectrometry and confirmed by co-immunoprecipitation), and EIF2B5 overexpression promotes RPL6 expression and activates the PI3K/AKT/mTOR pathway, driving HCC cell proliferation and invasion.","method":"Mass spectrometry; co-immunoprecipitation; western blot; siRNA knockdown; overexpression; mouse ectopic tumor assay","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — interaction identified by MS and confirmed by single Co-IP, with in vivo tumor model, single lab","pmids":["40246131"],"is_preprint":false}],"current_model":"EIF2B5 (eIF2Bε) is the catalytic subunit of the heteropentameric eIF2B guanine nucleotide exchange factor: its C-terminal domain directly catalyzes GDP→GTP exchange on eIF2, while its N-terminal domain acts as an activation module responding to complex assembly with the other four eIF2B subunits; its GEF activity is inhibited by sequential phosphorylation at Ser539 by DYRK1A/DYRK2 (priming) followed by GSK3β at Ser535, a cascade activated in sepsis and cardiomyocyte stress to suppress global protein synthesis; under hypoxia, alternative splicing retains an intron creating a truncated dominant-negative isoform that inhibits translation; in the CNS, eIF2Bε functions downstream of the AKT-GSK3β axis to promote axon regeneration independently of mTORC1, and cell-type-specific studies establish that oligodendrocyte-autonomous eIF2Bε dysfunction drives ataxia and hypomyelination while astrocyte-specific dysfunction drives the integrated stress response/ATF4 pathology characteristic of Vanishing White Matter disease."},"narrative":{"mechanistic_narrative":"EIF2B5 (eIF2Bε) is the catalytic subunit of the eIF2B guanine nucleotide exchange factor that controls the rate of global protein synthesis by recycling eIF2-GDP to eIF2-GTP [PMID:10805739, PMID:20484009]. Its C-terminal domain directly catalyzes GDP→GTP exchange on eIF2 and binds eIF2, while its N-terminal half is an activation domain that enhances exchange rate upon assembly with the other eIF2B subunits; disease and deletion mutations in either domain reduce GEF activity [PMID:10805739, PMID:18294360, PMID:23335982]. eIF2Bε expression level is rate-limiting for GEF activity and protein synthesis in skeletal muscle [PMID:20484009]. GEF activity is inhibited by a sequential phosphorylation cascade in which DYRK1A/DYRK2 prime at Ser539 to permit GSK3β-mediated inhibitory phosphorylation at Ser535 [PMID:11311121, PMID:24023715]; this cascade is engaged during sepsis to suppress muscle protein synthesis and in cardiomyocytes to restrain hypertrophy, and is relieved by resistance exercise [PMID:12376332, PMID:24023715, PMID:18565837]. eIF2Bε also acts downstream of the AKT–GSK3β axis to promote CNS axon regeneration independently of mTORC1 [PMID:26974342], and under hypoxia an intron-retention isoform produces a truncated dominant-negative eIF2Bε that opposes the full-length protein and inhibits translation while promoting cell survival [PMID:28961236]. Loss of eIF2Bε GEF activity is the proximate biochemical defect in Vanishing White Matter disease/CACH, elevating ATF4 and the integrated stress response [PMID:23335982, PMID:31587290]; cell-type-specific mouse studies establish that oligodendrocyte-autonomous dysfunction drives ataxia and hypomyelination whereas astrocyte-specific dysfunction drives the ISR/ATF4 pathology [PMID:40326783], and eIF2Bε is required for astrocyte generation from glial progenitors [PMID:15723074].","teleology":[{"year":2000,"claim":"Established the domain architecture of eIF2Bε, separating a C-terminal catalytic/eIF2-binding module from an N-terminal activation domain that responds to complex assembly.","evidence":"In vitro GEF assays with deletion and missense mutants of yeast eIF2Bε plus subunit/eIF2 binding assays","pmids":["10805739"],"confidence":"High","gaps":["Mapped in yeast; precise structural basis of activation by complex formation not resolved","Does not address regulation in vertebrates"]},{"year":2001,"claim":"Defined the inhibitory phosphorylation mechanism by showing DYRK1A/DYRK2 prime Ser539 to enable GSK3-mediated phosphorylation at the inhibitory site.","evidence":"In vitro kinase assays with recombinant DYRK and GSK3, phospho-specific immunoblotting, in vivo metabolic labeling","pmids":["11311121"],"confidence":"High","gaps":["Upstream signals controlling the kinases not defined here","Structural consequence of phosphorylation on GEF activity unresolved"]},{"year":2002,"claim":"Connected the phosphorylation cascade to a physiological stress, showing sepsis raises eIF2Bε Ser535 phosphorylation and suppresses muscle protein synthesis via TNF/GSK3.","evidence":"Phospho-immunoblotting and eIF2B activity assays in rat muscle with TNF-binding protein intervention","pmids":["12376332"],"confidence":"Medium","gaps":["Correlative phosphorylation/activity link","Single lab, indirect kinase involvement"]},{"year":2005,"claim":"Revealed a cell-type-specific requirement