{"gene":"APLP1","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":2005,"finding":"The intracellular domain (AICD) released by presenilin-dependent γ-secretase cleavage of APLP1 (and APP/APLP2) transactivates the neprilysin gene promoter, thereby regulating neprilysin transcription, expression, and activity; this mechanism is presenilin-dependent and does not operate for Notch, N- or E-cadherin cleavage products.","method":"Transient transfection of AICD constructs, neprilysin promoter reporter assays, gamma-secretase inhibitor treatment, PS1/PS2-deficient cell lines, mouse brain activity assays","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (reporter assay, KO cells, pharmacological inhibition, in vivo brain activity), replicated across APP family members","pmids":["15944124"],"is_preprint":false},{"year":2004,"finding":"APLP1 undergoes α-, γ-, and ε-like proteolytic cleavages similar to APP; uniquely among APP family members, APLP1 processing can be modulated by N-glycosylation. p3-like fragments of APLP1 were detected in conditioned media of stably transfected cells.","method":"Stable transfection of C-terminally tagged APLP1 in SH-SY5Y cells, pharmacological protease inhibitors, detection of C-terminal fragments and secreted peptides","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based biochemical characterization with pharmacological inhibitors and tagged constructs, single lab","pmids":["14970212"],"is_preprint":false},{"year":2009,"finding":"APLP1 localizes predominantly to the cell surface, whereas APP and APLP2 are mostly found in intracellular compartments. APLP1 uniquely forms trans (intercellular) interactions in addition to cis interactions; multimerization of APLP1 depends strongly on the C-terminal half of the ectodomain rather than the N-terminal half required by APP/APLP2. Co-expression of APP with APLP1 or APLP2 reduces Aβ42 generation, attributed to formation of heteromeric complexes.","method":"Live cell imaging, FRET, co-immunoprecipitation, deletion mutant analysis in transfected cells","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus FRET plus live imaging, multiple orthogonal methods in single lab study","pmids":["19126676"],"is_preprint":false},{"year":2009,"finding":"γ-secretase processing of APLP1 produces an ~3.5 kDa p3-like peptide (ALP-1); its production is abolished by γ-secretase inhibition but not β-secretase inhibition. Unlike Aβ or p3, ALP-1 does not aggregate and is not toxic to neurons.","method":"Stable transfection of CHO cells with human APLP1, novel anti-APLP1 antibody, gamma- and beta-secretase inhibitor treatment, neurotoxicity and aggregation assays","journal":"Brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based biochemical detection with pharmacological inhibitors and orthogonal functional assays, single lab","pmids":["19401174"],"is_preprint":false},{"year":2009,"finding":"Human CSF contains three APLP1-derived Aβ-like peptides (APL1β25, APL1β27, APL1β28) generated by β- and γ-cleavages. Gamma-secretase modulators (GSMs) and familial AD presenilin1 mutants that increase Aβ42 production cause a parallel increase in APL1β28; this peptide tracks γ-secretase cleavage preference at the ε/γ site.","method":"Mass spectrometry identification of CSF peptides, cell culture treatment with GSMs and PS1 mutants, CSF analysis from PS1 mutation carriers and sporadic AD patients","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS identification plus cell-based pharmacological experiments plus human CSF validation, single lab","pmids":["20049724"],"is_preprint":false},{"year":2006,"finding":"PAT1a directly binds to APLP1 (and APP, APLP2) and co-localizes with them in trans-Golgi network vesicles or endosomes in primary neurons. PAT1a interacts with the basolateral sorting signal of APLP1/APP/APLP2; overexpression or RNAi knockdown of PAT1a modulates APLP1/APP/APLP2 levels at the cell surface and promotes their processing.","method":"Co-immunoprecipitation in vivo, co-localization in primary neurons, overexpression and RNAi knockdown of PAT1a, cell surface quantification","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus RNAi plus localization, multiple methods, single lab","pmids":["17050537"],"is_preprint":false},{"year":2007,"finding":"APLP1 is a direct transcriptional target of p53; a p53 responsive element in the first intron of the APLP1 gene locus was characterized in vitro and in vivo. APLP1 is required for proliferation of fibroblastic and epithelial cells; depletion of APLP1 diminishes stress-induced apoptosis of neural cells, whereas ectopic APLP1 expression augments apoptosis.","method":"DNA microarray, p53 responsive element characterization (in vivo and in vitro), APLP1 knockdown experiments in neural cells, ectopic overexpression","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — p53 RE characterization with both in vivo and in vitro approaches plus functional knockdown and OE experiments, single lab","pmids":["17533371"],"is_preprint":false},{"year":2011,"finding":"The E2 domains of APP and APLP1 share a conserved antiparallel mode of dimerization as shown by two crystal structures. Heparin binding induces E2 dimerization; residues at the dimeric interface (including Arg-369 and His-433 in APP) interact with phosphate ions and contribute to heparin binding, suggesting a mechanism for heparin-induced dimerization.","method":"X-ray crystallography of APP E2 and APLP1 E2 domains, biophysical measurements in solution (analytical ultracentrifugation), mutational analysis of heparin-binding residues","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures plus biophysical solution measurements plus mutagenesis, multiple orthogonal methods in one study","pmids":["21574595"],"is_preprint":false},{"year":2011,"finding":"APLP1 and APLP2 form transcriptionally active triple protein complexes with the adaptor protein Mint3 and transcriptional co-activators Taz or Yap; this signaling is regulated by γ-secretase cleavage of APLP1/APLP2. Presence of Mint1 instead of Mint3 prevents nuclear translocation of the complex. APLP1 shows much lower transactivation levels compared to APP and APLP2.","method":"Co-immunoprecipitation, reporter assays for transcriptional activation, nuclear localization analysis in transfected cells","journal":"Journal of Alzheimer's disease : JAD","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus functional reporter assays, multiple orthogonal approaches, single lab","pmids":["21178287"],"is_preprint":false},{"year":2011,"finding":"APLP1 (and APP) are degraded through autophagy in neuronal cells in response to proteasome inhibition; ER stress induced by proteasome inhibitors activates autophagy causing reduction of mature APLP1/APP, and blocking autophagy or JNK rescues their expression. The APLP1 proteolysis is mainly mediated by the autophagy-lysosome pathway.","method":"Pharmacological proteasome inhibition, autophagy inhibition, JNK inhibition in neuronal cells, western blotting for APLP1/APP levels","journal":"Protein & cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pharmacological interventions in neuronal cells with consistent outcomes, single lab","pmids":["21626267"],"is_preprint":false},{"year":2014,"finding":"Zinc ions bind to the E2 domain of APLP1 at a novel zinc-binding site and mediate APLP1 oligomerization (but not APLP2, which has a less surface-exposed zinc-binding site and remains monomeric). Zinc specifically induces APLP1 clustering into multimeric complexes at the plasma membrane. Deletion mutants of APLP1 identified the novel zinc-binding site within E2.","method":"FRET analysis in live cells, APLP1 deletion mutants, zinc ion binding assays, fluorescence microscopy, comparison with APP and APLP2","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — FRET plus deletion mutant analysis plus live cell imaging, multiple orthogonal methods in single study","pmids":["24855651"],"is_preprint":false},{"year":2015,"finding":"APLP1 and APLP2 co-immunoprecipitate with both major NMDA receptor subtypes (GluN1/GluN2A and GluN1/GluN2B) via interaction with the obligatory GluN1 subunit in mammalian cells and adult brain extracts. Both APLP1 and APLP2 enhance GluN1/GluN2A and GluN1/GluN2B cell surface expression.","method":"Co-immunoprecipitation from transfected mammalian cells and adult brain detergent extracts, cell surface expression assays","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP from both expression system and native brain tissue plus functional surface expression assay, single lab","pmids":["25683482"],"is_preprint":false},{"year":2015,"finding":"The crystal structure of APLP1 E2 in apo form and in complex with a heparin dodecasaccharide (2.5 Å) reveals two distinct binding modes: terminal binding specifically recognizing the heparin nonreducing end (similar to heparanase-processed HS chains) and continuous chain binding via a positively charged surface patch. The apo structure shows an unfolded flexible N-terminal helix αA.","method":"X-ray crystallography (apo form and heparin complex at 2.5 Å resolution)","journal":"Acta crystallographica. Section D, Biological crystallography","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures in two states providing atomic-resolution mechanism, single lab but rigorous structural method","pmids":["25760599"],"is_preprint":false},{"year":2015,"finding":"APLP1 deletion (APLP1-KO) in aged mice results in reduced spine