{"gene":"KCTD7","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2011,"finding":"KCTD7 expression hyperpolarizes the cell membrane and reduces the excitability of transfected neurons, as measured by patch clamp experiments, indicating KCTD7 is a regulator of potassium conductance in neurons.","method":"Patch clamp electrophysiology in transfected neurons; co-immunoprecipitation","journal":"Molecular neurobiology","confidence":"High","confidence_rationale":"Tier 1-2 — direct electrophysiological assay in neurons plus Co-IP, single lab with two orthogonal methods","pmids":["21710140"],"is_preprint":false},{"year":2011,"finding":"KCTD7 directly interacts with Cullin-3 (a ubiquitin-ligase component), as demonstrated by co-immunoprecipitation, suggesting the effect of KCTD7 on membrane resting potential is mediated through Cullin-3.","method":"Co-immunoprecipitation","journal":"Molecular neurobiology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP replicated in multiple subsequent studies","pmids":["21710140","22748208"],"is_preprint":false},{"year":2012,"finding":"The KCTD7 p.Arg184Cys patient mutation alters the subcellular localization pattern of KCTD7 and abrogates its interaction with Cullin-3, linking this loss of Cullin-3 interaction to NCL pathogenesis.","method":"Cell-based localization assay; co-immunoprecipitation with patient-derived mutant","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2-3 — functional cell-based assay with patient mutation, single lab","pmids":["22748208"],"is_preprint":false},{"year":2012,"finding":"KCTD7 shows cytosolic localization and predominant neuronal expression throughout the mouse brain; patient missense mutations do not affect subcellular distribution of KCTD7.","method":"Immunofluorescence in cellular cultures and mouse brain tissue","journal":"Journal of medical genetics","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization experiment, replicated across labs, but functional consequence of localization not directly tested here","pmids":["22693283"],"is_preprint":false},{"year":2016,"finding":"Wild-type KCTD7 expressed in Xenopus laevis oocytes hyperpolarizes cells in a K+-dependent manner and regulates activity of the neuronal glutamine transporter SAT2 (Slc38a2); the frameshift variant F232fs impairs K+ fluxes and obliterates SAT2-dependent glutamine transport. Four additional disease-causing variants (R94W, R184C, N273I, Y276C) also impair these functions.","method":"Heterologous expression in Xenopus oocytes; electrophysiology; glutamine transport assays; structure modeling","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 1 — reconstitution in Xenopus oocytes with multiple patient variants tested, two orthogonal functional readouts (K+ flux and glutamine transport)","pmids":["27742667"],"is_preprint":false},{"year":2018,"finding":"Patient-derived fibroblasts with KCTD7 mutations and yeast lacking Whi2 (a KCTD7 sequence-similar protein) show impaired autophagy, establishing a conserved autophagy-lysosome defect as a disease mechanism in KCTD7 deficiency.","method":"Cell-based functional assays of patient fibroblasts; knockout yeast; electron microscopy","journal":"Annals of neurology","confidence":"Medium","confidence_rationale":"Tier 2 — patient fibroblasts plus yeast model, two orthogonal model systems, single lab","pmids":["30295347"],"is_preprint":false},{"year":2022,"finding":"The CRL3-KCTD7 E3 ubiquitin ligase complex (comprising CUL3, KCTD7, and Rbx1) targets CLN5 for ubiquitination and proteasomal degradation; patient KCTD7 mutations disrupt KCTD7-CUL3 or KCTD7-CLN5 interactions, causing CLN5 accumulation in the ER, which impairs CLN6/8-mediated ER-to-Golgi trafficking of lysosomal enzymes.","method":"Co-immunoprecipitation; ubiquitination assays; KCTD7-deficient cell lines; ER trafficking assays; protein interaction studies with patient-derived variants","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal biochemical assays including ubiquitination, Co-IP, and trafficking studies; identifies substrate and downstream pathway mechanism","pmids":["35921411"],"is_preprint":false},{"year":2023,"finding":"KCTD7 works in complex with Cullin-3 and Rbx1 to execute non-degradative ubiquitination of calpain 1 (at K398) and calpain 2 (at K280 and K674); KCTD7 mediates K6-, K27-, K29-, and K63-linked ubiquitin chains on calpain 1 and K6-linked chains on calpain 2. Loss of this ubiquitination leads to calpain hyperactivation, aberrant substrate cleavage, and