{"gene":"TLR9","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2005,"finding":"DNA-containing immune complexes from SLE serum activate plasmacytoid DCs via cooperative interaction between CD32 (FcγRIIa) and TLR9: CD32 delivers SLE-ICs to intracellular lysosomes containing TLR9, where signaling is initiated. SLE-ICs transiently colocalized to a subcellular compartment containing both CD32 and TLR9, and only CD32+ PDCs internalized and responded to SLE-ICs.","method":"Subcellular colocalization imaging, functional cell stimulation with CD32+ vs CD32- PDCs, cytokine/chemokine readout","journal":"The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal functional and colocalization data in primary cells, single lab, two complementary methods","pmids":["15668740"],"is_preprint":false},{"year":2004,"finding":"TLR9 is expressed in the endoplasmic reticulum at rest and translocates to a tubular lysosomal compartment upon CpG-DNA stimulation, where it binds DNA and initiates signaling. In contrast, TLR4 is expressed on the plasma membrane.","method":"Fluorescent protein-tagged TLR9 and TLR4 subcellular localization comparison; fluorescently tagged CpG-DNA trafficking in human pDCs","journal":"Journal of endotoxin research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live-cell imaging with functional context, single lab, direct localization experiment","pmids":["15588423"],"is_preprint":false},{"year":2008,"finding":"Protein kinase D1 (PKD1) is activated by CpG-B DNA through a pathway dependent on endosomal pH, TLR9, MyD88, and IRAK1 in macrophages. Upon CpG-B stimulation, PKD1 interacts with the TLR9/MyD88/IRAK/TRAF6 signaling complex, and knockdown of PKD1 impairs NF-κB and MAPK activation and downstream cytokine expression.","method":"Co-immunoprecipitation, siRNA knockdown, kinase activation assays in macrophages","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional knockdown, single lab, two complementary methods","pmids":["18641342"],"is_preprint":false},{"year":2005,"finding":"TLR9 is NOT required for CpG-DNA-induced Akt activation; instead, DNA-PKcs directly phosphorylates and activates Akt in response to CpG-DNA and associates with Akt upon stimulation in bone marrow-derived macrophages, triggering transient nuclear translocation of Akt.","method":"In vitro kinase assay with purified DNA-PK and recombinant Akt; bone marrow-derived macrophages from TLR9-/- and DNA-PKcs-/- mice; Co-IP of DNA-PKcs with Akt","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified proteins plus genetic knockout macrophages plus Co-IP, multiple orthogonal methods in single rigorous study","pmids":["15678105"],"is_preprint":false},{"year":2012,"finding":"HRS (hepatocyte growth factor-regulated tyrosine kinase substrate) is required for ubiquitin-dependent TLR9 targeting to the endolysosome, identified via genome-wide RNAi screening; cofactors including ubiquitin-protein ligase activities, sphingolipid metabolism, chromatin modifications, and ancient stress response pathways modulate TLR9 endosomal signaling.","method":"Genome-wide RNAi screen; integrative systems analysis; functional validation of HRS knockdown on TLR9 endolysosomal trafficking","journal":"Cell host & microbe","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide screen with functional validation of TLR9 trafficking, single study, multiple orthogonal analyses","pmids":["22423970"],"is_preprint":false},{"year":2012,"finding":"TLR9 requires proteolytic cleavage for activation in all primary APC types tested (macrophages, dendritic cells, B cells), but the cathepsin requirement and rate of cleavage differ by cell type: macrophages require cathepsins L and S jointly, while B cells require cathepsin L alone. TLR9 trafficking and processing kinetics also differ between cell types, with B cells showing faster processing and near-exclusive endolysosomal localization at rest. UNC93B1 expression level is tightly correlated with TLR9-GFP cleavage.","method":"Transgenic TLR9-GFP mice; proteolytic processing assays; cathepsin inhibitors; UNC93B1 3d mutant mice; bone marrow-derived macrophages, DCs, and B cells","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — transgenic reporter mouse plus genetic mutants plus pharmacological inhibitors, multiple cell types, rigorous mechanistic dissection","pmids":["23241879"],"is_preprint":false},{"year":2015,"finding":"DNase II digestion of DNA in endolysosomes is required for TLR9 activation by CpG-A (but not CpG-B). DNase II cleaves CpG-A from 20-mer to 11–12-mer fragments, and these 3′ 11-mer fragments can activate DNase II-deficient DCs. CpG-A shows higher colocalization with LAMP-2+ lysosomes than CpG-B, and DNase II localizes to LAMP-2+ lysosomes upon CpG-A stimulation. DNase II is also required for TLR9 activation by bacterial genomic DNA.","method":"DNase II-deficient dendritic cells; enzymatically inactive DNase II mutants; synthetic DNA fragment rescue experiments; subcellular colocalization microscopy","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — genetic knockout plus enzymatic mutant rescue plus synthetic fragment validation plus colocalization, multiple orthogonal methods in single study","pmids":["25600358"],"is_preprint":false},{"year":2017,"finding":"BAD-LAMP (LAMP5) controls TLR9 trafficking to LAMP1+ late endosomes in human plasmacytoid dendritic cells, promoting NF-κB activation and TNF production. An inducible VAMP3+/LAMP2+/LAMP1- endolysosomal compartment exists in pDCs from which TLR9 activation triggers type I IFN expression. BAD-LAMP silencing enhances TLR9 retention in this IFN-producing compartment, whereas sustained BAD-LAMP expression promotes TLR9 sorting to late endosomes and limits type I IFN production.","method":"siRNA silencing of BAD-LAMP in primary human pDCs; subcellular compartment characterization by multi-marker imaging; cytokine output measurement","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional silencing plus compartment-resolved trafficking analysis in primary human cells, clear mechanistic dissection of IFN vs NF-κB outputs","pmids":["29030552"],"is_preprint":false},{"year":2016,"finding":"Dectin-1 controls TLR9 trafficking to phagosomes containing β-1,3 glucan. β-1,3 glucan bead recognition by Dectin-1 induces dynamic redistribution and accumulation of cleaved TLR9 to phagosomes. This trafficking requires phagosomal acidification and Dectin-1-mediated spleen tyrosine kinase (Syk) activation. Dectin-1 also regulates TLR9-dependent gene expression.","method":"Live-cell imaging; pharmacological inhibition of phagosomal acidification; Syk inhibitors; Dectin-1-dependent trafficking assays with fungal pathogens","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct trafficking imaging plus functional inhibition, single lab, two complementary methods","pmids":["26829985"],"is_preprint":false},{"year":2019,"finding":"The tetraspanin CD82 associates with TLR9 in the endoplasmic reticulum and post-ER compartments of macrophages, is essential for TLR9-dependent myddosome formation in response to CpG stimulation, and modulates TLR9-dependent NF-κB nuclear translocation and inflammatory cytokine production.","method":"Co-immunoprecipitation; myddosome formation assay; NF-κB nuclear translocation assay; CD82-deficient macrophages","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional knockout plus downstream signaling readout, single lab, multiple orthogonal methods","pmids":["31408613"],"is_preprint":false},{"year":2014,"finding":"Bruton's tyrosine kinase (BTK) is required for human dendritic cell activation via TLR9: CpG/TLR9-induced upregulation of activation markers (CD86, CD83, CD80, HLA-DR) and cytokine production (IL-6, IL-12, TNF-α, IL-10) are completely impaired in XLA patients lacking functional BTK, and BTK mediates TLR9-dependent STAT1/3 upregulation. BTK inhibition with ibrutinib phenocopies XLA in healthy DCs.","method":"Human DCs from XLA patients; ibrutinib pharmacological inhibition; cytokine ELISA; flow cytometry for activation markers; STAT1/3 western blotting","journal":"The Journal of allergy and clinical immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic patient cells plus pharmacological inhibition, consistent phenotype across two orthogonal loss-of-function approaches","pmids":["24612681"],"is_preprint":false},{"year":2014,"finding":"RNA:DNA hybrids are a novel molecular pattern specifically sensed by TLR9. Hybrid-induced pro-inflammatory cytokine and type I IFN production in dendritic cells requires MyD88-dependent signaling, demonstrating TLR9 as the sensor.","method":"Cytokine induction in dendritic cells with viral-derived RNA:DNA hybrids; MyD88-deficient cells; TLR9-specific pathway analysis","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic MyD88 knockout plus ligand specificity testing, single lab, two complementary methods","pmids":["24514026"],"is_preprint":false},{"year":2024,"finding":"TLR9 undergoes