density and impaired basal synaptic transmission with reduced mEPSC frequency. Heterologous expression of APLP1 in non-neuronal cells induces presynaptic differentiation in contacting axons of co-cultured neurons (hemi-synapse assay). APLP1 shows increased trans-cellular binding and elevated cell-surface levels due to reduced endocytosis compared to APP. APLP1 also binds MINT/X11 synaptic signaling molecules.","method":"APLP1 knockout mouse analysis (electrophysiology, spine density), hemi-synapse co-culture assay, endocytosis assays, Co-IP for MINT/X11 interaction","journal":"The Journal of neuroscience : the official journal of the Society for Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse electrophysiology plus hemi-synapse assay plus endocytosis plus Co-IP, multiple orthogonal methods with replicated synaptic phenotype","pmids":["28450540"],"is_preprint":false},{"year":2016,"finding":"Zinc induces multimerization of APLP1 and enriches APLP1 at cellular adhesion sites, forming de novo adhesion complexes; APLP1 exhibits stronger zinc-dependent neuronal adhesion than APP or APLP2. Zinc binding also prevents cleavage of APLP1 by extracellular secretases.","method":"Live-cell microscopy, microcontact printing adhesion assay, ELISA for secreted fragments, zinc treatment in cell culture and rat neurons","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple methods (live imaging, adhesion assay, secretase cleavage assay) in single lab","pmids":["26801522"],"is_preprint":false},{"year":2018,"finding":"Full-length APLP1 (but not APP or APLP2) is uniquely cleaved by γ-secretase without prior ectodomain shedding, producing a novel fragment termed sAPLP1γ. Mass spectrometry showed that sAPLP1γ and the longest Aβ-like peptide share the C-terminus. The APLP1 transmembrane sequence is the critical determinant for this direct γ-shedding, and is sufficient to convert larger type-I membrane proteins like APP into direct γ-secretase substrates.","method":"Cell-based biochemical assays, mass spectrometry, domain-swap experiments using APLP1 transmembrane sequence in APP backbone, γ-secretase inhibitor treatment","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — mass spectrometry identification plus domain-swap mechanistic experiments plus pharmacological validation, multiple orthogonal methods","pmids":["29382944"],"is_preprint":false},{"year":2011,"finding":"APLP1 binds to the II-III loop of the voltage-gated calcium channel Cav2.3 and promotes internalization of the channel. Rab5A also binds the same loop and exerts an inhibitory effect on APLP1-mediated channel internalization.","method":"Yeast two-hybrid screen, co-immunoprecipitation confirmation, patch-clamp recordings, surface biotin endocytosis assays in Cav2.3-stably transfected HEK-293 cells","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Y2H plus Co-IP plus functional endocytosis and electrophysiology assays, single lab","pmids":["22178872"],"is_preprint":false},{"year":2024,"finding":"APLP1 interacts with Lag3 to facilitate binding, internalization, transmission, and toxicity of pathologic α-synuclein preformed fibrils (PFF). Deletion of both Aplp1 and Lag3 eliminates dopaminergic neuron loss and behavioral deficits induced by α-syn PFF in vivo. Anti-Lag3 antibody prevents α-syn PFF internalization by disrupting the Aplp1–Lag3 interaction.","method":"Co-immunoprecipitation for Aplp1-Lag3 interaction, double-knockout mouse studies (behavioral and histological endpoints), in vivo α-syn PFF injection, anti-Lag3 antibody treatment","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP plus double KO in vivo with multiple phenotypic readouts plus antibody rescue, multiple orthogonal methods with in vivo validation","pmids":["38821932"],"is_preprint":false},{"year":2020,"finding":"Matriptase directly interacts with APLP1 and cleaves it in cellulo within its E1 ectodomain at arginine 124. Replacing Arg124 with Ala abolishes APLP1 processing by matriptase. Matriptase reduces APLP1 homodimeric interactions as measured by BRET, identifying matriptase as the first protease cleaving APLP1 in its dimerization domain.","method":"Co-immunoprecipitation for matriptase-APLP1 interaction, site-directed mutagenesis (R124A), BRET assay for homodimerization, cell-based cleavage assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — mutagenesis plus BRET plus Co-IP, multiple orthogonal methods, single lab","pmids":["32572095"],"is_preprint":false},{"year":2015,"finding":"APLP1 deficiency in mice increases excitatory synaptic transmission and decreases paired-pulse inhibition of population spikes in the dentate gyrus, indicating reduced network inhibition. Short-term and long-term synaptic plasticity (LTP) are unchanged in APLP1-KO mice.","method":"In vivo field excitatory postsynaptic potential recordings at perforant path-granule cell synapses in APLP1 knockout mice","journal":"The Journal of comparative neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo electrophysiology in KO mice with defined cellular phenotype, single lab","pmids":["25728909"],"is_preprint":false},{"year":2025,"finding":"APLP1 binds SARM1 (an NAD+ hydrolase critical for axonal degeneration) via its auto-inhibitory domain. APLP1 levels increase in proximal axon segments after axonal injury. Knockdown of Aplp1 reduces neuronal NAD+ levels and causes spontaneous SARM1-dependent axon degeneration; Aplp1 knockdown also accelerates injury-induced axonal degeneration.","method":"Yeast two-hybrid screen with SARM1 auto-inhibitory domain as bait, co-immunoprecipitation, Aplp1 knockdown in cultured sensory neurons, NAD+ level measurement, in vitro and in vivo axonal degeneration assays","journal":"Molecular neurobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Y2H plus Co-IP plus functional knockdown with defined NAD+ and degeneration readouts, single lab","pmids":["41324805"],"is_preprint":false},{"year":2015,"finding":"CSF APLP1 peptide levels (APL1β17, APL1β18, APL1β28) show a dose-dependent relative increase while APL1β25 and APL1β27 decrease in response to gamma-secretase modulator E2012 treatment in dogs in vivo, demonstrating that GSMs shift γ-secretase cleavage of APLP1 similarly to how they shift Aβ42/Aβ40 ratios.","method":"Hybrid immunoaffinity mass spectrometry of dog CSF APLP1 peptides before and after GSM E2012 dosing in a randomized crossover design","journal":"Alzheimer's research & therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo pharmacodynamic measurement with mass spectrometry in controlled crossover design, single lab","pmids":["26689589"],"is_preprint":false}],"current_model":"APLP1 is a type I transmembrane glycoprotein of the APP family that localizes predominantly to the neuronal cell surface (unlike APP/APLP2 which are more intracellular), undergoes α-, γ-, and ε-secretase cleavages (and uniquely, direct γ-secretase cleavage without prior ectodomain shedding via its transmembrane sequence), with its intracellular domain transactivating neprilysin via presenilin-dependent processing; it functions as a synaptic cell adhesion molecule through zinc-regulated E2 domain-mediated trans-dimerization, binds partners including Lag3, SARM1, MINT/X11, NMDA receptor GluN1 subunit, PAT1a, and Cav2.3 to regulate α-synuclein transmission, axonal NAD+ homeostasis, vesicular trafficking, and calcium channel internalization; it is also a p53 transcriptional target that promotes apoptosis, and its loss impairs spine density and basal synaptic transmission in aged mice."},"narrative":{"mechanistic_narrative":"APLP1 is a type I transmembrane glycoprotein of the APP family that functions principally as a neuronal cell-surface adhesion and signaling molecule, localizing predominantly to the plasma membrane in contrast to the more intracellular APP and APLP2 [PMID:19126676]. Its ectodomain mediates both cis and trans intercellular interactions through the C-terminal half of the ectodomain [PMID:19126676], and trans-dimerization is driven by the E2 domain, which dimerizes in a conserved antiparallel mode revealed by crystallography and binds heparin/heparan sulfate through defined surface patches [PMID:21574595, PMID:25760599]. Zinc binding at a novel APLP1-specific E2 site induces APLP1 multimerization and clustering at cell-adhesion sites, producing strong zinc-dependent neuronal adhesion and protecting APLP1 from extracellular secretase cleavage [PMID:24855651, PMID:26801522]. Consistent with an adhesion/synaptic role, APLP1 induces presynaptic differentiation in a hemi-synapse assay and binds MINT/X11 signaling adaptors, and its loss in aged mice reduces spine density and impairs basal synaptic transmission [PMID:28450540]. APLP1 undergoes α-, γ-, and ε-like proteolytic processing, and is uniquely cleaved directly by γ-secretase without prior ectodomain shedding, a property determined by its transmembrane sequence and sufficient to convert APP into a direct γ-secretase substrate [PMID:14970212, PMID:20049724, PMID:29382944]. The presenilin/γ-secretase-released intracellular domain transactivates the neprilysin promoter and assembles with Mint3 and Taz/Yap into transcriptionally active nuclear complexes [PMID:15944124, PMID:21178287]. Through its cell-surface partners APLP1 regulates diverse neuronal processes: it binds the GluN1 NMDA receptor subunit to enhance receptor surface expression [PMID:25683482], the Cav2.3 calcium channel to promote its internalization [PMID:22178872], SARM1 