by showing eIF2Bε is needed to generate GFAP+ astrocytes from human glial progenitors.","evidence":"RNAi knockdown in human glial progenitors and VWM patient-derived cultures with GFAP immunocytochemistry","pmids":["15723074"],"confidence":"High","gaps":["Molecular basis of selective astrocyte requirement unknown","Does not address oligodendrocyte contribution to disease"]},{"year":2008,"claim":"Showed that exon-6 loss eliminates the protein and severely reduces GEF activity, confirming the non-catalytic domain is required for complex formation and function.","evidence":"RT-PCR, immunoblot and GEF activity assay in patient lymphoblastoid cells","pmids":["18294360"],"confidence":"Medium","gaps":["Patient-cell readout; structural role of exon-6 region not mapped"]},{"year":2008,"claim":"Demonstrated physiological de-repression by showing resistance exercise lowers eIF2Bε inhibitory phosphorylation in human muscle.","evidence":"Phospho-specific immunoblotting of human muscle biopsies under exercise/feeding conditions","pmids":["18565837"],"confidence":"Medium","gaps":["No direct measurement of GEF activity change","Correlation with protein synthesis only inferred"]},{"year":2010,"claim":"Established that eIF2Bε is rate-limiting in vivo by rescuing the septic deficit in muscle GEF activity and protein synthesis through ectopic expression.","evidence":"In vivo plasmid transfection of rat muscle with GEF activity and [3H]phenylalanine incorporation","pmids":["20484009"],"confidence":"High","gaps":["Tissue-specific; whether other subunits are co-limiting not tested"]},{"year":2013,"claim":"Extended the DYRK2/GSK3β cascade to cardiac biology, showing phosphorylation state of eIF2Bε controls cardiomyocyte hypertrophy.","evidence":"Reciprocal siRNA/adenoviral manipulation in cardiomyocytes and transgenic eIF2Bε / S535A mice with hypertrophy assays","pmids":["24023715"],"confidence":"High","gaps":["Downstream translational targets driving hypertrophy not identified"]},{"year":2013,"claim":"Localized VWM disease mutations to the catalytic domain and showed they directly reduce GEF activity in a reconstituted human assay.","evidence":"Purified human eIF2Bε C-terminal domain and eIF2 in vitro GEF assays comparing WT and disease mutants","pmids":["23335982"],"confidence":"High","gaps":["Tested isolated C-terminal domain, not full pentamer","Per-mutation severity not linked to clinical phenotype"]},{"year":2016,"claim":"Placed eIF2Bε downstream of AKT-GSK3β in CNS axon regeneration, independent of mTORC1.","evidence":"Conditional knockout and constitutively active eIF2Bε alleles in retinal ganglion cells with optic nerve crush and genetic epistasis","pmids":["26974342"],"confidence":"High","gaps":["Translational targets mediating regeneration not defined"]},{"year":2017,"claim":"Uncovered an isoform-based regulatory mechanism whereby hypoxia-driven intron retention generates a dominant-negative truncated eIF2Bε that suppresses translation.","evidence":"RNA-seq, RT-PCR, truncated protein detection, polysome profiling, SRSF3 RIP and RNA Pol II ChIP","pmids":["28961236"],"confidence":"High","gaps":["Mechanism by which truncated form opposes full-length not structurally defined","In vivo relevance beyond cell models not shown"]},{"year":2019,"claim":"Established loss of GEF activity with elevated ATF4 as the proximate biochemical defect underlying VWM neuropathology.","evidence":"GEF assay and ATF4 immunoblotting on brain extracts plus behavioral/histological analysis of Eif2b5 I98M mice","pmids":["31587290"],"confidence":"Medium","gaps":["Single mutant allele","Cell types driving phenotype not separated"]},{"year":2020,"claim":"Linked a truncated eif2b5 transcript to feed-forward integrated stress response activation and motor impairment in VWM.","evidence":"Zebrafish eif2b5 mutant analysis with truncated mRNA injection, ISR reporters and motor assays","pmids":["33300869"],"confidence":"Medium","gaps":["Model organism; relevance of feed-forward ISR to mammalian disease not confirmed"]},{"year":2021,"claim":"Showed eIF2Bε is required for Wnt-driven clonogenicity and translational capacity in intestinal stem cells.","evidence":"Eif2b5 R191H knock-in mice and organoids with GSK3β inhibitor treatment and translation assays","pmids":["34399164"],"confidence":"Medium","gaps":["Direct molecular link between Wnt/GSK3β and eIF2Bε activity not isolated"]},{"year":2025,"claim":"Dissected the cellular origin of VWM pathology, assigning ataxia/hypomyelination to oligodendrocyte-autonomous dysfunction and ISR/ATF4 pathology to astrocytes.","evidence":"Cell-type-specific conditional Eif2b5 knock-in mice (oligodendrocyte/astrocyte/neuron) with motor, myelin and ATF4 transcriptome readouts","pmids":["40326783"],"confidence":"High","gaps":["How GEF deficiency selectively impairs oligodendrocyte maturation unresolved","Crosstalk between cell types not fully defined"]},{"year":2025,"claim":"Identified a non-canonical interaction of eIF2Bε with ribosomal protein RPL6 promoting PI3K/AKT/mTOR signaling and hepatocellular carcinoma growth.","evidence":"Mass spectrometry, single Co-IP, knockdown/overexpression and ectopic tumor mouse model","pmids":["40246131"],"confidence":"Medium","gaps":["Single Co-IP without reciprocal validation","Whether interaction is independent of GEF function unclear"]},{"year":null,"claim":"It remains unknown how the GEF deficiency mechanistically produces oligodendrocyte-selective failure and how the canonical eIF2B GEF role integrates with the newly reported RPL6/PI3K-AKT-mTOR axis.