{"gene":"WASHC5","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2006,"finding":"Mutations in KIAA0196 (strumpellin) at residues L619 and V626 impair the normal function of the protein in vivo; rescue studies in zebrafish morphants showed that human mRNA carrying these mutations failed to restore normal function, establishing a functional role for these conserved residues.","method":"Zebrafish morpholino knockdown with mRNA rescue (in vivo functional assay)","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo rescue assay in zebrafish with specific mutants, single lab, direct functional readout","pmids":["17160902"],"is_preprint":false},{"year":2013,"finding":"A splice-site mutation in KIAA0196 causes approximately 60% reduction in strumpellin protein level (confirmed by western blot) and an ~8-fold reduction in a transcript lacking exon 27, causing Ritscher-Schinzel syndrome via loss of strumpellin protein.","method":"RNA analysis and western blot quantification of patient samples","journal":"Journal of medical genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct protein and RNA quantification from patient tissue, single lab, two orthogonal methods (RNA + protein)","pmids":["24065355"],"is_preprint":false},{"year":2015,"finding":"Homozygous knockout of the murine KIAA0196 homologue (E430025E21Rik) causes early embryonic lethality, while heterozygous mice show reduced WASH regulatory complex (SHRC) abundance at protein level without HSP-related phenotypes; heterozygous loss alone does not cause haploinsufficiency in mice, arguing against simple loss-of-function as the pathogenic mechanism.","method":"Murine knockout (deletion allele), qPCR, western blotting, motor performance assay, primary neuron/fibroblast cultures","journal":"Orphanet journal of rare diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cellular and in vivo phenotypes, multiple orthogonal methods (protein, RNA, behavior), single lab","pmids":["26572744"],"is_preprint":false},{"year":2020,"finding":"Strumpellin (WASHC5) is a core component of the WASH complex that activates actin nucleation at endosomes; SPG8-associated missense mutations in strumpellin cause endosomal fission defects and reduce CAV1 protein abundance by failing to inhibit lysosomal degradation of CAV1. Strumpellin interacts with CAV1 (caveolin-1) in cells, and this interaction stimulates integrin recycling and promotes cell adhesion; the WASH complex maintains CAV1 and integrin protein amounts by inhibiting their lysosomal degradation via endosomal actin nucleation activity.","method":"Immunoprecipitation and mass spectrometry (interactome), RNA interference (strumpellin knockdown), overexpression of wild-type and mutant strumpellin, cell-spreading assays, endosomal tubulation assays, western blotting","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with MS validation, RNAi loss-of-function with defined cellular phenotypes, rescue with WT vs. disease mutants, multiple orthogonal methods in a single rigorous study","pmids":["31911435"],"is_preprint":false},{"year":2023,"finding":"Strumpellin/WASHC5 regulates dendritic arborization and synapse formation in cortical neurons via actin polymerization; strumpellin knockdown reduced F-actin clusters in neuronal dendrites and impaired dendritic branching, which was rescued by wild-type strumpellin but not by SPG8 patient mutants N471D or V626F.","method":"Lentiviral shRNA knockdown in cortical motor neurons (in vivo and in vitro), rescue with wild-type and mutant strumpellin, quantification of dendritic morphology and F-actin clusters","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined neuronal phenotype and rescue, single lab, in vivo and in vitro","pmids":["37392480"],"is_preprint":false},{"year":2026,"finding":"WNT2B binds directly to the spectrin repeat domain (SRD) of WASHC5/strumpellin via its conserved middle domain, competitively displacing WASHC1 from the WASH complex, thereby disrupting WASH complex assembly and inhibiting WASHC1-mediated actin polymerization on early endosomes; this disruption impairs endosomal trafficking of ATG9A and inhibits autophagy initiation.","method":"Co-immunoprecipitation, GST pulldown, proximity ligation assay (PLA), super-resolution structured illumination microscopy (SIM), FRAP, WASH complex reconstitution assays, domain-mapping mutagenesis, mouse model (TNBS-induced colitis with fibroblast-specific wnt2b deletion)","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct binding mapped to specific domains by pulldown + Co-IP + PLA, functional consequence (actin polymerization, endosomal trafficking, autophagy) confirmed by multiple orthogonal methods and in vivo validation","pmids":["42233622"],"is_preprint":false},{"year":2023,"finding":"A splice-altering variant (c.712-2A>G) in WASHC5 alters mRNA splicing and changes the expression of genes in the WASH complex and endosomal/lysosomal pathways, establishing that WASHC5 splice mutations disrupt the WASH complex-endosomal pathway axis.","method":"RNA splicing analysis, Sanger sequencing, real-time qPCR of WASH complex and endosomal/lysosomal pathway genes","journal":"Frontiers in genetics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single case report, RNA-level analysis without functional rescue or protein-level mechanistic characterization","pmids":["38028608"],"is_preprint":false},{"year":2020,"finding":"KIAA0196 deficiency in zebrafish and mice (CRISPR/Cas9 knockout) causes sarcomere structural disorganization, myofibril integrity loss, and downregulation of sarcomeric genes (particularly MYH and MYL family), indicating KIAA0196 is required for myofibril structural integrity during cardiac development.","method":"CRISPR/Cas9 knockout in zebrafish and mice, immunostaining, electron microscopy, transcriptome and proteomics analyses","journal":"International journal of cardiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined cellular phenotype (sarcomere disorganization), multiple orthogonal methods (EM, immunostaining, transcriptomics, proteomics), single lab","pmids":["32417190"],"is_preprint":false}],"current_model":"WASHC5/strumpellin is a core subunit of the WASH complex that activates Arp2/3-mediated actin polymerization on early endosomes to drive endosomal tubulation and fission; it interacts with CAV1 to prevent lysosomal degradation of CAV1 and integrins (thereby promoting integrin recycling and cell adhesion), and its spectrin repeat domain is directly bound by WNT2B, which competitively displaces WASHC1, disrupts WASH complex assembly, impairs ATG9A trafficking, and inhibits autophagy; SPG8-causing missense mutations fail to rescue endosomal tubulation, CAV1 abundance, integrin-mediated adhesion, or neuronal dendritic actin organization, while complete loss of the protein is embryonic lethal, suggesting a toxic gain-of-function rather than simple haploinsufficiency as the likely pathomechanism in hereditary spastic paraplegia."},"narrative":{"mechanistic_narrative":"WASHC5 (strumpellin) is a core subunit of the WASH complex that drives Arp2/3-mediated actin nucleation on early endosomes to control endosomal tubulation and fission, a function essential for endosomal trafficking and protein homeostasis [PMID:31911435]. Through this endosomal actin activity, WASHC5 interacts with CAV1 and inhibits lysosomal degradation of CAV1 and integrins, thereby promoting integrin recycling and cell adhesion [PMID:31911435]. WASH complex integrity is regulated by competitive partner exchange: WNT2B binds directly to the spectrin repeat domain of WASHC5 and displaces WASHC1, disrupting complex assembly, abolishing WASHC1-mediated actin polymerization, impairing ATG9A trafficking, and inhibiting autophagy initiation [PMID:42233622]. WASHC5-dependent actin organization also shapes neuronal architecture, supporting dendritic F-actin clustering, dendritic branching, and synapse formation in cortical neurons [PMID:37392480], and is required for myofibril structural integrity during cardiac development [PMID:32417190]. SPG8-associated missense mutations fail to rescue endosomal tubulation, CAV1 abundance, integrin-mediated adhesion, or dendritic actin organization [PMID:31911435, PMID:37392480], while complete loss of the murine homologue is embryonic lethal and heterozygous loss does not produce disease phenotypes, indicating that simple haploinsufficiency is not the pathogenic mechanism [PMID:26572744]. Splice-altering and loss-of-function variants in WASHC5 cause Ritscher-Schinzel syndrome and disrupt the WASH complex-endosomal pathway axis [PMID:24065355, PMID:38028608].","teleology":[{"year":2006,"claim":"Established that specific conserved residues of strumpellin are functionally required in vivo, providing the first evidence that disease-associated substitutions impair protein function rather than being benign.","evidence":"Zebrafish morpholino knockdown with human wild-type vs. mutant mRNA rescue","pmids":["17160902"],"confidence":"Medium","gaps":["No molecular mechanism for how the residues contribute to function","No protein