{"gene":"TMEM106B","run_date":"2026-04-28T21:42:59","timeline":{"discoveries":[{"year":2012,"finding":"TMEM106B is a type II integral membrane protein with a highly glycosylated luminal domain, localizing to late endosomes and lysosomes; N-glycosylation is partially required for transport beyond the ER to late compartments; inhibition of vacuolar H+-ATPase significantly increases TMEM106B protein levels.","method":"Differential membrane extraction, sequential mutagenesis of N-glycosylation sites, subcellular fractionation, pharmacological inhibition of V-ATPase","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — multiple orthogonal biochemical methods (mutagenesis, fractionation, pharmacological) in a single rigorous study","pmids":["22511793"],"is_preprint":false},{"year":2012,"finding":"TMEM106B overexpression causes enlargement and poor acidification of endo-lysosomes, impairs mannose-6-phosphate-receptor trafficking, and colocalizes with progranulin in late endo-lysosomes; overexpression increases intracellular progranulin levels; microRNA-132 and microRNA-212 repress TMEM106B expression through shared binding sites in the TMEM106B 3'UTR.","method":"Overexpression in neuronal cells, live-cell imaging of lysosomes, miRNA microarray screen, luciferase reporter assay for 3'UTR binding, progranulin protein quantification","journal":"The Journal of neuroscience : the official journal of the Society for Neuroscience","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (imaging, reporter assay, protein quantification) replicating consistent findings","pmids":["22895706"],"is_preprint":false},{"year":2012,"finding":"TMEM106B localizes to late endosome/lysosome compartments and its protein levels are regulated by lysosomal activities; ectopic TMEM106B expression induces lysosomal morphological changes and delays degradation of endocytic cargoes; overexpression elevates intracellular progranulin levels, possibly by attenuating lysosomal degradation.","method":"Subcellular fractionation, immunofluorescence colocalization, overexpression with endocytic cargo degradation assays, progranulin protein measurement","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal assays with clean gain-of-function phenotypes, replicating findings from concurrent work","pmids":["23136129"],"is_preprint":false},{"year":2013,"finding":"TMEM106B knockdown in primary neurons impairs lysosomal trafficking and reduces dendritic arborization; TMEM106B physically interacts with microtubule-associated protein 6 (MAP6); MAP6 knockdown rescues the dendritic phenotype of TMEM106B knockdown; TMEM106B/MAP6 interaction controls dendritic lysosomal transport by acting as a brake on retrograde transport; expression of dominant-negative RILP (Rab7-interacting lysosomal protein) also rescues dendrite loss in TMEM106B knockdown neurons.","method":"shRNA knockdown in primary neurons, live imaging of lysosomal transport, co-immunoprecipitation (TMEM106B–MAP6 interaction), genetic epistasis via MAP6 knockdown and dominant-negative RILP","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus live imaging plus epistasis rescue in primary neurons","pmids":["24357581"],"is_preprint":false},{"year":2013,"finding":"The disease-risk variant T185 TMEM106B protein is degraded more slowly than the protective S185 variant, likely due to differences in N-glycosylation at residue N183, resulting in higher steady-state protein levels for the risk isoform.","method":"Cycloheximide chase experiments, overexpression of T185 vs. S185 variants, ELISA for protein levels, glycosylation analysis","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — direct biochemical measurement with cycloheximide chase and multiple readouts, single lab","pmids":["23742080"],"is_preprint":false},{"year":2014,"finding":"TMEM106B undergoes regulated intramembrane proteolysis: it is first processed by lysosomal proteases to an N-terminal fragment containing the transmembrane and intracellular domains, which is then cleaved by the GxGD aspartyl proteases SPPL2a (and to a lesser extent SPPL2b) to generate a small intracellular domain that is rapidly degraded.","method":"Cell-based cleavage assays, pharmacological inhibition of lysosomal proteases, overexpression of SPPL2a/SPPL2b, domain-deletion mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — identified specific protease (SPPL2a), confirmed with multiple inhibitor and overexpression experiments","pmids":["24872421"],"is_preprint":false},{"year":2015,"finding":"TMEM106B physically associates with CHMP2B (an ESCRT-III component); the disease-risk T185 variant localizes more to Rab7-positive late endosomes and shows greater association with CHMP2B compared to the protective S185 variant; T185 slightly enhances autophagic flux impairment and EGFR accumulation caused by mutant CHMP2B.","method":"Co-immunoprecipitation, immunofluorescence colocalization with Rab5/Rab7 markers, autophagic flux assay, EGFR degradation assay","journal":"Molecular brain","confidence":"Medium","confidence_rationale":"Tier 3 — single Co-IP plus colocalization with partial functional follow-up, single lab","pmids":["26651479"],"is_preprint":false},{"year":2016,"finding":"Increased TMEM106B expression causes a vacuolar phenotype in neurons and other cell types, impairs lysosomal acidification and degradative function, and increases cytotoxicity; a lysosomal sorting motif in TMEM106B is required for these effects (abrogation of lysosomal sorting rescues defects); TMEM106B-induced lysosomal defects are dependent on C9orf72, as C9orf72 knockdown rescues them.","method":"TMEM106B overexpression with lysosomal pH measurements, cell viability assays, mutagenesis of sorting motif, C9orf72 siRNA knockdown epistasis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 1–2 — mutagenesis of functional motif, genetic epistasis, multiple readouts in a single study","pmids":["27126638"],"is_preprint":false},{"year":2017,"finding":"TMEM106B physically binds vacuolar-ATPase accessory protein 1 (AP1); TMEM106B deficiency reduces vacuolar-ATPase AP1 and V0 subunits, impairing lysosomal acidification; Grn-/- and Tmem106b-/- mice have opposite effects on lysosomal enzyme levels, and Tmem106b deletion from Grn-/- mice normalizes lysosomal protein levels and rescues FTLD-related behavioral abnormalities and retinal degeneration.","method":"Co-immunoprecipitation (TMEM106B–V-ATPase AP1), transcriptomic and proteomic analyses of mouse brain, behavioral phenotyping, lysosomal pH measurements in neurons","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 — Co-IP identifying binding partner, multi-omics, and in vivo epistasis rescue experiments","pmids":["28728022"],"is_preprint":false},{"year":2018,"finding":"TMEM106B overexpression in lung cancer cells promotes synthesis of enlarged vesicular lysosomes laden with active cathepsins in a TFEB-dependent manner, and induces calcium-dependent lysosomal exocytosis, releasing active cathepsins necessary for cancer cell invasion and metastasis.","method":"TMEM106B overexpression in lung cancer cell lines, lysosomal morphology analysis, cathepsin activity assays, TFEB transcriptional target analysis, calcium chelation experiments, in vivo metastasis assays, pharmacological cathepsin inhibition","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (gene expression, enzyme assays, in vivo) with pharmacological rescue","pmids":["30013069"],"is_preprint":false},{"year":2018,"finding":"The cytoplasmic domain of TMEM106B (residues 1–~74) is intrinsically disordered with no well-defined tertiary structure, though several segments have dynamic/nascent secondary structures and restricted backbone motions, consistent with its ability to transiently interact with diverse binding partners.","method":"CD spectroscopy, multi-dimensional NMR spectroscopy, bioinformatics analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 — NMR structural characterization, but no direct functional validation of disordered state","pmids":["30332472"],"is_preprint":false},{"year":2018,"finding":"TMEM106B knockdown with antisense oligonucleotides rescues impaired endolysosomal trafficking and increased dendritic branching caused by physiological levels of mutant CHMP2B in neurons, demonstrating that reducing TMEM106B restores endosomal health in a frontotemporal dementia context.","method":"Antisense oligonucleotide (ASO) knockdown in primary neurons expressing mutant CHMP2B, live imaging of endolysosomal trafficking, dendritic morphology analysis","journal":"Brain : a journal of neurology","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO/KD with defined cellular phenotype rescue, single lab","pmids":["30496365"],"is_preprint":false},{"year":2020,"finding":"TMEM106B deficiency in mice causes accumulation of enlarged LAMP1-positive vacuoles at the distal end and within the axon initial segment of motor neurons, increased retrograde axonal transport of lysosomes, lipofuscin and autophagosome accumulation, and impaired facial-nerve-dependent motor performance.","method":"Tmem106b-/- mouse model, live-cell imaging of lysosomal transport, LAMP1 immunofluorescence, electron microscopy, behavioral motor testing","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — clean