a cycle of S-palmitoylation and depalmitoylation that controls its signaling. DHHC3 (protein acyltransferase) palmitoylates TLR9 at C258 and C265 in the Golgi and regulates TLR9 trafficking to endosomes. PPT1 (palmitoyl-protein thioesterase 1) removes S-palmitoylation from TLR9 in lysosomes and facilitates TLR9 release from UNC93B1. PPT1 deficiency or inhibition reduces TLR9-dependent IFNα and TNF production.","method":"Mass spectrometry for palmitoylation site identification; biochemical palmitoylation assays; DHHC3 and PPT1 genetic/chemical manipulation; TLR9 trafficking assays; murine lupus model (B6.Sle1yaa); ex vivo human pDC experiments","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — mass spectrometry site identification plus mutagenesis plus genetic knockout models plus pharmacological validation, multiple orthogonal methods in a single rigorous study","pmids":["38169466"],"is_preprint":false},{"year":2022,"finding":"TLR9 possesses distinct signaling modes: (1) a ligand- and MyD88-independent 'scaffold' protective function; (2) ligand-dependent but MyD88-independent regulatory signaling; and (3) MyD88-mediated proinflammatory signaling. The MyD88-independent regulatory roles are B cell-intrinsic and restrain differentiation into pathogenic age-associated B cells and plasmablasts in lupus.","method":"Two TLR9 point mutants generated in lupus-prone MRL/lpr mice (TLR9K51E lacking ligand binding; TLR9P915H lacking MyD88 binding); triple-mixed bone marrow chimeras; disease phenotyping","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — structure-function point mutants in vivo plus bone marrow chimeras, multiple genetic controls enabling functional dissection of distinct signaling modes","pmids":["36151396"],"is_preprint":false},{"year":2020,"finding":"TLR9 interacts with beclin 1 and this interaction increases during energy stress (glucose starvation, endurance exercise). TLR9 regulates assembly of the endolysosomal PI3KC3-C2 complex (containing beclin 1 and UVRAG) in skeletal muscle during exercise. TLR9-deficient mice fail to activate AMPK in skeletal muscle during exercise and show reduced GLUT4 plasma membrane localization, but autophagy is not impaired. TLR9 functions cell-autonomously in ex vivo contraction-induced AMPK activation and glucose uptake.","method":"TLR9-knockout mice; Co-IP of TLR9 with beclin 1; ex vivo skeletal muscle contraction; AMPK activation assays; GLUT4 localization; beclin 1 and UVRAG conditional knockouts; BCL2 mutant mice","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — Co-IP plus multiple genetic knockouts plus ex vivo contraction model, multiple orthogonal methods establishing non-immune function in skeletal muscle","pmids":["32051584"],"is_preprint":false},{"year":2019,"finding":"During inflammatory preconditioning in neutrophils, TLR9 undergoes membrane translocation from the cytosol to the plasma membrane, where it binds to Cav-1. This TLR9-Cav-1 interaction enables TLR9 to facilitate MyD88-mediated TRAF3 and IRF3 signal transduction. Depletion of either TLR9 or Cav-1 eliminates the protective effect.","method":"Co-IP; fluorescence microscopy; FRET; flow cytometry; TLR9 and Cav-1 knockout models; sepsis models in vitro and in vivo","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, FRET, and genetic knockouts, single lab, multiple orthogonal methods","pmids":["31534550"],"is_preprint":false},{"year":2019,"finding":"MAL (MyD88 adapter-like) adapter protein is engaged in TLR9-dependent IFNβ and TNFα expression in macrophages infected with HSV-1 or treated with CpG-C, acting through a non-canonical NF-κB pathway. ERK1/2 kinases are required for TLR9-dependent IFNβ and TNFα induction via this pathway.","method":"MAL-deficient macrophages; ERK1/2 inhibitor; HSV-1 infection and CpG-C stimulation; cytokine measurement; NF-κB pathway analysis","journal":"Journal of innate immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout plus pharmacological inhibition with consistent phenotype, single lab","pmids":["31851971"],"is_preprint":false},{"year":2018,"finding":"Dengue virus (an RNA virus) activates TLR9 in human dendritic cells by inducing release of mitochondrial DNA (mtDNA) into the cytosol. DENV infection disrupts TFAM-mtDNA association and activates mitochondrial permeability transition pores to release mtDNA; this activates TLR9 signaling leading to IFN production. TLR9 and cGAS comparably contribute to DENV-induced immune activation.","method":"TLR9 siRNA knockdown; TLR9-knockout bone marrow-derived DCs; side-by-side comparison with cGAS knockdown; mtDNA release assays; IFN measurement","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO plus siRNA knockdown plus mechanistic mtDNA release characterization, single lab","pmids":["29880709"],"is_preprint":false},{"year":2018,"finding":"Opa1 deficiency in muscle causes mitochondrial DNA release, which activates TLR9, leading to NF-κB activation and inflammation. Blockage or repression of TLR9 prevents NF-κB activation and inflammation in Opa1-deficient muscle cells, demonstrating TLR9 as the mediator upstream of NF-κB in this pathway. This process is cell-autonomous and independent of cell death.","method":"Muscle-specific Opa1 knockout mice; TLR9 knockdown/blockade; mtDNA depletion; NF-κB reporter assays; inflammatory gene expression","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout plus pharmacological blockade plus mtDNA depletion rescue, single lab, multiple orthogonal approaches","pmids":["29632021"],"is_preprint":false},{"year":2012,"finding":"TLR9-induced type I IFN mediates anti-inflammatory effects in experimental colitis. TLR9 or MyD88 deficiency abolishes the protective effect of probiotics and probiotic DNA. Neutralizing type I IFN antibodies abrogate TLR9-mediated anti-inflammatory effects, while recombinant IFN-β mimics them.","method":"TLR9-/- and MyD88-/- mice; anti-IFN neutralizing antibodies; recombinant IFN-β administration; DSS colitis model","journal":"Annals of the New York Academy of Sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout plus antibody neutralization plus cytokine rescue, single lab","pmids":["17057215"],"is_preprint":false},{"year":2016,"finding":"Hepatocyte-derived mitochondrial DNA (mtDNA) in microparticles activates TLR9 in NASH. NASH development in response to high-fat diet requires TLR9 on lysozyme-expressing cells. Removal of mtDNA-containing microparticles from plasma substantially reduces TLR9 activation capacity.","method":"TLR9 conditional knockout on lysozyme+ cells; microparticle depletion from plasma; TLR9 activation assays with NASH patient plasma; TLR9 antagonist treatment","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific genetic knockout plus ligand identification plus pharmacological antagonism plus human patient plasma validation, multiple orthogonal methods","pmids":["26808498"],"is_preprint":false},{"year":2012,"finding":"TLR9-dependent signaling in pneumococcal pneumonia induces KLF4 expression via a bacterial DNA-TLR9-MyD88-Src kinase pathway. KLF4 is recruited to the IL-10 promoter and is required for IL-10 expression during pneumococcal infection; siRNA knockdown of KLF4 blocks IL-10 induction.","method":"siRNA knockdown; chromatin immunoprecipitation; Western blot; ELISA; TLR9/MyD88 pathway inhibition; murine pneumonia model","journal":"The European respiratory journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus siRNA knockdown plus genetic pathway analysis, single lab, multiple orthogonal methods","pmids":["22653776"],"is_preprint":false},{"year":2024,"finding":"TLR9 signaling plays a role in memory formation: hippocampal CA1 neurons with learning-induced double-stranded DNA breaks and nuclear envelope ruptures activate TLR9 signaling and accumulate centrosomal DNA damage repair complexes. Neuron-specific TLR9 knockdown impairs memory while blunting fear conditioning-induced gene expression changes in CA1 neuron clusters. TLR9 has an essential role in centrosome function, DNA damage repair, ciliogenesis, and perineuronal net formation.","method":"Neuron-specific Tlr9 knockdown; contextual fear conditioning; transcriptomic analysis of CA1 clusters; immunofluorescence for centrosomal complexes and DNA damage markers","journal":"Nature","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-type-specific knockdown with behavioral and molecular readouts, single lab, novel non-immune function","pmids":["38538785"],"is_preprint":false},{"year":2024,"finding":"EBV suppresses TLR9 expression by downregulating m6A modification of TLR9 mRNA. EBV nuclear antigen 1 (EBNA1) promotes K48-linked ubiquitin-proteasome degradation of METTL3 (m6A writer), reducing TLR9 mRNA stability. YTHDF1 acts as an m6A reader of TLR9 mRNA, enhancing TLR9 expression by promoting translation in an m6A-dependent manner.","method":"m6A modification analysis; METTL3 knockdown; YTHDF1 functional studies; ubiquitin-proteasome pathway