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the human pentamer with mutations","Cell-type selectivity of translational vulnerability unexplained","Relationship between GEF-independent functions and canonical activity undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,6,8,11]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,6]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[11,12,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[9,7,15]}],"complexes":["eIF2B"],"partners":["EIF2S1","DYRK1A","DYRK2","GSK3B","RPL6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q13144","full_name":"Translation initiation factor eIF2B subunit epsilon","aliases":["eIF2B GDP-GTP exchange factor subunit epsilon"],"length_aa":721,"mass_kda":80.4,"function":"Acts as a component of the translation initiation factor 2B (eIF2B) complex, which catalyzes the exchange of GDP for GTP on eukaryotic initiation factor 2 (eIF2) gamma subunit (PubMed:25858979, PubMed:27023709, PubMed:31048492). Its guanine nucleotide exchange factor activity is repressed when bound to eIF2 complex phosphorylated on the alpha subunit, thereby limiting the amount of methionyl-initiator methionine tRNA available to the ribosome and consequently global translation is repressed (PubMed:25858979, PubMed:31048492)","subcellular_location":"Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q13144/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/EIF2B5","classification":"Common Essential","n_dependent_lines":1171,"n_total_lines":1208,"dependency_fraction":0.9693708609271523},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"EIF2S3","stoichiometry":0.2},{"gene":"RPS16","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/EIF2B5","total_profiled":1310},"omim":[{"mim_id":"620315","title":"LEUKOENCEPHALOPATHY WITH VANISHING WHITE MATTER 5; VWM5","url":"https://www.omim.org/entry/620315"},{"mim_id":"620314","title":"LEUKOENCEPHALOPATHY WITH VANISHING WHITE MATTER 4; VWM4","url":"https://www.omim.org/entry/620314"},{"mim_id":"620313","title":"LEUKOENCEPHALOPATHY WITH VANISHING WHITE MATTER 3; VWM3","url":"https://www.omim.org/entry/620313"},{"mim_id":"620312","title":"LEUKOENCEPHALOPATHY WITH VANISHING WHITE MATTER 2; VWM2","url":"https://www.omim.org/entry/620312"},{"mim_id":"606687","title":"EUKARYOTIC TRANSLATION INITIATION FACTOR 2B, SUBUNIT 4; EIF2B4","url":"https://www.omim.org/entry/606687"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Cytosol","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/EIF2B5"},"hgnc":{"alias_symbol":["EIF2Bepsilon","EIF-2B"],"prev_symbol":[]},"alphafold":{"accession":"Q13144","domains":[{"cath_id":"3.90.550.10","chopping":"45-300","consensus_level":"medium","plddt":88.3086,"start":45,"end":300},{"cath_id":"2.160.10.10","chopping":"332-455_487-516","consensus_level":"high","plddt":85.2209,"start":332,"end":516},{"cath_id":"1.25.40.180","chopping":"550-721","consensus_level":"high","plddt":82.5425,"start":550,"end":721}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13144","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13144-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13144-F1-predicted_aligned_error_v6.png","plddt_mean":78.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=EIF2B5","jax_strain_url":"https://www.jax.org/strain/search?query=EIF2B5"},"sequence":{"accession":"Q13144","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13144.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13144/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13144"}},"corpus_meta":[{"pmid":"11311121","id":"PMC_11311121","title":"The kinase DYRK phosphorylates protein-synthesis initiation factor eIF2Bepsilon at Ser539 and the microtubule-associated protein tau at Thr212: potential role for DYRK as a glycogen synthase kinase 3-priming kinase.","date":"2001","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/11311121","citation_count":273,"is_preprint":false},{"pmid":"15723074","id":"PMC_15723074","title":"EIF2B5 mutations compromise GFAP+ astrocyte generation in vanishing white matter leukodystrophy.","date":"2005","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/15723074","citation_count":109,"is_preprint":false},{"pmid":"12325082","id":"PMC_12325082","title":"Cree leukoencephalopathy and CACH/VWM disease are allelic at the EIF2B5 