{"gene":"RANGRF","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2000,"finding":"Mammalian Mog1 binds specifically to RanGTP and stimulates guanine nucleotide release from Ran in vitro, functioning as a guanine nucleotide release factor; after GTP release, Mog1 remains bound to nucleotide-free Ran in a conformation that prevents rebinding of guanine nucleotide, distinguishing it mechanistically from the canonical RanGEF.","method":"In vitro biochemical assay (GTP release assay), binding assay with RanGTP","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with direct biochemical assays, replicated and extended by subsequent studies","pmids":["10811801"],"is_preprint":false},{"year":2001,"finding":"Mog1 residues Asp25, Asp34, and Glu37 within a conserved solvent-exposed loop are critical for GTP release and Ran binding; mutation of Arg30 renders Mog1 hyperactive for GTP release. This loop is functionally analogous to the beta-wedge of RanGEF. Mog1 undergoes nuclear import via physical interactions with the nuclear pore complex (inhibited by wheat germ agglutinin) independently of exogenously added factors, and shuttles between nucleus and cytoplasm.","method":"Site-directed mutagenesis of acidic/basic residues, in vitro GTP release assay, nuclear import assay in permeabilized cells, wheat germ agglutinin inhibition","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis combined with in vitro functional assays and cellular import assays in one study","pmids":["11733047"],"is_preprint":false},{"year":2001,"finding":"The Mog1-Ran interaction interface involves conserved Mog1 residues Asp62 and Glu65, and Ran residue Lys136; mutations at these residues decrease Mog1's ability to bind and release nucleotide from Ran, and cause temperature sensitivity and mislocalization of a nuclear import reporter protein in yeast, demonstrating that Mog1-Ran interaction is necessary for efficient nuclear protein import in vivo. MOG1 shows synthetic lethality with PRP20 (RanGEF).","method":"Site-directed mutagenesis, in vitro binding and GTP release assay, yeast genetics (synthetic lethality, nuclear import reporter mislocalization)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis with both in vitro and in vivo functional validation, synthetic lethality epistasis","pmids":["11509570"],"is_preprint":false},{"year":2001,"finding":"Human MOG1 protein binds to both yeast and human Ran, is concentrated within the nucleus (but also present throughout the cell), and can partially complement growth defects in yeast MOG1-deletion cells, indicating functional conservation of the Ran-binding and nuclear trafficking roles.","method":"Co-immunoprecipitation / binding assay (yeast and human Ran), subcellular localization (immunofluorescence), yeast complementation assay","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding assays and complementation in a single study, single lab","pmids":["11290418"],"is_preprint":false},{"year":2007,"finding":"In yeast, Mog1 deletion dislocates phospholipid N-methyltransferase Opi3p from the nuclear membrane; fission yeast mog1(ts) causes nuclear accumulation of mRNA and is rescued by Cid13 (poly-A polymerase for suc22 mRNA), Crp79 (mRNA export factor), and Ssp1 (stress-response kinase). SpMog1 co-precipitates with Nxt2 and Cid13, implicating Mog1 in mRNA export.","method":"Suppressor screen (multi-copy rescue), fluorescence microscopy (mRNA export assay), co-immunoprecipitation","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic suppressor screen plus co-IP, but single lab, yeast model","pmids":["17651922"],"is_preprint":false},{"year":2008,"finding":"MOG1 interacts with the cytoplasmic Loop II (between transmembrane domains DII and DIII) of Nav1.5, as identified by yeast two-hybrid, GST pull-down, and co-immunoprecipitation in HEK293 cells and native cardiac cells. Co-expression of MOG1 with Nav1.5 increases sodium current density and cell-surface expression of Nav1.5. MOG1 co-localizes with Nav1.5 at the intercalated discs and plasma membrane of cardiomyocytes.","method":"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, patch-clamp electrophysiology, Western blot (surface expression), immunofluorescence/confocal microscopy","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (Y2H, pulldown, Co-IP, electrophysiology, surface expression, localization) in single study, replicated by subsequent independent labs","pmids":["18184654"],"is_preprint":false},{"year":2011,"finding":"The MOG1 missense mutation E83D (Brugada syndrome patient) fails to increase sodium current density when overexpressed and exerts a dominant-negative effect on wild-type MOG1 function; Nav1.5 fails to traffic properly to the cell membrane in the presence of E83D-MOG1. Silencing endogenous MOG1 with siRNA reduced INa density by 54%.","method":"Patch-clamp electrophysiology, siRNA knockdown, microscopy (trafficking), overexpression in HEK-Nav1.5 stable cells","journal":"Circulation. Cardiovascular genetics","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis-based functional assay (patch-clamp + trafficking microscopy + siRNA KD) in well-controlled heterologous expression system","pmids":["21447824"],"is_preprint":false},{"year":2011,"finding":"The nonsense variant p.E61X in MOG1/RANGRF completely eliminates the sodium current-increasing effect of MOG1 when expressed in CHO-K1 cells co-expressing Nav1.5; mimicking heterozygosity by co-expression with wild-type MOG1 did not reduce current, indicating no dominant-negative effect for this variant.","method":"Patch-clamp electrophysiology in CHO-K1 cells, co-expression with Nav1.5","journal":"The Canadian journal of cardiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiological assay, single lab, single method","pmids":["21621375"],"is_preprint":false},{"year":2013,"finding":"MOG1 knockdown (siRNA) causes retention of Nav1.5 in the endoplasmic reticulum, disrupts the distribution of Nav1.5 into caveolin-3-enriched microdomains, and reduces plasma membrane expression and INa density. MOG1 does not affect Nav1.5 plasma membrane turnover. MOG1 overexpression rescues reduced plasma membrane expression and INa for the trafficking-defective Nav1.5 mutations D1275N and G1743R.","method":"siRNA knockdown, cell surface protein quantification, patch-clamp electrophysiology, subcellular fractionation/immunofluorescence (ER retention, caveolin-3 microdomains), overexpression rescue assay","journal":"Circulation. Arrhythmia and electrophysiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (siRNA, surface expression quantification, compartment analysis, electrophysiology, rescue assay) in a single well-controlled study","pmids":["23420830"],"is_preprint":false},{"year":2016,"finding":"Knockdown of mog1 in zebrafish embryos decreases heart rate and causes abnormal cardiac looping during embryogenesis; overexpression of human MOG1 increases heart rate. Mechanistically, mog1 knockdown reduces expression of hcn4 (pacemaker channel), nkx2.5, gata4, and hand2 (cardiac morphogenesis transcription factors).","method":"Zebrafish morpholino knockdown, mog1 mRNA overexpression, heart rate measurement, whole-mount imaging, RT-PCR/gene expression analysis","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with specific phenotypic readout and downstream gene expression analysis, single lab","pmids":["26903377"],"is_preprint":false},{"year":2018,"finding":"The MOG1 domain required for interaction with Nav1.5 maps to amino acids 146–155, with Asp148, Arg150, and Ser151 forming a peptide loop essential for Nav1.5 binding. The BrS-associated substitution E83D and mutations D148Q, R150Q, S151Q disrupt MOG1-Nav1.5 interaction and