{"gene":"LAPTM5","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2006,"finding":"LAPTM5 transport from the Golgi to the lysosome requires binding to the ubiquitin ligase Nedd4 via three PY motifs (L/PPxY) on LAPTM5 interacting with Nedd4 WW domains, and a LAPTM5 UIM motif that binds ubiquitinated GGA3; this trafficking is independent of LAPTM5 ubiquitination itself. Mutation of PY motifs or UIM retains LAPTM5 in the Golgi; Nedd4 or GGA3 knockdown produces the same retention.","method":"Co-immunoprecipitation, RNAi knockdown, site-directed mutagenesis of PY/UIM motifs, fluorescence microscopy/subcellular localization","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, mutagenesis of multiple motifs, RNAi knockdown, subcellular localization all in one study with clear functional readout","pmids":["17116753"],"is_preprint":false},{"year":1996,"finding":"LAPTM5 is a pentaspanning (5 transmembrane domain) integral membrane protein that localizes to lysosomes in hematopoietic cells, as determined by immunocytology and cell fractionation with a specific antibody.","method":"Immunocytology, subcellular fractionation, antibody-based detection","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct fractionation and immunocytology, single lab, two orthogonal methods","pmids":["8661146"],"is_preprint":false},{"year":2012,"finding":"LAPTM5 acts as a positive regulator of proinflammatory signaling in macrophages: LAPTM5-deficient macrophages show reduced NF-κB and MAPK activation downstream of TNF receptor and pattern recognition receptors, reduced RIP1 ubiquitination upon TNF stimulation, and up-regulated A20 (a deubiquitinase that terminates NF-κB by deubiquitinating RIP1).","method":"LAPTM5 knockdown in RAW264.7 cells, LAPTM5-/- mouse macrophages, cytokine secretion assays, NF-κB/MAPK pathway activation assays, RIP1 ubiquitination assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO mouse model plus RNAi knockdown, multiple orthogonal signaling readouts, defined pathway position at receptor-proximate RIP1 ubiquitination step","pmids":["22733818"],"is_preprint":false},{"year":2014,"finding":"LAPTM5 promotes lysosomal degradation of intracellular (newly synthesized, Golgi-localizing) CD3ζ but not of cell-surface CD3ζ in the mature TCR complex; this is independent of TCR signaling-triggered tyrosine phosphorylation of CD3ζ. LAPTM5 and the SLAP/c-Cbl pathway operate in genetically distinct pathways to downregulate TCR expression.","method":"Subcellular localization kinetics of newly synthesized CD3ζ, Golgi-targeting mutant CD3ζ, CD3ζ YF (ITAM tyrosine-to-phenylalanine) mutant, genetic epistasis with SLAP/c-Cbl","journal":"Immunology and cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis of CD3ζ combined with subcellular localization and genetic epistasis, single lab","pmids":["24638062"],"is_preprint":false},{"year":2009,"finding":"Accumulation of LAPTM5 protein in neuroblastoma cells induces non-apoptotic, caspase-independent lysosomal cell death characterized by lysosomal membrane permeabilization (LMP), interruption of autophagic flux, and accumulation of autophagic vacuoles, p62/SQSTM1, and ubiquitinated proteins.","method":"LAPTM5 restoration/overexpression in NB cells, cell death assays (non-apoptotic), autophagic flux analysis, lysosomal membrane permeabilization assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro gain-of-function with multiple orthogonal mechanistic readouts, single lab","pmids":["19787053"],"is_preprint":false},{"year":2011,"finding":"ITCH (an HECT-type E3 ubiquitin ligase) directly binds the PPxY motif of LAPTM5 via its WW domains and ubiquitinates LAPTM5, leading to its proteasomal degradation; ITCH overexpression degrades LAPTM5 and conversely ITCH knockdown stabilizes LAPTM5 protein. Inhibition of ITCH enhances LAPTM5-mediated cell death in neuroblastoma cells.","method":"Co-immunoprecipitation, ITCH overexpression and siRNA knockdown, ubiquitination assays, cell death assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, bidirectional gain/loss-of-function, ubiquitination assay, single lab","pmids":["22009753"],"is_preprint":false},{"year":2021,"finding":"LAPTM5 restricts HIV-1 infectivity in macrophages by transporting HIV-1 envelope glycoproteins to lysosomes for degradation, thereby reducing virion infectivity. HIV-1 Vpr counteracts this restriction by triggering LAPTM5 degradation via DCAF1. LAPTM5 is highly expressed in macrophages but not CD4+ T cells, explaining the macrophage-specific effect of Vpr; re-expressing LAPTM5 in CD4+ T cells reconstitutes Vpr-dependent enhancement of infection.","method":"LAPTM5 silencing/reconstitution, Vpr expression, HIV-1 infection assays in macrophages and CD4+ T cells, envelope glycoprotein trafficking assays, DCAF1-dependent degradation assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal experiments including silencing phenocopy, reconstitution in T cells, mechanism through DCAF1, and envelope trafficking to lysosomes","pmids":["34140527"],"is_preprint":false},{"year":2022,"finding":"BCR stimulation up-regulates LAPTM5, which then triggers immature B cell apoptosis via two mechanisms: (1) promoting BCR internalization and reducing SYK and ERK phosphorylation; (2) targeting the E3 ubiquitin ligase WWP2 for lysosomal degradation, causing accumulation of its substrate PTEN, suppressing AKT phosphorylation, increasing FOXO1/p27Kip1/BIM expression. In vivo, LAPTM5 deficiency exacerbates autoreactive B cell survival and autoantibody production.","method":"BCR stimulation assays, LAPTM5 overexpression/knockout, BCR internalization assays, phospho-SYK/ERK/AKT measurement, WWP2/PTEN protein level assays, LAPTM5-/- mice","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (internalization, signaling pathway, lysosomal degradation of WWP2, KO mice), two mechanistically distinct arms defined in one study","pmids":["36037365"],"is_preprint":false},{"year":2022,"finding":"hnRNP K binds to and stabilizes LAPTM5 mRNA, and this is regulated upstream by the lncRNA LCDR; knockdown of hnRNP K destabilizes LAPTM5 transcript, reduces LAPTM5 protein, and promotes lysosomal membrane permeabilization and cell death. LAPTM5 overexpression or cathepsin B inhibition partially rescues LMP induced by LCDR/hnRNP K knockdown.","method":"RNA-protein binding assays, siRNA knockdown of hnRNP K and LAPTM5, LAPTM5 mRNA stability assays, lysosomal membrane permeabilization assays, rescue experiments in vitro and in vivo (PDX)","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNA-protein binding, knockdown, rescue experiments, multiple readouts, single lab","pmids":["35091468"],"is_preprint":false},{"year":2012,"finding":"LAPTM5 physically associates with CD1e (a lipid antigen presentation protein) in trans-Golgi and late endosomal compartments; the interaction is detectable under physiological conditions and is enhanced when lysosomal acidification is blocked by bafilomycin. However, LAPTM5 does not control CD1e ubiquitination or the generation of soluble lysosomal CD1e.","method":"Co-immunoprecipitation, co-localization by