KO mouse model with multiple orthogonal phenotypic readouts including live transport imaging","pmids":["32160553"],"is_preprint":false},{"year":2020,"finding":"TMEM106B deficiency in mice causes myelination defects with reduced PLP and MOG protein levels; TMEM106B physically interacts with the lysosomal protease cathepsin D and is required to maintain cathepsin D levels in oligodendrocytes; TMEM106B deficiency results in lysosome clustering in the perinuclear region and decreased lysosome exocytosis and cell-surface PLP levels; the disease-causing D252N mutation abolishes lysosome enlargement and acidification induced by wild-type TMEM106B, instead stimulating perinuclear lysosomal clustering.","method":"Tmem106b-/- mouse, co-immunoprecipitation (TMEM106B–cathepsin D), lysosomal pH assay, lysosome exocytosis assay, surface PLP quantification, D252N mutant overexpression","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 1–2 — Co-IP identifying binding partner, multiple functional assays, mutagenesis of disease variant","pmids":["32572497"],"is_preprint":false},{"year":2020,"finding":"Loss of TMEM106B in mice causes a block late in autophagy by disrupting autophagosome-to-autolysosome maturation, coinciding with impaired lysosomal acidification, reduced cathepsin activity, and juxtanuclear clustering of lysosomes via Rab7A-dependent reduced Arl8b-mediated anterograde transport; increasing Arl8b activity restores lysosomal distribution and rescues autophagy.","method":"TMEM106B knockdown in cell models and C9ALS/FTD-derived iAstrocytes, autophagy flux assays, lysosomal pH measurements, cathepsin activity assays, Rab7A/Arl8b overexpression rescue experiments","journal":"Frontiers in cellular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — multiple mechanistic assays plus genetic rescue, single lab","pmids":["36619668"],"is_preprint":false},{"year":2021,"finding":"TMEM106B is required as a proviral host factor for SARS-CoV-2 infection; TMEM106B overexpression enhances SARS-CoV-2 and pseudovirus infection, suggesting a role in viral entry into human cell lines and primary lung cells.","method":"Genome-wide CRISPR knockout screen with SARS-CoV-2, TMEM106B overexpression in cell lines, pseudovirus infection assay, single-cell RNA-seq of patient airway cells","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 — genome-wide unbiased screen validated by gain-of-function and multiple cell types","pmids":["33686287"],"is_preprint":false},{"year":2021,"finding":"The luminal domain of TMEM106B belongs to the late embryogenesis abundant-2 (LEA-2) domain superfamily, which has a conserved lipid-binding groove, predicting that TMEM106B may function as a lipid transfer protein in the lumen of late endocytic organelles.","method":"Computational homology detection using PSI-BLAST, HMMER, HHpred, and trRosetta structural prediction","journal":"Proteins","confidence":"Low","confidence_rationale":"Tier 4 — computational prediction only, no experimental validation","pmids":["34347309"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structure determination showed that residues 120–254 of TMEM106B form amyloid filaments in human brains across multiple neurodegenerative diseases and in normal aging; three distinct TMEM106B fold conformers were identified; filaments correlate with a 29-kDa sarkosyl-insoluble C-terminal fragment and form in an age-dependent manner.","method":"Cryogenic electron microscopy structure determination from post-mortem human brain extracts, sarkosyl fractionation, immunoblotting with C-terminal antibody","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — atomic-resolution cryo-EM structures from multiple disease and normal brains, independently replicated","pmids":["35344985"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM of amyloid fibrils extracted from FTLD-TDP brains showed they are composed of a 135-residue C-terminal fragment of TMEM106B, not TDP-43; TDP-43 was detected as non-fibrillar aggregates by immunogold labelling.","method":"Cryo-electron microscopy structure determination from FTLD-TDP brain extracts, immunogold labelling for TDP-43","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — atomic-resolution cryo-EM with orthogonal immunogold validation","pmids":["35344984"],"is_preprint":false},{"year":2022,"finding":"A 135 amino acid C-terminal fragment of TMEM106B forms amyloid fibrils (solved at 2.7 Å resolution) as a common finding in FTLD-TDP, PSP, and DLB, demonstrating homotypic fibrillization of TMEM106B across diverse neurodegenerative diseases.","method":"Cryoelectron microscopy and mass spectrometry from postmortem human brain tissue from multiple disease groups","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 — high-resolution cryo-EM structures replicated across disease groups and labs","pmids":["35247328"],"is_preprint":false},{"year":2022,"finding":"TMEM106B deficiency impairs cerebellar myelination with reduced PLP and MOG levels, and causes loss of synapses between Purkinje and deep cerebellar nuclei neurons in young mice; aged TMEM106B-deficient mice show loss of Purkinje neurons in the anterior cerebellar lobe; TMEM106B deficiency causes distinct cell-type-specific lysosomal phenotypes.","method":"Tmem106b-/- mouse model, immunofluorescence, electron microscopy, synapse quantification, behavioral analysis","journal":"Acta neuropathologica communications","confidence":"High","confidence_rationale":"Tier 2 — clean KO mouse with multiple defined cellular readouts","pmids":["35287730"],"is_preprint":false},{"year":2023,"finding":"TMEM106B serves as an ACE2-independent receptor for SARS-CoV-2 entry: the luminal domain (LD) of TMEM106B directly engages the receptor-binding motif of SARS-CoV-2 spike protein; spike substitution E484D enhances TMEM106B binding and TMEM106B-mediated entry; TMEM106B-specific monoclonal antibodies block SARS-CoV-2 infection; TMEM106B promotes spike-mediated syncytium formation, suggesting a role in viral membrane fusion.","method":"X-ray crystallography and cryo-EM of TMEM106B LD–spike complex, HDX-MS, monoclonal antibody blocking assays, pseudovirus entry in ACE2-negative cells, syncytium formation assay","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 — atomic structures by multiple methods, mutagenesis, and antibody functional validation","pmids":["37421949"],"is_preprint":false},{"year":2023,"finding":"TMEM106B deficiency in mice reduces microglia proliferation and activation, increases microglial apoptosis in response to demyelination, increases lysosomal pH and decreases lysosomal enzyme activities in microglia, and significantly decreases TREM2 protein levels; microglial-specific ablation of TMEM106B produces similar phenotypes and myelination defects.","method":"Tmem106b-/- mouse, microglial-specific conditional KO mouse, lysosomal pH assay, TREM2 western blot, immunohistochemistry for microglia markers, demyelination challenge","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 — global and cell-type-specific KO with multiple defined mechanistic readouts","pmids":["37146150"],"is_preprint":false},{"year":2024,"finding":"TMEM106B physically interacts with galactosylceramidase (co-immunoprecipitation); TMEM106B deficiency significantly increases galactosylceramidase activity and decreases levels of galactosylceramide and sulfatide (major myelin lipids) in mouse brain, indicating that TMEM106B regulates myelin lipid metabolism through interaction with galactosylceramidase.","method":"Lipidomic analysis of Tmem106b-/- mouse brain, co-immunoprecipitation of TMEM106B and galactosylceramidase, galactosylceramidase enzyme activity assay","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 2 — Co-IP identifying binding partner validated by enzyme activity and lipidomics","pmids":["39237682"],"is_preprint":false},{"year":2024,"finding":"Lysosomal cysteine-type proteases perform the initial cleavage of TMEM106B's luminal domain (generating the C-terminal fragment capable of fibril formation) and also perform additional C-terminal trimming; this shedding occurs physiologically and is detectable in cellular and mouse models.","method":"Antibody development against luminal domain, pharmacological inhibition of specific protease classes, cellular and TMEM106B-related mouse models, human autopsy tissue immunoblotting","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1 — protease class identified with pharmacological inhibitors, multiple model systems","pmids":["39709600"],"is_preprint":false},{"year":2024,"finding":"TMEM106B deletion in a P301S tau mouse model accelerates cognitive decline, hind limb paralysis, tau pathology, and neurodegeneration; the T185S coding variant (knock-in) protects against tau-associated cognitive decline, synaptic impairment, neurodegeneration, and paralysis without affecting tau pathology itself, demonstrating that TMEM106B acts downstream of tau aggregation to preserve neuronal function.","method":"Tmem106b-/- and T186S knock-in mice crossed with P301S tau transgenic mice, behavioral testing, tau pathology quantification, synaptic protein analysis, transcriptomics","journal":"Acta neuropathologica","confidence":"High","confidence_rationale":"Tier 2 — both KO and knock-in (coding