{"gene":"DOCK4","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":2003,"finding":"DOCK4 specifically activates Rap1 GTPase, enhancing formation of adherens junctions; a recurrent missense mutant found in human prostate and ovarian cancers is defective in Rap1 activation; wild-type DOCK4 rescues the engulfment defect of C. elegans ced-5 mutants but the cancer-associated mutant does not","method":"GTPase activation assays, C. elegans genetic rescue, soft agar/invasion assays with wild-type vs. mutant DOCK4","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (biochemical GEF assay, genetic rescue, in vivo tumor suppression), replicated across systems","pmids":["12628187"],"is_preprint":false},{"year":2006,"finding":"Dock4 is regulated upstream by the small GTPase RhoG and its effector ELMO; active RhoG induces translocation of the Dock4-ELMO complex from the cytoplasm to the plasma membrane and enhances Dock4/ELMO-dependent Rac1 activation and cell migration; Dock4 knockdown in NIH3T3 cells reduces cell migration","method":"Co-immunoprecipitation, subcellular fractionation/imaging, Rac1 activation assay (GST-PAK pulldown), siRNA knockdown with migration assay","journal":"Experimental cell research","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, localization experiment with functional consequence, clean KD phenotype, multiple orthogonal methods in one study","pmids":["17027967"],"is_preprint":false},{"year":2008,"finding":"DOCK4 mediates Wnt-induced Rac activation in the canonical Wnt/β-catenin pathway by interacting with the β-catenin degradation complex (APC, Axin, GSK3β); this interaction enhances β-catenin stability and Axin degradation; GSK3β phosphorylates DOCK4, which enhances Wnt-induced Rac activation; DOCK4 is required for Wnt/β-catenin activity in vivo in zebrafish","method":"Co-immunoprecipitation, in vitro kinase assay, TCF reporter assay, zebrafish Wnt reporter model, β-catenin stability assays","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1-2 — biochemical interaction mapping, kinase assay, in vivo genetic validation in zebrafish, multiple orthogonal methods","pmids":["18641688"],"is_preprint":false},{"year":2008,"finding":"Dock4 promotes dendritic growth and branching in hippocampal neurons via Rac activation; Dock4 forms a complex with ELMO2 and CrkII in hippocampal neurons; the C-terminal Crk-binding region of Dock4 is required for morphological effects; knockdown reduces dendritic growth and branching while overexpression with ELMO2 enhances it","method":"shRNA knockdown, overexpression, Co-immunoprecipitation, Rac activation assay, morphometric analysis of cultured hippocampal neurons","journal":"Journal of neuroscience research","confidence":"High","confidence_rationale":"Tier 2 — clean KD/OE with defined cellular phenotype, Co-IP of complex, Rac activation assay, domain mapping, moderate strength","pmids":["18615735"],"is_preprint":false},{"year":2006,"finding":"A novel DOCK4 isoform (DOCK4-Ex49) is expressed in brain, eye, and inner ear; it localizes to stereocilia hair bundles in the inner ear; it binds nucleotide-free Rac and activates Rac as effectively as DOCK2; it interacts with the PDZ-domain protein harmonin (USH1C) identified by yeast two-hybrid","method":"Yeast two-hybrid, immunostaining with isoform-specific antibody, Rac binding/activation assay","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct localization experiment with mechanistic context, biochemical Rac binding assay, but interaction validated only by Y2H","pmids":["16464467"],"is_preprint":false},{"year":2008,"finding":"DOCK4 and its splicing variant bind PIP3 through the DHR-1 domain, suggesting regulation of DOCK4 by phosphoinositides","method":"PIP3-analog bead binding assay, deletion mutant mapping","journal":"IUBMB life","confidence":"Medium","confidence_rationale":"Tier 2 — direct biochemical binding assay with domain mapping, single lab, single method","pmids":["18459162"],"is_preprint":false},{"year":2013,"finding":"Dock4 is concentrated in dendritic spines and promotes spine formation via interaction with the actin-binding protein cortactin; a GEF-deficient mutant and a mutant lacking the cortactin-binding region both fail to rescue spine density upon Dock4 knockdown; cortactin knockdown suppresses Dock4-mediated spine formation","method":"shRNA knockdown and rescue with domain mutants, Co-immunoprecipitation, confocal imaging, dendritic spine density quantification","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal KD, domain-mapping rescue experiments, Co-IP, multiple orthogonal methods","pmids":["23536706"],"is_preprint":false},{"year":2014,"finding":"Dock4 forms a complex with SH3YL1 (a phosphoinositide-binding protein) via the C-terminal proline-rich region of Dock4; SH3YL1 interaction promotes Dock4-mediated Rac1 activation and cell migration; phosphoinositide-binding domain mutations in SH3YL1 disrupt its ability to promote Dock4-mediated migration; SH3YL1 depletion suppresses cell migration","method":"Co-immunoprecipitation, Rac1 activation assay, domain-mapping, siRNA knockdown, cell migration assay","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP, functional Rac1 assay, domain mutagenesis, KD phenotype; single lab","pmids":["24508479"],"is_preprint":false},{"year":2015,"finding":"TGF-β induces DOCK4 expression via the Smad pathway in lung adenocarcinoma cells; DOCK4 induction mediates TGF-β's pro-metastatic effects by enhancing tumor cell extravasation through Rac1 activation, without affecting EMT","method":"Smad pathway inhibition/activation, DOCK4 knockdown/overexpression, Rac1 activation assay, in vivo extravasation assays, cell motility/invasion assays","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — pathway epistasis (TGF-β/Smad→DOCK4→Rac1), in vivo validation, multiple orthogonal methods","pmids":["25644601"],"is_preprint":false},{"year":2015,"finding":"DOCK4 knockdown in primary marrow CD34+ stem cells leads to decreased erythroid colony formation and increased apoptosis; reduced DOCK4 leads to disruption of F-actin filament network in erythroblasts via decreased RAC1 GTPase activation, leading to increased phosphorylation of the actin-stabilizing protein ADDUCIN","method":"siRNA knockdown in primary CD34+ cells, erythroid colony assay, F-actin quantification, RAC1 activation assay, ADDUCIN phosphorylation western blot, DOCK4 re-expression in MDS patient erythroblasts","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean KD with defined cellular phenotype, RAC1 activity measurement, downstream effector phosphorylation, rescue experiment","pmids":["26578796"],"is_preprint":false},{"year":2017,"finding":"DOCK4 promotes nuclear β-catenin accumulation in GBM progenitor cells via increased GSK3β activity in a feed-forward mechanism; nuclear β-catenin then induces miR-302 expression, which represses cyclin D1 and stemness features, resulting in anti-proliferative effects; DOCK4 overexpression suppresses self-renewal and tumorigenicity of GBM stem-like cells","method":"DOCK4 overexpression, GSK3β activity assay, β-catenin nuclear fractionation, miR-302 reporter, cyclin D1 western blot, neurosphere assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple biochemical readouts, functional cellular assays; single lab","pmids":["28925399"],"is_preprint":false},{"year":2019,"finding":"SR-B1 recruits DOCK4 via an eight-amino-acid cytoplasmic domain of the receptor; DOCK4 promotes internalization of SR-B1 and LDL