caspase-3 activation. CRISPR/Cas9 Kctd7 knockout mice recapitulate human disease and calpain inhibition largely prevents neurodegeneration.","method":"In vitro ubiquitination assays; single-lysine ubiquitin mutants; co-immunoprecipitation; CRISPR/Cas9 mouse knockout; pharmacological calpain inhibition; behavioral and neuropathological analysis","journal":"Cell discovery","confidence":"High","confidence_rationale":"Tier 1 — reconstituted ubiquitination with site-specific mutants, in vivo knockout rescue by pharmacological inhibition, multiple orthogonal methods","pmids":["36964131"],"is_preprint":false},{"year":2019,"finding":"Kctd7 is expressed in inner retina neurons (not vessels) and its deletion in mice induces defective retinal vascular patterning (increased branching, vessel length, lacunarity) and delays emergence of superficial and deep vascular layers, accompanied by increased bipolar cell number and retinal function deficits, demonstrating neuronal Kctd7 drives neurovascular patterning.","method":"Kctd7 conditional mouse knockout; retinal immunohistochemistry; retinal vessel imaging; ERG functional assessment","journal":"Neurochemistry international","confidence":"Medium","confidence_rationale":"Tier 2 — clean knockout with specific cellular and vascular phenotypic readouts, single lab","pmids":["31175897"],"is_preprint":false},{"year":2022,"finding":"Kctd7-deficient mice develop myoclonic seizures, locomotor defects, Purkinje cell degeneration in the cerebellum, and cerebellar microvascular disorganization, establishing Kctd7 as required for Purkinje cell survival and modulator of neuron excitability linked to microvascular integrity.","method":"Kctd7 knockout mouse; EEG seizure monitoring; histological analysis; immunofluorescence; behavioral testing","journal":"Disease models & mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO mouse with defined cellular (Purkinje cell death) and circuit (seizure) phenotypes, single lab","pmids":["35972048"],"is_preprint":false},{"year":2021,"finding":"Whole-cell patch-clamp analysis of neuroblastoma cells overexpressing patient KCTD7 variant alleles demonstrated aberrant potassium regulation, and kctd7 knockout zebrafish showed global dysregulation of gene expression and increased c-fos transcription (a seizure activity marker).","method":"Patch-clamp electrophysiology; zinc finger nuclease zebrafish knockout; RNA-seq","journal":"Journal of neurogenetics","confidence":"Medium","confidence_rationale":"Tier 2 — electrophysiology with patient variants plus zebrafish KO model, two orthogonal systems","pmids":["33970744"],"is_preprint":false}],"current_model":"KCTD7 functions as a substrate-binding adaptor for the CUL3-RBX1 E3 ubiquitin ligase complex, mediating non-degradative ubiquitination of calpains (suppressing their hyperactivation) and degradative ubiquitination of CLN5 (maintaining lysosomal enzyme trafficking from ER to Golgi); it also regulates neuronal potassium conductance and membrane hyperpolarization and modulates glutamine transporter SAT2 activity, with loss of any of these functions resulting in progressive myoclonic epilepsy and neurodegeneration."},"narrative":{"teleology":[{"year":2011,"claim":"Establishing that KCTD7 regulates neuronal excitability answered the question of how loss-of-function mutations cause epilepsy: KCTD7 expression hyperpolarizes neurons via potassium conductance and physically interacts with Cullin-3.","evidence":"Patch-clamp electrophysiology in transfected neurons; co-immunoprecipitation","pmids":["21710140"],"confidence":"High","gaps":["Identity of the potassium channel(s) directly modulated by KCTD7 remains unknown","Mechanism linking CUL3 interaction to potassium conductance was not established"]},{"year":2012,"claim":"Demonstrating that the patient R184C mutation abrogates CUL3 binding while KCTD7 localizes to the cytosol of neurons established that disrupted CUL3 interaction is a direct disease mechanism.","evidence":"Co-immunoprecipitation with patient mutant; immunofluorescence in cells and mouse brain","pmids":["22748208","22693283"],"confidence":"Medium","gaps":["How loss of CUL3 binding mechanistically leads to neurodegeneration was not resolved","Different subcellular localization findings between two labs not fully reconciled"]},{"year":2016,"claim":"Reconstitution in Xenopus oocytes revealed that KCTD7 drives K⁺-dependent hyperpolarization and regulates the glutamine transporter SAT2, broadening the functional scope beyond