{"gene":"SESTD1","run_date":"2026-06-10T07:46:31","timeline":{"discoveries":[{"year":2010,"finding":"SESTD1 was identified as a novel binding partner of TRPC4 and TRPC5 channels, associating via the channel's calmodulin- and inositol 1,4,5-trisphosphate receptor-binding (CIRB) domain. SESTD1 contains a lipid-binding SEC14-like domain and spectrin-type cytoskeleton interaction domains, binds multiple phospholipid species in vitro in a Ca2+-dependent manner, and is essential for efficient receptor-mediated activation of TRPC5.","method":"Yeast two-hybrid screen of human aortic cDNA library, co-immunoprecipitation, in vitro phospholipid-binding assays, functional (electrophysiological) studies, domain-mapping experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods in one study: Y2H identification, reciprocal Co-IP, in vitro lipid-binding assay with Ca2+ dependence, and functional TRPC5 activation assay; foundational mechanistic paper for this gene","pmids":["20164195"],"is_preprint":false},{"year":2013,"finding":"Sestd1 is a novel binding partner of both Vangl2 and Dact1 in the Wnt/Planar Cell Polarity (PCP) pathway. The Sestd1–Dact1 interface maps to the C-terminal region of Sestd1 and the N-terminal region of Dact1. Genetic knockout of Sestd1 in mice phenocopies Dact1 knockout (neural tube defects, shortened/curly tail, developmental malformations), and Sestd1 KO shows reciprocal genetic rescue with a semidominant Vangl2 mutation, placing Sestd1 in the PCP pathway upstream of or parallel to Vangl2. In cell-based assays, the Sestd1–Dact1 interaction induces Rho GTPase activation.","method":"Co-immunoprecipitation, domain-mapping, mouse knockout generation, genetic epistasis (Vangl2 semidominant allele rescue), Wnt pathway activity assays, cell-based Rho GTPase activation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, in vivo KO phenotyping, genetic epistasis with Vangl2 allele, and cell-based functional assay; multiple orthogonal methods","pmids":["23696638"],"is_preprint":false},{"year":2013,"finding":"Dvl2 forms complexes with Sestd1 independently of both Dact1 and Vangl2. In cell-based assays, Sestd1 does not alter Dvl2 activation of Wnt/β-catenin signaling, but Dvl2 enhances activation of Rho family GTPases by the Dact1–Sestd1 complex. Genetic experiments show that Dvl2 KO, recessive in wild-type background, causes dominant embryonic lethality in Sestd1 or Dact1 KO backgrounds, indicating genetic synergy distinct from the epistasis between Sestd1 and Dact1.","method":"Co-immunoprecipitation, cell-based β-catenin and Rho GTPase reporter assays, mouse double-KO genetic interaction analysis","journal":"Communicative & integrative biology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP and cell-based assays combined with in vivo genetic synergy, single lab, complementary to PMID:23696638","pmids":["24505507"],"is_preprint":false},{"year":2015,"finding":"SESTD1 negatively regulates dendritic spine density in hippocampal neurons by interfering with the interaction between Rac1 and its guanine nucleotide exchange factor Trio8. The SPEC1 domain of SESTD1 mediates interaction with Rac1. Overexpression of SESTD1 decreases spine density and miniature excitatory postsynaptic current (mEPSC) frequency; knockdown of SESTD1 increases spine density and mEPSC frequency. Transfection of the GEF domain of Trio8 rescues the SESTD1-mediated decrease in spine density.","method":"Overexpression and siRNA knockdown in cultured hippocampal neurons, co-immunoprecipitation (Rac1–SESTD1 interaction), domain deletion/mutation mapping (SPEC1), electrophysiology (mEPSC recording), rescue experiments with Trio8-GEF domain","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods: Co-IP for interaction, gain-of-function/loss-of-function in neurons, electrophysiology, and domain-specific rescue; comprehensive single-lab study","pmids":["26272757"],"is_preprint":false},{"year":2015,"finding":"SESTD1 is required for efficient West Nile virus (Kunjin strain) replication in human cells. siRNA depletion of SESTD1 reduced WNVKUN replication. miR-532-5p targets and downregulates SESTD1 expression, and this suppression mediates an