locus.","date":"2002","source":"Annals of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/12325082","citation_count":104,"is_preprint":false},{"pmid":"10805739","id":"PMC_10805739","title":"Identification of domains and residues within the epsilon subunit of eukaryotic translation initiation factor 2B (eIF2Bepsilon) required for guanine nucleotide exchange reveals a novel activation function promoted by eIF2B complex formation.","date":"2000","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10805739","citation_count":84,"is_preprint":false},{"pmid":"26974342","id":"PMC_26974342","title":"GSK3β regulates AKT-induced central nervous system axon regeneration via an eIF2Bε-dependent, mTORC1-independent pathway.","date":"2016","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/26974342","citation_count":75,"is_preprint":false},{"pmid":"18565837","id":"PMC_18565837","title":"Resistance exercise decreases eIF2Bepsilon phosphorylation and potentiates the feeding-induced stimulation of p70S6K1 and rpS6 in young men.","date":"2008","source":"American journal of physiology. 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Missense mutations in the N-terminal region impair complex formation-stimulated activity without affecting basal GEF activity of eIF2Bε alone.\",\n      \"method\": \"In vitro GEF assays, in-frame deletion and missense mutation analysis of yeast eIF2Bε (GCD6), binding assays with eIF2B subunits and eIF2\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with mutagenesis and multiple orthogonal assays (GEF activity, complex formation, eIF2 binding) in a single rigorous study\",\n      \"pmids\": [\"10805739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"DYRK1A and DYRK2 phosphorylate eIF2Bε at Ser539 (rat; equivalent Ser535 context), and this phosphorylation primes the subsequent inhibitory phosphorylation of Ser535 by GSK3 in vitro. eIF2Bε is highly phosphorylated at Ser539 in vivo, establishing a two-kinase sequential phosphorylation cascade that inhibits eIF2Bε GEF activity.\",\n      \"method\": \"In vitro kinase assays with recombinant DYRK isoforms and GSK3; phospho-specific immunoblotting; in vivo phosphorylation confirmed by metabolic labeling\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of sequential phosphorylation by two kinases with mutagenesis controls and in vivo confirmation, single study with multiple orthogonal methods\",\n      \"pmids\": [\"11311121\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"During sepsis, eIF2B kinase activity is elevated and eIF2Bε Ser535 phosphorylation is increased ~2–2.5-fold, correlating with reduced eIF2B GEF activity and impaired skeletal muscle protein synthesis. GSK3 phosphorylation (Ser9, inactivating) is decreased, consistent with activated GSK3 driving eIF2Bε phosphorylation. TNF-binding protein treatment prevents these changes, implicating TNF in the pathway.\",\n      \"method\": \"Phospho-specific immunoblotting in rat gastrocnemius; eIF2B kinase/phosphatase activity assays; pharmacological inhibition with TNF-binding protein\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo loss-of-function via pharmacological intervention with multiple biochemical readouts, single lab\",\n      \"pmids\": [\"12376332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"EIF2B5 is required for the generation of GFAP+ astrocytes from glial progenitors. RNAi knockdown of EIF2B5 in normal human glial progenitors severely compromised induction of GFAP+ cells, and cultures from a VWM patient with EIF2B5 mutations produced few morphologically normal astrocytes despite normal oligodendrocyte generation.\",\n      \"method\": \"RNAi knockdown of EIF2B5 in primary human glial progenitors; immunocytochemistry for GFAP; primary cell cultures from VWM patient brain\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — RNAi loss-of-function with specific cellular phenotype replicated in patient-derived cells and normal progenitors with multiple orthogonal approaches\",\n      \"pmids\": [\"15723074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"A splice-site mutation in EIF2B5 causing exon 6 deletion abolishes detectable protein from that allele and severely reduces eIF2B GEF activity, demonstrating that the non-catalytic domain encoded by exon 6 is required for eIF2B complex formation and activity.\",\n      \"method\": \"RT-PCR of patient lymphoblastoid cells; eIF2B GEF activity assay; protein detection by immunoblot\",\n      \"journal\": \"Annals of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical GEF assay on patient-derived cells combined with transcript analysis, single lab\",\n      \"pmids\": [\"18294360\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Resistance exercise reduces phosphorylation of eIF2Bε at Ser540 in human skeletal muscle, suggesting exercise-induced activation of eIF2B GEF activity contributes to stimulation of muscle protein synthesis.