{"gene":"DNAJC5","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":2011,"finding":"DNAJC5/CSPα mutations p.Leu115Arg and p.Leu116del within the cysteine-string domain affect palmitoylation-dependent sorting and reduce the amount of CSPα in neuronal cells, causing adult-onset neuronal ceroid lipofuscinosis.","method":"Linkage mapping, exome sequencing, candidate-gene sequencing, and cellular assays of palmitoylation-dependent sorting in neuronal cells","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (genetic mapping + cellular functional assays), replicated across 20 families and independently confirmed in a second study (PMID:22073189)","pmids":["21820099","22073189"],"is_preprint":false},{"year":2011,"finding":"DNAJC5/CSPα mutations in the cysteine-string domain dramatically decrease membrane affinity of CSPα, potentially altering palmitoylation and intracellular sorting.","method":"In silico structural/functional analysis of mutant CSPα and complementary disease-network analysis","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 4 — primarily computational/in silico prediction without in vitro reconstitution or direct experimental validation","pmids":["22073189"],"is_preprint":false},{"year":2015,"finding":"CSPα is a substrate of the depalmitoylating enzyme PPT1/CLN1; in DNAJC5/CLN4 patient brains, PPT1 is massively increased and mis-localized with dramatically reduced specific enzymatic activity, and global changes in protein palmitoylation occur at lysosomal and synaptic proteins.","method":"Biochemical fractionation, PPT1 enzymatic activity assay, quantitative palmitome proteomics comparing control and DNAJC5/CLN4 patient brains","journal":"Acta neuropathologica","confidence":"High","confidence_rationale":"Tier 1–2 — direct enzymatic assay establishing CSPα as PPT1 substrate, combined with quantitative proteomics in patient tissue","pmids":["26659577"],"is_preprint":false},{"year":2018,"finding":"DNAJC5, as a membrane-associated HSC70 co-chaperone localized preferentially to late endosomes and lysosomes, is an essential mediator of misfolding-associated protein secretion (MAPS); USP19 deubiquitinase binds HSC70 and acts upstream of HSC70 and DNAJC5 in this pathway.","method":"Knockdown/knockout with secretion assays, co-immunoprecipitation, subcellular fractionation/localization, epistasis experiments placing USP19 upstream of HSC70/DNAJC5","journal":"Cell discovery","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (KO, Co-IP, localization, epistasis) in a single study with strong mechanistic detail","pmids":["29531792"],"is_preprint":false},{"year":2019,"finding":"CLN4 mutations cause excessive oligomerization of CSPα/DNAJC5 and its accumulation at prelysosomal (HRS/LAMP1-positive) compartments rather than synaptic vesicles; reducing endogenous wild-type dCSP or Hsc70 gene dosage attenuates CLN4 phenotypes, indicating a hypermorphic gain-of-function mechanism requiring Hsc70.","method":"Drosophila transgenic expression of CLN4 mutant human CSPα, immunofluorescence co-localization, ultrastructural analysis, genetic epistasis (reduction of dCSP and Hsc70)","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis in a well-controlled Drosophila model with multiple orthogonal readouts (localization, ultrastructure, lethality, oligomerization)","pmids":["31663851"],"is_preprint":false},{"year":2022,"finding":"DNAJC5 has two functionally distinct but coupled activities: endolysosome-associated DNAJC5 promotes ESCRT-dependent microautophagy, while a perinuclear/non-lysosomal fraction mediates MAPS; the interactor SLC3A2/CD98hc is essential for perinuclear DNAJC5 localization and MAPS but dispensable for microautophagy. Uncoupling these two processes generates lipofuscin-like autofluorescent storage materials.","method":"Functional proteomics (proximity labeling/BioID), ESCRT pathway inhibition, knockout of SLC3A2, ANCL-mutant CSPα expression, Drosophila ANCL model neurodegeneration assay","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (proteomics, KO, pathway inhibition, in vivo Drosophila validation) establishing mechanistic coupling of MAPS and microautophagy","pmids":["35506243"],"is_preprint":false},{"year":2023,"finding":"DNAJC5 undergoes palmitoylation and forms oligomers anchored on endosomal membranes; palmitoylation is essential for DNAJC5-induced unconventional secretion of α-synuclein, and cytosolic α-syn is actively translocated and sequestered in an endosomal membrane compartment in a DNAJC5-dependent manner.","method":"Reconstitution of α-syn secretion in HEK293T cells by DNAJC5 expression, palmitoylation-deficient mutagenesis, membrane-targeting peptide fusion-induced oligomerization rescue, validation in SH-SY5Y neurons and iPSC-derived dopamine neurons","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 — reconstitution in defined cell system with mutagenesis, replicated in neuronal cell lines and iPSC-derived neurons","pmids":["36626307"],"is_preprint":false},{"year":2024,"finding":"DNAJC5/CSPα interacts with Hsc70, SNAP-25, and STXBP1/Munc18-1 in neuronal (PC12) cells; the L115R ANCL mutation abolishes interactions with SNAP-25 and STXBP1/Munc18-1 but does not affect Hsc70 binding.","method":"Proximity labeling (miniTurbo BioID) in stable PC12 cell lines expressing WT or L115R mutant CSPα, LC-MS proteomics, western blot validation","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 — proximity labeling with MS and western blot validation, single lab but multiple orthogonal methods","pmids":["38193346"],"is_preprint":false},{"year":2021,"finding":"DNAJC5 interacts with SKP2 and enhances degradation of the CDK inhibitor p27 by promoting SKP2-p27 complex formation, driving cell cycle progression in hepatocellular carcinoma cells.","method":"Co-immunoprecipitation, overexpression and knockdown with cell cycle analysis, western blot for p27 levels","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP with functional KD/OE readout but single lab, single method for interaction","pmids":["33662413"],"is_preprint":false},{"year":2025,"finding":"CLN4-linked DNAJC5 mutant aggregates on lysosomal membranes cause direct lysosomal membrane damage; CHIP ubiquitin ligase-mediated microautophagy downregulates CLN4 aggregates to protect lysosomes. Ectopic CHIP improves