transcytosis across endothelial monolayers by coupling LDL binding to SR-B1 with activation of RAC1","method":"Co-immunoprecipitation, domain mapping (SR-B1 cytoplasmic tail mutants), Rac1 activation assay, LDL transcytosis assay across endothelial monolayers, SR-B1/DOCK4 colocalization in vesicles in vivo","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 — reconstituted transcytosis assay, domain mapping with mutagenesis, Rac1 activation, in vivo colocalization; replicated in multiple systems","pmids":["31019307"],"is_preprint":false},{"year":2019,"finding":"Dock4 deficiency in mice reduces Rac1 activity in hippocampus, causing downregulation of global protein synthesis and diminished AMPA and NMDA receptor subunit expression; conditional Dock4 deletion in CA1 neurons attenuates excitatory synaptic transmission and decreases spine density; Rac1 replenishment in CA1 restores synaptic transmission and corrects social deficits; NMDA receptor pharmacological activation also restores social novelty preference","method":"Dock4 KO and conditional KO mice, Rac1 activation assay, electrophysiology, spine density analysis, western blot for receptor subunits, viral Rac1 rescue, pharmacological NMDA activation","journal":"Molecular psychiatry","confidence":"High","confidence_rationale":"Tier 2 — clean KO/conditional KO with defined synaptic phenotype, Rac1 activity measurement, rescue experiments, multiple orthogonal methods","pmids":["31388105"],"is_preprint":false},{"year":2019,"finding":"Reduced DOCK4 expression in hematopoietic stem cells leads to increased tyrosine phosphorylation of LYN kinase and phosphatases SHIP1 (INPP5D) and SHP1 (PTPN6); LYN kinase targets SHIP1 and SHP1 as substrates; these signaling alterations increase migration and impede HSC differentiation; pharmacological SHP1 inhibition reverses erythroid differentiation block in DOCK4-low/-7q MDS cells","method":"Phosphoproteomics, siRNA knockdown, kinase substrate assay, migration assay, erythroid differentiation assay, pharmacological inhibition","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — phosphoproteomics plus functional validation; single lab but multiple orthogonal approaches","pmids":["31308061"],"is_preprint":false},{"year":2020,"finding":"Two DOCK4 variants (Exon27-52 deletion producing Dock4-945VS, and missense R853H) show decreased ability to activate both Rac1 and Rap1, are dysfunctional for cell morphology/cytoskeleton regulation, and have compromised function in promoting neurite outgrowth and dendritic spine formation; R853H partially loses ability to promote excitatory synaptic transmission while 945VS totally loses it","method":"GTPase activation assay (Rac1, Rap1), cell morphology analysis, neurite outgrowth assay in Neuro-2a cells and hippocampal neurons, spine density quantification, electrophysiological recordings","journal":"Frontiers in cellular neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 — direct in vitro GEF assay for both Rac1 and Rap1, functional neurite/spine assays, electrophysiology; multiple orthogonal methods","pmids":["32009906"],"is_preprint":false},{"year":2020,"finding":"DOCK4 overexpression increases cytotrophoblast (CTB) invasiveness, consistent with the placenta accreta spectrum (PAS) over-invasion phenotype; DOCK4 mRNA is the most highly upregulated molecule in PAS CTBs compared to normal depth-invading CTBs","method":"Global gene expression comparison, DOCK4 overexpression with invasion assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 3 — overexpression with functional invasion assay; limited mechanistic dissection","pmids":["32576693"],"is_preprint":false},{"year":2022,"finding":"DOCK4 deficiency in mice causes pulmonary hemorrhage, incomplete smooth muscle coverage in pulmonary vessels, increased basal microvascular permeability, and impaired S1P-induced reversal of thrombin-induced permeability; DOCK4 rapidly translocates to the cell periphery (detergent-insoluble fraction) upon S1P treatment; DOCK4 absence prevents S1P-induced Rac1 activation; DOCK4-silenced cells exhibit enhanced RhoA activation; DOCK4 maintains AJs by balancing RhoA and Rac1 activity","method":"DOCK4-deficient mice (in vivo hemorrhage, permeability), DOCK4 silencing and reconstitution in HPAEC, subcellular fractionation, Rac1/RhoA activation assays, endothelial permeability assay","journal":"Arteriosclerosis, thrombosis, and vascular biology","confidence":"High","confidence_rationale":"Tier 2 — KO mouse with defined vascular phenotype, KD/reconstitution in human cells, direct GTPase activity measurements, localization experiment with functional consequence","pmids":["35477279"],"is_preprint":false},{"year":2022,"finding":"Dock4 knockdown in cochlear hair cells causes hair bundle deficits, increased oxidative stress, and progressive HC apoptosis; mechanistically, Rac1/β-catenin signaling is downregulated in Dock4 KD cochleae, causing disorganized stereocilia and increased oxidative stress","method":"piggyBac transposon-mediated Dock4 KD mice, ABR/DPOAE hearing tests, hair bundle morphology, Rac1 and β-catenin western blot/immunofluorescence, oxidative stress markers, HC apoptosis assay","journal":"Fundamental research","confidence":"Medium","confidence_rationale":"Tier 2 — KD mouse with defined phenotype plus molecular pathway readout; single lab","pmids":["38933554"],"is_preprint":false},{"year":2024,"finding":"Brain endothelial cells activate EGFR signaling in triple-negative breast cancer cells via soluble factors, and this activation occurs via DOCK4 (RAC1 GEF); DOCK4 is required for breast cancer cell extravasation to the brain in vivo; DOCK4 knockdown inhibits elongated morphology preceding intercalation into brain endothelium; DOCK4 and DOCK9 together mediate paracrine stimulation of mesenchymal-like morphology via RAC1 and CDC42","method":"DOCK4 knockdown, in vivo brain extravasation assay, cell morphology analysis, EGFR inhibitor (Afatinib) experiments, RAC1/CDC42 activation assays","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo extravasation assay plus mechanistic KD; single lab","pmids":["38762624"],"is_preprint":false},{"year":2024,"finding":"HIF2α functions in normoxia in kidney epithelial cells to induce Dock4/Rac1/Pak1 signaling, which mediates stability and compaction of E-cadherin at nascent adherens junctions; HIF2α- or Dock4-deficient cells show aberrant cyst morphogenesis in 3D cultures","method":"HIF2α and Dock4 siRNA knockdown, Rac1/Pak1 activation assays, E-cadherin localization imaging, 3D cyst morphogenesis assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis (HIF2α→Dock4→Rac1/Pak1), functional 3D assay, GTPase activation measurement; single lab","pmids":["38802496"],"is_preprint":false},{"year":2024,"finding":"Dock4 in dorsal root ganglion neurons interacts with Nav1.7 and mediates its trafficking from the membrane to the cytoplasm; Dock4 acts as an adaptor binding the motor protein Dynein to form a Dynein/DOCK4/Nav1.7 complex, where Dynein provides mechanical force for Nav1.7 trafficking; DOCK4 expression in DRG neurons is regulated by histone H4K8 lactylation; DOCK4 deficiency increases heat nociception","method":"Co-immunoprecipitation, proximity ligation assay, Nav1.7 trafficking assay, Dock4 KD in DRG (mice and nonhuman primates), histone lactylation ChIP, nociception behavioral assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 — Co-IP of ternary complex, functional trafficking assay, in vivo KD in two species, epigenetic