{"gene":"ARHGEF3","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2002,"finding":"XPLN (ARHGEF3) is a guanine nucleotide exchange factor that stimulates GDP-to-GTP exchange on RhoA and RhoB but not RhoC, RhoG, Rac1, or Cdc42 in vitro, and the selectivity against RhoC is determined by isoleucine 43 in RhoC (valine in RhoA/RhoB). XPLN preferentially associates with RhoA and RhoB, and when expressed in cells stimulates stress fiber and focal adhesion assembly in a Rho kinase-dependent manner.","method":"In vitro nucleotide exchange assay, co-precipitation/binding assay, cell overexpression with dominant-negative Rho kinase and active RhoA mutants, focus formation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of GEF activity with mutagenesis identifying the discriminating residue (Ile43), combined with cell-based epistasis and binding assays in one rigorous study","pmids":["12221096"],"is_preprint":false},{"year":2012,"finding":"Crystal structure of the tandem DH-PH domains of mouse XPLN (ARHGEF3) was determined at 1.79 Å resolution by multiwavelength anomalous dispersion. The structure revealed an α4-α5 loop in the DH domain that is flexible and intramolecular DH-PH interactions, suggesting PH-domain rearrangement occurs upon RhoA binding. High structural similarity to other RhoGEFs (NET1, PDZ-RhoGEF, LARG, ITSN1/2) was observed.","method":"X-ray crystallography (MAD phasing, 1.79 Å resolution)","journal":"Acta crystallographica. Section F, Structural biology and crystallization communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure at high resolution with functional interpretation; single study but direct structural determination","pmids":["23192023"],"is_preprint":false},{"year":2013,"finding":"XPLN (ARHGEF3) interacts with mTORC2 (but not mTORC1) in a rictor-dependent manner and acts as an endogenous inhibitor of mTORC2 kinase activity toward Akt. Knockdown of XPLN enhances Akt Ser473 phosphorylation; overexpression suppresses it. Purified XPLN inhibits mTORC2 kinase activity in vitro without affecting mTORC1. The GEF activity of XPLN is dispensable for mTORC2 inhibition, whereas the N-terminal 125-amino-acid fragment is necessary and sufficient for mTORC2 inhibition and for negative regulation of myoblast differentiation.","method":"Yeast two-hybrid screen, co-immunoprecipitation, siRNA knockdown, overexpression, in vitro mTORC2 kinase assay with purified components, domain deletion analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro reconstituted kinase inhibition with purified XPLN, complemented by reciprocal Co-IP, domain mapping, and genetic rescue experiments, all in one study","pmids":["24043828"],"is_preprint":false},{"year":2015,"finding":"In AML cells (U937), ARHGEF3 protein is primarily nuclear but undergoes cytoplasmic translocation upon HDACi (MS275) treatment. Cytoplasmic ARHGEF3 activates the RhoA/ROCK pathway, leading to SAPK/JNK phosphorylation and Elk1 activation. ARHGEF3 silencing prevents RhoA activation, reduces SAPK/JNK phosphorylation and Elk1 activity, and blocks CD68 macrophage differentiation marker expression.","method":"siRNA knockdown, immunofluorescence/subcellular fractionation for localization, Rho activation assay (GTP-RhoA pulldown), western blotting for pathway components, pharmacological inhibitors (C3 transferase, Y27632)","journal":"Epigenetics","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — localization tied to functional consequence, RhoA activation measured directly, multiple inhibitor validations; single lab","pmids":["25494542"],"is_preprint":false},{"year":2011,"finding":"Silencing of arhgef3 in zebrafish causes microcytic hypochromic anemia rescued by intracellular iron supplementation, demonstrating that ARHGEF3 regulates transferrin/iron uptake in erythroid cells. Silencing of RhoA phenocopies arhgef3 loss. In K562 cells, ARHGEF3 knockdown severely impairs transferrin uptake, placing ARHGEF3 upstream of RhoA in an iron-uptake pathway.","method":"Morpholino knockdown in zebrafish, rescue by iron injection, siRNA knockdown in K562 cells, transferrin uptake assay","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (arhgef3/RhoA knockdown + rescue), direct functional assay (transferrin uptake); single lab, two model systems","pmids":["21715309"],"is_preprint":false},{"year":2021,"finding":"ARHGEF3 KO mice show enhanced skeletal muscle mass, fiber size, and function after acute injury. This effect requires the GEF activity of ARHGEF3 (not Akt signaling) and operates via the RhoA/ROCK pathway. ARHGEF3 KO promotes autophagy, and autophagy activation is required for the enhanced regeneration phenotype. Overexpression of ARHGEF3 inhibits muscle regeneration in a ROCK-dependent manner. In aged mice, ARHGEF3 depletion prevents muscle weakness by restoring autophagy.","method":"Knockout mouse model (ARHGEF3-KO), acute muscle injury model, GEF-inactive mutant overexpression, ROCK inhibitor treatment, autophagy flux assays, muscle function measurements","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO with multiple orthogonal phenotypic readouts, GEF-inactive mutant distinguishing GEF vs non-GEF functions, pharmacological epistasis with ROCK inhibitor; replicated across age groups","pmids":["33406419"],"is_preprint":false},{"year":2017,"finding":"XPLN (ARHGEF3) knockdown in human lung fibroblasts stimulates SPARC expression and Akt Ser473 phosphorylation. TGF-β1 downregulates XPLN via Smad2/3. HDACi treatment upregulates XPLN mRNA and reverses TGF-β1-induced SPARC expression, establishing XPLN as a negative regulator of the mTORC2-SPARC axis.","method":"siRNA knockdown, western blotting and qRT-PCR for SPARC and pAkt, TGF-β1/Smad pathway analysis, HDAC inhibitor treatment","journal":"Pulmonary pharmacology & therapeutics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single lab, multiple validated readouts but no in vitro reconstitution; mechanism consistent with established mTORC2 role","pmids":["28315487"],"is_preprint":false},{"year":2014,"finding":"ARHGEF3 knockdown in osteoblast-like cells causes downregulation of TNFRSF11B (osteoprotegerin). RHOA knockdown in osteoblast-like cells downregulates ACTA2 (alpha-2 actin) and upregulates PTH1R, and in osteoclast-like cells downregulates ARHGDIA and ACTA2, placing ARHGEF3/RhoA upstream of these bone-cell gene-expression programs.","method":"siRNA knockdown, microarray followed by qRT-PCR validation in multiple human osteoblast-like and osteoclast-like cell lines","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — knockdown with transcriptional readout validated by qRT-PCR; multiple cell lines; no direct enzymatic or binding assay","pmids":["24840563"],"is_preprint":false},{"year":2022,"finding":"ARHGEF3 overexpression inhibits HCV subgenomic replicon RNA replication and full-length HCV replication, as well as replication of