lysosomal function in CLN4 iPSC-derived neurons.","method":"iPSC-derived neurons with CLN4 mutations, in vitro lysosomal membrane-damaging assay, genome-wide CRISPR screens identifying CHIP, organelle-specific proteomics, Drosophila CLN4 disease model rescue","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1–2 — genome-wide unbiased CRISPR screen, in vitro membrane damage assay, iPSC-neuron model, and in vivo Drosophila rescue","pmids":["40855364"],"is_preprint":false},{"year":2025,"finding":"Palmitoylation of DNAJC5 by DHHC palmitoyl acyltransferases (including DHHC11) controls its subcellular localization; a minimal module (DC95) consisting of the cysteine-string domain plus C-terminal residues is sufficient for palmitoylation, Golgi translocation and unconventional protein secretion, while removal of 5 residues abolishes all three activities.","method":"Mutagenesis of palmitoylation sites, DHHC overexpression assays, subcellular fractionation, secretion assays in human cells","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 1 — in-cell mutagenesis with multiple functional readouts (palmitoylation, localization, secretion) establishing domain requirements","pmids":["41657026"],"is_preprint":false},{"year":2025,"finding":"Neuronal lipofuscinosis and GROD-like structures in mice are caused by gain-of-function CLN4 mutations (Leu115Arg, Leu116Δ) in DNAJC5 and not by loss of CSPα/DNAJC5, establishing a cell-autonomous toxic gain-of-function mechanism for Kufs disease.","method":"Transgenic mouse lines overexpressing WT, Leu115Arg, and Leu116Δ CSPα under Thy1 promoter; conventional and conditional knockout mice; neuropathological analysis","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 — multiple independent transgenic and knockout mouse lines with defined neuropathological readouts","pmids":["40397740"],"is_preprint":false},{"year":2025,"finding":"DNAJC5 is required for secretion of misfolded proteins (including TDP-43) through the endo-lysosomal system in senescent human cells during proteotoxic stress, linking declining proteostasis capacity in senescence to DNAJC5-dependent unconventional secretion.","method":"Multi-dimensional transcriptomics, proteomics of poly-ubiquitylated and granule-forming proteins, DNAJC5 functional requirement assay in senescent vs. proliferating/quiescent cells","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — multi-omics with functional DNAJC5 requirement, but preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.09.07.674107"],"is_preprint":true},{"year":2025,"finding":"DNAJC5 interacts with the intracellular domain of EGFR and with AP2A1 (a clathrin adaptor involved in endocytosis), enhancing EGFR endocytosis and recycling and thereby augmenting EGFR activity and downstream signaling in lung adenocarcinoma cells.","method":"Co-immunoprecipitation, DNAJC5 overexpression/knockdown, AP2A1 knockdown epistasis, in vitro and in vivo proliferation/migration assays","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP interactions with epistasis (AP2A1 KD) and in vivo validation, single lab","pmids":["40374748"],"is_preprint":false},{"year":2014,"finding":"Loss of dnj-14 (C. elegans DNAJC5 orthologue) causes shortened lifespan, impaired locomotion/neurotransmission, and age-dependent neurodegeneration of sensory neurons; resveratrol rescues these phenotypes independently of the sirtuin SIR-2.1, suggesting cAMP-dependent neuroprotection.","method":"C. elegans dnj-14 mutant phenotypic analysis, pharmacological rescue with resveratrol and rolipram, sir-2.1; dnj-14 double mutant epistasis","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis and pharmacological rescue in an established DNAJC5 orthologue model","pmids":["24947438"],"is_preprint":false},{"year":2026,"finding":"TDP43 and hnRNP K regulate canonical splicing of DNAJC5 transcript through direct binding sites; TDP43–hnRNP K interaction is RNA-dependent, and loss of either factor produces aberrant DNAJC5 splicing affecting DNAJC5-mediated endosomal trafficking.","method":"TDP43 and hnRNP K knockdown, splice isoform analysis, RNA-dependent co-immunoprecipitation, mutagenesis of TDP43/hnRNP K binding sites in DNAJC5 pre-mRNA","journal":"Cell biology international","confidence":"Medium","confidence_rationale":"Tier 2 — knockdown with isoform readout, RNA-dependent Co-IP, site mutagenesis; single lab","pmids":["41983529"],"is_preprint":false}],"current_model":"DNAJC5/CSPα is a palmitoylated, membrane-anchored HSC70 co-chaperone that operates at endolysosomes to (1) mediate misfolding-associated protein secretion (MAPS) of cytosolic misfolded proteins including α-synuclein via DHHC-dependent palmitoylation and oligomerization, acting downstream of the USP19–HSC70 deubiquitinase-chaperone axis, and (2) promote ESCRT-dependent endosomal microautophagy, with SLC3A2/CD98hc required for the perinuclear MAPS-competent pool; disease-causing CLN4 mutations in the cysteine-string domain cause a toxic gain-of-function by driving excessive oligomerization and prelysosomal aggregation that directly damages lysosomal membranes, a process counteracted by CHIP ubiquitin ligase-mediated microautophagy, while the interacting depalmitoylase PPT1 regulates CSPα turnover through depalmitoylation."},"narrative":{"teleology":[{"year":2011,"claim":"Establishing that DNAJC5 cysteine-string domain mutations cause a human neurodegenerative disease (CLN4/Kufs) and affect palmitoylation-dependent sorting answered the question of whether CSPα dysfunction is pathogenic in humans.","evidence":"Linkage mapping, exome sequencing across 20 families, and cellular palmitoylation/sorting assays in neuronal cells","pmids":["21820099","22073189"],"confidence":"High","gaps":["Mechanism by which mutations cause neurodegeneration (loss-of-function vs. gain-of-function) was unresolved","No animal model yet recapitulated the disease"]},{"year":2015,"claim":"Identifying CSPα as a PPT1 substrate and showing global palmitoylation disruption in CLN4 brains revealed that DNAJC5 sits at the intersection of two ceroid lipofuscinosis pathways and that its disease state perturbs broader lipid-modification homeostasis.","evidence":"PPT1 enzymatic activity assays and quantitative palmitome proteomics in CLN4 patient versus control brain