regulation mapping; multiple orthogonal methods","pmids":["40759894"],"is_preprint":false},{"year":2024,"finding":"Heterozygous loss-of-function missense variants in DOCK4 impair neurite outgrowth in Neuro-2A cells; Dock4 knockout Neuro-2A cells also exhibit defects in neurite outgrowth; molecular modeling suggests missense variants affect the globular structure of DOCK4","method":"In vitro functional expression of DOCK4 variants in Neuro-2A cells (neurite outgrowth assay), Dock4 KO cells, molecular modeling","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct functional assay in KO and mutant overexpression; single lab","pmids":["38526744"],"is_preprint":false},{"year":2025,"finding":"THEMIS2 acts as a molecular scaffold that recruits TBK1 to DOCK4, facilitating phosphorylation of DOCK4 at serine 1787 (S1787); this post-translational modification enables DOCK4 to engage with CRKII, subsequently triggering Rap1 signaling activation and promoting ovarian cancer metastasis","method":"Immunoprecipitation-mass spectrometry, GST pull-down assay for active Rap1 (Rap1-GTP), co-immunoprecipitation, phospho-site mapping, wound healing and invasion assays, in vivo metastasis model","journal":"Cellular oncology","confidence":"Medium","confidence_rationale":"Tier 2 — IP-MS interaction identification, biochemical Rap1 activation assay, phospho-site identification, functional rescue; single lab","pmids":["40227532"],"is_preprint":false},{"year":2024,"finding":"Dock4 facilitates excitatory synaptic transmission in spinal dorsal horn neurons by promoting GluN2B expression at the synaptic site and synaptogenesis; Dock4 knockdown prevents dendritic growth, synaptogenesis, and increased excitatory postsynaptic currents in a spinal nerve ligation neuropathic pain model","method":"Dock4 RNAi knockdown, whole-cell patch clamp electrophysiology in spinal cord slices, GluN2B immunofluorescence/western blot, Rac1 activation assay, dendritic spine analysis in cultured dorsal spinal neurons","journal":"Frontiers in molecular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — clean KD with electrophysiology and spine morphology readouts; single lab","pmids":["39282658"],"is_preprint":false},{"year":2021,"finding":"USP36 directly binds DOCK4 and mediates its deubiquitination, thereby stabilizing DOCK4; stabilized DOCK4 activates Wnt/β-catenin signaling and promotes EMT in diabetic renal tubular epithelial cells","method":"Co-immunoprecipitation, ubiquitination assay, USP36 overexpression/knockdown with DOCK4 stability readout, EMT marker western blot","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and deubiquitination assay; single lab, limited mechanistic dissection downstream","pmids":["33968925"],"is_preprint":false}],"current_model":"DOCK4 is an unconventional guanine nucleotide exchange factor (GEF) that activates Rac1 and Rap1 GTPases through its DHR-2 domain (regulated by PIP3 binding at DHR-1, by RhoG/ELMO upstream inputs, by GSK3β phosphorylation, and by TBK1-mediated phosphorylation at S1787); it functions as a scaffold in multiple signaling pathways including Wnt/β-catenin (by interacting with the APC/Axin/GSK3β degradation complex), TGF-β/Smad-driven metastasis, and SR-B1-mediated LDL transcytosis; in neurons it localizes to dendritic spines where it promotes spine formation and excitatory synaptic transmission via Rac1 activation and cortactin interaction, and it forms a Dynein/DOCK4/Nav1.7 complex in DRG neurons to regulate Nav1.7 membrane trafficking and heat nociception; in endothelial cells it maintains adherens junction integrity by balancing Rac1 and RhoA activities; and its loss in hematopoietic progenitors impairs erythropoiesis through reduced RAC1 activity, disrupted F-actin, and increased ADDUCIN phosphorylation, with downstream LYN/SHP1/SHIP1 signaling perturbation."},"narrative":{"teleology":[{"year":2003,"claim":"Establishing DOCK4 as a GEF for Rap1 that promotes adherens junctions and functions as a tumor suppressor resolved its basic enzymatic identity and linked it to cell adhesion and cancer.","evidence":"GTPase activation assays, C. elegans ced-5 rescue, and soft agar/invasion assays with cancer-associated mutant in human cell lines","pmids":["12628187"],"confidence":"High","gaps":["Rac1 GEF activity not yet demonstrated","structural basis for Rap1 specificity unknown","in vivo tumor suppressor role not validated in mammalian models"]},{"year":2006,"claim":"Identifying RhoG/ELMO as upstream activators that translocate DOCK4 to the membrane for Rac1 activation established DOCK4 as a dual Rac1/Rap1 GEF regulated by a GTPase cascade, answering how its membrane recruitment and activation are controlled.","evidence":"Co-immunoprecipitation, subcellular fractionation, Rac1-GTP pulldown, and siRNA knockdown with migration assay in NIH3T3 cells; parallel identification of a brain-specific isoform binding Rac and harmonin","pmids":["17027967","16464467"],"confidence":"High","gaps":["ELMO isoform specificity not resolved","harmonin interaction confirmed only by Y2H","structural basis of RhoG-ELMO-DOCK4 complex unknown"]},{"year":2008,"claim":"Demonstrating that DOCK4 integrates into the Wnt/β-catenin destruction complex (APC/Axin/GSK3β) and is phosphorylated by GSK3β to enhance Rac activation revealed a non-canonical role as a scaffold linking Wnt signaling to cytoskeletal remodeling, while PIP3 binding via DHR-1 established a lipid-dependent regulatory mechanism.","evidence":"Co-IP of DOCK4 with APC/Axin/GSK3β, in vitro kinase assay, TCF reporter in zebrafish; PIP3-analog bead binding with deletion mapping; neurite outgrowth assays in hippocampal neurons with ELMO2/CrkII complex","pmids":["18641688","18459162","18615735"],"confidence":"High","gaps":["Phosphorylation site on DOCK4 by GSK3β not mapped","relative contribution of PIP3 vs. ELMO to membrane targeting unclear","in vivo Wnt phenotype not tested in mammalian models at this stage"]},{"year":2013,"claim":"Showing that DOCK4 concentrates in dendritic spines and requires both GEF activity and cortactin binding to promote spine formation established the molecular mechanism by which DOCK4 controls synaptic structure.","evidence":"shRNA knockdown and rescue with GEF-dead and cortactin-binding-deficient mutants, Co-IP, confocal spine density quantification in hippocampal neurons","pmids":["23536706"],"confidence":"High","gaps":["Whether cortactin interaction is direct or bridged unknown","electrophysiological consequences not assessed","upstream signals activating DOCK4 at spines not identified"]},{"year":2015,"claim":"Identifying DOCK4 as a TGF-β/Smad transcriptional target that drives tumor extravasation via Rac1, and demonstrating its requirement for erythropoiesis via RAC1-dependent actin organization, expanded DOCK4 function beyond neurons to cancer metastasis and hematopoiesis.","evidence":"Smad pathway epistasis and in vivo extravasation assays in lung adenocarcinoma; siRNA in CD34+ cells with erythroid colony assay, F-actin/ADDUCIN phosphorylation readouts, and rescue in MDS erythroblasts","pmids":["25644601","26578796"],"confidence":"High","gaps":["Direct transcriptional regulation by Smad not confirmed by ChIP","specific DOCK4 domains required for erythroid function not mapped","relationship between Rap1 vs. Rac1 activation in erythropoiesis unclear"]},{"year":2019,"claim":"Discovering that SR-B1 recruits DOCK4 via its cytoplasmic tail to drive LDL transcytosis through Rac1 activation revealed a