{"gene":"KLHL22","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2018,"finding":"In response to amino acids, CUL3-KLHL22 E3 ubiquitin ligase promotes K48-linked polyubiquitination and degradation of DEPDC5 (an essential subunit of the GATOR1 complex), thereby releasing GATOR1-mediated inhibition of Rag GTPases and activating mTORC1 signaling.","method":"Biochemical ubiquitination assays, co-immunoprecipitation, Western blotting, genetic depletion in mammalian cells and C. elegans, xenograft tumor models","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — K48-linked ubiquitination demonstrated biochemically, substrate (DEPDC5) identified with Co-IP, conserved function validated in nematode, multiple orthogonal methods in one rigorous study","pmids":["29769719"],"is_preprint":false},{"year":2020,"finding":"KLHL22, acting as an adaptor of the CUL3-based E3 ligase complex, mediates K48-linked ubiquitination and degradation of PD-1 before its transport to the cell surface, thereby maintaining PD-1 homeostasis and preventing excessive T cell suppression.","method":"Co-immunoprecipitation identifying KLHL22 as a major PD-1-associated protein, genetic depletion (KLHL22 deficiency) leading to PD-1 overaccumulation, Western blotting, functional T cell assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP identifying KLHL22–PD-1 interaction, loss-of-function phenotype (PD-1 overaccumulation), functional T cell assays, single lab with multiple orthogonal methods","pmids":["33109719"],"is_preprint":false},{"year":2013,"finding":"KLHL22 serves as the BTB-KELCH adaptor in a CUL3 E3-ligase complex that targets the mitotic kinase PLK1 for ubiquitination; PLK1 kinase activity is dispensable for its targeting, and CUL3/KLHL22 contacts two distinct motifs within PLK1, consistent with a bivalent mode of substrate targeting.","method":"Co-immunoprecipitation, kinase-dead PLK1 mutant analysis, mapping of interaction motifs within PLK1","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct binding and ubiquitination established with mutant PLK1 and motif mapping, single lab, mechanistic follow-up study","pmids":["24067371"],"is_preprint":false},{"year":2022,"finding":"UBE4B polyubiquitylates and degrades KLHL22; loss of UBE4B causes upregulation of KLHL22 protein levels, which in turn increases DEPDC5 degradation and hyperactivates mTOR, leading to defective neural precursor cell proliferation and differentiation. Suppression of KLHL22 reverses mTOR hyperactivation caused by UBE4B deletion.","method":"Conditional UBE4B knockout mouse model, Western blotting, in vivo ubiquitination assay, genetic epistasis (KLHL22 knockdown rescuing UBE4B-deletion phenotype), rapamycin rescue experiments","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis (KLHL22 knockdown reversal), in vivo ubiquitination assay, conditional KO mouse with defined neurogenesis phenotype, multiple orthogonal methods in one rigorous study","pmids":["36440598"],"is_preprint":false},{"year":2025,"finding":"KLHL22 is the E3 ubiquitin ligase responsible for K48-linked ubiquitination and degradation of SARS-CoV-2 NSP6, restoring intracellular calcium homeostasis and reversing NSP6-induced autophagic cell death.","method":"Co-immunoprecipitation identifying KLHL22–NSP6 interaction, ubiquitination assay demonstrating K48-linked ubiquitination, genetic knockdown/overexpression functional assays, calcium level measurements","journal":"Journal of advanced research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP and K48-linked ubiquitination shown, functional rescue demonstrated, single lab with multiple methods but not yet replicated","pmids":["40373961"],"is_preprint":false},{"year":2025,"finding":"In hepatocellular carcinoma, KLHL22 accumulates when UBE4B is deleted (consistent with UBE4B-mediated degradation of KLHL22); elevated KLHL22 drives resistance to BET inhibitors through a JAK2-PIM1 axis involving downregulation of the JAK2 negative regulator LNK.","method":"UBE4B siRNA silencing in HCC cells, KLHL22 knockdown epistasis experiment, Western blotting for JAK2/PIM1/LNK, BETi sensitivity assays","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Weak — epistasis (KLHL22 KD restoring BETi sensitivity), pathway component western blots, single lab, single study without replication","pmids":["40228637"],"is_preprint":false},{"year":2020,"finding":"KLHL22 knockdown in colorectal cancer cells activates the Wnt/β-catenin signaling pathway, partially via regulation of GSK-3β activity and PI3K levels, promoting epithelial-to-mesenchymal transition (EMT) and proliferation.","method":"Transwell invasion, MTT assay, Western blotting for Wnt/β-catenin pathway components, xenograft tumor model","journal":"Cancer management and research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — pathway changes inferred from Western blotting after KLHL22 knockdown, no direct substrate ubiquitination or binding shown, single lab","pmids":["32547233"],"is_preprint":false}],"current_model":"KLHL22 functions as a substrate adaptor for the CUL3 E3 ubiquitin ligase complex, promoting K48-linked polyubiquitination and proteasomal degradation of multiple substrates including DEPDC5 (activating mTORC1 via GATOR1 inactivation), PD-1 (maintaining T cell homeostasis), PLK1 (mitotic regulation), and SARS-CoV-2 NSP6; KLHL22 is itself regulated by UBE4B-mediated polyubiquitination and degradation, placing it within a UBE4B–KLHL22–DEPDC5–mTORC1 cascade critical for brain development and cell growth."},"narrative":{"mechanistic_narrative":"KLHL22 is a BTB-KELCH substrate adaptor for the CUL3 E3 ubiquitin ligase complex that directs K48-linked polyubiquitination and proteasomal degradation of diverse substrates to control cell growth, mitosis, immune homeostasis, and antiviral defense [PMID:29769719, PMID:24067371]. Its best-characterized role is nutrient-responsive activation of mTORC1: upon amino acid stimulation, CUL3-KLHL22 ubiquitinates and degrades DEPDC5, a subunit of the GATOR1 complex, relieving GATOR1-mediated inhibition of Rag GTPases and switching on mTORC1 signaling [PMID:29769719]. KLHL22 abundance is itself set by UBE4B, which polyubiquitylates and degrades KLHL22; loss of UBE4B raises KLHL22 levels, accelerating DEPDC5 turnover and hyperactivating mTOR, an axis that governs neural precursor proliferation and differentiation during brain development [PMID:36440598]. KLHL22 also targets the mitotic kinase PLK1 through bivalent recognition of two motifs independent of PLK1 catalytic activity [PMID:24067371], and limits cell-surface delivery of the immune checkpoint receptor PD-1 by degrading it prior to transport, thereby restraining excessive T cell suppression [PMID:33109719]. In an antiviral context, KLHL22 mediates K48-linked degradation of SARS-CoV-2 NSP6, restoring calcium homeostasis and reversing NSP6-induced autophagic cell death [PMID:40373961].","teleology":[{"year":2013,"claim":"Established KLHL22 as a bona fide CUL3 substrate adaptor by identifying its first substrate, defining how it recognizes targets independent of their enzymatic state.","evidence":"Co-IP, kinase-dead PLK1 mutant analysis, and mapping of two distinct interaction motifs within PLK1","pmids":["24067371"],"confidence":"Medium","gaps":["Functional consequence of PLK1 ubiquitination for mitotic progression not resolved","Single lab, no in vivo validation"]},{"year":2018,"claim":"Connected KLHL22 to nutrient sensing by showing it degrades DEPDC5 to activate mTORC1, placing the adaptor upstream of a central growth-control hub.","evidence":"Biochemical K48-linked ubiquitination assays, Co-IP, genetic depletion in mammalian cells and C. elegans, xenograft models","pmids":["29769719"],"confidence":"High","gaps":["Mechanism linking amino acid availability to KLHL22 activation not fully defined","Subcellular site of DEPDC5 degradation unresolved"]},{"year":2020,"claim":"Extended KLHL22 substrate range to immune regulation by demonstrating it degrades PD-1 before surface transport, defining a checkpoint-receptor homeostatic control.","evidence":"Reciprocal Co-IP, KLHL22 loss-of-function causing PD-1 overaccumulation, functional T cell assays","pmids":["33109719"],"confidence":"High","gaps":["Trafficking step at which degradation occurs not precisely mapped","In vivo immune phenotype of KLHL22 loss not characterized"]},{"year":2022,"claim":"Resolved how KLHL22 itself is regulated, showing UBE4B degrades KLHL22 and that this UBE4B-KLHL22-DEPDC5-mTOR cascade governs neurogenesis.","evidence":"Conditional UBE4B knockout mouse, in vivo ubiquitination assay, genetic epistasis (KLHL22 knockdown rescue), rapamycin rescue","pmids":["36440598"],"confidence":"High","gaps":["Whether UBE4B regulates KLHL22's non-DEPDC5 substrates not addressed","Direct biochemical UBE4B-KLHL22 contact not detailed"]},{"year":2025,"claim":"Implicated KLHL22 in antiviral defense by identifying SARS-CoV-2 NSP6 as a substrate whose degradation restores calcium homeostasis.","evidence":"Co-IP, K48-linked ubiquitination assay, knockdown/overexpression functional assays, calcium measurements","pmids":["40373961"],"confidence":"Medium","gaps":["Not