{"gene":"DERL2","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2006,"finding":"Derlin-2 is a component of mammalian ERAD machinery that physically associates with EDEM (a receptor for misfolded glycoproteins) and p97 (cytosolic ATPase responsible for substrate extraction), providing the mechanistic link between EDEM-mediated substrate recognition and p97-mediated retrotranslocation. Overexpression accelerated degradation of misfolded glycoprotein; knockdown blocked it. Derlin-2 is transcriptionally upregulated by the IRE1 branch of the UPR.","method":"Co-immunoprecipitation (Derlin-2 with EDEM and p97), overexpression and siRNA knockdown degradation assays, UPR branch-specific induction analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, gain-of-function, loss-of-function assays, multiple orthogonal methods, replicated by subsequent studies","pmids":["16449189"],"is_preprint":false},{"year":2006,"finding":"Derlin-2 is required for murine polyomavirus (Py) infection. Inhibition by dominant-negative Derlin-2 or shRNA knockdown blocked Py infection by 50–75%. The block occurs after virus reaches the ER lumen and can be bypassed by direct cytosolic introduction of Py DNA, indicating Derlin-2 facilitates viral genome translocation from the ER to the cytosol via the ERAD retrotranslocation machinery.","method":"Dominant-negative overexpression, shRNA knockdown, viral infection assays with cytosolic DNA bypass experiment","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — dominant-negative and shRNA approaches with mechanistic bypass experiment, single lab, multiple orthogonal methods","pmids":["16912321"],"is_preprint":false},{"year":2011,"finding":"In vivo conditional knockout of Derlin-2 causes constitutive upregulation of ER chaperones and IRE1-mediated UPR in most tissues, perinatal lethality, and skeletal dysplasia in surviving mice due to defects in collagen matrix protein secretion by costal chondrocytes, establishing Derlin-2 as essential for protein dislocation in chondrocytes in vivo. B lymphocyte development, antibody secretion, and hepatocyte function were unaffected by Derlin-2 deletion.","method":"Conditional knockout mice (Cre-lox), histology, ER chaperone/UPR marker analysis, tissue-specific deletion","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic KO with specific phenotypic readouts and tissue-specific controls, single lab","pmids":["21220515"],"is_preprint":false},{"year":2015,"finding":"Derlin-2, together with p97 and HRD1, is required for proteasomal degradation of proinsulin via ERAD. shRNA-mediated silencing of Derlin-2 increased steady-state proinsulin levels, demonstrating Derlin-2 participates in the retrotranslocation/degradation of proinsulin in pancreatic beta cells.","method":"shRNA knockdown, steady-state protein level quantification (Western blot), MHC class I peptide ligandome analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — shRNA knockdown with protein level readout, single lab, single primary method","pmids":["26107514"],"is_preprint":false},{"year":2021,"finding":"Derlin-2 deficiency in the central nervous system impairs postnatal cerebellar and striatal development and causes motor control deficits. Mechanistically, Derlin-2 deficiency inhibits SREBP-2-mediated cholesterol biosynthesis in the brain, and reduced neurite outgrowth caused by Derlin-1 deficiency (a closely related family member) is rescued by SREBP-2 pathway activation, linking Derlin-2 function to brain cholesterol biosynthesis beyond classical ERAD.","method":"CNS-specific conditional knockout mice, in vitro neurite outgrowth assays, SREBP-2 pathway rescue experiments, behavioral motor testing","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined cellular phenotype, in vitro and in vivo assays, pathway rescue, single lab","pmids":["34355142"],"is_preprint":false},{"year":2017,"finding":"Derlin-2 functions as an ER dislocation channel component in podocytes to mediate ERAD and maintain cellular homeostasis. In derlin-2-deficient podocytes, compensatory ER stress responses were lost under adriamycin-induced ER dysfunction, and severe cellular injury occurred via a caspase-12-dependent apoptotic pathway. Derlin-2 overexpression in vitro attenuated adriamycin-induced