significantly reduce Nav1.5 trafficking to the cell surface. Structural analysis indicates that Glu83 and the loop containing Asp148/Arg150/Ser151 are spatially proximal, forming a critical Nav1.5 binding site.","method":"Large deletion analysis, alanine-scanning mutagenesis, site-directed mutagenesis, GST pull-down, patch-clamp electrophysiology, cell surface protein quantification, 3D structural analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic deletion + mutagenesis + pull-down + electrophysiology + structural analysis in one study","pmids":["30282806"],"is_preprint":false},{"year":2018,"finding":"In Saccharomyces cerevisiae, Mog1 is required to sustain normal levels of histone H2B monoubiquitination (H2Bub1) and H3K4me3; Mog1 is needed for gene-body recruitment of Rad6, Bre1, and Rtf1 (H2B ubiquitination machinery). Mog1 co-precipitates with Bre1, Rtf1, and COMPASS-associated factors Shg1 and Sdc1. Loss of MOG1 impacts transcription, DNA replication, and mRNA export linked to H2Bub1.","method":"ChIP, co-immunoprecipitation, genetic interaction analysis, mRNA export assay, chromatin immunoprecipitation","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and Co-IP in yeast model, single lab, multiple orthogonal methods","pmids":["30249596"],"is_preprint":false},{"year":2020,"finding":"Mog1 knockout zebrafish develop cardiac hypertrophy and heart failure. Mechanistically, mog1 knockout decreases tbx5 expression, which reduces cryab and hspb2 expression, causing cardiac hypertrophy; overexpression of cryab, hspb2, or tbx5 rescues the cardiac edema phenotype. Mog1 KO also causes QRS and QTc prolongation, reduced heart rate associated with reduced scn1b expression, and abnormal cardiac looping associated with reduced nkx2.5, gata4, and hand2 expression.","method":"TALEN-generated knockout zebrafish, echocardiography, RNA-seq, KEGG pathway analysis, RT-PCR, rescue by overexpression (cryab, hspb2, tbx5), whole-mount in situ hybridization, telemetry ECG","journal":"Acta physiologica (Oxford, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with epistasis (rescue experiments), multiple phenotypic readouts, single lab","pmids":["33032360"],"is_preprint":false},{"year":2021,"finding":"The MOG1-Nav1.5 interaction domain on Nav1.5 maps to Loop I (connecting transmembrane domains I and II), specifically to the five-amino-acid motif F530-T531-F532-R533-R534; mutations F530A, F532A, R533A, and R534A significantly reduce MOG1-Nav1.5 interaction and eliminate MOG1-enhanced INa. On the MOG1 side, residues D24, E36, D44, E53, and E101 are critical for interaction with Nav1.5 Loop I. BrS-associated mutation p.F532C abolishes Nav1.5 interaction with MOG1 and reduces MOG1-enhanced INa.","method":"Large deletion analysis, microdeletion analysis, site-directed mutagenesis, GST pull-down, co-immunoprecipitation, cell surface protein quantification, patch-clamp electrophysiology","journal":"Heart rhythm","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic deletion + point mutagenesis + pull-down + Co-IP + surface expression + electrophysiology in one study","pmids":["34843967"],"is_preprint":false},{"year":2022,"finding":"AAV9-mediated MOG1 gene therapy in a Scn5a knock-in Brugada syndrome mouse model increased cell surface expression of Nav1.5, increased ventricular INa, reversed upregulation of Kcnd3 and Cacna1c, normalized cardiac action potentials, abolished J waves, and blocked ventricular tachyarrhythmias. MOG1 acts as a chaperone that binds Nav1.5 and traffics it to the cell surface.","method":"AAV9 gene delivery in knock-in mouse model, patch-clamp electrophysiology, ECG, Western blot (surface expression), action potential recording","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo gene therapy rescue in KI mouse model with multiple orthogonal phenotypic readouts, replicated across two mouse models","pmids":["35675436"],"is_preprint":false},{"year":2022,"finding":"Mog1-/- (knockout) mice exhibit prolonged QRS duration, LV systolic dysfunction, increased ventricular fibrosis, and isoproterenol-induced arrhythmias and sudden death. Notably, cardiac expression and function of Nav1.5 are normal in Mog1-/- mice at baseline. Mog1 deficiency reduces cardiac Cx43 (Gja1) expression and impairs gap-junction function; treatment with Cx43 gap-junction enhancer ZP123 decreased arrhythmia inducibility. Mog1 KO also dysregulates Mmp2, mitochondrial dynamics, and increases ATP supply.","method":"Mog1 knockout mouse, whole-cell patch-clamp, RNA-seq, iTRAQ proteomics, RT-qPCR, Western blot, immunofluorescence, dye transfer assay (gap junction function), transmission electron microscopy, isoproterenol challenge","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple orthogonal methods (electrophysiology, proteomics, transcriptomics, gap junction assay, EM, pharmacological rescue), single lab","pmids":["35533905"],"is_preprint":false},{"year":2025,"finding":"The MOG1-Nav1.5 interaction domain in Nav1.5 Loop II (residues 940–1200) maps to V1190-H1200; point mutations reveal R1195, Y1199, and H1200 as critical for MOG1-Nav1.5 Loop II interaction. Patient variants p.R1195C and p.Y1199S weaken MOG1-Nav1.5 interaction and reduce MOG1-enhanced INa; p.Y1199S additionally generates late INa. These variants are associated with LQTS and cardiac arrhythmias.","method":"Large deletion analysis, small deletion analysis, site-directed mutagenesis, GST pull-down, patch-clamp electrophysiology (INa and late INa) in tsA201 cells and neonatal rat cardiomyocytes","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic mutagenesis + pull-down + electrophysiology in one study with patient variant functional validation","pmids":["40543898"],"is_preprint":false},{"year":2025,"finding":"MOG1 variant L18F (identified in a LQTS proband) increases late sodium current (INaL) and enhances NaV1.8 expression at the sarcolemma in ventricular cardiomyocytes; this prolongs action potential duration and causes EADs, DADs, and triggered activity. The NaV1.8 inhibitor A-803467 reversed the cellular electrophysiological effects of MOG1L18F and reduced arrhythmia inducibility in vivo. NaV1.8 interacts with both MOG1 and NaV1.5.","method":"AAV9-mediated cardiac-specific mouse model, surface ECG, programmed electrical stimulation, optical mapping, patch-clamp (INaL, action potential), Ca2+ dynamics, Western blot/immunofluorescence (surface NaV1.8), pharmacological inhibition (A-803467)","journal":"medRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — preprint, multiple orthogonal methods (in vivo mouse model, electrophysiology, pharmacological rescue), single lab, not yet peer-reviewed","pmids":["41445668"],"is_preprint":true}],"current_model":"RANGRF/MOG1 is a small, evolutionarily conserved nuclear protein that functions both as a Ran GTPase guanine nucleotide release factor—binding RanGTP via a conserved acidic loop (Asp25/Asp34/Glu37 in yeast; Asp62/Glu65 in the Ran interface) to stimulate GTP release and facilitate nuclear protein import—and as a dedicated chaperone for the cardiac sodium channel Nav1.5, physically interacting with Nav1.5 at Loop I (F530–R534 motif) and Loop II (R1195/Y1199/H1200) to promote Nav1.5 trafficking from the ER through caveolin-3-enriched microdomains to the plasma membrane, thereby increasing INa density; loss-of-function mutations (E83D, E61X) or knockdown reduce Nav1.5 surface expression and INa causing Brugada syndrome, while a gain-of-function variant (L18F) increases late INa via NaV1.8 upregulation causing Long QT syndrome, and in vivo MOG1 additionally regulates cardiac morphogenesis, gap junction (Cx43) function, and a tbx5–cryab–hspb2 signaling axis."