Affinage

EFNA4

Ephrin-A4 · UniProt P52798

Length
201 aa
Mass
22.4 kDa
Annotated
2026-06-09
12 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 4/5 claims corpus-supported (80%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

EFNA4 is a GPI-anchored member of the ephrin-A family of Eph receptor ligands (PMID:8660976) that functions as a context-dependent driver of cancer cell proliferation, migration, and survival across multiple tumor types (PMID:36077763). As a canonical ligand it binds EPHA2 and promotes its phosphorylation at Ser897, recruiting PIK3R2 and activating GSK3β/β-catenin signaling in a positive feedback loop that drives hepatocellular carcinoma growth (PMID:34484860). EFNA4 acts upstream of the Wnt/β-catenin co-activator PYGO2, which it physically binds and positively regulates to sustain Wnt signaling and oncogenic phenotypes in hepatocellular and gastric carcinoma (PMID:36404439, PMID:38953488); in gemcitabine-resistant pancreatic cancer this β-catenin activation suppresses deoxycytidine kinase and confers drug resistance (PMID:38590861). Independently of Eph receptor binding, EFNA4 directly interacts with SLC7A11 through a defined domain (a.a. 161-201) and recruits the deubiquitinase USP9X to stabilize SLC7A11, suppressing ROS accumulation and ferroptosis (PMID:39656358). Beyond its oncogenic roles, genetic loss of Efna4 in mice increases bone volume and formation while decreasing osteoclast activity, implicating it in skeletal modeling via the ephrin-Eph axis (PMID:33065355).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 1996 Medium

    Established the molecular nature of EFNA4 as a membrane attachment, defining it as a GPI-anchored Eph receptor ligand rather than a transmembrane ligand.

    Evidence cDNA cloning and sequence analysis of LERK-4/EPLG4

    PMID:8660976

    Open questions at the time
    • No receptor binding partner identified in this work
    • No functional or signaling readout established
  2. 2020 Medium

    Answered whether EFNA4 has a physiological in vivo role by showing it regulates bone modeling, balancing osteoblast and osteoclast activity through ephrin-Eph signaling.

    Evidence Efna4 knockout mouse with micro-CT, histomorphometry, and dynamic bone labeling

    PMID:33065355

    Open questions at the time
    • Specific Eph receptor partner in bone not identified
    • Cell-autonomous mechanism in osteoblasts vs osteoclasts not resolved
  3. 2021 Medium

    Defined the canonical signaling mechanism by which EFNA4 drives tumor growth, linking EPHA2 Ser897 phosphorylation to a PIK3R2/GSK3β/β-catenin feedback loop.

    Evidence Co-IP, gain/loss-of-function and phosphorylation assays in HCC in vitro and in vivo

    PMID:34484860

    Open questions at the time
    • Single lab and tumor type
    • Direct enzymatic basis of Ser897 phosphorylation not dissected
  4. 2022 Medium

    Connected EFNA4 to the Wnt/β-catenin pathway through PYGO2 and demonstrated its broad oncogenic phenotype across liver and lung cancers.

    Evidence Co-IP, epistatic PYGO2 rescue, Wnt reporter assays in HCC; overexpression/KO with xenografts in lung adenocarcinoma

    PMID:36077763 PMID:36404439

    Open questions at the time
    • Mechanism by which EFNA4 regulates PYGO2 protein levels unresolved
    • Whether PYGO2 regulation is receptor-dependent unclear
  5. 2024 Medium

    Revealed a receptor-independent function of EFNA4 in suppressing ferroptosis by stabilizing SLC7A11 via USP9X-mediated deubiquitination.

    Evidence Domain-mapping Co-IP, ubiquitination and ROS/GPX4 assays in an Eph receptor knockout background, in vitro and in vivo

    PMID:39656358

    Open questions at the time
    • How a GPI-anchored ligand engages intracellular SLC7A11/USP9X is not mechanistically explained
    • Single lab
  6. 2024 Medium

    Extended the EFNA4/β-catenin axis to chemoresistance, showing it suppresses deoxycytidine kinase to confer gemcitabine resistance in pancreatic cancer.

    Evidence GEM-resistant cell lines, dCK activity assays, β-catenin antagonist rescue, xenografts

    PMID:38590861

    Open questions at the time
    • Direct vs indirect regulation of dCK not distinguished
    • Single lab
  7. 2025 Low

    Implicated EFNA4 in neurodevelopmental axon guidance through PI3K/AKT signaling, though only via indirect pharmacological modulation.

    Evidence BTBR autism model mice with calcitriol treatment, RNA-seq, IHC, stripe guidance assays

    PMID:40395150

    Open questions at the time
    • Pathway link inferred from drug treatment without direct EFNA4 manipulation
    • No demonstration of EFNA4 acting cell-autonomously in neural progenitors

Open questions

Synthesis pass · forward-looking unresolved questions
  • How EFNA4 switches between canonical Eph receptor-dependent signaling and receptor-independent intracellular partner stabilization, and what governs this choice across tissues, remains unresolved.
  • No structural model of EFNA4 signaling states
  • Determinants of context-specific partner selection (EPHA2 vs SLC7A11 vs PYGO2) unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0048018 receptor ligand activity 2 GO:0098772 molecular function regulator activity 2
Localization
GO:0005886 plasma membrane 1
Pathway
R-HSA-162582 Signal Transduction 3 R-HSA-1643685 Disease 2 R-HSA-5357801 Programmed Cell Death 1
Partners
EPHA2PIK3R2PYGO2SLC7A11USP9X

