Affinage

GAB3

GRB2-associated-binding protein 3 · UniProt Q8WWW8

Length
586 aa
Mass
65.6 kDa
Annotated
2026-06-09
12 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GAB3 is a tyrosine-phosphorylated scaffolding/docking protein that couples cytokine and growth factor receptors to MAPK (ERK) and PI3K/Akt signaling (PMID:11739737, PMID:31375526, PMID:28115166). Containing an N-terminal PH domain, multiple tyrosine phosphorylation sites, and polyproline motifs, GAB3 is phosphorylated downstream of the M-CSF receptor and recruits the SH2 domain-containing effectors p85 (PI3K regulatory subunit) and SHP2, as well as the adapter Mona/Gads, with its phosphorylation and adapter binding driving macrophage differentiation (PMID:11739737, PMID:11997510). In the immune system GAB3 selectively transmits MAPK but not STAT5 signals downstream of IL-2 and IL-15 receptors, an activity required for NK cell priming and expansion, anti-tumor and 'missing-self' clearance, and uterine NK-dependent spiral artery remodeling during pregnancy (PMID:31375526); together with the paralog GAB2 it sustains PI3K/Akt/mTORC1 signaling in macrophages and T cells to suppress colitis (PMID:30936879). In cancer cells, GAB3 acts bidirectionally: it associates with p85 and SHP2 to promote Akt/Erk activation and proliferation in colorectal and glioma cells (PMID:28115166, PMID:28291820), yet binds LYN kinase in lung adenocarcinoma to inhibit MAPK signaling, reverse EMT, and remodel the tumor immune microenvironment (PMID:42031161). GAB3 also docks RSK kinases via a DDVF-like short linear motif, positioning it upstream of RSK in the RAS-ERK pathway [PMID:bio_10.1101_2024.08.08.607128]. Despite intact development in Gab3-deficient mice, these data establish GAB3 as a context-dependent node integrating receptor-proximal kinase signaling (PMID:12640125, PMID:31375526).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2002 Medium

    Established GAB3 as a phosphotyrosine docking protein in receptor signaling by showing it is tyrosine-phosphorylated downstream of the M-CSF receptor and assembles p85/PI3K and SHP2, linking it to macrophage differentiation.

    Evidence Co-immunoprecipitation and overexpression with M-CSF stimulation in FD-Fms myeloid cells, with mutant receptor lines

    PMID:11739737

    Open questions at the time
    • Domain requirements for p85/SHP2 binding not mapped on GAB3
    • Endogenous (non-overexpression) contribution to differentiation unresolved
  2. 2002 High

    Resolved which adapters GAB3 engages, distinguishing it from GAB2 by demonstrating a direct Mona/Gads SH3 to GAB3 proline-rich domain interaction during myeloid differentiation.

    Evidence GST pull-down with domain-level resolution plus mutant M-CSF receptor lines and co-IP

    PMID:11997510

    Open questions at the time
    • Functional consequence of the Mona/Gads interaction for downstream signaling not isolated
    • Relative contributions of Grb2 vs Mona binding unclear
  3. 2003 High

    Tested GAB3's necessity in vivo and found it dispensable for steady-state hematopoiesis and standard immune responses, indicating its role is restricted or redundant rather than constitutive.

    Evidence Homologous-recombination Gab3-/- mice with functional immune assays and flow cytometry

    PMID:12640125

    Open questions at the time
    • Did not probe specific cytokine contexts (IL-2/IL-15, NK biology) later found to require GAB3
    • No transcriptional compensation by Gab1/Gab2 examined as the sole explanation
  4. 2019 High

    Defined a selective signaling function by showing GAB3 channels MAPK but not STAT5 output from IL-2/IL-15 receptors, making it essential for NK cell expansion, tumor clearance, and uterine NK-mediated placental remodeling.

    Evidence Gab3-/- mice with MAPK vs STAT5 phosphorylation dissection, in vivo tumor challenge, and placental histology

    PMID:31375526

    Open questions at the time
    • Molecular basis for MAPK-selective (STAT5-sparing) coupling not defined
    • Receptor-proximal partners in NK cells not identified
  5. 2019 Medium

    Revealed paralog redundancy and a PI3K/Akt/mTORC1 axis by showing only Gab2/Gab3 double knockout causes hematopoietic-cell-intrinsic colitis.

    Evidence Double-knockout mice with reciprocal bone marrow transplantation and PI3K/Akt/mTORC1 and STAT5 readouts

    PMID:30936879

    Open questions at the time
    • GAB3-specific (vs GAB2) contribution not separable
    • Direct molecular link from GAB2/3 to mTORC1 activation not established
  6. 2017 Medium

    Extended GAB3 signaling to cancer, showing p85/SHP2 association drives Akt/Erk activation and proliferation in colorectal and glioma cells.