independently replicated","Physiological relevance during authentic infection not established"]},{"year":2025,"claim":"Linked KLHL22 accumulation to therapy resistance in hepatocellular carcinoma, connecting its dysregulation to a JAK2-PIM1 oncogenic axis.","evidence":"UBE4B siRNA silencing in HCC cells, KLHL22 knockdown epistasis, Western blotting for JAK2/PIM1/LNK, BET inhibitor sensitivity assays","pmids":["40228637"],"confidence":"Medium","gaps":["Direct KLHL22 substrate driving JAK2-PIM1 changes not identified","Single study without replication"]},{"year":null,"claim":"The full substrate repertoire of CUL3-KLHL22 and the signals that switch its activity across tissues remain incompletely defined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of substrate recognition reported","Tissue-specific regulation of adaptor activity unmapped","Whether reported cancer phenotypes reflect direct substrate degradation unproven for some studies"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2,4]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[0,4]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2]}],"localization":[],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,1,2,4]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,3]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1]}],"complexes":["CUL3-KLHL22 E3 ubiquitin ligase"],"partners":["CUL3","DEPDC5","PDCD1","PLK1","UBE4B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q53GT1","full_name":"Kelch-like protein 22","aliases":[],"length_aa":634,"mass_kda":71.7,"function":"Substrate-specific adapter of a BCR (BTB-CUL3-RBX1) E3 ubiquitin ligase complex required for chromosome alignment and localization of PLK1 at kinetochores. The BCR(KLHL22) ubiquitin ligase complex mediates monoubiquitination of PLK1, leading to PLK1 dissociation from phosphoreceptor proteins and subsequent removal from kinetochores, allowing silencing of the spindle assembly checkpoint (SAC) and chromosome segregation. Monoubiquitination of PLK1 does not lead to PLK1 degradation (PubMed:19995937, PubMed:23455478). The BCR(KLHL22) ubiquitin ligase complex is also responsible for the amino acid-stimulated 'Lys-48' polyubiquitination and proteasomal degradation of DEPDC5. Through the degradation of DEPDC5, releases the GATOR1 complex-mediated inhibition of the TORC1 pathway. It is therefore an amino acid-dependent activator within the amino acid-sensing branch of the TORC1 pathway, indirectly regulating different cellular processes including cell growth and autophagy (PubMed:29769719)","subcellular_location":"Cytoplasm, cytosol; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Cytoplasm, cytoskeleton, spindle; Nucleus; Lysosome","url":"https://www.uniprot.org/uniprotkb/Q53GT1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KLHL22","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KLHL22","total_profiled":1310},"omim":[{"mim_id":"618020","title":"KELCH-LIKE 22; KLHL22","url":"https://www.omim.org/entry/618020"},{"mim_id":"616262","title":"KELCH-LIKE 21; KLHL21","url":"https://www.omim.org/entry/616262"},{"mim_id":"614191","title":"DEP DOMAIN-CONTAINING PROTEIN 5; DEPDC5","url":"https://www.omim.org/entry/614191"},{"mim_id":"603136","title":"CULLIN 3; CUL3","url":"https://www.omim.org/entry/603136"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Vesicles","reliability":"Supported"},{"location":"Microtubules","reliability":"Supported"},{"location":"Cytokinetic bridge","reliability":"Supported"},{"location":"Mitotic spindle","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/KLHL22"},"hgnc":{"alias_symbol":["FLJ14360","KELCHL"],"prev_symbol":[]},"alphafold":{"accession":"Q53GT1","domains":[{"cath_id":"3.30.710.10","chopping":"34-146","consensus_level":"high","plddt":94.547,"start":34,"end":146},{"cath_id":"1.25.40.420","chopping":"185-284","consensus_level":"medium","plddt":94.8488,"start":185,"end":284},{"cath_id":"2.120.10.80","chopping":"297-596","consensus_level":"high","plddt":95.1327,"start":297,"end":596}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q53GT1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q53GT1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q53GT1-F1-predicted_aligned_error_v6.png","plddt_mean":89.