ion channels to amino acid transport — with multiple patient variants ablating both functions.","evidence":"Heterologous expression in Xenopus oocytes; electrophysiology; glutamine transport assays with five patient variants","pmids":["27742667"],"confidence":"High","gaps":["Whether SAT2 regulation is direct or secondary to membrane potential changes was not resolved","Relevance of glutamine transport deficiency to neurodegeneration in vivo was not tested"]},{"year":2018,"claim":"Patient fibroblasts and yeast lacking KCTD7-homolog Whi2 revealed impaired autophagy, establishing a conserved autophagy-lysosome axis as a disease mechanism.","evidence":"Cell-based autophagy assays in patient fibroblasts; yeast Whi2 knockout; electron microscopy","pmids":["30295347"],"confidence":"Medium","gaps":["Molecular target through which KCTD7 controls autophagy was not identified","Yeast Whi2 functional equivalence to human KCTD7 not rigorously demonstrated"]},{"year":2019,"claim":"Kctd7 knockout mice revealed that neuronal KCTD7 non-cell-autonomously drives retinal vascular patterning and deep layer formation, extending its roles beyond excitability to neurovascular development.","evidence":"Conditional Kctd7 mouse knockout; retinal immunohistochemistry; vessel imaging; ERG","pmids":["31175897"],"confidence":"Medium","gaps":["Signaling intermediates between neuronal KCTD7 and vascular patterning are unknown","Single lab finding; independent replication lacking"]},{"year":2021,"claim":"Patient KCTD7 variants confirmed to impair potassium regulation by patch clamp, and kctd7 knockout zebrafish showed global transcriptional dysregulation and elevated seizure marker c-fos, validating the excitability phenotype across species.","evidence":"Patch-clamp in neuroblastoma cells; zinc-finger nuclease zebrafish knockout; RNA-seq","pmids":["33970744"],"confidence":"Medium","gaps":["Direct target genes versus secondary transcriptional changes not distinguished","Zebrafish phenotype not deeply characterized at the cellular or circuit level"]},{"year":2022,"claim":"Two key advances resolved KCTD7's dual ubiquitin ligase substrates and in vivo neurodegeneration: CRL3-KCTD7 ubiquitinates CLN5 for proteasomal degradation to maintain ER-to-Golgi lysosomal enzyme trafficking, and Kctd7 KO mice develop myoclonic seizures and Purkinje cell degeneration.","evidence":"Ubiquitination assays and ER trafficking studies in KCTD7-deficient cells; Kctd7 KO mouse with EEG and histology","pmids":["35921411","35972048"],"confidence":"High","gaps":["Whether CLN5 accumulation alone is sufficient to cause neurodegeneration was not tested","Relationship between Purkinje cell death and cerebellar microvascular disorganization is correlative"]},{"year":2023,"claim":"Identification of calpains 1 and 2 as non-degradative ubiquitination substrates of CRL3-KCTD7, with specific lysine sites and chain types mapped, established that calpain hyperactivation is a central neurodegenerative mechanism — validated by pharmacological rescue in KO mice.","evidence":"In vitro ubiquitination with single-lysine ubiquitin mutants; CRISPR Kctd7 KO mouse; calpain inhibitor rescue; behavioral and neuropathological analysis","pmids":["36964131"],"confidence":"High","gaps":["Relative contributions of calpain hyperactivation versus CLN5 accumulation to disease remain unclear","Whether non-degradative ubiquitination of calpains suppresses activity directly or via altered localization is not determined"]},{"year":null,"claim":"The identity of the potassium channel(s) directly modulated by KCTD7, the mechanistic link between K⁺ conductance and CUL3-mediated ubiquitination, and the relative pathogenic contribution of each substrate arm (calpain versus CLN5 versus SAT2) remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No potassium channel subunit has been identified as a direct KCTD7 binding partner","Whether CUL3-dependent and K⁺-conductance functions are mechanistically coupled or independent is unknown","Therapeutic relevance of calpain inhibition in human patients not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[6,7]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2,6,7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,4]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[6,7]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,4,9]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[6]}],"complexes":["CRL3-KCTD7 (CUL3-KCTD7-RBX1)"],"partners":["CUL3","RBX1","CLN5","CAPN1","CAPN2","SLC38A2"],"other_free_text":[]},"mechanistic_narrative":"KCTD7 is a neuronal potassium conductance regulator and CUL3-RBX1 E3 ubiquitin ligase adaptor whose loss causes progressive myoclonic epilepsy and neuronal ceroid lipofuscinosis. It hyperpolarizes neuronal membranes in a K⁺-dependent manner and modulates the glutamine transporter SAT2 (SLC38A2), with disease-causing mutations impairing both K⁺ flux and SAT2-mediated glutamine transport [PMID:21710140, PMID:27742667]. As a substrate adaptor within the CRL3-KCTD7 complex, it directs non-degradative (K6/K27/K29/K63-linked) ubiquitination of calpains 1 and 2 to suppress their hyperactivation, and degradative ubiquitination of CLN5 to maintain CLN6/8-dependent ER-to-Golgi trafficking of lysosomal enzymes [PMID:35921411, PMID:36964131]. Kctd7 knockout mice develop myoclonic seizures, Purkinje cell degeneration, retinal neurovascular patterning defects, and calpain-driven neurodegeneration that is largely rescued by calpain inhibition [PMID:36964131, PMID:35972048, PMID:31175897]."},"prefetch_data":{"uniprot":{"accession":"Q96MP8","full_name":"BTB/POZ domain-containing protein KCTD7","aliases":[],"length_aa":289,"mass_kda":33.1,"function":"May be involved in the control of excitability of cortical neurons","subcellular_location":"Cell membrane; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q96MP8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCTD7","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1208,"dependency_fraction":0.0041390728476821195},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KCTD7","total_profiled":1310},"omim":[{"mim_id":"611726","title":"EPILEPSY, PROGRESSIVE MYOCLONIC, 3, WITH OR WITHOUT INTRACELLULAR INCLUSIONS; EPM3","url":"https://www.omim.org/entry/611726"},{"mim_id":"611725","title":"POTASSIUM CHANNEL TETRAMERIZATION DOMAIN-CONTAINING PROTEIN 7; KCTD7","url":"https://www.omim.org/entry/611725"},{"mim_id":"256730","title":"CEROID LIPOFUSCINOSIS, NEURONAL, 1; CLN1","url":"https://www.omim.org/entry/256730"},{"mim_id":"254800","title":"MYOCLONIC EPILEPSY OF UNVERRICHT AND LUNDBORG","url":"https://www.omim.org/entry/254800"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"retina","ntpm":60.9}],"url":"https://www.proteinatlas.org/search/KCTD7"},"hgnc":{"alias_symbol":["FLJ32069","EPM3","CLN14"],"prev_symbol":[]},"alphafold":{"accession":"Q96MP8","domains":[{"cath_id":"3.30.710.10","chopping":"51-144","consensus_level":"high","plddt":96.0824,"start":51,"end":144},{"cath_id":"-","chopping":"156-199_225-286","consensus_level":"high","plddt":89.688,"start":156,"end":286}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96MP8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96MP8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96MP8-F1-predicted_aligned_error_v6.png","plddt_mean":81.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCTD7","jax_strain_url":"https://www.jax.org/strain/search?query=KCTD7"},"sequence":{"accession":"Q96MP8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96MP8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96MP8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96MP8"}},"corpus_meta":[{"pmid":"22748208","id":"PMC_22748208","title":"A homozygous mutation in KCTD7 links neuronal ceroid lipofuscinosis to the ubiquitin-proteasome system.","date":"2012","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22748208","citation_count":89,"is_preprint":false},{"pmid":"22693283","id":"PMC_22693283","title":"Novel mutations consolidate KCTD7 as a progressive myoclonus epilepsy gene.","date":"2012","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22693283","citation_count":61,"is_preprint":false},{"pmid":"21710140","id":"PMC_21710140","title":"Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons.","date":"2011","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/21710140","citation_count":59,"is_preprint":false},{"pmid":"30295347","id":"PMC_30295347","title":"KCTD7 deficiency defines a distinct neurodegenerative disorder with a conserved autophagy-lysosome defect.","date":"2018","source":"Annals of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/30295347","citation_count":50,"is_preprint":false},{"pmid":"22638565","id":"PMC_22638565","title":"A compound heterozygous missense mutation and a large deletion in the KCTD7 gene presenting as an opsoclonus-myoclonus ataxia-like syndrome.","date":"2012","source":"Journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/22638565","citation_count":45,"is_preprint":false},{"pmid":"22606975","id":"PMC_22606975","title":"Novel