podocyte injury.","method":"Podocyte-specific knockout, adriamycin injury model, caspase-12 pathway analysis, overexpression rescue experiments, mouse and human glomeruli analysis","journal":"American journal of physiology. Renal physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO and overexpression with specific caspase-12 pathway readout, single lab, multiple approaches","pmids":["29167172"],"is_preprint":false},{"year":2023,"finding":"Derlin-2 acts upstream of derlin-1 and Surf4 in the ERAD retrotranslocation of COX-2 (cyclooxygenase-2). Derlin-2 knockdown impedes COX-2 ubiquitylation and its interaction with caveolin-1 and p97 in the cytosol. Derlin-2 interacts with COX-2 in an N-glycosylation-independent manner, while derlin-1, Surf4, and p97 preferentially interact with non-glycosylated COX-2 and Cav-1 preferentially with N-glycosylated COX-2. The derlin-2–derlin-1–Surf4–Cav-1 axis constitutes a retrotranslocation pathway for COX-2 degradation.","method":"CRISPR library screening, siRNA knockdown, co-immunoprecipitation, ubiquitylation assays, N-glycosylation mutant analysis","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR screen plus co-IP, knockdown, and glycosylation mutant approaches, single lab, multiple orthogonal methods","pmids":["37676109"],"is_preprint":false},{"year":2023,"finding":"DERL2 physically interacts with BAG6 (BAG cochaperone 6), stabilizing it by extending its protein half-life, thereby reinforcing BAG6's oncogenic role in cholangiocarcinoma progression and contributing to chemotherapy resistance. Knockout of DERL2 augmented gemcitabine-induced apoptosis in cholangiocarcinoma cells.","method":"Co-immunoprecipitation (DERL2–BAG6 interaction), protein half-life assay, DERL2 overexpression/knockout, in vitro and in vivo tumor growth assays, gemcitabine sensitivity assay","journal":"Journal of physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP with half-life assay and functional rescue, single lab, moderate mechanistic depth","pmids":["37815698"],"is_preprint":false}],"current_model":"DERL2 (Derlin-2) is an ER-resident multi-pass transmembrane protein that functions as a central scaffold of the ERAD retrotranslocation machinery: it associates with EDEM to capture misfolded/misglycosylated ER lumenal substrates, recruits p97 ATPase for substrate extraction to the cytosol, and acts upstream of Derlin-1 and Surf4 in a sequential retrotranslocation complex; its expression is induced by the IRE1 branch of the UPR, it is essential for chondrocyte collagen homeostasis and postnatal brain cholesterol biosynthesis (via SREBP-2) in vivo, it facilitates polyomavirus genome translocation from the ER to the cytosol, and it stabilizes the co-chaperone BAG6 in a non-ERAD context."},"narrative":{"mechanistic_narrative":"DERL2 (Derlin-2) is a core component of the mammalian ER-associated degradation (ERAD) retrotranslocation machinery, coupling recognition of misfolded ER lumenal substrates to their extraction into the cytosol for proteasomal destruction [PMID:16449189]. It physically bridges the misfolded-glycoprotein receptor EDEM and the cytosolic extraction ATPase p97, and its own transcription is induced by the IRE1 branch of the unfolded protein response, integrating it into ER stress signaling [PMID:16449189]. Within retrotranslocation, DERL2 acts upstream of Derlin-1 and Surf4: it engages substrate (COX-2) in an N-glycosylation-independent manner and is required for substrate ubiquitylation and handoff to the Derlin-1–Surf4–caveolin-1–p97 axis [PMID:37676109], and it likewise supports HRD1/p97-dependent degradation of proinsulin [PMID:26107514]. In vivo, DERL2 is essential for protein dislocation in chondrocytes, where its loss disrupts collagen matrix secretion and causes skeletal dysplasia and perinatal lethality with constitutive UPR activation [PMID:21220515], and it maintains ER homeostasis in podocytes, preventing caspase-12-dependent apoptosis under ER stress [PMID:29167172]. Beyond classical ERAD, DERL2 supports postnatal brain development by enabling SREBP-2-mediated cholesterol biosynthesis [PMID:34355142] and stabilizes the co-chaperone BAG6 by extending its half-life, a non-ERAD activity that reinforces tumor progression and chemoresistance in