to maintain axonal NAD+ homeostasis [PMID:41324805], and Lag3 to mediate uptake, transmission, and toxicity of pathologic α-synuclein fibrils, with combined Aplp1/Lag3 loss abolishing α-synuclein-induced dopaminergic neurodegeneration in vivo [PMID:38821932]. APLP1 is additionally a direct p53 transcriptional target that promotes stress-induced apoptosis [PMID:17533371].","teleology":[{"year":2004,"claim":"Established that APLP1 is proteolytically processed analogously to APP, defining it as a substrate for the same secretase machinery and noting unique modulation by N-glycosylation.","evidence":"Stable transfection of tagged APLP1 in SH-SY5Y cells with protease inhibitors and detection of secreted/C-terminal fragments","pmids":["14970212"],"confidence":"Medium","gaps":["Identity of the responsible proteases not defined in this study","Functional consequence of the fragments unaddressed"]},{"year":2005,"claim":"Answered what the released APLP1 intracellular domain does, showing presenilin-dependent γ-secretase cleavage generates an AICD that transactivates the neprilysin gene, linking APLP1 processing to transcriptional control.","evidence":"AICD transfection, neprilysin promoter reporters, γ-secretase inhibitors, PS1/PS2-deficient cells and mouse brain assays","pmids":["15944124"],"confidence":"High","gaps":["Direct DNA-binding partners of the APLP1 AICD not resolved","Specific contribution of APLP1 versus APP/APLP2 AICD not separated"]},{"year":2006,"claim":"Identified PAT1a as a trafficking adaptor binding the APLP1 sorting signal, explaining how APLP1 surface levels and processing are controlled.","evidence":"In vivo Co-IP, primary neuron co-localization, PAT1a overexpression/RNAi with cell-surface quantification","pmids":["17050537"],"confidence":"Medium","gaps":["Whether PAT1a discriminates APLP1 from APP/APLP2 unclear","Direct binding versus complex-mediated interaction not separated"]},{"year":2007,"claim":"Connected APLP1 to the p53 stress pathway, showing it is a direct transcriptional target that promotes apoptosis and cell proliferation, a role beyond the synaptic context.","evidence":"Microarray, p53 responsive element characterization in vitro and in vivo, knockdown and overexpression in neural/epithelial cells","pmids":["17533371"],"confidence":"Medium","gaps":["Molecular mechanism by which APLP1 promotes apoptosis unknown","Relationship between this proliferative role and neuronal adhesion function unaddressed"]},{"year":2009,"claim":"Defined the distinctive subcellular distribution and adhesion behavior of APLP1, establishing it as a predominantly cell-surface trans-interacting member of the family that heteromerizes with APP to lower Aβ42.","evidence":"Live imaging, FRET, reciprocal Co-IP and deletion mutants in transfected cells","pmids":["19126676"],"confidence":"High","gaps":["Physiological in vivo relevance of APP-APLP1 heteromers not tested","Molecular interface of trans interaction not defined here"]},{"year":2009,"claim":"Characterized the APLP1 γ-cleavage product ALP-1 and human CSF APL1β peptides, establishing APLP1 peptides as non-toxic surrogate readouts of γ-secretase cleavage preference.","evidence":"Stable transfection, anti-APLP1 antibodies, secretase inhibitors, aggregation/toxicity assays, mass spectrometry of CSF and PS1-mutant/GSM cell systems","pmids":["19401174","20049724"],"confidence":"Medium","gaps":["Physiological function of the p3-like peptides unknown","Why ALP-1 is non-aggregating relative to Aβ not mechanistically resolved"]},{"year":2011,"claim":"Provided atomic-level insight into APLP1 dimerization and matrix binding, showing E2 dimerizes antiparallel and heparin binding promotes dimerization via interface residues.","evidence":"X-ray crystallography of APP and APLP1 E2 domains, analytical ultracentrifugation, mutagenesis of heparin-binding residues","pmids":["21574595"],"confidence":"High","gaps":["In vivo role of heparin-induced dimerization not established","Link between dimerization and downstream signaling not shown structurally"]},{"year":2011,"claim":"Extended APLP1 signaling beyond neprilysin by showing the AICD assembles with Mint3 and Taz/Yap into transcriptionally active nuclear complexes regulated by γ-secretase, while Mint1 blocks nuclear entry.","evidence":"Co-IP, transcriptional reporter assays, nuclear localization analysis in transfected cells","pmids":["21178287"],"confidence":"Medium","gaps":["Target genes of the APLP1-Mint3-Taz/Yap complex not identified","Low APLP1 transactivation relative to APP/APLP2 leaves physiological weight unclear"]},{"year":2011,"claim":"Identified Cav2.3 as a partner whose internalization APLP1 promotes, giving APLP1 a direct role in regulating voltage-gated calcium channel surface levels.","evidence":"Yeast two-hybrid, Co-IP, patch-clamp and surface-biotin endocytosis assays in Cav2.3-stable HEK293 cells","pmids":["22178872"],"confidence":"Medium","gaps":["Neuronal/in vivo relevance of APLP1-Cav2.3 regulation untested","Mechanism coupling APLP1 binding to internalization machinery unresolved"]},{"year":2011,"claim":"Showed APLP1 is degraded mainly through the autophagy-lysosome pathway under proteasomal/ER stress, defining a turnover route for the protein.","evidence":"Pharmacological proteasome, autophagy and JNK inhibition with western blotting in neuronal cells","pmids":["21626267"],"confidence":"Medium","gaps":["Signal targeting APLP1 to autophagy not identified","Relevance to disease-associated accumulation not tested"]},{"year":2014,"claim":"Identified a novel APLP1-specific zinc-binding site in E2 that drives APLP1 (but not APLP2) oligomerization and plasma-membrane clustering, providing a metal-dependent control over multimerization.","evidence":"Live-cell FRET, deletion mutants, zinc-binding assays and family comparison","pmids":["24855651"],"confidence":"High","gaps":["Physiological zinc concentrations triggering clustering not defined","Downstream signaling from zinc-induced clusters unaddressed"]},{"year":2015,"claim":"Demonstrated APLP1's synaptic function through loss-of-function, showing reduced spine density and impaired basal transmission in aged KO mice, presynaptic differentiation activity, low endocytosis, and MINT/X11 binding.","evidence":"APLP1-KO mouse electrophysiology and spine analysis, hemi-synapse co-culture, endocytosis assays, Co-IP","pmids":["28450540"],"confidence":"High","gaps":["Trans-synaptic partner mediating presynaptic differentiation not identified","Why phenotype manifests in aged but not young mice unresolved"]},{"year":2015,"claim":"Refined the circuit-level consequence of APLP1 loss, showing increased excitatory transmission and reduced network inhibition in the dentate gyrus with intact plasticity.","evidence":"In vivo field potential recordings at perforant path-granule cell synapses in APLP1-KO mice","pmids":["25728909"],"confidence":"Medium","gaps":["Cellular basis of altered inhibition not defined","Reconciliation with reduced basal transmission reported elsewhere not addressed"]},{"year":2015,"claim":"Resolved how APLP1 engages heparan sulfate at atomic resolution, revealing two distinct binding modes including specific recognition of the heparin nonreducing end.","evidence":"X-ray crystallography of apo and heparin-dodecasaccharide-bound APLP1 E2 at 2.5 Å","pmids":["25760599"],"confidence":"High","gaps":["Functional consequence of nonreducing-end recognition in vivo unknown","Connection to dimerization/adhesion not directly tested"]},{"year":2015,"claim":"Linked APLP1 to glutamatergic signaling by showing it binds the obligatory GluN1 NMDA receptor subunit and enhances receptor surface expression.","evidence":"Co-IP from transfected cells and adult brain extracts, cell-surface expression assays","pmids":["25683482"],"confidence":"Medium","gaps":["Direct versus indirect binding to GluN1 not distinguished","Functional impact on NMDA currents not measured"]},{"year":2015,"claim":"Validated APLP1 CSF peptides as in vivo pharmacodynamic markers, showing GSM E2012 shifts APLP1 γ-cleavage profiles paralleling Aβ42/Aβ40 changes.","evidence":"Hybrid immunoaffinity mass spectrometry of dog CSF in a randomized crossover GSM dosing design","pmids":["26689589"],"confidence":"Medium","gaps":["Human in vivo confirmation not provided here","Functional meaning of the peptide shift for APLP1 biology not addressed"]},{"year":2016,"claim":"Connected zinc-induced APLP1 multimerization to function, showing zinc enriches APLP1 at adhesion sites for de novo neuronal adhesion and protects it from secretase cleavage.","evidence":"Live-cell microscopy, microcontact-printing adhesion assay, ELISA for secreted fragments in cells and rat neurons","pmids":["26801522"],"confidence":"Medium","gaps":["In vivo zinc-dependent adhesion not demonstrated","Receptor on opposing cell surface during adhesion not identified"]},{"year":2018,"claim":"Uncovered a unique processing route in which APLP1 is cleaved directly by γ-secretase without ectodomain shedding, and mapped the determinant to its transmembrane sequence.","evidence":"Cell-based biochemistry, mass spectrometry, APLP1-transmembrane domain-swap into APP, γ-secretase inhibition","pmids":["29382944"],"confidence":"High","gaps":["Physiological function of sAPLP1γ unknown","Whether direct shedding occurs in vivo not established"]},{"year":2020,"claim":"Identified matriptase as the first protease to cleave APLP1 within its dimerization (E1) domain