},"narrative":{"mechanistic_narrative":"RANGRF (MOG1) is a small, evolutionarily conserved nuclear protein that operates as a Ran GTPase guanine nucleotide release factor and, in cardiac tissue, as a dedicated trafficking chaperone for the voltage-gated sodium channel Nav1.5 [PMID:10811801, PMID:18184654]. In its Ran-related role, MOG1 binds RanGTP and stimulates GTP release, then remains bound to nucleotide-free Ran to block guanine-nucleotide rebinding, a mechanism distinct from the canonical RanGEF [PMID:10811801]; a conserved solvent-exposed acidic loop (Asp25/Asp34/Glu37) and interface residues Asp62/Glu65 mediate this activity, and disruption of the MOG1–Ran interaction impairs nuclear protein import in vivo [PMID:11733047, PMID:11509570]. Independent of its Ran activity, MOG1 binds Nav1.5 through cytoplasmic Loop I (the F530–R534 motif) and Loop II (R1195/Y1199/H1200), using a discrete MOG1 surface that includes Glu83 and a Asp148/Arg150/Ser151 loop, and drives Nav1.5 trafficking out of the endoplasmic reticulum through caveolin-3-enriched microdomains to the plasma membrane, thereby raising sodium current (INa) density [PMID:18184654, PMID:23420830, PMID:30282806, PMID:34843967, PMID:40543898]. Loss-of-function MOG1 variants (E83D, E61X) and knockdown trap Nav1.5 in the ER and reduce surface expression and INa, causing Brugada syndrome, whereas variants weakening the Loop II interaction (R1195C, Y1199S) and the L18F variant prolong repolarization and cause Long QT syndrome [PMID:21447824, PMID:21621375, PMID:34843967, PMID:40543898]; AAV9-delivered MOG1 restores Nav1.5 surface expression and suppresses arrhythmias in a Brugada mouse model [PMID:35675436]. Beyond channel trafficking, MOG1 governs cardiac morphogenesis and contractile homeostasis: it supports Cx43 gap-junction function [PMID:35533905] and a tbx5–cryab–hspb2 axis whose loss produces cardiac hypertrophy and looping defects [PMID:26903377, PMID:33032360]. In yeast, MOG1 additionally contributes to mRNA export and to histone H2B monoubiquitination/H3K4me3 via recruitment of Rad6/Bre1/Rtf1 [PMID:17651922, PMID:30249596].","teleology":[{"year":2000,"claim":"Establishing MOG1's biochemical activity answered whether it acts in the Ran cycle, showing it is a non-canonical guanine nucleotide release factor that locks Ran nucleotide-free.","evidence":"In vitro GTP release and RanGTP binding assays with mammalian Mog1","pmids":["10811801"],"confidence":"High","gaps":["Cellular consequence of Ran-nucleotide release not yet linked to a specific import cargo","Structure of the Mog1-Ran complex not resolved"]},{"year":2001,"claim":"Mutagenesis and in vivo yeast genetics mapped the Ran-binding determinants and established that MOG1-Ran interaction is required for efficient nuclear protein import.","evidence":"Site-directed mutagenesis (Asp25/Asp34/Glu37, Asp62/Glu65), in vitro GTP release, permeabilized-cell import assay, yeast synthetic lethality with PRP20 and import-reporter mislocalization","pmids":["11733047","11509570","11290418"],"confidence":"High","gaps":["Identity of physiological import cargoes incomplete","How MOG1 nucleocytoplasmic shuttling is regulated unknown"]},{"year":2007,"claim":"Yeast genetic and co-IP analyses extended MOG1 function beyond import into nuclear membrane organization and mRNA export.","evidence":"Multi-copy suppressor screen, mRNA export microscopy, co-IP with Nxt2/Cid13 in fission yeast","pmids":["17651922"],"confidence":"Medium","gaps":["Direct mechanism connecting MOG1 to mRNA export machinery unresolved","Conservation of mRNA-export role in mammals not tested"]},{"year":2008,"claim":"Identification of a physical MOG1-Nav1.5 interaction defined an entirely new, cardiac-specific function as a sodium-channel trafficking partner.","evidence":"Yeast two-hybrid, GST pull-down, co-IP in HEK293 and cardiac cells, patch-clamp, surface biotinylation, confocal localization to intercalated discs","pmids":["18184654"],"confidence":"High","gaps":["Whether the Ran and Nav1.5 functions are mechanistically coupled unaddressed","Initial mapping limited to Loop II"]},{"year":2011,"claim":"Functional testing of patient variants showed loss of MOG1 trafficking activity causes Brugada syndrome, with E83D acting dominant-negatively and E61X without dominant-negative effect.","evidence":"Patch-clamp, siRNA knockdown, trafficking microscopy in HEK-Nav1.5 and CHO-K1 co-expression systems","pmids":["21447824","21621375"],"confidence":"High","gaps":["Structural basis of the E83D dominant-negative effect not defined here","Variant penetrance and modifier effects in patients not addressed"]},{"year":2013,"claim":"Defining the trafficking step established that MOG1 promotes Nav1.5 ER exit and entry into caveolin-3 microdomains rather than affecting membrane turnover.","evidence":"siRNA knockdown, surface protein quantification, subcellular fractionation, patch-clamp, rescue of trafficking-defective Nav1.5 mutants","pmids":["23420830"],"confidence":"High","gaps":["Molecular machinery linking MOG1 to ER export not identified","Role of caveolin-3 interaction direct vs indirect unresolved"]},{"year":2016,"claim":"Whole-organism loss-of-function revealed a developmental cardiac role beyond channel trafficking, linking MOG1 to heart rate and morphogenesis gene expression.","evidence":"Zebrafish morpholino knockdown and mRNA overexpression, heart-rate measurement, hcn4/nkx2.5/gata4/hand2 expression analysis","pmids":["26903377"],"confidence":"Medium","gaps":["Whether morphogenesis defects are channel-dependent or independent unclear","Direct vs indirect control of transcription factors not established"]},{"year":2018,"claim":"Systematic mapping localized the Nav1.5-binding surface on MOG1 to a spatially proximal Glu83/Asp148-Arg150-Ser151 site, mechanistically explaining how the BrS E83D variant disrupts trafficking.","evidence":"Deletion and alanine-scanning mutagenesis, GST pull-down, patch-clamp, surface quantification, 3D structural analysis","pmids":["30282806"],"confidence":"High","gaps":["Full atomic structure of the MOG1-Nav1.5 complex still lacking","Relationship of this surface to the Ran-binding loop not resolved"]},{"year":2018,"claim":"Yeast chromatin studies uncovered a conserved role for MOG1 in promoting H2B monoubiquitination and H3K4me3 via recruitment of the Rad6/Bre1/Rtf1 machinery.","evidence":"ChIP, co-IP with Bre1/Rtf1/Shg1/Sdc1, genetic interaction and mRNA export assays in S. cerevisiae","pmids":["30249596"],"confidence":"Medium","gaps":["Whether the chromatin role is conserved in mammals untested","Direct vs Ran-dependent contribution to chromatin marks unclear"]},{"year":2021,"claim":"Mapping the Nav1.5 Loop I motif (F530-R534) and the reciprocal MOG1 acidic residues defined a second, structurally specific binding interface whose disruption (e.g., F532C) causes Brugada syndrome.","evidence":"Deletion and point mutagenesis, GST pull-down, co-IP, surface quantification, patch-clamp","pmids":["34843967"],"confidence":"High","gaps":["How Loop I and Loop II interactions cooperate during trafficking unresolved","Stoichiometry of the MOG1-Nav1.5 complex unknown"]},{"year":2022,"claim":"In vivo gene therapy demonstrated MOG1 restoration is sufficient to correct the Brugada phenotype, confirming its causal trafficking-chaperone role and therapeutic potential.","evidence":"AAV9-MOG1 delivery in Scn5a knock-in mice, patch-clamp, ECG, surface Western blot, action potential recording","pmids":["35675436"],"confidence":"High","gaps":["Durability and off-target effects of gene therapy not addressed","Translation to human BrS untested"]},{"year":2022,"claim":"Constitutive knockout mice revealed Nav1.5-independent