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KLHL22","jax_strain_url":"https://www.jax.org/strain/search?query=KLHL22"},"sequence":{"accession":"Q53GT1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q53GT1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q53GT1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q53GT1"}},"corpus_meta":[{"pmid":"29769719","id":"PMC_29769719","title":"KLHL22 activates amino-acid-dependent mTORC1 signalling to promote tumorigenesis and ageing.","date":"2018","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/29769719","citation_count":110,"is_preprint":false},{"pmid":"33109719","id":"PMC_33109719","title":"KLHL22 maintains PD-1 homeostasis and prevents excessive T cell suppression.","date":"2020","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/33109719","citation_count":70,"is_preprint":false},{"pmid":"24067371","id":"PMC_24067371","title":"CUL3 and protein kinases: insights from PLK1/KLHL22 interaction.","date":"2013","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/24067371","citation_count":19,"is_preprint":false},{"pmid":"32547233","id":"PMC_32547233","title":"KLHL22 Regulates the EMT and Proliferation in Colorectal Cancer Cells in Part via the Wnt/β-Catenin Signaling Pathway.","date":"2020","source":"Cancer management and research","url":"https://pubmed.ncbi.nlm.nih.gov/32547233","citation_count":15,"is_preprint":false},{"pmid":"36440598","id":"PMC_36440598","title":"Fine-tuning of mTOR signaling by the UBE4B-KLHL22 E3 ubiquitin ligase cascade in brain development.","date":"2022","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/36440598","citation_count":7,"is_preprint":false},{"pmid":"32484697","id":"PMC_32484697","title":"KLHL22 promotes malignant melanoma growth in vitro and in vivo by activating the PI3K/Akt/mTOR signaling pathway.","date":"2020","source":"Neoplasma","url":"https://pubmed.ncbi.nlm.nih.gov/32484697","citation_count":6,"is_preprint":false},{"pmid":"40373961","id":"PMC_40373961","title":"NSP6 regulates calcium overload-induced autophagic cell death and is regulated by KLHL22-mediated ubiquitination.","date":"2025","source":"Journal of advanced research","url":"https://pubmed.ncbi.nlm.nih.gov/40373961","citation_count":2,"is_preprint":false},{"pmid":"40228637","id":"PMC_40228637","title":"UBE4B modulates BET inhibitor sensitivity via KLHL22-JAK2-PIM1 axis in hepatocellular carcinoma.","date":"2025","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/40228637","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.10.28.24314051","title":"Extremely rare CNVs contributing to Alzheimer disease risk: a case-control association analysis of exome sequencing data from 22,319 individuals","date":"2024-11-01","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.28.24314051","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7000,"output_tokens":1960,"usd":0.0252,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8894,"output_tokens":2531,"usd":0.053872,"stage2_stop_reason":"end_turn"},"total_usd":0.079072,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"In response to amino acids, CUL3-KLHL22 E3 ubiquitin ligase promotes K48-linked polyubiquitination and degradation of DEPDC5 (an essential subunit of the GATOR1 complex), thereby releasing GATOR1-mediated inhibition of Rag GTPases and activating mTORC1 signaling.\",\n      \"method\": \"Biochemical ubiquitination assays, co-immunoprecipitation, Western blotting, genetic depletion in mammalian cells and C. elegans, xenograft tumor models\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — K48-linked ubiquitination demonstrated biochemically, substrate (DEPDC5) identified with Co-IP, conserved function validated in nematode, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"29769719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"KLHL22, acting as an adaptor of the CUL3-based E3 ligase complex, mediates K48-linked ubiquitination and degradation of PD-1 before its transport to the cell surface, thereby maintaining PD-1 homeostasis and preventing excessive T cell suppression.\",\n      \"method\": \"Co-immunoprecipitation identifying KLHL22 as a major PD-1-associated protein, genetic depletion (KLHL22 deficiency) leading to PD-1 overaccumulation, Western blotting, functional T cell assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP identifying KLHL22–PD-1 interaction, loss-of-function phenotype (PD-1 overaccumulation), functional T cell assays, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"33109719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"KLHL22 serves as the BTB-KELCH adaptor in a CUL3 E3-ligase complex that targets the mitotic kinase PLK1 for ubiquitination; PLK1 kinase activity is dispensable for its targeting, and CUL3/KLHL22 contacts two distinct motifs within PLK1, consistent with a bivalent mode of substrate targeting.