partners or biochemical activity identified"]},{"year":2013,"claim":"Showed that a splice-site mutation reduces strumpellin protein levels and causes Ritscher-Schinzel syndrome, linking loss of protein to human disease.","evidence":"RNA analysis and western blot quantification of patient samples","pmids":["24065355"],"confidence":"Medium","gaps":["Single case-level evidence","Does not define the cellular mechanism downstream of reduced protein"]},{"year":2015,"claim":"Distinguished the pathogenic mechanism by showing complete knockout is embryonic lethal while heterozygous loss spares HSP phenotypes, arguing against simple haploinsufficiency.","evidence":"Murine deletion allele knockout with qPCR, western blot, motor and primary culture assays","pmids":["26572744"],"confidence":"Medium","gaps":["Does not establish whether SPG8 mutations act by gain-of-function","Mechanism of embryonic lethality not defined"]},{"year":2020,"claim":"Defined the core molecular function of strumpellin as a WASH complex subunit driving endosomal actin nucleation, and linked it to CAV1/integrin homeostasis, adhesion, and SPG8 mutant defects.","evidence":"IP-MS interactome, RNAi knockdown, WT/mutant rescue, cell-spreading and endosomal tubulation assays","pmids":["31911435"],"confidence":"High","gaps":["Direct structural basis of the CAV1 interaction not resolved","How endosomal defects translate to neuronal pathology not addressed"]},{"year":2020,"claim":"Extended strumpellin function beyond endosomes to myofibril assembly, showing it is required for sarcomere structural integrity during cardiac development.","evidence":"CRISPR/Cas9 knockout in zebrafish and mice with EM, immunostaining, transcriptomics, proteomics","pmids":["32417190"],"confidence":"Medium","gaps":["Mechanistic link between WASH/actin activity and sarcomeric gene downregulation unclear","Direct sarcomeric partners not identified"]},{"year":2023,"claim":"Demonstrated that strumpellin shapes neuronal morphology via actin, with SPG8 mutants failing to rescue dendritic branching and F-actin clusters, connecting its actin function to disease-relevant neuronal defects.","evidence":"Lentiviral shRNA knockdown in cortical neurons with WT/mutant rescue and morphology quantification","pmids":["37392480"],"confidence":"Medium","gaps":["Does not establish whether dendritic phenotype is endosome-dependent","No direct measurement of Arp2/3 activity in neurons"]},{"year":2023,"claim":"Provided patient-level evidence that a splice-altering WASHC5 variant perturbs WASH complex and endosomal/lysosomal pathway gene expression.","evidence":"RNA splicing analysis, Sanger sequencing, qPCR of pathway genes (single case report)","pmids":["38028608"],"confidence":"Low","gaps":["Single case report without functional rescue","No protein-level or mechanistic validation"]},{"year":2026,"claim":"Revealed a regulatory mechanism in which WNT2B competitively displaces WASHC1 from the WASHC5 spectrin repeat domain to disrupt WASH complex assembly, impair ATG9A trafficking, and inhibit autophagy.","evidence":"Co-IP, GST pulldown, PLA, super-resolution SIM, FRAP, complex reconstitution, domain mutagenesis, colitis mouse model","pmids":["42233622"],"confidence":"High","gaps":["Structural model of the SRD-WNT2B interface not resolved","Relevance to SPG8/HSP pathology not directly tested"]},{"year":null,"claim":"Whether SPG8 missense mutations act through a defined toxic gain-of-function and how the diverse endosomal, neuronal, and myofibrillar roles of WASHC5 are mechanistically unified remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of strumpellin within the assembled WASH complex","Mechanistic basis distinguishing gain-of-function from loss-of-function in disease unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[3,4,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[3,5]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[3,5]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[4,7]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,6]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5]}],"complexes":["WASH complex"],"partners":["WASHC1","CAV1","WNT2B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q12768","full_name":"WASH complex subunit 5","aliases":["Strumpellin","WASH complex subunit strumpellin"],"length_aa":1159,"mass_kda":134.3,"function":"Acts as a component of the WASH core complex that functions as a nucleation-promoting factor (NPF) at the surface of endosomes, where it recruits and activates the Arp2/3 complex to induce actin