receptor-coupled GEF mechanism in endothelial lipid transport, while conditional Dock4 KO in hippocampal CA1 neurons established that DOCK4 controls global protein synthesis, glutamate receptor expression, and social behavior via Rac1.","evidence":"Co-IP with SR-B1 tail mutants, LDL transcytosis assay, in vivo colocalization; Dock4 conditional KO mice with electrophysiology, spine analysis, Rac1 viral rescue, NMDA pharmacological rescue; phosphoproteomics in hematopoietic cells showing LYN/SHP1/SHIP1 perturbation","pmids":["31019307","31388105","31308061"],"confidence":"High","gaps":["Whether DOCK4 GEF activity is required for SR-B1 coupling not tested with GEF-dead mutant","how DOCK4 controls global translation machinery not resolved","LYN/SHP1 pathway connection to Rac1 unclear"]},{"year":2022,"claim":"Demonstrating that DOCK4 maintains endothelial barrier integrity by balancing Rac1 and RhoA upon S1P stimulation, with DOCK4-deficient mice exhibiting pulmonary hemorrhage, established its vascular homeostatic function and the RhoA-counterbalancing mechanism.","evidence":"DOCK4-deficient mice with hemorrhage/permeability phenotypes, DOCK4 silencing and reconstitution in HPAEC, Rac1/RhoA activation assays, subcellular fractionation upon S1P treatment","pmids":["35477279"],"confidence":"High","gaps":["Whether DOCK4 directly inhibits RhoA or acts indirectly via Rac1 not resolved","S1P receptor isoform specificity for DOCK4 recruitment unknown","role in other vascular beds not tested"]},{"year":2024,"claim":"Identifying DOCK4 as a scaffold in a Dynein/DOCK4/Nav1.7 ternary complex that mediates Nav1.7 membrane trafficking in DRG neurons, regulated by histone H4K8 lactylation, revealed a GEF-independent adaptor function and an epigenetic control layer for DOCK4 expression in pain signaling.","evidence":"Co-IP and proximity ligation assay for ternary complex, Nav1.7 trafficking assay, Dock4 KD in mice and nonhuman primates, histone lactylation ChIP, nociception behavioral assays","pmids":["40759894"],"confidence":"High","gaps":["Whether GEF activity contributes to Nav1.7 trafficking not tested","lactylation writers/erasers controlling DOCK4 locus not identified","applicability to other ion channels unknown"]},{"year":2025,"claim":"Revealing that TBK1 phosphorylates DOCK4 at S1787 (scaffolded by THEMIS2) to enable CRKII engagement and Rap1 activation in ovarian cancer metastasis provided the first mapped phospho-regulatory switch controlling DOCK4's Rap1 GEF output.","evidence":"IP-mass spectrometry, phospho-site mapping, GST-Rap1 pulldown, Co-IP, in vivo metastasis model","pmids":["40227532"],"confidence":"Medium","gaps":["Whether S1787 phosphorylation also regulates Rac1 activation unknown","structural basis for phospho-dependent CRKII binding not resolved","single lab finding awaiting independent replication"]},{"year":null,"claim":"Key unresolved questions include the structural basis for DOCK4's dual Rac1/Rap1 specificity, the relative contributions of GEF-dependent versus GEF-independent (scaffolding) functions across tissues, and how tissue-specific isoforms and post-translational modifications partition DOCK4 among its diverse signaling outputs.","evidence":"","pmids":[],"confidence":"High","gaps":["No crystal or cryo-EM structure of DOCK4 DHR-2 with Rac1 or Rap1","GEF-independent adaptor functions not systematically separated from GEF activity","isoform-specific functions in inner ear and brain not fully delineated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,8,9,11,14,16,22]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[20,22]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,11,16]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[6,9]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[11]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,2,8,11,16,19,22]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[0,16,19]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[3,6,12,23]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[8,18,22]}],"complexes":["DOCK4/ELMO/CrkII","Dynein/DOCK4/Nav1.7","APC/Axin/GSK3β destruction complex"],"partners":["ELMO2","CRKII","SCARB1","CORT","SH3YL1","THEMIS2","TBK1","USP36"],"other_free_text":[]},"mechanistic_narrative":"DOCK4 is an atypical guanine nucleotide exchange factor (GEF) that activates Rac1 and Rap1 GTPases to regulate cytoskeletal dynamics, cell adhesion, and migration across diverse tissues. Its DHR-2 domain catalyzes nucleotide exchange on Rac1 and Rap1, while the DHR-1 domain binds PIP3 for membrane targeting; upstream activation is mediated by RhoG/ELMO-dependent translocation to the plasma membrane, GSK3β phosphorylation in the Wnt/β-catenin pathway, and TBK1-mediated phosphorylation at S1787 that enables CRKII engagement and Rap1 signaling [PMID:12628187, PMID:17027967, PMID:18459162, PMID:18641688, PMID:40227532]. In neurons, DOCK4 localizes to dendritic spines where it promotes spine formation and excitatory synaptic transmission through Rac1-dependent cortactin interaction and regulation of NMDA/AMPA receptor subunit expression; it also functions as a scaffold forming a Dynein/DOCK4/Nav1.7 complex in DRG neurons to control Nav1.7 membrane trafficking and heat nociception [PMID:23536706, PMID:31388105, PMID:40759894]. Beyond the nervous system, DOCK4 maintains endothelial adherens junction integrity by balancing Rac1 and RhoA activities, couples SR-B1 to LDL transcytosis via Rac1 activation in endothelial cells, supports erythropoiesis through RAC1-dependent F-actin organization, and mediates TGF-β/Smad-driven tumor cell extravasation [PMID:35477279, PMID:31019307, PMID:26578796, PMID:25644601]."},"prefetch_data":{"uniprot":{"accession":"Q8N1I0","full_name":"Dedicator of cytokinesis protein 4","aliases":[],"length_aa":1966,"mass_kda":225.2,"function":"Functions as a guanine nucleotide exchange factor (GEF) that promotes the exchange of GDP to GTP, converting inactive GDP-bound small GTPases into their active GTP-bound form (PubMed:12628187, PubMed:16464467). Involved in regulation of adherens junction between cells (PubMed:12628187). Plays a role in cell migration (PubMed:20679435) Has a higher guanine nucleotide exchange factor activity compared to other isoforms","subcellular_location":"Cell membrane; Cell projection; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q8N1I0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DOCK4","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/DOCK4","total_profiled":1310},"omim":[{"mim_id":"618871","title":"RHO GUANINE NUCLEOTIDE EXCHANGE FACTOR 16; ARHGEF16","url":"https://www.omim.org/entry/618871"},{"mim_id":"618191","title":"CEA CELL ADHESION MOLECULE 21; CEACAM21","url":"https://www.omim.org/entry/618191"},{"mim_id":"617314","title":"SH3 DOMAIN- AND SYLF DOMAIN-CONTAINING PROTEIN 1; SH3YL1","url":"https://www.omim.org/entry/617314"},{"mim_id":"607679","title":"DEDICATOR OF CYTOKINESIS 4; DOCK4","url":"https://www.omim.org/entry/607679"},{"mim_id":"606421","title":"ENGULFMENT AND CELL MOTILITY GENE 2; ELMO2","url":"https://www.omim.org/entry/606421"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Approved"},{"location":"Golgi apparatus","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in 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Disorder?","date":"2025","source":"Developmental neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/40790933","citation_count":0,"is_preprint":false},{"pmid":"39282658","id":"PMC_39282658","title":"Dock4 