mutation in potassium channel related gene KCTD7 and progressive myoclonic epilepsy.","date":"2012","source":"Annals of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22606975","citation_count":32,"is_preprint":false},{"pmid":"27742667","id":"PMC_27742667","title":"Pathogenic variants in KCTD7 perturb neuronal K+ fluxes and glutamine transport.","date":"2016","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/27742667","citation_count":30,"is_preprint":false},{"pmid":"25060828","id":"PMC_25060828","title":"Linkage analysis and exome sequencing identify a novel mutation in KCTD7 in patients with progressive myoclonus epilepsy with ataxia.","date":"2014","source":"Epilepsia","url":"https://pubmed.ncbi.nlm.nih.gov/25060828","citation_count":28,"is_preprint":false},{"pmid":"27629772","id":"PMC_27629772","title":"KCTD7-related progressive myoclonus epilepsy.","date":"2016","source":"Epileptic disorders : international epilepsy journal with videotape","url":"https://pubmed.ncbi.nlm.nih.gov/27629772","citation_count":24,"is_preprint":false},{"pmid":"35921411","id":"PMC_35921411","title":"KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses.","date":"2022","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/35921411","citation_count":22,"is_preprint":false},{"pmid":"30500434","id":"PMC_30500434","title":"Progressive myoclonus epilepsy and ceroidolipofuscinosis 14: The multifaceted phenotypic spectrum of KCTD7-related disorders.","date":"2018","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30500434","citation_count":18,"is_preprint":false},{"pmid":"36964131","id":"PMC_36964131","title":"Calpain activity is negatively regulated by a KCTD7-Cullin-3 complex via non-degradative ubiquitination.","date":"2023","source":"Cell discovery","url":"https://pubmed.ncbi.nlm.nih.gov/36964131","citation_count":11,"is_preprint":false},{"pmid":"38231304","id":"PMC_38231304","title":"KCTD7-related progressive myoclonic epilepsy: Report of 42 cases and review of 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reports","url":"https://pubmed.ncbi.nlm.nih.gov/40123863","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13119,"output_tokens":2567,"usd":0.038931},"stage2":{"model":"claude-opus-4-6","input_tokens":5895,"output_tokens":2520,"usd":0.138712},"total_usd":0.177643,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"KCTD7 expression hyperpolarizes the cell membrane and reduces the excitability of transfected neurons, as measured by patch clamp experiments, indicating KCTD7 is a regulator of potassium conductance in neurons.\",\n      \"method\": \"Patch clamp electrophysiology in transfected neurons; co-immunoprecipitation\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct electrophysiological assay in neurons plus Co-IP, single lab with two orthogonal methods\",\n      \"pmids\": [\"21710140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"KCTD7 directly interacts with Cullin-3 (a ubiquitin-ligase component), as demonstrated by co-immunoprecipitation, suggesting the effect of KCTD7 on membrane resting potential is mediated through Cullin-3.\",\n      \"method\": \"Co-immunoprecipitation\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP replicated in multiple subsequent studies\",\n      \"pmids\": [\"21710140\", \"22748208\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The KCTD7 p.Arg184Cys patient mutation alters the subcellular localization pattern of KCTD7 and abrogates its interaction with Cullin-3, linking this loss of Cullin-3 interaction to NCL pathogenesis.\",\n      \"method\": \"Cell-based localization assay; co-immunoprecipitation with patient-derived mutant\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — functional cell-based assay with patient mutation, single lab\",\n      \"pmids\": [\"22748208\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"KCTD7 shows cytosolic localization and predominant neuronal expression throughout the mouse brain; patient missense mutations do not affect subcellular distribution of KCTD7.\",\n      \"method\": \"Immunofluorescence in cellular cultures and mouse brain tissue\",\n      \"journal\": \"Journal of medical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiment, replicated across labs, but functional consequence of localization not directly tested here\",\n      \"pmids\": [\"22693283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Wild-type KCTD7 expressed in Xenopus laevis oocytes hyperpolarizes cells in a K+-dependent manner and regulates activity of the neuronal glutamine transporter SAT2 (Slc38a2); the frameshift variant F232fs impairs K+ fluxes and obliterates SAT2-dependent glutamine transport. Four additional disease-causing variants (R94W, R184C, N273I, Y276C) also impair these functions.