Affinage

ARHGAP15

Rho GTPase-activating protein 15 · UniProt Q53QZ3

Length
475 aa
Mass
54.5 kDa
Annotated
2026-06-09
12 papers in source corpus 9 papers cited in narrative 9 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

ARHGAP15 is a Rac1-specific GTPase-activating protein that acts as a dual negative regulator of Rac1 signaling and thereby controls cell motility, proliferation, and circuit assembly (PMID:12650940, PMID:23760270). It is organized into a PH domain required for membrane/cell-periphery localization, a RhoGAP catalytic domain specific for Rac1 in vitro, and a novel N-terminal motif that mediates nucleotide-independent binding to the C-terminal half of Rac1; full-length expression promotes actin stress fibers and cell contraction in a Rac1-dependent manner (PMID:12650940). Beyond accelerating Rac1 GTP hydrolysis, ARHGAP15 binds Pak1/2 through its PH domain to produce mutual inhibition — its own GAP activity is suppressed while it blocks Pak1/2 kinase activity — and it is itself a Pak1/2 substrate, so its loss activates Pak1/2 both indirectly via Rac and directly by disrupting the complex (PMID:23760270). In vivo, loss of ArhGAP15 hyperactivates Rac1/Rac3 and impairs the migration of inhibitory interneurons into the hippocampus, altering excitatory/inhibitory synaptic balance and producing memory deficits (PMID:27713499). Across multiple epithelial cancers ARHGAP15 behaves as a tumor suppressor by dampening Rac1 activity, restraining proliferation, migration, and invasion through downstream PTEN/AKT/FOXO1 (PMID:29867200), STAT3 (PMID:31298335), and ROS (PMID:36802400) effector arms, with its expression transcriptionally controlled by FOXP3 (PMID:27862679), FOXO1 feedback (PMID:29867200), and androgens (PMID:29534468).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2003 High

    Established ARHGAP15 as a Rac1-directed RhoGAP and defined its domain logic, answering what GTPase it regulates and which domains drive binding and localization.

    Evidence In vitro GAP assay, Rac/Cdc42 swop mutants, domain-deletion overexpression, and dominant-negative Rac1 co-expression with cell morphology readouts

    PMID:12650940

    Open questions at the time
    • In vitro Rac1 specificity not tested against the full Rho GTPase panel in cells
    • Function of the novel N-terminal nucleotide-independent binding motif beyond Rac1 capture unresolved
    • Structural basis of PH-domain membrane targeting not determined
  2. 2013 High

    Revealed a second regulatory layer beyond GAP activity by showing ARHGAP15 and Pak1/2 form a mutually inhibitory complex, explaining how ARHGAP15 doubly suppresses Rac effector output.

    Evidence Protein microarray screen, co-immunoprecipitation, reciprocal kinase and GAP activity assays, and siRNA knockdown

    PMID:23760270

    Open questions at the time
    • Phosphosites on ARHGAP15 targeted by Pak1/2 and their functional consequence not mapped
    • Stoichiometry and structural interface of the PH-domain/Pak association unknown
    • Physiological contexts where the complex predominates over GAP activity not defined
  3. 2013 Low

    Linked ARHGAP15 to apoptotic sensitivity by showing its knockdown protects against ethanol-induced cell death, raising a possible role in stress-induced apoptosis.

    Evidence siRNA knockdown with Bax/Bcl-2 and caspase-3 readouts and viability assay in ethanol-treated bovine fibroblasts

    PMID:23625437

    Open questions at the time
    • Single-method knockdown with no rescue and no link to GAP activity
    • Mechanism connecting ARHGAP15 to apoptotic machinery undefined
    • Not confirmed in mammalian or human cells
  4. 2016 High

    Demonstrated the physiological requirement for ArhGAP15 in restraining Rac1/Rac3 during neurodevelopment, connecting GAP activity to interneuron migration and circuit function.