assays; METTL3 inhibitor (STM2457); B cell proliferation and immunoglobulin assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic and pharmacological perturbations with mechanistic m6A pathway dissection, single lab","pmids":["38537697"],"is_preprint":false},{"year":2023,"finding":"Oxidized mitochondrial DNA (ox-mtDNA) activates the TLR9-MyD88-inflammasome pathway in MDS hematopoietic stem and progenitor cells, demonstrated by increased lysosome formation, IRF7 translocation, ISG production, and TLR9 redistribution to the cell surface. TLR9 is necessary for ox-mtDNA-mediated NLRP3 inflammasome activation, shown by chemical inhibition and CRISPR knockout; TLR9 overexpression sensitizes cells to ox-mtDNA. TLR9 inhibition restores hematopoietic colony formation.","method":"CRISPR knockout; TLR9 lentiviral overexpression; TLR9 chemical inhibition; IRF7 translocation assay; inflammasome activation assays; colony formation assay","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO plus overexpression plus pharmacological inhibition, multiple orthogonal genetic/chemical approaches, single lab","pmids":["36835307"],"is_preprint":false},{"year":2011,"finding":"TLR9 and P2X7 are DAMP receptors upstream of NLRP3 inflammasome activation in acute pancreatitis. Genetic deletion of Tlr9 reduces pancreatic edema, inflammation, and pro-IL-1β expression. TLR9 is expressed in resident immune cells (predominantly macrophages) of the pancreas.","method":"Tlr9-/- mice; caerulein-induced pancreatitis; TLR9 antagonist IRS954; pro-IL-1β expression; histopathology","journal":"Gastroenterology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout plus pharmacological antagonism plus epistasis with inflammasome components, single lab","pmids":["21439959"],"is_preprint":false},{"year":2020,"finding":"B cell-intrinsic TLR9 expression is protective in lupus: TLR9 deficiency specifically in B cells exacerbates nephritis while extinguishing anti-nucleosome antibodies. B cell-specific TLR9 overexpression ameliorates nephritis. TLR9 deficiency in dendritic cells, plasmacytoid DCs, and neutrophils had no discernible effect on disease.","method":"Cell-type-specific TLR9 deletion and overexpression alleles in lupus-prone mice; nephritis histopathology; autoantibody measurement","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — complementary cell-type-specific deletion and overexpression in vivo with reciprocal phenotypes, rigorous genetic approach","pmids":["32191633"],"is_preprint":false},{"year":2015,"finding":"TLR9 ligation in pancreatic stellate cells (PSCs) induces fibrogenic transformation and secretion of CCL11, which promotes epithelial cell proliferation. TLR9 also has immune-suppressive effects in the pancreatic tumor microenvironment via induction of regulatory T cell recruitment and MDSC proliferation.","method":"TLR9 deletion mice; TLR9 ligation in isolated PSCs; CCL11 measurement; epithelial proliferation assays; immune cell characterization in tumor microenvironment","journal":"The Journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO plus cell-type-specific stimulation plus paracrine factor identification, single lab","pmids":["26481685"],"is_preprint":false},{"year":2013,"finding":"FCRL3 augments TLR9-mediated B cell proliferation, activation, and survival, but abrogates plasma cell differentiation and antibody production by halting BLIMP1 induction in an ERK-dependent fashion. FCRL3 ligation amplifies NF-κB and MAPK signaling cascades downstream of TLR9.","method":"FCRL3 ligation combined with CpG ODN (TLR9 agonist) in human B cells; NF-κB and MAPK signaling assays; BLIMP1 expression; ERK inhibition","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional stimulation experiments with signaling pathway readouts and specific inhibitor validation, single lab","pmids":["23857366"],"is_preprint":false},{"year":2022,"finding":"Pro-inflammatory PS-ASOs require TLR9 signaling, but their innate immune activity does not correlate with TLR9 binding affinity, suggesting alternative PS-ASO binding sites on TLR9 leading to full, partial, or no activation. Extracellular proteins HMGB1, S100A8, and HRG enhance innate immune responses of PS-ASOs, suggesting PS-ASO-protein complexes are sensed by TLR9. Reducing PS content of PS-ASOs decreases innate immune responses.","method":"TLR9 binding affinity measurements; co-incubation competition assays; recombinant protein enhancement assays; PS content modulation","journal":"Nucleic acids research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — binding and activity assays without direct structural or mutagenesis confirmation of alternative binding sites, single lab","pmids":["35848907"],"is_preprint":false}],"current_model":"TLR9 is an endosomal pattern recognition receptor that resides in the ER at rest and traffics to endolysosomes upon DNA ligand encounter; proteolytic cleavage (by cathepsins L and/or S, cell-type dependent) is universally required for activation; DNase II-generated DNA fragments are the direct TLR9 ligands in lysosomes; UNC93B1, BAD-LAMP, CD82, HRS, and DHHC3/PPT1-mediated palmitoylation cycles regulate TLR9 trafficking and compartment-specific signaling; upon activation TLR9 signals via MyD88–IRAK–TRAF6–PKD1 to activate NF-κB and MAPKs, and via IRF7 to induce type I IFNs, with MAL and BTK as additional required cofactors; ligand specificity is conferred by DNA methylation status (preferring unmethylated CpG), with RNA:DNA hybrids and oxidized/mitochondrial DNA also being recognized; CD32 can deliver extracellular DNA-immune complexes to TLR9-containing lysosomes; B cell-intrinsic TLR9 restrains pathogenic plasmablast differentiation in lupus through both MyD88-dependent proinflammatory and MyD88-independent regulatory scaffold functions; and beyond innate immunity, TLR9 interacts with beclin 1 to regulate AMPK activation and glucose uptake in skeletal muscle during exercise, and facilitates DNA damage repair at centrosomes in hippocampal neurons to support memory formation."},"narrative":{"mechanistic_narrative":"TLR9 is an intracellular nucleic-acid pattern-recognition receptor that surveys endolysosomal compartments for DNA and initiates innate immune signaling, but its biology extends to metabolic and neuronal functions beyond immunity [PMID:15588423, PMID:32051584, PMID:38538785]. At rest TLR9 resides in the endoplasmic reticulum and translocates to a tubular lysosomal compartment upon CpG-DNA encounter, where it binds ligand and signals [PMID:15588423]. Activation universally requires proteolytic cleavage in endolysosomes, with the cathepsin requirement differing by cell type—cathepsins L and S jointly in macrophages versus cathepsin L alone in B cells—and is tightly coupled to UNC93B1 expression [PMID:23241879]. Compartment-specific trafficking dictates signaling output: HRS mediates ubiquitin-dependent endolysosomal targeting [PMID:22423970], BAD-LAMP (LAMP5) sorts TLR9 between late-endosomal NF-κB-driving and VAMP3+ IFN-driving compartments [PMID:29030552], the tetraspanin CD82 chaperones TLR9 from the ER and enables myddosome formation [PMID:31408613], and a DHHC3/PPT1 S-palmitoylation cycle at C258/C265 controls Golgi-to-endosome trafficking and release from UNC93B1 [PMID:38169466]. Within lysosomes, DNase II processes CpG-A and bacterial genomic DNA into short fragments that constitute the activating ligands [PMID:25600358], and TLR9 recognizes diverse DNA species including RNA:DNA hybrids and oxidized/mitochondrial DNA [PMID:24514026, PMID:29880709, PMID:36835307]. Upon activation TLR9 assembles a MyD88–IRAK–TRAF6 complex that recruits PKD1 to drive NF-κB and MAPK activation [PMID:18641342], with MAL and BTK serving as additional required cofactors for cytokine and type I IFN induction [PMID:24612681, PMID:31851971]. Structure-function dissection in vivo reveals that TLR9 operates through three distinct modes—a ligand- and MyD88-independent scaffold function, ligand-dependent MyD88-independent regulatory signaling, and MyD88-dependent proinflammatory signaling—and B cell-intrinsic TLR9 is protective in lupus, restraining pathogenic plasmablast and age-associated B cell differentiation [PMID:36151396, PMID:32191633]. Independent of immunity, TLR9 interacts with beclin 1 to regulate PI3KC3-C2 assembly and AMPK-dependent glucose uptake in exercising skeletal muscle [PMID:32051584], and supports centrosomal DNA-damage repair in hippocampal neurons during memory formation [PMID:38538785].","teleology":[{"year":2004,"claim":"Establishing where TLR9 senses its ligand resolved why it detects intracellular rather than surface DNA, defining it as a compartmentalized receptor distinct from cell-surface TLRs.","evidence":"Fluorescent-tagged TLR9/TLR4 localization and CpG-DNA trafficking in human pDCs","pmids":["15588423"],"confidence":"Medium","gaps":["Did not define the molecular machinery driving ER-to-lysosome translocation","Did not address why endosomal