fluorescence microscopy, bafilomycin treatment","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and co-localization confirmed under physiological conditions, negative result for ubiquitination control adds rigor, single lab","pmids":["22880058"],"is_preprint":false},{"year":2017,"finding":"Ectopic overexpression of LAPTM5 in HeLa cells causes lysosomal targeting of LAPTM5, down-regulation of Mcl-1 and Bid, Bak activation, mitochondrial membrane potential loss, and caspase-9/-8/-3-dependent apoptosis; cathepsin inhibition (but not pan-caspase inhibition) blocks LAPTM5-induced mitochondrial depolarization, indicating a cathepsin-dependent lysosomal pathway upstream of mitochondria.","method":"GFP-LAPTM5 overexpression in HeLa cells, flow cytometry (apoptosis, ΔΨm), caspase activity assays, cathepsin inhibitor and pan-caspase inhibitor rescue experiments, Mcl-1 co-overexpression rescue","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological inhibitor dissection, rescue by Mcl-1 co-expression, multiple orthogonal apoptosis readouts, single lab","pmids":["28464033"],"is_preprint":false},{"year":2019,"finding":"RUNX2 directly transactivates the LAPTM5 gene by binding the LAPTM5 promoter at position -1176 to -1171 (confirmed by ChIP and dual-luciferase reporter assay). LAPTM5 in turn is involved in trafficking of RANKL: LAPTM5 knockdown increases RANKL protein in cytoplasm and culture media and enhances osteoclastic differentiation of co-cultured cells.","method":"ChIP, dual-luciferase reporter assay, RUNX2 overexpression/silencing, LAPTM5 knockdown, RANKL ELISA/quantification, osteoclast differentiation co-culture assay","journal":"Molecular medicine reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus reporter assay confirms direct transcriptional regulation; RANKL trafficking shown by knockdown and co-culture, single lab","pmids":["31545469"],"is_preprint":false},{"year":2020,"finding":"LAPTM5 suppresses CD40-mediated NF-κB activation in glioblastoma cells; LAPTM5 knockdown unleashes CD40-driven NF-κB signaling, increasing invasiveness, clonogenicity, and temozolomide resistance, all of which are reversed by NF-κB inhibition.","method":"LAPTM5 knockdown in glioma cell lines, expression array, NF-κB inhibition rescue, invasion/clonogenicity/chemosensitivity assays in vitro and in vivo","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with pathway rescue by NF-κB inhibitor, defined epistasis between LAPTM5 and CD40/NF-κB, single lab","pmids":["32582531"],"is_preprint":false},{"year":2025,"finding":"LAPTM5 competes with LAMP1 for binding to the E3 ubiquitin ligase WWP2, thereby inhibiting LAMP1 ubiquitination and degradation, preserving lysosomal membrane stability and autophagic flux, and conferring cisplatin resistance in NSCLC. LAPTM5 knockdown increases lysosomal membrane permeability, releases cathepsin D, elevates ROS, and accelerates cell death.","method":"Co-immunoprecipitation (LAPTM5-WWP2-LAMP1 interactions), LAPTM5 knockdown, lysosomal membrane permeability assays, cathepsin D release, ROS measurement, cell viability assays","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP defining competitive binding, loss-of-function with multiple downstream readouts, single lab","pmids":["40280227"],"is_preprint":false},{"year":2025,"finding":"LAPTM5 associates with STING and represses both K48- and K63-linked polyubiquitination of STING, preventing its proteasomal and lysosomal degradation and thereby stabilizing STING protein levels; LAPTM5 knockdown reduces STING protein, its downstream signaling (including inflammatory responses), and alleviates LL-37-induced rosacea-like phenotypes in mice.","method":"Co-immunoprecipitation (LAPTM5-STING), LAPTM5 knockdown in macrophages, ubiquitination assays (K48/K63-linkage specific), STING protein stability assays, in vivo LL-37 rosacea model","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, linkage-specific ubiquitination assays, in vitro and in vivo loss-of-function, single lab","pmids":["41087666"],"is_preprint":false},{"year":2026,"finding":"Ginkgetin (GK) inhibits K48-linked ubiquitination of Laptm5 at sites K86 and K122 (identified by site mutation assays) by targeting Ube3c (identified by biotin pulldown and DARTS), stabilizing Laptm5 protein. Increased Laptm5 promotes autophagosome-lysosome fusion and autophagy-mediated degradation of TBK1, reducing downstream inflammatory signaling in macrophages.","method":"Co-immunoprecipitation, site mutation of Laptm5 (K86, K122), biotin pulldown with mass spectrometry, DARTS, ubiquitination assays, autophagic flux assays, TBK1 degradation assays","journal":"Phytomedicine","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — site-directed mutagenesis of ubiquitination sites, target identification by pulldown/MS/DARTS, multiple mechanistic assays, single lab","pmids":["41666511"],"is_preprint":false},{"year":2026,"finding":"LAPTM5 promotes renal tubular epithelial cell EMT and fibrosis by interacting with USP10 and facilitating its lysosomal degradation, thereby reducing PTEN levels and relieving PTEN-mediated inhibition of the PI3K/AKT/mTOR-autophagy pathway. PTEN overexpression rescues LAPTM5-induced EMT.","method":"Co-immunoprecipitation (LAPTM5-USP10), LAPTM5 overexpression, PTEN rescue experiments, D-galactose progeroid mouse model, Western blot for pathway components","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP defines interaction, rescue by PTEN overexpression places LAPTM5 in pathway, in vivo validation, single lab","pmids":["42149696"],"is_preprint":false},{"year":2023,"finding":"c-Myc transcriptionally represses LAPTM5 by binding to two E-boxes in the LAPTM5 promoter. Additionally, Myc transactivates miR-17-3p, which binds 11 sites in the LAPTM5 3'UTR to inhibit LAPTM5 protein synthesis, providing a dual transcriptional and post-transcriptional suppression mechanism.","method":"Promoter binding assays (E-box mutagenesis implied), miRNA-target site analysis with 3'UTR reporter, B-lymphoma growth assays with CDS vs CDS+3'UTR constructs","journal":"Annals of hematology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — abstract does not clearly describe ChIP or direct mutagenesis of promoter E-boxes; miR-17-3p interaction inferred from 3'UTR construct; single lab, limited methodological detail in abstract","pmids":["37713124"],"is_preprint":false},{"year":2023,"finding":"FOXP3 directly binds the LAPTM5 promoter and negatively regulates LAPTM5 expression, as confirmed by dual-luciferase reporter and chromatin immunoprecipitation assays. LAPTM5 promotes breast cancer malignant phenotypes (proliferation, migration, invasion, EMT) partly through activation of the Wnt/β-catenin signaling pathway.","method":"ChIP, dual-luciferase reporter assay, LAPTM5 overexpression/knockdown, Wnt/β-catenin pathway analysis, xenograft tumor assay","journal":"Oncology reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and reporter assay confirm direct transcriptional regulation, in vitro and in vivo functional assays, single lab","pmids":["36799186"],"is_preprint":false},{"year":2025,"finding":"WDFY4 