tissue","pmids":["26659577"],"confidence":"High","gaps":["Whether PPT1 dysregulation is cause or consequence of DNAJC5 aggregation was unclear","No reconstitution of PPT1-mediated CSPα depalmitoylation in a defined system"]},{"year":2018,"claim":"Demonstrating that DNAJC5 is essential for MAPS and acts downstream of USP19–HSC70 on late endosomes/lysosomes defined CSPα's non-synaptic proteostasis function — the secretion of misfolded cytosolic proteins via the endolysosomal system.","evidence":"Knockdown/knockout secretion assays, co-immunoprecipitation, subcellular localization, and epistasis experiments in human cells","pmids":["29531792"],"confidence":"High","gaps":["Cargo selectivity and translocation mechanism for misfolded substrates into endosomes was unknown","In vivo relevance of MAPS not yet tested"]},{"year":2019,"claim":"Genetic epistasis in Drosophila resolved the loss- vs. gain-of-function debate by showing CLN4 mutations cause excessive CSPα oligomerization and prelysosomal accumulation in a hypermorphic, HSC70-dependent manner.","evidence":"Transgenic Drosophila expressing CLN4 mutant human CSPα with genetic reduction of dCSP and Hsc70, immunofluorescence, and ultrastructural analysis","pmids":["31663851"],"confidence":"High","gaps":["Whether the same gain-of-function mechanism operates in mammalian neurons remained untested","Direct demonstration of lysosomal membrane damage was lacking"]},{"year":2022,"claim":"Uncovering that DNAJC5 drives two coupled but separable activities — ESCRT-dependent microautophagy and SLC3A2-dependent MAPS — from distinct endosomal pools explained how its dysfunction generates lipofuscin-like storage material.","evidence":"BioID proximity labeling, SLC3A2 knockout, ESCRT inhibition, ANCL-mutant expression, and Drosophila neurodegeneration assay","pmids":["35506243"],"confidence":"High","gaps":["How SLC3A2 recruits DNAJC5 to the perinuclear compartment was not defined","Relative contribution of microautophagy failure vs. MAPS failure to disease unclear"]},{"year":2023,"claim":"Reconstituting palmitoylation-dependent DNAJC5 oligomerization and α-synuclein translocation into endosomal membranes established the minimal biochemical requirements for MAPS cargo capture.","evidence":"Reconstitution of α-syn secretion by DNAJC5 expression in HEK293T cells, palmitoylation-deficient mutagenesis, membrane-targeting rescue, validated in SH-SY5Y and iPSC-derived dopamine neurons","pmids":["36626307"],"confidence":"High","gaps":["Whether oligomerization directly forms a translocation channel or recruits additional machinery unknown","Stoichiometry of DNAJC5 oligomers on endosomal membranes not determined"]},{"year":2024,"claim":"Proximity labeling in neuronal cells revealed that DNAJC5 interacts with SNAP-25 and Munc18-1, and that the CLN4 L115R mutation selectively abolishes these interactions while preserving HSC70 binding, separating chaperone engagement from synaptic client interactions.","evidence":"MiniTurbo BioID in stable PC12 lines expressing WT or L115R CSPα, LC-MS proteomics, western blot validation","pmids":["38193346"],"confidence":"Medium","gaps":["Reciprocal pull-down or endogenous-level validation not shown","Functional consequence of lost SNAP-25/Munc18-1 interaction for synaptic transmission not tested in this study"]},{"year":2025,"claim":"Convergent studies in transgenic/knockout mice, iPSC-derived neurons, and CRISPR screens established that CLN4 is a cell-autonomous toxic gain-of-function disease in which mutant DNAJC5 aggregates directly damage lysosomal membranes, counteracted by CHIP-mediated microautophagy.","evidence":"Transgenic and conditional-KO mouse neuropathology; in vitro lysosomal membrane damage assay; genome-wide CRISPR screen identifying CHIP; CHIP rescue in CLN4 iPSC neurons and Drosophila","pmids":["40397740","40855364"],"confidence":"High","gaps":["Whether CHIP-based therapeutic strategies are viable in vivo in mammals remains untested","Structural basis of mutant CSPα membrane-damaging activity unresolved"]},{"year":2025,"claim":"Defining a minimal palmitoylation module (DC95) comprising the cysteine-string domain plus C-terminal residues as sufficient for DHHC-dependent palmitoylation, Golgi translocation, and unconventional secretion delineated the domain architecture governing DNAJC5 membrane targeting.","evidence":"Systematic mutagenesis of palmitoylation sites, DHHC overexpression, subcellular fractionation, and secretion assays in human cells","pmids":["41657026"],"confidence":"High","gaps":["Which DHHC isoform is the physiologically dominant palmitoylase in neurons not resolved","Structural basis of how the C-terminal residues cooperate with the cysteine-string for palmitoylation unknown"]},{"year":2025,"claim":"Identifying TDP-43 and hnRNP K as regulators of canonical DNAJC5 splicing revealed a transcriptional-level control point, connecting TDP-43 proteinopathy to DNAJC5-dependent endosomal trafficking.","evidence":"TDP-43/hnRNP K knockdown, splice isoform analysis, RNA-dependent co-immunoprecipitation, binding-site mutagenesis in DNAJC5 pre-mRNA","pmids":["41983529"],"confidence":"Medium","gaps":["In vivo relevance of aberrant DNAJC5 splicing in TDP-43 proteinopathies not demonstrated","Whether mis-spliced DNAJC5 produces a dominant-negative or loss-of-function allele unclear"]},{"year":null,"claim":"The structural basis of DNAJC5 oligomerization on endosomal membranes, the mechanism by which cytosolic misfolded cargoes are translocated across the endosomal membrane, and the in vivo therapeutic potential of modulating CHIP or DHHC enzymes in CLN4 remain open questions.