yellow fever virus and Zika virus (Flaviviridae), in cell-based systems. This antiviral activity is conserved between human and rhesus macaque ARHGEF3.","method":"Lentiviral overexpression screen with luciferase-expressing HCV replicons, independent validation with full-length HCV infection assay and flavivirus replication assays","journal":"Viruses","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — cell-based overexpression validated in multiple viral systems; mechanism of antiviral action not defined at molecular level","pmids":["36016278"],"is_preprint":false},{"year":2022,"finding":"ARHGEF3 promotes NSCLC cell proliferation in vitro and in vivo by stabilizing ATP-citrate lyase (ACLY) protein: ARHGEF3 reduces acetylation of ACLY on Lys17 and Lys86, preventing ACLY interaction with its E3 ubiquitin ligase NEDD4 and subsequent degradation. This function is independent of ARHGEF3's GEF activity.","method":"siRNA knockdown and overexpression, xenograft model, co-immunoprecipitation (ACLY-NEDD4 interaction), acetylation site mapping, GEF-inactive mutant","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP demonstrating ACLY-NEDD4 dissociation, acetylation site identification, GEF-inactive mutant distinguishing mechanism; single lab","pmids":["36241648"],"is_preprint":false},{"year":2023,"finding":"ARHGEF3 is elevated in dystrophic mdx muscles and drives RhoA/ROCK activation. ARHGEF3 KO in mdx mice restores muscle quality (force production) and morphology without affecting regeneration. ARHGEF3 overexpression further compromises mdx muscle quality in a GEF activity- and ROCK-dependent manner. The ARHGEF3/ROCK pathway impairs muscle function by blocking autophagy flux, as chloroquine-mediated autophagy inhibition abolishes the benefit of ARHGEF3/ROCK inhibition.","method":"Arhgef3 KO in mdx mice, 3D-engineered mdx muscle model, ROCK inhibitor (Y-27632), GEF-inactive mutant overexpression, autophagy flux assay with chloroquine, muscle force measurements","journal":"Journal of cachexia, sarcopenia and muscle","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO + pharmacological and genetic rescue in two muscle models, GEF-inactive mutant, autophagy epistasis; orthogonal to companion paper (PMID:33406419)","pmids":["37311604"],"is_preprint":false},{"year":2025,"finding":"ARHGEF3 promotes adipocyte hypertrophy and differentiation through two coordinated mechanisms: (1) RhoA-dependent facilitation of YAP nuclear translocation and YAP binding to the RhoA promoter, and (2) enhancement of PPARγ transcriptional activity, establishing a reciprocal activation loop. ARHGEF3-deficient mice on a high-fat diet show reduced weight gain and smaller adipocyte size correlated with decreased RhoA expression and altered cytoskeletal dynamics.","method":"ARHGEF3-KO mice on HFD, in vitro adipogenesis (C3H10T1/2 cells), ChIP for YAP-RhoA promoter binding, co-immunoprecipitation, luciferase reporter for PPARγ activity, immunostaining for YAP localization","journal":"Journal of advanced research","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — ChIP, Co-IP, reporter assay, and KO mouse; single lab; YAP-RhoA promoter binding is novel but needs independent replication","pmids":["40216078"],"is_preprint":false},{"year":2026,"finding":"Tumor-intrinsic ARHGEF3 activates the RHOA-ROCK-PTEN cascade to inhibit AKT signaling, which upregulates IRF1-dependent chemokines CXCL10 and CXCL11 (promoting T-cell infiltration) and suppresses FASN-mediated fatty acid synthesis (limiting myeloid immunosuppression). These dual effects reshape the tumor microenvironment toward T-cell inflammation.","method":"Cell-based gain/loss-of-function, RhoA activity assay, pathway inhibitors, CXCL10/11 measurement, FASN activity assay, in vivo tumor models","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple pathway readouts with genetic and pharmacological epistasis; single lab, novel pathway; not yet independently replicated","pmids":["42023986"],"is_preprint":false},{"year":2026,"finding":"ARHGEF3 restricts placode cell fate acquisition and establishes a radial gradient of P-cadherin (but not E-cadherin) across hair follicle placodes during embryonic development. In Arhgef3-KO embryos, placodes are enlarged with elevated P-cadherin at junctions and disrupted gradient, correlating with aberrant epithelial organization and altered hair follicle downgrowth geometry.","method":"Arhgef3 KO mouse embryos, immunostaining for P-cadherin and E-cadherin, hair follicle morphometry, cell culture models for F-actin accumulation","journal":"PLoS biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with specific cadherin patterning phenotype, distinguishing P- vs E-cadherin; single lab, peer-reviewed","pmids":["41490244"],"is_preprint":false},{"year":2024,"finding":"miR-451a directly binds the 3'-UTR of ARHGEF3 mRNA (confirmed by dual-luciferase reporter assay), and knockdown of ARHGEF3 in K562 cells reverses hydroquinone-induced suppression of erythroid differentiation, placing ARHGEF3 as a downstream effector of the miR-451a/c-Jun axis in erythroid maturation.","method":"Dual-luciferase 3'-UTR reporter assay, siRNA knockdown, erythroid differentiation assays in K562 cells","journal":"Toxicology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct 3'-UTR validation combined with functional knockdown; consistent with prior erythroid role (PMID:21715309); single lab","pmids":["38801936"],"is_preprint":false},{"year":2025,"finding":"Inhibition of miR-512-3p in Moyamoya disease endothelial colony-forming cells increases ARHGEF3 expression and downstream RhoA GTPase activity, leading to enhanced tubule formation (angiogenesis rescue). Bioinformatics and functional data identify ARHGEF3 as a direct target of miR-512-3p.","method":"miR-512-3p inhibition in primary ECFCs, GTPase activity assay, tubule formation assay, western blotting for ARHGEF3/RhoA","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, no 3'-UTR reporter validation for ARHGEF3 targeting reported; functional link is indirect","pmids":["40634490"],"is_preprint":false},{"year":2024,"finding":"ARHGEF3 promotes F-actin accumulation at the cell cortex and P-cadherin enrichment at cell-cell junctions in culture models, consistent with its role in hair placode morphogenesis.","method":"Cell culture overexpression, phalloidin staining for F-actin, immunostaining for P-cadherin","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single overexpression experiment; findings later incorporated into peer-reviewed version (PMID:41490244)","pmids":["39314354"],"is_preprint":true}],"current_model":"ARHGEF3 (XPLN) is a DH-PH domain-containing guanine nucleotide exchange factor that selectively activates RhoA and RhoB (but not RhoC, owing to Ile43 in RhoC) to drive actin cytoskeletal remodeling, stress fiber formation, and diverse downstream programs including autophagy regulation in skeletal muscle, transferrin/iron uptake in erythroid cells, and P-cadherin patterning in hair follicle morphogenesis; independently of its GEF activity, ARHGEF3 also binds mTORC2 via rictor and inhibits mTORC2 kinase activity toward Akt through its N-terminal 125-amino-acid domain, and stabilizes ACLY protein by reducing its acetylation, making ARHGEF3 a bifunctional regulator with both canonical Rho-GEF and non-canonical mTORC2/protein-stability functions."