at Arg124, providing a way to disrupt APLP1 homodimers.","evidence":"Co-IP, R124A site-directed mutagenesis, BRET homodimerization assay, cell-based cleavage assay","pmids":["32572095"],"confidence":"Medium","gaps":["Physiological context where matriptase cleaves APLP1 unknown","Consequence of dimer disruption for adhesion/signaling untested in vivo"]},{"year":2024,"claim":"Established APLP1 as a co-receptor with Lag3 for pathologic α-synuclein, with combined deletion abolishing α-synuclein-induced dopaminergic neurodegeneration, defining a disease-relevant function.","evidence":"Co-IP, Aplp1/Lag3 double-knockout mice with behavioral/histological endpoints, in vivo α-syn PFF injection, anti-Lag3 antibody rescue","pmids":["38821932"],"confidence":"High","gaps":["Stoichiometry and direct binding interface of the APLP1-Lag3-αsyn complex not resolved","Whether APLP1 alone can mediate α-syn uptake without Lag3 not separated"]},{"year":2025,"claim":"Linked APLP1 to axonal survival by showing it binds SARM1's auto-inhibitory domain and supports neuronal NAD+ homeostasis, with knockdown causing SARM1-dependent axon degeneration.","evidence":"Yeast two-hybrid, Co-IP, Aplp1 knockdown in sensory neurons, NAD+ measurement, in vitro/in vivo axon degeneration assays","pmids":["41324805"],"confidence":"Medium","gaps":["Whether APLP1 binding inhibits or modulates SARM1 NADase activity not directly shown","Mechanism connecting surface APLP1 to cytoplasmic SARM1 regulation unresolved"]},{"year":null,"claim":"How APLP1's cell-surface adhesion and γ-secretase processing functions are integrated with its multiple intracellular signaling partners (SARM1, Cav2.3, GluN1, p53 pathway) into a unified physiological role remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of full-length APLP1 with transmembrane and cytoplasmic partners","Hierarchy among adhesion, trafficking, and apoptotic functions not established","Direct physiological trans-binding partner at the synapse not identified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[13,14]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[11,16,17,20]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[7,12]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,10,14]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,8]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,15]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[13,19]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6]}],"complexes":[],"partners":["LAG3","SARM1","GLUN1","CACNA1E","PAT1A","MINT/X11","ST14","YAP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P51693","full_name":"Amyloid beta precursor like protein 1","aliases":["Amyloid beta (A4) precursor-like protein 1","Amyloid-like protein 1","APLP","APLP-1"],"length_aa":650,"mass_kda":72.2,"function":"May play a role in postsynaptic function. The C-terminal gamma-secretase processed fragment, ALID1, activates transcription activation through APBB1 (Fe65) binding (By similarity). Couples to JIP signal transduction through C-terminal binding. May interact with cellular G-protein signaling pathways. Can regulate neurite outgrowth through binding to components of the extracellular matrix such as heparin and collagen I The gamma-CTF peptide, C30, is a potent enhancer of neuronal apoptosis","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/P51693/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/APLP1","classification":"Not Classified","n_dependent_lines":23,"n_total_lines":1208,"dependency_fraction":0.01903973509933775},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/APLP1","total_profiled":1310},"omim":[{"mim_id":"617515","title":"RHOMBOID DOMAIN-CONTAINING 1; RHBDD1","url":"https://www.omim.org/entry/617515"},{"mim_id":"604167","title":"CCCTC-BINDING FACTOR; CTCF","url":"https://www.omim.org/entry/604167"},{"mim_id":"602716","title":"NEPHRIN; NPHS1","url":"https://www.omim.org/entry/602716"},{"mim_id":"602710","title":"AMYLOID BETA A4 PRECURSOR PROTEIN-BINDING, FAMILY B, MEMBER 2; APBB2","url":"https://www.omim.org/entry/602710"},{"mim_id":"221770","title":"POLYCYSTIC LIPOMEMBRANOUS OSTEODYSPLASIA WITH SCLEROSING LEUKOENCEPHALOPATHY 1; PLOSL1","url":"https://www.omim.org/entry/221770"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":1120.2}],"url":"https://www.proteinatlas.org/search/APLP1"},"hgnc":{"alias_symbol":["APLP"],"prev_symbol":[]},"alphafold":{"accession":"P51693","domains":[{"cath_id":"3.90.570.10","chopping":"52-145","consensus_level":"medium","plddt":84.7954,"start":52,"end":145},{"cath_id":"3.30.1490.140","chopping":"147-214","consensus_level":"medium","plddt":91.5784,"start":147,"end":214},{"cath_id":"1.20.120.770","chopping":"381-490","consensus_level":"medium","plddt":91.5746,"start":381,"end":490},{"cath_id":"1.10.287","chopping":"314-379","consensus_level":"medium","plddt":92.9353,"start":314,"end":379}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P51693","model_url":"https://alphafold.ebi.ac.uk/files/AF-P51693-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P51693-F1-predicted_aligned_error_v6.png","plddt_mean":68.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=APLP1","jax_strain_url":"https://www.jax.org/strain/search?query=APLP1"},"sequence":{"accession":"P51693","fasta_url":"https://rest.uniprot.org/uniprotkb/P51693.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P51693/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P51693"}},"corpus_meta":[{"pmid":"15944124","id":"PMC_15944124","title":"Presenilin-dependent transcriptional control of the Abeta-degrading enzyme neprilysin by intracellular domains of betaAPP and APLP.","date":"2005","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/15944124","citation_count":289,"is_preprint":false},{"pmid":"14970212","id":"PMC_14970212","title":"The proteolytic processing of the amyloid precursor protein gene family members APLP-1 and APLP-2 involves alpha-, beta-, gamma-, and epsilon-like cleavages: modulation of APLP-1 processing by n-glycosylation.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14970212","citation_count":181,"is_preprint":false},{"pmid":"18284614","id":"PMC_18284614","title":"Increased APLP1 expression and neurodegeneration in the frontal cortex of manganese-exposed non-human primates.","date":"2008","source":"Journal of 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APLP2, members of the APP family of proteins, behave similarly to APP in that they associate with NMDA receptors and enhance NMDA receptor surface expression.","date":"2015","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25683482","citation_count":27,"is_preprint":false},{"pmid":"14597230","id":"PMC_14597230","title":"Accumulation of the amyloid precursor-like protein APLP2 and reduction of APLP1 in retinoic acid-differentiated human neuroblastoma cells upon curcumin-induced neurite retraction.","date":"2003","source":"Brain research. Molecular brain research","url":"https://pubmed.ncbi.nlm.nih.gov/14597230","citation_count":25,"is_preprint":false},{"pmid":"21178287","id":"PMC_21178287","title":"Signaling via amyloid precursor-like proteins APLP1 and APLP2.","date":"2011","source":"Journal of Alzheimer's disease : JAD","url":"https://pubmed.ncbi.nlm.nih.gov/21178287","citation_count":25,"is_preprint":false},{"pmid":"9521588","id":"PMC_9521588","title":"Structure of the human amyloid-precursor-like protein gene APLP1 at 19q13.1.","date":"1998","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9521588","citation_count":21,"is_preprint":false},{"pmid":"26801522","id":"PMC_26801522","title":"Amyloid precursor-like protein 1 (APLP1) exhibits stronger zinc-dependent neuronal adhesion than amyloid precursor protein and APLP2.","date":"2016","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26801522","citation_count":20,"is_preprint":false},{"pmid":"24855651","id":"PMC_24855651","title":"Novel zinc-binding site in the E2 domain regulates amyloid precursor-like protein 1 (APLP1) oligomerization.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24855651","citation_count":20,"is_preprint":false},{"pmid":"19401174","id":"PMC_19401174","title":"gamma-secretase processing of APLP1 leads to the production of a p3-like peptide that does not aggregate and is not toxic to neurons.","date":"2009","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/19401174","citation_count":17,"is_preprint":false},{"pmid":"25728909","id":"PMC_25728909","title":"Deletion of the amyloid precursor-like protein 1 (APLP1) enhances excitatory synaptic transmission, reduces network inhibition but does not impair synaptic plasticity in the mouse dentate gyrus.","date":"2015","source":"The Journal of comparative neurology","url":"https://pubmed.ncbi.nlm.nih.gov/25728909","citation_count":15,"is_preprint":false},{"pmid":"25760599","id":"PMC_25760599","title":"Interaction of the amyloid precursor protein-like protein 1 (APLP1) E2 domain with heparan sulfate involves two distinct binding modes.","date":"2015","source":"Acta crystallographica. Section D, Biological crystallography","url":"https://pubmed.ncbi.nlm.nih.gov/25760599","citation_count":12,"is_preprint":false},{"pmid":"8786110","id":"PMC_8786110","title":"Characterization of the genomic structure of the mouse APLP1 gene.","date":"1996","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8786110","citation_count":12,"is_preprint":false},{"pmid":"26689589","id":"PMC_26689589","title":"APLP1 as a cerebrospinal fluid biomarker for γ-secretase modulator treatment.","date":"2015","source":"Alzheimer's research & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/26689589","citation_count":9,"is_preprint":false},{"pmid":"25740230","id":"PMC_25740230","title":"APLP1 promotes dFoxO-dependent cell death in Drosophila.","date":"2015","source":"Apoptosis : an international journal on programmed cell death","url":"https://pubmed.ncbi.nlm.nih.gov/25740230","citation_count":8,"is_preprint":false},{"pmid":"34050225","id":"PMC_34050225","title":"Rapid evolution of mammalian APLP1 as a synaptic adhesion molecule.