localization is required for ligand discrimination"]},{"year":2005,"claim":"Identifying CD32 as a delivery receptor explained how extracellular DNA-immune complexes reach the intracellular TLR9 compartment, linking TLR9 to autoimmune activation.","evidence":"Subcellular colocalization and functional stimulation of CD32+ vs CD32- pDCs with SLE immune complexes","pmids":["15668740"],"confidence":"Medium","gaps":["Did not establish direct physical interaction between CD32 and TLR9","Did not define the handoff step from CD32 to TLR9 within the lysosome"]},{"year":2005,"claim":"Demonstrating that CpG-DNA can activate Akt independently of TLR9 via DNA-PKcs distinguished TLR9-dependent from TLR9-independent DNA sensing branches.","evidence":"In vitro kinase assay with purified DNA-PK, TLR9-/- and DNA-PKcs-/- macrophages, and Co-IP","pmids":["15678105"],"confidence":"High","gaps":["Did not address whether the two DNA-sensing branches cross-regulate","Scope limited to Akt activation"]},{"year":2008,"claim":"Placing PKD1 within the TLR9/MyD88/IRAK/TRAF6 complex identified a kinase node required to propagate signaling to NF-κB and MAPKs.","evidence":"Co-IP, siRNA knockdown, and kinase activation assays in macrophages","pmids":["18641342"],"confidence":"Medium","gaps":["Direct PKD1 substrates in the pathway not defined","Single cell type"]},{"year":2012,"claim":"Defining HRS-dependent ubiquitin-driven endolysosomal targeting and uncovering broad cofactor networks mapped the trafficking requirements for TLR9 signaling.","evidence":"Genome-wide RNAi screen with functional validation of HRS knockdown on TLR9 trafficking","pmids":["22423970"],"confidence":"Medium","gaps":["The ubiquitin ligase acting on TLR9 not identified","Most screen hits not individually mechanistically validated"]},{"year":2012,"claim":"Showing that proteolytic cleavage is universally required but cell-type-dependent in its cathepsin usage established processing as an obligatory activation step and explained cell-type differences in TLR9 responsiveness.","evidence":"Transgenic TLR9-GFP mice, cathepsin inhibitors, and UNC93B1 mutant mice across macrophages, DCs, and B cells","pmids":["23241879"],"confidence":"High","gaps":["Structural basis of the cleaved active receptor not resolved","Mechanism coupling UNC93B1 level to cleavage rate not defined"]},{"year":2014,"claim":"Identifying RNA:DNA hybrids as TLR9 ligands and demonstrating BTK as a required kinase broadened the ligand repertoire and the kinase requirements for TLR9-driven cytokine output.","evidence":"MyD88-deficient DCs with viral RNA:DNA hybrids; XLA patient DCs and ibrutinib inhibition","pmids":["24514026","24612681"],"confidence":"Medium","gaps":["Direct hybrid binding to TLR9 not structurally shown","BTK's precise position in the TLR9 signalosome not defined"]},{"year":2015,"claim":"Establishing that DNase II generates the short DNA fragments that actually activate TLR9 redefined the true ligand as a processed product rather than the input oligonucleotide.","evidence":"DNase II-deficient DCs, enzymatically inactive mutants, synthetic fragment rescue, and colocalization","pmids":["25600358"],"confidence":"High","gaps":["Why CpG-B bypasses the DNase II requirement not fully explained","Structural basis of fragment recognition not resolved"]},{"year":2016,"claim":"Linking Dectin-1-driven phagosomal trafficking and identifying mtDNA-microparticle ligands extended TLR9 sensing to fungal and metabolic-disease contexts.","evidence":"Live-cell imaging with Syk inhibitors (Dectin-1); cell-type-specific TLR9 knockout and microparticle depletion in NASH","pmids":["26829985","26808498"],"confidence":"Medium","gaps":["How phagosomal vs endosomal TLR9 pools differ functionally not defined","Mechanism of mtDNA escape into microparticles not detailed"]},{"year":2017,"claim":"Demonstrating that BAD-LAMP sorts TLR9 between distinct endolysosomal compartments explained how a single receptor produces either NF-κB/TNF or type I IFN outputs.","evidence":"siRNA silencing of BAD-LAMP in primary human pDCs with multi-marker compartment imaging and cytokine readout","pmids":["29030552"],"confidence":"High","gaps":["How compartment identity is mechanistically converted into distinct signaling not fully defined","Restricted to pDCs"]},{"year":2018,"claim":"Showing that mitochondrial DNA release (during RNA-virus infection or Opa1 loss) activates TLR9 established mtDNA as an endogenous danger ligand driving sterile and antiviral inflammation.","evidence":"TLR9 knockout/knockdown DCs with DENV; muscle-specific Opa1 knockout with TLR9 blockade and mtDNA depletion","pmids":["29880709","29632021"],"confidence":"Medium","gaps":["How cytosolic mtDNA reaches endolysosomal TLR9 not defined","Relative contribution of TLR9 vs cGAS context-dependent"]},{"year":2019,"claim":"Identifying CD82, MAL, and Cav-1 as context-specific cofactors refined the trafficking and adapter requirements for myddosome formation and IRF-directed signaling.","evidence":"Co-IP and knockout for CD82 (macrophages) and Cav-1 (neutrophils); MAL-deficient macrophages with ERK inhibition","pmids":["31408613","31851971","31534550"],"confidence":"Medium","gaps":["Whether these cofactors act in the same or distinct cell contexts not reconciled","Direct binding interfaces not mapped"]},{"year":2020,"claim":"Discovering the TLR9-beclin 1 interaction in skeletal muscle revealed a non-immune metabolic function controlling exercise-induced AMPK activation and glucose uptake.","evidence":"TLR9 knockout mice, Co-IP with beclin 1, ex vivo muscle contraction, and beclin1/UVRAG/BCL2 genetic models","pmids":["32051584"],"confidence":"High","gaps":["Whether this requires DNA ligand or signaling is unresolved","How TLR9 senses energy stress not defined"]},{"year":2020,"claim":"Cell-type-specific genetics showed B cell-intrinsic TLR9 is protective in lupus, overturning the assumption that TLR9 is uniformly pathogenic in autoimmunity.","evidence":"Cell-type-specific TLR9 deletion and overexpression in lupus-prone mice with nephritis and autoantibody phenotyping","pmids":["32191633"],"confidence":"High","gaps":["Molecular basis of the B cell-protective function not defined at this stage","How protective and pathogenic roles are balanced unclear"]},{"year":2022,"claim":"Structure-function point mutants dissected TLR9 into ligand-independent scaffold, ligand-dependent MyD88-independent regulatory, and MyD88-dependent proinflammatory modes, mechanistically explaining its protective B-cell function.","evidence":"TLR9K51E and TLR9P915H point mutants and triple-mixed bone marrow chimeras in MRL/lpr mice","pmids":["36151396"],"confidence":"High","gaps":["Molecular effectors of the MyD88-independent scaffold function not identified","How the three modes are partitioned across cell states unclear"]},{"year":2024,"claim":"Defining a DHHC3/PPT1 palmitoylation cycle and an m6A/METTL3/YTHDF1 expression circuit added post-translational and post-transcriptional layers controlling TLR9 trafficking and abundance.","evidence":"Mass spectrometry, palmitoylation-site mutagenesis, DHHC3/PPT1 manipulation, and lupus models; 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SLE-ICs transiently colocalized to a subcellular compartment containing both CD32 and TLR9, and only CD32+ PDCs internalized and responded to SLE-ICs.\",\n      \"method\": \"Subcellular colocalization imaging, functional cell stimulation with CD32+ vs CD32- PDCs, cytokine/chemokine readout\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal functional and colocalization data in primary cells, single lab, two complementary methods\",\n      \"pmids\": [\"15668740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TLR9 is expressed in the endoplasmic reticulum at rest and translocates to a tubular lysosomal compartment upon CpG-DNA stimulation, where it binds DNA and initiates signaling. In contrast, TLR4 is expressed on the plasma membrane.\",\n      \"method\": \"Fluorescent protein-tagged TLR9 and TLR4 subcellular localization comparison; fluorescently tagged CpG-DNA trafficking in human pDCs\",\n      \"journal\": \"Journal of endotoxin research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live-cell imaging with functional context, single lab, direct localization experiment\",\n      \"pmids\": [\"15588423\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Protein kinase D1 (PKD1) is activated by CpG-B DNA through a pathway dependent on endosomal pH, TLR9, MyD88, and IRAK1 in macrophages. Upon CpG-B stimulation, PKD1 interacts with the TLR9/MyD88/IRAK/TRAF6 signaling complex, and knockdown of PKD1 impairs NF-κB and MAPK activation and downstream cytokine expression.