{"gene":"UNC93B1","run_date":"2026-06-10T10:51:56","timeline":{"discoveries":[{"year":2006,"finding":"Loss-of-function UNC93B1 mutations in humans result in impaired cellular IFN-α/β and IFN-λ antiviral responses, establishing UNC93B1 as essential for TLR3/7/9-dependent antiviral signaling in vivo.","method":"Human genetic study; functional assays in patient cells (interferon response measurements)","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — patient loss-of-function mutations with functional cellular readout, replicated across multiple independent studies","pmids":["16973841"],"is_preprint":false},{"year":2006,"finding":"A missense mutation (H412R) in Unc93b1 ('3d' mutation) abolishes signaling through intracellular TLR3, TLR7, and TLR9, and also impairs cross-presentation and MHC class II presentation of exogenous antigen; UNC93B1 was identified as a 12-transmembrane-spanning ER-resident protein.","method":"ENU mutagenesis screen; positional cloning; functional TLR signaling assays; antigen presentation assays in dendritic cells","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — positional cloning with functional validation, replicated across multiple subsequent studies","pmids":["16415873"],"is_preprint":false},{"year":2008,"finding":"UNC93B1 physically interacts with TLR7 and TLR9 in the ER and delivers them to endolysosomes; the H412R mutation prevents TLR binding and blocks ER exit of TLR7 and TLR9, while wild-type UNC93B1 rescues trafficking and signaling defects in 3d dendritic cells.","method":"Co-immunoprecipitation; subcellular fractionation; live-cell imaging; genetic complementation in 3d dendritic cells","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, subcellular localization, functional rescue, replicated across multiple labs","pmids":["18305481"],"is_preprint":false},{"year":2009,"finding":"UNC93B1 residue D34 represses TLR7-mediated responses while favoring TLR9; D34A mutation increases Unc93B1 association with TLR7 and ligand-induced TLR7 trafficking while decreasing TLR9 association and trafficking, biasing nucleic acid sensing toward DNA-sensing in dendritic cells.","method":"Complementation cloning; co-immunoprecipitation; endolysosomal trafficking assays; TLR signaling assays with TLR-specific ligands","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — mutagenesis combined with Co-IP, trafficking assays, and signaling readouts; replicated in subsequent studies","pmids":["19451267"],"is_preprint":false},{"year":2010,"finding":"UNC93B1 interacts directly with TLR11 in the ER and is required for TLR11-dependent IL-12 secretion and dendritic cell activation in response to Toxoplasma gondii profilin, demonstrating that UNC93B1 interaction and intracellular localization are not unique to nucleic acid-sensing TLRs.","method":"Co-immunoprecipitation; subcellular localization; IL-12 secretion assays; in vivo infection model with UNC93B1-deficient mice","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct Co-IP with functional in vitro and in vivo readouts","pmids":["21097503"],"is_preprint":false},{"year":2011,"finding":"TLR9 competes with TLR7 for UNC93B1-dependent trafficking and predominates; a D34A mutation in UNC93B1 reverses this balance toward TLR7, causing TLR7-dependent systemic lethal inflammation in mice driven by CD4+ T cell Th1/Th17 differentiation and B cell activity.","method":"Knock-in mouse model (D34A); TLR competition assays; flow cytometry; B cell depletion experiments","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic model with mechanistic dissection using cell depletion, replicated concept from earlier biochemical studies","pmids":["21683627"],"is_preprint":false},{"year":2013,"finding":"UNC93B1 enters the secretory pathway and directly controls packaging of TLRs into COPII vesicles budding from the ER; it remains associated with TLRs through post-Golgi sorting. TLR9 requires UNC93B1-mediated AP-2 recruitment for endolysosomal delivery, while TLR7, TLR11, TLR12, and TLR13 use alternative trafficking pathways.","method":"COPII vesicle budding assays; co-immunoprecipitation; AP complex interaction assays; subcellular trafficking analysis","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro COPII budding reconstitution combined with multiple trafficking assays and receptor-specific mechanistic dissection","pmids":["23426999"],"is_preprint":false},{"year":2013,"finding":"Acidic residues D812/E813 of TLR9 and D699/E704 of TLR3 in the juxtamembrane region are required for UNC93B1 binding; mutation of these residues prevents UNC93B1 interaction, impairs TLR trafficking from the ER, and abolishes TLR signaling.","method":"Site-directed mutagenesis of TLR juxtamembrane residues; co-immunoprecipitation; subcellular localization; signaling assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis with multiple functional readouts (binding, trafficking, signaling), single lab","pmids":["23585677"],"is_preprint":false},{"year":2014,"finding":"UNC93B1 is essential for plasma membrane localization and signaling of TLR5 (a flagellin receptor); TLR5 physically interacts with UNC93B1, and cells from 3d or UNC93B1-deficient mice lack TLR5 at the plasma membrane and fail to produce cytokines upon flagellin stimulation.","method":"Co-immunoprecipitation; cell surface localization assays; cytokine secretion and costimulatory molecule upregulation in 3d and UNC93B1-KO cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP plus localization plus functional readout in genetic mouse models, confirmed with multiple cell types","pmids":["24778236"],"is_preprint":false},{"year":2014,"finding":"A C-terminal tyrosine-based sorting motif (YxxΦ) in UNC93B1 differentially regulates TLR7, TLR8, and TLR9 activity toward nucleic acid ligands in human B cells and monocytes; destruction of YxxΦ abolishes these TLR responses. YxxΦ controls UNC93B1 subcellular localization via both AP1- and AP2-dependent pathways, but loss of AP function does not recapitulate altered TLR responses, indicating AP-independent functions.","method":"Site-directed mutagenesis of UNC93B1 YxxΦ motif; TLR signaling assays in human primary cells; AP complex knockdown; subcellular localization imaging","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — mutagenesis with functional signaling readouts in primary human cells and multiple orthogonal approaches","pmids":["25187660"],"is_preprint":false},{"year":2011,"finding":"UNC93B1 physically associates with human TLR8 and is required for TLR8-mediated signaling; TLR8 localizes to early endosomes and ER but not late endosomes or lysosomes, and the transmembrane domain and TIR domain of TLR8 are required for proper early endosomal targeting.","method":"Co-immunoprecipitation; subcellular localization (confocal microscopy with organelle markers); TLR8 signaling assays; truncation mutant analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with localization and signaling readout, single lab with multiple methods","pmids":["22164301"],"is_preprint":false},{"year":2015,"finding":"LRRC59, an ER membrane protein, associates with UNC93B1 upon ligand stimulation (in a TLR-independent manner requiring signals from ligand internalization) and promotes UNC93B1-mediated translocation of TLR3, TLR8, and TLR9 from the ER to endosomes.","method":"Co-immunoprecipitation (ligand-induced); siRNA knockdown of LRRC59; subcellular localization of endogenous TLR3; TLR signaling assays","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with KD functional readouts and localization, single lab","pmids":["26466955"],"is_preprint":false},{"year":2017,"finding":"UNC93B1 interacts with the ER calcium sensor STIM1, and this interaction is required for STIM1 oligomerization and activation; UNC93B1 deficiency impairs endosomal acidification, phagosomal maturation, antigen degradation, antigen export to the cytosol, and STIM1 function, resulting in compromised antigen cross-presentation. Expression of a constitutively active STIM1 mutant that does not bind UNC93B1 restores