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/34050225","citation_count":8,"is_preprint":false},{"pmid":"37199163","id":"PMC_37199163","title":"Comparative binding analysis of WGX50 and Alpha-M with APP family proteins APLP1 and APLP2 using structural-dynamics and free energy calculation approaches.","date":"2023","source":"Physical chemistry chemical physics : PCCP","url":"https://pubmed.ncbi.nlm.nih.gov/37199163","citation_count":8,"is_preprint":false},{"pmid":"39742488","id":"PMC_39742488","title":"Blood-derived APLP1+ extracellular vesicles are potential biomarkers for the early diagnosis of brain diseases.","date":"2025","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/39742488","citation_count":6,"is_preprint":false},{"pmid":"28690498","id":"PMC_28690498","title":"Amyloid-precursor Like Proteins APLP1 and APLP2 Are Dispensable for Normal Development of the Neonatal Respiratory Network.","date":"2017","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/28690498","citation_count":6,"is_preprint":false},{"pmid":"22178872","id":"PMC_22178872","title":"APLP1 and Rab5A interact with the II-III loop of the voltage-gated Ca-channel Ca(v)2.3 and modulate its internalization differently.","date":"2011","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22178872","citation_count":5,"is_preprint":false},{"pmid":"27355212","id":"PMC_27355212","title":"Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27355212","citation_count":4,"is_preprint":false},{"pmid":"36385765","id":"PMC_36385765","title":"Lack of APLP1 leads to subtle alterations in neuronal morphology but does not affect learning and memory.","date":"2022","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/36385765","citation_count":3,"is_preprint":false},{"pmid":"23132356","id":"PMC_23132356","title":"[Species identification of animal hair present as a contaminant in food by PCR-APLP method].","date":"2012","source":"Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan","url":"https://pubmed.ncbi.nlm.nih.gov/23132356","citation_count":3,"is_preprint":false},{"pmid":"19448684","id":"PMC_19448684","title":"Down-regulation of APLP1 mRNA expression in hippocampus of pilocarpine-induced epileptic rats.","date":"2009","source":"Neuroscience bulletin","url":"https://pubmed.ncbi.nlm.nih.gov/19448684","citation_count":2,"is_preprint":false},{"pmid":"27497325","id":"PMC_27497325","title":"Genotyping of the c.1423C>T (p.P475S) polymorphism in the ADAMTS13 gene by APLP and HRM assays: Northeastern Asian origin of the mutant.","date":"2016","source":"Legal medicine (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/27497325","citation_count":2,"is_preprint":false},{"pmid":"26980250","id":"PMC_26980250","title":"The art of traditional native PAGE: The APLP 48-ID assay for human identification.","date":"2015","source":"Legal medicine (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/26980250","citation_count":2,"is_preprint":false},{"pmid":"32572095","id":"PMC_32572095","title":"Matriptase processing of APLP1 ectodomain alters its homodimerization.","date":"2020","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/32572095","citation_count":1,"is_preprint":false},{"pmid":"11060991","id":"PMC_11060991","title":"[Application of the PCR-APLP method to determine ABO genotypes in forensic samples].","date":"2000","source":"Nihon hoigaku zasshi = The Japanese journal of legal medicine","url":"https://pubmed.ncbi.nlm.nih.gov/11060991","citation_count":1,"is_preprint":false},{"pmid":"41324805","id":"PMC_41324805","title":"APLP1 Interacts with SARM1 and Regulates Axonal Maintenance and Post-Injury Degeneration.","date":"2025","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/41324805","citation_count":0,"is_preprint":false},{"pmid":"39968922","id":"PMC_39968922","title":"Assessing Plasma APLP1 for the Progression of Parkinson's Disease: Insights from HSPD and PPMI Cohorts.","date":"2025","source":"Movement disorders : official journal of the Movement Disorder Society","url":"https://pubmed.ncbi.nlm.nih.gov/39968922","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":22866,"output_tokens":5826,"usd":0.077994,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14471,"output_tokens":6379,"usd":0.115915,"stage2_stop_reason":"end_turn"},"total_usd":0.193909,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2005,\n      \"finding\": \"The intracellular domain (AICD) released by presenilin-dependent γ-secretase cleavage of APLP1 (and APP/APLP2) transactivates the neprilysin gene promoter, thereby regulating neprilysin transcription, expression, and activity; this mechanism is presenilin-dependent and does not operate for Notch, N- or E-cadherin cleavage products.\",\n      \"method\": \"Transient transfection of AICD constructs, neprilysin promoter reporter assays, gamma-secretase inhibitor treatment, PS1/PS2-deficient cell lines, mouse brain activity assays\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (reporter assay, KO cells, pharmacological inhibition, in vivo brain activity), replicated across APP family members\",\n      \"pmids\": [\"15944124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"APLP1 undergoes α-, γ-, and ε-like proteolytic cleavages similar to APP; uniquely among APP family members, APLP1 processing can be modulated by N-glycosylation. p3-like fragments of APLP1 were detected in conditioned media of stably transfected cells.\",\n      \"method\": \"Stable transfection of C-terminally tagged APLP1 in SH-SY5Y cells, pharmacological protease inhibitors, detection of C-terminal fragments and secreted peptides\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based biochemical characterization with pharmacological inhibitors and tagged constructs, single lab\",\n      \"pmids\": [\"14970212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"APLP1 localizes predominantly to the cell surface, whereas APP and APLP2 are mostly found in intracellular compartments. APLP1 uniquely forms trans (intercellular) interactions in addition to cis interactions; multimerization of APLP1 depends strongly on the C-terminal half of the ectodomain rather than the N-terminal half required by APP/APLP2. Co-expression of APP with APLP1 or APLP2 reduces Aβ42 generation, attributed to formation of heteromeric complexes.\",\n      \"method\": \"Live cell imaging, FRET, co-immunoprecipitation, deletion mutant analysis in transfected cells\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus FRET plus live imaging, multiple orthogonal methods in single lab study\",\n      \"pmids\": [\"19126676\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"γ-secretase processing of APLP1 produces an ~3.5 kDa p3-like peptide (ALP-1); its production is abolished by γ-secretase inhibition but not β-secretase inhibition. Unlike Aβ or p3, ALP-1 does not aggregate and is not toxic to neurons.\",\n      \"method\": \"Stable transfection of CHO cells with human APLP1, novel anti-APLP1 antibody, gamma- and beta-secretase inhibitor treatment, neurotoxicity and aggregation assays\",\n      \"journal\": \"Brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based biochemical detection with pharmacological inhibitors and orthogonal functional assays, single lab\",\n      \"pmids\": [\"19401174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Human CSF contains three APLP1-derived Aβ-like peptides (APL1β25, APL1β27, APL1β28) generated by β- and γ-cleavages. Gamma-secretase modulators (GSMs) and familial AD presenilin1 mutants that increase Aβ42 production cause a parallel increase in APL1β28; this peptide tracks γ-secretase cleavage preference at the ε/γ site.\",\n      \"method\": \"Mass spectrometry identification of CSF peptides, cell culture treatment with GSMs and PS1 mutants, CSF analysis from PS1 mutation carriers and sporadic AD patients\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS identification plus cell-based pharmacological experiments plus human CSF validation, single lab\",\n      \"pmids\": [\"20049724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PAT1a directly binds to APLP1 (and APP, APLP2) and co-localizes with them in trans-Golgi network vesicles or endosomes in primary neurons. PAT1a interacts with the basolateral sorting signal of APLP1/APP/APLP2; overexpression or RNAi knockdown of PAT1a modulates APLP1/APP/APLP2 levels at the cell surface and promotes their processing.\",\n      \"method\": \"Co-immunoprecipitation in vivo, co-localization in primary neurons, overexpression and RNAi knockdown of PAT1a, cell surface quantification\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus RNAi plus localization, multiple methods, single lab\",\n      \"pmids\": [\"17050537\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"APLP1 is a direct transcriptional target of p53; a p53 responsive element in the first intron of the APLP1 gene locus was characterized in vitro and in vivo. APLP1 is required for proliferation of fibroblastic and epithelial cells; depletion of APLP1 diminishes stress-induced apoptosis of neural cells, whereas ectopic APLP1 expression augments apoptosis.