},"narrative":{"mechanistic_narrative":"ARHGEF3 (XPLN) is a DH-PH domain guanine nucleotide exchange factor that selectively activates RhoA and RhoB to drive actin cytoskeletal remodeling, stress fiber and focal adhesion assembly through Rho kinase, while also executing GEF-independent regulatory functions [PMID:12221096, PMID:23192023]. Its enzymatic specificity is intrinsic: ARHGEF3 catalyzes GDP-to-GTP exchange on RhoA and RhoB but not RhoC, a discrimination set by isoleucine 43 of RhoC, and its tandem DH-PH module undergoes PH-domain rearrangement upon RhoA engagement [PMID:12221096, PMID:23192023]. Through this RhoA/ROCK axis ARHGEF3 governs diverse programs in vivo: it restrains skeletal muscle mass, fiber size, and regeneration by blocking autophagy flux, an activity that requires GEF function and is recapitulated in dystrophic mdx muscle [PMID:33406419, PMID:37311604]; it supports erythroid transferrin/iron uptake upstream of RhoA [PMID:21715309]; and it shapes P-cadherin gradients and placode cell fate during hair follicle morphogenesis [PMID:41490244]. ARHGEF3 carries a separable, GEF-independent activity through its N-terminal 125-amino-acid domain that binds mTORC2 via rictor and inhibits its kinase activity toward Akt Ser473, thereby negatively regulating myoblast differentiation and the mTORC2-SPARC axis [PMID:24043828, PMID:28315487]. In a further non-canonical role, ARHGEF3 stabilizes ATP-citrate lyase by reducing its acetylation and blocking NEDD4-mediated degradation to promote tumor cell proliferation [PMID:36241648]. Additional context-specific roles in AML macrophage differentiation, adipocyte hypertrophy, antiviral restriction, and tumor microenvironment remodeling have been described [PMID:25494542, PMID:40216078, PMID:36016278, PMID:42023986].","teleology":[{"year":2002,"claim":"Establishing whether ARHGEF3 is a functional GEF and which Rho GTPases it acts on defined its core biochemical identity and the structural basis of its selectivity.","evidence":"In vitro nucleotide exchange and binding assays with mutagenesis (Ile43), plus cell overexpression with dominant-negative Rho kinase","pmids":["12221096"],"confidence":"High","gaps":["Did not establish physiological contexts where RhoA vs RhoB activation matters","Did not address GEF-independent functions"]},{"year":2011,"claim":"Linking ARHGEF3 to erythroid iron handling showed that its Rho-GEF activity has a tissue-specific physiological output beyond cytoskeletal assembly.","evidence":"Morpholino knockdown in zebrafish with iron rescue, siRNA and transferrin uptake assay in K562 cells","pmids":["21715309"],"confidence":"Medium","gaps":["Molecular link between RhoA activity and transferrin uptake machinery undefined","Single lab across two model systems"]},{"year":2012,"claim":"Solving the tandem DH-PH structure provided the structural rationale for substrate engagement and conformational change upon RhoA binding.","evidence":"X-ray crystallography at 1.79 Å by MAD phasing","pmids":["23192023"],"confidence":"High","gaps":["No co-crystal with RhoA/RhoB to confirm the inferred PH rearrangement","N-terminal mTORC2-binding region not in the construct"]},{"year":2013,"claim":"Discovery that ARHGEF3 binds and inhibits mTORC2 independently of its GEF activity revealed it as a bifunctional protein with a separable N-terminal regulatory module.","evidence":"Yeast two-hybrid, reciprocal Co-IP, in vitro mTORC2 kinase assay with purified XPLN, and domain deletion mapping to N-terminal 125 aa","pmids":["24043828"],"confidence":"High","gaps":["Structural basis of rictor/mTORC2 binding unresolved","How GEF and mTORC2-inhibitory activities are coordinated unknown"]},{"year":2014,"claim":"Knockdown transcriptomics placed ARHGEF3/RhoA upstream of bone-cell gene-expression programs, extending its reach to transcriptional outputs.","evidence":"siRNA knockdown with microarray and qRT-PCR validation in osteoblast- and osteoclast-like lines","pmids":["24840563"],"confidence":"Medium","gaps":["No direct enzymatic or binding assay connecting ARHGEF3 to the transcriptional changes","Mechanism of gene regulation unmapped"]},{"year":2015,"claim":"Showing nuclear-to-cytoplasmic relocation upon HDAC inhibition coupled ARHGEF3 localization to RhoA/ROCK-driven myeloid differentiation, indicating regulated subcellular activity.","evidence":"siRNA, fractionation/immunofluorescence, GTP-RhoA pulldown, and pharmacological inhibitors in U937 AML cells","pmids":["25494542"],"confidence":"Medium","gaps":["Mechanism of nuclear retention and HDACi-triggered export unknown","Single cell line"]},{"year":2017,"claim":"Demonstrating that ARHGEF3 negatively regulates the mTORC2-SPARC axis and is itself suppressed by TGF-β1/Smad reinforced its mTORC2-inhibitory role and revealed an upstream control input.","evidence":"siRNA knockdown, western blot/qRT-PCR for SPARC and pAkt, TGF-β1/Smad and HDACi treatments in lung fibroblasts","pmids":["28315487"],"confidence":"Medium","gaps":["No in vitro reconstitution of the SPARC link","Single lab"]},{"year":2021,"claim":"An ARHGEF3 KO mouse demonstrated that its GEF activity restrains skeletal muscle regeneration by blocking autophagy, separating the GEF function from Akt signaling in vivo.","evidence":"KO mouse, acute injury model, GEF-inactive mutant, ROCK inhibitor, and autophagy flux assays across ages","pmids":["33406419"],"confidence":"High","gaps":["How RhoA/ROCK suppresses autophagy mechanistically not defined","Relevant muscle cell type for the effect not fully resolved"]},{"year":2022,"claim":"Identification of ACLY stabilization showed a second GEF-independent function in which ARHGEF3 controls protein stability via acetylation.","evidence":"siRNA/overexpression, xenografts, ACLY-NEDD4 Co-IP, acetylation site mapping (K17/K86), and GEF-inactive mutant in NSCLC","pmids":["36241648"],"confidence":"Medium","gaps":["How ARHGEF3 reduces ACLY acetylation enzymatically unknown","Whether ARHGEF3 acts directly on ACLY or via an intermediary unresolved"]},{"year":2022,"claim":"An overexpression screen revealed antiviral restriction against Flaviviridae, expanding ARHGEF3's functional repertoire to host defense.","evidence":"Lentiviral overexpression with HCV replicons and full-length HCV, plus YFV/ZIKV replication assays; conserved in rhesus ARHGEF3","pmids":["36016278"],"confidence":"Medium","gaps":["Molecular mechanism