\",\n      \"method\": \"Muscle biopsy; phospho-specific immunoblotting in young men under fasted/fed and exercise/rest conditions\",\n      \"journal\": \"American journal of physiology. Regulatory, integrative and comparative physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct in vivo measurement in human subjects with controlled conditions, but single lab and no mechanistic follow-up beyond phosphorylation measurement\",\n      \"pmids\": [\"18565837\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Ectopic expression of eIF2Bε in rat tibialis anterior increased eIF2B GEF activity, and expression of eIF2Bε in septic rats rescued the deficit in eIF2B GEF activity and skeletal muscle protein synthesis, demonstrating that eIF2Bε expression level is rate-limiting for GEF activity and protein synthesis in skeletal muscle.\",\n      \"method\": \"Plasmid transfection into rat tibialis anterior in vivo; GEF activity assay; [3H]phenylalanine incorporation to measure protein synthesis\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vivo gain-of-function with biochemical reconstitution of GEF activity and direct protein synthesis measurement, single lab with two orthogonal functional readouts\",\n      \"pmids\": [\"20484009\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"DYRK2 acts as a priming kinase for GSK3β-mediated inhibitory phosphorylation of eIF2Bε in cardiomyocytes. siRNA knockdown of DYRK2 decreased p(S535)-eIF2Bε levels, while adenoviral overexpression of DYRK2 increased eIF2Bε phosphorylation. Constitutively active eIF2Bε-S535A (non-phosphorylatable) promoted cardiac hypertrophy, whereas DYRK2 overexpression reduced cardiomyocyte size and diminished hypertrophic response.\",\n      \"method\": \"siRNA knockdown; adenoviral overexpression in cultured cardiomyocytes; transgenic mice with cardiac-specific eIF2Bε or eIF2Bε-S535A; immunoblotting; cardiomyocyte size measurement; isoproterenol treatment and aortic banding\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal gain- and loss-of-function experiments in cells and transgenic mice with multiple orthogonal readouts, consistent with mechanistic model from PMID:11311121\",\n      \"pmids\": [\"24023715\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The C-terminal catalytic domain of human eIF2Bε expressed in yeast has GEF activity, and CACH/VWM disease mutations within this domain reduce its GEF activity, as measured in a reconstituted assay with purified human eIF2 and human eIF2Bε C-terminal domain.\",\n      \"method\": \"Recombinant protein purification from yeast; in vitro GEF assay; comparison of wild-type and disease-mutant forms\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified human proteins and mutagenesis analysis, single lab with rigorous biochemical readout\",\n      \"pmids\": [\"23335982\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"eIF2Bε is a downstream effector of the AKT-GSK3β signaling axis in CNS axon regeneration. Constitutive activation of eIF2Bε is sufficient to promote axon regeneration after optic nerve injury, and inactivation of eIF2Bε reduces both GSK3β- and AKT-mediated axon regeneration. This pathway acts independently of mTORC1.\",\n      \"method\": \"Conditional knockout and constitutively active knock-in alleles of eIF2Bε in mouse retinal ganglion cells; optic nerve crush injury model; axon counting; epistasis by genetic double mutants\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple alleles (loss-of-function and gain-of-function) in an in vivo model with quantitative axon regeneration readouts\",\n      \"pmids\": [\"26974342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Under hypoxia, intron retention in EIF2B5 creates a premature termination codon producing a 65 kDa truncated eIF2Bε isoform that opposes full-length eIF2Bε and inhibits global translation. Hypoxia-induced SRSF3 binding and increased phospho-Ser2 RNA Pol II at the retained intron promote its retention. Expression of the 65 kDa isoform increases cell survival under hypoxia.\",\n      \"method\": \"RNA-seq; RT-PCR; western blot to detect truncated protein; overexpression of truncated isoform; polysome profiling/translation assays; RIP for SRSF3; ChIP for RNA Pol II modifications\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (RNA-seq, protein detection, functional translation assay, RIP, ChIP) in a single study establishing mechanism of isoform-based translational regulation\",\n      \"pmids\": [\"28961236\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The Eif2b5 p.Ile98Met mutation in mice decreases eIF2B guanine nucleotide exchange activity on eIF2, elevates ATF4 (integrated stress response marker), and causes neurological defects including epilepsy and shortened lifespan, establishing loss of GEF activity as the proximate biochemical defect in VWM.