antiviral host response.","method":"siRNA knockdown of SESTD1 in human cells with viral replication assay, miRNA target validation (luciferase/reporter assays implied, qRT-PCR), in vivo mouse brain expression analysis","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — siRNA loss-of-function with viral replication readout, miRNA target validation, replicated in mouse brain; single lab","pmids":["26676784"],"is_preprint":false},{"year":2019,"finding":"Sestd1 is a synapse protein that shifts from the presynaptic to postsynaptic compartment as neurons mature postnatally in the mouse hippocampus. Conditional/global deletion of Sestd1 reduces dendrite arbors, spines, and excitatory synapses in hippocampal pyramidal neurons, with cell-autonomous reductions in both AMPA- and NMDA-mediated EPSCs. These deficits are associated with increased activation of Rac1 and RhoA. Co-immunoprecipitation and mass spectrometry identified BCR (Breakpoint Cluster Region), a Rho GTPase-activating protein (GAP), as a Sestd1 complex partner in brain tissue.","method":"Mouse genetic knockout, in vivo fractionation and immunofluorescence for synaptic localization, electrophysiology (AMPA- and NMDA-EPSC recording), co-immunoprecipitation from brain tissue coupled with mass spectrometry, Rho GTPase activation assays","journal":"Cerebral cortex","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO with defined cellular phenotype, electrophysiology, subcellular fractionation with functional consequence, and Co-IP/MS for interactor identification; multiple orthogonal methods","pmids":["29293918"],"is_preprint":false}],"current_model":"SESTD1 is a phospholipid-binding scaffold protein with a SEC14-like lipid-binding domain and spectrin-repeat cytoskeleton interaction domains that acts as a regulator of TRPC4/TRPC5 cation channels (via their CIRB domain), the Wnt/Planar Cell Polarity pathway (through complexes with Vangl2, Dact1, and Dvl2), and dendritic spine and excitatory synapse formation (by modulating Rho family GTPase activity via interactions with Rac1, BCR-GAP, and the GEF Trio8); its lipid binding is Ca2+-dependent, and loss of Sestd1 in mice leads to developmental defects, reduced dendrite arbors, fewer excitatory synapses, and decreased excitatory postsynaptic currents, while in human cells it is required for efficient West Nile virus replication."},"narrative":{"mechanistic_narrative":"SESTD1 is a Ca2+-dependent phospholipid-binding scaffold protein that couples membrane lipid signaling to cytoskeletal regulation and Rho-family GTPase control across ion channel, developmental, and synaptic contexts [PMID:20164195, PMID:23696638, PMID:29293918]. Through its SEC14-like lipid-binding domain and spectrin-type cytoskeleton interaction domains, it binds multiple phospholipid species in a Ca2+-dependent manner and associates with the CIRB domain of TRPC4 and TRPC5 channels, where it is required for efficient receptor-mediated TRPC5 activation [PMID:20164195]. In the Wnt/Planar Cell Polarity pathway, SESTD1 binds Vangl2 and Dact1 and, through the Dact1 interaction, activates Rho GTPases; mouse knockout phenocopies Dact1 loss with neural tube and tail defects and shows genetic interactions with Vangl2 and Dvl2, the latter potentiating Rho activation by the Dact1–Sestd1 complex [PMID:23696638, PMID:24505507]. In neurons, SESTD1 acts as a brake on excitatory connectivity: its SPEC1 domain binds Rac1 and interferes with the Rac1–Trio8 GEF interaction to limit dendritic spine density and mEPSC frequency [PMID:26272757], and loss of Sestd1 in mice reduces dendrite arbors, spines, and excitatory synapses with elevated Rac1 and RhoA activation, in part via complex formation with the Rho-GAP BCR [PMID:29293918]. SESTD1 is also required for efficient West Nile virus (Kunjin) replication in human cells and is targeted by the antiviral miRNA miR-532-5p [PMID:26676784].","teleology":[{"year":2010,"claim":"Established SESTD1 as a TRPC4/TRPC5 channel-associated, Ca2+-dependent lipid-binding protein, defining its core biochemical identity and a functional role in channel activation.","evidence":"Yeast two-hybrid screen, reciprocal Co-IP, in vitro