of antiviral action undefined","Whether GEF activity is required not tested"]},{"year":2023,"claim":"Genetic and pharmacological dissection in mdx muscle confirmed that the ARHGEF3/ROCK pathway impairs muscle quality by blocking autophagy flux, validating the autophagy mechanism in a disease setting.","evidence":"Arhgef3 KO in mdx mice, 3D-engineered muscle, ROCK inhibitor, GEF-inactive mutant, chloroquine autophagy epistasis, force measurements","pmids":["37311604"],"confidence":"High","gaps":["Upstream signals elevating ARHGEF3 in dystrophic muscle unknown","Molecular link from ROCK to autophagy machinery not detailed"]},{"year":2024,"claim":"miR-451a was shown to directly target the ARHGEF3 3'-UTR, identifying a post-transcriptional control point governing its erythroid role.","evidence":"Dual-luciferase 3'-UTR reporter, siRNA knockdown, and erythroid differentiation assays in K562 cells","pmids":["38801936"],"confidence":"Medium","gaps":["Downstream effector mechanism in erythroid maturation not defined","Single lab"]},{"year":2025,"claim":"ARHGEF3 was placed in an adipogenic loop coupling RhoA-dependent YAP nuclear translocation with PPARγ activity, linking it to metabolic tissue expansion.","evidence":"KO mice on HFD, in vitro adipogenesis, ChIP for YAP-RhoA promoter binding, Co-IP, PPARγ luciferase reporter, YAP immunostaining","pmids":["40216078"],"confidence":"Medium","gaps":["YAP-RhoA promoter binding needs independent replication","Direct molecular partner connecting ARHGEF3 to YAP unclear"]},{"year":2026,"claim":"A RHOA-ROCK-PTEN-AKT cascade was shown to remodel the tumor microenvironment via IRF1-driven chemokines and FASN suppression, connecting ARHGEF3 GEF signaling to anti-tumor immunity.","evidence":"Gain/loss-of-function, RhoA activity assay, pathway inhibitors, CXCL10/11 and FASN readouts, in vivo tumor models","pmids":["42023986"],"confidence":"Medium","gaps":["Single lab, novel pathway not independently replicated","Mechanistic link from ROCK to PTEN not detailed"]},{"year":2026,"claim":"A KO embryo study established that ARHGEF3 patterns P-cadherin gradients and restricts placode fate, demonstrating a developmental morphogenesis role tied to cytoskeletal control.","evidence":"Arhgef3 KO mouse embryos, P-/E-cadherin immunostaining, hair follicle morphometry, F-actin culture models","pmids":["41490244"],"confidence":"Medium","gaps":["How ARHGEF3 selectively controls P- but not E-cadherin unknown","Link between RhoA activity and cadherin gradient unmapped"]},{"year":null,"claim":"It remains unresolved how ARHGEF3's GEF-dependent (RhoA/RhoB/ROCK) and GEF-independent (mTORC2 inhibition, ACLY stabilization) activities are integrated, regulated, and partitioned across the diverse tissue contexts in which it acts.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model coordinating the two functional modes","No structure of full-length ARHGEF3 with its N-terminal mTORC2-binding region","Tissue-specific regulation of ARHGEF3 expression and localization incompletely defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,9]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,16]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[3]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,16]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,5,12]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5,10]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[13]}],"complexes":[],"partners":["RHOA","RHOB","RICTOR","ACLY"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NR81","full_name":"Rho guanine nucleotide exchange factor 3","aliases":["Exchange factor found in platelets and leukemic and neuronal tissues","XPLN"],"length_aa":526,"mass_kda":59.8,"function":"Acts as a guanine nucleotide exchange factor (GEF) for RhoA and RhoB GTPases","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q9NR81/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ARHGEF3","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ARHGEF3","total_profiled":1310},"omim":[{"mim_id":"612574","title":"MEAN PLATELET VOLUME/COUNT QUANTITATIVE TRAIT LOCUS 2; MPVCQTL2","url":"https://www.omim.org/entry/612574"},{"mim_id":"612115","title":"RHO GUANINE NUCLEOTIDE EXCHANGE FACTOR 3; ARHGEF3","url":"https://www.omim.org/entry/612115"},{"mim_id":"605216","title":"RHO GUANINE NUCLEOTIDE EXCHANGE FACTOR 4; ARHGEF4","url":"https://www.omim.org/entry/605216"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ARHGEF3"},"hgnc":{"alias_symbol":["STA3","XPLN","GEF3","DKFZP434F2429"],"prev_symbol":[]},"alphafold":{"accession":"Q9NR81","domains":[{"cath_id":"1.20.900.10","chopping":"103-314","consensus_level":"high","plddt":92.6972,"start":103,"end":314},{"cath_id":"2.30.29.30","chopping":"317-396_409-456","consensus_level":"high","plddt":92.0366,"start":317,"end":456}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NR81","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NR81-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NR81-F1-predicted_aligned_error_v6.png","plddt_mean":74.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ARHGEF3","jax_strain_url":"https://www.jax.org/strain/search?query=ARHGEF3"},"sequence":{"accession":"Q9NR81","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NR81.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NR81/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NR81"}},"corpus_meta":[{"pmid":"12221096","id":"PMC_12221096","title":"XPLN, a guanine nucleotide exchange factor for RhoA and RhoB, but not RhoC.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12221096","citation_count":119,"is_preprint":false},{"pmid":"24043828","id":"PMC_24043828","title":"XPLN is an endogenous inhibitor of mTORC2.","date":"2013","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/24043828","citation_count":40,"is_preprint":false},{"pmid":"33406419","id":"PMC_33406419","title":"ARHGEF3 Regulates Skeletal Muscle Regeneration and Strength through Autophagy.","date":"2021","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/33406419","citation_count":30,"is_preprint":false},{"pmid":"10873612","id":"PMC_10873612","title":"Isolation of two novel human RhoGEFs, ARHGEF3 and ARHGEF4, in 3p13-21 and 2q22.","date":"2000","source":"Biochemical and biophysical research 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genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18499081","citation_count":29,"is_preprint":false},{"pmid":"21715309","id":"PMC_21715309","title":"Silencing of RhoA nucleotide exchange factor, ARHGEF3, reveals its unexpected role in iron uptake.","date":"2011","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/21715309","citation_count":28,"is_preprint":false},{"pmid":"28542600","id":"PMC_28542600","title":"SNP in human ARHGEF3 promoter is associated with DNase hypersensitivity, transcript level and platelet function, and Arhgef3 KO mice have increased mean platelet volume.