interacts with LAPTM5 (validated by co-immunoprecipitation and immunofluorescence co-localization), and WDFY4 knockdown inhibits LAPTM5 expression; elevated LAPTM5 activates the downstream CDC42/mTOR/4EBP1/SLC7A11 pathway, promoting ferroptosis and inflammation in endothelial cells. LAPTM5 overexpression rescues the anti-ferroptotic effect of WDFY4 knockdown.","method":"Co-immunoprecipitation, immunofluorescence co-localization, WDFY4 knockdown, LAPTM5 overexpression rescue, pathway analysis (CDC42/mTOR/4EBP1/SLC7A11), in vivo ApoE-/- mouse model","journal":"Journal of cellular and molecular medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-IP confirms interaction, pathway placement by knockdown/rescue, but single lab and pathway below LAPTM5 not directly mechanistically elaborated","pmids":["40755163"],"is_preprint":false},{"year":2023,"finding":"ZKSCAN5 and SETD7 both bind the LAPTM5 promoter and form a complex; ZKSCAN5 recruits SETD7 to promote LAPTM5 transcription in pancreatic ductal adenocarcinoma cells. LAPTM5 knockdown reverses the pro-metastatic effect of ZKSCAN5 overexpression.","method":"ChIP (ZKSCAN5 and SETD7 binding to LAPTM5 promoter), co-immunoprecipitation (ZKSCAN5-SETD7 complex), LAPTM5 knockdown rescue of ZKSCAN5-driven metastasis, in vivo liver metastasis model","journal":"Histology and histopathology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — ChIP and co-IP described but single lab with limited orthogonal validation in abstract","pmids":["38018874"],"is_preprint":false},{"year":2026,"finding":"In AML, LAPTM5 promotes autophagic flux by upregulating LAMP1 and LAMP2 expression, facilitating autophagolysosome formation; LAPTM5 knockdown impairs lysosomal biogenesis and disrupts autophagolysosome formation, sensitizing resistant AML cells to cytarabine.","method":"LAPTM5 knockdown, autophagic flux assays, LAMP1/LAMP2 expression analysis, in vivo tumor growth assays with cytarabine combination","journal":"Cell death & disease","confidence":"Low","confidence_rationale":"Tier 3 / Weak — loss-of-function with autophagic flux readout, no direct mechanistic link (e.g., promoter assay) between LAPTM5 and LAMP1/2 transcription established in abstract","pmids":["41912486"],"is_preprint":false}],"current_model":"LAPTM5 is a five-transmembrane-domain lysosomal protein preferentially expressed in hematopoietic/immune cells that uses its PY motifs to recruit Nedd4 and its UIM to bind ubiquitinated GGA3, enabling Golgi-to-lysosome trafficking of itself and cargo proteins (e.g., CD3ζ, BCR components, envelope glycoproteins, WWP2, USP10, RANKL) for degradation; it acts as a positive modulator of proinflammatory NF-κB/MAPK signaling in macrophages (by sustaining RIP1 ubiquitination and suppressing A20), a negative regulator of lymphocyte activation (by promoting lysosomal degradation of TCR and BCR components and the E3 ligase WWP2, leading to PTEN accumulation and AKT suppression), and a stabilizer of STING (by inhibiting its ubiquitination and degradation); its own protein levels are controlled by ITCH-mediated ubiquitination/degradation, and its gene is transcriptionally regulated by RUNX2, FOXP3, and c-Myc, with excessive LAPTM5 accumulation triggering lysosomal membrane permeabilization and caspase-independent cell death."},"narrative":{"mechanistic_narrative":"LAPTM5 is a pentaspanning lysosomal integral membrane protein of hematopoietic cells that governs lysosomal trafficking and degradation of selected cargo, thereby tuning immune receptor signaling and lysosomal homeostasis [PMID:8661146, PMID:36037365]. Its own Golgi-to-lysosome delivery requires three PY motifs that recruit the Nedd4 ubiquitin ligase through WW-domain contacts and a UIM that engages ubiquitinated GGA3, a route that operates independently of LAPTM5 ubiquitination itself [PMID:17116753]. Through this lysosomal sorting machinery LAPTM5 drives degradation of intracellular cargo including newly synthesized CD3ζ [PMID:24638062], the E3 ligase WWP2 [PMID:36037365], the deubiquitinase USP10 [PMID:42149696], and HIV-1 envelope glycoproteins, the last restricting macrophage HIV-1 infectivity until antagonized by Vpr acting via DCAF1 [PMID:34140527]. In lymphocytes LAPTM5 is a negative regulator of activation: BCR engagement upregulates LAPTM5, which promotes BCR internalization and degrades WWP2 to cause PTEN accumulation and AKT suppression, restraining autoreactive B cells [PMID:36037365], a PTEN/PI3K-AKT-mTOR axis it also engages via USP10 in renal epithelial fibrosis [PMID:42149696]. In macrophages LAPTM5 positively sustains proinflammatory NF-κB and MAPK signaling by maintaining RIP1 ubiquitination and limiting A20 [PMID:22733818], and it stabilizes STING by blocking both K48- and K63-linked polyubiquitination [PMID:41087666]. LAPTM5 protein abundance is itself set by ubiquitin ligases—ITCH binds its PPxY motif and targets it for proteasomal degradation [PMID:22009753]—and its accumulation can trigger lysosomal membrane permeabilization and cathepsin-dependent, caspase-independent or apoptotic cell death [PMID:19787053, PMID:28464033]. Its expression is transcriptionally controlled by activators including RUNX2 [PMID:31545469] and repressors including FOXP3 [PMID:36799186]. LAPTM5 additionally preserves lysosomal membrane stability and autophagic flux, in part by competing with LAMP1 for WWP2 binding to block LAMP1 degradation [PMID:40280227].","teleology":[{"year":1996,"claim":"Establishing LAPTM5 as a multispanning lysosomal membrane protein of hematopoietic cells defined the organelle and cell types where it acts.","evidence":"Immunocytology and subcellular fractionation with a specific antibody","pmids":["8661146"],"confidence":"Medium","gaps":["No molecular function assigned at this stage","Trafficking route to lysosome not yet defined"]},{"year":2006,"claim":"Defining the trafficking code resolved how LAPTM5 reaches the lysosome, showing it depends on PY-motif recruitment of Nedd4 and UIM binding of ubiquitinated GGA3 rather than on its own ubiquitination.","evidence":"Co-IP, RNAi knockdown of Nedd4/GGA3, and site-directed mutagenesis of PY/UIM motifs with subcellular localization","pmids":["17116753"],"confidence":"High","gaps":["Cargo carried along this route not yet identified","Structural basis of UIM-GGA3 recognition not resolved"]},{"year":2009,"claim":"Linking LAPTM5 accumulation to lysosomal membrane permeabilization established that excess protein is cytotoxic through a non-apoptotic lysosomal death program.","evidence":"LAPTM5 restoration in neuroblastoma cells with autophagic flux and LMP assays","pmids":["19787053"],"confidence":"Medium","gaps":["Molecular trigger of LMP unknown","Relationship to physiological LAPTM5 levels unclear"]},{"year":2011,"claim":"Identifying ITCH as a ligase for LAPTM5 explained how its abundance is restrained post-translationally and how this controls its cytotoxicity.","evidence":"Co-IP, bidirectional ITCH gain/loss-of-function, ubiquitination and cell death assays","pmids":["22009753"],"confidence":"Medium","gaps":["Single lab","Ubiquitination