antigen degradation and cross-presentation in 3d-mutated DCs.","method":"Co-immunoprecipitation (UNC93B1-STIM1); constitutively active STIM1 mutant rescue; antigen cross-presentation assays; calcium flux measurements in 3d DCs","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP with functional rescue experiment using mutant STIM1, multiple cellular readouts, and genetic complementation","pmids":["29158474"],"is_preprint":false},{"year":2018,"finding":"UNC93B1 deficiency causes near-complete loss of TLR3 and TLR7 proteins in primary dendritic cells and macrophages, demonstrating that UNC93B1 is critical for TLR protein stability upstream of trafficking; expression of an ER-retained UNC93B1 version is sufficient to stabilize TLRs and largely restore endosomal TLR trafficking and activity.","method":"Western blot of TLR protein levels in UNC93B1-KO vs WT primary cells; ER-retained UNC93B1 mutant rescue experiments; TLR signaling assays","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with quantitative protein level measurements, mechanistic rescue with ER-retained mutant, primary cell experiments","pmids":["29768176"],"is_preprint":false},{"year":2019,"finding":"UNC93B1 specifically limits TLR7 (but not TLR9) signaling by recruiting syntenin-1; UNC93B1 mutations that enhance TLR7 signaling disrupt syntenin-1 binding. UNC93B1 and TLR7 are detectable in exosomes, suggesting UNC93B1-syntenin-1 interaction facilitates sorting of TLR7 into intralumenal vesicles of multivesicular bodies to terminate signaling. Phosphorylation of UNC93B1 is required for syntenin-1 binding.","method":"Co-immunoprecipitation; exosome fractionation and Western blot; mutagenesis; phosphorylation analysis; TLR7-specific autoimmunity in knock-in mice","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP with biochemical and genetic evidence, exosome localization data, in vivo autoimmunity model, multiple orthogonal methods in one study","pmids":["31546246"],"is_preprint":false},{"year":2019,"finding":"TLR9 (and TLR3) are released from UNC93B1 within endosomes, and this release is required for ligand binding and signal transduction; UNC93B1 mutations that increase TLR9 affinity or an artificial tether preventing release block TLR9 signaling. TLR7 does not dissociate from UNC93B1 in endosomes and is regulated by distinct mechanisms.","method":"Co-immunoprecipitation at different pH/compartments; tethered UNC93B1-TLR9 fusion constructs; affinity-increasing mutations; TLR signaling assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — biochemical dissection with engineered tether and affinity mutations, multiple orthogonal methods establishing mechanism","pmids":["31546247"],"is_preprint":false},{"year":2021,"finding":"Cryo-EM structures of human and mouse TLR3-UNC93B1 complexes and human TLR7-UNC93B1 complex reveal that UNC93B1 exhibits structural similarity to major facilitator superfamily transporters; both TLRs interact with the UNC93B1 N-terminal six-helix bundle through their transmembrane and luminal juxtamembrane regions; TLR3 and TLR7 complexes differ in their oligomerization state.","method":"Cryo-electron microscopy structural determination","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — atomic-resolution cryo-EM structures of two distinct TLR-UNC93B1 complexes from human and mouse, establishing direct interaction interface","pmids":["33432245"],"is_preprint":false},{"year":2022,"finding":"N-glycosylation of UNC93B1 at Asn272 (but not Asn251) is required for TLR9 signaling; the N272Q mutation selectively impairs MyD88 recruitment to TLR9 and downstream signaling without affecting TLR7 signaling, UNC93B1 expression, or TLR9 localization. The two N-glycosylation sites (Asn251 and Asn272) can be glycosylated independently.","method":"Site-directed mutagenesis (N251Q, N272Q); TLR9 signaling assays; co-immunoprecipitation of MyD88-TLR9; subcellular localization; TLR7 signaling comparison","journal":"Frontiers in immunology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — site-directed mutagenesis with multiple functional readouts (signaling, MyD88 recruitment, localization), single lab","pmids":["35874766"],"is_preprint":false},{"year":2022,"finding":"UNC93B1 attenuates cGAS-STING signaling by directly interacting with STING and delivering it to lysosomes for autophagy-dependent degradation; UNC93B1 knockout enhances STING-dependent IFN-β production and reduces STING protein degradation. This function depends on UNC93B1 trafficking capability.","method":"Co-immunoprecipitation (UNC93B1-STING); UNC93B1 overexpression and knockout; lysosome inhibitor rescue; IFN-β promoter assays; IRF3 nuclear translocation; HSV-1 infection in KO mice","journal":"Journal of medical virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with KO functional data and in vivo confirmation, single lab, partially replicated by independent study (PMID 33837956)","pmids":["35577759"],"is_preprint":false},{"year":2021,"finding":"UNC93B1 directly interacts with STING and promotes STING protein degradation; UNC93B1 deficiency blunts TLR3 signaling but augments innate immune responses to cytosolic DNA stimulation by causing STING accumulation, demonstrating a negative regulatory role on STING-mediated signaling.","method":"Co-immunoprecipitation (UNC93B1-STING); UNC93B1 knockdown/KO; cytosolic DNA stimulation assays; STING protein level measurement","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with KO functional readouts, single lab, corroborated by independent study (PMID 35577759)","pmids":["33837956"],"is_preprint":false},{"year":2022,"finding":"UNC93B1 interacts with STIM1 in the ER lumen near the transmembrane domain; UNC93B1 binding promotes zipping of transmembrane and proximal cytosolic helices within resting STIM1 dimers, priming them for translocation. UNC93B1 deficiency reduces store-operated Ca2+ entry, STIM1-Orai1 interactions, and targets STIM1 to lighter ER domains; UNC93B1 expression accelerates STIM1 recruitment to cortical ER domains.","method":"Co-immunoprecipitation; cysteine crosslinking in vivo; calcium flux measurements; STIM1-Orai1 Co-IP; subcellular fractionation; live-cell imaging","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — cysteine crosslinking plus Co-IP plus functional calcium measurements, multiple orthogonal methods, directly extends prior finding (PMID 29158474)","pmids":["35065962"],"is_preprint":false},{"year":2012,"finding":"UNC93B1 promotes trafficking of differentially glycosylated TLR3 (but not other NA-sensing TLRs) to the plasma membrane in human epithelial cells; poly(I:C) up-regulates UNC93B1 transcription via TLR3 activation; UNC93B1 increases protein lifetime of TLR3 and TLR9 and augments signaling of all NA-sensing TLRs. Poly(I:C) pretreatment primes B cells to ssDNA activation via UNC93B1 up-regulation.","method":"siRNA knockdown; confocal microscopy for TLR3 localization; Western blot for protein stability; TLR signaling assays; UNC93B1 promoter analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple readouts (localization, stability, signaling) in single lab with siRNA and overexpression approaches","pmids":["23166319"],"is_preprint":false},{"year":2003,"finding":"In C. elegans, UNC-93 colocalizes with SUP-9 (a two-pore K+ channel) and SUP-10 within muscle cells, and genetic evidence suggests these three proteins form a multisubunit complex coordinating muscle contraction; UNC-93 defines a novel multigene family conserved in C. elegans, Drosophila, and humans.","method":"Genetic epistasis analysis; cloning of sup-9 and sup-10; colocalization by immunofluorescence in muscle cells","journal":"The Journal of neuroscience","confidence":"Low","confidence_rationale":"Tier 3 / Weak — C. elegans ortholog colocalization; genetic evidence for complex but no direct biochemical reconstitution; not directly informative for mammalian UNC93B1 TLR function","pmids":["14534247"],"is_preprint":false},{"year":2024,"finding":"UNC93B1 variants E92G and R336L cause selective TLR7 hyperactivation; E92G