variant) crossed with disease model, multiple phenotypic readouts","pmids":["38526616"],"is_preprint":false},{"year":2024,"finding":"TMEM106B C-terminal fragment core accumulation in FTLD-TDP postmortem brain is associated with TDP-43 dysfunction; carriers of the risk genotype (rs3173615) show higher TMEM106B core deposition, while protective allele carriers show minimal core deposition and an increase in dimeric full-length TMEM106B; interactome data implicate TMEM106B core filaments in impaired RNA transport, local translation, and endolysosomal function.","method":"Novel antibody targeting TMEM106B filament core, immunoblotting of postmortem FTLD-TDP samples stratified by rs3173615 genotype, interactome proteomics","journal":"Science translational medicine","confidence":"Medium","confidence_rationale":"Tier 2 — direct measurement in human tissue with genotype stratification and proteomics, single study","pmids":["38232138"],"is_preprint":false},{"year":2024,"finding":"TMEM106B loss in Tmem106b-/- PS19 (P301S tau) mice enhances accumulation of pathological tau in neuronal soma in the hippocampus, causes severe neuronal loss, and exacerbates abnormalities in neuronal cytoskeleton, autophagy-lysosome activities, and glial activation compared to PS19 alone.","method":"Tmem106b-/- × PS19 double-mutant mice, tau immunohistochemistry and pathology scoring, lysosomal/autophagy marker analysis, neuronal counting, glial activation assays","journal":"Acta neuropathologica","confidence":"High","confidence_rationale":"Tier 2 — clean double-KO/transgenic model with multiple mechanistic readouts, replicates findings from independent concurrent study","pmids":["38526799"],"is_preprint":false},{"year":2022,"finding":"TMEM106B C-terminal fragment aggregates form amyloid inclusions (confirmed by luminescent conjugated oligothiophene staining) predominantly in astrocytes in the brain parenchyma, and also in dorsal root ganglia and spinal cord non-neuronal cells; by in situ immunoelectron microscopy, TMEM106B assemblies are found in structures resembling endosomes and lysosomes; a second cleavage beyond residue 120 is indicated by antibody staining at residues 263–274.","method":"Immunohistochemistry with TMEM106B-specific antibodies, luminescent conjugated oligothiophene (LCO) staining, transmission immuno-electron microscopy, tissue distribution analysis","journal":"Acta neuropathologica communications","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization by immunoelectron microscopy with functional implication for lysosomal origin of fibrils","pmids":["38886865"],"is_preprint":false}],"current_model":"TMEM106B is a type II lysosomal transmembrane protein whose luminal domain (residues 120–254) is cleaved by lysosomal cysteine proteases (and further processed by SPPL2a-mediated intramembrane proteolysis) to generate a C-terminal fragment that forms amyloid fibrils in an age-dependent manner; at the lysosomal membrane, TMEM106B regulates lysosomal acidification (through interaction with the vacuolar-ATPase), myelin lipid metabolism (through interaction with galactosylceramidase), cathepsin D levels, anterograde lysosomal transport in axons and dendrites (via MAP6 and Arl8b-dependent pathways), lysosomal exocytosis, TFEB-driven lysosomal biogenesis, microglial TREM2 levels and survival, and can also serve as an ACE2-independent receptor for SARS-CoV-2 entry through direct engagement of its luminal domain with the viral spike receptor-binding motif."},"narrative":{"teleology":[{"year":2012,"claim":"Establishing TMEM106B as a glycosylated type II lysosomal membrane protein whose overexpression impairs endo-lysosomal acidification and degradative function resolved the basic topology and organellar context of a gene previously known only from GWAS.","evidence":"Biochemical fractionation, glycosylation-site mutagenesis, V-ATPase inhibition, overexpression with lysosomal pH and cargo degradation assays in neuronal and non-neuronal cells","pmids":["22511793","22895706","23136129"],"confidence":"High","gaps":["No endogenous loss-of-function data yet","Mechanism linking TMEM106B to V-ATPase not identified","Relevance to human disease beyond GWAS association unresolved"]},{"year":2013,"claim":"Identifying MAP6 as a physical interactor and demonstrating that TMEM106B controls dendritic lysosomal transport revealed a direct mechanistic link between TMEM106B and neuronal morphology, explaining how lysosomal positioning defects translate to dendritic arborization phenotypes.","evidence":"Reciprocal co-immunoprecipitation of TMEM106B–MAP6, live lysosomal transport imaging, and MAP6/RILP epistasis rescue in primary neurons","pmids":["24357581"],"confidence":"High","gaps":["Whether MAP6 interaction is direct or bridged remains unclear","Axonal transport effects not yet tested","No structural basis for the interaction"]},{"year":2014,"claim":"Discovery that TMEM106B undergoes regulated intramembrane proteolysis—first by lysosomal proteases, then by SPPL2a—identified a processing pathway that would later prove critical for understanding amyloid fibril generation from the cleaved C-terminal fragment.","evidence":"Cell-based cleavage assays with pharmacological inhibitors and SPPL2a/2b overexpression, domain-deletion mutagenesis","pmids":["24872421"],"confidence":"High","gaps":["Identity of the initial lysosomal protease unresolved","Physiological triggers for cleavage unknown","Fate and function of the released intracellular domain unclear"]},{"year":2017,"claim":"Demonstrating that TMEM106B physically binds the V-ATPase AP1 subunit and that Tmem106b deletion rescues lysosomal and behavioral defects of Grn−/− mice mechanistically connected TMEM106B to lysosomal acidification and established its genetic interaction with progranulin in vivo.","evidence":"Co-immunoprecipitation of TMEM106B–V-ATPase AP1, multi-omics of mouse brain, behavioral rescue in Grn−/−;Tmem106b−/− double-knockout mice","pmids":["28728022"],"confidence":"High","gaps":["Stoichiometry and directness of V-ATPase interaction not resolved","Whether rescue reflects restored acidification or another mechanism uncertain"]},{"year":2018,"claim":"Showing that TMEM106B overexpression drives TFEB-dependent lysosomal biogenesis and calcium-dependent lysosomal exocytosis of active cathepsins extended its role beyond lysosomal homeostasis to a pro-invasive function in cancer cells.","evidence":"TMEM106B overexpression in lung cancer cells with cathepsin activity assays, TFEB target analysis, calcium chelation, and in vivo metastasis models","pmids":["30013069"],"confidence":"High","gaps":["Direct TMEM106B–TFEB regulatory mechanism not defined","Whether endogenous TMEM106B levels drive exocytosis in non-cancer contexts unclear"]},{"year":2020,"claim":"Studies in Tmem106b−/− mice demonstrated that loss of TMEM106B impairs axonal lysosomal distribution, myelination, cathepsin D levels, and lysosomal exocytosis in oligodendrocytes, establishing bidirectional dosage sensitivity and cell-type-specific functions including interaction with galactosylceramidase (later confirmed) and cathepsin D.","evidence":"Tmem106b−/− mice with live axonal transport imaging, PLP/MOG quantification, TMEM106B–cathepsin D co-immunoprecipitation, lysosomal exocytosis assays, D252N mutant characterization","pmids":["32160553","32572497","36619668"],"confidence":"High","gaps":["Whether myelination defect is cell-autonomous to oligodendrocytes vs. neuronal contribution unclear","Arl8b-dependent rescue awaits in vivo validation","Role of cathepsin D interaction in myelination not directly tested"]},{"year":2022,"claim":"Three independent cryo-EM studies revealed that residues 120–254 of TMEM106B form amyloid fibrils in human brains across neurodegenerative diseases and in normal aging, fundamentally redefining TMEM106B from a lysosomal regulator to an amyloid-forming protein whose aggregation is age-dependent and disease-nonspecific.","evidence":"Cryo-EM structure determination at atomic resolution from post-mortem brain extracts of FTLD-TDP, PSP, DLB, and aged controls, with immunogold and mass spectrometry validation","pmids":["35344985","35344984","35247328"],"confidence":"High","gaps":["Whether fibril formation is pathogenic, protective, or bystander remains unknown","Mechanism initiating fibril nucleation from the cleaved fragment undefined","No animal model recapitulating TMEM106B amyloid formation"]},{"year":2023,"claim":"Structural and functional evidence established TMEM106B as an ACE2-independent receptor for SARS-CoV-2, with its luminal domain directly engaging the spike receptor-binding motif, explaining its identification as a proviral host factor and expanding its function beyond lysosomal biology.","evidence":"X-ray crystallography and cryo-EM of TMEM106B LD–spike complex, monoclonal antibody blocking of infection, pseudovirus entry in ACE2-negative cells, syncytium formation assay","pmids":["37421949","33686287"],"confidence":"High","gaps":["In vivo contribution of TMEM106B-mediated entry relative to ACE2 pathway not quantified","Whether TMEM106B-mediated entry involves endosomal route exclusively is unresolved"]},{"year":2024,"claim":"Identification of lysosomal cysteine proteases as the enzymes performing initial