contributes to neuropathic pain by regulating spinal synaptic plasticity in mice.","date":"2024","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/39282658","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":25259,"output_tokens":6508,"usd":0.086698},"stage2":{"model":"claude-opus-4-6","input_tokens":10208,"output_tokens":3304,"usd":0.20046},"total_usd":0.287158,"stage1_batch_id":"msgbatch_0118RScg3WGaGkaZRtWZbtce","stage2_batch_id":"msgbatch_01Cpfzvtbj42aqp5oYZ5Te2s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"DOCK4 specifically activates Rap1 GTPase, enhancing formation of adherens junctions; a recurrent missense mutant found in human prostate and ovarian cancers is defective in Rap1 activation; wild-type DOCK4 rescues the engulfment defect of C. elegans ced-5 mutants but the cancer-associated mutant does not\",\n      \"method\": \"GTPase activation assays, C. elegans genetic rescue, soft agar/invasion assays with wild-type vs. mutant DOCK4\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (biochemical GEF assay, genetic rescue, in vivo tumor suppression), replicated across systems\",\n      \"pmids\": [\"12628187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Dock4 is regulated upstream by the small GTPase RhoG and its effector ELMO; active RhoG induces translocation of the Dock4-ELMO complex from the cytoplasm to the plasma membrane and enhances Dock4/ELMO-dependent Rac1 activation and cell migration; Dock4 knockdown in NIH3T3 cells reduces cell migration\",\n      \"method\": \"Co-immunoprecipitation, subcellular fractionation/imaging, Rac1 activation assay (GST-PAK pulldown), siRNA knockdown with migration assay\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, localization experiment with functional consequence, clean KD phenotype, multiple orthogonal methods in one study\",\n      \"pmids\": [\"17027967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"DOCK4 mediates Wnt-induced Rac activation in the canonical Wnt/β-catenin pathway by interacting with the β-catenin degradation complex (APC, Axin, GSK3β); this interaction enhances β-catenin stability and Axin degradation; GSK3β phosphorylates DOCK4, which enhances Wnt-induced Rac activation; DOCK4 is required for Wnt/β-catenin activity in vivo in zebrafish\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, TCF reporter assay, zebrafish Wnt reporter model, β-catenin stability assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — biochemical interaction mapping, kinase assay, in vivo genetic validation in zebrafish, multiple orthogonal methods\",\n      \"pmids\": [\"18641688\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Dock4 promotes dendritic growth and branching in hippocampal neurons via Rac activation; Dock4 forms a complex with ELMO2 and CrkII in hippocampal neurons; the C-terminal Crk-binding region of Dock4 is required for morphological effects; knockdown reduces dendritic growth and branching while overexpression with ELMO2 enhances it\",\n      \"method\": \"shRNA knockdown, overexpression, Co-immunoprecipitation, Rac activation assay, morphometric analysis of cultured hippocampal neurons\",\n      \"journal\": \"Journal of neuroscience research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KD/OE with defined cellular phenotype, Co-IP of complex, Rac activation assay, domain mapping, moderate strength\",\n      \"pmids\": [\"18615735\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"A novel DOCK4 isoform (DOCK4-Ex49) is expressed in brain, eye, and inner ear; it localizes to stereocilia hair bundles in the inner ear; it binds nucleotide-free Rac and activates Rac as effectively as DOCK2; it interacts with the PDZ-domain protein harmonin (USH1C) identified by yeast two-hybrid\",\n      \"method\": \"Yeast two-hybrid, immunostaining with isoform-specific antibody, Rac binding/activation assay\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct localization experiment with mechanistic context, biochemical Rac binding assay, but interaction validated only by Y2H\",\n      \"pmids\": [\"16464467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"DOCK4 and its splicing variant bind PIP3 through the DHR-1 domain, suggesting regulation of DOCK4 by phosphoinositides\",\n      \"method\": \"PIP3-analog bead binding assay, deletion mutant mapping\",\n      \"journal\": \"IUBMB life\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct biochemical binding assay with domain mapping, single lab, single method\",\n      \"pmids\": [\"18459162\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Dock4 is concentrated in dendritic spines and promotes spine formation via interaction with the actin-binding protein cortactin; a GEF-deficient mutant and a mutant lacking the cortactin-binding region both fail to rescue spine density upon Dock4 knockdown; cortactin knockdown suppresses Dock4-mediated spine formation\",\n      \"method\": \"shRNA knockdown and rescue with domain mutants, Co-immunoprecipitation, confocal imaging, dendritic spine density quantification\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal KD, domain-mapping rescue experiments, Co-IP, multiple orthogonal methods\",\n      \"pmids\": [\"23536706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Dock4 forms a complex with SH3YL1 (a phosphoinositide-binding protein) via the C-terminal proline-rich region of Dock4; SH3YL1 interaction promotes Dock4-mediated Rac1 activation and cell migration; phosphoinositide-binding domain mutations in SH3YL1 disrupt its ability to promote Dock4-mediated migration; SH3YL1 depletion suppresses cell migration\",\n      \"method\": \"Co-immunoprecipitation, Rac1 activation assay, domain-mapping, siRNA knockdown, cell migration assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP, functional Rac1 assay, domain mutagenesis, KD phenotype; single lab\",\n      \"pmids\": [\"24508479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TGF-β induces DOCK4 expression via the Smad pathway in lung adenocarcinoma cells; DOCK4 induction mediates TGF-β's pro-metastatic effects by enhancing tumor cell extravasation through Rac1 activation, without affecting EMT\",\n      \"method\": \"Smad pathway inhibition/activation, DOCK4 knockdown/overexpression, Rac1 activation assay, in vivo extravasation assays, cell motility/invasion assays\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pathway epistasis (TGF-β/Smad→DOCK4→Rac1), in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"25644601\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"DOCK4 knockdown in primary marrow CD34+ stem cells leads to decreased erythroid colony formation and increased apoptosis; reduced DOCK4 leads to disruption of F-actin filament network in erythroblasts via decreased RAC1 GTPase activation, leading to increased phosphorylation of the actin-stabilizing protein ADDUCIN\",\n      \"method\": \"siRNA knockdown in primary CD34+ cells, erythroid colony assay, F-actin quantification, RAC1 activation assay, ADDUCIN phosphorylation western blot, DOCK4 re-expression in MDS patient erythroblasts\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with defined cellular phenotype, RAC1 activity measurement, downstream effector phosphorylation, rescue experiment\",\n      \"pmids\": [\"26578796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"DOCK4 promotes nuclear β-catenin accumulation in GBM progenitor cells via increased GSK3β activity in a feed-forward mechanism; nuclear