causes UNC93B1 protein instability and reduced interaction with TLR7, leading to constitutive type I IFN signaling, while neither variant affects TLR3 or TLR9 responses, establishing UNC93B1 as a TLR subtype-specific regulator.","method":"Patient cell functional assays; mouse macrophage model with variants; co-immunoprecipitation (UNC93B1-TLR7); cytokine measurements; protein stability assays","journal":"Science immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — human patient variants with in vitro functional validation, Co-IP, and mouse model, multiple orthogonal readouts","pmids":["38207055"],"is_preprint":false},{"year":2024,"finding":"UNC93B1 variants I317M, G325C cause gain of TLR7 and TLR8 activity in SLE patients; variants L330R, R466S, R525P cause gain of TLR8 activity in chilblain lupus patients. G325C, L330R, and R466S variants show enhanced interaction with TLR8 by Co-IP, while R525P does not, indicating different disease mechanisms for different mutations.","method":"In vitro TLR signaling assays; ex vivo patient cell assays; co-immunoprecipitation (UNC93B1 variants with TLR8)","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple patient-derived variants with TLR-specific functional assays and Co-IP, mechanistically distinct variants characterized","pmids":["38869500"],"is_preprint":false},{"year":2024,"finding":"Systematic alanine scanning mutagenesis of all cytosolic and luminal UNC93B1 residues identified distinct positive and negative regulatory regions for TLR3, TLR7, and TLR9 responses; human variants UNC93B1-T93I and UNC93B1-R336C in identified negative regulatory regions enhance TLR7/8 responses and cause systemic autoimmune disease when introduced into mice.","method":"Scanning alanine mutagenesis screen; TLR signaling assays (TLR3, TLR7/8, TLR9); CRISPR knock-in mouse models; patient variant analysis","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic mutagenesis with functional signaling readouts plus in vivo knock-in validation, comprehensive mechanistic mapping","pmids":["38780621"],"is_preprint":false},{"year":2024,"finding":"UNC93B1 variant V117L is associated with increased TLR7/8 (but not TLR3/TLR9) responses; variant T314A (proximal to TLR7 transmembrane domain) also causes exaggerated TLR7/8 responses; heterozygous mice expressing Unc93b1 V117L develop spontaneous lupus-like disease.","method":"Patient cell functional assays; THP-1 cell TLR stimulation assays; heterozygous knock-in mouse model; cytokine and IFN measurements","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — patient variants validated in cell lines and in vivo mouse model with receptor-specific functional readouts","pmids":["38831104"],"is_preprint":false},{"year":2021,"finding":"UNC93B1 is expressed in multiple CNS cell types (microglia, astrocytes, oligodendrocytes, neurons) and is required for microglial activation and neuronal injury induced by extracellular let-7b (a TLR7 activator); intrathecal let-7b causes neurodegeneration in wild-type but not UNC93B1-deficient mice.","method":"PCR, immunocytochemistry, flow cytometry for expression; TNF ELISA in UNC93B1-deficient microglia; neuronal injury assays in vitro; intrathecal injection in vivo; neurodegeneration assessment","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple cell type expression confirmed, functional KO readout in both in vitro and in vivo models, single lab","pmids":["34589086"],"is_preprint":false},{"year":2025,"finding":"PANK4 interacts with UNC93B1 to suppress TLR7 and TLR9-mediated cytokine responses, acting as a negative regulator of nucleic acid-sensing innate immune pathways.","method":"Co-immunoprecipitation (PANK4-UNC93B1); TLR7/9 signaling assays with PANK4 loss-of-function","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single Co-IP with functional readout, not yet peer-reviewed","pmids":[],"is_preprint":true}],"current_model":"UNC93B1 is a 12-transmembrane ER-resident chaperone protein that physically associates with nucleic acid-sensing TLRs (TLR3, TLR7, TLR8, TLR9, TLR11, TLR12, TLR13) and TLR5 in the ER, stabilizes them, loads them into COPII vesicles for ER exit, and differentially traffics them to endolysosomes (or the plasma membrane for TLR5) via receptor-specific mechanisms including AP-2 recruitment for TLR9; it also controls the balance of TLR7 vs. TLR9 signaling through preferential binding regulated by residue D34, terminates TLR7 signaling by recruiting syntenin-1 (in a phosphorylation-dependent manner) to sort TLR7 into multivesicular body intralumenal vesicles, enforces compartmentalized TLR9 activation by releasing TLR9 (but not TLR7) only within endosomes, negatively regulates cGAS-STING signaling by interacting with STING and promoting its lysosomal degradation, and interacts with STIM1 in the ER to prime it for store-operated calcium entry, thereby linking TLR trafficking to calcium signaling and antigen cross-presentation."},"narrative":{"mechanistic_narrative":"UNC93B1 is a polytopic ER membrane protein that serves as the master chaperone and trafficking regulator for nucleic-acid-sensing and select other Toll-like receptors, and is essential for TLR3/7/9-dependent type I/III interferon antiviral immunity in humans [PMID:16973841, PMID:16415873]. It physically binds nascent TLRs in the ER—engaging acidic juxtamembrane residues of TLR9 and TLR3 and contacting the transmembrane and luminal juxtamembrane regions of TLR3 and TLR7 through its N-terminal six-helix bundle, with an overall fold resembling major facilitator superfamily transporters [PMID:23585677, PMID:33432245]—and stabilizes TLR protein, such that its loss causes near-complete depletion of TLR3 and TLR7 even before trafficking [PMID:29768176]. UNC93B1 then escorts these receptors out of the ER by packaging them into COPII vesicles and directing them through the secretory pathway to distinct destinations: endolysosomes for TLR7/9/11/13 and the plasma membrane for the flagellin receptor TLR5, using receptor-specific routes including AP-2 recruitment for TLR9 and a C-terminal Yxxϕ sorting motif [PMID:23426999, PMID:24778236, PMID:25187660]. Beyond delivery, UNC93B1 sets the balance and intensity of TLR signaling: residue D34 represses TLR7 while favoring TLR9, and disruption of this balance toward TLR7 drives systemic autoimmune inflammation in mice [PMID:19451267, PMID:21683627]. It terminates TLR7 signaling by recruiting syntenin-1 in a phosphorylation-dependent manner to sort TLR7 into multivesicular-body intralumenal vesicles, whereas TLR9 (and TLR3) must be released from UNC93B1 within endosomes to bind ligand and signal, enforcing receptor-specific, compartmentalized activation [PMID:31546246, PMID:31546247]. A spectrum of human UNC93B1 variants that selectively enhance TLR7 and/or TLR8 activity cause systemic lupus erythematosus and chilblain lupus, establishing UNC93B1 as a TLR-subtype-specific gatekeeper of autoimmunity [PMID:38207055, PMID:38869500, PMID:38780621, PMID:38831104]. UNC93B1 additionally interacts with the ER calcium sensor STIM1 to prime its activation and support store-operated calcium entry and antigen cross-presentation [PMID:29158474, PMID:35065962], and negatively regulates cGAS-STING signaling by delivering STING for lysosomal degradation [PMID:35577759, PMID:33837956].","teleology":[{"year":2006,"claim":"Established that UNC93B1 is non-redundantly required for intracellular TLR-driven antiviral immunity, converting a then-unknown gene into a central node of innate nucleic-acid sensing.","evidence":"Human loss-of-function mutations with interferon-response assays in patient cells, and an ENU 3d (H412R) mouse mutation abolishing TLR3/7/9 signaling and antigen presentation","pmids":["16973841","16415873"],"confidence":"High","gaps":["Did not define the molecular mechanism by which UNC93B1 acts on TLRs","Localization as a 12-TM ER protein noted but interaction partners not yet mapped"]},{"year":2008,"claim":"Resolved how UNC93B1 acts mechanistically by showing it physically binds TLR7/9 in the