\",\n      \"method\": \"Co-immunoprecipitation, kinase-dead PLK1 mutant analysis, mapping of interaction motifs within PLK1\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct binding and ubiquitination established with mutant PLK1 and motif mapping, single lab, mechanistic follow-up study\",\n      \"pmids\": [\"24067371\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"UBE4B polyubiquitylates and degrades KLHL22; loss of UBE4B causes upregulation of KLHL22 protein levels, which in turn increases DEPDC5 degradation and hyperactivates mTOR, leading to defective neural precursor cell proliferation and differentiation. Suppression of KLHL22 reverses mTOR hyperactivation caused by UBE4B deletion.\",\n      \"method\": \"Conditional UBE4B knockout mouse model, Western blotting, in vivo ubiquitination assay, genetic epistasis (KLHL22 knockdown rescuing UBE4B-deletion phenotype), rapamycin rescue experiments\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis (KLHL22 knockdown reversal), in vivo ubiquitination assay, conditional KO mouse with defined neurogenesis phenotype, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"36440598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"KLHL22 is the E3 ubiquitin ligase responsible for K48-linked ubiquitination and degradation of SARS-CoV-2 NSP6, restoring intracellular calcium homeostasis and reversing NSP6-induced autophagic cell death.\",\n      \"method\": \"Co-immunoprecipitation identifying KLHL22–NSP6 interaction, ubiquitination assay demonstrating K48-linked ubiquitination, genetic knockdown/overexpression functional assays, calcium level measurements\",\n      \"journal\": \"Journal of advanced research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP and K48-linked ubiquitination shown, functional rescue demonstrated, single lab with multiple methods but not yet replicated\",\n      \"pmids\": [\"40373961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In hepatocellular carcinoma, KLHL22 accumulates when UBE4B is deleted (consistent with UBE4B-mediated degradation of KLHL22); elevated KLHL22 drives resistance to BET inhibitors through a JAK2-PIM1 axis involving downregulation of the JAK2 negative regulator LNK.\",\n      \"method\": \"UBE4B siRNA silencing in HCC cells, KLHL22 knockdown epistasis experiment, Western blotting for JAK2/PIM1/LNK, BETi sensitivity assays\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Weak — epistasis (KLHL22 KD restoring BETi sensitivity), pathway component western blots, single lab, single study without replication\",\n      \"pmids\": [\"40228637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"KLHL22 knockdown in colorectal cancer cells activates the Wnt/β-catenin signaling pathway, partially via regulation of GSK-3β activity and PI3K levels, promoting epithelial-to-mesenchymal transition (EMT) and proliferation.\",\n      \"method\": \"Transwell invasion, MTT assay, Western blotting for Wnt/β-catenin pathway components, xenograft tumor model\",\n      \"journal\": \"Cancer management and research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — pathway changes inferred from Western blotting after KLHL22 knockdown, no direct substrate ubiquitination or binding shown, single lab\",\n      \"pmids\": [\"32547233\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KLHL22 functions as a substrate adaptor for the CUL3 E3 ubiquitin ligase complex, promoting K48-linked polyubiquitination and proteasomal degradation of multiple substrates including DEPDC5 (activating mTORC1 via GATOR1 inactivation), PD-1 (maintaining T cell homeostasis), PLK1 (mitotic regulation), and SARS-CoV-2 NSP6; KLHL22 is itself regulated by UBE4B-mediated polyubiquitination and degradation, placing it within a UBE4B–KLHL22–DEPDC5–mTORC1 cascade critical for brain development and cell growth.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KLHL22 is a BTB-KELCH substrate adaptor for the CUL3 E3 ubiquitin ligase complex that directs K48-linked polyubiquitination and proteasomal degradation of diverse substrates to control cell growth, mitosis, immune homeostasis, and antiviral defense [#0, #2]. Its best-characterized role is nutrient-responsive activation of mTORC1: upon amino acid stimulation, CUL3-KLHL22 ubiquitinates and degrades DEPDC5, a subunit of the GATOR1 complex, relieving GATOR1-mediated inhibition of Rag GTPases and switching on mTORC1 signaling [#0]. KLHL22 abundance is itself set by UBE4B, which polyubiquitylates and degrades KLHL22; loss of UBE4B raises KLHL22 levels, accelerating DEPDC5 turnover and hyperactivating