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of membrane-associated DNAJC5 oligomer","Translocation mechanism for MAPS cargo across endosomal membrane undefined","Therapeutic targeting of CHIP or palmitoylation for CLN4 not tested in mammalian models"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[3,4,7]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0,6,10]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[3,5,6]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[3,4,9]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[10]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[3,6]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5,9]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[3,6,10]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,5,6]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,4,9,11]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,6,10]}],"complexes":[],"partners":["HSPA8","PPT1","SNAP25","STXBP1","SLC3A2","STUB1","USP19","AP2A1"],"other_free_text":[]},"mechanistic_narrative":"DNAJC5 (CSPα) is a palmitoylated, membrane-anchored HSC70 co-chaperone that operates at endolysosomes to maintain cellular proteostasis through two coupled activities: misfolding-associated protein secretion (MAPS) of cytosolic misfolded proteins such as α-synuclein and TDP-43, and ESCRT-dependent endosomal microautophagy [PMID:29531792, PMID:36626307, PMID:35506243]. Palmitoylation by DHHC acyltransferases is required for DNAJC5 membrane anchoring, oligomerization, and unconventional secretion; the depalmitoylase PPT1 regulates its turnover, and the interactor SLC3A2/CD98hc directs a perinuclear MAPS-competent pool distinct from the microautophagy-associated lysosomal pool [PMID:41657026, PMID:26659577, PMID:35506243]. In neurons, DNAJC5 also interacts with the synaptic proteins SNAP-25 and Munc18-1 in an HSC70-dependent manner [PMID:38193346]. Dominant mutations (L115R, L116Δ) in the cysteine-string domain cause adult-onset neuronal ceroid lipofuscinosis (Kufs disease/CLN4) through a toxic gain-of-function mechanism involving excessive oligomerization and prelysosomal aggregation that damages lysosomal membranes, a process counteracted by CHIP ubiquitin ligase–mediated microautophagy [PMID:21820099, PMID:31663851, PMID:40397740, PMID:40855364]."},"prefetch_data":{"uniprot":{"accession":"Q9H3Z4","full_name":"DnaJ homolog subfamily C member 5","aliases":["Ceroid-lipofuscinosis neuronal protein 4","Cysteine string protein","CSP"],"length_aa":198,"mass_kda":22.1,"function":"Acts as a general chaperone in regulated exocytosis (By similarity). Acts as a co-chaperone for the SNARE protein SNAP-25 (By similarity). Involved in the calcium-mediated control of a late stage of exocytosis (By similarity). May have an important role in presynaptic function. May be involved in calcium-dependent neurotransmitter release at nerve endings (By similarity)","subcellular_location":"Cytoplasm, cytosol; Membrane; Cytoplasmic vesicle, secretory vesicle, chromaffin granule membrane; Melanosome; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9H3Z4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DNAJC5","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000101152","cell_line_id":"CID000034","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"vesicles","grade":3},{"compartment":"membrane","grade":2},{"compartment":"nucleoplasm","grade":1}],"interactors":[{"gene":"DNAJA2","stoichiometry":10.0},{"gene":"GDI1","stoichiometry":10.0},{"gene":"HSPA14","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000034","total_profiled":1310},"omim":[{"mim_id":"620526","title":"SMALL GLUTAMINE-RICH TETRATRICOPEPTIDE REPEAT COCHAPERONE, BETA; SGTB","url":"https://www.omim.org/entry/620526"},{"mim_id":"613945","title":"DNAJ/HSP40 HOMOLOG, SUBFAMILY C, MEMBER 5, BETA; DNAJC5B","url":"https://www.omim.org/entry/613945"},{"mim_id":"611203","title":"DNAJ/HSP40 HOMOLOG, SUBFAMILY C, MEMBER 5; DNAJC5","url":"https://www.omim.org/entry/611203"},{"mim_id":"607822","title":"ALZHEIMER DISEASE 3; AD3","url":"https://www.omim.org/entry/607822"},{"mim_id":"603419","title":"SMALL GLUTAMINE-RICH TETRATRICOPEPTIDE REPEAT-CONTAINING COCHAPERONE, ALPHA; SGTA","url":"https://www.omim.org/entry/603419"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Vesicles","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Additional"},{"location":"Perinuclear theca","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"},{"location":"End piece","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/DNAJC5"},"hgnc":{"alias_symbol":["FLJ00118","FLJ13070","DNAJC5A"],"prev_symbol":["CLN4"]},"alphafold":{"accession":"Q9H3Z4","domains":[{"cath_id":"1.20.5","chopping":"103-133","consensus_level":"medium","plddt":74.5448,"start":103,"end":133}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H3Z4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H3Z4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H3Z4-F1-predicted_aligned_error_v6.png","plddt_mean":73.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DNAJC5","jax_strain_url":"https://www.jax.org/strain/search?query=DNAJC5"},"sequence":{"accession":"Q9H3Z4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H3Z4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H3Z4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H3Z4"}},"corpus_meta":[{"pmid":"21820099","id":"PMC_21820099","title":"Mutations in DNAJC5, encoding cysteine-string protein alpha, cause autosomal-dominant adult-onset neuronal ceroid lipofuscinosis.","date":"2011","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21820099","citation_count":214,"is_preprint":false},{"pmid":"22073189","id":"PMC_22073189","title":"Exome-sequencing confirms DNAJC5 mutations as cause of adult neuronal ceroid-lipofuscinosis.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22073189","citation_count":98,"is_preprint":false},{"pmid":"29531792","id":"PMC_29531792","title":"DNAJC5 facilitates USP19-dependent unconventional secretion of misfolded cytosolic proteins.","date":"2018","source":"Cell discovery","url":"https://pubmed.ncbi.nlm.nih.gov/29531792","citation_count":87,"is_preprint":false},{"pmid":"26659577","id":"PMC_26659577","title":"Neuronal ceroid lipofuscinosis with DNAJC5/CSPα mutation has PPT1 pathology and exhibit aberrant protein palmitoylation.","date":"2015","source":"Acta neuropathologica","url":"https://pubmed.ncbi.nlm.nih.gov/26659577","citation_count":68,"is_preprint":false},{"pmid":"22235333","id":"PMC_22235333","title":"Mutations in the gene DNAJC5 cause autosomal dominant Kufs disease in a proportion of cases: study of the Parry family and 8 other families.