luminal domain shedding, together with the finding that TMEM106B interacts with galactosylceramidase to regulate myelin lipid metabolism, completed two long-standing mechanistic gaps in TMEM106B processing and myelination pathways.","evidence":"Pharmacological inhibition of protease classes across cellular and mouse models; co-immunoprecipitation of TMEM106B–galactosylceramidase with lipidomics and enzyme activity assays in Tmem106b−/− brain","pmids":["39709600","39237682"],"confidence":"High","gaps":["Specific cysteine protease identity (e.g., cathepsin B vs. L) not resolved","Whether galactosylceramidase interaction is direct or within a larger complex unknown"]},{"year":2024,"claim":"Crossing Tmem106b−/− and T185S knock-in mice with P301S tau models demonstrated that TMEM106B loss exacerbates tau-driven neurodegeneration while the protective coding variant preserves neuronal function without affecting tau pathology, positioning TMEM106B as a downstream modifier of tauopathy outcome.","evidence":"Tmem106b−/− × PS19 and T186S knock-in × PS19 crosses with behavioral, histological, synaptic, and transcriptomic analyses","pmids":["38526616","38526799"],"confidence":"High","gaps":["Molecular mechanism by which T185S variant confers neuroprotection not defined","Whether the effect is mediated by reduced fibril formation, improved lysosomal function, or both is unresolved","Relevance to sporadic human tauopathies awaits further validation"]},{"year":null,"claim":"Critical open questions include whether TMEM106B amyloid fibril formation is a cause or consequence of neurodegeneration, the identity of the specific cysteine protease(s) initiating luminal domain shedding, the structural basis of TMEM106B interactions with V-ATPase and MAP6, and how TMEM106B dosage is sensed to trigger TFEB-dependent lysosomal biogenesis.","evidence":"","pmids":[],"confidence":"Low","gaps":["No causal link established between TMEM106B fibrils and neurodegeneration","No reconstituted in vitro system for fibril nucleation from membrane-bound TMEM106B","Structural basis for most protein–protein interactions unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[15,21]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8,9,14,23]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[0,1,2,7,8,13,28]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0,1,6]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[14,27]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,9,12,13]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[8,9,14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[17,18,19,25]}],"complexes":[],"partners":["MAP6","ATP6V0A1","CTSD","GALC","CHMP2B","SPPL2A"],"other_free_text":[]},"mechanistic_narrative":"TMEM106B is a type II transmembrane protein of late endosomes and lysosomes that serves as a central regulator of lysosomal biology, controlling organelle acidification, positioning, exocytosis, and cargo degradation in neurons, glia, and other cell types. At the lysosomal membrane, TMEM106B maintains acidification through physical interaction with the vacuolar H⁺-ATPase accessory protein AP1, regulates myelin lipid metabolism via interaction with galactosylceramidase, controls anterograde lysosomal transport through MAP6- and Arl8b-dependent pathways, and promotes TFEB-driven lysosomal biogenesis and cathepsin-dependent lysosomal exocytosis [PMID:28728022, PMID:39237682, PMID:24357581, PMID:36619668, PMID:30013069]. The luminal domain (residues 120–254) undergoes sequential proteolysis—first by lysosomal cysteine proteases, then by the intramembrane protease SPPL2a—generating a C-terminal fragment that accumulates as amyloid fibrils in an age-dependent manner across neurodegenerative diseases and normal aging, with the FTLD risk variant (T185) promoting higher steady-state protein levels and greater fibril core deposition [PMID:39709600, PMID:24872421, PMID:35344985, PMID:38232138]. TMEM106B also functions as an ACE2-independent entry receptor for SARS-CoV-2, with its luminal domain directly engaging the spike receptor-binding motif to facilitate viral membrane fusion [PMID:37421949]."},"prefetch_data":{"uniprot":{"accession":"Q9NUM4","full_name":"Transmembrane protein 106B","aliases":[],"length_aa":274,"mass_kda":31.1,"function":"In neurons, involved in the transport of late endosomes/lysosomes (PubMed:25066864). May be involved in dendrite morphogenesis and maintenance by regulating lysosomal trafficking (PubMed:25066864). May act as a molecular brake for retrograde transport of late endosomes/lysosomes, possibly via its interaction with MAP6 (By similarity). In motoneurons, may mediate the axonal transport of lysosomes and axonal sorting at the initial segment (By similarity). It remains unclear whether TMEM106B affects the transport of moving lysosomes in the anterograde or retrograde direction in neurites and whether it is important in the sorting of lysosomes in axons or in dendrites (By similarity). In neurons, may also play a role in the regulation of lysosomal size and responsiveness to stress (PubMed:25066864). Required for proper lysosomal acidification (By similarity) (Microbial infection) Plays a role in human coronavirus SARS-CoV-2 infection, but not in common cold coronaviruses HCoV-229E and HCoV-OC43 infections. Involved in ACE2-independent SARS-CoV-2 cell entry. Required for post-endocytic stage of virus entry, facilitates spike-mediated membrane fusion. Virus attachment and endocytosis can also be mediated by other cell surface receptors","subcellular_location":"Late endosome membrane; Lysosome membrane; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9NUM4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TMEM106B","classification":"Not 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neuropathologica communications","url":"https://pubmed.ncbi.nlm.nih.gov/36707901","citation_count":10,"is_preprint":false},{"pmid":"32595021","id":"PMC_32595021","title":"A recurrent TMEM106B mutation in hypomyelinating leukodystrophy: A rapid diagnostic assay.","date":"2020","source":"Brain & development","url":"https://pubmed.ncbi.nlm.nih.gov/32595021","citation_count":10,"is_preprint":false},{"pmid":"39911968","id":"PMC_39911968","title":"A 3'UTR Insertion Is a Candidate Causal Variant at the TMEM106B Locus Associated With Increased Risk for FTLD-TDP.","date":"2024","source":"Neurology. Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39911968","citation_count":10,"is_preprint":false},{"pmid":"38886865","id":"PMC_38886865","title":"Cleaved TMEM106B forms amyloid aggregates in central and peripheral nervous systems.","date":"2024","source":"Acta neuropathologica communications","url":"https://pubmed.ncbi.nlm.nih.gov/38886865","citation_count":9,"is_preprint":false},{"pmid":"37519899","id":"PMC_37519899","title":"AAV-GRN partially corrects motor deficits and ALS/FTLD-related pathology in Tmem106bGrn mice.","date":"2023","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/37519899","citation_count":9,"is_preprint":false},{"pmid":"25096617","id":"PMC_25096617","title":"Association of TMEM106B rs1990622 marker and frontotemporal dementia: evidence for a recessive effect and meta-analysis.","date":"2015","source":"Journal of Alzheimer's disease : JAD","url":"https://pubmed.ncbi.nlm.nih.gov/25096617","citation_count":7,"is_preprint":false},{"pmid":"30332472","id":"PMC_30332472","title":"TMEM106B, a risk factor for FTLD and aging, has an intrinsically disordered cytoplasmic domain.","date":"2018","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/30332472","citation_count":7,"is_preprint":false},{"pmid":"38710967","id":"PMC_38710967","title":"Physiological and pathological functions of TMEM106B in neurodegenerative diseases.","date":"2024","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/38710967","citation_count":6,"is_preprint":false},{"pmid":"32985120","id":"PMC_32985120","title":"Progranulin and TMEM106B: when two become wan.","date":"2020","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/32985120","citation_count":6,"is_preprint":false},{"pmid":"39711302","id":"PMC_39711302","title":"TMEM106B C-terminal fragments aggregate and drive neurodegenerative proteinopathy in transgenic Caenorhabditis elegans.","date":"2024","source":"Alzheimer's & dementia : the journal of the Alzheimer's Association","url":"https://pubmed.ncbi.nlm.nih.gov/39711302","citation_count":6,"is_preprint":false},{"pmid":"39044012","id":"PMC_39044012","title":"TMEM106B Knockdown Exhibits a Neuroprotective Effect in Parkinson's Disease via Decreasing Inflammation and Iron Deposition.","date":"2024","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/39044012","citation_count":6,"is_preprint":false},{"pmid":"37545650","id":"PMC_37545650","title":"The identification of high-performing antibodies for transmembrane protein 106B (TMEM106B) for use in Western blot, immunoprecipitation, and immunofluorescence.","date":"2023","source":"F1000Research","url":"https://pubmed.ncbi.nlm.nih.gov/37545650","citation_count":6,"is_preprint":false},{"pmid":"28888721","id":"PMC_28888721","title":"TMEM106B and ApoE polymorphisms in CHMP2B-mediated frontotemporal dementia (FTD-3).","date":"2017","source":"Neurobiology of