ER and is required for their ER exit and endolysosomal delivery.","evidence":"Reciprocal Co-IP, subcellular fractionation, live imaging, and genetic complementation of 3d dendritic cells","pmids":["18305481"],"confidence":"High","gaps":["Did not identify the TLR binding interface","Did not explain receptor-specific differences in trafficking"]},{"year":2009,"claim":"Showed UNC93B1 not only traffics but biases TLR usage, identifying residue D34 as a switch repressing TLR7 in favor of TLR9.","evidence":"Complementation cloning, Co-IP, endolysosomal trafficking and TLR-ligand signaling assays of D34A mutant","pmids":["19451267"],"confidence":"High","gaps":["Physiological consequence of altered balance not yet shown in vivo","Structural basis of D34-mediated selectivity unknown"]},{"year":2011,"claim":"Demonstrated the in vivo pathological stakes of the TLR7/9 balance and broadened the client repertoire beyond nucleic-acid sensors.","evidence":"D34A knock-in mice with cell-depletion dissection showing TLR7-driven lethal inflammation; Co-IP and infection studies establishing TLR11 and TLR8 as UNC93B1-dependent","pmids":["21683627","21097503","22164301"],"confidence":"High","gaps":["Mechanism of TLR competition for UNC93B1 not defined biochemically","TLR8 finding was Medium-confidence single-lab"]},{"year":2013,"claim":"Defined the secretory-pathway logic of UNC93B1 action: COPII packaging of TLRs and receptor-specific sorting machinery, plus the TLR binding determinants.","evidence":"In vitro COPII budding reconstitution, AP-complex interaction assays, and site-directed mutagenesis of TLR9/TLR3 juxtamembrane acidic residues","pmids":["23426999","23585677"],"confidence":"High","gaps":["Alternative trafficking pathways for TLR7/11/12/13 not molecularly defined","How UNC93B1 selects AP-2 for TLR9 specifically unresolved"]},{"year":2014,"claim":"Extended UNC93B1's chaperone role to a cell-surface TLR and dissected its own sorting-motif requirements.","evidence":"Co-IP and surface-localization assays for TLR5 in 3d/KO cells; Yxxϕ motif mutagenesis with AP1/AP2 knockdown in human primary cells","pmids":["24778236","25187660"],"confidence":"High","gaps":["AP-independent functions of Yxxϕ implied but unidentified","How UNC93B1 distinguishes plasma-membrane vs endosomal destinations unclear"]},{"year":2015,"claim":"Identified an ER co-factor coupling ligand sensing to TLR translocation.","evidence":"Ligand-induced Co-IP, LRRC59 knockdown, and TLR3 localization/signaling assays","pmids":["26466955"],"confidence":"Medium","gaps":["Single-lab finding without reciprocal in vivo validation","Mechanism linking ligand internalization to LRRC59-UNC93B1 association unknown"]},{"year":2017,"claim":"Revealed a TLR-independent function: UNC93B1 partners with STIM1 to enable calcium signaling and antigen cross-presentation.","evidence":"Co-IP plus constitutively active STIM1 rescue, calcium flux and cross-presentation assays in 3d DCs","pmids":["29158474"],"confidence":"High","gaps":["Structural basis of STIM1 priming not yet resolved at this stage","Relationship between calcium role and TLR trafficking role unclear"]},{"year":2018,"claim":"Distinguished UNC93B1's stabilization function from its trafficking function, showing protein stability is the upstream requirement.","evidence":"Quantitative TLR protein measurement in KO vs WT primary cells and ER-retained UNC93B1 mutant rescue","pmids":["29768176"],"confidence":"High","gaps":["How an ER-retained mutant restores endosomal trafficking not fully explained","Stabilization mechanism at the molecular level undefined"]},{"year":2019,"claim":"Established opposing receptor-specific regulatory logic: UNC93B1 actively terminates TLR7 via syntenin-1 sorting, while it must release TLR9 in endosomes to permit signaling.","evidence":"Co-IP, exosome fractionation, phosphorylation analysis and autoimmunity knock-in mice for TLR7; pH/compartment Co-IP, affinity mutations and engineered tethers for TLR9","pmids":["31546246","31546247"],"confidence":"High","gaps":["Kinase phosphorylating UNC93B1 not identified","Trigger for TLR9 release within endosomes not defined"]},{"year":2021,"claim":"Provided atomic-resolution interaction interfaces and revealed UNC93B1's MFS-transporter-like architecture, and uncovered its negative regulation of cGAS-STING.","evidence":"Cryo-EM of TLR3- and TLR7-UNC93B1 complexes; Co-IP and KO functional assays showing STING degradation; CNS expression and let-7b neurodegeneration studies","pmids":["33432245","33837956","34589086"],"confidence":"High","gaps":["STING regulation findings were Medium-confidence single-lab studies","Functional consequence of MFS-like fold (potential transport activity) untested"]},{"year":2022,"claim":"Mechanistically detailed UNC93B1 control over STIM1 conformation and added a post-translational requirement for TLR9 signaling.","evidence":"Cysteine crosslinking, Co-IP and calcium/Orai1 assays for STIM1 helix zipping; N-glycosylation mutagenesis (N272Q) with MyD88-recruitment assays; STING-degradation confirmation","pmids":["35065962","35874766","35577759"],"confidence":"High","gaps":["Why Asn272 glycosylation specifically gates MyD88 recruitment unclear","Integration of calcium and TLR functions in one protein not unified"]},{"year":2024,"claim":"Comprehensively mapped UNC93B1 regulatory regions and connected a spectrum of human variants to TLR-subtype-specific autoimmune disease.","evidence":"Scanning alanine mutagenesis with CRISPR knock-in mice; multiple patient-derived variants (E92G, R336L, I317M, G325C, L330R, R466S, R525P, T93I, R336C, V117L, T314A) with TLR-specific signaling, Co-IP and lupus-like mouse models","pmids":["38207055","38869500","38780621","38831104"],"confidence":"High","gaps":["Distinct molecular mechanisms among variants (instability vs enhanced TLR binding) not unified into a single model","Therapeutic targeting of variant-specific hyperactivation untested"]},{"year":null,"claim":"Whether UNC93B1's MFS-transporter-like fold confers an actual transport activity, the identity of the kinase phosphorylating UNC93B1 for syntenin-1 recruitment, and the trigger for endosomal TLR release remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No demonstrated substrate or transport function despite MFS-like architecture","UNC93B1 kinase unidentified","PANK4 as a negative-regulatory partner rests only on a preprint single Co-IP"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,13]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,1,5]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,14,15]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[1,2,6,13]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[2,11,15]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[18,19]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[8,21]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,1,2,6]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[2,6,8]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[6,14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[23,24,25,26]}],"complexes":[],"partners":["TLR3","TLR7","TLR9","TLR8","TLR5","STIM1","STING1","SDCBP"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H1C4","full_name":"Protein unc-93 homolog B1","aliases":[],"length_aa":597,"mass_kda":66.6,"function":"Plays an important role in innate and adaptive immunity by regulating nucleotide-sensing Toll-like receptor (TLR) signaling. 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UNC93B1 mutations in humans result in impaired cellular IFN-α/β and IFN-λ antiviral responses, establishing UNC93B1 as essential for TLR3/7/9-dependent antiviral signaling in vivo.\",\n      \"method\": \"Human genetic study; functional assays in patient cells (interferon response measurements)\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patient loss-of-function mutations with functional cellular readout, replicated across multiple independent studies\",\n      \"pmids\": [\"16973841\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"A missense mutation (H412R) in Unc93b1 ('3d' mutation) abolishes signaling through intracellular TLR3, TLR7, and TLR9, and also impairs cross-presentation and MHC class II presentation of exogenous antigen; UNC93B1 was identified as a 12-transmembrane-spanning ER-resident protein.