cholangiocarcinoma [PMID:37815698]. DERL2 is also exploited by murine polyomavirus to translocate its genome from the ER lumen to the cytosol [PMID:16912321].","teleology":[{"year":2006,"claim":"Established DERL2 as the mechanistic link between lumenal substrate recognition and cytosolic extraction in ERAD, answering how misfolded glycoproteins are routed for retrotranslocation.","evidence":"Reciprocal co-IP of Derlin-2 with EDEM and p97, plus overexpression and siRNA degradation assays and UPR branch-specific induction analysis","pmids":["16449189"],"confidence":"High","gaps":["Does not resolve whether DERL2 itself forms the conducting channel or only scaffolds the complex","Stoichiometry and structural arrangement of the EDEM–DERL2–p97 complex not defined"]},{"year":2006,"claim":"Showed that DERL2-dependent retrotranslocation is hijacked by a pathogen, demonstrating the machinery can move non-host cargo (viral genome) from ER to cytosol.","evidence":"Dominant-negative overexpression and shRNA knockdown in polyomavirus infection assays with a cytosolic-DNA bypass experiment","pmids":["16912321"],"confidence":"High","gaps":["How the viral particle/genome is physically accommodated by the ERAD channel is unknown","Direct interaction between DERL2 and viral components not established"]},{"year":2011,"claim":"Defined the in vivo physiological requirement for DERL2, showing it is essential for chondrocyte secretory homeostasis but dispensable in some secretory tissues, revealing tissue-specific dependence on this ERAD route.","evidence":"Conditional Cre-lox knockout mice with histology, ER chaperone/UPR marker analysis, and tissue-specific deletions","pmids":["21220515"],"confidence":"High","gaps":["Molecular basis for tissue-selective requirement (chondrocyte vs B cell/hepatocyte) not explained","Specific endogenous chondrocyte substrate(s) not identified"]},{"year":2015,"claim":"Extended DERL2 substrate scope to proinsulin, placing it in an HRD1/p97-dependent degradation route in beta cells.","evidence":"shRNA knockdown with steady-state proinsulin Western blot and MHC class I ligandome analysis","pmids":["26107514"],"confidence":"Medium","gaps":["Single primary method (knockdown) without reconstitution","Direct DERL2–proinsulin interaction not demonstrated"]},{"year":2017,"claim":"Linked DERL2 ERAD function to cell survival, showing its loss removes a compensatory ER stress buffer and triggers caspase-12-dependent apoptosis in podocytes.","evidence":"Podocyte-specific knockout and overexpression rescue in an adriamycin injury model with caspase-12 pathway analysis","pmids":["29167172"],"confidence":"Medium","gaps":["Direct DERL2 substrates in podocytes not identified","Mechanistic connection between DERL2 loss and caspase-12 activation not fully defined"]},{"year":2021,"claim":"Revealed a non-classical DERL2 role in development by connecting it to SREBP-2-driven cholesterol biosynthesis required for postnatal brain maturation.","evidence":"CNS-specific conditional knockout mice, neurite outgrowth assays, SREBP-2 pathway rescue, and behavioral motor testing","pmids":["34355142"],"confidence":"Medium","gaps":["How DERL2 mechanistically engages the SREBP-2 pathway is not resolved","Whether the effect is through canonical ERAD of an SREBP regulator is unclear"]},{"year":2023,"claim":"Ordered the retrotranslocation complex, placing DERL2 upstream of Derlin-1 and Surf4 and defining glycosylation-state-dependent substrate handoff for COX-2.","evidence":"CRISPR library screening, siRNA knockdown, co-IP, ubiquitylation assays, and N-glycosylation mutant analysis","pmids":["37676109"],"confidence":"Medium","gaps":["Structural basis of the sequential DERL2→DERL1→Surf4 handoff unknown","Generality of this ordered axis across other substrates untested"]},{"year":2023,"claim":"Identified a non-ERAD DERL2 activity as a stabilizer of the co-chaperone BAG6, linking DERL2 to oncogenic protein homeostasis and chemoresistance.","evidence":"Co-IP of DERL2–BAG6, protein half-life assay, knockout/overexpression, and gemcitabine sensitivity and tumor growth assays in cholangiocarcinoma","pmids":["37815698"],"confidence":"Medium","gaps":["Mechanism by which DERL2 extends BAG6 half-life is undefined","Whether this requires