    Evidence ArhGAP15 knockout mouse with Rac activity assays, interneuron migration analysis, electrophysiology, and behavioral testing

    PMID:27713499

    Open questions at the time
    • Cell-autonomous versus circuit-level contributions to migration not separated
    • Role of Pak inhibition versus Rac GAP activity in the neuronal phenotype unresolved
    • Selectivity for interneurons over pyramidal neurons unexplained mechanistically
  5. 2017 Medium

    Identified FOXP3 as an upstream transcriptional activator of ARHGAP15, placing the GAP in a FOXP3-Rac1-migration axis in glioma.

    Evidence DNA microarray, qRT-PCR, Western blot, IHC, and overexpression/knockdown migration assays in glioma cells

    PMID:27862679

    Open questions at the time
    • No direct promoter binding or ChIP evidence reported
    • Whether regulation is direct or indirect unresolved
    • Generalizability beyond glioma not tested
  6. 2018 Medium

    Wired ARHGAP15 into a PTEN/AKT/FOXO1 tumor-suppressive circuit with a feed-forward loop, explaining how it arrests cell cycle and limits metastasis in colorectal cancer.

    Evidence Overexpression/knockdown in CRC lines, luciferase promoter assay, GSEA, pharmacological AKT inhibition, and xenograft/metastasis models

    PMID:29867200

    Open questions at the time
    • Direct FOXO1 binding to the ARHGAP15 promoter not shown
    • How Rac1 inactivation feeds into PTEN signaling mechanistically undefined
    • Single-lab pathway placement
  7. 2018 Medium

    Established ARHGAP15 as an androgen-regulated, growth-suppressive gene in breast cancer, adding hormonal control to its transcriptional regulation.

    Evidence Overexpression and dihydrotestosterone treatment in breast cancer lines with proliferation/migration assays and tissue IHC correlation

    PMID:29534468

    Open questions at the time
    • Direct androgen-receptor binding to the ARHGAP15 locus not demonstrated
    • Mechanism coupling AR signaling to ARHGAP15 induction unknown
    • Functional consequence of AR/Rac1/ARHGAP15 co-expression in vivo not tested
  8. 2019 Medium

    Positioned ARHGAP15 upstream of STAT3 in lung cancer, broadening its tumor-suppressive output to an IL-6/STAT3 invasion axis.

    Evidence Overexpression/knockdown, transwell assays, Western blot, and STAT3 inhibitor (AG490) epistasis in lung cancer cells

    PMID:31298335

    Open questions at the time
    • Mechanistic link from Rac1 inactivation to STAT3 dephosphorylation not defined
    • Pharmacological epistasis only, no genetic STAT3 manipulation
    • Single-lab study
  9. 2023 High

    Uncovered a redox dimension showing ARHGAP15 lowers RAC1-driven ROS to enhance cancer cell survival during metastatic colonization, refining its context-dependent role.

    Evidence Ectopic expression/knockdown, in vivo colonization assay, ROS measurement, and constitutively active RAC1 rescue in gastric cancer

    PMID:36802400

    Open questions at the time
    • Source of Rac1-dependent ROS in this setting not identified
    • Reconciliation of pro-survival colonization role with tumor-suppressor role in other cancers incomplete
    • Downstream antioxidant effectors not mapped

Open questions

Synthesis pass · forward-looking unresolved questions
  • How ARHGAP15's two negative functions — Rac1 GAP activity and Pak1/2 sequestration — are balanced and switched across neuronal, epithelial, and metastatic contexts remains unresolved.
  • No structural model of the autoinhibitory ARHGAP15/Pak complex or PH-domain membrane engagement
  • Phosphoregulation by Pak1/2 not functionally mapped
  • Context-dependent tumor-suppressor versus pro-survival switch mechanistically unexplained

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 3 GO:0140096 catalytic activity, acting on a protein 1
Localization
GO:0005886 plasma membrane 1
Pathway
R-HSA-1643685 Disease 3 R-HSA-162582 Signal Transduction 2 R-HSA-1266738 Developmental Biology 1
Partners