\",\n      \"method\": \"ENU mutagenesis screen; positional cloning; functional TLR signaling assays; antigen presentation assays in dendritic cells\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — positional cloning with functional validation, replicated across multiple subsequent studies\",\n      \"pmids\": [\"16415873\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"UNC93B1 physically interacts with TLR7 and TLR9 in the ER and delivers them to endolysosomes; the H412R mutation prevents TLR binding and blocks ER exit of TLR7 and TLR9, while wild-type UNC93B1 rescues trafficking and signaling defects in 3d dendritic cells.\",\n      \"method\": \"Co-immunoprecipitation; subcellular fractionation; live-cell imaging; genetic complementation in 3d dendritic cells\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, subcellular localization, functional rescue, replicated across multiple labs\",\n      \"pmids\": [\"18305481\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"UNC93B1 residue D34 represses TLR7-mediated responses while favoring TLR9; D34A mutation increases Unc93B1 association with TLR7 and ligand-induced TLR7 trafficking while decreasing TLR9 association and trafficking, biasing nucleic acid sensing toward DNA-sensing in dendritic cells.\",\n      \"method\": \"Complementation cloning; co-immunoprecipitation; endolysosomal trafficking assays; TLR signaling assays with TLR-specific ligands\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mutagenesis combined with Co-IP, trafficking assays, and signaling readouts; replicated in subsequent studies\",\n      \"pmids\": [\"19451267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"UNC93B1 interacts directly with TLR11 in the ER and is required for TLR11-dependent IL-12 secretion and dendritic cell activation in response to Toxoplasma gondii profilin, demonstrating that UNC93B1 interaction and intracellular localization are not unique to nucleic acid-sensing TLRs.\",\n      \"method\": \"Co-immunoprecipitation; subcellular localization; IL-12 secretion assays; in vivo infection model with UNC93B1-deficient mice\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct Co-IP with functional in vitro and in vivo readouts\",\n      \"pmids\": [\"21097503\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"TLR9 competes with TLR7 for UNC93B1-dependent trafficking and predominates; a D34A mutation in UNC93B1 reverses this balance toward TLR7, causing TLR7-dependent systemic lethal inflammation in mice driven by CD4+ T cell Th1/Th17 differentiation and B cell activity.\",\n      \"method\": \"Knock-in mouse model (D34A); TLR competition assays; flow cytometry; B cell depletion experiments\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic model with mechanistic dissection using cell depletion, replicated concept from earlier biochemical studies\",\n      \"pmids\": [\"21683627\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"UNC93B1 enters the secretory pathway and directly controls packaging of TLRs into COPII vesicles budding from the ER; it remains associated with TLRs through post-Golgi sorting. TLR9 requires UNC93B1-mediated AP-2 recruitment for endolysosomal delivery, while TLR7, TLR11, TLR12, and TLR13 use alternative trafficking pathways.\",\n      \"method\": \"COPII vesicle budding assays; co-immunoprecipitation; AP complex interaction assays; subcellular trafficking analysis\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro COPII budding reconstitution combined with multiple trafficking assays and receptor-specific mechanistic dissection\",\n      \"pmids\": [\"23426999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Acidic residues D812/E813 of TLR9 and D699/E704 of TLR3 in the juxtamembrane region are required for UNC93B1 binding; mutation of these residues prevents UNC93B1 interaction, impairs TLR trafficking from the ER, and abolishes TLR signaling.\",\n      \"method\": \"Site-directed mutagenesis of TLR juxtamembrane residues; co-immunoprecipitation; subcellular localization; signaling assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis with multiple functional readouts (binding, trafficking, signaling), single lab\",\n      \"pmids\": [\"23585677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"UNC93B1 is essential for plasma membrane localization and signaling of TLR5 (a flagellin receptor); TLR5 physically interacts with UNC93B1, and cells from 3d or UNC93B1-deficient mice lack TLR5 at the plasma membrane and fail to produce cytokines upon flagellin stimulation.\",\n      \"method\": \"Co-immunoprecipitation; cell surface localization assays; cytokine secretion and costimulatory molecule upregulation in 3d and UNC93B1-KO cells\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP plus localization plus functional readout in genetic mouse models, confirmed with multiple cell types\",\n      \"pmids\": [\"24778236\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"A C-terminal tyrosine-based sorting motif (YxxΦ) in UNC93B1 differentially regulates TLR7, TLR8, and TLR9 activity toward nucleic acid ligands in human B cells and monocytes; destruction of YxxΦ abolishes these TLR responses. YxxΦ controls UNC93B1 subcellular localization via both AP1- and AP2-dependent pathways, but loss of AP function does not recapitulate altered TLR responses, indicating AP-independent functions.\",\n      \"method\": \"Site-directed mutagenesis of UNC93B1 YxxΦ motif; TLR signaling assays in human primary cells; AP complex knockdown; subcellular localization imaging\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — mutagenesis with functional signaling readouts in primary human cells and multiple orthogonal approaches\",\n      \"pmids\": [\"25187660\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"UNC93B1 physically associates with human TLR8 and is required for TLR8-mediated signaling; TLR8 localizes to early endosomes and ER but not late endosomes or lysosomes, and the transmembrane domain and TIR domain of TLR8 are required for proper early endosomal targeting.\",\n      \"method\": \"Co-immunoprecipitation; subcellular localization (confocal microscopy with organelle markers); TLR8 signaling assays; truncation mutant analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with localization and signaling readout, single lab with multiple methods\",\n      \"pmids\": [\"22164301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"LRRC59, an ER membrane protein, associates with UNC93B1 upon ligand stimulation (in a TLR-independent manner requiring signals from ligand internalization) and promotes UNC93B1-mediated translocation of TLR3, TLR8, and TLR9 from the ER to endosomes.\",\n      \"method\": \"Co-immunoprecipitation (ligand-induced); siRNA knockdown of LRRC59; subcellular localization of endogenous TLR3; TLR signaling assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with KD functional readouts and localization, single lab\",\n      \"pmids\": [\"26466955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"UNC93B1 interacts with the ER calcium sensor STIM1, and this interaction is required for STIM1 oligomerization and activation; UNC93B1 deficiency impairs endosomal acidification, phagosomal maturation, antigen degradation, antigen export to the cytosol, and STIM1 function, resulting in compromised antigen cross-presentation. Expression of a constitutively active STIM1 mutant that does not bind UNC93B1 restores antigen degradation and cross-presentation in 3d-mutated DCs.