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes; electrophysiology; glutamine transport assays; structure modeling\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution in Xenopus oocytes with multiple patient variants tested, two orthogonal functional readouts (K+ flux and glutamine transport)\",\n      \"pmids\": [\"27742667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Patient-derived fibroblasts with KCTD7 mutations and yeast lacking Whi2 (a KCTD7 sequence-similar protein) show impaired autophagy, establishing a conserved autophagy-lysosome defect as a disease mechanism in KCTD7 deficiency.\",\n      \"method\": \"Cell-based functional assays of patient fibroblasts; knockout yeast; electron microscopy\",\n      \"journal\": \"Annals of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — patient fibroblasts plus yeast model, two orthogonal model systems, single lab\",\n      \"pmids\": [\"30295347\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The CRL3-KCTD7 E3 ubiquitin ligase complex (comprising CUL3, KCTD7, and Rbx1) targets CLN5 for ubiquitination and proteasomal degradation; patient KCTD7 mutations disrupt KCTD7-CUL3 or KCTD7-CLN5 interactions, causing CLN5 accumulation in the ER, which impairs CLN6/8-mediated ER-to-Golgi trafficking of lysosomal enzymes.\",\n      \"method\": \"Co-immunoprecipitation; ubiquitination assays; KCTD7-deficient cell lines; ER trafficking assays; protein interaction studies with patient-derived variants\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal biochemical assays including ubiquitination, Co-IP, and trafficking studies; identifies substrate and downstream pathway mechanism\",\n      \"pmids\": [\"35921411\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"KCTD7 works in complex with Cullin-3 and Rbx1 to execute non-degradative ubiquitination of calpain 1 (at K398) and calpain 2 (at K280 and K674); KCTD7 mediates K6-, K27-, K29-, and K63-linked ubiquitin chains on calpain 1 and K6-linked chains on calpain 2. Loss of this ubiquitination leads to calpain hyperactivation, aberrant substrate cleavage, and caspase-3 activation. CRISPR/Cas9 Kctd7 knockout mice recapitulate human disease and calpain inhibition largely prevents neurodegeneration.\",\n      \"method\": \"In vitro ubiquitination assays; single-lysine ubiquitin mutants; co-immunoprecipitation; CRISPR/Cas9 mouse knockout; pharmacological calpain inhibition; behavioral and neuropathological analysis\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted ubiquitination with site-specific mutants, in vivo knockout rescue by pharmacological inhibition, multiple orthogonal methods\",\n      \"pmids\": [\"36964131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Kctd7 is expressed in inner retina neurons (not vessels) and its deletion in mice induces defective retinal vascular patterning (increased branching, vessel length, lacunarity) and delays emergence of superficial and deep vascular layers, accompanied by increased bipolar cell number and retinal function deficits, demonstrating neuronal Kctd7 drives neurovascular patterning.\",\n      \"method\": \"Kctd7 conditional mouse knockout; retinal immunohistochemistry; retinal vessel imaging; ERG functional assessment\",\n      \"journal\": \"Neurochemistry international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean knockout with specific cellular and vascular phenotypic readouts, single lab\",\n      \"pmids\": [\"31175897\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Kctd7-deficient mice develop myoclonic seizures, locomotor defects, Purkinje cell degeneration in the cerebellum, and cerebellar microvascular disorganization, establishing Kctd7 as required for Purkinje cell survival and modulator of neuron excitability linked to microvascular integrity.