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22235333","citation_count":67,"is_preprint":false},{"pmid":"22978711","id":"PMC_22978711","title":"Recurrent mutations in DNAJC5 cause autosomal dominant Kufs disease.","date":"2012","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22978711","citation_count":51,"is_preprint":false},{"pmid":"24947438","id":"PMC_24947438","title":"Caenorhabditis elegans dnj-14, the orthologue of the DNAJC5 gene mutated in adult onset neuronal ceroid lipofuscinosis, provides a new platform for neuroprotective drug screening and identifies a SIR-2.1-independent action of resveratrol.","date":"2014","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24947438","citation_count":42,"is_preprint":false},{"pmid":"36626307","id":"PMC_36626307","title":"Unconventional secretion of α-synuclein mediated by palmitoylated DNAJC5 oligomers.","date":"2023","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/36626307","citation_count":41,"is_preprint":false},{"pmid":"35506243","id":"PMC_35506243","title":"Abnormal triaging of misfolded proteins by adult neuronal ceroid lipofuscinosis-associated DNAJC5/CSPα mutants causes lipofuscin accumulation.","date":"2022","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/35506243","citation_count":35,"is_preprint":false},{"pmid":"33662413","id":"PMC_33662413","title":"DNAJC5 promotes hepatocellular carcinoma cells proliferation though regulating SKP2 mediated p27 degradation.","date":"2021","source":"Biochimica et biophysica acta. 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neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/35462699","citation_count":12,"is_preprint":false},{"pmid":"35620055","id":"PMC_35620055","title":"Safeguarding Lysosomal Homeostasis by DNAJC5/CSPα-Mediated Unconventional Protein Secretion and Endosomal Microautophagy.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35620055","citation_count":11,"is_preprint":false},{"pmid":"38193346","id":"PMC_38193346","title":"Proximity labelling reveals effects of disease-causing mutation on the DNAJC5/cysteine string protein α interactome.","date":"2024","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/38193346","citation_count":6,"is_preprint":false},{"pmid":"40855364","id":"PMC_40855364","title":"CHIP protects lysosomes from CLN4 mutant-induced membrane damage.","date":"2025","source":"Nature cell 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international","url":"https://pubmed.ncbi.nlm.nih.gov/41983529","citation_count":0,"is_preprint":false},{"pmid":"38403745","id":"PMC_38403745","title":"Tissue distribution of cysteine string protein/DNAJC5 in C. elegans analysed by CRISPR/Cas9-mediated tagging of endogenous DNJ-14.","date":"2024","source":"Cell and tissue research","url":"https://pubmed.ncbi.nlm.nih.gov/38403745","citation_count":0,"is_preprint":false},{"pmid":"41657026","id":"PMC_41657026","title":"Palmitoyl Acyltransferases Control the Membrane Localization of DNAJC5 to Regulate Unconventional Protein Secretion.","date":"2026","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/41657026","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.07.674107","title":"Declining intracellular proteostasis capacity drives misfolded protein secretion in senescent human cells","date":"2025-09-08","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.07.674107","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.02.18.638932","title":"CHIP protects lysosomes from CLN4 mutant-induced membrane damages","date":"2025-02-19","source":"bioRxiv","url":"https://doi.org/10.1101/2025.02.18.638932","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14479,"output_tokens":4110,"usd":0.052543},"stage2":{"model":"claude-opus-4-6","input_tokens":7632,"output_tokens":3158,"usd":0.175665},"total_usd":0.228208,"stage1_batch_id":"msgbatch_0118RScg3WGaGkaZRtWZbtce","stage2_batch_id":"msgbatch_01Cpfzvtbj42aqp5oYZ5Te2s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"DNAJC5/CSPα mutations p.Leu115Arg and p.Leu116del within the cysteine-string domain affect palmitoylation-dependent sorting and reduce the amount of CSPα in neuronal cells, causing adult-onset neuronal ceroid lipofuscinosis.\",\n      \"method\": \"Linkage mapping, exome sequencing, candidate-gene sequencing, and cellular assays of palmitoylation-dependent sorting in neuronal cells\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (genetic mapping + cellular functional assays), replicated across 20 families and independently confirmed in a second study (PMID:22073189)\",\n      \"pmids\": [\"21820099\", \"22073189\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"DNAJC5/CSPα mutations in the cysteine-string domain dramatically decrease membrane affinity of CSPα, potentially altering palmitoylation and intracellular sorting.\",\n      \"method\": \"In silico structural/functional analysis of mutant CSPα and complementary disease-network analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — primarily computational/in silico prediction without in vitro reconstitution or direct experimental validation\",\n      \"pmids\": [\"22073189\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CSPα is a substrate of the depalmitoylating enzyme PPT1/CLN1; in DNAJC5/CLN4 patient brains, PPT1 is massively increased and mis-localized with dramatically reduced specific enzymatic activity, and global changes in protein palmitoylation occur at lysosomal and synaptic proteins.\",\n      \"method\": \"Biochemical fractionation, PPT1 enzymatic activity assay, quantitative palmitome proteomics comparing control and DNAJC5/CLN4 patient brains\",\n      \"journal\": \"Acta neuropathologica\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct enzymatic assay establishing CSPα as PPT1 substrate, combined with quantitative proteomics in patient tissue\",\n      \"pmids\": [\"26659577\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"DNAJC5, as a membrane-associated HSC70 co-chaperone localized preferentially to late endosomes and lysosomes, is an essential mediator of misfolding-associated protein secretion (MAPS); USP19 deubiquitinase binds HSC70 and acts upstream of HSC70 and DNAJC5 in this pathway.\",\n      \"method\": \"Knockdown/knockout with secretion assays, co-immunoprecipitation, subcellular fractionation/localization, epistasis experiments placing USP19 upstream of HSC70/DNAJC5\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (KO, Co-IP, localization, epistasis) in a single study with strong mechanistic detail\",\n      \"pmids\": [\"29531792\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CLN4 mutations cause excessive oligomerization of CSPα/DNAJC5 and its accumulation at prelysosomal (HRS/LAMP1-positive) compartments rather than synaptic vesicles; reducing endogenous wild-type dCSP or Hsc70 gene dosage attenuates CLN4 phenotypes, indicating a hypermorphic gain-of-function mechanism requiring Hsc70.