\",\n      \"method\": \"DNA microarray, p53 responsive element characterization (in vivo and in vitro), APLP1 knockdown experiments in neural cells, ectopic overexpression\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — p53 RE characterization with both in vivo and in vitro approaches plus functional knockdown and OE experiments, single lab\",\n      \"pmids\": [\"17533371\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The E2 domains of APP and APLP1 share a conserved antiparallel mode of dimerization as shown by two crystal structures. Heparin binding induces E2 dimerization; residues at the dimeric interface (including Arg-369 and His-433 in APP) interact with phosphate ions and contribute to heparin binding, suggesting a mechanism for heparin-induced dimerization.\",\n      \"method\": \"X-ray crystallography of APP E2 and APLP1 E2 domains, biophysical measurements in solution (analytical ultracentrifugation), mutational analysis of heparin-binding residues\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures plus biophysical solution measurements plus mutagenesis, multiple orthogonal methods in one study\",\n      \"pmids\": [\"21574595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"APLP1 and APLP2 form transcriptionally active triple protein complexes with the adaptor protein Mint3 and transcriptional co-activators Taz or Yap; this signaling is regulated by γ-secretase cleavage of APLP1/APLP2. Presence of Mint1 instead of Mint3 prevents nuclear translocation of the complex. APLP1 shows much lower transactivation levels compared to APP and APLP2.\",\n      \"method\": \"Co-immunoprecipitation, reporter assays for transcriptional activation, nuclear localization analysis in transfected cells\",\n      \"journal\": \"Journal of Alzheimer's disease : JAD\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus functional reporter assays, multiple orthogonal approaches, single lab\",\n      \"pmids\": [\"21178287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"APLP1 (and APP) are degraded through autophagy in neuronal cells in response to proteasome inhibition; ER stress induced by proteasome inhibitors activates autophagy causing reduction of mature APLP1/APP, and blocking autophagy or JNK rescues their expression. The APLP1 proteolysis is mainly mediated by the autophagy-lysosome pathway.\",\n      \"method\": \"Pharmacological proteasome inhibition, autophagy inhibition, JNK inhibition in neuronal cells, western blotting for APLP1/APP levels\",\n      \"journal\": \"Protein & cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pharmacological interventions in neuronal cells with consistent outcomes, single lab\",\n      \"pmids\": [\"21626267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Zinc ions bind to the E2 domain of APLP1 at a novel zinc-binding site and mediate APLP1 oligomerization (but not APLP2, which has a less surface-exposed zinc-binding site and remains monomeric). Zinc specifically induces APLP1 clustering into multimeric complexes at the plasma membrane. Deletion mutants of APLP1 identified the novel zinc-binding site within E2.\",\n      \"method\": \"FRET analysis in live cells, APLP1 deletion mutants, zinc ion binding assays, fluorescence microscopy, comparison with APP and APLP2\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — FRET plus deletion mutant analysis plus live cell imaging, multiple orthogonal methods in single study\",\n      \"pmids\": [\"24855651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"APLP1 and APLP2 co-immunoprecipitate with both major NMDA receptor subtypes (GluN1/GluN2A and GluN1/GluN2B) via interaction with the obligatory GluN1 subunit in mammalian cells and adult brain extracts. Both APLP1 and APLP2 enhance GluN1/GluN2A and GluN1/GluN2B cell surface expression.\",\n      \"method\": \"Co-immunoprecipitation from transfected mammalian cells and adult brain detergent extracts, cell surface expression assays\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP from both expression system and native brain tissue plus functional surface expression assay, single lab\",\n      \"pmids\": [\"25683482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The crystal structure of APLP1 E2 in apo form and in complex with a heparin dodecasaccharide (2.5 Å) reveals two distinct binding modes: terminal binding specifically recognizing the heparin nonreducing end (similar to heparanase-processed HS chains) and continuous chain binding via a positively charged surface patch. The apo structure shows an unfolded flexible N-terminal helix αA.\",\n      \"method\": \"X-ray crystallography (apo form and heparin complex at 2.5 Å resolution)\",\n      \"journal\": \"Acta crystallographica. Section D, Biological crystallography\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures in two states providing atomic-resolution mechanism, single lab but rigorous structural method\",\n      \"pmids\": [\"25760599\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"APLP1 deletion (APLP1-KO) in aged mice results in reduced spine density and impaired basal synaptic transmission with reduced mEPSC frequency. Heterologous expression of APLP1 in non-neuronal cells induces presynaptic differentiation in contacting axons of co-cultured neurons (hemi-synapse assay). APLP1 shows increased trans-cellular binding and elevated cell-surface levels due to reduced endocytosis compared to APP. APLP1 also binds MINT/X11 synaptic signaling molecules.\",\n      \"method\": \"APLP1 knockout mouse analysis (electrophysiology, spine density), hemi-synapse co-culture assay, endocytosis assays, Co-IP for MINT/X11 interaction\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse electrophysiology plus hemi-synapse assay plus endocytosis plus Co-IP, multiple orthogonal methods with replicated synaptic phenotype\",\n      \"pmids\": [\"28450540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Zinc induces multimerization of APLP1 and enriches APLP1 at cellular adhesion sites, forming de novo adhesion complexes; APLP1 exhibits stronger zinc-dependent neuronal adhesion than APP or APLP2. Zinc binding also prevents cleavage of APLP1 by extracellular secretases.\",\n      \"method\": \"Live-cell microscopy, microcontact printing adhesion assay, ELISA for secreted fragments, zinc treatment in cell culture and rat neurons\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple methods (live imaging, adhesion assay, secretase cleavage assay) in single lab\",\n      \"pmids\": [\"26801522\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Full-length APLP1 (but not APP or APLP2) is uniquely cleaved by γ-secretase without prior ectodomain shedding, producing a novel fragment termed sAPLP1γ. Mass spectrometry showed that sAPLP1γ and the longest Aβ-like peptide share the C-terminus. The APLP1 transmembrane sequence is the critical determinant for this direct γ-shedding, and is sufficient to convert larger type-I membrane proteins like APP into direct γ-secretase substrates.\",\n      \"method\": \"Cell-based biochemical assays, mass spectrometry, domain-swap experiments using APLP1 transmembrane sequence in APP backbone, γ-secretase inhibitor treatment\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — mass spectrometry identification plus domain-swap mechanistic experiments plus pharmacological validation, multiple orthogonal methods\",\n      \"pmids\": [\"29382944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"APLP1 binds to the II-III loop of the voltage-gated calcium channel Cav2.3 and promotes internalization of the channel. Rab5A also binds the same loop and exerts an inhibitory effect on APLP1-mediated channel internalization.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation confirmation, patch-clamp recordings, surface biotin endocytosis assays in Cav2.3-stably transfected HEK-293 cells\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Y2H plus Co-IP plus functional endocytosis and electrophysiology assays, single lab\",\n      \"pmids\": [\"22178872\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"APLP1 interacts with Lag3 to facilitate binding, internalization, transmission, and toxicity of pathologic α-synuclein preformed fibrils (PFF). Deletion of both Aplp1 and Lag3 eliminates dopaminergic neuron loss and behavioral deficits induced by α-syn PFF in vivo. Anti-Lag3 antibody prevents α-syn PFF internalization by disrupting the Aplp1–Lag3 interaction.\",\n      \"method\": \"Co-immunoprecipitation for Aplp1-Lag3 interaction, double-knockout mouse studies (behavioral and histological endpoints), in vivo α-syn PFF injection, anti-Lag3 antibody treatment\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP plus double KO in vivo with multiple phenotypic readouts plus antibody rescue, multiple orthogonal methods with in vivo validation\",\n      \"pmids\": [\"38821932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Matriptase directly interacts with APLP1 and cleaves it in cellulo within its E1 ectodomain at arginine 124. Replacing Arg124 with Ala abolishes APLP1 processing by matriptase. Matriptase reduces APLP1 homodimeric interactions as measured by BRET, identifying matriptase as the first protease cleaving APLP1 in its dimerization domain.