phospholipid-binding assays, domain mapping, and electrophysiology in heterologous cells","pmids":["20164195"],"confidence":"High","gaps":["Lipid-binding specificity in vivo not resolved","No structural model of the SEC14-like or spectrin domains","Whether lipid binding gates TRPC5 regulation directly was not dissected"]},{"year":2013,"claim":"Placed Sestd1 in the Wnt/PCP pathway as a Vangl2- and Dact1-binding partner that activates Rho GTPases, connecting it to morphogenetic signaling.","evidence":"Reciprocal Co-IP, domain mapping, mouse knockout phenotyping, genetic epistasis with a Vangl2 semidominant allele, and cell-based Rho GTPase assays","pmids":["23696638"],"confidence":"High","gaps":["Molecular mechanism by which the Dact1–Sestd1 interface activates Rho not defined","Direct GEF/GAP not identified in this context","Whether lipid binding contributes to PCP function untested"]},{"year":2013,"claim":"Distinguished a Dvl2 branch from the Dact1 axis, showing Dvl2 potentiates Rho activation by the Dact1–Sestd1 complex without affecting β-catenin signaling, and revealing genetic synergy.","evidence":"Co-IP, cell-based β-catenin and Rho GTPase reporter assays, and mouse double-knockout genetic interaction analysis","pmids":["24505507"],"confidence":"Medium","gaps":["Single-lab study","Biochemical basis of Dvl2-enhanced Rho activation unresolved","Compartment where the complexes form not defined"]},{"year":2015,"claim":"Defined a synaptic mechanism in which SESTD1 limits spine density by disrupting the Rac1–Trio8 GEF interaction, identifying the SPEC1 domain as the Rac1-binding module.","evidence":"Overexpression and siRNA knockdown in hippocampal neurons, Co-IP, SPEC1 domain mapping, mEPSC recording, and Trio8-GEF rescue","pmids":["26272757"],"confidence":"High","gaps":["How SESTD1 physically blocks Rac1–Trio8 not structurally defined","Link to lipid-binding or channel functions untested","In vivo confirmation pending in this study"]},{"year":2015,"claim":"Identified SESTD1 as a host factor required for efficient West Nile virus replication and a target of antiviral miR-532-5p, extending its roles to virus–host interaction.","evidence":"siRNA knockdown with viral replication assay, miRNA target validation, and mouse brain expression analysis","pmids":["26676784"],"confidence":"Medium","gaps":["Mechanism by which SESTD1 supports replication unknown","Single-lab study","Whether lipid binding or Rho regulation underlies the viral phenotype untested"]},{"year":2019,"claim":"Established Sestd1 as a developmentally regulated synaptic protein whose loss reduces dendrite and synapse formation via dysregulated Rho-family GTPase signaling, linking it to the Rho-GAP BCR.","evidence":"Mouse knockout, subcellular fractionation and immunofluorescence, AMPA/NMDA EPSC recording, Co-IP/mass spectrometry from brain, and Rho GTPase activation assays","pmids":["29293918"],"confidence":"High","gaps":["Direct functional role of the SESTD1–BCR complex not dissected","How SESTD1 coordinates Rac1 vs RhoA regulation unclear","Mechanism of pre- to postsynaptic shift unknown"]},{"year":null,"claim":"How SESTD1's Ca2+-dependent lipid binding mechanistically integrates with its regulation of Rho-family GTPases across channel, developmental, and synaptic settings remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model connecting lipid-binding and spectrin domains to GTPase regulation","Whether a single biochemical activity unifies the TRPC, PCP, and synaptic roles is unknown","No defined direct catalytic activity on GTPases"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[1,2]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[3,5]}],"complexes":[],"partners":["TRPC4","TRPC5","VANGL2","DACT1","DVL2","RAC1","BCR"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q86VW0","full_name":"SEC14 domain and spectrin repeat-containing protein 1","aliases":["Huntingtin-interacting protein-like protein","Protein Solo"],"length_aa":696,"mass_kda":79.3,"function":"May act as the primary docking protein directing membrane turnover and assembly of the transient receptor potential channels TRPC4 and TRPC5. Binds phospholipids such as phosphatidylinositol