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, kinase activation assays in macrophages\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional knockdown, single lab, two complementary methods\",\n      \"pmids\": [\"18641342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"TLR9 is NOT required for CpG-DNA-induced Akt activation; instead, DNA-PKcs directly phosphorylates and activates Akt in response to CpG-DNA and associates with Akt upon stimulation in bone marrow-derived macrophages, triggering transient nuclear translocation of Akt.\",\n      \"method\": \"In vitro kinase assay with purified DNA-PK and recombinant Akt; bone marrow-derived macrophages from TLR9-/- and DNA-PKcs-/- mice; Co-IP of DNA-PKcs with Akt\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified proteins plus genetic knockout macrophages plus Co-IP, multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"15678105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HRS (hepatocyte growth factor-regulated tyrosine kinase substrate) is required for ubiquitin-dependent TLR9 targeting to the endolysosome, identified via genome-wide RNAi screening; cofactors including ubiquitin-protein ligase activities, sphingolipid metabolism, chromatin modifications, and ancient stress response pathways modulate TLR9 endosomal signaling.\",\n      \"method\": \"Genome-wide RNAi screen; integrative systems analysis; functional validation of HRS knockdown on TLR9 endolysosomal trafficking\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide screen with functional validation of TLR9 trafficking, single study, multiple orthogonal analyses\",\n      \"pmids\": [\"22423970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TLR9 requires proteolytic cleavage for activation in all primary APC types tested (macrophages, dendritic cells, B cells), but the cathepsin requirement and rate of cleavage differ by cell type: macrophages require cathepsins L and S jointly, while B cells require cathepsin L alone. TLR9 trafficking and processing kinetics also differ between cell types, with B cells showing faster processing and near-exclusive endolysosomal localization at rest. UNC93B1 expression level is tightly correlated with TLR9-GFP cleavage.\",\n      \"method\": \"Transgenic TLR9-GFP mice; proteolytic processing assays; cathepsin inhibitors; UNC93B1 3d mutant mice; bone marrow-derived macrophages, DCs, and B cells\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — transgenic reporter mouse plus genetic mutants plus pharmacological inhibitors, multiple cell types, rigorous mechanistic dissection\",\n      \"pmids\": [\"23241879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"DNase II digestion of DNA in endolysosomes is required for TLR9 activation by CpG-A (but not CpG-B). DNase II cleaves CpG-A from 20-mer to 11–12-mer fragments, and these 3′ 11-mer fragments can activate DNase II-deficient DCs. CpG-A shows higher colocalization with LAMP-2+ lysosomes than CpG-B, and DNase II localizes to LAMP-2+ lysosomes upon CpG-A stimulation. DNase II is also required for TLR9 activation by bacterial genomic DNA.\",\n      \"method\": \"DNase II-deficient dendritic cells; enzymatically inactive DNase II mutants; synthetic DNA fragment rescue experiments; subcellular colocalization microscopy\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — genetic knockout plus enzymatic mutant rescue plus synthetic fragment validation plus colocalization, multiple orthogonal methods in single study\",\n      \"pmids\": [\"25600358\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"BAD-LAMP (LAMP5) controls TLR9 trafficking to LAMP1+ late endosomes in human plasmacytoid dendritic cells, promoting NF-κB activation and TNF production. An inducible VAMP3+/LAMP2+/LAMP1- endolysosomal compartment exists in pDCs from which TLR9 activation triggers type I IFN expression. BAD-LAMP silencing enhances TLR9 retention in this IFN-producing compartment, whereas sustained BAD-LAMP expression promotes TLR9 sorting to late endosomes and limits type I IFN production.\",\n      \"method\": \"siRNA silencing of BAD-LAMP in primary human pDCs; subcellular compartment characterization by multi-marker imaging; cytokine output measurement\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional silencing plus compartment-resolved trafficking analysis in primary human cells, clear mechanistic dissection of IFN vs NF-κB outputs\",\n      \"pmids\": [\"29030552\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Dectin-1 controls TLR9 trafficking to phagosomes containing β-1,3 glucan. β-1,3 glucan bead recognition by Dectin-1 induces dynamic redistribution and accumulation of cleaved TLR9 to phagosomes. This trafficking requires phagosomal acidification and Dectin-1-mediated spleen tyrosine kinase (Syk) activation. Dectin-1 also regulates TLR9-dependent gene expression.\",\n      \"method\": \"Live-cell imaging; pharmacological inhibition of phagosomal acidification; Syk inhibitors; Dectin-1-dependent trafficking assays with fungal pathogens\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct trafficking imaging plus functional inhibition, single lab, two complementary methods\",\n      \"pmids\": [\"26829985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The tetraspanin CD82 associates with TLR9 in the endoplasmic reticulum and post-ER compartments of macrophages, is essential for TLR9-dependent myddosome formation in response to CpG stimulation, and modulates TLR9-dependent NF-κB nuclear translocation and inflammatory cytokine production.\",\n      \"method\": \"Co-immunoprecipitation; myddosome formation assay; NF-κB nuclear translocation assay; CD82-deficient macrophages\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional knockout plus downstream signaling readout, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"31408613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Bruton's tyrosine kinase (BTK) is required for human dendritic cell activation via TLR9: CpG/TLR9-induced upregulation of activation markers (CD86, CD83, CD80, HLA-DR) and cytokine production (IL-6, IL-12, TNF-α, IL-10) are completely impaired in XLA patients lacking functional BTK, and BTK mediates TLR9-dependent STAT1/3 upregulation. BTK inhibition with ibrutinib phenocopies XLA in healthy DCs.\",\n      \"method\": \"Human DCs from XLA patients; ibrutinib pharmacological inhibition; cytokine ELISA; flow cytometry for activation markers; STAT1/3 western blotting\",\n      \"journal\": \"The Journal of allergy and clinical immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic patient cells plus pharmacological inhibition, consistent phenotype across two orthogonal loss-of-function approaches\",\n      \"pmids\": [\"24612681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"RNA:DNA hybrids are a novel molecular pattern specifically sensed by TLR9. Hybrid-induced pro-inflammatory cytokine and type I IFN production in dendritic cells requires MyD88-dependent signaling, demonstrating TLR9 as the sensor.\",\n      \"method\": \"Cytokine induction in dendritic cells with viral-derived RNA:DNA hybrids; MyD88-deficient cells; TLR9-specific pathway analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic MyD88 knockout plus ligand specificity testing, single lab, two complementary methods\",\n      \"pmids\": [\"24514026\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TLR9 undergoes a cycle of S-palmitoylation and depalmitoylation that controls its signaling. DHHC3 (protein acyltransferase) palmitoylates TLR9 at C258 and C265 in the Golgi and regulates TLR9 trafficking to endosomes. PPT1 (palmitoyl-protein thioesterase 1) removes S-palmitoylation from TLR9 in lysosomes and facilitates TLR9 release from UNC93B1. PPT1 deficiency or inhibition reduces TLR9-dependent IFNα and TNF production.\",\n      \"method\": \"Mass spectrometry for palmitoylation site identification; biochemical palmitoylation assays; DHHC3 and PPT1 genetic/chemical manipulation; TLR9 trafficking assays; murine lupus model (B6.Sle1yaa); ex vivo human pDC experiments\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mass spectrometry site identification plus mutagenesis plus genetic knockout models plus pharmacological validation, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"38169466\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TLR9 possesses distinct signaling modes: (1) a ligand- and MyD88-independent 'scaffold' protective function; (2) ligand-dependent but MyD88-independent regulatory signaling; and (3) MyD88-mediated proinflammatory signaling. The MyD88-independent regulatory roles are B cell-intrinsic and restrain differentiation into pathogenic age-associated B cells and plasmablasts in lupus.