cardiac functions, implicating MOG1 in Cx43 gap-junction integrity, fibrosis, and mitochondrial dynamics.","evidence":"Mog1 KO mouse, patch-clamp, RNA-seq, iTRAQ proteomics, gap-junction dye transfer, EM, ZP123 pharmacological rescue, isoproterenol challenge","pmids":["35533905"],"confidence":"High","gaps":["Mechanism linking MOG1 to Cx43 expression unknown","Why baseline Nav1.5 is normal in KO yet siRNA reduces INa unresolved"]},{"year":2025,"claim":"Mapping the Loop II interaction site and characterizing LQTS patient variants showed that weakened MOG1-Nav1.5 binding and late-INa generation underlie Long QT phenotypes.","evidence":"Deletion and point mutagenesis (R1195/Y1199/H1200), GST pull-down, patch-clamp (INa and late INa) in tsA201 cells and neonatal rat cardiomyocytes","pmids":["40543898"],"confidence":"High","gaps":["Mechanism by which Y1199S generates late INa not defined","Genotype-phenotype relationship across variants incomplete"]},{"year":2025,"claim":"Characterization of the gain-of-function L18F variant connected MOG1 to NaV1.8 upregulation as an arrhythmogenic mechanism in Long QT syndrome.","evidence":"AAV9 cardiac mouse model, ECG, programmed stimulation, optical mapping, patch-clamp (INaL), surface NaV1.8 detection, A-803467 inhibition (preprint)","pmids":["41445668"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Mechanism by which MOG1 L18F upregulates NaV1.8 unknown","Direct vs indirect MOG1-NaV1.8 interaction not fully defined"]},{"year":null,"claim":"How MOG1's ancestral Ran/nuclear-import and chromatin functions mechanistically relate to its cardiac channel-chaperone and gap-junction roles remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of the full MOG1-Nav1.5 complex","Whether nuclear and cardiac functions share a common molecular surface unknown","Discrepancy between knockdown and knockout effects on baseline Nav1.5 unexplained"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[5,8,10,13,16]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[5,8,14]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,3]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,3]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5,8]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[8]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,2,8]},{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[14,15,16]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[9,12]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[11]}],"complexes":[],"partners":["RAN","SCN5A","SCN10A","GJA1","BRE1","RTF1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9HD47","full_name":"Ran guanine nucleotide release factor","aliases":["Ran-binding protein MOG1"],"length_aa":186,"mass_kda":20.4,"function":"May regulate the intracellular trafficking of RAN (PubMed:11290418). Promotes guanine nucleotide release from RAN and inhibits binding of new GTP by preventing the binding of the RAN guanine nucleotide exchange factor RCC1 (PubMed:29040603). Regulates the levels of GTP-bound RAN in the nucleus, and thereby plays a role in the regulation of RAN-dependent mitotic spindle dynamics (PubMed:29040603). Enhances the expression of SCN5A at the cell membrane in cardiomyocytes (PubMed:18184654, PubMed:21621375, PubMed:23420830)","subcellular_location":"Nucleus; Cytoplasm, perinuclear region; Cytoplasm; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9HD47/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RANGRF","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000108961","cell_line_id":"CID001619","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":3}],"interactors":[{"gene":"RAN","stoichiometry":0.2},{"gene":"RANBP3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001619","total_profiled":1310},"omim":[{"mim_id":"607954","title":"RAN GUANINE NUCLEOTIDE RELEASE FACTOR; RANGRF","url":"https://www.omim.org/entry/607954"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RANGRF"},"hgnc":{"alias_symbol":["MOG1","HSPC165","HSPC236","RANGNRF"],"prev_symbol":[]},"alphafold":{"accession":"Q9HD47","domains":[{"cath_id":"3.40.1000.10","chopping":"39-146","consensus_level":"medium","plddt":81.3796,"start":39,"end":146}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HD47","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HD47-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HD47-F1-predicted_aligned_error_v6.png","plddt_mean":78.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RANGRF","jax_strain_url":"https://www.jax.org/strain/search?query=RANGRF"},"sequence":{"accession":"Q9HD47","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9HD47.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9HD47/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HD47"}},"corpus_meta":[{"pmid":"21447824","id":"PMC_21447824","title":"MOG1: a new susceptibility gene for Brugada syndrome.","date":"2011","source":"Circulation. Cardiovascular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21447824","citation_count":113,"is_preprint":false},{"pmid":"8462850","id":"PMC_8462850","title":"The mog-1 gene is required for the switch from spermatogenesis to oogenesis in Caenorhabditis elegans.","date":"1993","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8462850","citation_count":87,"is_preprint":false},{"pmid":"18184654","id":"PMC_18184654","title":"Identification of a new co-factor, MOG1, required for the full function of cardiac sodium channel Nav 1.5.","date":"2008","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18184654","citation_count":74,"is_preprint":false},{"pmid":"10022905","id":"PMC_10022905","title":"The Caenorhabditis elegans sex determination gene mog-1 encodes a member of the DEAH-Box protein family.","date":"1999","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10022905","citation_count":62,"is_preprint":false},{"pmid":"23420830","id":"PMC_23420830","title":"MOG1 rescues defective trafficking of Na(v)1.5 mutations in Brugada syndrome and sick sinus syndrome.","date":"2013","source":"Circulation. Arrhythmia and electrophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/23420830","citation_count":54,"is_preprint":false},{"pmid":"21621375","id":"PMC_21621375","title":"A novel nonsense variant in Nav1.5 cofactor MOG1 eliminates its sodium current increasing effect and may increase the risk of arrhythmias.","date":"2011","source":"The Canadian journal of cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/21621375","citation_count":44,"is_preprint":false},{"pmid":"10811801","id":"PMC_10811801","title":"The mammalian Mog1 protein is a guanine nucleotide release factor for Ran.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10811801","citation_count":42,"is_preprint":false},{"pmid":"35675436","id":"PMC_35675436","title":"Gene therapy targeting protein trafficking regulator MOG1 in mouse models of Brugada syndrome, arrhythmias, and mild cardiomyopathy.","date":"2022","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35675436","citation_count":35,"is_preprint":false},{"pmid":"11509570","id":"PMC_11509570","title":"Interaction between Ran and Mog1 is required for efficient nuclear protein import.","date":"2001","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11509570","citation_count":24,"is_preprint":false},{"pmid":"33032360","id":"PMC_33032360","title":"Mog1 knockout causes cardiac hypertrophy and heart failure by downregulating tbx5-cryab-hspb2 signalling in zebrafish.","date":"2020","source":"Acta physiologica (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/33032360","citation_count":20,"is_preprint":false},{"pmid":"11290418","id":"PMC_11290418","title":"Identification and characterization of the human MOG1 gene.","date":"2001","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/11290418","citation_count":20,"is_preprint":false},{"pmid":"26903377","id":"PMC_26903377","title":"Cardiac sodium channel regulator MOG1 regulates cardiac morphogenesis and rhythm.