polymerization, playing a key role in the fission of tubules that serve as transport intermediates during endosome sorting (PubMed:19922875, PubMed:20498093). May be involved in axonal outgrowth. Involved in cellular localization of ADRB2 (PubMed:23085491). Involved in cellular trafficking of BLOC-1 complex cargos such as ATP7A and VAMP7 (PubMed:23676666)","subcellular_location":"Cytoplasm, cytosol; Endoplasmic reticulum; Early endosome","url":"https://www.uniprot.org/uniprotkb/Q12768/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/WASHC5","classification":"Not Classified","n_dependent_lines":149,"n_total_lines":1208,"dependency_fraction":0.12334437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CAPZB","stoichiometry":4.0},{"gene":"VPS35","stoichiometry":4.0}],"url":"https://opencell.sf.czbiohub.org/search/WASHC5","total_profiled":1310},"omim":[{"mim_id":"619925","title":"WASH COMPLEX, SUBUNIT 3; WASHC3","url":"https://www.omim.org/entry/619925"},{"mim_id":"619135","title":"RITSCHER-SCHINZEL SYNDROME 3; RTSC3","url":"https://www.omim.org/entry/619135"},{"mim_id":"618981","title":"VPS35 ENDOSOMAL PROTEIN-SORTING FACTOR-LIKE; VPS35L","url":"https://www.omim.org/entry/618981"},{"mim_id":"615748","title":"WASH COMPLEX, SUBUNIT 4; WASHC4","url":"https://www.omim.org/entry/615748"},{"mim_id":"613632","title":"WASH COMPLEX, SUBUNIT 1; WASHC1","url":"https://www.omim.org/entry/613632"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Cytokinetic bridge","reliability":"Additional"},{"location":"Mitotic spindle","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Centrosome","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/WASHC5"},"hgnc":{"alias_symbol":[],"prev_symbol":["SPG8","KIAA0196"]},"alphafold":{"accession":"Q12768","domains":[{"cath_id":"-","chopping":"9-192","consensus_level":"high","plddt":90.1397,"start":9,"end":192},{"cath_id":"1.20.1440","chopping":"432-544","consensus_level":"medium","plddt":84.0496,"start":432,"end":544},{"cath_id":"-","chopping":"865-1157","consensus_level":"medium","plddt":89.7877,"start":865,"end":1157}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q12768","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q12768-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q12768-F1-predicted_aligned_error_v6.png","plddt_mean":90.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=WASHC5","jax_strain_url":"https://www.jax.org/strain/search?query=WASHC5"},"sequence":{"accession":"Q12768","fasta_url":"https://rest.uniprot.org/uniprotkb/Q12768.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q12768/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q12768"}},"corpus_meta":[{"pmid":"17160902","id":"PMC_17160902","title":"Mutations in the KIAA0196 gene at the SPG8 locus cause hereditary spastic paraplegia.","date":"2006","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/17160902","citation_count":157,"is_preprint":false},{"pmid":"24065355","id":"PMC_24065355","title":"A novel mutation in KIAA0196: identification of a gene involved in Ritscher-Schinzel/3C syndrome in a First Nations cohort.","date":"2013","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24065355","citation_count":62,"is_preprint":false},{"pmid":"14603436","id":"PMC_14603436","title":"RAD21 and KIAA0196 at 8q24 are amplified and overexpressed in prostate cancer.","date":"2004","source":"Genes, chromosomes & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/14603436","citation_count":60,"is_preprint":false},{"pmid":"23455931","id":"PMC_23455931","title":"Pure adult-onset spastic paraplegia caused by a novel mutation in the KIAA0196 (SPG8) gene.","date":"2013","source":"Journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/23455931","citation_count":31,"is_preprint":false},{"pmid":"10563637","id":"PMC_10563637","title":"Autosomal dominant spastic paraplegia: refined SPG8 locus and additional genetic heterogeneity.","date":"1999","source":"Neurology","url":"https://pubmed.ncbi.nlm.nih.gov/10563637","citation_count":26,"is_preprint":false},{"pmid":"31911435","id":"PMC_31911435","title":"Hereditary spastic paraplegia SPG8 mutations impair CAV1-dependent, integrin-mediated cell adhesion.","date":"2020","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/31911435","citation_count":21,"is_preprint":false},{"pmid":"26572744","id":"PMC_26572744","title":"The spectrum of KIAA0196 variants, and characterization of a murine knockout: implications for the mutational mechanism in hereditary spastic paraplegia type SPG8.","date":"2015","source":"Orphanet