\",\n      \"method\": \"Two TLR9 point mutants generated in lupus-prone MRL/lpr mice (TLR9K51E lacking ligand binding; TLR9P915H lacking MyD88 binding); triple-mixed bone marrow chimeras; disease phenotyping\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — structure-function point mutants in vivo plus bone marrow chimeras, multiple genetic controls enabling functional dissection of distinct signaling modes\",\n      \"pmids\": [\"36151396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TLR9 interacts with beclin 1 and this interaction increases during energy stress (glucose starvation, endurance exercise). TLR9 regulates assembly of the endolysosomal PI3KC3-C2 complex (containing beclin 1 and UVRAG) in skeletal muscle during exercise. TLR9-deficient mice fail to activate AMPK in skeletal muscle during exercise and show reduced GLUT4 plasma membrane localization, but autophagy is not impaired. TLR9 functions cell-autonomously in ex vivo contraction-induced AMPK activation and glucose uptake.\",\n      \"method\": \"TLR9-knockout mice; Co-IP of TLR9 with beclin 1; ex vivo skeletal muscle contraction; AMPK activation assays; GLUT4 localization; beclin 1 and UVRAG conditional knockouts; BCL2 mutant mice\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — Co-IP plus multiple genetic knockouts plus ex vivo contraction model, multiple orthogonal methods establishing non-immune function in skeletal muscle\",\n      \"pmids\": [\"32051584\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"During inflammatory preconditioning in neutrophils, TLR9 undergoes membrane translocation from the cytosol to the plasma membrane, where it binds to Cav-1. This TLR9-Cav-1 interaction enables TLR9 to facilitate MyD88-mediated TRAF3 and IRF3 signal transduction. Depletion of either TLR9 or Cav-1 eliminates the protective effect.\",\n      \"method\": \"Co-IP; fluorescence microscopy; FRET; flow cytometry; TLR9 and Cav-1 knockout models; sepsis models in vitro and in vivo\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, FRET, and genetic knockouts, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"31534550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MAL (MyD88 adapter-like) adapter protein is engaged in TLR9-dependent IFNβ and TNFα expression in macrophages infected with HSV-1 or treated with CpG-C, acting through a non-canonical NF-κB pathway. ERK1/2 kinases are required for TLR9-dependent IFNβ and TNFα induction via this pathway.\",\n      \"method\": \"MAL-deficient macrophages; ERK1/2 inhibitor; HSV-1 infection and CpG-C stimulation; cytokine measurement; NF-κB pathway analysis\",\n      \"journal\": \"Journal of innate immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout plus pharmacological inhibition with consistent phenotype, single lab\",\n      \"pmids\": [\"31851971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Dengue virus (an RNA virus) activates TLR9 in human dendritic cells by inducing release of mitochondrial DNA (mtDNA) into the cytosol. DENV infection disrupts TFAM-mtDNA association and activates mitochondrial permeability transition pores to release mtDNA; this activates TLR9 signaling leading to IFN production. TLR9 and cGAS comparably contribute to DENV-induced immune activation.\",\n      \"method\": \"TLR9 siRNA knockdown; TLR9-knockout bone marrow-derived DCs; side-by-side comparison with cGAS knockdown; mtDNA release assays; IFN measurement\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO plus siRNA knockdown plus mechanistic mtDNA release characterization, single lab\",\n      \"pmids\": [\"29880709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Opa1 deficiency in muscle causes mitochondrial DNA release, which activates TLR9, leading to NF-κB activation and inflammation. Blockage or repression of TLR9 prevents NF-κB activation and inflammation in Opa1-deficient muscle cells, demonstrating TLR9 as the mediator upstream of NF-κB in this pathway. This process is cell-autonomous and independent of cell death.\",\n      \"method\": \"Muscle-specific Opa1 knockout mice; TLR9 knockdown/blockade; mtDNA depletion; NF-κB reporter assays; inflammatory gene expression\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout plus pharmacological blockade plus mtDNA depletion rescue, single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"29632021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TLR9-induced type I IFN mediates anti-inflammatory effects in experimental colitis. TLR9 or MyD88 deficiency abolishes the protective effect of probiotics and probiotic DNA. Neutralizing type I IFN antibodies abrogate TLR9-mediated anti-inflammatory effects, while recombinant IFN-β mimics them.\",\n      \"method\": \"TLR9-/- and MyD88-/- mice; anti-IFN neutralizing antibodies; recombinant IFN-β administration; DSS colitis model\",\n      \"journal\": \"Annals of the New York Academy of Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout plus antibody neutralization plus cytokine rescue, single lab\",\n      \"pmids\": [\"17057215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Hepatocyte-derived mitochondrial DNA (mtDNA) in microparticles activates TLR9 in NASH. NASH development in response to high-fat diet requires TLR9 on lysozyme-expressing cells. Removal of mtDNA-containing microparticles from plasma substantially reduces TLR9 activation capacity.\",\n      \"method\": \"TLR9 conditional knockout on lysozyme+ cells; microparticle depletion from plasma; TLR9 activation assays with NASH patient plasma; TLR9 antagonist treatment\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific genetic knockout plus ligand identification plus pharmacological antagonism plus human patient plasma validation, multiple orthogonal methods\",\n      \"pmids\": [\"26808498\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TLR9-dependent signaling in pneumococcal pneumonia induces KLF4 expression via a bacterial DNA-TLR9-MyD88-Src kinase pathway. KLF4 is recruited to the IL-10 promoter and is required for IL-10 expression during pneumococcal infection; siRNA knockdown of KLF4 blocks IL-10 induction.\",\n      \"method\": \"siRNA knockdown; chromatin immunoprecipitation; Western blot; ELISA; TLR9/MyD88 pathway inhibition; murine pneumonia model\",\n      \"journal\": \"The European respiratory journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus siRNA knockdown plus genetic pathway analysis, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"22653776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TLR9 signaling plays a role in memory formation: hippocampal CA1 neurons with learning-induced double-stranded DNA breaks and nuclear envelope ruptures activate TLR9 signaling and accumulate centrosomal DNA damage repair complexes. Neuron-specific TLR9 knockdown impairs memory while blunting fear conditioning-induced gene expression changes in CA1 neuron clusters. TLR9 has an essential role in centrosome function, DNA damage repair, ciliogenesis, and perineuronal net formation.\",\n      \"method\": \"Neuron-specific Tlr9 knockdown; contextual fear conditioning; transcriptomic analysis of CA1 clusters; immunofluorescence for centrosomal complexes and DNA damage markers\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-type-specific knockdown with behavioral and molecular readouts, single lab, novel non-immune function\",\n      \"pmids\": [\"38538785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"EBV suppresses TLR9 expression by downregulating m6A modification of TLR9 mRNA. EBV nuclear antigen 1 (EBNA1) promotes K48-linked ubiquitin-proteasome degradation of METTL3 (m6A writer), reducing TLR9 mRNA stability. YTHDF1 acts as an m6A reader of TLR9 mRNA, enhancing TLR9 expression by promoting translation in an m6A-dependent manner.\",\n      \"method\": \"m6A modification analysis; METTL3 knockdown; YTHDF1 functional studies; ubiquitin-proteasome pathway assays; METTL3 inhibitor (STM2457); B cell proliferation and immunoglobulin assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic and pharmacological perturbations with mechanistic m6A pathway dissection, single lab\",\n      \"pmids\": [\"38537697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Oxidized mitochondrial DNA (ox-mtDNA) activates the TLR9-MyD88-inflammasome pathway in MDS hematopoietic stem and progenitor cells, demonstrated by increased lysosome formation, IRF7 translocation, ISG production, and TLR9 redistribution to the cell surface. TLR9 is necessary for ox-mtDNA-mediated NLRP3 inflammasome activation, shown by chemical inhibition and CRISPR knockout; TLR9 overexpression sensitizes cells to ox-mtDNA. TLR9 inhibition restores hematopoietic colony formation.\",\n      \"method\": \"CRISPR knockout; TLR9 lentiviral overexpression; TLR9 chemical inhibition; IRF7 translocation assay; inflammasome activation assays; colony formation assay\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO plus overexpression plus pharmacological inhibition, multiple orthogonal genetic/chemical approaches, single lab\",\n      \"pmids\": [\"36835307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"TLR9 and P2X7 are DAMP receptors upstream of NLRP3 inflammasome activation in acute pancreatitis. Genetic deletion of Tlr9 reduces pancreatic edema, inflammation, and pro-IL-1β expression. TLR9 is expressed in resident immune cells (predominantly macrophages) of the pancreas.