monophosphates, phosphatidylinositol diphosphates (PIP2s) and phosphatidic acid, but not less polar lipids including phosphatidylcholine, phosphatidylserine, and phosphatidylinositol. The binding to PIP2s is calcium dependent. Might be involved in the plasma membrane localization of CTNNB1","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q86VW0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SESTD1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SESTD1","total_profiled":1310},"omim":[{"mim_id":"621011","title":"SEC14 AND SPECTRIN DOMAINS-CONTAINING PROTEIN 1; SESTD1","url":"https://www.omim.org/entry/621011"},{"mim_id":"607861","title":"DAPPER, ANTAGONIST OF BETA-CATENIN, 1; DACT1","url":"https://www.omim.org/entry/607861"},{"mim_id":"600533","title":"VANGL PLANAR CELL POLARITY PROTEIN 2; VANGL2","url":"https://www.omim.org/entry/600533"},{"mim_id":"301023","title":"MICRO RNA 532; MIR532","url":"https://www.omim.org/entry/301023"},{"mim_id":"300480","title":"TAK1-BINDING PROTEIN 3; TAB3","url":"https://www.omim.org/entry/300480"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Intermediate filaments","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SESTD1"},"hgnc":{"alias_symbol":["DKFZp434O0515","Solo"],"prev_symbol":[]},"alphafold":{"accession":"Q86VW0","domains":[{"cath_id":"3.40.525.10","chopping":"2-151","consensus_level":"high","plddt":82.4203,"start":2,"end":151},{"cath_id":"1.20.58.60","chopping":"290-494","consensus_level":"medium","plddt":91.2257,"start":290,"end":494},{"cath_id":"1.20.58","chopping":"524-686","consensus_level":"medium","plddt":88.5898,"start":524,"end":686},{"cath_id":"1.10.287","chopping":"166-183_202-277","consensus_level":"high","plddt":80.6676,"start":166,"end":277}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86VW0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86VW0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86VW0-F1-predicted_aligned_error_v6.png","plddt_mean":86.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SESTD1","jax_strain_url":"https://www.jax.org/strain/search?query=SESTD1"},"sequence":{"accession":"Q86VW0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86VW0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86VW0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86VW0"}},"corpus_meta":[{"pmid":"26503763","id":"PMC_26503763","title":"Genome-wide association study identifies SESTD1 as a novel risk gene for lithium-responsive bipolar disorder.","date":"2015","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/26503763","citation_count":64,"is_preprint":false},{"pmid":"26676784","id":"PMC_26676784","title":"Human MicroRNA miR-532-5p Exhibits Antiviral Activity against West Nile Virus via Suppression of Host Genes SESTD1 and TAB3 Required for Virus Replication.","date":"2015","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/26676784","citation_count":60,"is_preprint":false},{"pmid":"21624095","id":"PMC_21624095","title":"Integration of transient receptor potential canonical channels with lipids.","date":"2011","source":"Acta physiologica (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/21624095","citation_count":53,"is_preprint":false},{"pmid":"24756705","id":"PMC_24756705","title":"TRPC5.","date":"2014","source":"Handbook of experimental pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/24756705","citation_count":51,"is_preprint":false},{"pmid":"20164195","id":"PMC_20164195","title":"The phospholipid-binding protein SESTD1 is a novel regulator of the transient receptor potential channels TRPC4 and TRPC5.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20164195","citation_count":43,"is_preprint":false},{"pmid":"20352079","id":"PMC_20352079","title":"Genomic and geographic distribution of private SNPs and pathways in human populations.","date":"2009","source":"Personalized medicine","url":"https://pubmed.ncbi.nlm.nih.gov/20352079","citation_count":22,"is_preprint":false},{"pmid":"28194006","id":"PMC_28194006","title":"Genome-wide association study identifies SESTD1 as a novel risk gene for lithium-responsive bipolar disorder.","date":"2017","source":"Molecular 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TRPC4 and TRPC5 channels, associating via the channel's calmodulin- and inositol 1,4,5-trisphosphate receptor-binding (CIRB) domain. SESTD1 contains a lipid-binding SEC14-like domain and spectrin-type cytoskeleton interaction domains, binds multiple phospholipid species in vitro in a Ca2+-dependent manner, and is essential for efficient receptor-mediated activation of TRPC5.