ERAD machinery or is independent of it is unresolved"]},{"year":null,"claim":"Whether DERL2 itself forms a substrate-conducting channel or acts purely as a scaffold, and the structural architecture of its sequential retrotranslocation complex, remains open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of DERL2 within the retrotranslocon","Pore-forming vs adaptor function unresolved","Comprehensive endogenous substrate repertoire not mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,6]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,6]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,5,6]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,3,6]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0,2]}],"complexes":["ERAD retrotranslocation complex"],"partners":["EDEM","P97","DERLIN-1","SURF4","HRD1","COX-2","BAG6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9GZP9","full_name":"Derlin-2","aliases":["Degradation in endoplasmic reticulum protein 2","DERtrin-2","Der1-like protein 2","F-LAN-1","F-LANa"],"length_aa":239,"mass_kda":27.6,"function":"Functional component of endoplasmic reticulum-associated degradation (ERAD) for misfolded lumenal glycoproteins, but not that of misfolded nonglycoproteins. May act by forming a channel that allows the retrotranslocation of misfolded glycoproteins into the cytosol where they are ubiquitinated and degraded by the proteasome. May mediate the interaction between VCP and misfolded glycoproteins (PubMed:16186509, PubMed:16449189). May also be involved in endoplasmic reticulum stress-induced pre-emptive quality control, a mechanism that selectively attenuates the translocation of newly synthesized proteins into the endoplasmic reticulum and reroutes them to the cytosol for proteasomal degradation (PubMed:26565908) (Microbial infection) In contrast to DERL1, it is not involved in the degradation of MHC class I heavy chains following infection by cytomegaloviruses","subcellular_location":"Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q9GZP9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DERL2","classification":"Not Classified","n_dependent_lines":351,"n_total_lines":1208,"dependency_fraction":0.2905629139072848},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CCDC47","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/search/DERL2","total_profiled":1310},"omim":[{"mim_id":"616175","title":"UBIQUITIN-CONJUGATING ENZYME E2 J1; UBE2J1","url":"https://www.omim.org/entry/616175"},{"mim_id":"610305","title":"DER1-LIKE DOMAIN FAMILY, MEMBER 3; DERL3","url":"https://www.omim.org/entry/610305"},{"mim_id":"610304","title":"DER1-LIKE DOMAIN FAMILY, MEMBER 2; DERL2","url":"https://www.omim.org/entry/610304"},{"mim_id":"609677","title":"OS9 ENDOPLASMIC RETICULUM LECTIN; OS9","url":"https://www.omim.org/entry/609677"},{"mim_id":"608813","title":"DER1-LIKE DOMAIN FAMILY, MEMBER 1; DERL1","url":"https://www.omim.org/entry/608813"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Endoplasmic reticulum","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/DERL2"},"hgnc":{"alias_symbol":["F-LAN-1","FLANa","F-LANa","CGI-101","derlin-2"],"prev_symbol":[]},"alphafold":{"accession":"Q9GZP9","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9GZP9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9GZP9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9GZP9-F1-predicted_aligned_error_v6.png","plddt_mean":81.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DERL2","jax_strain_url":"https://www.jax.org/strain/search?query=DERL2"},"sequence":{"accession":"Q9GZP9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9GZP9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9GZP9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9GZP9"}},"corpus_meta":[{"pmid":"16449189","id":"PMC_16449189","title":"Derlin-2 and Derlin-3 are regulated by the mammalian unfolded protein response and are required for ER-associated degradation.","date":"2006","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/16449189","citation_count":298,"is_preprint":false},{"pmid":"16912321","id":"PMC_16912321","title":"Murine polyomavirus requires the endoplasmic reticulum protein Derlin-2 to initiate infection.","date":"2006","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/16912321","citation_count":87,"is_preprint":false},{"pmid":"21220515","id":"PMC_21220515","title":"Derlin-2-deficient mice reveal an essential role for protein dislocation in chondrocytes.","date":"2011","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/21220515","citation_count":36,"is_preprint":false},{"pmid":"26107514","id":"PMC_26107514","title":"Proteasomal Degradation of Proinsulin Requires Derlin-2, HRD1 and p97.