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28542600","citation_count":22,"is_preprint":false},{"pmid":"24840563","id":"PMC_24840563","title":"Influence of ARHGEF3 and RHOA knockdown on ACTA2 and other genes in osteoblasts and osteoclasts.","date":"2014","source":"PloS 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Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/23192023","citation_count":3,"is_preprint":false},{"pmid":"40634490","id":"PMC_40634490","title":"Plasma extracellular vesicle-associated miR-512-3p modulates angiogenesis in pediatric Moyamoya disease by targeting ARHGEF3.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/40634490","citation_count":1,"is_preprint":false},{"pmid":"39314354","id":"PMC_39314354","title":"ARHGEF3 Regulates Hair Follicle Morphogenesis.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39314354","citation_count":0,"is_preprint":false},{"pmid":"42023986","id":"PMC_42023986","title":"Tumor-Intrinsic ARHGEF3 Enhances Antitumor Immunity by Promoting T-Cell Infiltration and Limiting Myeloid Cell-Mediated Immunosuppression.","date":"2026","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/42023986","citation_count":0,"is_preprint":false},{"pmid":"42142076","id":"PMC_42142076","title":"Selected ARHGEF3 Gene Polymorphisms Associated With Platelet Hyperaggregability in Patients With Venous Thromboembolism.","date":"2026","source":"Clinical and applied thrombosis/hemostasis : official journal of the International Academy of Clinical and Applied Thrombosis/Hemostasis","url":"https://pubmed.ncbi.nlm.nih.gov/42142076","citation_count":0,"is_preprint":false},{"pmid":"41490244","id":"PMC_41490244","title":"The Rho GTPase regulator ARHGEF3 orchestrates hair placode budding by coordinating cell fate and P-cadherin patterning in mice.","date":"2026","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/41490244","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":17631,"output_tokens":4945,"usd":0.063534,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13170,"output_tokens":4744,"usd":0.092225,"stage2_stop_reason":"end_turn"},"total_usd":0.155759,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"XPLN (ARHGEF3) is a guanine nucleotide exchange factor that stimulates GDP-to-GTP exchange on RhoA and RhoB but not RhoC, RhoG, Rac1, or Cdc42 in vitro, and the selectivity against RhoC is determined by isoleucine 43 in RhoC (valine in RhoA/RhoB). XPLN preferentially associates with RhoA and RhoB, and when expressed in cells stimulates stress fiber and focal adhesion assembly in a Rho kinase-dependent manner.\",\n      \"method\": \"In vitro nucleotide exchange assay, co-precipitation/binding assay, cell overexpression with dominant-negative Rho kinase and active RhoA mutants, focus formation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of GEF activity with mutagenesis identifying the discriminating residue (Ile43), combined with cell-based epistasis and binding assays in one rigorous study\",\n      \"pmids\": [\"12221096\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Crystal structure of the tandem DH-PH domains of mouse XPLN (ARHGEF3) was determined at 1.79 Å resolution by multiwavelength anomalous dispersion. The structure revealed an α4-α5 loop in the DH domain that is flexible and intramolecular DH-PH interactions, suggesting PH-domain rearrangement occurs upon RhoA binding. High structural similarity to other RhoGEFs (NET1, PDZ-RhoGEF, LARG, ITSN1/2) was observed.\",\n      \"method\": \"X-ray crystallography (MAD phasing, 1.79 Å resolution)\",\n      \"journal\": \"Acta crystallographica. Section F, Structural biology and crystallization communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure at high resolution with functional interpretation; single study but direct structural determination\",\n      \"pmids\": [\"23192023\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"XPLN (ARHGEF3) interacts with mTORC2 (but not mTORC1) in a rictor-dependent manner and acts as an endogenous inhibitor of mTORC2 kinase activity toward Akt. Knockdown of XPLN enhances Akt Ser473 phosphorylation; overexpression suppresses it. Purified XPLN inhibits mTORC2 kinase activity in vitro without affecting mTORC1. The GEF activity of XPLN is dispensable for mTORC2 inhibition, whereas the N-terminal 125-amino-acid fragment is necessary and sufficient for mTORC2 inhibition and for negative regulation of myoblast differentiation.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation, siRNA knockdown, overexpression, in vitro mTORC2 kinase assay with purified components, domain deletion analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro reconstituted kinase inhibition with purified XPLN, complemented by reciprocal Co-IP, domain mapping, and genetic rescue experiments, all in one study\",\n      \"pmids\": [\"24043828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In AML cells (U937), ARHGEF3 protein is primarily nuclear but undergoes cytoplasmic translocation upon HDACi (MS275) treatment. Cytoplasmic ARHGEF3 activates the RhoA/ROCK pathway, leading to SAPK/JNK phosphorylation and Elk1 activation. ARHGEF3 silencing prevents RhoA activation, reduces SAPK/JNK phosphorylation and Elk1 activity, and blocks CD68 macrophage differentiation marker expression.\",\n      \"method\": \"siRNA knockdown, immunofluorescence/subcellular fractionation for localization, Rho activation assay (GTP-RhoA pulldown), western blotting for pathway components, pharmacological inhibitors (C3 transferase, Y27632)\",\n      \"journal\": \"Epigenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — localization tied to functional consequence, RhoA activation measured directly, multiple inhibitor validations; single lab\",\n      \"pmids\": [\"25494542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Silencing of arhgef3 in zebrafish causes microcytic hypochromic anemia rescued by intracellular iron supplementation, demonstrating that ARHGEF3 regulates transferrin/iron uptake in erythroid cells. Silencing of RhoA phenocopies arhgef3 loss. In K562 cells, ARHGEF3 knockdown severely impairs transferrin uptake, placing ARHGEF3 upstream of RhoA in an iron-uptake pathway.\",\n      \"method\": \"Morpholino knockdown in zebrafish, rescue by iron injection, siRNA knockdown in K562 cells, transferrin uptake assay\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (arhgef3/RhoA knockdown + rescue), direct functional assay (transferrin uptake); single lab, two model systems\",\n      \"pmids\": [\"21715309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ARHGEF3 KO mice show enhanced skeletal muscle mass, fiber size, and function after acute injury. This effect requires the GEF activity of ARHGEF3 (not Akt signaling) and operates via the RhoA/ROCK pathway. ARHGEF3 KO promotes autophagy, and autophagy activation is required for the enhanced regeneration phenotype. Overexpression of ARHGEF3 inhibits muscle regeneration in a ROCK-dependent manner. In aged mice, ARHGEF3 depletion prevents muscle weakness by restoring autophagy.