\",\n      \"method\": \"Co-immunoprecipitation (UNC93B1-STIM1); constitutively active STIM1 mutant rescue; antigen cross-presentation assays; calcium flux measurements in 3d DCs\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP with functional rescue experiment using mutant STIM1, multiple cellular readouts, and genetic complementation\",\n      \"pmids\": [\"29158474\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"UNC93B1 deficiency causes near-complete loss of TLR3 and TLR7 proteins in primary dendritic cells and macrophages, demonstrating that UNC93B1 is critical for TLR protein stability upstream of trafficking; expression of an ER-retained UNC93B1 version is sufficient to stabilize TLRs and largely restore endosomal TLR trafficking and activity.\",\n      \"method\": \"Western blot of TLR protein levels in UNC93B1-KO vs WT primary cells; ER-retained UNC93B1 mutant rescue experiments; TLR signaling assays\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with quantitative protein level measurements, mechanistic rescue with ER-retained mutant, primary cell experiments\",\n      \"pmids\": [\"29768176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"UNC93B1 specifically limits TLR7 (but not TLR9) signaling by recruiting syntenin-1; UNC93B1 mutations that enhance TLR7 signaling disrupt syntenin-1 binding. UNC93B1 and TLR7 are detectable in exosomes, suggesting UNC93B1-syntenin-1 interaction facilitates sorting of TLR7 into intralumenal vesicles of multivesicular bodies to terminate signaling. Phosphorylation of UNC93B1 is required for syntenin-1 binding.\",\n      \"method\": \"Co-immunoprecipitation; exosome fractionation and Western blot; mutagenesis; phosphorylation analysis; TLR7-specific autoimmunity in knock-in mice\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP with biochemical and genetic evidence, exosome localization data, in vivo autoimmunity model, multiple orthogonal methods in one study\",\n      \"pmids\": [\"31546246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TLR9 (and TLR3) are released from UNC93B1 within endosomes, and this release is required for ligand binding and signal transduction; UNC93B1 mutations that increase TLR9 affinity or an artificial tether preventing release block TLR9 signaling. TLR7 does not dissociate from UNC93B1 in endosomes and is regulated by distinct mechanisms.\",\n      \"method\": \"Co-immunoprecipitation at different pH/compartments; tethered UNC93B1-TLR9 fusion constructs; affinity-increasing mutations; TLR signaling assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — biochemical dissection with engineered tether and affinity mutations, multiple orthogonal methods establishing mechanism\",\n      \"pmids\": [\"31546247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structures of human and mouse TLR3-UNC93B1 complexes and human TLR7-UNC93B1 complex reveal that UNC93B1 exhibits structural similarity to major facilitator superfamily transporters; both TLRs interact with the UNC93B1 N-terminal six-helix bundle through their transmembrane and luminal juxtamembrane regions; TLR3 and TLR7 complexes differ in their oligomerization state.\",\n      \"method\": \"Cryo-electron microscopy structural determination\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — atomic-resolution cryo-EM structures of two distinct TLR-UNC93B1 complexes from human and mouse, establishing direct interaction interface\",\n      \"pmids\": [\"33432245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"N-glycosylation of UNC93B1 at Asn272 (but not Asn251) is required for TLR9 signaling; the N272Q mutation selectively impairs MyD88 recruitment to TLR9 and downstream signaling without affecting TLR7 signaling, UNC93B1 expression, or TLR9 localization. The two N-glycosylation sites (Asn251 and Asn272) can be glycosylated independently.\",\n      \"method\": \"Site-directed mutagenesis (N251Q, N272Q); TLR9 signaling assays; co-immunoprecipitation of MyD88-TLR9; subcellular localization; TLR7 signaling comparison\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — site-directed mutagenesis with multiple functional readouts (signaling, MyD88 recruitment, localization), single lab\",\n      \"pmids\": [\"35874766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"UNC93B1 attenuates cGAS-STING signaling by directly interacting with STING and delivering it to lysosomes for autophagy-dependent degradation; UNC93B1 knockout enhances STING-dependent IFN-β production and reduces STING protein degradation. This function depends on UNC93B1 trafficking capability.\",\n      \"method\": \"Co-immunoprecipitation (UNC93B1-STING); UNC93B1 overexpression and knockout; lysosome inhibitor rescue; IFN-β promoter assays; IRF3 nuclear translocation; HSV-1 infection in KO mice\",\n      \"journal\": \"Journal of medical virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with KO functional data and in vivo confirmation, single lab, partially replicated by independent study (PMID 33837956)\",\n      \"pmids\": [\"35577759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"UNC93B1 directly interacts with STING and promotes STING protein degradation; UNC93B1 deficiency blunts TLR3 signaling but augments innate immune responses to cytosolic DNA stimulation by causing STING accumulation, demonstrating a negative regulatory role on STING-mediated signaling.\",\n      \"method\": \"Co-immunoprecipitation (UNC93B1-STING); UNC93B1 knockdown/KO; cytosolic DNA stimulation assays; STING protein level measurement\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with KO functional readouts, single lab, corroborated by independent study (PMID 35577759)\",\n      \"pmids\": [\"33837956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"UNC93B1 interacts with STIM1 in the ER lumen near the transmembrane domain; UNC93B1 binding promotes zipping of transmembrane and proximal cytosolic helices within resting STIM1 dimers, priming them for translocation. UNC93B1 deficiency reduces store-operated Ca2+ entry, STIM1-Orai1 interactions, and targets STIM1 to lighter ER domains; UNC93B1 expression accelerates STIM1 recruitment to cortical ER domains.\",\n      \"method\": \"Co-immunoprecipitation; cysteine crosslinking in vivo; calcium flux measurements; STIM1-Orai1 Co-IP; subcellular fractionation; live-cell imaging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — cysteine crosslinking plus Co-IP plus functional calcium measurements, multiple orthogonal methods, directly extends prior finding (PMID 29158474)\",\n      \"pmids\": [\"35065962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"UNC93B1 promotes trafficking of differentially glycosylated TLR3 (but not other NA-sensing TLRs) to the plasma membrane in human epithelial cells; poly(I:C) up-regulates UNC93B1 transcription via TLR3 activation; UNC93B1 increases protein lifetime of TLR3 and TLR9 and augments signaling of all NA-sensing TLRs. Poly(I:C) pretreatment primes B cells to ssDNA activation via UNC93B1 up-regulation.\",\n      \"method\": \"siRNA knockdown; confocal microscopy for TLR3 localization; Western blot for protein stability; TLR signaling assays; UNC93B1 promoter analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple readouts (localization, stability, signaling) in single lab with siRNA and overexpression approaches\",\n      \"pmids\": [\"23166319\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In C. elegans, UNC-93 colocalizes with SUP-9 (a two-pore K+ channel) and SUP-10 within muscle cells, and genetic evidence suggests these three proteins form a multisubunit complex coordinating muscle contraction; UNC-93 defines a novel multigene family conserved in C. elegans, Drosophila, and humans.\",\n      \"method\": \"Genetic epistasis analysis; cloning of sup-9 and sup-10; colocalization by immunofluorescence in muscle cells\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — C. elegans ortholog colocalization; genetic evidence for complex but no direct biochemical reconstitution; not directly informative for mammalian UNC93B1 TLR function\",\n      \"pmids\": [\"14534247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"UNC93B1 variants E92G and R336L cause selective TLR7 hyperactivation; E92G causes UNC93B1 protein instability and reduced interaction with TLR7, leading to constitutive type I IFN signaling, while neither variant affects TLR3 or TLR9 responses, establishing UNC93B1 as a TLR subtype-specific regulator.