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26107514","citation_count":29,"is_preprint":false},{"pmid":"11587224","id":"PMC_11587224","title":"Characterization of two novel cell lines, DERL-2 (CD56+/CD3+/Tcry5+) and DERL-7 (CD56+/CD3-/TCRgammadelta-), derived from a single patient with CD56+ non-Hodgkin's lymphoma.","date":"2001","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/11587224","citation_count":26,"is_preprint":false},{"pmid":"34355142","id":"PMC_34355142","title":"ERAD components Derlin-1 and Derlin-2 are essential for postnatal brain development and motor function.","date":"2021","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/34355142","citation_count":21,"is_preprint":false},{"pmid":"11500051","id":"PMC_11500051","title":"Cloning and characterization of F-LANa, upregulated in human liver cancer.","date":"2001","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/11500051","citation_count":11,"is_preprint":false},{"pmid":"29167172","id":"PMC_29167172","title":"Podocytes exhibit a specialized protein quality control employing derlin-2 in kidney disease.","date":"2017","source":"American journal of physiology. Renal physiology","url":"https://pubmed.ncbi.nlm.nih.gov/29167172","citation_count":10,"is_preprint":false},{"pmid":"37815698","id":"PMC_37815698","title":"DERL2 (derlin 2) stabilizes BAG6 (BAG cochaperone 6) in chemotherapy resistance of cholangiocarcinoma.","date":"2023","source":"Journal of physiology and biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/37815698","citation_count":7,"is_preprint":false},{"pmid":"37676109","id":"PMC_37676109","title":"Surf4 collaborates with derlin-2 and derlin-1 to mediate cyclooxygenase-2 translocation to the cytosol for degradation.","date":"2023","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/37676109","citation_count":2,"is_preprint":false},{"pmid":"15344319","id":"PMC_15344319","title":"[In silico cloning of evolutionarily conserved mouse F-LANa].","date":"2002","source":"Shi yan sheng wu xue bao","url":"https://pubmed.ncbi.nlm.nih.gov/15344319","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6847,"output_tokens":2378,"usd":0.028105,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9468,"output_tokens":3037,"usd":0.061632,"stage2_stop_reason":"end_turn"},"total_usd":0.089737,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"Derlin-2 is a component of mammalian ERAD machinery that physically associates with EDEM (a receptor for misfolded glycoproteins) and p97 (cytosolic ATPase responsible for substrate extraction), providing the mechanistic link between EDEM-mediated substrate recognition and p97-mediated retrotranslocation. Overexpression accelerated degradation of misfolded glycoprotein; knockdown blocked it. Derlin-2 is transcriptionally upregulated by the IRE1 branch of the UPR.\",\n      \"method\": \"Co-immunoprecipitation (Derlin-2 with EDEM and p97), overexpression and siRNA knockdown degradation assays, UPR branch-specific induction analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, gain-of-function, loss-of-function assays, multiple orthogonal methods, replicated by subsequent studies\",\n      \"pmids\": [\"16449189\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Derlin-2 is required for murine polyomavirus (Py) infection. Inhibition by dominant-negative Derlin-2 or shRNA knockdown blocked Py infection by 50–75%. The block occurs after virus reaches the ER lumen and can be bypassed by direct cytosolic introduction of Py DNA, indicating Derlin-2 facilitates viral genome translocation from the ER to the cytosol via the ERAD retrotranslocation machinery.