journal of rare diseases","url":"https://pubmed.ncbi.nlm.nih.gov/26572744","citation_count":16,"is_preprint":false},{"pmid":"25454649","id":"PMC_25454649","title":"A novel strumpellin mutation and potential pitfalls in the molecular diagnosis of hereditary spastic paraplegia type SPG8.","date":"2014","source":"Journal of the neurological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/25454649","citation_count":16,"is_preprint":false},{"pmid":"31814071","id":"PMC_31814071","title":"SPG8 mutations in Italian families: clinical data and literature review.","date":"2019","source":"Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/31814071","citation_count":9,"is_preprint":false},{"pmid":"36130690","id":"PMC_36130690","title":"Expanding the pre- and postnatal phenotype of WASHC5 and CCDC22 -related Ritscher-Schinzel syndromes.","date":"2022","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36130690","citation_count":9,"is_preprint":false},{"pmid":"26967522","id":"PMC_26967522","title":"Exome sequencing reveals a novel missense mutation in the KIAA0196 gene in a Japanese patient with SPG8.","date":"2016","source":"Clinical neurology and neurosurgery","url":"https://pubmed.ncbi.nlm.nih.gov/26967522","citation_count":9,"is_preprint":false},{"pmid":"29768361","id":"PMC_29768361","title":"A novel KIAA0196 mutation in a Chinese patient with spastic paraplegia 8: A case report.","date":"2018","source":"Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/29768361","citation_count":6,"is_preprint":false},{"pmid":"38028608","id":"PMC_38028608","title":"Case report: A novel WASHC5 variant altering mRNA splicing causes spastic paraplegia in a patient.","date":"2023","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38028608","citation_count":2,"is_preprint":false},{"pmid":"37392480","id":"PMC_37392480","title":"Strumpellin/WASHC5 regulates the structural plasticity of cortical neurons involved in gait coordination.","date":"2023","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/37392480","citation_count":1,"is_preprint":false},{"pmid":"32417190","id":"PMC_32417190","title":"Identification of KIAA0196 as a novel susceptibility gene for myofibril structural disorganization in cardiac development.","date":"2020","source":"International journal of cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/32417190","citation_count":1,"is_preprint":false},{"pmid":"39988189","id":"PMC_39988189","title":"Disrupted maxillofacial, cardiovascular, and nervous development in washc5 knockout Zebrafish: Insights into 3C syndrome.","date":"2025","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/39988189","citation_count":0,"is_preprint":false},{"pmid":"31055811","id":"PMC_31055811","title":"[Analysis of KIAA0196 gene mutation in a family with hereditary spastic paraplegia].","date":"2019","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31055811","citation_count":0,"is_preprint":false},{"pmid":"31645484","id":"PMC_31645484","title":"[Establishment and preliminary mechanism study of the zebrafish strain of KIAA0196: A candidate pathogenic gene for heart development].","date":"2019","source":"Zhong nan da xue xue bao. Yi xue ban = Journal of Central South University. Medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31645484","citation_count":0,"is_preprint":false},{"pmid":"42233622","id":"PMC_42233622","title":"WNT2B impairs endosomal trafficking via WASHC5 to inhibit autophagy: a novel non-secretory WNT pathway.","date":"2026","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/42233622","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.27.630484","title":"Phenolic compounds in  <i>Medicago truncatula</i>  roots are under the influence of  <i>Agrobacterium fabrum</i>  through its species specific-genes regions","date":"2024-12-27","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.27.630484","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12369,"output_tokens":2252,"usd":0.035444,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9310,"output_tokens":2789,"usd":0.058138,"stage2_stop_reason":"end_turn"},"total_usd":0.093582,"stage1_batch_id":"msgbatch_01UT1AahFPCAyn2uVweS7A9z","stage2_batch_id":"msgbatch_01HuKWtKNT4Pqj1bc8eEP5RV","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"Mutations in KIAA0196 (strumpellin) at residues L619 and V626 impair the normal function of the protein in vivo; rescue studies in zebrafish morphants showed that human mRNA carrying these mutations failed to restore normal function, establishing a functional role for these conserved residues.