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ARHGEF18

Rho guanine nucleotide exchange factor 18 · UniProt Q6ZSZ5

Length
1361 aa
Mass
151.6 kDa
Annotated
2026-06-09
21 papers in source corpus 14 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: tie faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

ARHGEF18 (p114RhoGEF) is a Dbl-family guanine nucleotide exchange factor that drives spatially restricted RhoA activation at epithelial and endothelial cell junctions to organize cortical actomyosin, control apicobasal polarity, and maintain barrier integrity (PMID:21258369, PMID:23698346). Through its DH/PH catalytic module it activates RhoA (and Rac1, but not Cdc42), and a patient-derived DH-domain missense variant that weakens RHOA binding establishes this domain as essential for exchange activity (PMID:14512443, PMID:28132693). Once active, it signals predominantly through a ROCK–myosin II axis: at cell-cell contacts it stimulates myosin light chain double phosphorylation to power collective epithelial migration and amoeboid invasion, and it acts upstream of ROCK2 and myosin IIA to control apical junction assembly, circumferential actomyosin belt formation, retinal neuroepithelial polarity, and lumen consolidation during tubulogenesis (PMID:23698346, PMID:23185572, PMID:26483385, PMID:26217016). Its junctional recruitment and activation are governed by multiple upstream inputs, including heterotrimeric G-protein subunits Gβγ and Gα12, the FERM protein Lulu2 (antagonized by aPKC phosphorylation) with PDZ-mediated recruitment by Patj, LKB1, the CRB3A–Ehm2 polarity module, and the Wnt effectors Dishevelled and Daam1 (PMID:14512443, PMID:22006950, PMID:23648482, PMID:20810787, PMID:26217016, PMID:31051012). Beyond epithelia, ARHGEF18 supports endothelial mechanotransduction, where shear-stress-dependent phosphorylation directs its association with tight junctions to maintain the vascular barrier, drives PKA/CREB-coupled actomyosin remodeling required for trophoblast fusion, and is activated by an isoform-specific SEPTIN9 interaction at mitochondrial fission sites to promote calcium influx and inner-membrane constriction (PMID:33842485, PMID:40920138, PMID:39977269).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2003 High

    Established a direct receptor-proximal input to p114RhoGEF by showing Gβγ subunits bind its catalytic DH/PH domain and stimulate exchange toward RhoA and Rac1, defining its GTPase specificity.

    Evidence Co-IP, in vivo Rho pull-downs with dominant negatives, SRE reporter, and transducin scavenging in cells

    PMID:14512443

    Open questions at the time
    • Did not localize this activity to junctions
    • No structural basis for Gβγ–DH/PH contact
  2. 2010 Medium

    Connected ARHGEF18 to Wnt signaling by showing it binds Dishevelled and Daam1 and is required for Wnt-3a/Dvl-induced RhoA activation and neurite retraction.

    Evidence shRNA knockdown, RhoA pull-down, Co-IP, and dominant-negative Dvl-binding domain in neuroblastoma cells

    PMID:20810787

    Open questions at the time
    • No direct demonstration that Dvl activates GEF catalysis
    • Cell-type restricted to neuroblastoma
  3. 2011 High

    Defined the core junctional function: ARHGEF18 produces junction-restricted RhoA activation within a myosin II/ROCK II/cingulin complex, explaining how Rho signaling is spatially confined during junction assembly.

    Evidence Reciprocal Co-IP, RNAi with RhoA-GTP pulldowns, myosin phosphorylation readouts, and immunofluorescence in epithelial cells

    PMID:21258369

    Open questions at the time
    • Mechanism restricting non-junctional Rho not fully resolved
    • How cingulin recruits the GEF unclear
  4. 2011 High

    Identified upstream activators and recruiters at apical junctions, showing Lulu2 binds and activates the GEF (antagonized by aPKC phosphorylation) and Patj recruits it via a PDZ interaction.