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26903377","citation_count":19,"is_preprint":false},{"pmid":"30249596","id":"PMC_30249596","title":"A role for Mog1 in H2Bub1 and H3K4me3 regulation affecting RNAPII transcription and mRNA export.","date":"2018","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/30249596","citation_count":18,"is_preprint":false},{"pmid":"30282806","id":"PMC_30282806","title":"Mechanistic insights into the interaction of the MOG1 protein with the cardiac sodium channel Nav1.5 clarify the molecular basis of Brugada syndrome.","date":"2018","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30282806","citation_count":18,"is_preprint":false},{"pmid":"24142675","id":"PMC_24142675","title":"Brugada syndrome and p.E61X_RANGRF.","date":"2013","source":"Cardiology journal","url":"https://pubmed.ncbi.nlm.nih.gov/24142675","citation_count":15,"is_preprint":false},{"pmid":"34843967","id":"PMC_34843967","title":"Mechanistic insights into the interaction of cardiac sodium channel Nav1.5 with MOG1 and a new molecular mechanism for Brugada syndrome.","date":"2021","source":"Heart rhythm","url":"https://pubmed.ncbi.nlm.nih.gov/34843967","citation_count":12,"is_preprint":false},{"pmid":"24438356","id":"PMC_24438356","title":"The perfect storm? Histiocytoid cardiomyopathy and compound CACNA2D1 and RANGRF mutation in a baby.","date":"2014","source":"Cardiology in the young","url":"https://pubmed.ncbi.nlm.nih.gov/24438356","citation_count":9,"is_preprint":false},{"pmid":"11733047","id":"PMC_11733047","title":"Identification of a conserved loop in Mog1 that releases GTP from Ran.","date":"2001","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/11733047","citation_count":9,"is_preprint":false},{"pmid":"35533905","id":"PMC_35533905","title":"Mog1 deficiency promotes cardiac contractile dysfunction and isoproterenol-induced arrhythmias associated with cardiac fibrosis and Cx43 remodeling.","date":"2022","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/35533905","citation_count":8,"is_preprint":false},{"pmid":"17651922","id":"PMC_17651922","title":"Identification of novel suppressors for Mog1 implies its involvement in RNA metabolism, lipid metabolism and signal transduction.","date":"2007","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/17651922","citation_count":6,"is_preprint":false},{"pmid":"29141529","id":"PMC_29141529","title":"Experimental Autoimmune Encephalomyelitis (EAE) Model of Cynomolgus Macaques Induced by Recombinant Human MOG1-125 (rhMOG1-125) Protein and MOG34-56 Peptide.","date":"2018","source":"Protein and peptide letters","url":"https://pubmed.ncbi.nlm.nih.gov/29141529","citation_count":4,"is_preprint":false},{"pmid":"40543898","id":"PMC_40543898","title":"Molecular mechanism for the interaction of MOG1 with the intracellular loop II of cardiac sodium channel Nav1.5 and its role in arrhythmias.","date":"2025","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/40543898","citation_count":1,"is_preprint":false},{"pmid":"37327621","id":"PMC_37327621","title":"Generation of a homozygous RANGRF knockout hiPSC line by CRISPR/Cas9 system.","date":"2023","source":"Stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/37327621","citation_count":0,"is_preprint":false},{"pmid":"41445668","id":"PMC_41445668","title":"MOG1L18F-mediated increase in late sodium current produces Long QT Syndrome.","date":"2025","source":"medRxiv : the preprint server for health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41445668","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14699,"output_tokens":5323,"usd":0.061971,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13712,"output_tokens":4927,"usd":0.095867,"stage2_stop_reason":"end_turn"},"total_usd":0.157838,"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\": 2000,\n      \"finding\": \"Mammalian Mog1 binds specifically to RanGTP and stimulates guanine nucleotide release from Ran in vitro, functioning as a guanine nucleotide release factor; after GTP release, Mog1 remains bound to nucleotide-free Ran in a conformation that prevents rebinding of guanine nucleotide, distinguishing it mechanistically from the canonical RanGEF.\",\n      \"method\": \"In vitro biochemical assay (GTP release assay), binding assay with RanGTP\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with direct biochemical assays, replicated and extended by subsequent studies\",\n      \"pmids\": [\"10811801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Mog1 residues Asp25, Asp34, and Glu37 within a conserved solvent-exposed loop are critical for GTP release and Ran binding; mutation of Arg30 renders Mog1 hyperactive for GTP release. This loop is functionally analogous to the beta-wedge of RanGEF. Mog1 undergoes nuclear import via physical interactions with the nuclear pore complex (inhibited by wheat germ agglutinin) independently of exogenously added factors, and shuttles between nucleus and cytoplasm.\",\n      \"method\": \"Site-directed mutagenesis of acidic/basic residues, in vitro GTP release assay, nuclear import assay in permeabilized cells, wheat germ agglutinin inhibition\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis combined with in vitro functional assays and cellular import assays in one study\",\n      \"pmids\": [\"11733047\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The Mog1-Ran interaction interface involves conserved Mog1 residues Asp62 and Glu65, and Ran residue Lys136; mutations at these residues decrease Mog1's ability to bind and release nucleotide from Ran, and cause temperature sensitivity and mislocalization of a nuclear import reporter protein in yeast, demonstrating that Mog1-Ran interaction is necessary for efficient nuclear protein import in vivo. MOG1 shows synthetic lethality with PRP20 (RanGEF).\",\n      \"method\": \"Site-directed mutagenesis, in vitro binding and GTP release assay, yeast genetics (synthetic lethality, nuclear import reporter mislocalization)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis with both in vitro and in vivo functional validation, synthetic lethality epistasis\",\n      \"pmids\": [\"11509570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Human MOG1 protein binds to both yeast and human Ran, is concentrated within the nucleus (but also present throughout the cell), and can partially complement growth defects in yeast MOG1-deletion cells, indicating functional conservation of the Ran-binding and nuclear trafficking roles.\",\n      \"method\": \"Co-immunoprecipitation / binding assay (yeast and human Ran), subcellular localization (immunofluorescence), yeast complementation assay\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding assays and complementation in a single study, single lab\",\n      \"pmids\": [\"11290418\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"In yeast, Mog1 deletion dislocates phospholipid N-methyltransferase Opi3p from the nuclear membrane; fission yeast mog1(ts) causes nuclear accumulation of mRNA and is rescued by Cid13 (poly-A polymerase for suc22 mRNA), Crp79 (mRNA export factor), and Ssp1 (stress-response kinase). SpMog1 co-precipitates with Nxt2 and Cid13, implicating Mog1 in mRNA export.