\",\n      \"method\": \"Zebrafish morpholino knockdown with mRNA rescue (in vivo functional assay)\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo rescue assay in zebrafish with specific mutants, single lab, direct functional readout\",\n      \"pmids\": [\"17160902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A splice-site mutation in KIAA0196 causes approximately 60% reduction in strumpellin protein level (confirmed by western blot) and an ~8-fold reduction in a transcript lacking exon 27, causing Ritscher-Schinzel syndrome via loss of strumpellin protein.\",\n      \"method\": \"RNA analysis and western blot quantification of patient samples\",\n      \"journal\": \"Journal of medical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct protein and RNA quantification from patient tissue, single lab, two orthogonal methods (RNA + protein)\",\n      \"pmids\": [\"24065355\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Homozygous knockout of the murine KIAA0196 homologue (E430025E21Rik) causes early embryonic lethality, while heterozygous mice show reduced WASH regulatory complex (SHRC) abundance at protein level without HSP-related phenotypes; heterozygous loss alone does not cause haploinsufficiency in mice, arguing against simple loss-of-function as the pathogenic mechanism.\",\n      \"method\": \"Murine knockout (deletion allele), qPCR, western blotting, motor performance assay, primary neuron/fibroblast cultures\",\n      \"journal\": \"Orphanet journal of rare diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cellular and in vivo phenotypes, multiple orthogonal methods (protein, RNA, behavior), single lab\",\n      \"pmids\": [\"26572744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Strumpellin (WASHC5) is a core component of the WASH complex that activates actin nucleation at endosomes; SPG8-associated missense mutations in strumpellin cause endosomal fission defects and reduce CAV1 protein abundance by failing to inhibit lysosomal degradation of CAV1. Strumpellin interacts with CAV1 (caveolin-1) in cells, and this interaction stimulates integrin recycling and promotes cell adhesion; the WASH complex maintains CAV1 and integrin protein amounts by inhibiting their lysosomal degradation via endosomal actin nucleation activity.\",\n      \"method\": \"Immunoprecipitation and mass spectrometry (interactome), RNA interference (strumpellin knockdown), overexpression of wild-type and mutant strumpellin, cell-spreading assays, endosomal tubulation assays, western blotting\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with MS validation, RNAi loss-of-function with defined cellular phenotypes, rescue with WT vs. disease mutants, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"31911435\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Strumpellin/WASHC5 regulates dendritic arborization and synapse formation in cortical neurons via actin polymerization; strumpellin knockdown reduced F-actin clusters in neuronal dendrites and impaired dendritic branching, which was rescued by wild-type strumpellin but not by SPG8 patient mutants N471D or V626F.\",\n      \"method\": \"Lentiviral shRNA knockdown in cortical motor neurons (in vivo and in vitro), rescue with wild-type and mutant strumpellin, quantification of dendritic morphology and F-actin clusters\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined neuronal phenotype and rescue, single lab, in vivo and in vitro\",\n      \"pmids\": [\"37392480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"WNT2B binds directly to the spectrin repeat domain (SRD) of WASHC5/strumpellin via its conserved middle domain, competitively displacing WASHC1 from the WASH complex, thereby disrupting WASH complex assembly and inhibiting WASHC1-mediated actin polymerization on early endosomes; this disruption impairs endosomal trafficking of ATG9A and inhibits autophagy initiation.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, proximity ligation assay (PLA), super-resolution structured illumination microscopy (SIM), FRAP, WASH complex reconstitution assays, domain-mapping mutagenesis, mouse model (TNBS-induced colitis with fibroblast-specific wnt2b deletion)\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct binding mapped to specific domains by pulldown + Co-IP + PLA, functional consequence (actin polymerization, endosomal trafficking, autophagy) confirmed by multiple orthogonal methods and in vivo validation\",\n      \"pmids\": [\"42233622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"A splice-altering variant (c.712-2A>G) in WASHC5 alters mRNA splicing and changes the expression of genes in the WASH complex and endosomal/lysosomal pathways, establishing that WASHC5 splice mutations disrupt the WASH complex-endosomal pathway axis.