\",\n      \"method\": \"Yeast two-hybrid screen of human aortic cDNA library, co-immunoprecipitation, in vitro phospholipid-binding assays, functional (electrophysiological) studies, domain-mapping experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods in one study: Y2H identification, reciprocal Co-IP, in vitro lipid-binding assay with Ca2+ dependence, and functional TRPC5 activation assay; foundational mechanistic paper for this gene\",\n      \"pmids\": [\"20164195\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Sestd1 is a novel binding partner of both Vangl2 and Dact1 in the Wnt/Planar Cell Polarity (PCP) pathway. The Sestd1–Dact1 interface maps to the C-terminal region of Sestd1 and the N-terminal region of Dact1. Genetic knockout of Sestd1 in mice phenocopies Dact1 knockout (neural tube defects, shortened/curly tail, developmental malformations), and Sestd1 KO shows reciprocal genetic rescue with a semidominant Vangl2 mutation, placing Sestd1 in the PCP pathway upstream of or parallel to Vangl2. In cell-based assays, the Sestd1–Dact1 interaction induces Rho GTPase activation.\",\n      \"method\": \"Co-immunoprecipitation, domain-mapping, mouse knockout generation, genetic epistasis (Vangl2 semidominant allele rescue), Wnt pathway activity assays, cell-based Rho GTPase activation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, in vivo KO phenotyping, genetic epistasis with Vangl2 allele, and cell-based functional assay; multiple orthogonal methods\",\n      \"pmids\": [\"23696638\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Dvl2 forms complexes with Sestd1 independently of both Dact1 and Vangl2. In cell-based assays, Sestd1 does not alter Dvl2 activation of Wnt/β-catenin signaling, but Dvl2 enhances activation of Rho family GTPases by the Dact1–Sestd1 complex. Genetic experiments show that Dvl2 KO, recessive in wild-type background, causes dominant embryonic lethality in Sestd1 or Dact1 KO backgrounds, indicating genetic synergy distinct from the epistasis between Sestd1 and Dact1.\",\n      \"method\": \"Co-immunoprecipitation, cell-based β-catenin and Rho GTPase reporter assays, mouse double-KO genetic interaction analysis\",\n      \"journal\": \"Communicative & integrative biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP and cell-based assays combined with in vivo genetic synergy, single lab, complementary to PMID:23696638\",\n      \"pmids\": [\"24505507\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"SESTD1 negatively regulates dendritic spine density in hippocampal neurons by interfering with the interaction between Rac1 and its guanine nucleotide exchange factor Trio8. The SPEC1 domain of SESTD1 mediates interaction with Rac1. Overexpression of SESTD1 decreases spine density and miniature excitatory postsynaptic current (mEPSC) frequency; knockdown of SESTD1 increases spine density and mEPSC frequency. Transfection of the GEF domain of Trio8 rescues the SESTD1-mediated decrease in spine density.\",\n      \"method\": \"Overexpression and siRNA knockdown in cultured hippocampal neurons, co-immunoprecipitation (Rac1–SESTD1 interaction), domain deletion/mutation mapping (SPEC1), electrophysiology (mEPSC recording), rescue experiments with Trio8-GEF domain\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods: Co-IP for interaction, gain-of-function/loss-of-function in neurons, electrophysiology, and domain-specific rescue; comprehensive single-lab study\",\n      \"pmids\": [\"26272757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"SESTD1 is required for efficient West Nile virus (Kunjin strain) replication in human cells. siRNA depletion of SESTD1 reduced WNVKUN replication. miR-532-5p targets and downregulates SESTD1 expression, and this suppression mediates an antiviral host response.