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2003 ARHGAP15 contains a pleckstrin homology (PH) domain, a RhoGAP domain, and a novel motif N-terminal to the GAP domain. The novel motif mediates nucleotide-independent Rac1 binding through the C-terminal half of Rac1 (established by swop mutants of Rac/Cdc42). The GAP domain shows specificity towards Rac1 in vitro. The PH domain is required for membrane/cell-periphery localization. Overexpression of full-length ARHGAP15 (but not PH-domain deletion mutant) increases actin stress fibers and cell contraction, effects attenuated by co-expression of dominant-negative Rac1(N17). ARHGAP15-expressing HeLa cells are resistant to phorbol myristate acetate treatment. In vitro GAP activity assay, Rac/Cdc42 swop mutants, overexpression/deletion constructs, co-expression with dominant-negative Rac1, cell morphology analysis, PMA treatment assay FEBS letters High 12650940
2013 ARHGAP15 serves as a substrate of Rac effectors Pak1 and Pak2 (identified by protein microarray screen). ARHGAP15 also binds Pak1/2 via its PH domain. The ArhGAP15–Pak1/2 association results in mutual inhibition: ARHGAP15 GAP activity is inhibited and Pak1/2 kinase activity is inhibited. Knockdown of ARHGAP15 activates Pak1/2 both indirectly (through Rac activation) and directly (by disrupting the ARHGAP15/Pak complex), indicating a dual negative regulatory role. Protein microarray screen, co-immunoprecipitation, kinase activity assay, GAP activity assay, siRNA knockdown The Journal of biological chemistry High 23760270
2016 Loss of ArhGAP15 in mice results in hyperactivation of Rac1/Rac3. In the hippocampus, ArhGAP15 knockout reduces the number of CR+, PV+, and SST+ inhibitory interneurons in CA3 and dentate gyrus due to reduced efficiency and directionality of their migration (pyramidal neurons are unaffected). Loss of ArhGAP15 alters neuritogenesis and the balance between excitatory and inhibitory synapses, resulting in increased spike frequency and bursts with poor synchronization. Adult ArhGAP15-/- mice show defective hippocampus-dependent working and associative memory. ArhGAP15 knockout mouse model, Rac1/Rac3 activity assays, interneuron counting and migration analysis, electrophysiology, behavioral testing Scientific reports High 27713499
2017 FOXP3 transcriptionally regulates ARHGAP15 expression. Overexpression of FOXP3 upregulates ARHGAP15, which inactivates Rac1, inhibiting glioma cell migration. Silencing FOXP3 downregulates ARHGAP15 and activates Rac1, promoting migration. FOXP3 also regulates EMT markers E-cadherin and N-cadherin in this context. DNA microarray, qRT-PCR, Western blot, immunohistochemistry, overexpression and siRNA knockdown in glioma cells, migration assays Cancer science Medium 27862679
2018 In colorectal cancer cells, ARHGAP15 overexpression activates PTEN signaling, increases FOXO1 activity, and decreases AKT phosphorylation. This leads to increased p21 (causing S-phase arrest), decreased MMP-2 and MMP-9 (reducing metastasis). Conversely, FOXO1 overexpression enhances ARHGAP15 expression and promoter activity, indicating a regulatory feedback loop. PTEN upregulation, FOXO1 overexpression, or AKT inhibition (MK2206) suppressed proliferation and metastasis in ARHGAP15-silenced cells. Overexpression and siRNA knockdown in CRC cell lines, Western blot, GSEA, luciferase promoter assay, in vivo xenograft/lung metastasis model, pharmacological AKT inhibition Cell death & disease Medium 29867200
2018 ARHGAP15 overexpression suppresses cell proliferation and migration of breast cancer cell lines (MCF-7 and SK-BR-3). ARHGAP15 mRNA is induced by dihydrotestosterone, identifying it as an androgen-regulated gene, and its protein immunoreactivity positively correlates with Rac1 and androgen receptor expression in breast carcinoma tissues. Overexpression in breast cancer cell lines, proliferation and migration assays, dihydrotestosterone treatment, immunohistochemistry International journal of molecular sciences Medium 29534468
2019 ARHGAP15 overexpression in lung cancer cells suppresses cell proliferation, migration, and invasion and reduces MMP-2, MMP-9, VEGF expression and STAT3 phosphorylation (p-STAT3). IL-6-induced proliferation and invasion are counteracted by ARHGAP15 upregulation. ARHGAP15 silencing-induced effects are inhibited by the STAT3 inhibitor AG490, placing ARHGAP15 upstream of STAT3 in this pathway. Overexpression and siRNA knockdown in lung cancer cell lines, proliferation/transwell assays, Western blot, pharmacological STAT3 inhibition (AG490) European review for medical and pharmacological sciences Medium 31298335
2023 ARHGAP15 inactivates RAC1, thereby decreasing intracellular reactive oxygen species (ROS) accumulation, which enhances the antioxidant capacity and survival of gastric cancer cells under oxidative stress during metastatic colonization. This pro-colonization phenotype is phenocopied by RAC1 inhibition and rescued by constitutively active RAC1, placing ARHGAP15 upstream of RAC1 in the ROS-regulation pathway. Ectopic expression and genetic knockdown in gastric cancer cells, in vivo lung/lymph node colonization assay in mice, ROS measurement, RAC1 inhibition and constitutively active RAC1 rescue experiments PLoS genetics High 36802400
2013 siRNA knockdown of ARHGAP15 in bovine fibroblast cells decreases the Bax/Bcl-2 ratio and caspase-3 levels in ethanol-treated cells, suggesting that ARHGAP15 activity is required for ethanol-induced apoptosis. Loss of ARHGAP15 is protective against ethanol-induced cell death. siRNA knockdown, RT-PCR, Western blot for Bax, Bcl-2, caspase-3, cell viability assay in ethanol-treated bovine fibroblasts Pakistan journal of pharmaceutical sciences Low 23625437