\",\n      \"method\": \"Suppressor screen (multi-copy rescue), fluorescence microscopy (mRNA export assay), co-immunoprecipitation\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic suppressor screen plus co-IP, but single lab, yeast model\",\n      \"pmids\": [\"17651922\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MOG1 interacts with the cytoplasmic Loop II (between transmembrane domains DII and DIII) of Nav1.5, as identified by yeast two-hybrid, GST pull-down, and co-immunoprecipitation in HEK293 cells and native cardiac cells. Co-expression of MOG1 with Nav1.5 increases sodium current density and cell-surface expression of Nav1.5. MOG1 co-localizes with Nav1.5 at the intercalated discs and plasma membrane of cardiomyocytes.\",\n      \"method\": \"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, patch-clamp electrophysiology, Western blot (surface expression), immunofluorescence/confocal microscopy\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (Y2H, pulldown, Co-IP, electrophysiology, surface expression, localization) in single study, replicated by subsequent independent labs\",\n      \"pmids\": [\"18184654\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The MOG1 missense mutation E83D (Brugada syndrome patient) fails to increase sodium current density when overexpressed and exerts a dominant-negative effect on wild-type MOG1 function; Nav1.5 fails to traffic properly to the cell membrane in the presence of E83D-MOG1. Silencing endogenous MOG1 with siRNA reduced INa density by 54%.\",\n      \"method\": \"Patch-clamp electrophysiology, siRNA knockdown, microscopy (trafficking), overexpression in HEK-Nav1.5 stable cells\",\n      \"journal\": \"Circulation. Cardiovascular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis-based functional assay (patch-clamp + trafficking microscopy + siRNA KD) in well-controlled heterologous expression system\",\n      \"pmids\": [\"21447824\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The nonsense variant p.E61X in MOG1/RANGRF completely eliminates the sodium current-increasing effect of MOG1 when expressed in CHO-K1 cells co-expressing Nav1.5; mimicking heterozygosity by co-expression with wild-type MOG1 did not reduce current, indicating no dominant-negative effect for this variant.\",\n      \"method\": \"Patch-clamp electrophysiology in CHO-K1 cells, co-expression with Nav1.5\",\n      \"journal\": \"The Canadian journal of cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiological assay, single lab, single method\",\n      \"pmids\": [\"21621375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MOG1 knockdown (siRNA) causes retention of Nav1.5 in the endoplasmic reticulum, disrupts the distribution of Nav1.5 into caveolin-3-enriched microdomains, and reduces plasma membrane expression and INa density. MOG1 does not affect Nav1.5 plasma membrane turnover. MOG1 overexpression rescues reduced plasma membrane expression and INa for the trafficking-defective Nav1.5 mutations D1275N and G1743R.\",\n      \"method\": \"siRNA knockdown, cell surface protein quantification, patch-clamp electrophysiology, subcellular fractionation/immunofluorescence (ER retention, caveolin-3 microdomains), overexpression rescue assay\",\n      \"journal\": \"Circulation. Arrhythmia and electrophysiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (siRNA, surface expression quantification, compartment analysis, electrophysiology, rescue assay) in a single well-controlled study\",\n      \"pmids\": [\"23420830\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Knockdown of mog1 in zebrafish embryos decreases heart rate and causes abnormal cardiac looping during embryogenesis; overexpression of human MOG1 increases heart rate. Mechanistically, mog1 knockdown reduces expression of hcn4 (pacemaker channel), nkx2.5, gata4, and hand2 (cardiac morphogenesis transcription factors).\",\n      \"method\": \"Zebrafish morpholino knockdown, mog1 mRNA overexpression, heart rate measurement, whole-mount imaging, RT-PCR/gene expression analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with specific phenotypic readout and downstream gene expression analysis, single lab\",\n      \"pmids\": [\"26903377\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The MOG1 domain required for interaction with Nav1.5 maps to amino acids 146–155, with Asp148, Arg150, and Ser151 forming a peptide loop essential for Nav1.5 binding. The BrS-associated substitution E83D and mutations D148Q, R150Q, S151Q disrupt MOG1-Nav1.5 interaction and significantly reduce Nav1.5 trafficking to the cell surface. Structural analysis indicates that Glu83 and the loop containing Asp148/Arg150/Ser151 are spatially proximal, forming a critical Nav1.5 binding site.\",\n      \"method\": \"Large deletion analysis, alanine-scanning mutagenesis, site-directed mutagenesis, GST pull-down, patch-clamp electrophysiology, cell surface protein quantification, 3D structural analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic deletion + mutagenesis + pull-down + electrophysiology + structural analysis in one study\",\n      \"pmids\": [\"30282806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In Saccharomyces cerevisiae, Mog1 is required to sustain normal levels of histone H2B monoubiquitination (H2Bub1) and H3K4me3; Mog1 is needed for gene-body recruitment of Rad6, Bre1, and Rtf1 (H2B ubiquitination machinery). Mog1 co-precipitates with Bre1, Rtf1, and COMPASS-associated factors Shg1 and Sdc1. Loss of MOG1 impacts transcription, DNA replication, and mRNA export linked to H2Bub1.\",\n      \"method\": \"ChIP, co-immunoprecipitation, genetic interaction analysis, mRNA export assay, chromatin immunoprecipitation\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and Co-IP in yeast model, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"30249596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Mog1 knockout zebrafish develop cardiac hypertrophy and heart failure. Mechanistically, mog1 knockout decreases tbx5 expression, which reduces cryab and hspb2 expression, causing cardiac hypertrophy; overexpression of cryab, hspb2, or tbx5 rescues the cardiac edema phenotype. Mog1 KO also causes QRS and QTc prolongation, reduced heart rate associated with reduced scn1b expression, and abnormal cardiac looping associated with reduced nkx2.5, gata4, and hand2 expression.\",\n      \"method\": \"TALEN-generated knockout zebrafish, echocardiography, RNA-seq, KEGG pathway analysis, RT-PCR, rescue by overexpression (cryab, hspb2, tbx5), whole-mount in situ hybridization, telemetry ECG\",\n      \"journal\": \"Acta physiologica (Oxford, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with epistasis (rescue experiments), multiple phenotypic readouts, single lab\",\n      \"pmids\": [\"33032360\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The MOG1-Nav1.5 interaction domain on Nav1.5 maps to Loop I (connecting transmembrane domains I and II), specifically to the five-amino-acid motif F530-T531-F532-R533-R534; mutations F530A, F532A, R533A, and R534A significantly reduce MOG1-Nav1.5 interaction and eliminate MOG1-enhanced INa. On the MOG1 side, residues D24, E36, D44, E53, and E101 are critical for interaction with Nav1.5 Loop I. BrS-associated mutation p.F532C abolishes Nav1.5 interaction with MOG1 and reduces MOG1-enhanced INa.\",\n      \"method\": \"Large deletion analysis, microdeletion analysis, site-directed mutagenesis, GST pull-down, co-immunoprecipitation, cell surface protein quantification, patch-clamp electrophysiology\",\n      \"journal\": \"Heart rhythm\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic deletion + point mutagenesis + pull-down + Co-IP + surface expression + electrophysiology in one study\",\n      \"pmids\": [\"34843967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"AAV9-mediated MOG1 gene therapy in a Scn5a knock-in Brugada syndrome mouse model increased cell surface expression of Nav1.5, increased ventricular INa, reversed upregulation of Kcnd3 and Cacna1c, normalized cardiac action potentials, abolished J waves, and blocked ventricular tachyarrhythmias. MOG1 acts as a chaperone that binds Nav1.5 and traffics it to the cell surface.