\",\n      \"method\": \"GEF activity assay on brain extracts; ATF4 immunoblotting; behavioral and histological analysis of spontaneous mutant mouse\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical GEF assay combined with in vivo phenotypic characterization, single lab\",\n      \"pmids\": [\"31587290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Intron 12 retention in zebrafish eif2b5 leads to expression of a truncated eif2b5 transcript; forced expression of this truncated form in wild-type zebrafish impairs motor behavior and activates the integrated stress response (ISR), implicating a feed-forward ISR activation as part of VWM pathophysiology.\",\n      \"method\": \"Zebrafish eif2b5 mutant characterization; mRNA injection of truncated eif2b5 into wild-type larvae; ISR reporter assays; motor behavior assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function in vivo with ISR reporter and behavioral readouts, single lab\",\n      \"pmids\": [\"33300869\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"eIF2Bε is required for Wnt-mediated clonogenicity and the associated increase in global translational capacity in intestinal epithelial cells. Using eIF2BεArg191His dysfunctional mice, eIF2Bε loss impairs crypt formation, stemness marker expression, and Paneth cell granule formation; Wnt hyperactivation by GSK3β inhibition requires eIF2Bε for clonogenic expansion.\",\n      \"method\": \"Eif2b5 Arg191His knock-in mice; intestinal organoid culture; GSK3β inhibitor treatment; immunofluorescence; polysome/translation capacity assays\",\n      \"journal\": \"Stem cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knock-in mouse model with organoid functional assays and translational readouts, single lab\",\n      \"pmids\": [\"34399164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Cell-type-specific conditional Eif2b5 mutation in oligodendrocytes (but not neurons) recapitulates the major motor phenotype of VWM mice, with unmyelinated axons, immature cycling oligodendrocytes, and reactive astrocytes. Astrocyte-specific Eif2b5 mutation causes vacuolization and elevated ATF4 transcriptome but only mild ataxia. This establishes oligodendrocytes as the primary cell type driving ataxia in VWM, while astrocytes drive ISR/ATF4 pathology.\",\n      \"method\": \"Cell type-specific Cre-driven conditional Eif2b5 knock-in mice (astrocyte-, oligodendrocyte-, neuron-specific); motor behavior testing; immunohistochemistry; myelin/axon analysis; ATF4 transcriptome analysis\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis via cell-type-specific conditional alleles with multiple orthogonal cellular and molecular readouts across three cell-type lines\",\n      \"pmids\": [\"40326783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"EIF2B5 directly interacts with ribosomal protein RPL6 (identified by mass spectrometry and confirmed by co-immunoprecipitation), and EIF2B5 overexpression promotes RPL6 expression and activates the PI3K/AKT/mTOR pathway, driving HCC cell proliferation and invasion.\",\n      \"method\": \"Mass spectrometry; co-immunoprecipitation; western blot; siRNA knockdown; overexpression; mouse ectopic tumor assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — interaction identified by MS and confirmed by single Co-IP, with in vivo tumor model, single lab\",\n      \"pmids\": [\"40246131\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"EIF2B5 (eIF2Bε) is the catalytic subunit of the heteropentameric eIF2B guanine nucleotide exchange factor: its C-terminal domain directly catalyzes GDP→GTP exchange on eIF2, while its N-terminal domain acts as an activation module responding to complex assembly with the other four eIF2B subunits; its GEF activity is inhibited by sequential phosphorylation at Ser539 by DYRK1A/DYRK2 (priming) followed by GSK3β at Ser535, a cascade activated in sepsis and cardiomyocyte stress to suppress global protein synthesis; under hypoxia, alternative splicing retains an intron creating a truncated dominant-negative isoform that inhibits translation; in the CNS, eIF2Bε functions downstream of the AKT-GSK3β axis to promote axon regeneration independently of mTORC1, and cell-type-specific studies establish that oligodendrocyte-autonomous eIF2Bε dysfunction drives ataxia and hypomyelination while astrocyte-specific dysfunction drives the integrated stress response/ATF4 pathology characteristic of Vanishing White Matter disease.