β-catenin then induces miR-302 expression, which represses cyclin D1 and stemness features, resulting in anti-proliferative effects; DOCK4 overexpression suppresses self-renewal and tumorigenicity of GBM stem-like cells\",\n      \"method\": \"DOCK4 overexpression, GSK3β activity assay, β-catenin nuclear fractionation, miR-302 reporter, cyclin D1 western blot, neurosphere assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple biochemical readouts, functional cellular assays; single lab\",\n      \"pmids\": [\"28925399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"SR-B1 recruits DOCK4 via an eight-amino-acid cytoplasmic domain of the receptor; DOCK4 promotes internalization of SR-B1 and LDL transcytosis across endothelial monolayers by coupling LDL binding to SR-B1 with activation of RAC1\",\n      \"method\": \"Co-immunoprecipitation, domain mapping (SR-B1 cytoplasmic tail mutants), Rac1 activation assay, LDL transcytosis assay across endothelial monolayers, SR-B1/DOCK4 colocalization in vesicles in vivo\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstituted transcytosis assay, domain mapping with mutagenesis, Rac1 activation, in vivo colocalization; replicated in multiple systems\",\n      \"pmids\": [\"31019307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Dock4 deficiency in mice reduces Rac1 activity in hippocampus, causing downregulation of global protein synthesis and diminished AMPA and NMDA receptor subunit expression; conditional Dock4 deletion in CA1 neurons attenuates excitatory synaptic transmission and decreases spine density; Rac1 replenishment in CA1 restores synaptic transmission and corrects social deficits; NMDA receptor pharmacological activation also restores social novelty preference\",\n      \"method\": \"Dock4 KO and conditional KO mice, Rac1 activation assay, electrophysiology, spine density analysis, western blot for receptor subunits, viral Rac1 rescue, pharmacological NMDA activation\",\n      \"journal\": \"Molecular psychiatry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO/conditional KO with defined synaptic phenotype, Rac1 activity measurement, rescue experiments, multiple orthogonal methods\",\n      \"pmids\": [\"31388105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Reduced DOCK4 expression in hematopoietic stem cells leads to increased tyrosine phosphorylation of LYN kinase and phosphatases SHIP1 (INPP5D) and SHP1 (PTPN6); LYN kinase targets SHIP1 and SHP1 as substrates; these signaling alterations increase migration and impede HSC differentiation; pharmacological SHP1 inhibition reverses erythroid differentiation block in DOCK4-low/-7q MDS cells\",\n      \"method\": \"Phosphoproteomics, siRNA knockdown, kinase substrate assay, migration assay, erythroid differentiation assay, pharmacological inhibition\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphoproteomics plus functional validation; single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"31308061\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Two DOCK4 variants (Exon27-52 deletion producing Dock4-945VS, and missense R853H) show decreased ability to activate both Rac1 and Rap1, are dysfunctional for cell morphology/cytoskeleton regulation, and have compromised function in promoting neurite outgrowth and dendritic spine formation; R853H partially loses ability to promote excitatory synaptic transmission while 945VS totally loses it\",\n      \"method\": \"GTPase activation assay (Rac1, Rap1), cell morphology analysis, neurite outgrowth assay in Neuro-2a cells and hippocampal neurons, spine density quantification, electrophysiological recordings\",\n      \"journal\": \"Frontiers in cellular neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct in vitro GEF assay for both Rac1 and Rap1, functional neurite/spine assays, electrophysiology; multiple orthogonal methods\",\n      \"pmids\": [\"32009906\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"DOCK4 overexpression increases cytotrophoblast (CTB) invasiveness, consistent with the placenta accreta spectrum (PAS) over-invasion phenotype; DOCK4 mRNA is the most highly upregulated molecule in PAS CTBs compared to normal depth-invading CTBs\",\n      \"method\": \"Global gene expression comparison, DOCK4 overexpression with invasion assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — overexpression with functional invasion assay; limited mechanistic dissection\",\n      \"pmids\": [\"32576693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DOCK4 deficiency in mice causes pulmonary hemorrhage, incomplete smooth muscle coverage in pulmonary vessels, increased basal microvascular permeability, and impaired S1P-induced reversal of thrombin-induced permeability; DOCK4 rapidly translocates to the cell periphery (detergent-insoluble fraction) upon S1P treatment; DOCK4 absence prevents S1P-induced Rac1 activation; DOCK4-silenced cells exhibit enhanced RhoA activation; DOCK4 maintains AJs by balancing RhoA and Rac1 activity\",\n      \"method\": \"DOCK4-deficient mice (in vivo hemorrhage, permeability), DOCK4 silencing and reconstitution in HPAEC, subcellular fractionation, Rac1/RhoA activation assays, endothelial permeability assay\",\n      \"journal\": \"Arteriosclerosis, thrombosis, and vascular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with defined vascular phenotype, KD/reconstitution in human cells, direct GTPase activity measurements, localization experiment with functional consequence\",\n      \"pmids\": [\"35477279\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Dock4 knockdown in cochlear hair cells causes hair bundle deficits, increased oxidative stress, and progressive HC apoptosis; mechanistically, Rac1/β-catenin signaling is downregulated in Dock4 KD cochleae, causing disorganized stereocilia and increased oxidative stress\",\n      \"method\": \"piggyBac transposon-mediated Dock4 KD mice, ABR/DPOAE hearing tests, hair bundle morphology, Rac1 and β-catenin western blot/immunofluorescence, oxidative stress markers, HC apoptosis assay\",\n      \"journal\": \"Fundamental research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD mouse with defined phenotype plus molecular pathway readout; single lab\",\n      \"pmids\": [\"38933554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Brain endothelial cells activate EGFR signaling in triple-negative breast cancer cells via soluble factors, and this activation occurs via DOCK4 (RAC1 GEF); DOCK4 is required for breast cancer cell extravasation to the brain in vivo; DOCK4 knockdown inhibits elongated morphology preceding intercalation into brain endothelium; DOCK4 and DOCK9 together mediate paracrine stimulation of mesenchymal-like morphology via RAC1 and CDC42\",\n      \"method\": \"DOCK4 knockdown, in vivo brain extravasation assay, cell morphology analysis, EGFR inhibitor (Afatinib) experiments, RAC1/CDC42 activation assays\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo extravasation assay plus mechanistic KD; single lab\",\n      \"pmids\": [\"38762624\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HIF2α functions in normoxia in kidney epithelial cells to induce Dock4/Rac1/Pak1 signaling, which mediates stability and compaction of E-cadherin at nascent adherens junctions; HIF2α- or Dock4-deficient cells show aberrant cyst morphogenesis in 3D cultures\",\n      \"method\": \"HIF2α and Dock4 siRNA knockdown, Rac1/Pak1 activation assays, E-cadherin localization imaging, 3D cyst