mTOR, an axis that governs neural precursor proliferation and differentiation during brain development [#3]. KLHL22 also targets the mitotic kinase PLK1 through bivalent recognition of two motifs independent of PLK1 catalytic activity [#2], and limits cell-surface delivery of the immune checkpoint receptor PD-1 by degrading it prior to transport, thereby restraining excessive T cell suppression [#1]. In an antiviral context, KLHL22 mediates K48-linked degradation of SARS-CoV-2 NSP6, restoring calcium homeostasis and reversing NSP6-induced autophagic cell death [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established KLHL22 as a bona fide CUL3 substrate adaptor by identifying its first substrate, defining how it recognizes targets independent of their enzymatic state.\",\n      \"evidence\": \"Co-IP, kinase-dead PLK1 mutant analysis, and mapping of two distinct interaction motifs within PLK1\",\n      \"pmids\": [\"24067371\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional consequence of PLK1 ubiquitination for mitotic progression not resolved\", \"Single lab, no in vivo validation\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected KLHL22 to nutrient sensing by showing it degrades DEPDC5 to activate mTORC1, placing the adaptor upstream of a central growth-control hub.\",\n      \"evidence\": \"Biochemical K48-linked ubiquitination assays, Co-IP, genetic depletion in mammalian cells and C. elegans, xenograft models\",\n      \"pmids\": [\"29769719\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Mechanism linking amino acid availability to KLHL22 activation not fully defined\", \"Subcellular site of DEPDC5 degradation unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended KLHL22 substrate range to immune regulation by demonstrating it degrades PD-1 before surface transport, defining a checkpoint-receptor homeostatic control.\",\n      \"evidence\": \"Reciprocal Co-IP, KLHL22 loss-of-function causing PD-1 overaccumulation, functional T cell assays\",\n      \"pmids\": [\"33109719\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Trafficking step at which degradation occurs not precisely mapped\", \"In vivo immune phenotype of KLHL22 loss not characterized\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolved how KLHL22 itself is regulated, showing UBE4B degrades KLHL22 and that this UBE4B-KLHL22-DEPDC5-mTOR cascade governs neurogenesis.\",\n      \"evidence\": \"Conditional UBE4B knockout mouse, in vivo ubiquitination assay, genetic epistasis (KLHL22 knockdown rescue), rapamycin rescue\",\n      \"pmids\": [\"36440598\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether UBE4B regulates KLHL22's non-DEPDC5 substrates not addressed\", \"Direct biochemical UBE4B-KLHL22 contact not detailed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Implicated KLHL22 in antiviral defense by identifying SARS-CoV-2 NSP6 as a substrate whose degradation restores calcium homeostasis.\",\n      \"evidence\": \"Co-IP, K48-linked ubiquitination assay, knockdown/overexpression functional assays, calcium measurements\",\n      \"pmids\": [\"40373961\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Not independently replicated\", \"Physiological relevance during authentic infection not established\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked KLHL22 accumulation to therapy resistance in hepatocellular carcinoma, connecting its dysregulation to a JAK2-PIM1 oncogenic axis.\",\n      \"evidence\": \"UBE4B siRNA silencing in HCC cells, KLHL22 knockdown epistasis, Western blotting for JAK2/PIM1/LNK, BET inhibitor sensitivity assays\",\n      \"pmids\": [\"40228637\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct KLHL22 substrate driving JAK2-PIM1 changes not identified\", \"Single study without replication\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The full substrate repertoire of CUL3-KLHL22 and the signals that switch its activity across tissues remain incompletely defined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No structural model of substrate recognition reported\", \"Tissue-specific regulation of adaptor activity unmapped\", \"Whether reported cancer phenotypes reflect direct substrate degradation unproven for some studies\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 4]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 2, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\"CUL3-KLHL22 E3 ubiquitin ligase\"],\n    \"partners\": [\"CUL3\", \"DEPDC5\", \"PDCD1\", \"PLK1\", \"UBE4B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}