\",\n      \"method\": \"Knockout mouse model (ARHGEF3-KO), acute muscle injury model, GEF-inactive mutant overexpression, ROCK inhibitor treatment, autophagy flux assays, muscle function measurements\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO with multiple orthogonal phenotypic readouts, GEF-inactive mutant distinguishing GEF vs non-GEF functions, pharmacological epistasis with ROCK inhibitor; replicated across age groups\",\n      \"pmids\": [\"33406419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"XPLN (ARHGEF3) knockdown in human lung fibroblasts stimulates SPARC expression and Akt Ser473 phosphorylation. TGF-β1 downregulates XPLN via Smad2/3. HDACi treatment upregulates XPLN mRNA and reverses TGF-β1-induced SPARC expression, establishing XPLN as a negative regulator of the mTORC2-SPARC axis.\",\n      \"method\": \"siRNA knockdown, western blotting and qRT-PCR for SPARC and pAkt, TGF-β1/Smad pathway analysis, HDAC inhibitor treatment\",\n      \"journal\": \"Pulmonary pharmacology & therapeutics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single lab, multiple validated readouts but no in vitro reconstitution; mechanism consistent with established mTORC2 role\",\n      \"pmids\": [\"28315487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ARHGEF3 knockdown in osteoblast-like cells causes downregulation of TNFRSF11B (osteoprotegerin). RHOA knockdown in osteoblast-like cells downregulates ACTA2 (alpha-2 actin) and upregulates PTH1R, and in osteoclast-like cells downregulates ARHGDIA and ACTA2, placing ARHGEF3/RhoA upstream of these bone-cell gene-expression programs.\",\n      \"method\": \"siRNA knockdown, microarray followed by qRT-PCR validation in multiple human osteoblast-like and osteoclast-like cell lines\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — knockdown with transcriptional readout validated by qRT-PCR; multiple cell lines; no direct enzymatic or binding assay\",\n      \"pmids\": [\"24840563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ARHGEF3 overexpression inhibits HCV subgenomic replicon RNA replication and full-length HCV replication, as well as replication of yellow fever virus and Zika virus (Flaviviridae), in cell-based systems. This antiviral activity is conserved between human and rhesus macaque ARHGEF3.\",\n      \"method\": \"Lentiviral overexpression screen with luciferase-expressing HCV replicons, independent validation with full-length HCV infection assay and flavivirus replication assays\",\n      \"journal\": \"Viruses\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — cell-based overexpression validated in multiple viral systems; mechanism of antiviral action not defined at molecular level\",\n      \"pmids\": [\"36016278\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ARHGEF3 promotes NSCLC cell proliferation in vitro and in vivo by stabilizing ATP-citrate lyase (ACLY) protein: ARHGEF3 reduces acetylation of ACLY on Lys17 and Lys86, preventing ACLY interaction with its E3 ubiquitin ligase NEDD4 and subsequent degradation. This function is independent of ARHGEF3's GEF activity.\",\n      \"method\": \"siRNA knockdown and overexpression, xenograft model, co-immunoprecipitation (ACLY-NEDD4 interaction), acetylation site mapping, GEF-inactive mutant\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP demonstrating ACLY-NEDD4 dissociation, acetylation site identification, GEF-inactive mutant distinguishing mechanism; single lab\",\n      \"pmids\": [\"36241648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ARHGEF3 is elevated in dystrophic mdx muscles and drives RhoA/ROCK activation. ARHGEF3 KO in mdx mice restores muscle quality (force production) and morphology without affecting regeneration. ARHGEF3 overexpression further compromises mdx muscle quality in a GEF activity- and ROCK-dependent manner. The ARHGEF3/ROCK pathway impairs muscle function by blocking autophagy flux, as chloroquine-mediated autophagy inhibition abolishes the benefit of ARHGEF3/ROCK inhibition.\",\n      \"method\": \"Arhgef3 KO in mdx mice, 3D-engineered mdx muscle model, ROCK inhibitor (Y-27632), GEF-inactive mutant overexpression, autophagy flux assay with chloroquine, muscle force measurements\",\n      \"journal\": \"Journal of cachexia, sarcopenia and muscle\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO + pharmacological and genetic rescue in two muscle models, GEF-inactive mutant, autophagy epistasis; orthogonal to companion paper (PMID:33406419)\",\n      \"pmids\": [\"37311604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ARHGEF3 promotes adipocyte hypertrophy and differentiation through two coordinated mechanisms: (1) RhoA-dependent facilitation of YAP nuclear translocation and YAP binding to the RhoA promoter, and (2) enhancement of PPARγ transcriptional activity, establishing a reciprocal activation loop. ARHGEF3-deficient mice on a high-fat diet show reduced weight gain and smaller adipocyte size correlated with decreased RhoA expression and altered cytoskeletal dynamics.\",\n      \"method\": \"ARHGEF3-KO mice on HFD, in vitro adipogenesis (C3H10T1/2 cells), ChIP for YAP-RhoA promoter binding, co-immunoprecipitation, luciferase reporter for PPARγ activity, immunostaining for YAP localization\",\n      \"journal\": \"Journal of advanced research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — ChIP, Co-IP, reporter assay, and KO mouse; single lab; YAP-RhoA promoter binding is novel but needs independent replication\",\n      \"pmids\": [\"40216078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Tumor-intrinsic ARHGEF3 activates the RHOA-ROCK-PTEN cascade to inhibit AKT signaling, which upregulates IRF1-dependent chemokines CXCL10 and CXCL11 (promoting T-cell infiltration) and suppresses FASN-mediated fatty acid synthesis (limiting myeloid immunosuppression). These dual effects reshape the tumor microenvironment toward T-cell inflammation.\",\n      \"method\": \"Cell-based gain/loss-of-function, RhoA activity assay, pathway inhibitors, CXCL10/11 measurement, FASN activity assay, in vivo tumor models\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple pathway readouts with genetic and pharmacological epistasis; single lab, novel pathway; not yet independently replicated\",\n      \"pmids\": [\"42023986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ARHGEF3 restricts placode cell fate acquisition and establishes a radial gradient of P-cadherin (but not E-cadherin) across hair follicle placodes during embryonic development. In Arhgef3-KO embryos, placodes are enlarged with elevated P-cadherin at junctions and disrupted gradient, correlating with aberrant epithelial organization and altered hair follicle downgrowth geometry.