\",\n      \"method\": \"Drosophila transgenic expression of CLN4 mutant human CSPα, immunofluorescence co-localization, ultrastructural analysis, genetic epistasis (reduction of dCSP and Hsc70)\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in a well-controlled Drosophila model with multiple orthogonal readouts (localization, ultrastructure, lethality, oligomerization)\",\n      \"pmids\": [\"31663851\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DNAJC5 has two functionally distinct but coupled activities: endolysosome-associated DNAJC5 promotes ESCRT-dependent microautophagy, while a perinuclear/non-lysosomal fraction mediates MAPS; the interactor SLC3A2/CD98hc is essential for perinuclear DNAJC5 localization and MAPS but dispensable for microautophagy. Uncoupling these two processes generates lipofuscin-like autofluorescent storage materials.\",\n      \"method\": \"Functional proteomics (proximity labeling/BioID), ESCRT pathway inhibition, knockout of SLC3A2, ANCL-mutant CSPα expression, Drosophila ANCL model neurodegeneration assay\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (proteomics, KO, pathway inhibition, in vivo Drosophila validation) establishing mechanistic coupling of MAPS and microautophagy\",\n      \"pmids\": [\"35506243\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DNAJC5 undergoes palmitoylation and forms oligomers anchored on endosomal membranes; palmitoylation is essential for DNAJC5-induced unconventional secretion of α-synuclein, and cytosolic α-syn is actively translocated and sequestered in an endosomal membrane compartment in a DNAJC5-dependent manner.\",\n      \"method\": \"Reconstitution of α-syn secretion in HEK293T cells by DNAJC5 expression, palmitoylation-deficient mutagenesis, membrane-targeting peptide fusion-induced oligomerization rescue, validation in SH-SY5Y neurons and iPSC-derived dopamine neurons\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution in defined cell system with mutagenesis, replicated in neuronal cell lines and iPSC-derived neurons\",\n      \"pmids\": [\"36626307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DNAJC5/CSPα interacts with Hsc70, SNAP-25, and STXBP1/Munc18-1 in neuronal (PC12) cells; the L115R ANCL mutation abolishes interactions with SNAP-25 and STXBP1/Munc18-1 but does not affect Hsc70 binding.\",\n      \"method\": \"Proximity labeling (miniTurbo BioID) in stable PC12 cell lines expressing WT or L115R mutant CSPα, LC-MS proteomics, western blot validation\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proximity labeling with MS and western blot validation, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"38193346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"DNAJC5 interacts with SKP2 and enhances degradation of the CDK inhibitor p27 by promoting SKP2-p27 complex formation, driving cell cycle progression in hepatocellular carcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, overexpression and knockdown with cell cycle analysis, western blot for p27 levels\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP with functional KD/OE readout but single lab, single method for interaction\",\n      \"pmids\": [\"33662413\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CLN4-linked DNAJC5 mutant aggregates on lysosomal membranes cause direct lysosomal membrane damage; CHIP ubiquitin ligase-mediated microautophagy downregulates CLN4 aggregates to protect lysosomes. Ectopic CHIP improves lysosomal function in CLN4 iPSC-derived neurons.\",\n      \"method\": \"iPSC-derived neurons with CLN4 mutations, in vitro lysosomal membrane-damaging assay, genome-wide CRISPR screens identifying CHIP, organelle-specific proteomics, Drosophila CLN4 disease model rescue\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — genome-wide unbiased CRISPR screen, in vitro membrane damage assay, iPSC-neuron model, and in vivo Drosophila rescue\",\n      \"pmids\": [\"40855364\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Palmitoylation of DNAJC5 by DHHC palmitoyl acyltransferases (including DHHC11) controls its subcellular localization; a minimal module (DC95) consisting of the cysteine-string domain plus C-terminal residues is sufficient for palmitoylation, Golgi translocation and unconventional protein secretion, while removal of 5 residues abolishes all three activities.\",\n      \"method\": \"Mutagenesis of palmitoylation sites, DHHC overexpression assays, subcellular fractionation, secretion assays in human cells\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in-cell mutagenesis with multiple functional readouts (palmitoylation, localization, secretion) establishing domain requirements\",\n      \"pmids\": [\"41657026\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Neuronal lipofuscinosis and GROD-like structures in mice are caused by gain-of-function CLN4 mutations (Leu115Arg, Leu116Δ) in DNAJC5 and not by loss of CSPα/DNAJC5, establishing a cell-autonomous toxic gain-of-function mechanism for Kufs disease.\",\n      \"method\": \"Transgenic mouse lines overexpressing WT, Leu115Arg, and Leu116Δ CSPα under Thy1 promoter; conventional and conditional knockout mice; neuropathological analysis\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple independent transgenic and knockout mouse lines with defined neuropathological readouts\",\n      \"pmids\": [\"40397740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DNAJC5 is required for secretion of misfolded proteins (including TDP-43) through the endo-lysosomal system in senescent human cells during proteotoxic stress, linking declining proteostasis capacity in senescence to DNAJC5-dependent unconventional secretion.