Source papers

Stage 0 corpus · 12 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 Sequence variants in ARHGAP15, COLQ and FAM155A associate with diverticular disease and diverticulitis. Nature communications 69 28585551
2003 ArhGAP15, a novel human RacGAP protein with GTPase binding property. FEBS letters 59 12650940
2018 Decreased expression of ARHGAP15 promotes the development of colorectal cancer through PTEN/AKT/FOXO1 axis. Cell death & disease 32 29867200
2016 Disruption of ArhGAP15 results in hyperactive Rac1, affects the architecture and function of hippocampal inhibitory neurons and causes cognitive deficits. Scientific reports 31 27713499
2018 ARHGAP15 in Human Breast Carcinoma: A Potent Tumor Suppressor Regulated by Androgens. International journal of molecular sciences 26 29534468
2013 ArhGAP15, a Rac-specific GTPase-activating protein, plays a dual role in inhibiting small GTPase signaling. The Journal of biological chemistry 24 23760270
2017 Forkhead box P3 regulates ARHGAP15 expression and affects migration of glioma cells through the Rac1 signaling pathway. Cancer science 21 27862679
2019 ARHGAP15 regulates lung cancer cell proliferation and metastasis via the STAT3 pathway. European review for medical and pharmacological sciences 11 31298335
2023 ARHGAP15 promotes metastatic colonization in gastric cancer by suppressing RAC1-ROS pathway. PLoS genetics 9 36802400
2016 African Cattle do not Carry Unique Mutations on the Exon 9 of the ARHGAP15 Gene. Animal biotechnology 8 26515718
2021 COLQ and ARHGAP15 are Associated with Diverticular Disease and are Expressed in the Colon. The Journal of surgical research 6 34225052
2013 Rho GTPase activating protein 15 (arhGAP15) siRNA effect apoptosis-induced by ethanol in bovine fibroblast cells. Pakistan journal of pharmaceutical sciences 5 23625437

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