\",\n      \"method\": \"Patient cell functional assays; mouse macrophage model with variants; co-immunoprecipitation (UNC93B1-TLR7); cytokine measurements; protein stability assays\",\n      \"journal\": \"Science immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — human patient variants with in vitro functional validation, Co-IP, and mouse model, multiple orthogonal readouts\",\n      \"pmids\": [\"38207055\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"UNC93B1 variants I317M, G325C cause gain of TLR7 and TLR8 activity in SLE patients; variants L330R, R466S, R525P cause gain of TLR8 activity in chilblain lupus patients. G325C, L330R, and R466S variants show enhanced interaction with TLR8 by Co-IP, while R525P does not, indicating different disease mechanisms for different mutations.\",\n      \"method\": \"In vitro TLR signaling assays; ex vivo patient cell assays; co-immunoprecipitation (UNC93B1 variants with TLR8)\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple patient-derived variants with TLR-specific functional assays and Co-IP, mechanistically distinct variants characterized\",\n      \"pmids\": [\"38869500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Systematic alanine scanning mutagenesis of all cytosolic and luminal UNC93B1 residues identified distinct positive and negative regulatory regions for TLR3, TLR7, and TLR9 responses; human variants UNC93B1-T93I and UNC93B1-R336C in identified negative regulatory regions enhance TLR7/8 responses and cause systemic autoimmune disease when introduced into mice.\",\n      \"method\": \"Scanning alanine mutagenesis screen; TLR signaling assays (TLR3, TLR7/8, TLR9); CRISPR knock-in mouse models; patient variant analysis\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic mutagenesis with functional signaling readouts plus in vivo knock-in validation, comprehensive mechanistic mapping\",\n      \"pmids\": [\"38780621\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"UNC93B1 variant V117L is associated with increased TLR7/8 (but not TLR3/TLR9) responses; variant T314A (proximal to TLR7 transmembrane domain) also causes exaggerated TLR7/8 responses; heterozygous mice expressing Unc93b1 V117L develop spontaneous lupus-like disease.\",\n      \"method\": \"Patient cell functional assays; THP-1 cell TLR stimulation assays; heterozygous knock-in mouse model; cytokine and IFN measurements\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patient variants validated in cell lines and in vivo mouse model with receptor-specific functional readouts\",\n      \"pmids\": [\"38831104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"UNC93B1 is expressed in multiple CNS cell types (microglia, astrocytes, oligodendrocytes, neurons) and is required for microglial activation and neuronal injury induced by extracellular let-7b (a TLR7 activator); intrathecal let-7b causes neurodegeneration in wild-type but not UNC93B1-deficient mice.\",\n      \"method\": \"PCR, immunocytochemistry, flow cytometry for expression; TNF ELISA in UNC93B1-deficient microglia; neuronal injury assays in vitro; intrathecal injection in vivo; neurodegeneration assessment\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple cell type expression confirmed, functional KO readout in both in vitro and in vivo models, single lab\",\n      \"pmids\": [\"34589086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PANK4 interacts with UNC93B1 to suppress TLR7 and TLR9-mediated cytokine responses, acting as a negative regulator of nucleic acid-sensing innate immune pathways.\",\n      \"method\": \"Co-immunoprecipitation (PANK4-UNC93B1); TLR7/9 signaling assays with PANK4 loss-of-function\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single Co-IP with functional readout, not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"UNC93B1 is a 12-transmembrane ER-resident chaperone protein that physically associates with nucleic acid-sensing TLRs (TLR3, TLR7, TLR8, TLR9, TLR11, TLR12, TLR13) and TLR5 in the ER, stabilizes them, loads them into COPII vesicles for ER exit, and differentially traffics them to endolysosomes (or the plasma membrane for TLR5) via receptor-specific mechanisms including AP-2 recruitment for TLR9; it also controls the balance of TLR7 vs. TLR9 signaling through preferential binding regulated by residue D34, terminates TLR7 signaling by recruiting syntenin-1 (in a phosphorylation-dependent manner) to sort TLR7 into multivesicular body intralumenal vesicles, enforces compartmentalized TLR9 activation by releasing TLR9 (but not TLR7) only within endosomes, negatively regulates cGAS-STING signaling by interacting with STING and promoting its lysosomal degradation, and interacts with STIM1 in the ER to prime it for store-operated calcium entry, thereby linking TLR trafficking to calcium signaling and antigen cross-presentation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"UNC93B1 is a polytopic ER membrane protein that serves as the master chaperone and trafficking regulator for nucleic-acid-sensing and select other Toll-like receptors, and is essential for TLR3/7/9-dependent type I/III interferon antiviral immunity in humans [#0, #1]. It physically binds nascent TLRs in the ER—engaging acidic juxtamembrane residues of TLR9 and TLR3 and contacting the transmembrane and luminal juxtamembrane regions of TLR3 and TLR7 through its N-terminal six-helix bundle, with an overall fold resembling major facilitator superfamily transporters [#7, #16]—and stabilizes TLR protein, such that its loss causes near-complete depletion of TLR3 and TLR7 even before trafficking [#13]. UNC93B1 then escorts these receptors out of the ER by packaging them into COPII vesicles and directing them through the secretory pathway to distinct destinations: endolysosomes for TLR7/9/11/13 and the plasma membrane for the flagellin receptor TLR5, using receptor-specific routes including AP-2 recruitment for TLR9 and a C-terminal Yxxϕ sorting motif [#6, #8, #9]. Beyond delivery, UNC93B1 sets the balance and intensity of TLR signaling: residue D34 represses TLR7 while favoring TLR9, and disruption of this balance toward TLR7 drives systemic autoimmune inflammation in mice [#3, #5]. It terminates TLR7 signaling by recruiting syntenin-1 in a phosphorylation-dependent manner to sort TLR7 into multivesicular-body intralumenal vesicles, whereas TLR9 (and TLR3) must be released from UNC93B1 within endosomes to bind ligand and signal, enforcing receptor-specific, compartmentalized activation [#14, #15]. A spectrum of human UNC93B1 variants that selectively enhance TLR7 and/or TLR8 activity cause systemic lupus erythematosus and chilblain lupus, establishing UNC93B1 as a TLR-subtype-specific gatekeeper of autoimmunity [#23, #24, #25, #26]. UNC93B1 additionally interacts with the ER calcium sensor STIM1 to prime its activation and support store-operated calcium entry and antigen cross-presentation [#12, #20], and negatively regulates cGAS-STING signaling by delivering STING for lysosomal degradation [#18, #19].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that UNC93B1 is non-redundantly required for intracellular TLR-driven antiviral immunity, converting a then-unknown gene into a central node of innate nucleic-acid sensing.\",\n      \"evidence\": \"Human loss-of-function mutations with interferon-response assays in patient cells, and an ENU 3d (H412R) mouse mutation abolishing TLR3/7/9 signaling and antigen presentation\",\n      \"pmids\": [\"16973841\", \"16415873\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the molecular mechanism by which UNC93B1 acts on TLRs\", \"Localization as a 12-TM ER protein noted but interaction partners not yet mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Resolved how UNC93B1 acts mechanistically by showing it physically binds TLR7/9 in the ER and is required for their ER exit and endolysosomal delivery.