    Evidence Co-IP, RNAi, GEF activity assays, aPKC phosphorylation experiments, and immunofluorescence

    PMID:22006950

    Open questions at the time
    • Structural basis of Lulu2–GEF activation not defined
    • Interplay between Patj recruitment and Lulu2 activation unresolved
  5. 2012 Medium

    Distinguished the biochemical output of ARHGEF18 at contacts as myosin light chain double phosphorylation, linking it to collective migration and amoeboid invasion.

    Evidence RNAi, single vs. double MLC phosphorylation assays, Rho/Rac pulldowns, 3D invasion, and traction force measurements

    PMID:23185572

    Open questions at the time
    • Mechanism of reciprocal Rac increase upon depletion unknown
    • Single-lab observation
  6. 2013 High

    Extended the activator repertoire and placed the pathway in vivo: LKB1 forms a kinase-independent complex with the GEF to promote apical junction assembly, and a RhoA→ROCK2 cascade maintains retinal neuroepithelial polarity, with human ARHGEF18 rescuing the medaka mutant.

    Evidence Co-IP and kinase-dead LKB1 in bronchial cells; genetic loss-of-function, ROCK2 epistasis, and cross-species rescue in medaka retina

    PMID:23648482 PMID:23698346

    Open questions at the time
    • How kinase-independent LKB1 binding modulates GEF activity unclear
    • Link between polarity and proliferative-vs-neurogenic divisions mechanistically incomplete
  7. 2015 Medium

    Defined additional recruitment/activation inputs and a tubulogenesis role: CRB3A recruits the GEF and its activator Ehm2 to build the actomyosin belt, and the GEF acts upstream of ROCK–myosin IIA for lumen consolidation.

    Evidence Co-IP and CRB3A tail mutants with RhoA pulldowns; shRNA plus ROCK/myosin IIA inhibitors and live imaging in 3D MDCK cysts

    PMID:26217016 PMID:26483385

    Open questions at the time
    • Mechanism of Ehm2 activation of the GEF undefined
    • Single-lab findings
  8. 2016 Medium

    Mapped a distinct Gα12-binding region in the C-terminus, showing G-protein input via an interface separate from the canonical RH domain used by other RhoGEFs.

    Evidence Co-IP, Gα12/13 chimeras, charge-reversal mutagenesis, and dominant-negative Gα12 in reporter assays

    PMID:31051012

    Open questions at the time
    • No structure of the Gα12–GEF interface
    • Functional consequence of Gα12 vs Gβγ inputs not compared
  9. 2017 Low

    Functionally validated the DH domain in a disease context by showing a patient p.Thr270Ala variant reduces RHOA interaction and activation.

    Evidence Patient mutation analysis and a RHOA interaction/activation assay for the DH-domain variant

    PMID:28132693

    Open questions at the time
    • Described without detailed biochemical reconstitution
    • Disease mechanism beyond reduced RHOA activation not established
  10. 2021 Medium

    Broadened the role to development by showing ARHGEF18 couples actomyosin/junction dynamics to PKA/CREB signaling for syncytiotrophoblast fusion and placentation.

    Evidence In vitro trophoblast differentiation, conditional knockout mice, cAMP/PKA stimulation, CREB reporters, and AKAP12 expression analysis

    PMID:33842485

    Open questions at the time
    • How GEF activity controls AKAP12 expression unclear
    • Direct link from RhoA to CREB transcription not resolved
  11. 2025 Medium

    Revealed two new contexts—endothelial mechanotransduction and mitochondrial fission—where phosphorylation directs junction binding for barrier maintenance and SEPTIN9 isoform-specific binding activates the GEF upstream of fission-site calcium influx.