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"EIF2B5 (eIF2Bε) is the catalytic subunit of the eIF2B guanine nucleotide exchange factor that controls the rate of global protein synthesis by recycling eIF2-GDP to eIF2-GTP [#0, #6]. Its C-terminal domain directly catalyzes GDP→GTP exchange on eIF2 and binds eIF2, while its N-terminal half is an activation domain that enhances exchange rate upon assembly with the other eIF2B subunits; disease and deletion mutations in either domain reduce GEF activity [#0, #4, #8]. eIF2Bε expression level is rate-limiting for GEF activity and protein synthesis in skeletal muscle [#6]. GEF activity is inhibited by a sequential phosphorylation cascade in which DYRK1A/DYRK2 prime at Ser539 to permit GSK3β-mediated inhibitory phosphorylation at Ser535 [#1, #7]; this cascade is engaged during sepsis to suppress muscle protein synthesis and in cardiomyocytes to restrain hypertrophy, and is relieved by resistance exercise [#2, #7, #5]. eIF2Bε also acts downstream of the AKT–GSK3β axis to promote CNS axon regeneration independently of mTORC1 [#9], and under hypoxia an intron-retention isoform produces a truncated dominant-negative eIF2Bε that opposes the full-length protein and inhibits translation while promoting cell survival [#10]. Loss of eIF2Bε GEF activity is the proximate biochemical defect in Vanishing White Matter disease/CACH, elevating ATF4 and the integrated stress response [#8, #11]; cell-type-specific mouse studies establish that oligodendrocyte-autonomous dysfunction drives ataxia and hypomyelination whereas astrocyte-specific dysfunction drives the ISR/ATF4 pathology [#14], and eIF2Bε is required for astrocyte generation from glial progenitors [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established the domain architecture of eIF2Bε, separating a C-terminal catalytic/eIF2-binding module from an N-terminal activation domain that responds to complex assembly.\",\n      \"evidence\": \"In vitro GEF assays with deletion and missense mutants of yeast eIF2Bε plus subunit/eIF2 binding assays\",\n      \"pmids\": [\"10805739\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mapped in yeast; precise structural basis of activation by complex formation not resolved\", \"Does not address regulation in vertebrates\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Defined the inhibitory phosphorylation mechanism by showing DYRK1A/DYRK2 prime Ser539 to enable GSK3-mediated phosphorylation at the inhibitory site.\",\n      \"evidence\": \"In vitro kinase assays with recombinant DYRK and GSK3, phospho-specific immunoblotting, in vivo metabolic labeling\",\n      \"pmids\": [\"11311121\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream signals controlling the kinases not defined here\", \"Structural consequence of phosphorylation on GEF activity unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Connected the phosphorylation cascade to a physiological stress, showing sepsis raises eIF2Bε Ser535 phosphorylation and suppresses muscle protein synthesis via TNF/GSK3.\",\n      \"evidence\": \"Phospho-immunoblotting and eIF2B activity assays in rat muscle with TNF-binding protein intervention\",\n      \"pmids\": [\"12376332\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Correlative phosphorylation/activity link\", \"Single lab, indirect kinase involvement\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Revealed a cell-type-specific requirement by showing eIF2Bε is needed to generate GFAP+ astrocytes from human glial progenitors.\",\n      \"evidence\": \"RNAi knockdown in human glial progenitors and VWM patient-derived cultures with GFAP immunocytochemistry\",\n      \"pmids\": [\"15723074\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of selective astrocyte requirement unknown\", \"Does not address oligodendrocyte contribution to disease\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed that exon-6 loss eliminates the protein and severely reduces GEF activity, confirming the non-catalytic domain is required for complex formation and function.\",\n      \"evidence\": \"RT-PCR, immunoblot and GEF activity assay in patient lymphoblastoid cells\",\n      \"pmids\": [\"18294360\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Patient-cell readout; structural role of exon-6 region not mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated physiological de-repression by showing resistance exercise lowers eIF2Bε inhibitory phosphorylation in human muscle.\",\n      \"evidence\": \"Phospho-specific immunoblotting of human muscle biopsies under exercise/feeding conditions\",\n      \"pmids\": [\"18565837\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct measurement of GEF activity change\", \"Correlation with protein synthesis only inferred\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established that eIF2Bε is rate-limiting in vivo by rescuing the septic deficit in muscle GEF activity and protein synthesis through ectopic expression.\",\n      \"evidence\": \"In vivo plasmid transfection of rat muscle with GEF activity and [3H]phenylalanine incorporation\",\n      \"pmids\": [\"20484009\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific; whether other subunits are co-limiting not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended the DYRK2/GSK3β cascade to cardiac biology, showing phosphorylation state of eIF2Bε controls cardiomyocyte hypertrophy.