site on LAPTM5 not mapped in this study"]},{"year":2012,"claim":"Genetic dissection placed LAPTM5 as a positive regulator of macrophage proinflammatory signaling acting at the RIP1 ubiquitination/A20 step.","evidence":"LAPTM5-/- macrophages and RAW264.7 knockdown with NF-κB/MAPK and RIP1 ubiquitination readouts","pmids":["22733818"],"confidence":"High","gaps":["Direct biochemical mechanism linking lysosomal LAPTM5 to RIP1/A20 unclear","Whether effect requires cargo degradation untested"]},{"year":2014,"claim":"Showing LAPTM5 degrades intracellular but not surface CD3ζ defined cargo selectivity and separated it from the SLAP/c-Cbl downregulation pathway.","evidence":"Localization kinetics of newly synthesized CD3ζ, Golgi-targeting and ITAM mutants, genetic epistasis","pmids":["24638062"],"confidence":"Medium","gaps":["Direct LAPTM5-CD3ζ binding interface not defined","Single lab"]},{"year":2021,"claim":"Demonstrating LAPTM5-mediated lysosomal degradation of HIV-1 envelope glycoproteins identified an antiviral restriction function and its Vpr/DCAF1 antagonism, explaining macrophage-specific Vpr effects.","evidence":"Silencing/reconstitution, Vpr expression, HIV-1 infection and envelope trafficking assays in macrophages and CD4+ T cells","pmids":["34140527"],"confidence":"High","gaps":["Whether envelope is direct LAPTM5 cargo not biochemically resolved","Breadth across other enveloped viruses untested"]},{"year":2022,"claim":"Mechanistic work in immature B cells defined a dual pathway by which LAPTM5 restrains lymphocyte activation: BCR internalization plus WWP2 degradation leading to PTEN/AKT suppression.","evidence":"BCR stimulation, LAPTM5 overexpression/KO, internalization and phospho-signaling assays, WWP2/PTEN measurement, LAPTM5-/- mice","pmids":["36037365"],"confidence":"High","gaps":["How LAPTM5 selects WWP2 for degradation not detailed","Relative contribution of the two arms in vivo unquantified"]},{"year":2022,"claim":"Identifying hnRNP K/LCDR-mediated stabilization of LAPTM5 mRNA added a post-transcriptional control layer tying LAPTM5 levels to lysosomal stability.","evidence":"RNA-protein binding, knockdown, mRNA stability and LMP assays, rescue in vitro and PDX","pmids":["35091468"],"confidence":"Medium","gaps":["Direct hnRNP K binding site on LAPTM5 mRNA not mapped","Single lab"]},{"year":2023,"claim":"Multiple studies positioned LAPTM5 within transcriptional circuits, identifying FOXP3 as a direct repressor and Myc as a dual transcriptional/post-transcriptional suppressor.","evidence":"ChIP and dual-luciferase reporter assays (FOXP3); promoter E-box and 3'UTR reporter analysis (Myc/miR-17-3p)","pmids":["36799186","37713124"],"confidence":"Medium","gaps":["Myc/miR-17-3p regulation rests on limited methodological detail","Tissue specificity of these regulators not integrated"]},{"year":2025,"claim":"Two studies extended LAPTM5 to ubiquitin-balance control of partner proteins: stabilizing STING by blocking its polyubiquitination, and preserving LAMP1 by competing with WWP2.","evidence":"Co-IP, linkage-specific ubiquitination assays, knockdown with downstream readouts, in vivo rosacea and NSCLC models","pmids":["41087666","40280227"],"confidence":"Medium","gaps":["Whether STING stabilization is direct or via cargo trafficking unclear","Structural basis of LAPTM5-WWP2-LAMP1 competition unresolved"]},{"year":2026,"claim":"Further work mapped ubiquitination sites K86/K122 controlling LAPTM5 stability via Ube3c and linked LAPTM5 to autophagy-mediated TBK1 degradation and to USP10/PTEN-driven fibrosis.","evidence":"Site-directed mutagenesis, biotin pulldown/MS/DARTS, autophagic flux and TBK1 assays; co-IP and PTEN rescue in a progeroid model","pmids":["41666511","42149696"],"confidence":"Medium","gaps":["Single lab for each finding","Integration of ubiquitination-site control with Nedd4/ITCH inputs not established"]},{"year":null,"claim":"A unifying biochemical mechanism explaining how one lysosomal trafficking protein can both promote and suppress signaling in a cell-type- and cargo-specific manner remains undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of cargo recognition","Rules determining which cargo are degraded vs which partners are stabilized unknown","How LAPTM5 mechanistically modulates RIP1/A20 and STING ubiquitination not resolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[3,7,16,6]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[2,7]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[1]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[1,0]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[9]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,7,6]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[4,13]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,3]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,7,14]}],"complexes":[],"partners":["NEDD4","GGA3","ITCH","WWP2","STING1","USP10","CD1E","WDFY4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q13571","full_name":"Lysosomal-associated transmembrane protein 5","aliases":["Lysosomal-associated multitransmembrane protein 5","Retinoic acid-inducible E3 protein"],"length_aa":262,"mass_kda":29.9,"function":"May have a special functional role during embryogenesis and in adult hematopoietic cells","subcellular_location":"Lysosome membrane","url":"https://www.uniprot.org/uniprotkb/Q13571/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LAPTM5","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/LAPTM5","total_profiled":1310},"omim":[{"mim_id":"608323","title":"CHARCOT-MARIE-TOOTH DISEASE, DOMINANT INTERMEDIATE C; CMTDIC","url":"https://www.omim.org/entry/608323"},{"mim_id":"601476","title":"LYSOSOME-ASSOCIATED PROTEIN, TRANSMEMBRANE 5; LAPTM5","url":"https://www.omim.org/entry/601476"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"bone marrow","ntpm":1214.0},{"tissue":"lymphoid tissue","ntpm":628.3}],"url":"https://www.proteinatlas.org/search/LAPTM5"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q13571","domains":[{"cath_id":"-","chopping":"9-45_61-163_180-229","consensus_level":"high","plddt":74.1996,"start":9,"end":229}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13571","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13571-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13571-F1-predicted_aligned_error_v6.png","plddt_mean":69.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LAPTM5","jax_strain_url":"https://www.jax.org/strain/search?query=LAPTM5"},"sequence":{"accession":"Q13571","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13571.