aging","url":"https://pubmed.ncbi.nlm.nih.gov/28888721","citation_count":6,"is_preprint":false},{"pmid":"40713630","id":"PMC_40713630","title":"The role of endolysosomal progranulin and TMEM106B in neurodegenerative diseases.","date":"2025","source":"Molecular neurodegeneration","url":"https://pubmed.ncbi.nlm.nih.gov/40713630","citation_count":5,"is_preprint":false},{"pmid":"37443768","id":"PMC_37443768","title":"TMEM106B Puncta Is Increased in Multiple Sclerosis Plaques, and Reduced Protein in Mice Results in Delayed Lipid Clearance Following CNS Injury.","date":"2023","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/37443768","citation_count":5,"is_preprint":false},{"pmid":"37937069","id":"PMC_37937069","title":"Antibody-recognizing residues 188-211 of TMEM106B exhibit immunohistochemical reactivity with the TMEM106B C-terminal fragment.","date":"2023","source":"Frontiers in neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/37937069","citation_count":5,"is_preprint":false},{"pmid":"37541193","id":"PMC_37541193","title":"Unveiling TMEM106B: SARS-CoV-2's secret entrance to the cell.","date":"2023","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/37541193","citation_count":5,"is_preprint":false},{"pmid":"37965143","id":"PMC_37965143","title":"TMEM106B reduction does not rescue GRN deficiency in iPSC-derived human microglia and mouse models.","date":"2023","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/37965143","citation_count":5,"is_preprint":false},{"pmid":"38206837","id":"PMC_38206837","title":"Novel Omicron Variants Enhance Anchored Recognition of TMEM106B: A New Pathway for SARS-CoV-2 Cellular Invasion.","date":"2024","source":"The journal of physical chemistry letters","url":"https://pubmed.ncbi.nlm.nih.gov/38206837","citation_count":5,"is_preprint":false},{"pmid":"37461476","id":"PMC_37461476","title":"A 3'UTR Insertion Is a Candidate Causal Variant at the TMEM106B Locus Associated with Increased Risk for FTLD-TDP.","date":"2023","source":"medRxiv : the preprint server for health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37461476","citation_count":5,"is_preprint":false},{"pmid":"39321401","id":"PMC_39321401","title":"Gene-Specific Effects on Brain Volume and Cognition of TMEM106B in Frontotemporal Lobar Degeneration.","date":"2024","source":"Neurology","url":"https://pubmed.ncbi.nlm.nih.gov/39321401","citation_count":4,"is_preprint":false},{"pmid":"39709600","id":"PMC_39709600","title":"Physiological shedding and C-terminal proteolytic processing of TMEM106B.","date":"2024","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/39709600","citation_count":4,"is_preprint":false},{"pmid":"39503754","id":"PMC_39503754","title":"TMEM106B amyloid filaments in the Biondi bodies of ependymal cells.","date":"2024","source":"Acta neuropathologica","url":"https://pubmed.ncbi.nlm.nih.gov/39503754","citation_count":4,"is_preprint":false},{"pmid":"40011708","id":"PMC_40011708","title":"TMEM106B deficiency leads to alterations in lipid metabolism and obesity in the TDP-43Q331K knock-in mouse model.","date":"2025","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/40011708","citation_count":4,"is_preprint":false},{"pmid":"36046422","id":"PMC_36046422","title":"Severe Epilepsy and Movement Disorder May Be Early Symptoms of TMEM106B-Related Hypomyelinating Leukodystrophy.","date":"2022","source":"Neurology. Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36046422","citation_count":4,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":52755,"output_tokens":7174,"usd":0.132937},"stage2":{"model":"claude-opus-4-6","input_tokens":10861,"output_tokens":3232,"usd":0.202657},"total_usd":0.335594,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2012,\n      \"finding\": \"TMEM106B is a type II integral membrane protein with a highly glycosylated luminal domain, localizing to late endosomes and lysosomes; N-glycosylation is partially required for transport beyond the ER to late compartments; inhibition of vacuolar H+-ATPase significantly increases TMEM106B protein levels.\",\n      \"method\": \"Differential membrane extraction, sequential mutagenesis of N-glycosylation sites, subcellular fractionation, pharmacological inhibition of V-ATPase\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple orthogonal biochemical methods (mutagenesis, fractionation, pharmacological) in a single rigorous study\",\n      \"pmids\": [\"22511793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TMEM106B overexpression causes enlargement and poor acidification of endo-lysosomes, impairs mannose-6-phosphate-receptor trafficking, and colocalizes with progranulin in late endo-lysosomes; overexpression increases intracellular progranulin levels; microRNA-132 and microRNA-212 repress TMEM106B expression through shared binding sites in the TMEM106B 3'UTR.\",\n      \"method\": \"Overexpression in neuronal cells, live-cell imaging of lysosomes, miRNA microarray screen, luciferase reporter assay for 3'UTR binding, progranulin protein quantification\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (imaging, reporter assay, protein quantification) replicating consistent findings\",\n      \"pmids\": [\"22895706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TMEM106B localizes to late endosome/lysosome compartments and its protein levels are regulated by lysosomal activities; ectopic TMEM106B expression induces lysosomal morphological changes and delays degradation of endocytic cargoes; overexpression elevates intracellular progranulin levels, possibly by attenuating lysosomal degradation.\",\n      \"method\": \"Subcellular fractionation, immunofluorescence colocalization, overexpression with endocytic cargo degradation assays, progranulin protein measurement\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal assays with clean gain-of-function phenotypes, replicating findings from concurrent work\",\n      \"pmids\": [\"23136129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TMEM106B knockdown in primary neurons impairs lysosomal trafficking and reduces dendritic arborization; TMEM106B physically interacts with microtubule-associated protein 6 (MAP6); MAP6 knockdown rescues the dendritic phenotype of TMEM106B knockdown; TMEM106B/MAP6 interaction controls dendritic lysosomal transport by acting as a brake on retrograde transport; expression of dominant-negative RILP (Rab7-interacting lysosomal protein) also rescues dendrite loss in TMEM106B knockdown neurons.\",\n      \"method\": \"shRNA knockdown in primary neurons, live imaging of lysosomal transport, co-immunoprecipitation (TMEM106B–MAP6 interaction), genetic epistasis via MAP6 knockdown and dominant-negative RILP\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus live imaging plus epistasis rescue in primary neurons\",\n      \"pmids\": [\"24357581\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The disease-risk variant T185 TMEM106B protein is degraded more slowly than the protective S185 variant, likely due to differences in N-glycosylation at residue N183, resulting in higher steady-state protein levels for the risk isoform.\",\n      \"method\": \"Cycloheximide chase experiments, overexpression of T185 vs. S185 variants, ELISA for protein levels, glycosylation analysis\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct biochemical measurement with cycloheximide chase and multiple readouts, single lab\",\n      \"pmids\": [\"23742080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TMEM106B undergoes regulated intramembrane proteolysis: it is first processed by lysosomal proteases to an N-terminal fragment containing the transmembrane and intracellular domains, which is then cleaved by the GxGD aspartyl proteases SPPL2a (and to a lesser extent SPPL2b) to generate a small intracellular domain that is rapidly degraded.\",\n      \"method\": \"Cell-based cleavage assays, pharmacological inhibition of lysosomal proteases, overexpression of SPPL2a/SPPL2b, domain-deletion mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — identified specific protease (SPPL2a), confirmed with multiple inhibitor and overexpression experiments\",\n      \"pmids\": [\"24872421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TMEM106B physically associates with CHMP2B (an ESCRT-III component); the disease-risk T185 variant localizes more to Rab7-positive late endosomes and shows greater association with CHMP2B compared to the protective S185 variant; T185 slightly enhances autophagic flux impairment and EGFR accumulation caused by mutant CHMP2B.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence colocalization with Rab5/Rab7 markers, autophagic flux assay, EGFR degradation assay\",\n      \"journal\": \"Molecular brain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP plus colocalization with partial functional follow-up, single lab\",\n      \"pmids\": [\"26651479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Increased TMEM106B expression causes a vacuolar phenotype in neurons and other cell types, impairs lysosomal acidification and degradative function, and increases cytotoxicity; a lysosomal sorting motif in TMEM106B is required for these effects (abrogation of lysosomal sorting rescues defects); TMEM106B-induced lysosomal defects are dependent on C9orf72, as C9orf72 knockdown rescues them.