morphogenesis assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis (HIF2α→Dock4→Rac1/Pak1), functional 3D assay, GTPase activation measurement; single lab\",\n      \"pmids\": [\"38802496\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Dock4 in dorsal root ganglion neurons interacts with Nav1.7 and mediates its trafficking from the membrane to the cytoplasm; Dock4 acts as an adaptor binding the motor protein Dynein to form a Dynein/DOCK4/Nav1.7 complex, where Dynein provides mechanical force for Nav1.7 trafficking; DOCK4 expression in DRG neurons is regulated by histone H4K8 lactylation; DOCK4 deficiency increases heat nociception\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation assay, Nav1.7 trafficking assay, Dock4 KD in DRG (mice and nonhuman primates), histone lactylation ChIP, nociception behavioral assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — Co-IP of ternary complex, functional trafficking assay, in vivo KD in two species, epigenetic regulation mapping; multiple orthogonal methods\",\n      \"pmids\": [\"40759894\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Heterozygous loss-of-function missense variants in DOCK4 impair neurite outgrowth in Neuro-2A cells; Dock4 knockout Neuro-2A cells also exhibit defects in neurite outgrowth; molecular modeling suggests missense variants affect the globular structure of DOCK4\",\n      \"method\": \"In vitro functional expression of DOCK4 variants in Neuro-2A cells (neurite outgrowth assay), Dock4 KO cells, molecular modeling\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct functional assay in KO and mutant overexpression; single lab\",\n      \"pmids\": [\"38526744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"THEMIS2 acts as a molecular scaffold that recruits TBK1 to DOCK4, facilitating phosphorylation of DOCK4 at serine 1787 (S1787); this post-translational modification enables DOCK4 to engage with CRKII, subsequently triggering Rap1 signaling activation and promoting ovarian cancer metastasis\",\n      \"method\": \"Immunoprecipitation-mass spectrometry, GST pull-down assay for active Rap1 (Rap1-GTP), co-immunoprecipitation, phospho-site mapping, wound healing and invasion assays, in vivo metastasis model\",\n      \"journal\": \"Cellular oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — IP-MS interaction identification, biochemical Rap1 activation assay, phospho-site identification, functional rescue; single lab\",\n      \"pmids\": [\"40227532\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Dock4 facilitates excitatory synaptic transmission in spinal dorsal horn neurons by promoting GluN2B expression at the synaptic site and synaptogenesis; Dock4 knockdown prevents dendritic growth, synaptogenesis, and increased excitatory postsynaptic currents in a spinal nerve ligation neuropathic pain model\",\n      \"method\": \"Dock4 RNAi knockdown, whole-cell patch clamp electrophysiology in spinal cord slices, GluN2B immunofluorescence/western blot, Rac1 activation assay, dendritic spine analysis in cultured dorsal spinal neurons\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with electrophysiology and spine morphology readouts; single lab\",\n      \"pmids\": [\"39282658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP36 directly binds DOCK4 and mediates its deubiquitination, thereby stabilizing DOCK4; stabilized DOCK4 activates Wnt/β-catenin signaling and promotes EMT in diabetic renal tubular epithelial cells\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, USP36 overexpression/knockdown with DOCK4 stability readout, EMT marker western blot\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and deubiquitination assay; single lab, limited mechanistic dissection downstream\",\n      \"pmids\": [\"33968925\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DOCK4 is an unconventional guanine nucleotide exchange factor (GEF) that activates Rac1 and Rap1 GTPases through its DHR-2 domain (regulated by PIP3 binding at DHR-1, by RhoG/ELMO upstream inputs, by GSK3β phosphorylation, and by TBK1-mediated phosphorylation at S1787); it functions as a scaffold in multiple signaling pathways including Wnt/β-catenin (by interacting with the APC/Axin/GSK3β degradation complex), TGF-β/Smad-driven metastasis, and SR-B1-mediated LDL transcytosis; in neurons it localizes to dendritic spines where it promotes spine formation and excitatory synaptic transmission via Rac1 activation and cortactin interaction, and it forms a Dynein/DOCK4/Nav1.7 complex in DRG neurons to regulate Nav1.7 membrane trafficking and heat nociception; in endothelial cells it maintains adherens junction integrity by balancing Rac1 and RhoA activities; and its loss in hematopoietic progenitors impairs erythropoiesis through reduced RAC1 activity, disrupted F-actin, and increased ADDUCIN phosphorylation, with downstream LYN/SHP1/SHIP1 signaling perturbation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"DOCK4 is an atypical guanine nucleotide exchange factor (GEF) that activates Rac1 and Rap1 GTPases to regulate cytoskeletal dynamics, cell adhesion, and migration across diverse tissues. Its DHR-2 domain catalyzes nucleotide exchange on Rac1 and Rap1, while the DHR-1 domain binds PIP3 for membrane targeting; upstream activation is mediated by RhoG/ELMO-dependent translocation to the plasma membrane, GSK3β phosphorylation in the Wnt/β-catenin pathway, and TBK1-mediated phosphorylation at S1787 that enables CRKII engagement and Rap1 signaling [PMID:12628187, PMID:17027967, PMID:18459162, PMID:18641688, PMID:40227532]. In neurons, DOCK4 localizes to dendritic spines where it promotes spine formation and excitatory synaptic transmission through Rac1-dependent cortactin interaction and regulation of NMDA/AMPA receptor subunit expression; it also functions as a scaffold forming a Dynein/DOCK4/Nav1.7 complex in DRG neurons to control Nav1.7 membrane trafficking and heat nociception [PMID:23536706, PMID:31388105, PMID:40759894]. Beyond the nervous system, DOCK4 maintains endothelial adherens junction integrity by balancing Rac1 and RhoA activities, couples SR-B1 to LDL transcytosis via Rac1 activation in endothelial cells, supports erythropoiesis through RAC1-dependent F-actin organization, and mediates TGF-β/Smad-driven tumor cell extravasation [PMID:35477279, PMID:31019307, PMID:26578796, PMID:25644601].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing DOCK4 as a GEF for Rap1 that promotes adherens junctions and functions as a tumor suppressor resolved its basic enzymatic identity and linked it to cell adhesion and cancer.\",\n      \"evidence\": \"GTPase activation assays, C. elegans ced-5 rescue, and soft agar/invasion assays with cancer-associated mutant in human cell lines\",\n      \"pmids\": [\"12628187\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Rac1 GEF activity not yet demonstrated\", \"structural basis for Rap1 specificity unknown\", \"in vivo tumor suppressor role not validated in mammalian models\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identifying RhoG/ELMO as upstream activators that translocate DOCK4 to the membrane for Rac1 activation established DOCK4 as a dual Rac1/Rap1 GEF regulated by a GTPase cascade, answering how its membrane recruitment and activation are controlled.