\",\n      \"method\": \"AAV9 gene delivery in knock-in mouse model, patch-clamp electrophysiology, ECG, Western blot (surface expression), action potential recording\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo gene therapy rescue in KI mouse model with multiple orthogonal phenotypic readouts, replicated across two mouse models\",\n      \"pmids\": [\"35675436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Mog1-/- (knockout) mice exhibit prolonged QRS duration, LV systolic dysfunction, increased ventricular fibrosis, and isoproterenol-induced arrhythmias and sudden death. Notably, cardiac expression and function of Nav1.5 are normal in Mog1-/- mice at baseline. Mog1 deficiency reduces cardiac Cx43 (Gja1) expression and impairs gap-junction function; treatment with Cx43 gap-junction enhancer ZP123 decreased arrhythmia inducibility. Mog1 KO also dysregulates Mmp2, mitochondrial dynamics, and increases ATP supply.\",\n      \"method\": \"Mog1 knockout mouse, whole-cell patch-clamp, RNA-seq, iTRAQ proteomics, RT-qPCR, Western blot, immunofluorescence, dye transfer assay (gap junction function), transmission electron microscopy, isoproterenol challenge\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple orthogonal methods (electrophysiology, proteomics, transcriptomics, gap junction assay, EM, pharmacological rescue), single lab\",\n      \"pmids\": [\"35533905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The MOG1-Nav1.5 interaction domain in Nav1.5 Loop II (residues 940–1200) maps to V1190-H1200; point mutations reveal R1195, Y1199, and H1200 as critical for MOG1-Nav1.5 Loop II interaction. Patient variants p.R1195C and p.Y1199S weaken MOG1-Nav1.5 interaction and reduce MOG1-enhanced INa; p.Y1199S additionally generates late INa. These variants are associated with LQTS and cardiac arrhythmias.\",\n      \"method\": \"Large deletion analysis, small deletion analysis, site-directed mutagenesis, GST pull-down, patch-clamp electrophysiology (INa and late INa) in tsA201 cells and neonatal rat cardiomyocytes\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic mutagenesis + pull-down + electrophysiology in one study with patient variant functional validation\",\n      \"pmids\": [\"40543898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MOG1 variant L18F (identified in a LQTS proband) increases late sodium current (INaL) and enhances NaV1.8 expression at the sarcolemma in ventricular cardiomyocytes; this prolongs action potential duration and causes EADs, DADs, and triggered activity. The NaV1.8 inhibitor A-803467 reversed the cellular electrophysiological effects of MOG1L18F and reduced arrhythmia inducibility in vivo. NaV1.8 interacts with both MOG1 and NaV1.5.\",\n      \"method\": \"AAV9-mediated cardiac-specific mouse model, surface ECG, programmed electrical stimulation, optical mapping, patch-clamp (INaL, action potential), Ca2+ dynamics, Western blot/immunofluorescence (surface NaV1.8), pharmacological inhibition (A-803467)\",\n      \"journal\": \"medRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — preprint, multiple orthogonal methods (in vivo mouse model, electrophysiology, pharmacological rescue), single lab, not yet peer-reviewed\",\n      \"pmids\": [\"41445668\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"RANGRF/MOG1 is a small, evolutionarily conserved nuclear protein that functions both as a Ran GTPase guanine nucleotide release factor—binding RanGTP via a conserved acidic loop (Asp25/Asp34/Glu37 in yeast; Asp62/Glu65 in the Ran interface) to stimulate GTP release and facilitate nuclear protein import—and as a dedicated chaperone for the cardiac sodium channel Nav1.5, physically interacting with Nav1.5 at Loop I (F530–R534 motif) and Loop II (R1195/Y1199/H1200) to promote Nav1.5 trafficking from the ER through caveolin-3-enriched microdomains to the plasma membrane, thereby increasing INa density; loss-of-function mutations (E83D, E61X) or knockdown reduce Nav1.5 surface expression and INa causing Brugada syndrome, while a gain-of-function variant (L18F) increases late INa via NaV1.8 upregulation causing Long QT syndrome, and in vivo MOG1 additionally regulates cardiac morphogenesis, gap junction (Cx43) function, and a tbx5–cryab–hspb2 signaling axis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RANGRF (MOG1) is a small, evolutionarily conserved nuclear protein that operates as a Ran GTPase guanine nucleotide release factor and, in cardiac tissue, as a dedicated trafficking chaperone for the voltage-gated sodium channel Nav1.5 [#0, #5]. In its Ran-related role, MOG1 binds RanGTP and stimulates GTP release, then remains bound to nucleotide-free Ran to block guanine-nucleotide rebinding, a mechanism distinct from the canonical RanGEF [#0]; a conserved solvent-exposed acidic loop (Asp25/Asp34/Glu37) and interface residues Asp62/Glu65 mediate this activity, and disruption of the MOG1–Ran interaction impairs nuclear protein import in vivo [#1, #2]. Independent of its Ran activity, MOG1 binds Nav1.5 through cytoplasmic Loop I (the F530–R534 motif) and Loop II (R1195/Y1199/H1200), using a discrete MOG1 surface that includes Glu83 and a Asp148/Arg150/Ser151 loop, and drives Nav1.5 trafficking out of the endoplasmic reticulum through caveolin-3-enriched microdomains to the plasma membrane, thereby raising sodium current (INa) density [#5, #8, #10, #13, #16]. Loss-of-function MOG1 variants (E83D, E61X) and knockdown trap Nav1.5 in the ER and reduce surface expression and INa, causing Brugada syndrome, whereas variants weakening the Loop II interaction (R1195C, Y1199S) and the L18F variant prolong repolarization and cause Long QT syndrome [#6, #7, #13, #16]; AAV9-delivered MOG1 restores Nav1.5 surface expression and suppresses arrhythmias in a Brugada mouse model [#14]. Beyond channel trafficking, MOG1 governs cardiac morphogenesis and contractile homeostasis: it supports Cx43 gap-junction function [#15] and a tbx5–cryab–hspb2 axis whose loss produces cardiac hypertrophy and looping defects [#9, #12]. In yeast, MOG1 additionally contributes to mRNA export and to histone H2B monoubiquitination/H3K4me3 via recruitment of Rad6/Bre1/Rtf1 [#4, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing MOG1's biochemical activity answered whether it acts in the Ran cycle, showing it is a non-canonical guanine nucleotide release factor that locks Ran nucleotide-free.\",\n      \"evidence\": \"In vitro GTP release and RanGTP binding assays with mammalian Mog1\",\n      \"pmids\": [\"10811801\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular consequence of Ran-nucleotide release not yet linked to a specific import cargo\", \"Structure of the Mog1-Ran complex not resolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Mutagenesis and in vivo yeast genetics mapped the Ran-binding determinants and established that MOG1-Ran interaction is required for efficient nuclear protein import.\",\n      \"evidence\": \"Site-directed mutagenesis (Asp25/Asp34/Glu37, Asp62/Glu65), in vitro GTP release, permeabilized-cell import assay, yeast synthetic lethality with PRP20 and import-reporter mislocalization\",\n      \"pmids\": [\"11733047\", \"11509570\", \"11290418\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of physiological import cargoes incomplete\", \"How MOG1 nucleocytoplasmic shuttling is regulated unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Yeast genetic and co-IP analyses extended MOG1 function beyond import into nuclear membrane organization and mRNA export.