\",\n      \"method\": \"Dominant-negative overexpression, shRNA knockdown, viral infection assays with cytosolic DNA bypass experiment\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — dominant-negative and shRNA approaches with mechanistic bypass experiment, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"16912321\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In vivo conditional knockout of Derlin-2 causes constitutive upregulation of ER chaperones and IRE1-mediated UPR in most tissues, perinatal lethality, and skeletal dysplasia in surviving mice due to defects in collagen matrix protein secretion by costal chondrocytes, establishing Derlin-2 as essential for protein dislocation in chondrocytes in vivo. B lymphocyte development, antibody secretion, and hepatocyte function were unaffected by Derlin-2 deletion.\",\n      \"method\": \"Conditional knockout mice (Cre-lox), histology, ER chaperone/UPR marker analysis, tissue-specific deletion\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO with specific phenotypic readouts and tissue-specific controls, single lab\",\n      \"pmids\": [\"21220515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Derlin-2, together with p97 and HRD1, is required for proteasomal degradation of proinsulin via ERAD. shRNA-mediated silencing of Derlin-2 increased steady-state proinsulin levels, demonstrating Derlin-2 participates in the retrotranslocation/degradation of proinsulin in pancreatic beta cells.\",\n      \"method\": \"shRNA knockdown, steady-state protein level quantification (Western blot), MHC class I peptide ligandome analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — shRNA knockdown with protein level readout, single lab, single primary method\",\n      \"pmids\": [\"26107514\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Derlin-2 deficiency in the central nervous system impairs postnatal cerebellar and striatal development and causes motor control deficits. Mechanistically, Derlin-2 deficiency inhibits SREBP-2-mediated cholesterol biosynthesis in the brain, and reduced neurite outgrowth caused by Derlin-1 deficiency (a closely related family member) is rescued by SREBP-2 pathway activation, linking Derlin-2 function to brain cholesterol biosynthesis beyond classical ERAD.\",\n      \"method\": \"CNS-specific conditional knockout mice, in vitro neurite outgrowth assays, SREBP-2 pathway rescue experiments, behavioral motor testing\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined cellular phenotype, in vitro and in vivo assays, pathway rescue, single lab\",\n      \"pmids\": [\"34355142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Derlin-2 functions as an ER dislocation channel component in podocytes to mediate ERAD and maintain cellular homeostasis. In derlin-2-deficient podocytes, compensatory ER stress responses were lost under adriamycin-induced ER dysfunction, and severe cellular injury occurred via a caspase-12-dependent apoptotic pathway. Derlin-2 overexpression in vitro attenuated adriamycin-induced podocyte injury.\",\n      \"method\": \"Podocyte-specific knockout, adriamycin injury model, caspase-12 pathway analysis, overexpression rescue experiments, mouse and human glomeruli analysis\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO and overexpression with specific caspase-12 pathway readout, single lab, multiple approaches\",\n      \"pmids\": [\"29167172\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Derlin-2 acts upstream of derlin-1 and Surf4 in the ERAD retrotranslocation of COX-2 (cyclooxygenase-2). Derlin-2 knockdown impedes COX-2 ubiquitylation and its interaction with caveolin-1 and p97 in the cytosol. Derlin-2 interacts with COX-2 in an N-glycosylation-independent manner, while derlin-1, Surf4, and p97 preferentially interact with non-glycosylated COX-2 and Cav-1 preferentially with N-glycosylated COX-2. The derlin-2–derlin-1–Surf4–Cav-1 axis constitutes a retrotranslocation pathway for COX-2 degradation.