\",\n      \"evidence\": \"Reciprocal siRNA/adenoviral manipulation in cardiomyocytes and transgenic eIF2Bε / S535A mice with hypertrophy assays\",\n      \"pmids\": [\"24023715\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream translational targets driving hypertrophy not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Localized VWM disease mutations to the catalytic domain and showed they directly reduce GEF activity in a reconstituted human assay.\",\n      \"evidence\": \"Purified human eIF2Bε C-terminal domain and eIF2 in vitro GEF assays comparing WT and disease mutants\",\n      \"pmids\": [\"23335982\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tested isolated C-terminal domain, not full pentamer\", \"Per-mutation severity not linked to clinical phenotype\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Placed eIF2Bε downstream of AKT-GSK3β in CNS axon regeneration, independent of mTORC1.\",\n      \"evidence\": \"Conditional knockout and constitutively active eIF2Bε alleles in retinal ganglion cells with optic nerve crush and genetic epistasis\",\n      \"pmids\": [\"26974342\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Translational targets mediating regeneration not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Uncovered an isoform-based regulatory mechanism whereby hypoxia-driven intron retention generates a dominant-negative truncated eIF2Bε that suppresses translation.\",\n      \"evidence\": \"RNA-seq, RT-PCR, truncated protein detection, polysome profiling, SRSF3 RIP and RNA Pol II ChIP\",\n      \"pmids\": [\"28961236\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which truncated form opposes full-length not structurally defined\", \"In vivo relevance beyond cell models not shown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established loss of GEF activity with elevated ATF4 as the proximate biochemical defect underlying VWM neuropathology.\",\n      \"evidence\": \"GEF assay and ATF4 immunoblotting on brain extracts plus behavioral/histological analysis of Eif2b5 I98M mice\",\n      \"pmids\": [\"31587290\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single mutant allele\", \"Cell types driving phenotype not separated\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Linked a truncated eif2b5 transcript to feed-forward integrated stress response activation and motor impairment in VWM.\",\n      \"evidence\": \"Zebrafish eif2b5 mutant analysis with truncated mRNA injection, ISR reporters and motor assays\",\n      \"pmids\": [\"33300869\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Model organism; relevance of feed-forward ISR to mammalian disease not confirmed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed eIF2Bε is required for Wnt-driven clonogenicity and translational capacity in intestinal stem cells.\",\n      \"evidence\": \"Eif2b5 R191H knock-in mice and organoids with GSK3β inhibitor treatment and translation assays\",\n      \"pmids\": [\"34399164\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between Wnt/GSK3β and eIF2Bε activity not isolated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Dissected the cellular origin of VWM pathology, assigning ataxia/hypomyelination to oligodendrocyte-autonomous dysfunction and ISR/ATF4 pathology to astrocytes.\",\n      \"evidence\": \"Cell-type-specific conditional Eif2b5 knock-in mice (oligodendrocyte/astrocyte/neuron) with motor, myelin and ATF4 transcriptome readouts\",\n      \"pmids\": [\"40326783\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How GEF deficiency selectively impairs oligodendrocyte maturation unresolved\", \"Crosstalk between cell types not fully defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified a non-canonical interaction of eIF2Bε with ribosomal protein RPL6 promoting PI3K/AKT/mTOR signaling and hepatocellular carcinoma growth.\",\n      \"evidence\": \"Mass spectrometry, single Co-IP, knockdown/overexpression and ectopic tumor mouse model\",\n      \"pmids\": [\"40246131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation\", \"Whether interaction is independent of GEF function unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how the GEF deficiency mechanistically produces oligodendrocyte-selective failure and how the canonical eIF2B GEF role integrates with the newly reported RPL6/PI3K-AKT-mTOR axis.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the human pentamer with mutations\", \"Cell-type selectivity of translational vulnerability unexplained\", \"Relationship between GEF-independent functions and canonical activity undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 6, 8, 11]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-72766\", \"supporting_discovery_ids\": [0, 6, 8]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [11, 12, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [9, 7, 15]}\n    ],\n    \"complexes\": [\"eIF2B\"],\n    \"partners\": [\"EIF2S1\", \"DYRK1A\", \"DYRK2\", \"GSK3B\", \"RPL6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}