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13571/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13571"}},"corpus_meta":[{"pmid":"17116753","id":"PMC_17116753","title":"Transport of LAPTM5 to lysosomes requires association with the ubiquitin ligase Nedd4, but not LAPTM5 ubiquitination.","date":"2006","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/17116753","citation_count":87,"is_preprint":false},{"pmid":"8661146","id":"PMC_8661146","title":"LAPTM5: a novel lysosomal-associated multispanning membrane protein preferentially expressed in hematopoietic cells.","date":"1996","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8661146","citation_count":81,"is_preprint":false},{"pmid":"36037300","id":"PMC_36037300","title":"Genome-Scale CRISPR screen identifies LAPTM5 driving lenvatinib resistance in hepatocellular carcinoma.","date":"2022","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/36037300","citation_count":80,"is_preprint":false},{"pmid":"22733818","id":"PMC_22733818","title":"LAPTM5 protein is a positive regulator of proinflammatory signaling pathways in macrophages.","date":"2012","source":"The Journal of biological 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Gliomas","date":"2024-12-30","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.29.630486","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":22723,"output_tokens":6323,"usd":0.081507,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15125,"output_tokens":4228,"usd":0.090662,"stage2_stop_reason":"end_turn"},"total_usd":0.172169,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"LAPTM5 transport from the Golgi to the lysosome requires binding to the ubiquitin ligase Nedd4 via three PY motifs (L/PPxY) on LAPTM5 interacting with Nedd4 WW domains, and a LAPTM5 UIM motif that binds ubiquitinated GGA3; this trafficking is independent of LAPTM5 ubiquitination itself. Mutation of PY motifs or UIM retains LAPTM5 in the Golgi; Nedd4 or GGA3 knockdown produces the same retention.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, site-directed mutagenesis of PY/UIM motifs, fluorescence microscopy/subcellular localization\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, mutagenesis of multiple motifs, RNAi knockdown, subcellular localization all in one study with clear functional readout\",\n      \"pmids\": [\"17116753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"LAPTM5 is a pentaspanning (5 transmembrane domain) integral membrane protein that localizes to lysosomes in hematopoietic cells, as determined by immunocytology and cell fractionation with a specific antibody.\",\n      \"method\": \"Immunocytology, subcellular fractionation, antibody-based detection\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct fractionation and immunocytology, single lab, two orthogonal methods\",\n      \"pmids\": [\"8661146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LAPTM5 acts as a positive regulator of proinflammatory signaling in macrophages: LAPTM5-deficient macrophages show reduced NF-κB and MAPK activation downstream of TNF receptor and pattern recognition receptors, reduced RIP1 ubiquitination upon TNF stimulation, and up-regulated A20 (a deubiquitinase that terminates NF-κB by deubiquitinating RIP1).\",\n      \"method\": \"LAPTM5 knockdown in RAW264.7 cells, LAPTM5-/- mouse macrophages, cytokine secretion assays, NF-κB/MAPK pathway activation assays, RIP1 ubiquitination assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO mouse model plus RNAi knockdown, multiple orthogonal signaling readouts, defined pathway position at receptor-proximate RIP1 ubiquitination step\",\n      \"pmids\": [\"22733818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LAPTM5 promotes lysosomal degradation of intracellular (newly synthesized, Golgi-localizing) CD3ζ but not of cell-surface CD3ζ in the mature TCR complex; this is independent of TCR signaling-triggered tyrosine phosphorylation of CD3ζ. LAPTM5 and the SLAP/c-Cbl pathway operate in genetically distinct pathways to downregulate TCR expression.\",\n      \"method\": \"Subcellular localization kinetics of newly synthesized CD3ζ, Golgi-targeting mutant CD3ζ, CD3ζ YF (ITAM tyrosine-to-phenylalanine) mutant, genetic epistasis with SLAP/c-Cbl\",\n      \"journal\": \"Immunology and cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis of CD3ζ combined with subcellular localization and genetic epistasis, single lab\",\n      \"pmids\": [\"24638062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Accumulation of LAPTM5 protein in neuroblastoma cells induces non-apoptotic, caspase-independent lysosomal cell death characterized by lysosomal membrane permeabilization (LMP), interruption of autophagic flux, and accumulation of autophagic vacuoles, p62/SQSTM1, and ubiquitinated proteins.\",\n      \"method\": \"LAPTM5 restoration/overexpression in NB cells, cell death assays (non-apoptotic), autophagic flux analysis, lysosomal membrane permeabilization assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro gain-of-function with multiple orthogonal mechanistic readouts, single lab\",\n      \"pmids\": [\"19787053\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ITCH (an HECT-type E3 ubiquitin ligase) directly binds the PPxY motif of LAPTM5 via its WW domains and ubiquitinates LAPTM5, leading to its proteasomal degradation; ITCH overexpression degrades LAPTM5 and conversely ITCH knockdown stabilizes LAPTM5 protein. Inhibition of ITCH enhances LAPTM5-mediated cell death in neuroblastoma cells.\",\n      \"method\": \"Co-immunoprecipitation, ITCH overexpression and siRNA knockdown, ubiquitination assays, cell death assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, bidirectional gain/loss-of-function, ubiquitination assay, single lab\",\n      \"pmids\": [\"22009753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LAPTM5 restricts HIV-1 infectivity in macrophages by transporting HIV-1 envelope glycoproteins to lysosomes for degradation, thereby reducing virion infectivity. HIV-1 Vpr counteracts this restriction by triggering LAPTM5 degradation via DCAF1. LAPTM5 is highly expressed in macrophages but not CD4+ T cells, explaining the macrophage-specific effect of Vpr; re-expressing LAPTM5 in CD4+ T cells reconstitutes Vpr-dependent enhancement of infection.\",\n      \"method\": \"LAPTM5 silencing/reconstitution, Vpr expression, HIV-1 infection assays in macrophages and CD4+ T cells, envelope glycoprotein trafficking assays, DCAF1-dependent degradation assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal experiments including silencing phenocopy, reconstitution in T cells, mechanism through DCAF1, and envelope trafficking to lysosomes\",\n      \"pmids\": [\"34140527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"BCR stimulation up-regulates LAPTM5, which then triggers immature B cell apoptosis via two mechanisms: (1) promoting BCR internalization and reducing SYK and ERK phosphorylation; (2) targeting the E3 ubiquitin ligase WWP2 for lysosomal degradation, causing accumulation of its substrate PTEN, suppressing AKT phosphorylation, increasing FOXO1/p27Kip1/BIM expression. In vivo, LAPTM5 deficiency exacerbates autoreactive B cell survival and autoantibody production.