\",\n      \"evidence\": \"Co-immunoprecipitation, subcellular fractionation, Rac1-GTP pulldown, and siRNA knockdown with migration assay in NIH3T3 cells; parallel identification of a brain-specific isoform binding Rac and harmonin\",\n      \"pmids\": [\"17027967\", \"16464467\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"ELMO isoform specificity not resolved\", \"harmonin interaction confirmed only by Y2H\", \"structural basis of RhoG-ELMO-DOCK4 complex unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that DOCK4 integrates into the Wnt/β-catenin destruction complex (APC/Axin/GSK3β) and is phosphorylated by GSK3β to enhance Rac activation revealed a non-canonical role as a scaffold linking Wnt signaling to cytoskeletal remodeling, while PIP3 binding via DHR-1 established a lipid-dependent regulatory mechanism.\",\n      \"evidence\": \"Co-IP of DOCK4 with APC/Axin/GSK3β, in vitro kinase assay, TCF reporter in zebrafish; PIP3-analog bead binding with deletion mapping; neurite outgrowth assays in hippocampal neurons with ELMO2/CrkII complex\",\n      \"pmids\": [\"18641688\", \"18459162\", \"18615735\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphorylation site on DOCK4 by GSK3β not mapped\", \"relative contribution of PIP3 vs. ELMO to membrane targeting unclear\", \"in vivo Wnt phenotype not tested in mammalian models at this stage\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showing that DOCK4 concentrates in dendritic spines and requires both GEF activity and cortactin binding to promote spine formation established the molecular mechanism by which DOCK4 controls synaptic structure.\",\n      \"evidence\": \"shRNA knockdown and rescue with GEF-dead and cortactin-binding-deficient mutants, Co-IP, confocal spine density quantification in hippocampal neurons\",\n      \"pmids\": [\"23536706\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether cortactin interaction is direct or bridged unknown\", \"electrophysiological consequences not assessed\", \"upstream signals activating DOCK4 at spines not identified\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying DOCK4 as a TGF-β/Smad transcriptional target that drives tumor extravasation via Rac1, and demonstrating its requirement for erythropoiesis via RAC1-dependent actin organization, expanded DOCK4 function beyond neurons to cancer metastasis and hematopoiesis.\",\n      \"evidence\": \"Smad pathway epistasis and in vivo extravasation assays in lung adenocarcinoma; siRNA in CD34+ cells with erythroid colony assay, F-actin/ADDUCIN phosphorylation readouts, and rescue in MDS erythroblasts\",\n      \"pmids\": [\"25644601\", \"26578796\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct transcriptional regulation by Smad not confirmed by ChIP\", \"specific DOCK4 domains required for erythroid function not mapped\", \"relationship between Rap1 vs. Rac1 activation in erythropoiesis unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Discovering that SR-B1 recruits DOCK4 via its cytoplasmic tail to drive LDL transcytosis through Rac1 activation revealed a receptor-coupled GEF mechanism in endothelial lipid transport, while conditional Dock4 KO in hippocampal CA1 neurons established that DOCK4 controls global protein synthesis, glutamate receptor expression, and social behavior via Rac1.\",\n      \"evidence\": \"Co-IP with SR-B1 tail mutants, LDL transcytosis assay, in vivo colocalization; Dock4 conditional KO mice with electrophysiology, spine analysis, Rac1 viral rescue, NMDA pharmacological rescue; phosphoproteomics in hematopoietic cells showing LYN/SHP1/SHIP1 perturbation\",\n      \"pmids\": [\"31019307\", \"31388105\", \"31308061\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether DOCK4 GEF activity is required for SR-B1 coupling not tested with GEF-dead mutant\", \"how DOCK4 controls global translation machinery not resolved\", \"LYN/SHP1 pathway connection to Rac1 unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrating that DOCK4 maintains endothelial barrier integrity by balancing Rac1 and RhoA upon S1P stimulation, with DOCK4-deficient mice exhibiting pulmonary hemorrhage, established its vascular homeostatic function and the RhoA-counterbalancing mechanism.\",\n      \"evidence\": \"DOCK4-deficient mice with hemorrhage/permeability phenotypes, DOCK4 silencing and reconstitution in HPAEC, Rac1/RhoA activation assays, subcellular fractionation upon S1P treatment\",\n      \"pmids\": [\"35477279\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether DOCK4 directly inhibits RhoA or acts indirectly via Rac1 not resolved\", \"S1P receptor isoform specificity for DOCK4 recruitment unknown\", \"role in other vascular beds not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identifying DOCK4 as a scaffold in a Dynein/DOCK4/Nav1.7 ternary complex that mediates Nav1.7 membrane trafficking in DRG neurons, regulated by histone H4K8 lactylation, revealed a GEF-independent adaptor function and an epigenetic control layer for DOCK4 expression in pain signaling.\",\n      \"evidence\": \"Co-IP and proximity ligation assay for ternary complex, Nav1.7 trafficking assay, Dock4 KD in mice and nonhuman primates, histone lactylation ChIP, nociception behavioral assays\",\n      \"pmids\": [\"40759894\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether GEF activity contributes to Nav1.7 trafficking not tested\", \"lactylation writers/erasers controlling DOCK4 locus not identified\", \"applicability to other ion channels unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealing that TBK1 phosphorylates DOCK4 at S1787 (scaffolded by THEMIS2) to enable CRKII engagement and Rap1 activation in ovarian cancer metastasis provided the first mapped phospho-regulatory switch controlling DOCK4's Rap1 GEF output.\",\n      \"evidence\": \"IP-mass spectrometry, phospho-site mapping, GST-Rap1 pulldown, Co-IP, in vivo metastasis model\",\n      \"pmids\": [\"40227532\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether S1787 phosphorylation also regulates Rac1 activation unknown\", \"structural basis for phospho-dependent CRKII binding not resolved\", \"single lab finding awaiting independent replication\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis for DOCK4's dual Rac1/Rap1 specificity, the relative contributions of GEF-dependent versus GEF-independent (scaffolding) functions across tissues, and how tissue-specific isoforms and post-translational modifications partition DOCK4 among its diverse signaling outputs.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No crystal or cryo-EM structure of DOCK4 DHR-2 with Rac1 or Rap1\", \"GEF-independent adaptor functions not systematically separated from GEF activity\", \"isoform-specific functions in inner ear and brain not fully delineated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 8, 9, 11, 14, 16, 22]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [20, 22]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 11, 16]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [6, 9]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2, 8, 11, 16, 19, 22]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [0, 16, 19]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [3, 6, 12, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [8, 18, 22]}\n    ],\n    \"complexes\": [\n      \"DOCK4/ELMO/CrkII\",\n      \"Dynein/DOCK4/Nav1.7\",\n      \"APC/Axin/GSK3β destruction complex\"\n    ],\n    \"partners\": [\n      \"ELMO2\",\n      \"CRKII\",\n      \"SCARB1\",\n      \"CORT\",\n      \"SH3YL1\",\n      \"THEMIS2\",\n      \"TBK1\",\n      \"USP36\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}