\",\n      \"method\": \"CRISPR library screening, siRNA knockdown, co-immunoprecipitation, ubiquitylation assays, N-glycosylation mutant analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR screen plus co-IP, knockdown, and glycosylation mutant approaches, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"37676109\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DERL2 physically interacts with BAG6 (BAG cochaperone 6), stabilizing it by extending its protein half-life, thereby reinforcing BAG6's oncogenic role in cholangiocarcinoma progression and contributing to chemotherapy resistance. Knockout of DERL2 augmented gemcitabine-induced apoptosis in cholangiocarcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation (DERL2–BAG6 interaction), protein half-life assay, DERL2 overexpression/knockout, in vitro and in vivo tumor growth assays, gemcitabine sensitivity assay\",\n      \"journal\": \"Journal of physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP with half-life assay and functional rescue, single lab, moderate mechanistic depth\",\n      \"pmids\": [\"37815698\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DERL2 (Derlin-2) is an ER-resident multi-pass transmembrane protein that functions as a central scaffold of the ERAD retrotranslocation machinery: it associates with EDEM to capture misfolded/misglycosylated ER lumenal substrates, recruits p97 ATPase for substrate extraction to the cytosol, and acts upstream of Derlin-1 and Surf4 in a sequential retrotranslocation complex; its expression is induced by the IRE1 branch of the UPR, it is essential for chondrocyte collagen homeostasis and postnatal brain cholesterol biosynthesis (via SREBP-2) in vivo, it facilitates polyomavirus genome translocation from the ER to the cytosol, and it stabilizes the co-chaperone BAG6 in a non-ERAD context.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DERL2 (Derlin-2) is a core component of the mammalian ER-associated degradation (ERAD) retrotranslocation machinery, coupling recognition of misfolded ER lumenal substrates to their extraction into the cytosol for proteasomal destruction [#0]. It physically bridges the misfolded-glycoprotein receptor EDEM and the cytosolic extraction ATPase p97, and its own transcription is induced by the IRE1 branch of the unfolded protein response, integrating it into ER stress signaling [#0]. Within retrotranslocation, DERL2 acts upstream of Derlin-1 and Surf4: it engages substrate (COX-2) in an N-glycosylation-independent manner and is required for substrate ubiquitylation and handoff to the Derlin-1\\u2013Surf4\\u2013caveolin-1\\u2013p97 axis [#6], and it likewise supports HRD1/p97-dependent degradation of proinsulin [#3]. In vivo, DERL2 is essential for protein dislocation in chondrocytes, where its loss disrupts collagen matrix secretion and causes skeletal dysplasia and perinatal lethality with constitutive UPR activation [#2], and it maintains ER homeostasis in podocytes, preventing caspase-12-dependent apoptosis under ER stress [#5]. Beyond classical ERAD, DERL2 supports postnatal brain development by enabling SREBP-2-mediated cholesterol biosynthesis [#4] and stabilizes the co-chaperone BAG6 by extending its half-life, a non-ERAD activity that reinforces tumor progression and chemoresistance in cholangiocarcinoma [#7]. DERL2 is also exploited by murine polyomavirus to translocate its genome from the ER lumen to the cytosol [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established DERL2 as the mechanistic link between lumenal substrate recognition and cytosolic extraction in ERAD, answering how misfolded glycoproteins are routed for retrotranslocation.\",\n      \"evidence\": \"Reciprocal co-IP of Derlin-2 with EDEM and p97, plus overexpression and siRNA degradation assays and UPR branch-specific induction analysis\",\n      \"pmids\": [\"16449189\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not resolve whether DERL2 itself forms the conducting channel or only scaffolds the complex\", \"Stoichiometry and structural arrangement of the EDEM\\u2013DERL2\\u2013p97 complex not defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed that DERL2-dependent retrotranslocation is hijacked by a pathogen, demonstrating the machinery can move non-host cargo (viral genome) from ER to cytosol.\",\n      \"evidence\": \"Dominant-negative overexpression and shRNA knockdown in polyomavirus infection assays with a cytosolic-DNA bypass experiment\",\n      \"pmids\": [\"16912321\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How the viral particle/genome is physically accommodated by the ERAD channel is unknown\", \"Direct interaction between DERL2 and viral components not established\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined the in vivo physiological requirement for DERL2, showing it is essential for chondrocyte secretory homeostasis but dispensable in some secretory tissues, revealing tissue-specific dependence on this ERAD route.