\",\n      \"method\": \"BCR stimulation assays, LAPTM5 overexpression/knockout, BCR internalization assays, phospho-SYK/ERK/AKT measurement, WWP2/PTEN protein level assays, LAPTM5-/- mice\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (internalization, signaling pathway, lysosomal degradation of WWP2, KO mice), two mechanistically distinct arms defined in one study\",\n      \"pmids\": [\"36037365\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"hnRNP K binds to and stabilizes LAPTM5 mRNA, and this is regulated upstream by the lncRNA LCDR; knockdown of hnRNP K destabilizes LAPTM5 transcript, reduces LAPTM5 protein, and promotes lysosomal membrane permeabilization and cell death. LAPTM5 overexpression or cathepsin B inhibition partially rescues LMP induced by LCDR/hnRNP K knockdown.\",\n      \"method\": \"RNA-protein binding assays, siRNA knockdown of hnRNP K and LAPTM5, LAPTM5 mRNA stability assays, lysosomal membrane permeabilization assays, rescue experiments in vitro and in vivo (PDX)\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNA-protein binding, knockdown, rescue experiments, multiple readouts, single lab\",\n      \"pmids\": [\"35091468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LAPTM5 physically associates with CD1e (a lipid antigen presentation protein) in trans-Golgi and late endosomal compartments; the interaction is detectable under physiological conditions and is enhanced when lysosomal acidification is blocked by bafilomycin. However, LAPTM5 does not control CD1e ubiquitination or the generation of soluble lysosomal CD1e.\",\n      \"method\": \"Co-immunoprecipitation, co-localization by fluorescence microscopy, bafilomycin treatment\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and co-localization confirmed under physiological conditions, negative result for ubiquitination control adds rigor, single lab\",\n      \"pmids\": [\"22880058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Ectopic overexpression of LAPTM5 in HeLa cells causes lysosomal targeting of LAPTM5, down-regulation of Mcl-1 and Bid, Bak activation, mitochondrial membrane potential loss, and caspase-9/-8/-3-dependent apoptosis; cathepsin inhibition (but not pan-caspase inhibition) blocks LAPTM5-induced mitochondrial depolarization, indicating a cathepsin-dependent lysosomal pathway upstream of mitochondria.\",\n      \"method\": \"GFP-LAPTM5 overexpression in HeLa cells, flow cytometry (apoptosis, ΔΨm), caspase activity assays, cathepsin inhibitor and pan-caspase inhibitor rescue experiments, Mcl-1 co-overexpression rescue\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological inhibitor dissection, rescue by Mcl-1 co-expression, multiple orthogonal apoptosis readouts, single lab\",\n      \"pmids\": [\"28464033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"RUNX2 directly transactivates the LAPTM5 gene by binding the LAPTM5 promoter at position -1176 to -1171 (confirmed by ChIP and dual-luciferase reporter assay). LAPTM5 in turn is involved in trafficking of RANKL: LAPTM5 knockdown increases RANKL protein in cytoplasm and culture media and enhances osteoclastic differentiation of co-cultured cells.\",\n      \"method\": \"ChIP, dual-luciferase reporter assay, RUNX2 overexpression/silencing, LAPTM5 knockdown, RANKL ELISA/quantification, osteoclast differentiation co-culture assay\",\n      \"journal\": \"Molecular medicine reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus reporter assay confirms direct transcriptional regulation; RANKL trafficking shown by knockdown and co-culture, single lab\",\n      \"pmids\": [\"31545469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LAPTM5 suppresses CD40-mediated NF-κB activation in glioblastoma cells; LAPTM5 knockdown unleashes CD40-driven NF-κB signaling, increasing invasiveness, clonogenicity, and temozolomide resistance, all of which are reversed by NF-κB inhibition.\",\n      \"method\": \"LAPTM5 knockdown in glioma cell lines, expression array, NF-κB inhibition rescue, invasion/clonogenicity/chemosensitivity assays in vitro and in vivo\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with pathway rescue by NF-κB inhibitor, defined epistasis between LAPTM5 and CD40/NF-κB, single lab\",\n      \"pmids\": [\"32582531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LAPTM5 competes with LAMP1 for binding to the E3 ubiquitin ligase WWP2, thereby inhibiting LAMP1 ubiquitination and degradation, preserving lysosomal membrane stability and autophagic flux, and conferring cisplatin resistance in NSCLC. LAPTM5 knockdown increases lysosomal membrane permeability, releases cathepsin D, elevates ROS, and accelerates cell death.\",\n      \"method\": \"Co-immunoprecipitation (LAPTM5-WWP2-LAMP1 interactions), LAPTM5 knockdown, lysosomal membrane permeability assays, cathepsin D release, ROS measurement, cell viability assays\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP defining competitive binding, loss-of-function with multiple downstream readouts, single lab\",\n      \"pmids\": [\"40280227\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LAPTM5 associates with STING and represses both K48- and K63-linked polyubiquitination of STING, preventing its proteasomal and lysosomal degradation and thereby stabilizing STING protein levels; LAPTM5 knockdown reduces STING protein, its downstream signaling (including inflammatory responses), and alleviates LL-37-induced rosacea-like phenotypes in mice.\",\n      \"method\": \"Co-immunoprecipitation (LAPTM5-STING), LAPTM5 knockdown in macrophages, ubiquitination assays (K48/K63-linkage specific), STING protein stability assays, in vivo LL-37 rosacea model\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, linkage-specific ubiquitination assays, in vitro and in vivo loss-of-function, single lab\",\n      \"pmids\": [\"41087666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Ginkgetin (GK) inhibits K48-linked ubiquitination of Laptm5 at sites K86 and K122 (identified by site mutation assays) by targeting Ube3c (identified by biotin pulldown and DARTS), stabilizing Laptm5 protein. Increased Laptm5 promotes autophagosome-lysosome fusion and autophagy-mediated degradation of TBK1, reducing downstream inflammatory signaling in macrophages.\",\n      \"method\": \"Co-immunoprecipitation, site mutation of Laptm5 (K86, K122), biotin pulldown with mass spectrometry, DARTS, ubiquitination assays, autophagic flux assays, TBK1 degradation assays\",\n      \"journal\": \"Phytomedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — site-directed mutagenesis of ubiquitination sites, target identification by pulldown/MS/DARTS, multiple mechanistic assays, single lab\",\n      \"pmids\": [\"41666511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"LAPTM5 promotes renal tubular epithelial cell EMT and fibrosis by interacting with USP10 and facilitating its lysosomal degradation, thereby reducing PTEN levels and relieving PTEN-mediated inhibition of the PI3K/AKT/mTOR-autophagy pathway. PTEN overexpression rescues LAPTM5-induced EMT.\",\n      \"method\": \"Co-immunoprecipitation (LAPTM5-USP10), LAPTM5 overexpression, PTEN rescue experiments, D-galactose progeroid mouse model, Western blot for pathway components\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP defines interaction, rescue by PTEN overexpression places LAPTM5 in pathway, in vivo validation, single lab\",\n      \"pmids\": [\"42149696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"c-Myc transcriptionally represses LAPTM5 by binding to two E-boxes in the LAPTM5 promoter. Additionally, Myc transactivates miR-17-3p, which binds 11 sites in the LAPTM5 3'UTR to inhibit LAPTM5 protein synthesis, providing a dual transcriptional and post-transcriptional suppression mechanism.