\",\n      \"method\": \"Tlr9-/- mice; caerulein-induced pancreatitis; TLR9 antagonist IRS954; pro-IL-1β expression; histopathology\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout plus pharmacological antagonism plus epistasis with inflammasome components, single lab\",\n      \"pmids\": [\"21439959\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"B cell-intrinsic TLR9 expression is protective in lupus: TLR9 deficiency specifically in B cells exacerbates nephritis while extinguishing anti-nucleosome antibodies. B cell-specific TLR9 overexpression ameliorates nephritis. TLR9 deficiency in dendritic cells, plasmacytoid DCs, and neutrophils had no discernible effect on disease.\",\n      \"method\": \"Cell-type-specific TLR9 deletion and overexpression alleles in lupus-prone mice; nephritis histopathology; autoantibody measurement\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — complementary cell-type-specific deletion and overexpression in vivo with reciprocal phenotypes, rigorous genetic approach\",\n      \"pmids\": [\"32191633\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TLR9 ligation in pancreatic stellate cells (PSCs) induces fibrogenic transformation and secretion of CCL11, which promotes epithelial cell proliferation. TLR9 also has immune-suppressive effects in the pancreatic tumor microenvironment via induction of regulatory T cell recruitment and MDSC proliferation.\",\n      \"method\": \"TLR9 deletion mice; TLR9 ligation in isolated PSCs; CCL11 measurement; epithelial proliferation assays; immune cell characterization in tumor microenvironment\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO plus cell-type-specific stimulation plus paracrine factor identification, single lab\",\n      \"pmids\": [\"26481685\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"FCRL3 augments TLR9-mediated B cell proliferation, activation, and survival, but abrogates plasma cell differentiation and antibody production by halting BLIMP1 induction in an ERK-dependent fashion. FCRL3 ligation amplifies NF-κB and MAPK signaling cascades downstream of TLR9.\",\n      \"method\": \"FCRL3 ligation combined with CpG ODN (TLR9 agonist) in human B cells; NF-κB and MAPK signaling assays; BLIMP1 expression; ERK inhibition\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional stimulation experiments with signaling pathway readouts and specific inhibitor validation, single lab\",\n      \"pmids\": [\"23857366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Pro-inflammatory PS-ASOs require TLR9 signaling, but their innate immune activity does not correlate with TLR9 binding affinity, suggesting alternative PS-ASO binding sites on TLR9 leading to full, partial, or no activation. Extracellular proteins HMGB1, S100A8, and HRG enhance innate immune responses of PS-ASOs, suggesting PS-ASO-protein complexes are sensed by TLR9. Reducing PS content of PS-ASOs decreases innate immune responses.\",\n      \"method\": \"TLR9 binding affinity measurements; co-incubation competition assays; recombinant protein enhancement assays; PS content modulation\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — binding and activity assays without direct structural or mutagenesis confirmation of alternative binding sites, single lab\",\n      \"pmids\": [\"35848907\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TLR9 is an endosomal pattern recognition receptor that resides in the ER at rest and traffics to endolysosomes upon DNA ligand encounter; proteolytic cleavage (by cathepsins L and/or S, cell-type dependent) is universally required for activation; DNase II-generated DNA fragments are the direct TLR9 ligands in lysosomes; UNC93B1, BAD-LAMP, CD82, HRS, and DHHC3/PPT1-mediated palmitoylation cycles regulate TLR9 trafficking and compartment-specific signaling; upon activation TLR9 signals via MyD88–IRAK–TRAF6–PKD1 to activate NF-κB and MAPKs, and via IRF7 to induce type I IFNs, with MAL and BTK as additional required cofactors; ligand specificity is conferred by DNA methylation status (preferring unmethylated CpG), with RNA:DNA hybrids and oxidized/mitochondrial DNA also being recognized; CD32 can deliver extracellular DNA-immune complexes to TLR9-containing lysosomes; B cell-intrinsic TLR9 restrains pathogenic plasmablast differentiation in lupus through both MyD88-dependent proinflammatory and MyD88-independent regulatory scaffold functions; and beyond innate immunity, TLR9 interacts with beclin 1 to regulate AMPK activation and glucose uptake in skeletal muscle during exercise, and facilitates DNA damage repair at centrosomes in hippocampal neurons to support memory formation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TLR9 is an intracellular nucleic-acid pattern-recognition receptor that surveys endolysosomal compartments for DNA and initiates innate immune signaling, but its biology extends to metabolic and neuronal functions beyond immunity [#1, #14, #22]. At rest TLR9 resides in the endoplasmic reticulum and translocates to a tubular lysosomal compartment upon CpG-DNA encounter, where it binds ligand and signals [#1]. Activation universally requires proteolytic cleavage in endolysosomes, with the cathepsin requirement differing by cell type—cathepsins L and S jointly in macrophages versus cathepsin L alone in B cells—and is tightly coupled to UNC93B1 expression [#5]. Compartment-specific trafficking dictates signaling output: HRS mediates ubiquitin-dependent endolysosomal targeting [#4], BAD-LAMP (LAMP5) sorts TLR9 between late-endosomal NF-κB-driving and VAMP3+ IFN-driving compartments [#7], the tetraspanin CD82 chaperones TLR9 from the ER and enables myddosome formation [#9], and a DHHC3/PPT1 S-palmitoylation cycle at C258/C265 controls Golgi-to-endosome trafficking and release from UNC93B1 [#12]. Within lysosomes, DNase II processes CpG-A and bacterial genomic DNA into short fragments that constitute the activating ligands [#6], and TLR9 recognizes diverse DNA species including RNA:DNA hybrids and oxidized/mitochondrial DNA [#11, #17, #24]. Upon activation TLR9 assembles a MyD88–IRAK–TRAF6 complex that recruits PKD1 to drive NF-κB and MAPK activation [#2], with MAL and BTK serving as additional required cofactors for cytokine and type I IFN induction [#10, #16]. Structure-function dissection in vivo reveals that TLR9 operates through three distinct modes—a ligand- and MyD88-independent scaffold function, ligand-dependent MyD88-independent regulatory signaling, and MyD88-dependent proinflammatory signaling—and B cell-intrinsic TLR9 is protective in lupus, restraining pathogenic plasmablast and age-associated B cell differentiation [#13, #26]. Independent of immunity, TLR9 interacts with beclin 1 to regulate PI3KC3-C2 assembly and AMPK-dependent glucose uptake in exercising skeletal muscle [#14], and supports centrosomal DNA-damage repair in hippocampal neurons during memory formation [#22].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Establishing where TLR9 senses its ligand resolved why it detects intracellular rather than surface DNA, defining it as a compartmentalized receptor distinct from cell-surface TLRs.\",\n      \"evidence\": \"Fluorescent-tagged TLR9/TLR4 localization and CpG-DNA trafficking in human pDCs\",\n      \"pmids\": [\"15588423\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define the molecular machinery driving ER-to-lysosome translocation\", \"Did not address why endosomal localization is required for ligand discrimination\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identifying CD32 as a delivery receptor explained how extracellular DNA-immune complexes reach the intracellular TLR9 compartment, linking TLR9 to autoimmune activation.\",\n      \"evidence\": \"Subcellular colocalization and functional stimulation of CD32+ vs CD32- pDCs with SLE immune complexes\",\n      \"pmids\": [\"15668740\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not establish direct physical interaction between CD32 and TLR9\", \"Did not define the handoff step from CD32 to TLR9 within the lysosome\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrating that CpG-DNA can activate Akt independently of TLR9 via DNA-PKcs distinguished TLR9-dependent from TLR9-independent DNA sensing branches.\",\n      \"evidence\": \"In vitro kinase assay with purified DNA-PK, TLR9-/- and DNA-PKcs-/- macrophages, and Co-IP\",\n      \"pmids\": [\"15678105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address whether the two DNA-sensing branches cross-regulate\", \"Scope limited to Akt activation\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Placing PKD1 within the TLR9/MyD88/IRAK/TRAF6 complex identified a kinase node required to propagate signaling to NF-κB and MAPKs.