\",\n      \"evidence\": \"Conditional Cre-lox knockout mice with histology, ER chaperone/UPR marker analysis, and tissue-specific deletions\",\n      \"pmids\": [\"21220515\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis for tissue-selective requirement (chondrocyte vs B cell/hepatocyte) not explained\", \"Specific endogenous chondrocyte substrate(s) not identified\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extended DERL2 substrate scope to proinsulin, placing it in an HRD1/p97-dependent degradation route in beta cells.\",\n      \"evidence\": \"shRNA knockdown with steady-state proinsulin Western blot and MHC class I ligandome analysis\",\n      \"pmids\": [\"26107514\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single primary method (knockdown) without reconstitution\", \"Direct DERL2\\u2013proinsulin interaction not demonstrated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Linked DERL2 ERAD function to cell survival, showing its loss removes a compensatory ER stress buffer and triggers caspase-12-dependent apoptosis in podocytes.\",\n      \"evidence\": \"Podocyte-specific knockout and overexpression rescue in an adriamycin injury model with caspase-12 pathway analysis\",\n      \"pmids\": [\"29167172\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct DERL2 substrates in podocytes not identified\", \"Mechanistic connection between DERL2 loss and caspase-12 activation not fully defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed a non-classical DERL2 role in development by connecting it to SREBP-2-driven cholesterol biosynthesis required for postnatal brain maturation.\",\n      \"evidence\": \"CNS-specific conditional knockout mice, neurite outgrowth assays, SREBP-2 pathway rescue, and behavioral motor testing\",\n      \"pmids\": [\"34355142\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How DERL2 mechanistically engages the SREBP-2 pathway is not resolved\", \"Whether the effect is through canonical ERAD of an SREBP regulator is unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Ordered the retrotranslocation complex, placing DERL2 upstream of Derlin-1 and Surf4 and defining glycosylation-state-dependent substrate handoff for COX-2.\",\n      \"evidence\": \"CRISPR library screening, siRNA knockdown, co-IP, ubiquitylation assays, and N-glycosylation mutant analysis\",\n      \"pmids\": [\"37676109\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of the sequential DERL2\\u2192DERL1\\u2192Surf4 handoff unknown\", \"Generality of this ordered axis across other substrates untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified a non-ERAD DERL2 activity as a stabilizer of the co-chaperone BAG6, linking DERL2 to oncogenic protein homeostasis and chemoresistance.\",\n      \"evidence\": \"Co-IP of DERL2\\u2013BAG6, protein half-life assay, knockout/overexpression, and gemcitabine sensitivity and tumor growth assays in cholangiocarcinoma\",\n      \"pmids\": [\"37815698\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which DERL2 extends BAG6 half-life is undefined\", \"Whether this requires ERAD machinery or is independent of it is unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether DERL2 itself forms a substrate-conducting channel or acts purely as a scaffold, and the structural architecture of its sequential retrotranslocation complex, remains open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of DERL2 within the retrotranslocon\", \"Pore-forming vs adaptor function unresolved\", \"Comprehensive endogenous substrate repertoire not mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 6]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 5, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 3, 6]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"complexes\": [\"ERAD retrotranslocation complex\"],\n    \"partners\": [\"EDEM\", \"p97\", \"Derlin-1\", \"Surf4\", \"HRD1\", \"COX-2\", \"BAG6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}