\",\n      \"method\": \"TMEM106B overexpression with lysosomal pH measurements, cell viability assays, mutagenesis of sorting motif, C9orf72 siRNA knockdown epistasis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — mutagenesis of functional motif, genetic epistasis, multiple readouts in a single study\",\n      \"pmids\": [\"27126638\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TMEM106B physically binds vacuolar-ATPase accessory protein 1 (AP1); TMEM106B deficiency reduces vacuolar-ATPase AP1 and V0 subunits, impairing lysosomal acidification; Grn-/- and Tmem106b-/- mice have opposite effects on lysosomal enzyme levels, and Tmem106b deletion from Grn-/- mice normalizes lysosomal protein levels and rescues FTLD-related behavioral abnormalities and retinal degeneration.\",\n      \"method\": \"Co-immunoprecipitation (TMEM106B–V-ATPase AP1), transcriptomic and proteomic analyses of mouse brain, behavioral phenotyping, lysosomal pH measurements in neurons\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP identifying binding partner, multi-omics, and in vivo epistasis rescue experiments\",\n      \"pmids\": [\"28728022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TMEM106B overexpression in lung cancer cells promotes synthesis of enlarged vesicular lysosomes laden with active cathepsins in a TFEB-dependent manner, and induces calcium-dependent lysosomal exocytosis, releasing active cathepsins necessary for cancer cell invasion and metastasis.\",\n      \"method\": \"TMEM106B overexpression in lung cancer cell lines, lysosomal morphology analysis, cathepsin activity assays, TFEB transcriptional target analysis, calcium chelation experiments, in vivo metastasis assays, pharmacological cathepsin inhibition\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (gene expression, enzyme assays, in vivo) with pharmacological rescue\",\n      \"pmids\": [\"30013069\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The cytoplasmic domain of TMEM106B (residues 1–~74) is intrinsically disordered with no well-defined tertiary structure, though several segments have dynamic/nascent secondary structures and restricted backbone motions, consistent with its ability to transiently interact with diverse binding partners.\",\n      \"method\": \"CD spectroscopy, multi-dimensional NMR spectroscopy, bioinformatics analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — NMR structural characterization, but no direct functional validation of disordered state\",\n      \"pmids\": [\"30332472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TMEM106B knockdown with antisense oligonucleotides rescues impaired endolysosomal trafficking and increased dendritic branching caused by physiological levels of mutant CHMP2B in neurons, demonstrating that reducing TMEM106B restores endosomal health in a frontotemporal dementia context.\",\n      \"method\": \"Antisense oligonucleotide (ASO) knockdown in primary neurons expressing mutant CHMP2B, live imaging of endolysosomal trafficking, dendritic morphology analysis\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO/KD with defined cellular phenotype rescue, single lab\",\n      \"pmids\": [\"30496365\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TMEM106B deficiency in mice causes accumulation of enlarged LAMP1-positive vacuoles at the distal end and within the axon initial segment of motor neurons, increased retrograde axonal transport of lysosomes, lipofuscin and autophagosome accumulation, and impaired facial-nerve-dependent motor performance.\",\n      \"method\": \"Tmem106b-/- mouse model, live-cell imaging of lysosomal transport, LAMP1 immunofluorescence, electron microscopy, behavioral motor testing\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO mouse model with multiple orthogonal phenotypic readouts including live transport imaging\",\n      \"pmids\": [\"32160553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TMEM106B deficiency in mice causes myelination defects with reduced PLP and MOG protein levels; TMEM106B physically interacts with the lysosomal protease cathepsin D and is required to maintain cathepsin D levels in oligodendrocytes; TMEM106B deficiency results in lysosome clustering in the perinuclear region and decreased lysosome exocytosis and cell-surface PLP levels; the disease-causing D252N mutation abolishes lysosome enlargement and acidification induced by wild-type TMEM106B, instead stimulating perinuclear lysosomal clustering.\",\n      \"method\": \"Tmem106b-/- mouse, co-immunoprecipitation (TMEM106B–cathepsin D), lysosomal pH assay, lysosome exocytosis assay, surface PLP quantification, D252N mutant overexpression\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — Co-IP identifying binding partner, multiple functional assays, mutagenesis of disease variant\",\n      \"pmids\": [\"32572497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Loss of TMEM106B in mice causes a block late in autophagy by disrupting autophagosome-to-autolysosome maturation, coinciding with impaired lysosomal acidification, reduced cathepsin activity, and juxtanuclear clustering of lysosomes via Rab7A-dependent reduced Arl8b-mediated anterograde transport; increasing Arl8b activity restores lysosomal distribution and rescues autophagy.\",\n      \"method\": \"TMEM106B knockdown in cell models and C9ALS/FTD-derived iAstrocytes, autophagy flux assays, lysosomal pH measurements, cathepsin activity assays, Rab7A/Arl8b overexpression rescue experiments\",\n      \"journal\": \"Frontiers in cellular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple mechanistic assays plus genetic rescue, single lab\",\n      \"pmids\": [\"36619668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TMEM106B is required as a proviral host factor for SARS-CoV-2 infection; TMEM106B overexpression enhances SARS-CoV-2 and pseudovirus infection, suggesting a role in viral entry into human cell lines and primary lung cells.\",\n      \"method\": \"Genome-wide CRISPR knockout screen with SARS-CoV-2, TMEM106B overexpression in cell lines, pseudovirus infection assay, single-cell RNA-seq of patient airway cells\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide unbiased screen validated by gain-of-function and multiple cell types\",\n      \"pmids\": [\"33686287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The luminal domain of TMEM106B belongs to the late embryogenesis abundant-2 (LEA-2) domain superfamily, which has a conserved lipid-binding groove, predicting that TMEM106B may function as a lipid transfer protein in the lumen of late endocytic organelles.\",\n      \"method\": \"Computational homology detection using PSI-BLAST, HMMER, HHpred, and trRosetta structural prediction\",\n      \"journal\": \"Proteins\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational prediction only, no experimental validation\",\n      \"pmids\": [\"34347309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structure determination showed that residues 120–254 of TMEM106B form amyloid filaments in human brains across multiple neurodegenerative diseases and in normal aging; three distinct TMEM106B fold conformers were identified; filaments correlate with a 29-kDa sarkosyl-insoluble C-terminal fragment and form in an age-dependent manner.\",\n      \"method\": \"Cryogenic electron microscopy structure determination from post-mortem human brain extracts, sarkosyl fractionation, immunoblotting with C-terminal antibody\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — atomic-resolution cryo-EM structures from multiple disease and normal brains, independently replicated\",\n      \"pmids\": [\"35344985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM of amyloid fibrils extracted from FTLD-TDP brains showed they are composed of a 135-residue C-terminal fragment of TMEM106B, not TDP-43; TDP-43 was detected as non-fibrillar aggregates by immunogold labelling.\",\n      \"method\": \"Cryo-electron microscopy structure determination from FTLD-TDP brain extracts, immunogold labelling for TDP-43\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — atomic-resolution cryo-EM with orthogonal immunogold validation\",\n      \"pmids\": [\"35344984\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A 135 amino acid C-terminal fragment of TMEM106B forms amyloid fibrils (solved at 2.7 Å resolution) as a common finding in FTLD-TDP, PSP, and DLB, demonstrating homotypic fibrillization of TMEM106B across diverse neurodegenerative diseases.\",\n      \"method\": \"Cryoelectron microscopy and mass spectrometry from postmortem human brain tissue from multiple disease groups\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution cryo-EM structures replicated across disease groups and labs\",\n      \"pmids\": [\"35247328\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TMEM106B deficiency impairs cerebellar myelination with reduced PLP and MOG levels, and causes loss of synapses between Purkinje and deep cerebellar nuclei neurons in young mice; aged TMEM106B-deficient mice show loss of Purkinje neurons in the anterior cerebellar lobe; TMEM106B deficiency causes distinct cell-type-specific lysosomal phenotypes.