\",\n      \"method\": \"Kctd7 knockout mouse; EEG seizure monitoring; histological analysis; immunofluorescence; behavioral testing\",\n      \"journal\": \"Disease models & mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO mouse with defined cellular (Purkinje cell death) and circuit (seizure) phenotypes, single lab\",\n      \"pmids\": [\"35972048\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Whole-cell patch-clamp analysis of neuroblastoma cells overexpressing patient KCTD7 variant alleles demonstrated aberrant potassium regulation, and kctd7 knockout zebrafish showed global dysregulation of gene expression and increased c-fos transcription (a seizure activity marker).\",\n      \"method\": \"Patch-clamp electrophysiology; zinc finger nuclease zebrafish knockout; RNA-seq\",\n      \"journal\": \"Journal of neurogenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — electrophysiology with patient variants plus zebrafish KO model, two orthogonal systems\",\n      \"pmids\": [\"33970744\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KCTD7 functions as a substrate-binding adaptor for the CUL3-RBX1 E3 ubiquitin ligase complex, mediating non-degradative ubiquitination of calpains (suppressing their hyperactivation) and degradative ubiquitination of CLN5 (maintaining lysosomal enzyme trafficking from ER to Golgi); it also regulates neuronal potassium conductance and membrane hyperpolarization and modulates glutamine transporter SAT2 activity, with loss of any of these functions resulting in progressive myoclonic epilepsy and neurodegeneration.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"KCTD7 is a neuronal potassium conductance regulator and CUL3-RBX1 E3 ubiquitin ligase adaptor whose loss causes progressive myoclonic epilepsy and neuronal ceroid lipofuscinosis. It hyperpolarizes neuronal membranes in a K⁺-dependent manner and modulates the glutamine transporter SAT2 (SLC38A2), with disease-causing mutations impairing both K⁺ flux and SAT2-mediated glutamine transport [PMID:21710140, PMID:27742667]. As a substrate adaptor within the CRL3-KCTD7 complex, it directs non-degradative (K6/K27/K29/K63-linked) ubiquitination of calpains 1 and 2 to suppress their hyperactivation, and degradative ubiquitination of CLN5 to maintain CLN6/8-dependent ER-to-Golgi trafficking of lysosomal enzymes [PMID:35921411, PMID:36964131]. Kctd7 knockout mice develop myoclonic seizures, Purkinje cell degeneration, retinal neurovascular patterning defects, and calpain-driven neurodegeneration that is largely rescued by calpain inhibition [PMID:36964131, PMID:35972048, PMID:31175897].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing that KCTD7 regulates neuronal excitability answered the question of how loss-of-function mutations cause epilepsy: KCTD7 expression hyperpolarizes neurons via potassium conductance and physically interacts with Cullin-3.\",\n      \"evidence\": \"Patch-clamp electrophysiology in transfected neurons; co-immunoprecipitation\",\n      \"pmids\": [\"21710140\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the potassium channel(s) directly modulated by KCTD7 remains unknown\",\n        \"Mechanism linking CUL3 interaction to potassium conductance was not established\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrating that the patient R184C mutation abrogates CUL3 binding while KCTD7 localizes to the cytosol of neurons established that disrupted CUL3 interaction is a direct disease mechanism.\",\n      \"evidence\": \"Co-immunoprecipitation with patient mutant; immunofluorescence in cells and mouse brain\",\n      \"pmids\": [\"22748208\", \"22693283\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"How loss of CUL3 binding mechanistically leads to neurodegeneration was not resolved\",\n        \"Different subcellular localization findings between two labs not fully reconciled\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Reconstitution in Xenopus oocytes revealed that KCTD7 drives K⁺-dependent hyperpolarization and regulates the glutamine transporter SAT2, broadening the functional scope beyond ion channels to amino acid transport — with multiple patient variants ablating both functions.\",\n      \"evidence\": \"Heterologous expression in Xenopus oocytes; electrophysiology; glutamine transport assays with five patient variants\",\n      \"pmids\": [\"27742667\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether SAT2 regulation is direct or secondary to membrane potential changes was not resolved\",\n        \"Relevance of glutamine transport deficiency to neurodegeneration in vivo was not tested\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Patient fibroblasts and yeast lacking KCTD7-homolog Whi2 revealed impaired autophagy, establishing a conserved autophagy-lysosome axis as a disease mechanism.