\",\n      \"method\": \"siRNA knockdown of SESTD1 in human cells with viral replication assay, miRNA target validation (luciferase/reporter assays implied, qRT-PCR), in vivo mouse brain expression analysis\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — siRNA loss-of-function with viral replication readout, miRNA target validation, replicated in mouse brain; single lab\",\n      \"pmids\": [\"26676784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Sestd1 is a synapse protein that shifts from the presynaptic to postsynaptic compartment as neurons mature postnatally in the mouse hippocampus. Conditional/global deletion of Sestd1 reduces dendrite arbors, spines, and excitatory synapses in hippocampal pyramidal neurons, with cell-autonomous reductions in both AMPA- and NMDA-mediated EPSCs. These deficits are associated with increased activation of Rac1 and RhoA. Co-immunoprecipitation and mass spectrometry identified BCR (Breakpoint Cluster Region), a Rho GTPase-activating protein (GAP), as a Sestd1 complex partner in brain tissue.\",\n      \"method\": \"Mouse genetic knockout, in vivo fractionation and immunofluorescence for synaptic localization, electrophysiology (AMPA- and NMDA-EPSC recording), co-immunoprecipitation from brain tissue coupled with mass spectrometry, Rho GTPase activation assays\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO with defined cellular phenotype, electrophysiology, subcellular fractionation with functional consequence, and Co-IP/MS for interactor identification; multiple orthogonal methods\",\n      \"pmids\": [\"29293918\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SESTD1 is a phospholipid-binding scaffold protein with a SEC14-like lipid-binding domain and spectrin-repeat cytoskeleton interaction domains that acts as a regulator of TRPC4/TRPC5 cation channels (via their CIRB domain), the Wnt/Planar Cell Polarity pathway (through complexes with Vangl2, Dact1, and Dvl2), and dendritic spine and excitatory synapse formation (by modulating Rho family GTPase activity via interactions with Rac1, BCR-GAP, and the GEF Trio8); its lipid binding is Ca2+-dependent, and loss of Sestd1 in mice leads to developmental defects, reduced dendrite arbors, fewer excitatory synapses, and decreased excitatory postsynaptic currents, while in human cells it is required for efficient West Nile virus replication.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SESTD1 is a Ca2+-dependent phospholipid-binding scaffold protein that couples membrane lipid signaling to cytoskeletal regulation and Rho-family GTPase control across ion channel, developmental, and synaptic contexts [#0, #1, #5]. Through its SEC14-like lipid-binding domain and spectrin-type cytoskeleton interaction domains, it binds multiple phospholipid species in a Ca2+-dependent manner and associates with the CIRB domain of TRPC4 and TRPC5 channels, where it is required for efficient receptor-mediated TRPC5 activation [#0]. In the Wnt/Planar Cell Polarity pathway, SESTD1 binds Vangl2 and Dact1 and, through the Dact1 interaction, activates Rho GTPases; mouse knockout phenocopies Dact1 loss with neural tube and tail defects and shows genetic interactions with Vangl2 and Dvl2, the latter potentiating Rho activation by the Dact1–Sestd1 complex [#1, #2]. In neurons, SESTD1 acts as a brake on excitatory connectivity: its SPEC1 domain binds Rac1 and interferes with the Rac1–Trio8 GEF interaction to limit dendritic spine density and mEPSC frequency [#3], and loss of Sestd1 in mice reduces dendrite arbors, spines, and excitatory synapses with elevated Rac1 and RhoA activation, in part via complex formation with the Rho-GAP BCR [#5]. SESTD1 is also required for efficient West Nile virus (Kunjin) replication in human cells and is targeted by the antiviral miRNA miR-532-5p [#4].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established SESTD1 as a TRPC4/TRPC5 channel-associated, Ca2+-dependent lipid-binding protein, defining its core biochemical identity and a functional role in channel activation.