    Evidence Shear-stress and phosphorylation assays, Co-IP with tight junction proteins, in vivo vascular permeability assays; live imaging of fission sites, SEPTIN9 isoform knockdown, and mitochondrial calcium measurements

    PMID:39977269 PMID:40920138

    Open questions at the time
    • Kinase that phosphorylates ARHGEF18 under shear stress not identified
    • How a junction-associated RhoGEF acts at mitochondria mechanistically unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • How distinct upstream inputs (Gβγ, Gα12, Lulu2/Patj, LKB1, CRB3A-Ehm2, SEPTIN9, phosphorylation) are integrated to select among ARHGEF18's diverse outputs across junctions, mitochondria, and transcriptional programs remains unresolved.
  • No unifying structural model of activation
  • No quantitative comparison of input strength or competition
  • Substrate/effector switching between RhoA and Rac1 in different contexts not mechanistically defined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 5
Localization
GO:0005856 cytoskeleton 3 GO:0005886 plasma membrane 3 GO:0005739 mitochondrion 1
Pathway
R-HSA-1500931 Cell-Cell communication 3 R-HSA-162582 Signal Transduction 3 R-HSA-1266738 Developmental Biology 2
Partners
CGNCRB3LLGL2PATJRHOAROCK2SEPTIN9STK11