\",\n      \"method\": \"Arhgef3 KO mouse embryos, immunostaining for P-cadherin and E-cadherin, hair follicle morphometry, cell culture models for F-actin accumulation\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with specific cadherin patterning phenotype, distinguishing P- vs E-cadherin; single lab, peer-reviewed\",\n      \"pmids\": [\"41490244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"miR-451a directly binds the 3'-UTR of ARHGEF3 mRNA (confirmed by dual-luciferase reporter assay), and knockdown of ARHGEF3 in K562 cells reverses hydroquinone-induced suppression of erythroid differentiation, placing ARHGEF3 as a downstream effector of the miR-451a/c-Jun axis in erythroid maturation.\",\n      \"method\": \"Dual-luciferase 3'-UTR reporter assay, siRNA knockdown, erythroid differentiation assays in K562 cells\",\n      \"journal\": \"Toxicology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct 3'-UTR validation combined with functional knockdown; consistent with prior erythroid role (PMID:21715309); single lab\",\n      \"pmids\": [\"38801936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Inhibition of miR-512-3p in Moyamoya disease endothelial colony-forming cells increases ARHGEF3 expression and downstream RhoA GTPase activity, leading to enhanced tubule formation (angiogenesis rescue). Bioinformatics and functional data identify ARHGEF3 as a direct target of miR-512-3p.\",\n      \"method\": \"miR-512-3p inhibition in primary ECFCs, GTPase activity assay, tubule formation assay, western blotting for ARHGEF3/RhoA\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, no 3'-UTR reporter validation for ARHGEF3 targeting reported; functional link is indirect\",\n      \"pmids\": [\"40634490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ARHGEF3 promotes F-actin accumulation at the cell cortex and P-cadherin enrichment at cell-cell junctions in culture models, consistent with its role in hair placode morphogenesis.\",\n      \"method\": \"Cell culture overexpression, phalloidin staining for F-actin, immunostaining for P-cadherin\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single overexpression experiment; findings later incorporated into peer-reviewed version (PMID:41490244)\",\n      \"pmids\": [\"39314354\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ARHGEF3 (XPLN) is a DH-PH domain-containing guanine nucleotide exchange factor that selectively activates RhoA and RhoB (but not RhoC, owing to Ile43 in RhoC) to drive actin cytoskeletal remodeling, stress fiber formation, and diverse downstream programs including autophagy regulation in skeletal muscle, transferrin/iron uptake in erythroid cells, and P-cadherin patterning in hair follicle morphogenesis; independently of its GEF activity, ARHGEF3 also binds mTORC2 via rictor and inhibits mTORC2 kinase activity toward Akt through its N-terminal 125-amino-acid domain, and stabilizes ACLY protein by reducing its acetylation, making ARHGEF3 a bifunctional regulator with both canonical Rho-GEF and non-canonical mTORC2/protein-stability functions.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ARHGEF3 (XPLN) is a DH-PH domain guanine nucleotide exchange factor that selectively activates RhoA and RhoB to drive actin cytoskeletal remodeling, stress fiber and focal adhesion assembly through Rho kinase, while also executing GEF-independent regulatory functions [#0, #1]. Its enzymatic specificity is intrinsic: ARHGEF3 catalyzes GDP-to-GTP exchange on RhoA and RhoB but not RhoC, a discrimination set by isoleucine 43 of RhoC, and its tandem DH-PH module undergoes PH-domain rearrangement upon RhoA engagement [#0, #1]. Through this RhoA/ROCK axis ARHGEF3 governs diverse programs in vivo: it restrains skeletal muscle mass, fiber size, and regeneration by blocking autophagy flux, an activity that requires GEF function and is recapitulated in dystrophic mdx muscle [#5, #10]; it supports erythroid transferrin/iron uptake upstream of RhoA [#4]; and it shapes P-cadherin gradients and placode cell fate during hair follicle morphogenesis [#13]. ARHGEF3 carries a separable, GEF-independent activity through its N-terminal 125-amino-acid domain that binds mTORC2 via rictor and inhibits its kinase activity toward Akt Ser473, thereby negatively regulating myoblast differentiation and the mTORC2-SPARC axis [#2, #6]. In a further non-canonical role, ARHGEF3 stabilizes ATP-citrate lyase by reducing its acetylation and blocking NEDD4-mediated degradation to promote tumor cell proliferation [#9]. Additional context-specific roles in AML macrophage differentiation, adipocyte hypertrophy, antiviral restriction, and tumor microenvironment remodeling have been described [#3, #11, #8, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing whether ARHGEF3 is a functional GEF and which Rho GTPases it acts on defined its core biochemical identity and the structural basis of its selectivity.\",\n      \"evidence\": \"In vitro nucleotide exchange and binding assays with mutagenesis (Ile43), plus cell overexpression with dominant-negative Rho kinase\",\n      \"pmids\": [\"12221096\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish physiological contexts where RhoA vs RhoB activation matters\", \"Did not address GEF-independent functions\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Linking ARHGEF3 to erythroid iron handling showed that its Rho-GEF activity has a tissue-specific physiological output beyond cytoskeletal assembly.\",\n      \"evidence\": \"Morpholino knockdown in zebrafish with iron rescue, siRNA and transferrin uptake assay in K562 cells\",\n      \"pmids\": [\"21715309\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between RhoA activity and transferrin uptake machinery undefined\", \"Single lab across two model systems\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Solving the tandem DH-PH structure provided the structural rationale for substrate engagement and conformational change upon RhoA binding.\",\n      \"evidence\": \"X-ray crystallography at 1.79 Å by MAD phasing\",\n      \"pmids\": [\"23192023\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No co-crystal with RhoA/RhoB to confirm the inferred PH rearrangement\", \"N-terminal mTORC2-binding region not in the construct\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovery that ARHGEF3 binds and inhibits mTORC2 independently of its GEF activity revealed it as a bifunctional protein with a separable N-terminal regulatory module.