\",\n      \"evidence\": \"Yeast two-hybrid screen, reciprocal Co-IP, in vitro phospholipid-binding assays, domain mapping, and electrophysiology in heterologous cells\",\n      \"pmids\": [\"20164195\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Lipid-binding specificity in vivo not resolved\", \"No structural model of the SEC14-like or spectrin domains\", \"Whether lipid binding gates TRPC5 regulation directly was not dissected\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Placed Sestd1 in the Wnt/PCP pathway as a Vangl2- and Dact1-binding partner that activates Rho GTPases, connecting it to morphogenetic signaling.\",\n      \"evidence\": \"Reciprocal Co-IP, domain mapping, mouse knockout phenotyping, genetic epistasis with a Vangl2 semidominant allele, and cell-based Rho GTPase assays\",\n      \"pmids\": [\"23696638\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which the Dact1–Sestd1 interface activates Rho not defined\", \"Direct GEF/GAP not identified in this context\", \"Whether lipid binding contributes to PCP function untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Distinguished a Dvl2 branch from the Dact1 axis, showing Dvl2 potentiates Rho activation by the Dact1–Sestd1 complex without affecting β-catenin signaling, and revealing genetic synergy.\",\n      \"evidence\": \"Co-IP, cell-based β-catenin and Rho GTPase reporter assays, and mouse double-knockout genetic interaction analysis\",\n      \"pmids\": [\"24505507\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab study\", \"Biochemical basis of Dvl2-enhanced Rho activation unresolved\", \"Compartment where the complexes form not defined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined a synaptic mechanism in which SESTD1 limits spine density by disrupting the Rac1–Trio8 GEF interaction, identifying the SPEC1 domain as the Rac1-binding module.\",\n      \"evidence\": \"Overexpression and siRNA knockdown in hippocampal neurons, Co-IP, SPEC1 domain mapping, mEPSC recording, and Trio8-GEF rescue\",\n      \"pmids\": [\"26272757\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How SESTD1 physically blocks Rac1–Trio8 not structurally defined\", \"Link to lipid-binding or channel functions untested\", \"In vivo confirmation pending in this study\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified SESTD1 as a host factor required for efficient West Nile virus replication and a target of antiviral miR-532-5p, extending its roles to virus–host interaction.\",\n      \"evidence\": \"siRNA knockdown with viral replication assay, miRNA target validation, and mouse brain expression analysis\",\n      \"pmids\": [\"26676784\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which SESTD1 supports replication unknown\", \"Single-lab study\", \"Whether lipid binding or Rho regulation underlies the viral phenotype untested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established Sestd1 as a developmentally regulated synaptic protein whose loss reduces dendrite and synapse formation via dysregulated Rho-family GTPase signaling, linking it to the Rho-GAP BCR.\",\n      \"evidence\": \"Mouse knockout, subcellular fractionation and immunofluorescence, AMPA/NMDA EPSC recording, Co-IP/mass spectrometry from brain, and Rho GTPase activation assays\",\n      \"pmids\": [\"29293918\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct functional role of the SESTD1–BCR complex not dissected\", \"How SESTD1 coordinates Rac1 vs RhoA regulation unclear\", \"Mechanism of pre- to postsynaptic shift unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SESTD1's Ca2+-dependent lipid binding mechanistically integrates with its regulation of Rho-family GTPases across channel, developmental, and synaptic settings remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model connecting lipid-binding and spectrin domains to GTPase regulation\", \"Whether a single biochemical activity unifies the TRPC, PCP, and synaptic roles is unknown\", \"No defined direct catalytic activity on GTPases\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [3, 5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TRPC4\", \"TRPC5\", \"Vangl2\", \"Dact1\", \"Dvl2\", \"Rac1\", \"BCR\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}