    Evidence Co-IP, bidirectional knockdown/overexpression with Akt/Erk readouts, and xenograft models

    PMID:28115166 PMID:28291820

    Open questions at the time
    • Upstream receptor driving GAB3 phosphorylation in tumor cells not identified
    • Glioma study identified no binding partner
  7. 2024 Low

    Identified GAB3 as an RSK-binding protein via a DDVF-like short linear motif, placing it within RAS-ERK pathway feedback architecture.

    Evidence Co-immunoprecipitation with AlphaFold/SLiM prediction and RSK docking-site mutant analysis (preprint)

    PMID:bio_10.1101_2024.08.08.607128

    Open questions at the time
    • Single Co-IP without mutagenesis of GAB3's SLiM
    • Functional consequence of GAB3-RSK binding not demonstrated
    • Preprint, not peer-reviewed
  8. 2026 Medium

    Uncovered a context-dependent tumor-suppressive role by showing GAB3 binds LYN to inhibit MAPK, reverse EMT, and enhance anti-tumor immunity in lung adenocarcinoma.

    Evidence Co-IP of GAB3-LYN, overexpression/knockdown with MAPK/EMT readouts, in vivo tumor models and immune profiling

    PMID:42031161

    Open questions at the time
    • Mechanism reconciling MAPK-suppressive (LUAD) vs MAPK-promoting (CRC/glioma) roles unresolved
    • Direct linkage from GAB3-LYN to CXCL10 induction not mapped

Open questions

Synthesis pass · forward-looking unresolved questions
  • How GAB3 selects between opposing outputs — MAPK-promoting versus MAPK-suppressing, and PI3K/Akt versus STAT5 — across cell types remains the central open question.
  • No structural model of GAB3 effector assembly
  • Determinants of partner choice (p85/SHP2 vs LYN vs RSK) by cellular context unknown
  • Mechanism of STAT5-sparing MAPK selectivity undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3
Pathway
R-HSA-162582 Signal Transduction 3 R-HSA-168256 Immune System 3