\",\n      \"method\": \"Promoter binding assays (E-box mutagenesis implied), miRNA-target site analysis with 3'UTR reporter, B-lymphoma growth assays with CDS vs CDS+3'UTR constructs\",\n      \"journal\": \"Annals of hematology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — abstract does not clearly describe ChIP or direct mutagenesis of promoter E-boxes; miR-17-3p interaction inferred from 3'UTR construct; single lab, limited methodological detail in abstract\",\n      \"pmids\": [\"37713124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FOXP3 directly binds the LAPTM5 promoter and negatively regulates LAPTM5 expression, as confirmed by dual-luciferase reporter and chromatin immunoprecipitation assays. LAPTM5 promotes breast cancer malignant phenotypes (proliferation, migration, invasion, EMT) partly through activation of the Wnt/β-catenin signaling pathway.\",\n      \"method\": \"ChIP, dual-luciferase reporter assay, LAPTM5 overexpression/knockdown, Wnt/β-catenin pathway analysis, xenograft tumor assay\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and reporter assay confirm direct transcriptional regulation, in vitro and in vivo functional assays, single lab\",\n      \"pmids\": [\"36799186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"WDFY4 interacts with LAPTM5 (validated by co-immunoprecipitation and immunofluorescence co-localization), and WDFY4 knockdown inhibits LAPTM5 expression; elevated LAPTM5 activates the downstream CDC42/mTOR/4EBP1/SLC7A11 pathway, promoting ferroptosis and inflammation in endothelial cells. LAPTM5 overexpression rescues the anti-ferroptotic effect of WDFY4 knockdown.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, WDFY4 knockdown, LAPTM5 overexpression rescue, pathway analysis (CDC42/mTOR/4EBP1/SLC7A11), in vivo ApoE-/- mouse model\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-IP confirms interaction, pathway placement by knockdown/rescue, but single lab and pathway below LAPTM5 not directly mechanistically elaborated\",\n      \"pmids\": [\"40755163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ZKSCAN5 and SETD7 both bind the LAPTM5 promoter and form a complex; ZKSCAN5 recruits SETD7 to promote LAPTM5 transcription in pancreatic ductal adenocarcinoma cells. LAPTM5 knockdown reverses the pro-metastatic effect of ZKSCAN5 overexpression.\",\n      \"method\": \"ChIP (ZKSCAN5 and SETD7 binding to LAPTM5 promoter), co-immunoprecipitation (ZKSCAN5-SETD7 complex), LAPTM5 knockdown rescue of ZKSCAN5-driven metastasis, in vivo liver metastasis model\",\n      \"journal\": \"Histology and histopathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — ChIP and co-IP described but single lab with limited orthogonal validation in abstract\",\n      \"pmids\": [\"38018874\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In AML, LAPTM5 promotes autophagic flux by upregulating LAMP1 and LAMP2 expression, facilitating autophagolysosome formation; LAPTM5 knockdown impairs lysosomal biogenesis and disrupts autophagolysosome formation, sensitizing resistant AML cells to cytarabine.\",\n      \"method\": \"LAPTM5 knockdown, autophagic flux assays, LAMP1/LAMP2 expression analysis, in vivo tumor growth assays with cytarabine combination\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — loss-of-function with autophagic flux readout, no direct mechanistic link (e.g., promoter assay) between LAPTM5 and LAMP1/2 transcription established in abstract\",\n      \"pmids\": [\"41912486\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LAPTM5 is a five-transmembrane-domain lysosomal protein preferentially expressed in hematopoietic/immune cells that uses its PY motifs to recruit Nedd4 and its UIM to bind ubiquitinated GGA3, enabling Golgi-to-lysosome trafficking of itself and cargo proteins (e.g., CD3ζ, BCR components, envelope glycoproteins, WWP2, USP10, RANKL) for degradation; it acts as a positive modulator of proinflammatory NF-κB/MAPK signaling in macrophages (by sustaining RIP1 ubiquitination and suppressing A20), a negative regulator of lymphocyte activation (by promoting lysosomal degradation of TCR and BCR components and the E3 ligase WWP2, leading to PTEN accumulation and AKT suppression), and a stabilizer of STING (by inhibiting its ubiquitination and degradation); its own protein levels are controlled by ITCH-mediated ubiquitination/degradation, and its gene is transcriptionally regulated by RUNX2, FOXP3, and c-Myc, with excessive LAPTM5 accumulation triggering lysosomal membrane permeabilization and caspase-independent cell death.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LAPTM5 is a pentaspanning lysosomal integral membrane protein of hematopoietic cells that governs lysosomal trafficking and degradation of selected cargo, thereby tuning immune receptor signaling and lysosomal homeostasis [#1, #7]. Its own Golgi-to-lysosome delivery requires three PY motifs that recruit the Nedd4 ubiquitin ligase through WW-domain contacts and a UIM that engages ubiquitinated GGA3, a route that operates independently of LAPTM5 ubiquitination itself [#0]. Through this lysosomal sorting machinery LAPTM5 drives degradation of intracellular cargo including newly synthesized CD3\\u03b6 [#3], the E3 ligase WWP2 [#7], the deubiquitinase USP10 [#16], and HIV-1 envelope glycoproteins, the last restricting macrophage HIV-1 infectivity until antagonized by Vpr acting via DCAF1 [#6]. In lymphocytes LAPTM5 is a negative regulator of activation: BCR engagement upregulates LAPTM5, which promotes BCR internalization and degrades WWP2 to cause PTEN accumulation and AKT suppression, restraining autoreactive B cells [#7], a PTEN/PI3K-AKT-mTOR axis it also engages via USP10 in renal epithelial fibrosis [#16]. In macrophages LAPTM5 positively sustains proinflammatory NF-\\u03baB and MAPK signaling by maintaining RIP1 ubiquitination and limiting A20 [#2], and it stabilizes STING by blocking both K48- and K63-linked polyubiquitination [#14]. LAPTM5 protein abundance is itself set by ubiquitin ligases\\u2014ITCH binds its PPxY motif and targets it for proteasomal degradation [#5]\\u2014and its accumulation can trigger lysosomal membrane permeabilization and cathepsin-dependent, caspase-independent or apoptotic cell death [#4, #10]. Its expression is transcriptionally controlled by activators including RUNX2 [#11] and repressors including FOXP3 [#18]. LAPTM5 additionally preserves lysosomal membrane stability and autophagic flux, in part by competing with LAMP1 for WWP2 binding to block LAMP1 degradation [#13].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Establishing LAPTM5 as a multispanning lysosomal membrane protein of hematopoietic cells defined the organelle and cell types where it acts.