\",\n      \"method\": \"Tmem106b-/- mouse model, immunofluorescence, electron microscopy, synapse quantification, behavioral analysis\",\n      \"journal\": \"Acta neuropathologica communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO mouse with multiple defined cellular readouts\",\n      \"pmids\": [\"35287730\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TMEM106B serves as an ACE2-independent receptor for SARS-CoV-2 entry: the luminal domain (LD) of TMEM106B directly engages the receptor-binding motif of SARS-CoV-2 spike protein; spike substitution E484D enhances TMEM106B binding and TMEM106B-mediated entry; TMEM106B-specific monoclonal antibodies block SARS-CoV-2 infection; TMEM106B promotes spike-mediated syncytium formation, suggesting a role in viral membrane fusion.\",\n      \"method\": \"X-ray crystallography and cryo-EM of TMEM106B LD–spike complex, HDX-MS, monoclonal antibody blocking assays, pseudovirus entry in ACE2-negative cells, syncytium formation assay\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — atomic structures by multiple methods, mutagenesis, and antibody functional validation\",\n      \"pmids\": [\"37421949\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TMEM106B deficiency in mice reduces microglia proliferation and activation, increases microglial apoptosis in response to demyelination, increases lysosomal pH and decreases lysosomal enzyme activities in microglia, and significantly decreases TREM2 protein levels; microglial-specific ablation of TMEM106B produces similar phenotypes and myelination defects.\",\n      \"method\": \"Tmem106b-/- mouse, microglial-specific conditional KO mouse, lysosomal pH assay, TREM2 western blot, immunohistochemistry for microglia markers, demyelination challenge\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — global and cell-type-specific KO with multiple defined mechanistic readouts\",\n      \"pmids\": [\"37146150\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TMEM106B physically interacts with galactosylceramidase (co-immunoprecipitation); TMEM106B deficiency significantly increases galactosylceramidase activity and decreases levels of galactosylceramide and sulfatide (major myelin lipids) in mouse brain, indicating that TMEM106B regulates myelin lipid metabolism through interaction with galactosylceramidase.\",\n      \"method\": \"Lipidomic analysis of Tmem106b-/- mouse brain, co-immunoprecipitation of TMEM106B and galactosylceramidase, galactosylceramidase enzyme activity assay\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP identifying binding partner validated by enzyme activity and lipidomics\",\n      \"pmids\": [\"39237682\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Lysosomal cysteine-type proteases perform the initial cleavage of TMEM106B's luminal domain (generating the C-terminal fragment capable of fibril formation) and also perform additional C-terminal trimming; this shedding occurs physiologically and is detectable in cellular and mouse models.\",\n      \"method\": \"Antibody development against luminal domain, pharmacological inhibition of specific protease classes, cellular and TMEM106B-related mouse models, human autopsy tissue immunoblotting\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — protease class identified with pharmacological inhibitors, multiple model systems\",\n      \"pmids\": [\"39709600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TMEM106B deletion in a P301S tau mouse model accelerates cognitive decline, hind limb paralysis, tau pathology, and neurodegeneration; the T185S coding variant (knock-in) protects against tau-associated cognitive decline, synaptic impairment, neurodegeneration, and paralysis without affecting tau pathology itself, demonstrating that TMEM106B acts downstream of tau aggregation to preserve neuronal function.\",\n      \"method\": \"Tmem106b-/- and T186S knock-in mice crossed with P301S tau transgenic mice, behavioral testing, tau pathology quantification, synaptic protein analysis, transcriptomics\",\n      \"journal\": \"Acta neuropathologica\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — both KO and knock-in (coding variant) crossed with disease model, multiple phenotypic readouts\",\n      \"pmids\": [\"38526616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TMEM106B C-terminal fragment core accumulation in FTLD-TDP postmortem brain is associated with TDP-43 dysfunction; carriers of the risk genotype (rs3173615) show higher TMEM106B core deposition, while protective allele carriers show minimal core deposition and an increase in dimeric full-length TMEM106B; interactome data implicate TMEM106B core filaments in impaired RNA transport, local translation, and endolysosomal function.\",\n      \"method\": \"Novel antibody targeting TMEM106B filament core, immunoblotting of postmortem FTLD-TDP samples stratified by rs3173615 genotype, interactome proteomics\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct measurement in human tissue with genotype stratification and proteomics, single study\",\n      \"pmids\": [\"38232138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TMEM106B loss in Tmem106b-/- PS19 (P301S tau) mice enhances accumulation of pathological tau in neuronal soma in the hippocampus, causes severe neuronal loss, and exacerbates abnormalities in neuronal cytoskeleton, autophagy-lysosome activities, and glial activation compared to PS19 alone.\",\n      \"method\": \"Tmem106b-/- × PS19 double-mutant mice, tau immunohistochemistry and pathology scoring, lysosomal/autophagy marker analysis, neuronal counting, glial activation assays\",\n      \"journal\": \"Acta neuropathologica\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean double-KO/transgenic model with multiple mechanistic readouts, replicates findings from independent concurrent study\",\n      \"pmids\": [\"38526799\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TMEM106B C-terminal fragment aggregates form amyloid inclusions (confirmed by luminescent conjugated oligothiophene staining) predominantly in astrocytes in the brain parenchyma, and also in dorsal root ganglia and spinal cord non-neuronal cells; by in situ immunoelectron microscopy, TMEM106B assemblies are found in structures resembling endosomes and lysosomes; a second cleavage beyond residue 120 is indicated by antibody staining at residues 263–274.\",\n      \"method\": \"Immunohistochemistry with TMEM106B-specific antibodies, luminescent conjugated oligothiophene (LCO) staining, transmission immuno-electron microscopy, tissue distribution analysis\",\n      \"journal\": \"Acta neuropathologica communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by immunoelectron microscopy with functional implication for lysosomal origin of fibrils\",\n      \"pmids\": [\"38886865\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TMEM106B is a type II lysosomal transmembrane protein whose luminal domain (residues 120–254) is cleaved by lysosomal cysteine proteases (and further processed by SPPL2a-mediated intramembrane proteolysis) to generate a C-terminal fragment that forms amyloid fibrils in an age-dependent manner; at the lysosomal membrane, TMEM106B regulates lysosomal acidification (through interaction with the vacuolar-ATPase), myelin lipid metabolism (through interaction with galactosylceramidase), cathepsin D levels, anterograde lysosomal transport in axons and dendrites (via MAP6 and Arl8b-dependent pathways), lysosomal exocytosis, TFEB-driven lysosomal biogenesis, microglial TREM2 levels and survival, and can also serve as an ACE2-independent receptor for SARS-CoV-2 entry through direct engagement of its luminal domain with the viral spike receptor-binding motif.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TMEM106B is a type II transmembrane protein of late endosomes and lysosomes that serves as a central regulator of lysosomal biology, controlling organelle acidification, positioning, exocytosis, and cargo degradation in neurons, glia, and other cell types. At the lysosomal membrane, TMEM106B maintains acidification through physical interaction with the vacuolar H⁺-ATPase accessory protein AP1, regulates myelin lipid metabolism via interaction with galactosylceramidase, controls anterograde lysosomal transport through MAP6- and Arl8b-dependent pathways, and promotes TFEB-driven lysosomal biogenesis and cathepsin-dependent lysosomal exocytosis [PMID:28728022, PMID:39237682, PMID:24357581, PMID:36619668, PMID:30013069]. The luminal domain (residues 120–254) undergoes sequential proteolysis—first by lysosomal cysteine proteases, then by the intramembrane protease SPPL2a—generating a C-terminal fragment that accumulates as amyloid fibrils in an age-dependent manner across neurodegenerative diseases and normal aging, with the FTLD risk variant (T185) promoting higher steady-state protein levels and greater fibril core deposition [PMID:39709600, PMID:24872421, PMID:35344985, PMID:38232138]. TMEM106B also functions as an ACE2-independent entry receptor for SARS-CoV-2, with its luminal domain directly engaging the spike receptor-binding motif to facilitate viral membrane fusion [PMID:37421949].