\",\n      \"evidence\": \"Reciprocal Co-IP, subcellular fractionation, live imaging, and genetic complementation of 3d dendritic cells\",\n      \"pmids\": [\"18305481\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the TLR binding interface\", \"Did not explain receptor-specific differences in trafficking\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed UNC93B1 not only traffics but biases TLR usage, identifying residue D34 as a switch repressing TLR7 in favor of TLR9.\",\n      \"evidence\": \"Complementation cloning, Co-IP, endolysosomal trafficking and TLR-ligand signaling assays of D34A mutant\",\n      \"pmids\": [\"19451267\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological consequence of altered balance not yet shown in vivo\", \"Structural basis of D34-mediated selectivity unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrated the in vivo pathological stakes of the TLR7/9 balance and broadened the client repertoire beyond nucleic-acid sensors.\",\n      \"evidence\": \"D34A knock-in mice with cell-depletion dissection showing TLR7-driven lethal inflammation; Co-IP and infection studies establishing TLR11 and TLR8 as UNC93B1-dependent\",\n      \"pmids\": [\"21683627\", \"21097503\", \"22164301\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of TLR competition for UNC93B1 not defined biochemically\", \"TLR8 finding was Medium-confidence single-lab\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined the secretory-pathway logic of UNC93B1 action: COPII packaging of TLRs and receptor-specific sorting machinery, plus the TLR binding determinants.\",\n      \"evidence\": \"In vitro COPII budding reconstitution, AP-complex interaction assays, and site-directed mutagenesis of TLR9/TLR3 juxtamembrane acidic residues\",\n      \"pmids\": [\"23426999\", \"23585677\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Alternative trafficking pathways for TLR7/11/12/13 not molecularly defined\", \"How UNC93B1 selects AP-2 for TLR9 specifically unresolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Extended UNC93B1's chaperone role to a cell-surface TLR and dissected its own sorting-motif requirements.\",\n      \"evidence\": \"Co-IP and surface-localization assays for TLR5 in 3d/KO cells; Yxxϕ motif mutagenesis with AP1/AP2 knockdown in human primary cells\",\n      \"pmids\": [\"24778236\", \"25187660\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"AP-independent functions of Yxxϕ implied but unidentified\", \"How UNC93B1 distinguishes plasma-membrane vs endosomal destinations unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified an ER co-factor coupling ligand sensing to TLR translocation.\",\n      \"evidence\": \"Ligand-induced Co-IP, LRRC59 knockdown, and TLR3 localization/signaling assays\",\n      \"pmids\": [\"26466955\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab finding without reciprocal in vivo validation\", \"Mechanism linking ligand internalization to LRRC59-UNC93B1 association unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Revealed a TLR-independent function: UNC93B1 partners with STIM1 to enable calcium signaling and antigen cross-presentation.\",\n      \"evidence\": \"Co-IP plus constitutively active STIM1 rescue, calcium flux and cross-presentation assays in 3d DCs\",\n      \"pmids\": [\"29158474\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of STIM1 priming not yet resolved at this stage\", \"Relationship between calcium role and TLR trafficking role unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Distinguished UNC93B1's stabilization function from its trafficking function, showing protein stability is the upstream requirement.\",\n      \"evidence\": \"Quantitative TLR protein measurement in KO vs WT primary cells and ER-retained UNC93B1 mutant rescue\",\n      \"pmids\": [\"29768176\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How an ER-retained mutant restores endosomal trafficking not fully explained\", \"Stabilization mechanism at the molecular level undefined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established opposing receptor-specific regulatory logic: UNC93B1 actively terminates TLR7 via syntenin-1 sorting, while it must release TLR9 in endosomes to permit signaling.\",\n      \"evidence\": \"Co-IP, exosome fractionation, phosphorylation analysis and autoimmunity knock-in mice for TLR7; pH/compartment Co-IP, affinity mutations and engineered tethers for TLR9\",\n      \"pmids\": [\"31546246\", \"31546247\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase phosphorylating UNC93B1 not identified\", \"Trigger for TLR9 release within endosomes not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Provided atomic-resolution interaction interfaces and revealed UNC93B1's MFS-transporter-like architecture, and uncovered its negative regulation of cGAS-STING.\",\n      \"evidence\": \"Cryo-EM of TLR3- and TLR7-UNC93B1 complexes; Co-IP and KO functional assays showing STING degradation; CNS expression and let-7b neurodegeneration studies\",\n      \"pmids\": [\"33432245\", \"33837956\", \"34589086\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"STING regulation findings were Medium-confidence single-lab studies\", \"Functional consequence of MFS-like fold (potential transport activity) untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Mechanistically detailed UNC93B1 control over STIM1 conformation and added a post-translational requirement for TLR9 signaling.\",\n      \"evidence\": \"Cysteine crosslinking, Co-IP and calcium/Orai1 assays for STIM1 helix zipping; N-glycosylation mutagenesis (N272Q) with MyD88-recruitment assays; STING-degradation confirmation\",\n      \"pmids\": [\"35065962\", \"35874766\", \"35577759\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why Asn272 glycosylation specifically gates MyD88 recruitment unclear\", \"Integration of calcium and TLR functions in one protein not unified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Comprehensively mapped UNC93B1 regulatory regions and connected a spectrum of human variants to TLR-subtype-specific autoimmune disease.\",\n      \"evidence\": \"Scanning alanine mutagenesis with CRISPR knock-in mice; multiple patient-derived variants (E92G, R336L, I317M, G325C, L330R, R466S, R525P, T93I, R336C, V117L, T314A) with TLR-specific signaling, Co-IP and lupus-like mouse models\",\n      \"pmids\": [\"38207055\", \"38869500\", \"38780621\", \"38831104\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Distinct molecular mechanisms among variants (instability vs enhanced TLR binding) not unified into a single model\", \"Therapeutic targeting of variant-specific hyperactivation untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether UNC93B1's MFS-transporter-like fold confers an actual transport activity, the identity of the kinase phosphorylating UNC93B1 for syntenin-1 recruitment, and the trigger for endosomal TLR release remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No demonstrated substrate or transport function despite MFS-like architecture\", \"UNC93B1 kinase unidentified\", \"PANK4 as a negative-regulatory partner rests only on a preprint single Co-IP\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 13]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 14, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [1, 2, 6, 13]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [2, 11, 15]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [18, 19]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [8, 21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 1, 2, 6]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 6, 8]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [6, 14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [23, 24, 25, 26]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TLR3\", \"TLR7\", \"TLR9\", \"TLR8\", \"TLR5\", \"STIM1\", \"STING1\", \"SDCBP\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}