\",\n      \"evidence\": \"Multi-copy suppressor screen, mRNA export microscopy, co-IP with Nxt2/Cid13 in fission yeast\",\n      \"pmids\": [\"17651922\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct mechanism connecting MOG1 to mRNA export machinery unresolved\", \"Conservation of mRNA-export role in mammals not tested\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identification of a physical MOG1-Nav1.5 interaction defined an entirely new, cardiac-specific function as a sodium-channel trafficking partner.\",\n      \"evidence\": \"Yeast two-hybrid, GST pull-down, co-IP in HEK293 and cardiac cells, patch-clamp, surface biotinylation, confocal localization to intercalated discs\",\n      \"pmids\": [\"18184654\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the Ran and Nav1.5 functions are mechanistically coupled unaddressed\", \"Initial mapping limited to Loop II\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Functional testing of patient variants showed loss of MOG1 trafficking activity causes Brugada syndrome, with E83D acting dominant-negatively and E61X without dominant-negative effect.\",\n      \"evidence\": \"Patch-clamp, siRNA knockdown, trafficking microscopy in HEK-Nav1.5 and CHO-K1 co-expression systems\",\n      \"pmids\": [\"21447824\", \"21621375\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the E83D dominant-negative effect not defined here\", \"Variant penetrance and modifier effects in patients not addressed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defining the trafficking step established that MOG1 promotes Nav1.5 ER exit and entry into caveolin-3 microdomains rather than affecting membrane turnover.\",\n      \"evidence\": \"siRNA knockdown, surface protein quantification, subcellular fractionation, patch-clamp, rescue of trafficking-defective Nav1.5 mutants\",\n      \"pmids\": [\"23420830\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular machinery linking MOG1 to ER export not identified\", \"Role of caveolin-3 interaction direct vs indirect unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Whole-organism loss-of-function revealed a developmental cardiac role beyond channel trafficking, linking MOG1 to heart rate and morphogenesis gene expression.\",\n      \"evidence\": \"Zebrafish morpholino knockdown and mRNA overexpression, heart-rate measurement, hcn4/nkx2.5/gata4/hand2 expression analysis\",\n      \"pmids\": [\"26903377\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether morphogenesis defects are channel-dependent or independent unclear\", \"Direct vs indirect control of transcription factors not established\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Systematic mapping localized the Nav1.5-binding surface on MOG1 to a spatially proximal Glu83/Asp148-Arg150-Ser151 site, mechanistically explaining how the BrS E83D variant disrupts trafficking.\",\n      \"evidence\": \"Deletion and alanine-scanning mutagenesis, GST pull-down, patch-clamp, surface quantification, 3D structural analysis\",\n      \"pmids\": [\"30282806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full atomic structure of the MOG1-Nav1.5 complex still lacking\", \"Relationship of this surface to the Ran-binding loop not resolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Yeast chromatin studies uncovered a conserved role for MOG1 in promoting H2B monoubiquitination and H3K4me3 via recruitment of the Rad6/Bre1/Rtf1 machinery.\",\n      \"evidence\": \"ChIP, co-IP with Bre1/Rtf1/Shg1/Sdc1, genetic interaction and mRNA export assays in S. cerevisiae\",\n      \"pmids\": [\"30249596\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the chromatin role is conserved in mammals untested\", \"Direct vs Ran-dependent contribution to chromatin marks unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Mapping the Nav1.5 Loop I motif (F530-R534) and the reciprocal MOG1 acidic residues defined a second, structurally specific binding interface whose disruption (e.g., F532C) causes Brugada syndrome.\",\n      \"evidence\": \"Deletion and point mutagenesis, GST pull-down, co-IP, surface quantification, patch-clamp\",\n      \"pmids\": [\"34843967\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Loop I and Loop II interactions cooperate during trafficking unresolved\", \"Stoichiometry of the MOG1-Nav1.5 complex unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"In vivo gene therapy demonstrated MOG1 restoration is sufficient to correct the Brugada phenotype, confirming its causal trafficking-chaperone role and therapeutic potential.\",\n      \"evidence\": \"AAV9-MOG1 delivery in Scn5a knock-in mice, patch-clamp, ECG, surface Western blot, action potential recording\",\n      \"pmids\": [\"35675436\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Durability and off-target effects of gene therapy not addressed\", \"Translation to human BrS untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Constitutive knockout mice revealed Nav1.5-independent cardiac functions, implicating MOG1 in Cx43 gap-junction integrity, fibrosis, and mitochondrial dynamics.\",\n      \"evidence\": \"Mog1 KO mouse, patch-clamp, RNA-seq, iTRAQ proteomics, gap-junction dye transfer, EM, ZP123 pharmacological rescue, isoproterenol challenge\",\n      \"pmids\": [\"35533905\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking MOG1 to Cx43 expression unknown\", \"Why baseline Nav1.5 is normal in KO yet siRNA reduces INa unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Mapping the Loop II interaction site and characterizing LQTS patient variants showed that weakened MOG1-Nav1.5 binding and late-INa generation underlie Long QT phenotypes.\",\n      \"evidence\": \"Deletion and point mutagenesis (R1195/Y1199/H1200), GST pull-down, patch-clamp (INa and late INa) in tsA201 cells and neonatal rat cardiomyocytes\",\n      \"pmids\": [\"40543898\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which Y1199S generates late INa not defined\", \"Genotype-phenotype relationship across variants incomplete\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Characterization of the gain-of-function L18F variant connected MOG1 to NaV1.8 upregulation as an arrhythmogenic mechanism in Long QT syndrome.\",\n      \"evidence\": \"AAV9 cardiac mouse model, ECG, programmed stimulation, optical mapping, patch-clamp (INaL), surface NaV1.8 detection, A-803467 inhibition (preprint)\",\n      \"pmids\": [\"41445668\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Mechanism by which MOG1 L18F upregulates NaV1.8 unknown\", \"Direct vs indirect MOG1-NaV1.8 interaction not fully defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MOG1's ancestral Ran/nuclear-import and chromatin functions mechanistically relate to its cardiac channel-chaperone and gap-junction roles remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of the full MOG1-Nav1.5 complex\", \"Whether nuclear and cardiac functions share a common molecular surface unknown\", \"Discrepancy between knockdown and knockout effects on baseline Nav1.5 unexplained\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [5, 8, 10, 13, 16]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [5, 8, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 2, 8]},\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [14, 15, 16]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RAN\", \"SCN5A\", \"SCN10A\", \"GJA1\", \"BRE1\", \"RTF1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}