\",\n      \"evidence\": \"Cell-based autophagy assays in patient fibroblasts; yeast Whi2 knockout; electron microscopy\",\n      \"pmids\": [\"30295347\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular target through which KCTD7 controls autophagy was not identified\",\n        \"Yeast Whi2 functional equivalence to human KCTD7 not rigorously demonstrated\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Kctd7 knockout mice revealed that neuronal KCTD7 non-cell-autonomously drives retinal vascular patterning and deep layer formation, extending its roles beyond excitability to neurovascular development.\",\n      \"evidence\": \"Conditional Kctd7 mouse knockout; retinal immunohistochemistry; vessel imaging; ERG\",\n      \"pmids\": [\"31175897\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Signaling intermediates between neuronal KCTD7 and vascular patterning are unknown\",\n        \"Single lab finding; independent replication lacking\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Patient KCTD7 variants confirmed to impair potassium regulation by patch clamp, and kctd7 knockout zebrafish showed global transcriptional dysregulation and elevated seizure marker c-fos, validating the excitability phenotype across species.\",\n      \"evidence\": \"Patch-clamp in neuroblastoma cells; zinc-finger nuclease zebrafish knockout; RNA-seq\",\n      \"pmids\": [\"33970744\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct target genes versus secondary transcriptional changes not distinguished\",\n        \"Zebrafish phenotype not deeply characterized at the cellular or circuit level\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Two key advances resolved KCTD7's dual ubiquitin ligase substrates and in vivo neurodegeneration: CRL3-KCTD7 ubiquitinates CLN5 for proteasomal degradation to maintain ER-to-Golgi lysosomal enzyme trafficking, and Kctd7 KO mice develop myoclonic seizures and Purkinje cell degeneration.\",\n      \"evidence\": \"Ubiquitination assays and ER trafficking studies in KCTD7-deficient cells; Kctd7 KO mouse with EEG and histology\",\n      \"pmids\": [\"35921411\", \"35972048\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether CLN5 accumulation alone is sufficient to cause neurodegeneration was not tested\",\n        \"Relationship between Purkinje cell death and cerebellar microvascular disorganization is correlative\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identification of calpains 1 and 2 as non-degradative ubiquitination substrates of CRL3-KCTD7, with specific lysine sites and chain types mapped, established that calpain hyperactivation is a central neurodegenerative mechanism — validated by pharmacological rescue in KO mice.\",\n      \"evidence\": \"In vitro ubiquitination with single-lysine ubiquitin mutants; CRISPR Kctd7 KO mouse; calpain inhibitor rescue; behavioral and neuropathological analysis\",\n      \"pmids\": [\"36964131\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Relative contributions of calpain hyperactivation versus CLN5 accumulation to disease remain unclear\",\n        \"Whether non-degradative ubiquitination of calpains suppresses activity directly or via altered localization is not determined\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The identity of the potassium channel(s) directly modulated by KCTD7, the mechanistic link between K⁺ conductance and CUL3-mediated ubiquitination, and the relative pathogenic contribution of each substrate arm (calpain versus CLN5 versus SAT2) remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No potassium channel subunit has been identified as a direct KCTD7 binding partner\",\n        \"Whether CUL3-dependent and K⁺-conductance functions are mechanistically coupled or independent is unknown\",\n        \"Therapeutic relevance of calpain inhibition in human patients not established\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [6, 7]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2, 6, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0016567\", \"supporting_discovery_ids\": []},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [6, 7]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 4, 9]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\n      \"CRL3-KCTD7 (CUL3-KCTD7-RBX1)\"\n    ],\n    \"partners\": [\n      \"CUL3\",\n      \"RBX1\",\n      \"CLN5\",\n      \"CAPN1\",\n      \"CAPN2\",\n      \"SLC38A2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}