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 p114RhoGEF (ARHGEF18) is a junction-associated protein that drives spatially restricted RhoA activation at epithelial junctions; it associates with a complex containing myosin II, ROCK II, and the junctional adaptor cingulin, and its depletion abolishes junction-associated RhoA activation while stimulating non-junctional Rho signaling and basal myosin phosphorylation. Co-immunoprecipitation, RNAi knockdown with RhoA activity assays, myosin phosphorylation readouts, immunofluorescence localization Nature cell biology High 21258369
2003 Gβγ subunits of heterotrimeric G proteins directly interact with the DH/PH domain of p114RhoGEF and stimulate its guanine nucleotide exchange activity toward RhoA and Rac1 (but not Cdc42), leading to actin stress fiber formation, cell rounding, and NADPH oxidase-dependent ROS production. Co-immunoprecipitation, in vivo Rho pull-down assays with dominant-negative mutants, serum response element transcription reporter assay, Gβγ scavenger (transducin) inhibition Circulation research High 14512443
2011 Lulu2 (a FERM-domain protein) directly interacts with and activates p114RhoGEF at apical cell-cell junctions to regulate the circumferential actomyosin belt; this interaction is negatively regulated by aPKC-mediated phosphorylation of the FERM-adjacent domain of Lulu2. Additionally, Patj recruits p114RhoGEF to apical junctions via PDZ domain-mediated interaction. Co-immunoprecipitation, RNAi knockdown, GEF activity assays, phosphorylation experiments with aPKC, immunofluorescence localization The Journal of cell biology High 22006950
2013 LKB1 interacts with p114RhoGEF in a kinase-activity-independent manner and together they control RhoA activity to promote apical junction assembly in human bronchial epithelial cells. Co-immunoprecipitation, RNAi knockdown, RhoA-GTP pull-down assay, LKB1 kinase-dead mutant analysis Molecular and cellular biology Medium 23648482
2010 p114-RhoGEF binds to Dishevelled (Dvl) and Daam1 and is required for Wnt-3a/Dvl-induced RhoA activation and neurite retraction in neuroblastoma cells; shRNA-mediated depletion of p114-RhoGEF suppresses Dvl-induced neurite retraction and RhoA activation, and overexpression of the Dvl-binding domain of p114-RhoGEF acts as a dominant negative. shRNA knockdown, in vivo RhoA pull-down assay, co-immunoprecipitation, dominant-negative domain overexpression Molecular biology of the cell Medium 20810787
2013 ArhGEF18-mediated RhoA activation signals through Rock2 to maintain apicobasal polarity, tight junction localization, cortical actin organization, and control of neurogenic vs. proliferative cell divisions in the vertebrate retinal neuroepithelium; human ARHGEF18 rescues the medaka arhgef18 mutant phenotype. Genetic loss-of-function (medaka mutation), epistasis with Rock2, rescue with human ARHGEF18, immunofluorescence for tight junction and actin markers Development (Cambridge, England) High 23698346
2012 p114RhoGEF drives cortical myosin activation specifically by stimulating myosin light chain double phosphorylation at cell-cell contacts, promoting collective epithelial cell migration and amoeboid-like tumor cell invasion on Matrigel; depletion reduces RhoA but increases Rac activity. RNAi knockdown, myosin light chain phosphorylation assays (single vs. double phosphorylation), Rho/Rac activity pulldowns, 3D invasion assays, traction force measurements PloS one Medium 23185572
2015 p114RhoGEF controls later stages of tubulogenesis (lumen consolidation) through a ROCK–myosin IIA pathway; knockdown causes multiple lumens per tube, and inhibition of ROCK or myosin IIA phenocopies this, with live imaging showing that cell movement required for lumen consolidation is blocked. shRNA knockdown, ROCK inhibitor, myosin IIA inhibitor, live-cell imaging, 3D tubulogenesis assay in MDCK cells Journal of cell science Medium 26483385
2015 CRB3A recruits p114RhoGEF and its activator Ehm2 to the cell periphery via both cytoplasmic tail motifs, increasing RhoA activation; ROCK1/2 act downstream to remodel the cytoskeleton into a circumferential actomyosin belt and change cell morphology. Co-immunoprecipitation, CRB3A tail mutant analysis, RhoA-GTP pull-down, RNAi knockdown of p114RhoGEF, immunofluorescence Molecular and cellular biology Medium 26217016
2016 p114RhoGEF contains a C-terminal region that specifically binds Gα12 (but not Gα13); charge-reversal mutagenesis of conserved residues disrupts this interaction. This region is distinct from the RH domain interface used by other RhoGEFs, and Gα12 dominant-negative suppresses serum-mediated signaling to p114RhoGEF in cells. Co-immunoprecipitation, Gα12/13 chimera analysis, charge-reversal mutagenesis, dominant-negative Gα12/13 in cell-based reporter assay Journal of molecular signaling Medium 31051012
2021 ARHGEF18/p114RhoGEF is required for syncytiotrophoblast differentiation and placenta development; it controls expression of AKAP12 (a PKA scaffold), is required for PKA-induced actomyosin remodeling, and enables CREB-driven transcription of fusogenic proteins, thereby linking actomyosin dynamics and cell-cell junctions to PKA/CREB signaling and trophoblast cell-cell fusion. In vitro trophoblast differentiation assays, conditional knockout mice, cAMP/PKA stimulation with actomyosin readouts, CREB reporter assays, AKAP12 expression analysis Frontiers in cell and developmental biology Medium 33842485
2025 SEPTIN9 is present at mitochondrial fission sites from early stages and activates ARHGEF18 through an isoform-specific N-terminal interaction; loss of SEPTIN9 impairs mitochondrial calcium influx, placing SEPTIN9–ARHGEF18 upstream of calcium flux and inner membrane constriction during early mitochondrial fission. Live-cell imaging of fission sites, Co-IP/interaction assays, SEPTIN9 isoform knockdown, mitochondrial calcium flux measurements, DRP1 recruitment timing analysis The Journal of cell biology Medium 40920138
2025 ARHGEF18 phosphorylation is modulated by shear stress magnitude in endothelial cells; when phosphorylated, ARHGEF18 interacts with tight junctions and is required for EC elongation, alignment, migration, tight junction formation, and maintenance of the endothelial barrier and vascular permeability in vivo. Shear stress experiments, phosphorylation assays, Co-IP with tight junction proteins, RNAi knockdown, in vivo mouse vascular permeability assay, immunofluorescence Cell reports Medium 39977269
2017 A missense variant p.Thr270Ala in the DBL homology (DH) domain of ARHGEF18 reduces its ability to interact with and activate RHOA, functionally validating the DH domain as essential for RHOA activation by ARHGEF18. Patient mutation analysis, functional assay testing RHOA interaction/activation by the DH-domain missense variant American journal of human genetics Low 28132693
2025 Arhgef18 associates with the retinal outer limiting membrane (OLM) adherens junctions between Müller glia and photoreceptors; Müller glia-specific knockout causes OLM disruption, retinal rosette formation, progressive degeneration, and vascular leakage. In cultured Müller cells, p114RhoGEF depletion disrupts junctional OLM protein recruitment and activates NF-κB, β-catenin, and TBK1 signaling while reducing mitochondrial activity; TBK1 inhibition or nicotinamide rescues mitochondrial activity and suppresses these signaling pathways. Conditional Müller glia-specific knockout mice, retinal histology and OCT imaging, RNAi knockdown in cultured Müller cells, immunofluorescence for OLM proteins, NF-κB/β-catenin/TBK1 assays, mitochondrial activity measurements, pharmacological rescue bioRxivpreprint Medium