\",\n      \"method\": \"Multi-dimensional transcriptomics, proteomics of poly-ubiquitylated and granule-forming proteins, DNAJC5 functional requirement assay in senescent vs. proliferating/quiescent cells\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multi-omics with functional DNAJC5 requirement, but preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.09.07.674107\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DNAJC5 interacts with the intracellular domain of EGFR and with AP2A1 (a clathrin adaptor involved in endocytosis), enhancing EGFR endocytosis and recycling and thereby augmenting EGFR activity and downstream signaling in lung adenocarcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, DNAJC5 overexpression/knockdown, AP2A1 knockdown epistasis, in vitro and in vivo proliferation/migration assays\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP interactions with epistasis (AP2A1 KD) and in vivo validation, single lab\",\n      \"pmids\": [\"40374748\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Loss of dnj-14 (C. elegans DNAJC5 orthologue) causes shortened lifespan, impaired locomotion/neurotransmission, and age-dependent neurodegeneration of sensory neurons; resveratrol rescues these phenotypes independently of the sirtuin SIR-2.1, suggesting cAMP-dependent neuroprotection.\",\n      \"method\": \"C. elegans dnj-14 mutant phenotypic analysis, pharmacological rescue with resveratrol and rolipram, sir-2.1; dnj-14 double mutant epistasis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis and pharmacological rescue in an established DNAJC5 orthologue model\",\n      \"pmids\": [\"24947438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"TDP43 and hnRNP K regulate canonical splicing of DNAJC5 transcript through direct binding sites; TDP43–hnRNP K interaction is RNA-dependent, and loss of either factor produces aberrant DNAJC5 splicing affecting DNAJC5-mediated endosomal trafficking.\",\n      \"method\": \"TDP43 and hnRNP K knockdown, splice isoform analysis, RNA-dependent co-immunoprecipitation, mutagenesis of TDP43/hnRNP K binding sites in DNAJC5 pre-mRNA\",\n      \"journal\": \"Cell biology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — knockdown with isoform readout, RNA-dependent Co-IP, site mutagenesis; single lab\",\n      \"pmids\": [\"41983529\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DNAJC5/CSPα is a palmitoylated, membrane-anchored HSC70 co-chaperone that operates at endolysosomes to (1) mediate misfolding-associated protein secretion (MAPS) of cytosolic misfolded proteins including α-synuclein via DHHC-dependent palmitoylation and oligomerization, acting downstream of the USP19–HSC70 deubiquitinase-chaperone axis, and (2) promote ESCRT-dependent endosomal microautophagy, with SLC3A2/CD98hc required for the perinuclear MAPS-competent pool; disease-causing CLN4 mutations in the cysteine-string domain cause a toxic gain-of-function by driving excessive oligomerization and prelysosomal aggregation that directly damages lysosomal membranes, a process counteracted by CHIP ubiquitin ligase-mediated microautophagy, while the interacting depalmitoylase PPT1 regulates CSPα turnover through depalmitoylation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"DNAJC5 (CSPα) is a palmitoylated, membrane-anchored HSC70 co-chaperone that operates at endolysosomes to maintain cellular proteostasis through two coupled activities: misfolding-associated protein secretion (MAPS) of cytosolic misfolded proteins such as α-synuclein and TDP-43, and ESCRT-dependent endosomal microautophagy [PMID:29531792, PMID:36626307, PMID:35506243]. Palmitoylation by DHHC acyltransferases is required for DNAJC5 membrane anchoring, oligomerization, and unconventional secretion; the depalmitoylase PPT1 regulates its turnover, and the interactor SLC3A2/CD98hc directs a perinuclear MAPS-competent pool distinct from the microautophagy-associated lysosomal pool [PMID:41657026, PMID:26659577, PMID:35506243]. In neurons, DNAJC5 also interacts with the synaptic proteins SNAP-25 and Munc18-1 in an HSC70-dependent manner [PMID:38193346]. Dominant mutations (L115R, L116Δ) in the cysteine-string domain cause adult-onset neuronal ceroid lipofuscinosis (Kufs disease/CLN4) through a toxic gain-of-function mechanism involving excessive oligomerization and prelysosomal aggregation that damages lysosomal membranes, a process counteracted by CHIP ubiquitin ligase–mediated microautophagy [PMID:21820099, PMID:31663851, PMID:40397740, PMID:40855364].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing that DNAJC5 cysteine-string domain mutations cause a human neurodegenerative disease (CLN4/Kufs) and affect palmitoylation-dependent sorting answered the question of whether CSPα dysfunction is pathogenic in humans.\",\n      \"evidence\": \"Linkage mapping, exome sequencing across 20 families, and cellular palmitoylation/sorting assays in neuronal cells\",\n      \"pmids\": [\"21820099\", \"22073189\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which mutations cause neurodegeneration (loss-of-function vs. gain-of-function) was unresolved\", \"No animal model yet recapitulated the disease\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying CSPα as a PPT1 substrate and showing global palmitoylation disruption in CLN4 brains revealed that DNAJC5 sits at the intersection of two ceroid lipofuscinosis pathways and that its disease state perturbs broader lipid-modification homeostasis.\",\n      \"evidence\": \"PPT1 enzymatic activity assays and quantitative palmitome proteomics in CLN4 patient versus control brain tissue\",\n      \"pmids\": [\"26659577\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PPT1 dysregulation is cause or consequence of DNAJC5 aggregation was unclear\", \"No reconstitution of PPT1-mediated CSPα depalmitoylation in a defined system\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrating that DNAJC5 is essential for MAPS and acts downstream of USP19–HSC70 on late endosomes/lysosomes defined CSPα's non-synaptic proteostasis function — the secretion of misfolded cytosolic proteins via the endolysosomal system.\",\n      \"evidence\": \"Knockdown/knockout secretion assays, co-immunoprecipitation, subcellular localization, and epistasis experiments in human cells\",\n      \"pmids\": [\"29531792\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cargo selectivity and translocation mechanism for misfolded substrates into endosomes was unknown\", \"In vivo relevance of MAPS not yet tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Genetic epistasis in Drosophila resolved the loss- vs. gain-of-function debate by showing CLN4 mutations cause excessive CSPα oligomerization and prelysosomal accumulation in a hypermorphic, HSC70-dependent manner.