\",\n      \"evidence\": \"Co-IP, siRNA knockdown, and kinase activation assays in macrophages\",\n      \"pmids\": [\"18641342\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PKD1 substrates in the pathway not defined\", \"Single cell type\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defining HRS-dependent ubiquitin-driven endolysosomal targeting and uncovering broad cofactor networks mapped the trafficking requirements for TLR9 signaling.\",\n      \"evidence\": \"Genome-wide RNAi screen with functional validation of HRS knockdown on TLR9 trafficking\",\n      \"pmids\": [\"22423970\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The ubiquitin ligase acting on TLR9 not identified\", \"Most screen hits not individually mechanistically validated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showing that proteolytic cleavage is universally required but cell-type-dependent in its cathepsin usage established processing as an obligatory activation step and explained cell-type differences in TLR9 responsiveness.\",\n      \"evidence\": \"Transgenic TLR9-GFP mice, cathepsin inhibitors, and UNC93B1 mutant mice across macrophages, DCs, and B cells\",\n      \"pmids\": [\"23241879\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the cleaved active receptor not resolved\", \"Mechanism coupling UNC93B1 level to cleavage rate not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identifying RNA:DNA hybrids as TLR9 ligands and demonstrating BTK as a required kinase broadened the ligand repertoire and the kinase requirements for TLR9-driven cytokine output.\",\n      \"evidence\": \"MyD88-deficient DCs with viral RNA:DNA hybrids; XLA patient DCs and ibrutinib inhibition\",\n      \"pmids\": [\"24514026\", \"24612681\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct hybrid binding to TLR9 not structurally shown\", \"BTK's precise position in the TLR9 signalosome not defined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Establishing that DNase II generates the short DNA fragments that actually activate TLR9 redefined the true ligand as a processed product rather than the input oligonucleotide.\",\n      \"evidence\": \"DNase II-deficient DCs, enzymatically inactive mutants, synthetic fragment rescue, and colocalization\",\n      \"pmids\": [\"25600358\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why CpG-B bypasses the DNase II requirement not fully explained\", \"Structural basis of fragment recognition not resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linking Dectin-1-driven phagosomal trafficking and identifying mtDNA-microparticle ligands extended TLR9 sensing to fungal and metabolic-disease contexts.\",\n      \"evidence\": \"Live-cell imaging with Syk inhibitors (Dectin-1); cell-type-specific TLR9 knockout and microparticle depletion in NASH\",\n      \"pmids\": [\"26829985\", \"26808498\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How phagosomal vs endosomal TLR9 pools differ functionally not defined\", \"Mechanism of mtDNA escape into microparticles not detailed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrating that BAD-LAMP sorts TLR9 between distinct endolysosomal compartments explained how a single receptor produces either NF-κB/TNF or type I IFN outputs.\",\n      \"evidence\": \"siRNA silencing of BAD-LAMP in primary human pDCs with multi-marker compartment imaging and cytokine readout\",\n      \"pmids\": [\"29030552\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How compartment identity is mechanistically converted into distinct signaling not fully defined\", \"Restricted to pDCs\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showing that mitochondrial DNA release (during RNA-virus infection or Opa1 loss) activates TLR9 established mtDNA as an endogenous danger ligand driving sterile and antiviral inflammation.\",\n      \"evidence\": \"TLR9 knockout/knockdown DCs with DENV; muscle-specific Opa1 knockout with TLR9 blockade and mtDNA depletion\",\n      \"pmids\": [\"29880709\", \"29632021\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How cytosolic mtDNA reaches endolysosomal TLR9 not defined\", \"Relative contribution of TLR9 vs cGAS context-dependent\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identifying CD82, MAL, and Cav-1 as context-specific cofactors refined the trafficking and adapter requirements for myddosome formation and IRF-directed signaling.\",\n      \"evidence\": \"Co-IP and knockout for CD82 (macrophages) and Cav-1 (neutrophils); MAL-deficient macrophages with ERK inhibition\",\n      \"pmids\": [\"31408613\", \"31851971\", \"31534550\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether these cofactors act in the same or distinct cell contexts not reconciled\", \"Direct binding interfaces not mapped\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Discovering the TLR9-beclin 1 interaction in skeletal muscle revealed a non-immune metabolic function controlling exercise-induced AMPK activation and glucose uptake.\",\n      \"evidence\": \"TLR9 knockout mice, Co-IP with beclin 1, ex vivo muscle contraction, and beclin1/UVRAG/BCL2 genetic models\",\n      \"pmids\": [\"32051584\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether this requires DNA ligand or signaling is unresolved\", \"How TLR9 senses energy stress not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Cell-type-specific genetics showed B cell-intrinsic TLR9 is protective in lupus, overturning the assumption that TLR9 is uniformly pathogenic in autoimmunity.\",\n      \"evidence\": \"Cell-type-specific TLR9 deletion and overexpression in lupus-prone mice with nephritis and autoantibody phenotyping\",\n      \"pmids\": [\"32191633\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the B cell-protective function not defined at this stage\", \"How protective and pathogenic roles are balanced unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Structure-function point mutants dissected TLR9 into ligand-independent scaffold, ligand-dependent MyD88-independent regulatory, and MyD88-dependent proinflammatory modes, mechanistically explaining its protective B-cell function.\",\n      \"evidence\": \"TLR9K51E and TLR9P915H point mutants and triple-mixed bone marrow chimeras in MRL/lpr mice\",\n      \"pmids\": [\"36151396\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular effectors of the MyD88-independent scaffold function not identified\", \"How the three modes are partitioned across cell states unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defining a DHHC3/PPT1 palmitoylation cycle and an m6A/METTL3/YTHDF1 expression circuit added post-translational and post-transcriptional layers controlling TLR9 trafficking and abundance.\",\n      \"evidence\": \"Mass spectrometry, palmitoylation-site mutagenesis, DHHC3/PPT1 manipulation, and lupus models; m6A analysis with METTL3/YTHDF1 perturbation\",\n      \"pmids\": [\"38169466\", \"38537697\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How palmitoylation state couples to specific signaling outputs not fully mapped\", \"Whether EBV-driven TLR9 suppression generalizes beyond B cells unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identifying a neuronal role for TLR9 in centrosomal DNA-damage repair during memory formation extended its function entirely outside innate immunity.\",\n      \"evidence\": \"Neuron-specific Tlr9 knockdown, fear conditioning, CA1 transcriptomics, and immunofluorescence of centrosomal repair complexes\",\n      \"pmids\": [\"38538785\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this requires canonical DNA ligand sensing not defined\", \"Mechanism linking TLR9 to centrosome and ciliogenesis function unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TLR9's distinct conformational/signaling states (scaffold vs MyD88-dependent vs IRF-driven) are structurally encoded and selected within specific subcellular compartments remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the active cleaved receptor in distinct compartments\", \"Mechanism converting compartment identity into signaling outcome not defined\", \"Unifying principle connecting immune, metabolic, and neuronal functions absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [1, 6, 11]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 2, 13]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [11, 17, 24]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [1, 9, 12]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [1, 5, 6, 7]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [4, 7, 12]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [15, 24]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1, 2, 6, 13]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 9, 16]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [13, 20, 26]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"complexes\": [\"myddosome (MyD88-IRAK-TRAF6)\", \"PI3KC3-C2 (beclin 1/UVRAG)\"],\n    \"partners\": [\"MyD88\", \"UNC93B1\", \"PKD1\", \"CD82\", \"BAD-LAMP\", \"beclin 1\", \"Cav-1\", \"DHHC3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}