\",\n      \"method\": \"RNA splicing analysis, Sanger sequencing, real-time qPCR of WASH complex and endosomal/lysosomal pathway genes\",\n      \"journal\": \"Frontiers in genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single case report, RNA-level analysis without functional rescue or protein-level mechanistic characterization\",\n      \"pmids\": [\"38028608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"KIAA0196 deficiency in zebrafish and mice (CRISPR/Cas9 knockout) causes sarcomere structural disorganization, myofibril integrity loss, and downregulation of sarcomeric genes (particularly MYH and MYL family), indicating KIAA0196 is required for myofibril structural integrity during cardiac development.\",\n      \"method\": \"CRISPR/Cas9 knockout in zebrafish and mice, immunostaining, electron microscopy, transcriptome and proteomics analyses\",\n      \"journal\": \"International journal of cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined cellular phenotype (sarcomere disorganization), multiple orthogonal methods (EM, immunostaining, transcriptomics, proteomics), single lab\",\n      \"pmids\": [\"32417190\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"WASHC5/strumpellin is a core subunit of the WASH complex that activates Arp2/3-mediated actin polymerization on early endosomes to drive endosomal tubulation and fission; it interacts with CAV1 to prevent lysosomal degradation of CAV1 and integrins (thereby promoting integrin recycling and cell adhesion), and its spectrin repeat domain is directly bound by WNT2B, which competitively displaces WASHC1, disrupts WASH complex assembly, impairs ATG9A trafficking, and inhibits autophagy; SPG8-causing missense mutations fail to rescue endosomal tubulation, CAV1 abundance, integrin-mediated adhesion, or neuronal dendritic actin organization, while complete loss of the protein is embryonic lethal, suggesting a toxic gain-of-function rather than simple haploinsufficiency as the likely pathomechanism in hereditary spastic paraplegia.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"WASHC5 (strumpellin) is a core subunit of the WASH complex that drives Arp2/3-mediated actin nucleation on early endosomes to control endosomal tubulation and fission, a function essential for endosomal trafficking and protein homeostasis [#3]. Through this endosomal actin activity, WASHC5 interacts with CAV1 and inhibits lysosomal degradation of CAV1 and integrins, thereby promoting integrin recycling and cell adhesion [#3]. WASH complex integrity is regulated by competitive partner exchange: WNT2B binds directly to the spectrin repeat domain of WASHC5 and displaces WASHC1, disrupting complex assembly, abolishing WASHC1-mediated actin polymerization, impairing ATG9A trafficking, and inhibiting autophagy initiation [#5]. WASHC5-dependent actin organization also shapes neuronal architecture, supporting dendritic F-actin clustering, dendritic branching, and synapse formation in cortical neurons [#4], and is required for myofibril structural integrity during cardiac development [#7]. SPG8-associated missense mutations fail to rescue endosomal tubulation, CAV1 abundance, integrin-mediated adhesion, or dendritic actin organization [#3, #4], while complete loss of the murine homologue is embryonic lethal and heterozygous loss does not produce disease phenotypes, indicating that simple haploinsufficiency is not the pathogenic mechanism [#2]. Splice-altering and loss-of-function variants in WASHC5 cause Ritscher-Schinzel syndrome and disrupt the WASH complex-endosomal pathway axis [#1, #6].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that specific conserved residues of strumpellin are functionally required in vivo, providing the first evidence that disease-associated substitutions impair protein function rather than being benign.\",\n      \"evidence\": \"Zebrafish morpholino knockdown with human wild-type vs. mutant mRNA rescue\",\n      \"pmids\": [\"17160902\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular mechanism for how the residues contribute to function\", \"No protein partners or biochemical activity identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed that a splice-site mutation reduces strumpellin protein levels and causes Ritscher-Schinzel syndrome, linking loss of protein to human disease.