\",\n      \"method\": \"Co-immunoprecipitation for matriptase-APLP1 interaction, site-directed mutagenesis (R124A), BRET assay for homodimerization, cell-based cleavage assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — mutagenesis plus BRET plus Co-IP, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"32572095\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"APLP1 deficiency in mice increases excitatory synaptic transmission and decreases paired-pulse inhibition of population spikes in the dentate gyrus, indicating reduced network inhibition. Short-term and long-term synaptic plasticity (LTP) are unchanged in APLP1-KO mice.\",\n      \"method\": \"In vivo field excitatory postsynaptic potential recordings at perforant path-granule cell synapses in APLP1 knockout mice\",\n      \"journal\": \"The Journal of comparative neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo electrophysiology in KO mice with defined cellular phenotype, single lab\",\n      \"pmids\": [\"25728909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"APLP1 binds SARM1 (an NAD+ hydrolase critical for axonal degeneration) via its auto-inhibitory domain. APLP1 levels increase in proximal axon segments after axonal injury. Knockdown of Aplp1 reduces neuronal NAD+ levels and causes spontaneous SARM1-dependent axon degeneration; Aplp1 knockdown also accelerates injury-induced axonal degeneration.\",\n      \"method\": \"Yeast two-hybrid screen with SARM1 auto-inhibitory domain as bait, co-immunoprecipitation, Aplp1 knockdown in cultured sensory neurons, NAD+ level measurement, in vitro and in vivo axonal degeneration assays\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Y2H plus Co-IP plus functional knockdown with defined NAD+ and degeneration readouts, single lab\",\n      \"pmids\": [\"41324805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CSF APLP1 peptide levels (APL1β17, APL1β18, APL1β28) show a dose-dependent relative increase while APL1β25 and APL1β27 decrease in response to gamma-secretase modulator E2012 treatment in dogs in vivo, demonstrating that GSMs shift γ-secretase cleavage of APLP1 similarly to how they shift Aβ42/Aβ40 ratios.\",\n      \"method\": \"Hybrid immunoaffinity mass spectrometry of dog CSF APLP1 peptides before and after GSM E2012 dosing in a randomized crossover design\",\n      \"journal\": \"Alzheimer's research & therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo pharmacodynamic measurement with mass spectrometry in controlled crossover design, single lab\",\n      \"pmids\": [\"26689589\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"APLP1 is a type I transmembrane glycoprotein of the APP family that localizes predominantly to the neuronal cell surface (unlike APP/APLP2 which are more intracellular), undergoes α-, γ-, and ε-secretase cleavages (and uniquely, direct γ-secretase cleavage without prior ectodomain shedding via its transmembrane sequence), with its intracellular domain transactivating neprilysin via presenilin-dependent processing; it functions as a synaptic cell adhesion molecule through zinc-regulated E2 domain-mediated trans-dimerization, binds partners including Lag3, SARM1, MINT/X11, NMDA receptor GluN1 subunit, PAT1a, and Cav2.3 to regulate α-synuclein transmission, axonal NAD+ homeostasis, vesicular trafficking, and calcium channel internalization; it is also a p53 transcriptional target that promotes apoptosis, and its loss impairs spine density and basal synaptic transmission in aged mice.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"APLP1 is a type I transmembrane glycoprotein of the APP family that functions principally as a neuronal cell-surface adhesion and signaling molecule, localizing predominantly to the plasma membrane in contrast to the more intracellular APP and APLP2 [#2]. Its ectodomain mediates both cis and trans intercellular interactions through the C-terminal half of the ectodomain [#2], and trans-dimerization is driven by the E2 domain, which dimerizes in a conserved antiparallel mode revealed by crystallography and binds heparin/heparan sulfate through defined surface patches [#7, #12]. Zinc binding at a novel APLP1-specific E2 site induces APLP1 multimerization and clustering at cell-adhesion sites, producing strong zinc-dependent neuronal adhesion and protecting APLP1 from extracellular secretase cleavage [#10, #14]. Consistent with an adhesion/synaptic role, APLP1 induces presynaptic differentiation in a hemi-synapse assay and binds MINT/X11 signaling adaptors, and its loss in aged mice reduces spine density and impairs basal synaptic transmission [#13]. APLP1 undergoes \\u03b1-, \\u03b3-, and \\u03b5-like proteolytic processing, and is uniquely cleaved directly by \\u03b3-secretase without prior ectodomain shedding, a property determined by its transmembrane sequence and sufficient to convert APP into a direct \\u03b3-secretase substrate [#1, #4, #15]. The presenilin/\\u03b3-secretase-released intracellular domain transactivates the neprilysin promoter and assembles with Mint3 and Taz/Yap into transcriptionally active nuclear complexes [#0, #8]. Through its cell-surface partners APLP1 regulates diverse neuronal processes: it binds the GluN1 NMDA receptor subunit to enhance receptor surface expression [#11], the Cav2.3 calcium channel to promote its internalization [#16], SARM1 to maintain axonal NAD+ homeostasis [#20], and Lag3 to mediate uptake, transmission, and toxicity of pathologic \\u03b1-synuclein fibrils, with combined Aplp1/Lag3 loss abolishing \\u03b1-synuclein-induced dopaminergic neurodegeneration in vivo [#17]. APLP1 is additionally a direct p53 transcriptional target that promotes stress-induced apoptosis [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established that APLP1 is proteolytically processed analogously to APP, defining it as a substrate for the same secretase machinery and noting unique modulation by N-glycosylation.\",\n      \"evidence\": \"Stable transfection of tagged APLP1 in SH-SY5Y cells with protease inhibitors and detection of secreted/C-terminal fragments\",\n      \"pmids\": [\"14970212\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of the responsible proteases not defined in this study\", \"Functional consequence of the fragments unaddressed\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Answered what the released APLP1 intracellular domain does, showing presenilin-dependent \\u03b3-secretase cleavage generates an AICD that transactivates the neprilysin gene, linking APLP1 processing to transcriptional control.\",\n      \"evidence\": \"AICD transfection, neprilysin promoter reporters, \\u03b3-secretase inhibitors, PS1/PS2-deficient cells and mouse brain assays\",\n      \"pmids\": [\"15944124\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct DNA-binding partners of the APLP1 AICD not resolved\", \"Specific contribution of APLP1 versus APP/APLP2 AICD not separated\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified PAT1a as a trafficking adaptor binding the APLP1 sorting signal, explaining how APLP1 surface levels and processing are controlled.\",\n      \"evidence\": \"In vivo Co-IP, primary neuron co-localization, PAT1a overexpression/RNAi with cell-surface quantification\",\n      \"pmids\": [\"17050537\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PAT1a discriminates APLP1 from APP/APLP2 unclear\", \"Direct binding versus complex-mediated interaction not separated\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connected APLP1 to the p53 stress pathway, showing it is a direct transcriptional target that promotes apoptosis and cell proliferation, a role beyond the synaptic context.\",\n      \"evidence\": \"Microarray, p53 responsive element characterization in vitro and in vivo, knockdown and overexpression in neural/epithelial cells\",\n      \"pmids\": [\"17533371\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism by which APLP1 promotes apoptosis unknown\", \"Relationship between this proliferative role and neuronal adhesion function unaddressed\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined the distinctive subcellular distribution and adhesion behavior of APLP1, establishing it as a predominantly cell-surface trans-interacting member of the family that heteromerizes with APP to lower A\\u03b242.\",\n      \"evidence\": \"Live imaging, FRET, reciprocal Co-IP and deletion mutants in transfected cells\",\n      \"pmids\": [\"19126676\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological in vivo relevance of APP-APLP1 heteromers not tested\", \"Molecular interface of trans interaction not defined here\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Characterized the APLP1 \\u03b3-cleavage product ALP-1 and human CSF APL1\\u03b2 peptides, establishing APLP1 peptides as non-toxic surrogate readouts of \\u03b3-secretase cleavage preference.\",\n      \"evidence\": \"Stable transfection, anti-APLP1 antibodies, secretase inhibitors, aggregation/toxicity assays, mass spectrometry of CSF and PS1-mutant/GSM cell systems\",\n      \"pmids\": [\"19401174\", \"20049724\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological function of the p3-like peptides unknown\", \"Why ALP-1 is non-aggregating relative to A\\u03b2 not mechanistically resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Provided atomic-level insight into APLP1 dimerization and matrix binding, showing E2 dimerizes antiparallel and heparin binding promotes dimerization via interface residues.