\",\n      \"evidence\": \"Transgenic Drosophila expressing CLN4 mutant human CSPα with genetic reduction of dCSP and Hsc70, immunofluorescence, and ultrastructural analysis\",\n      \"pmids\": [\"31663851\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the same gain-of-function mechanism operates in mammalian neurons remained untested\", \"Direct demonstration of lysosomal membrane damage was lacking\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Uncovering that DNAJC5 drives two coupled but separable activities — ESCRT-dependent microautophagy and SLC3A2-dependent MAPS — from distinct endosomal pools explained how its dysfunction generates lipofuscin-like storage material.\",\n      \"evidence\": \"BioID proximity labeling, SLC3A2 knockout, ESCRT inhibition, ANCL-mutant expression, and Drosophila neurodegeneration assay\",\n      \"pmids\": [\"35506243\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How SLC3A2 recruits DNAJC5 to the perinuclear compartment was not defined\", \"Relative contribution of microautophagy failure vs. MAPS failure to disease unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Reconstituting palmitoylation-dependent DNAJC5 oligomerization and α-synuclein translocation into endosomal membranes established the minimal biochemical requirements for MAPS cargo capture.\",\n      \"evidence\": \"Reconstitution of α-syn secretion by DNAJC5 expression in HEK293T cells, palmitoylation-deficient mutagenesis, membrane-targeting rescue, validated in SH-SY5Y and iPSC-derived dopamine neurons\",\n      \"pmids\": [\"36626307\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether oligomerization directly forms a translocation channel or recruits additional machinery unknown\", \"Stoichiometry of DNAJC5 oligomers on endosomal membranes not determined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Proximity labeling in neuronal cells revealed that DNAJC5 interacts with SNAP-25 and Munc18-1, and that the CLN4 L115R mutation selectively abolishes these interactions while preserving HSC70 binding, separating chaperone engagement from synaptic client interactions.\",\n      \"evidence\": \"MiniTurbo BioID in stable PC12 lines expressing WT or L115R CSPα, LC-MS proteomics, western blot validation\",\n      \"pmids\": [\"38193346\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reciprocal pull-down or endogenous-level validation not shown\", \"Functional consequence of lost SNAP-25/Munc18-1 interaction for synaptic transmission not tested in this study\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Convergent studies in transgenic/knockout mice, iPSC-derived neurons, and CRISPR screens established that CLN4 is a cell-autonomous toxic gain-of-function disease in which mutant DNAJC5 aggregates directly damage lysosomal membranes, counteracted by CHIP-mediated microautophagy.\",\n      \"evidence\": \"Transgenic and conditional-KO mouse neuropathology; in vitro lysosomal membrane damage assay; genome-wide CRISPR screen identifying CHIP; CHIP rescue in CLN4 iPSC neurons and Drosophila\",\n      \"pmids\": [\"40397740\", \"40855364\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CHIP-based therapeutic strategies are viable in vivo in mammals remains untested\", \"Structural basis of mutant CSPα membrane-damaging activity unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defining a minimal palmitoylation module (DC95) comprising the cysteine-string domain plus C-terminal residues as sufficient for DHHC-dependent palmitoylation, Golgi translocation, and unconventional secretion delineated the domain architecture governing DNAJC5 membrane targeting.\",\n      \"evidence\": \"Systematic mutagenesis of palmitoylation sites, DHHC overexpression, subcellular fractionation, and secretion assays in human cells\",\n      \"pmids\": [\"41657026\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which DHHC isoform is the physiologically dominant palmitoylase in neurons not resolved\", \"Structural basis of how the C-terminal residues cooperate with the cysteine-string for palmitoylation unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identifying TDP-43 and hnRNP K as regulators of canonical DNAJC5 splicing revealed a transcriptional-level control point, connecting TDP-43 proteinopathy to DNAJC5-dependent endosomal trafficking.\",\n      \"evidence\": \"TDP-43/hnRNP K knockdown, splice isoform analysis, RNA-dependent co-immunoprecipitation, binding-site mutagenesis in DNAJC5 pre-mRNA\",\n      \"pmids\": [\"41983529\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance of aberrant DNAJC5 splicing in TDP-43 proteinopathies not demonstrated\", \"Whether mis-spliced DNAJC5 produces a dominant-negative or loss-of-function allele unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis of DNAJC5 oligomerization on endosomal membranes, the mechanism by which cytosolic misfolded cargoes are translocated across the endosomal membrane, and the in vivo therapeutic potential of modulating CHIP or DHHC enzymes in CLN4 remain open questions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of membrane-associated DNAJC5 oligomer\", \"Translocation mechanism for MAPS cargo across endosomal membrane undefined\", \"Therapeutic targeting of CHIP or palmitoylation for CLN4 not tested in mammalian models\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [3, 4, 7]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0, 6, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [3, 5, 6]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [3, 4, 9]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [3, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5, 9]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [3, 6, 10]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 5, 6]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 4, 9, 11]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 6, 10]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"HSPA8\",\n      \"PPT1\",\n      \"SNAP25\",\n      \"STXBP1\",\n      \"SLC3A2\",\n      \"STUB1\",\n      \"USP19\",\n      \"AP2A1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}