\",\n      \"evidence\": \"RNA analysis and western blot quantification of patient samples\",\n      \"pmids\": [\"24065355\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single case-level evidence\", \"Does not define the cellular mechanism downstream of reduced protein\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Distinguished the pathogenic mechanism by showing complete knockout is embryonic lethal while heterozygous loss spares HSP phenotypes, arguing against simple haploinsufficiency.\",\n      \"evidence\": \"Murine deletion allele knockout with qPCR, western blot, motor and primary culture assays\",\n      \"pmids\": [\"26572744\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not establish whether SPG8 mutations act by gain-of-function\", \"Mechanism of embryonic lethality not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined the core molecular function of strumpellin as a WASH complex subunit driving endosomal actin nucleation, and linked it to CAV1/integrin homeostasis, adhesion, and SPG8 mutant defects.\",\n      \"evidence\": \"IP-MS interactome, RNAi knockdown, WT/mutant rescue, cell-spreading and endosomal tubulation assays\",\n      \"pmids\": [\"31911435\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct structural basis of the CAV1 interaction not resolved\", \"How endosomal defects translate to neuronal pathology not addressed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended strumpellin function beyond endosomes to myofibril assembly, showing it is required for sarcomere structural integrity during cardiac development.\",\n      \"evidence\": \"CRISPR/Cas9 knockout in zebrafish and mice with EM, immunostaining, transcriptomics, proteomics\",\n      \"pmids\": [\"32417190\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between WASH/actin activity and sarcomeric gene downregulation unclear\", \"Direct sarcomeric partners not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrated that strumpellin shapes neuronal morphology via actin, with SPG8 mutants failing to rescue dendritic branching and F-actin clusters, connecting its actin function to disease-relevant neuronal defects.\",\n      \"evidence\": \"Lentiviral shRNA knockdown in cortical neurons with WT/mutant rescue and morphology quantification\",\n      \"pmids\": [\"37392480\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not establish whether dendritic phenotype is endosome-dependent\", \"No direct measurement of Arp2/3 activity in neurons\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Provided patient-level evidence that a splice-altering WASHC5 variant perturbs WASH complex and endosomal/lysosomal pathway gene expression.\",\n      \"evidence\": \"RNA splicing analysis, Sanger sequencing, qPCR of pathway genes (single case report)\",\n      \"pmids\": [\"38028608\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single case report without functional rescue\", \"No protein-level or mechanistic validation\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Revealed a regulatory mechanism in which WNT2B competitively displaces WASHC1 from the WASHC5 spectrin repeat domain to disrupt WASH complex assembly, impair ATG9A trafficking, and inhibit autophagy.\",\n      \"evidence\": \"Co-IP, GST pulldown, PLA, super-resolution SIM, FRAP, complex reconstitution, domain mutagenesis, colitis mouse model\",\n      \"pmids\": [\"42233622\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural model of the SRD-WNT2B interface not resolved\", \"Relevance to SPG8/HSP pathology not directly tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether SPG8 missense mutations act through a defined toxic gain-of-function and how the diverse endosomal, neuronal, and myofibrillar roles of WASHC5 are mechanistically unified remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of strumpellin within the assembled WASH complex\", \"Mechanistic basis distinguishing gain-of-function from loss-of-function in disease unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [3, 4, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [3, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [3, 5]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [4, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 6]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\"WASH complex\"],\n    \"partners\": [\"WASHC1\", \"CAV1\", \"WNT2B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}