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 Gab3 contains an amino-terminal pleckstrin homology (PH) domain, multiple tyrosine phosphorylation sites, and polyproline motifs. After M-CSF receptor (Fms) stimulation, Gab3 is tyrosine phosphorylated and transiently associates with the SH2 domain-containing proteins p85 (PI3K regulatory subunit) and SHP2. Overexpression of Gab3 in FD-Fms cells dramatically accelerates macrophage differentiation upon M-CSF stimulation, and differentiation requires early phosphorylation of Gab2 followed by induction and phosphorylation of Gab3. Co-immunoprecipitation, overexpression in FDC-P1/FD-Fms cell lines, mRNA expression analysis, M-CSF stimulation assays, mutant receptor lines (Y807F, Y807F) Molecular and cellular biology Medium 11739737
2002 Gab3 interacts specifically with the adapter protein Mona/Gads (but not with the related adapter Grb2 in the same context distinguishing it from Gab2) during monocyte/macrophage differentiation. GST pull-down experiments demonstrated that this interaction requires the carboxy-terminal SH3 domain of Mona and the atypical proline-rich domain of Gab3. Gab3 also forms a complex with the Mona-related adapter Grb2. The M-CSFR Y697F mutation reduced Gab3 tyrosine phosphorylation and Mona induction, while Y807F (differentiation-defective) also failed to induce Mona expression. GST pull-down, co-immunoprecipitation, mutant M-CSF receptor lines (Y697F, Y807F), immunoblotting during bone marrow macrophage differentiation Molecular and cellular biology High 11997510
2003 Gab3-deficient (Gab3-/-) mice develop normally with intact hematopoiesis: macrophages develop in normal numbers and exhibit normal function; T- and B-lymphocyte responses to protein antigens, viral infection, and allergic responses are unimpaired. Loss of Gab3 is not compensated by increased Gab1 or Gab2 mRNA levels. Homologous recombination knockout, generation of Gab3-specific monoclonal antibodies, immunoblotting, flow cytometry, functional immune assays Molecular and cellular biology High 12640125
2019 Gab3 is required for IL-2- and IL-15-induced NK cell priming and expansion. Loss of Gab3 selectively impairs MAPK signaling (ERK activation) downstream of cytokine receptors but does not affect STAT5 signaling. In vivo, Gab3-deficient mice show impaired elimination of 'missing-self' and tumor targets. Additionally, Gab3 is required for uterine NK cell expansion; its absence causes abnormal spiral artery remodeling, increased trophoblast invasion, and pregnancy complications. Gab3-/- mouse model, cytokine stimulation assays, MAPK and STAT5 phosphorylation analysis (signaling pathway dissection), in vivo tumor challenge, NK cell functional assays, histological analysis of placenta Science immunology High 31375526
2019 Gab2 and Gab3 redundantly suppress colitis by modulating macrophage and CD8+ T-cell activation. Gab2/3 double knockout (but not single knockouts) develop spontaneous colitis. Reciprocal bone marrow transplantation established that the disease-initiating process is hematopoietic cell-intrinsic. Mechanistically, loss of Gab2/3 reduces PI3-kinase/Akt/mTORC1 signaling in macrophages and T-cells, while IL-2-stimulated T-cells show increased pSTAT5. Double-knockout mouse generation, reciprocal bone marrow transplantation, adoptive transfer, PI3K/Akt/mTORC1 and STAT5 phosphorylation analysis Frontiers in immunology Medium 30936879
2017 In colorectal cancer cells, Gab3 co-precipitates with p85 (PI3K regulatory subunit) and SHP2, and this association is required for subsequent Akt and Erk activation. Gab3 knockdown inhibits Akt and Erk activation, while Gab3 overexpression augments it, promoting CRC cell proliferation. Co-immunoprecipitation, shRNA/siRNA knockdown, overexpression, Akt and Erk phosphorylation analysis, xenograft tumor model Biochemical and biophysical research communications Medium 28115166
2017 In glioma cells, Gab3 knockdown (shRNA/siRNA) significantly inhibits Akt activation and cell proliferation, while forced Gab3 overexpression promotes Akt activation and cell proliferation. In vivo xenograft tumor growth is inhibited by Gab3 shRNA with corresponding suppression of Akt activation. shRNA/siRNA knockdown, overexpression, Akt phosphorylation analysis, xenograft tumor model in nude mice PloS one Medium 28291820
2024 GAB3 interacts with RSK kinases (p90 ribosomal S6 kinases) through a DDVF-like short linear motif (SLiM), using the same docking interface exploited by viral and bacterial pathogen proteins. Co-immunoprecipitation confirmed that GAB3 is a novel RSK-binding partner. GAB3 and other DDVF-like SLiM-containing proteins act upstream of RSK in the RAS-ERK MAPK pathway, and RSK's DDVF-docking site may provide negative feedback to ERK MAPK signaling. Co-immunoprecipitation, AlphaFold docking/SLiM prediction, analysis of RSK mutant lacking DDVF-docking site for ERK activation bioRxiv (preprint)preprint Low bio_10.1101_2024.08.08.607128
2026 GAB3 interacts with LYN kinase in lung adenocarcinoma cells to inhibit the MAPK signaling pathway and reverse epithelial-mesenchymal transition (EMT). GAB3 overexpression suppresses LUAD cell proliferation, migration, invasion, and tumor growth. GAB3 also remodels the tumor immune microenvironment by enhancing CXCL10 secretion, increasing CD8+ T cell infiltration and effector function, and sensitizing tumors to anti-PD-1 therapy. Co-immunoprecipitation (GAB3-LYN interaction), overexpression and knockdown with MAPK/EMT readouts, in vivo tumor models, immune profiling Cancer letters Medium 42031161

Source papers

Stage 0 corpus · 12 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 Gab3, a new DOS/Gab family member, facilitates macrophage differentiation. Molecular and cellular biology 71 11739737
2019 Gab3 is required for IL-2- and IL-15-induced NK cell expansion and limits trophoblast invasion during pregnancy. Science immunology 54 31375526
2003 Gab3-deficient mice exhibit normal development and hematopoiesis and are immunocompetent. Molecular and cellular biology 45 12640125
2002 Induced expression and association of the Mona/Gads adapter and Gab3 scaffolding protein during monocyte/macrophage differentiation. Molecular and cellular biology 34 11997510
2019 Gab2 and Gab3 Redundantly Suppress Colitis by Modulating Macrophage and CD8+ T-Cell Activation. Frontiers in immunology 16 30936879
2017 Gab3 overexpression in human glioma mediates Akt activation and tumor cell proliferation. PloS one 13 28291820
2017 Gab3 is required for human colorectal cancer cell proliferation. Biochemical and biophysical research communications 12 28115166
2022 Silencing Asian Seabass gab3 Inhibits Nervous Necrosis Virus Replication. Marine biotechnology (New York, N.Y.) 6 36227511
2020 Characterization of GAB3 and its association with NNV resistance in the Asian seabass. Fish & shellfish immunology 6 32473363
2024 Association analysis of polymorphisms in SLK, ARHGEF9, WWC2, GAB3, and FSHR genes with reproductive traits in different sheep breeds. Frontiers in genetics 5 38680425
2026 GAB3 suppresses lung adenocarcinoma progression by inhibiting the MAPK signaling and potentiating CD8+ T cell immunity. Cancer letters 0 42031161
2025 Genetic susceptibility to essential hypertension in the Chinese han population: a study on GAB1, GAB2, and GAB3 gene polymorphisms. BMC cardiovascular disorders 0 40140746

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