Source papers

Stage 0 corpus · 21 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Spatially restricted activation of RhoA signalling at epithelial junctions by p114RhoGEF drives junction formation and morphogenesis. Nature cell biology 190 21258369
2003 G Protein betagamma subunits stimulate p114RhoGEF, a guanine nucleotide exchange factor for RhoA and Rac1: regulation of cell shape and reactive oxygen species production. Circulation research 101 14512443
2011 Lulu2 regulates the circumferential actomyosin tensile system in epithelial cells through p114RhoGEF. The Journal of cell biology 77 22006950
2013 LKB1 controls human bronchial epithelial morphogenesis through p114RhoGEF-dependent RhoA activation. Molecular and cellular biology 39 23648482
2010 Involvement of p114-RhoGEF and Lfc in Wnt-3a- and dishevelled-induced RhoA activation and neurite retraction in N1E-115 mouse neuroblastoma cells. Molecular biology of the cell 38 20810787
2013 ArhGEF18 regulates RhoA-Rock2 signaling to maintain neuro-epithelial apico-basal polarity and proliferation. Development (Cambridge, England) 34 23698346
2012 Stimulation of cortical myosin phosphorylation by p114RhoGEF drives cell migration and tumor cell invasion. PloS one 30 23185572
2017 Biallelic Mutation of ARHGEF18, Involved in the Determination of Epithelial Apicobasal Polarity, Causes Adult-Onset Retinal Degeneration. American journal of human genetics 25 28132693
2015 p114RhoGEF governs cell motility and lumen formation during tubulogenesis through a ROCK-myosin-II pathway. Journal of cell science 22 26483385
2015 CRB3A Controls the Morphology and Cohesion of Cancer Cells through Ehm2/p114RhoGEF-Dependent Signaling. Molecular and cellular biology 21 26217016
2012 The circumferential actomyosin belt in epithelial cells is regulated by the Lulu2-p114RhoGEF system. Small GTPases 16 22790195
2021 ARHGEF18/p114RhoGEF Coordinates PKA/CREB Signaling and Actomyosin Remodeling to Promote Trophoblast Cell-Cell Fusion During Placenta Morphogenesis. Frontiers in cell and developmental biology 14 33842485
2013 ArhGEF18 regulated Rho signaling in vertebrate retina development. Small GTPases 11 24231347
2016 A Gα12-specific Binding Domain in AKAP-Lbc and p114RhoGEF. Journal of molecular signaling 10 31051012
2018 Association between a Single Nucleotide Polymorphism in the 3'-UTR of ARHGEF18 and the Risk of Nonidiopathic Pulmonary Arterial Hypertension in Chinese Population. Disease markers 8 30405854
2025 SEPTIN9 locally activates the RhoGEF ARHGEF18 to promote early stages of mitochondrial fission. The Journal of cell biology 3 40920138
2023 ARHGEF18 can promote BVDV NS5B activation of the host NF-κB signaling pathway by combining with the NS5B-palm domain. Veterinary microbiology 3 38367539
2018 Expression of novel "LOCGEF" isoforms of ARHGEF18 in eosinophils. Journal of leukocyte biology 3 29601110
2025 ARHGEF18 is a flow-responsive exchange factor controlling endothelial tight junctions and vascular leakage. Cell reports 2 39977269
2023 Establishment and identification of cardiomyocyte arhGEF18 gene conditional knockout mice. Pediatric discovery 1 40625715
2025 Establishment and functional studies of a model of cardiomyopathy with cardiomyocyte-specific conditional knockout of Arhgef18. Disease models & mechanisms 0 40159883

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