\",\n  \"teleology\": [\n    {\n      \"year\": 2012,\n      \"claim\": \"Establishing TMEM106B as a glycosylated type II lysosomal membrane protein whose overexpression impairs endo-lysosomal acidification and degradative function resolved the basic topology and organellar context of a gene previously known only from GWAS.\",\n      \"evidence\": \"Biochemical fractionation, glycosylation-site mutagenesis, V-ATPase inhibition, overexpression with lysosomal pH and cargo degradation assays in neuronal and non-neuronal cells\",\n      \"pmids\": [\"22511793\", \"22895706\", \"23136129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No endogenous loss-of-function data yet\", \"Mechanism linking TMEM106B to V-ATPase not identified\", \"Relevance to human disease beyond GWAS association unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identifying MAP6 as a physical interactor and demonstrating that TMEM106B controls dendritic lysosomal transport revealed a direct mechanistic link between TMEM106B and neuronal morphology, explaining how lysosomal positioning defects translate to dendritic arborization phenotypes.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation of TMEM106B–MAP6, live lysosomal transport imaging, and MAP6/RILP epistasis rescue in primary neurons\",\n      \"pmids\": [\"24357581\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MAP6 interaction is direct or bridged remains unclear\", \"Axonal transport effects not yet tested\", \"No structural basis for the interaction\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Discovery that TMEM106B undergoes regulated intramembrane proteolysis—first by lysosomal proteases, then by SPPL2a—identified a processing pathway that would later prove critical for understanding amyloid fibril generation from the cleaved C-terminal fragment.\",\n      \"evidence\": \"Cell-based cleavage assays with pharmacological inhibitors and SPPL2a/2b overexpression, domain-deletion mutagenesis\",\n      \"pmids\": [\"24872421\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the initial lysosomal protease unresolved\", \"Physiological triggers for cleavage unknown\", \"Fate and function of the released intracellular domain unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrating that TMEM106B physically binds the V-ATPase AP1 subunit and that Tmem106b deletion rescues lysosomal and behavioral defects of Grn−/− mice mechanistically connected TMEM106B to lysosomal acidification and established its genetic interaction with progranulin in vivo.\",\n      \"evidence\": \"Co-immunoprecipitation of TMEM106B–V-ATPase AP1, multi-omics of mouse brain, behavioral rescue in Grn−/−;Tmem106b−/− double-knockout mice\",\n      \"pmids\": [\"28728022\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and directness of V-ATPase interaction not resolved\", \"Whether rescue reflects restored acidification or another mechanism uncertain\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showing that TMEM106B overexpression drives TFEB-dependent lysosomal biogenesis and calcium-dependent lysosomal exocytosis of active cathepsins extended its role beyond lysosomal homeostasis to a pro-invasive function in cancer cells.\",\n      \"evidence\": \"TMEM106B overexpression in lung cancer cells with cathepsin activity assays, TFEB target analysis, calcium chelation, and in vivo metastasis models\",\n      \"pmids\": [\"30013069\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct TMEM106B–TFEB regulatory mechanism not defined\", \"Whether endogenous TMEM106B levels drive exocytosis in non-cancer contexts unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Studies in Tmem106b−/− mice demonstrated that loss of TMEM106B impairs axonal lysosomal distribution, myelination, cathepsin D levels, and lysosomal exocytosis in oligodendrocytes, establishing bidirectional dosage sensitivity and cell-type-specific functions including interaction with galactosylceramidase (later confirmed) and cathepsin D.\",\n      \"evidence\": \"Tmem106b−/− mice with live axonal transport imaging, PLP/MOG quantification, TMEM106B–cathepsin D co-immunoprecipitation, lysosomal exocytosis assays, D252N mutant characterization\",\n      \"pmids\": [\"32160553\", \"32572497\", \"36619668\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether myelination defect is cell-autonomous to oligodendrocytes vs. neuronal contribution unclear\", \"Arl8b-dependent rescue awaits in vivo validation\", \"Role of cathepsin D interaction in myelination not directly tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Three independent cryo-EM studies revealed that residues 120–254 of TMEM106B form amyloid fibrils in human brains across neurodegenerative diseases and in normal aging, fundamentally redefining TMEM106B from a lysosomal regulator to an amyloid-forming protein whose aggregation is age-dependent and disease-nonspecific.\",\n      \"evidence\": \"Cryo-EM structure determination at atomic resolution from post-mortem brain extracts of FTLD-TDP, PSP, DLB, and aged controls, with immunogold and mass spectrometry validation\",\n      \"pmids\": [\"35344985\", \"35344984\", \"35247328\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether fibril formation is pathogenic, protective, or bystander remains unknown\", \"Mechanism initiating fibril nucleation from the cleaved fragment undefined\", \"No animal model recapitulating TMEM106B amyloid formation\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Structural and functional evidence established TMEM106B as an ACE2-independent receptor for SARS-CoV-2, with its luminal domain directly engaging the spike receptor-binding motif, explaining its identification as a proviral host factor and expanding its function beyond lysosomal biology.\",\n      \"evidence\": \"X-ray crystallography and cryo-EM of TMEM106B LD–spike complex, monoclonal antibody blocking of infection, pseudovirus entry in ACE2-negative cells, syncytium formation assay\",\n      \"pmids\": [\"37421949\", \"33686287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo contribution of TMEM106B-mediated entry relative to ACE2 pathway not quantified\", \"Whether TMEM106B-mediated entry involves endosomal route exclusively is unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identification of lysosomal cysteine proteases as the enzymes performing initial luminal domain shedding, together with the finding that TMEM106B interacts with galactosylceramidase to regulate myelin lipid metabolism, completed two long-standing mechanistic gaps in TMEM106B processing and myelination pathways.\",\n      \"evidence\": \"Pharmacological inhibition of protease classes across cellular and mouse models; co-immunoprecipitation of TMEM106B–galactosylceramidase with lipidomics and enzyme activity assays in Tmem106b−/− brain\",\n      \"pmids\": [\"39709600\", \"39237682\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific cysteine protease identity (e.g., cathepsin B vs. L) not resolved\", \"Whether galactosylceramidase interaction is direct or within a larger complex unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Crossing Tmem106b−/− and T185S knock-in mice with P301S tau models demonstrated that TMEM106B loss exacerbates tau-driven neurodegeneration while the protective coding variant preserves neuronal function without affecting tau pathology, positioning TMEM106B as a downstream modifier of tauopathy outcome.\",\n      \"evidence\": \"Tmem106b−/− × PS19 and T186S knock-in × PS19 crosses with behavioral, histological, synaptic, and transcriptomic analyses\",\n      \"pmids\": [\"38526616\", \"38526799\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which T185S variant confers neuroprotection not defined\", \"Whether the effect is mediated by reduced fibril formation, improved lysosomal function, or both is unresolved\", \"Relevance to sporadic human tauopathies awaits further validation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Critical open questions include whether TMEM106B amyloid fibril formation is a cause or consequence of neurodegeneration, the identity of the specific cysteine protease(s) initiating luminal domain shedding, the structural basis of TMEM106B interactions with V-ATPase and MAP6, and how TMEM106B dosage is sensed to trigger TFEB-dependent lysosomal biogenesis.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No causal link established between TMEM106B fibrils and neurodegeneration\", \"No reconstituted in vitro system for fibril nucleation from membrane-bound TMEM106B\", \"Structural basis for most protein–protein interactions unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [15, 21]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8, 9, 14, 23]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [0, 1, 2, 7, 8, 13, 28]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0, 1, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [14, 27]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 9, 12, 13]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [8, 9, 14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [17, 18, 19, 25]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"MAP6\",\n      \"ATP6V0A1\",\n      \"CTSD\",\n      \"GALC\",\n      \"CHMP2B\",\n      \"SPPL2A\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}