\",\n      \"evidence\": \"X-ray crystallography of APP and APLP1 E2 domains, analytical ultracentrifugation, mutagenesis of heparin-binding residues\",\n      \"pmids\": [\"21574595\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo role of heparin-induced dimerization not established\", \"Link between dimerization and downstream signaling not shown structurally\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended APLP1 signaling beyond neprilysin by showing the AICD assembles with Mint3 and Taz/Yap into transcriptionally active nuclear complexes regulated by \\u03b3-secretase, while Mint1 blocks nuclear entry.\",\n      \"evidence\": \"Co-IP, transcriptional reporter assays, nuclear localization analysis in transfected cells\",\n      \"pmids\": [\"21178287\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Target genes of the APLP1-Mint3-Taz/Yap complex not identified\", \"Low APLP1 transactivation relative to APP/APLP2 leaves physiological weight unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified Cav2.3 as a partner whose internalization APLP1 promotes, giving APLP1 a direct role in regulating voltage-gated calcium channel surface levels.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, patch-clamp and surface-biotin endocytosis assays in Cav2.3-stable HEK293 cells\",\n      \"pmids\": [\"22178872\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Neuronal/in vivo relevance of APLP1-Cav2.3 regulation untested\", \"Mechanism coupling APLP1 binding to internalization machinery unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed APLP1 is degraded mainly through the autophagy-lysosome pathway under proteasomal/ER stress, defining a turnover route for the protein.\",\n      \"evidence\": \"Pharmacological proteasome, autophagy and JNK inhibition with western blotting in neuronal cells\",\n      \"pmids\": [\"21626267\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signal targeting APLP1 to autophagy not identified\", \"Relevance to disease-associated accumulation not tested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified a novel APLP1-specific zinc-binding site in E2 that drives APLP1 (but not APLP2) oligomerization and plasma-membrane clustering, providing a metal-dependent control over multimerization.\",\n      \"evidence\": \"Live-cell FRET, deletion mutants, zinc-binding assays and family comparison\",\n      \"pmids\": [\"24855651\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological zinc concentrations triggering clustering not defined\", \"Downstream signaling from zinc-induced clusters unaddressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated APLP1's synaptic function through loss-of-function, showing reduced spine density and impaired basal transmission in aged KO mice, presynaptic differentiation activity, low endocytosis, and MINT/X11 binding.\",\n      \"evidence\": \"APLP1-KO mouse electrophysiology and spine analysis, hemi-synapse co-culture, endocytosis assays, Co-IP\",\n      \"pmids\": [\"28450540\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trans-synaptic partner mediating presynaptic differentiation not identified\", \"Why phenotype manifests in aged but not young mice unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Refined the circuit-level consequence of APLP1 loss, showing increased excitatory transmission and reduced network inhibition in the dentate gyrus with intact plasticity.\",\n      \"evidence\": \"In vivo field potential recordings at perforant path-granule cell synapses in APLP1-KO mice\",\n      \"pmids\": [\"25728909\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cellular basis of altered inhibition not defined\", \"Reconciliation with reduced basal transmission reported elsewhere not addressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Resolved how APLP1 engages heparan sulfate at atomic resolution, revealing two distinct binding modes including specific recognition of the heparin nonreducing end.\",\n      \"evidence\": \"X-ray crystallography of apo and heparin-dodecasaccharide-bound APLP1 E2 at 2.5 \\u00c5\",\n      \"pmids\": [\"25760599\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of nonreducing-end recognition in vivo unknown\", \"Connection to dimerization/adhesion not directly tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linked APLP1 to glutamatergic signaling by showing it binds the obligatory GluN1 NMDA receptor subunit and enhances receptor surface expression.\",\n      \"evidence\": \"Co-IP from transfected cells and adult brain extracts, cell-surface expression assays\",\n      \"pmids\": [\"25683482\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect binding to GluN1 not distinguished\", \"Functional impact on NMDA currents not measured\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Validated APLP1 CSF peptides as in vivo pharmacodynamic markers, showing GSM E2012 shifts APLP1 \\u03b3-cleavage profiles paralleling A\\u03b242/A\\u03b240 changes.\",\n      \"evidence\": \"Hybrid immunoaffinity mass spectrometry of dog CSF in a randomized crossover GSM dosing design\",\n      \"pmids\": [\"26689589\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Human in vivo confirmation not provided here\", \"Functional meaning of the peptide shift for APLP1 biology not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connected zinc-induced APLP1 multimerization to function, showing zinc enriches APLP1 at adhesion sites for de novo neuronal adhesion and protects it from secretase cleavage.\",\n      \"evidence\": \"Live-cell microscopy, microcontact-printing adhesion assay, ELISA for secreted fragments in cells and rat neurons\",\n      \"pmids\": [\"26801522\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo zinc-dependent adhesion not demonstrated\", \"Receptor on opposing cell surface during adhesion not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Uncovered a unique processing route in which APLP1 is cleaved directly by \\u03b3-secretase without ectodomain shedding, and mapped the determinant to its transmembrane sequence.\",\n      \"evidence\": \"Cell-based biochemistry, mass spectrometry, APLP1-transmembrane domain-swap into APP, \\u03b3-secretase inhibition\",\n      \"pmids\": [\"29382944\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological function of sAPLP1\\u03b3 unknown\", \"Whether direct shedding occurs in vivo not established\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified matriptase as the first protease to cleave APLP1 within its dimerization (E1) domain at Arg124, providing a way to disrupt APLP1 homodimers.\",\n      \"evidence\": \"Co-IP, R124A site-directed mutagenesis, BRET homodimerization assay, cell-based cleavage assay\",\n      \"pmids\": [\"32572095\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological context where matriptase cleaves APLP1 unknown\", \"Consequence of dimer disruption for adhesion/signaling untested in vivo\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established APLP1 as a co-receptor with Lag3 for pathologic \\u03b1-synuclein, with combined deletion abolishing \\u03b1-synuclein-induced dopaminergic neurodegeneration, defining a disease-relevant function.\",\n      \"evidence\": \"Co-IP, Aplp1/Lag3 double-knockout mice with behavioral/histological endpoints, in vivo \\u03b1-syn PFF injection, anti-Lag3 antibody rescue\",\n      \"pmids\": [\"38821932\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and direct binding interface of the APLP1-Lag3-\\u03b1syn complex not resolved\", \"Whether APLP1 alone can mediate \\u03b1-syn uptake without Lag3 not separated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked APLP1 to axonal survival by showing it binds SARM1's auto-inhibitory domain and supports neuronal NAD+ homeostasis, with knockdown causing SARM1-dependent axon degeneration.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, Aplp1 knockdown in sensory neurons, NAD+ measurement, in vitro/in vivo axon degeneration assays\",\n      \"pmids\": [\"41324805\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether APLP1 binding inhibits or modulates SARM1 NADase activity not directly shown\", \"Mechanism connecting surface APLP1 to cytoplasmic SARM1 regulation unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How APLP1's cell-surface adhesion and \\u03b3-secretase processing functions are integrated with its multiple intracellular signaling partners (SARM1, Cav2.3, GluN1, p53 pathway) into a unified physiological role remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of full-length APLP1 with transmembrane and cytoplasmic partners\", \"Hierarchy among adhesion, trafficking, and apoptotic functions not established\", \"Direct physiological trans-binding partner at the synapse not identified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [13, 14]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [11, 16, 17, 20]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [7, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 10, 14]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 15]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [13, 19]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"LAG3\", \"SARM1\", \"GLUN1\", \"CACNA1E\", \"PAT1a\", \"MINT/X11\", \"ST14\", \"YAP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}