\",\n      \"evidence\": \"Immunocytology and subcellular fractionation with a specific antibody\",\n      \"pmids\": [\"8661146\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular function assigned at this stage\", \"Trafficking route to lysosome not yet defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defining the trafficking code resolved how LAPTM5 reaches the lysosome, showing it depends on PY-motif recruitment of Nedd4 and UIM binding of ubiquitinated GGA3 rather than on its own ubiquitination.\",\n      \"evidence\": \"Co-IP, RNAi knockdown of Nedd4/GGA3, and site-directed mutagenesis of PY/UIM motifs with subcellular localization\",\n      \"pmids\": [\"17116753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cargo carried along this route not yet identified\", \"Structural basis of UIM-GGA3 recognition not resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Linking LAPTM5 accumulation to lysosomal membrane permeabilization established that excess protein is cytotoxic through a non-apoptotic lysosomal death program.\",\n      \"evidence\": \"LAPTM5 restoration in neuroblastoma cells with autophagic flux and LMP assays\",\n      \"pmids\": [\"19787053\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular trigger of LMP unknown\", \"Relationship to physiological LAPTM5 levels unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identifying ITCH as a ligase for LAPTM5 explained how its abundance is restrained post-translationally and how this controls its cytotoxicity.\",\n      \"evidence\": \"Co-IP, bidirectional ITCH gain/loss-of-function, ubiquitination and cell death assays\",\n      \"pmids\": [\"22009753\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Ubiquitination site on LAPTM5 not mapped in this study\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Genetic dissection placed LAPTM5 as a positive regulator of macrophage proinflammatory signaling acting at the RIP1 ubiquitination/A20 step.\",\n      \"evidence\": \"LAPTM5-/- macrophages and RAW264.7 knockdown with NF-\\u03baB/MAPK and RIP1 ubiquitination readouts\",\n      \"pmids\": [\"22733818\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical mechanism linking lysosomal LAPTM5 to RIP1/A20 unclear\", \"Whether effect requires cargo degradation untested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showing LAPTM5 degrades intracellular but not surface CD3\\u03b6 defined cargo selectivity and separated it from the SLAP/c-Cbl downregulation pathway.\",\n      \"evidence\": \"Localization kinetics of newly synthesized CD3\\u03b6, Golgi-targeting and ITAM mutants, genetic epistasis\",\n      \"pmids\": [\"24638062\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct LAPTM5-CD3\\u03b6 binding interface not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating LAPTM5-mediated lysosomal degradation of HIV-1 envelope glycoproteins identified an antiviral restriction function and its Vpr/DCAF1 antagonism, explaining macrophage-specific Vpr effects.\",\n      \"evidence\": \"Silencing/reconstitution, Vpr expression, HIV-1 infection and envelope trafficking assays in macrophages and CD4+ T cells\",\n      \"pmids\": [\"34140527\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether envelope is direct LAPTM5 cargo not biochemically resolved\", \"Breadth across other enveloped viruses untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Mechanistic work in immature B cells defined a dual pathway by which LAPTM5 restrains lymphocyte activation: BCR internalization plus WWP2 degradation leading to PTEN/AKT suppression.\",\n      \"evidence\": \"BCR stimulation, LAPTM5 overexpression/KO, internalization and phospho-signaling assays, WWP2/PTEN measurement, LAPTM5-/- mice\",\n      \"pmids\": [\"36037365\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How LAPTM5 selects WWP2 for degradation not detailed\", \"Relative contribution of the two arms in vivo unquantified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying hnRNP K/LCDR-mediated stabilization of LAPTM5 mRNA added a post-transcriptional control layer tying LAPTM5 levels to lysosomal stability.\",\n      \"evidence\": \"RNA-protein binding, knockdown, mRNA stability and LMP assays, rescue in vitro and PDX\",\n      \"pmids\": [\"35091468\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct hnRNP K binding site on LAPTM5 mRNA not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multiple studies positioned LAPTM5 within transcriptional circuits, identifying FOXP3 as a direct repressor and Myc as a dual transcriptional/post-transcriptional suppressor.\",\n      \"evidence\": \"ChIP and dual-luciferase reporter assays (FOXP3); promoter E-box and 3'UTR reporter analysis (Myc/miR-17-3p)\",\n      \"pmids\": [\"36799186\", \"37713124\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Myc/miR-17-3p regulation rests on limited methodological detail\", \"Tissue specificity of these regulators not integrated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Two studies extended LAPTM5 to ubiquitin-balance control of partner proteins: stabilizing STING by blocking its polyubiquitination, and preserving LAMP1 by competing with WWP2.\",\n      \"evidence\": \"Co-IP, linkage-specific ubiquitination assays, knockdown with downstream readouts, in vivo rosacea and NSCLC models\",\n      \"pmids\": [\"41087666\", \"40280227\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether STING stabilization is direct or via cargo trafficking unclear\", \"Structural basis of LAPTM5-WWP2-LAMP1 competition unresolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Further work mapped ubiquitination sites K86/K122 controlling LAPTM5 stability via Ube3c and linked LAPTM5 to autophagy-mediated TBK1 degradation and to USP10/PTEN-driven fibrosis.\",\n      \"evidence\": \"Site-directed mutagenesis, biotin pulldown/MS/DARTS, autophagic flux and TBK1 assays; co-IP and PTEN rescue in a progeroid model\",\n      \"pmids\": [\"41666511\", \"42149696\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab for each finding\", \"Integration of ubiquitination-site control with Nedd4/ITCH inputs not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unifying biochemical mechanism explaining how one lysosomal trafficking protein can both promote and suppress signaling in a cell-type- and cargo-specific manner remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of cargo recognition\", \"Rules determining which cargo are degraded vs which partners are stabilized unknown\", \"How LAPTM5 mechanistically modulates RIP1/A20 and STING ubiquitination not resolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 7, 16, 6]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [2, 7]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [1, 0]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 7, 6]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [4, 13]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 7, 14]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NEDD4\", \"GGA3\", \"ITCH\", \"WWP2\", \"STING1\", \"USP10\", \"CD1E\", \"WDFY4\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}