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal Co-IP, in vitro mTORC2 kinase assay with purified XPLN, and domain deletion mapping to N-terminal 125 aa\",\n      \"pmids\": [\"24043828\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of rictor/mTORC2 binding unresolved\", \"How GEF and mTORC2-inhibitory activities are coordinated unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Knockdown transcriptomics placed ARHGEF3/RhoA upstream of bone-cell gene-expression programs, extending its reach to transcriptional outputs.\",\n      \"evidence\": \"siRNA knockdown with microarray and qRT-PCR validation in osteoblast- and osteoclast-like lines\",\n      \"pmids\": [\"24840563\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct enzymatic or binding assay connecting ARHGEF3 to the transcriptional changes\", \"Mechanism of gene regulation unmapped\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showing nuclear-to-cytoplasmic relocation upon HDAC inhibition coupled ARHGEF3 localization to RhoA/ROCK-driven myeloid differentiation, indicating regulated subcellular activity.\",\n      \"evidence\": \"siRNA, fractionation/immunofluorescence, GTP-RhoA pulldown, and pharmacological inhibitors in U937 AML cells\",\n      \"pmids\": [\"25494542\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of nuclear retention and HDACi-triggered export unknown\", \"Single cell line\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrating that ARHGEF3 negatively regulates the mTORC2-SPARC axis and is itself suppressed by TGF-β1/Smad reinforced its mTORC2-inhibitory role and revealed an upstream control input.\",\n      \"evidence\": \"siRNA knockdown, western blot/qRT-PCR for SPARC and pAkt, TGF-β1/Smad and HDACi treatments in lung fibroblasts\",\n      \"pmids\": [\"28315487\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vitro reconstitution of the SPARC link\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"An ARHGEF3 KO mouse demonstrated that its GEF activity restrains skeletal muscle regeneration by blocking autophagy, separating the GEF function from Akt signaling in vivo.\",\n      \"evidence\": \"KO mouse, acute injury model, GEF-inactive mutant, ROCK inhibitor, and autophagy flux assays across ages\",\n      \"pmids\": [\"33406419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RhoA/ROCK suppresses autophagy mechanistically not defined\", \"Relevant muscle cell type for the effect not fully resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identification of ACLY stabilization showed a second GEF-independent function in which ARHGEF3 controls protein stability via acetylation.\",\n      \"evidence\": \"siRNA/overexpression, xenografts, ACLY-NEDD4 Co-IP, acetylation site mapping (K17/K86), and GEF-inactive mutant in NSCLC\",\n      \"pmids\": [\"36241648\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How ARHGEF3 reduces ACLY acetylation enzymatically unknown\", \"Whether ARHGEF3 acts directly on ACLY or via an intermediary unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"An overexpression screen revealed antiviral restriction against Flaviviridae, expanding ARHGEF3's functional repertoire to host defense.\",\n      \"evidence\": \"Lentiviral overexpression with HCV replicons and full-length HCV, plus YFV/ZIKV replication assays; conserved in rhesus ARHGEF3\",\n      \"pmids\": [\"36016278\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of antiviral action undefined\", \"Whether GEF activity is required not tested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Genetic and pharmacological dissection in mdx muscle confirmed that the ARHGEF3/ROCK pathway impairs muscle quality by blocking autophagy flux, validating the autophagy mechanism in a disease setting.\",\n      \"evidence\": \"Arhgef3 KO in mdx mice, 3D-engineered muscle, ROCK inhibitor, GEF-inactive mutant, chloroquine autophagy epistasis, force measurements\",\n      \"pmids\": [\"37311604\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream signals elevating ARHGEF3 in dystrophic muscle unknown\", \"Molecular link from ROCK to autophagy machinery not detailed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"miR-451a was shown to directly target the ARHGEF3 3'-UTR, identifying a post-transcriptional control point governing its erythroid role.\",\n      \"evidence\": \"Dual-luciferase 3'-UTR reporter, siRNA knockdown, and erythroid differentiation assays in K562 cells\",\n      \"pmids\": [\"38801936\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream effector mechanism in erythroid maturation not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"ARHGEF3 was placed in an adipogenic loop coupling RhoA-dependent YAP nuclear translocation with PPARγ activity, linking it to metabolic tissue expansion.\",\n      \"evidence\": \"KO mice on HFD, in vitro adipogenesis, ChIP for YAP-RhoA promoter binding, Co-IP, PPARγ luciferase reporter, YAP immunostaining\",\n      \"pmids\": [\"40216078\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"YAP-RhoA promoter binding needs independent replication\", \"Direct molecular partner connecting ARHGEF3 to YAP unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A RHOA-ROCK-PTEN-AKT cascade was shown to remodel the tumor microenvironment via IRF1-driven chemokines and FASN suppression, connecting ARHGEF3 GEF signaling to anti-tumor immunity.\",\n      \"evidence\": \"Gain/loss-of-function, RhoA activity assay, pathway inhibitors, CXCL10/11 and FASN readouts, in vivo tumor models\",\n      \"pmids\": [\"42023986\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, novel pathway not independently replicated\", \"Mechanistic link from ROCK to PTEN not detailed\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A KO embryo study established that ARHGEF3 patterns P-cadherin gradients and restricts placode fate, demonstrating a developmental morphogenesis role tied to cytoskeletal control.\",\n      \"evidence\": \"Arhgef3 KO mouse embryos, P-/E-cadherin immunostaining, hair follicle morphometry, F-actin culture models\",\n      \"pmids\": [\"41490244\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How ARHGEF3 selectively controls P- but not E-cadherin unknown\", \"Link between RhoA activity and cadherin gradient unmapped\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how ARHGEF3's GEF-dependent (RhoA/RhoB/ROCK) and GEF-independent (mTORC2 inhibition, ACLY stabilization) activities are integrated, regulated, and partitioned across the diverse tissue contexts in which it acts.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model coordinating the two functional modes\", \"No structure of full-length ARHGEF3 with its N-terminal mTORC2-binding region\", \"Tissue-specific regulation of ARHGEF3 expression and localization incompletely defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 9]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 5, 12]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5, 10]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RHOA\", \"RHOB\", \"RICTOR\", \"ACLY\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}