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1996 EFNA4 (LERK-4/EPLG4) is anchored to the cell membrane via glycosyl-phosphatidylinositol (GPI) linkage, placing it in the GPI-anchored subgroup of Eph receptor ligands (LERKs), distinct from the type-1 transmembrane subgroup. cDNA cloning and sequence analysis identifying GPI-anchored membrane attachment Genomics Medium 8660976
2021 EFNA4 directly interacts with EPHA2 and promotes its phosphorylation at Ser897, leading to recruitment of PIK3R2 and activation of the GSK3β/β-catenin signaling pathway, which in turn promotes PIK3R2 expression forming a positive feedback loop that drives HCC cell proliferation and migration. Co-immunoprecipitation, overexpression and knockdown experiments in vitro and in vivo, phosphorylation assays Molecular therapy. Nucleic acids Medium 34484860
2022 EFNA4 interacts with PYGO2 and positively regulates PYGO2 expression; EFNA4 knockdown suppresses Wnt/β-catenin signaling in HCC cells, and this effect is rescued by PYGO2 overexpression, placing EFNA4 upstream of PYGO2 in Wnt/β-catenin pathway regulation. Co-immunoprecipitation, gain- and loss-of-function experiments, Wnt signaling reporter assays, rescue experiments Cancer biology & therapy Medium 36404439
2022 EFNA4 overexpression contributes to lung tumor cell growth, migration, and adhesion, while EFNA4 knockdown or knockout suppresses cell growth and xenograft tumor growth in mice, demonstrating a functional oncogenic role in lung adenocarcinoma. EFNA4 overexpression and knockdown/knockout in cell lines, xenograft tumor models in mice Cancers Medium 36077763
2024 EFNA4 inhibits ferroptosis in HCC independently of Eph receptor binding by directly interacting with SLC7A11 through its domain (a.a. 161-201) binding to SLC7A11 domain (a.a. 222-501), recruiting the deubiquitinase USP9X, and thereby stabilizing SLC7A11 through deubiquitination, which suppresses reactive oxygen species accumulation and ferroptosis. CRISPR/Cas9 Eph receptor knockout environment, domain mapping by co-immunoprecipitation, ubiquitination assays, apoptosis/ROS/GPX4 assays, in vitro and in vivo experiments Apoptosis : an international journal on programmed cell death Medium 39656358
2024 EFNA4 activates β-catenin signaling and suppresses deoxycytidine kinase (dCK) expression in gemcitabine-resistant pancreatic cancer cells; hyperthermia reduces EFNA4 expression, which leads to decreased β-catenin activation and restored dCK activity, sensitizing cells to gemcitabine. β-catenin antagonist MSAB rescues the effect of EFNA4 overexpression on dCK suppression. GEM-resistant cell line engineering, MTT assay, dCK activity assay, lentiviral dCK silencing, EFNA4 overexpression with β-catenin antagonist rescue, xenograft tumor models Heliyon Medium 38590861
2024 EFNA4 knockdown in gastric cancer cells reduces PYGO2 protein expression and inactivates Wnt/β-catenin signaling; overexpression of PYGO2 reverses the effects of EFNA4 silencing on Wnt/β-catenin signaling, proliferation, apoptosis, migration, invasion, angiogenesis, and stemness, placing EFNA4 upstream of PYGO2/Wnt signaling in gastric cancer. siRNA knockdown, western blot, CCK-8/EDU proliferation, Transwell invasion, tube formation, sphere formation, rescue experiments with PYGO2 overexpression Histology and histopathology Medium 38953488
2020 Efna4 knockout mice exhibit increased bone volume/trabecular volume (BV/TV) in the femur, increased bone formation rate, increased osteoblast labeling surfaces, and decreased osteoclast activity, demonstrating that EFNA4 plays a functional role in regulating bone modeling through the Ephrin-Eph receptor signaling axis between osteoblasts and osteoclasts. Efna4 knockout mouse, micro-CT, cryohistomorphometry, dynamic bone labeling, cellular histomorphometric analysis Bone Medium 33065355
2025 Calcitriol supplementation in BTBR autism model mice corrects axon guidance abnormalities and hippocampal hypoplasia; these effects are mediated through modulation of the EfnA4-PI3K/AKT signaling pathway in hippocampal neural progenitor cells, placing EFNA4 in the PI3K/AKT pathway controlling axon guidance in neurodevelopment. BTBR mouse model, behavioral assessments, RNA sequencing, immunohistochemistry, biochemical assays, stripe guidance assays CNS neuroscience & therapeutics Low 40395150

Source papers

Stage 0 corpus · 12 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2015 Anti-EFNA4 Calicheamicin Conjugates Effectively Target Triple-Negative Breast and Ovarian Tumor-Initiating Cells to Result in Sustained Tumor Regressions. Clinical cancer research : an official journal of the American Association for Cancer Research 65 26015513
2019 First-in-human, phase I study of PF-06647263, an anti-EFNA4 calicheamicin antibody-drug conjugate, in patients with advanced solid tumors. International journal of cancer 35 30680712
2021 EFNA4 promotes cell proliferation and tumor metastasis in hepatocellular carcinoma through a PIK3R2/GSK3β/β-catenin positive feedback loop. Molecular therapy. Nucleic acids 24 34484860
1996 The genes encoding the eph-related receptor tyrosine kinase ligands LERK-1 (EPLG1, Epl1), LERK-3 (EPLG3, Epl3), and LERK-4 (EPLG4, Epl4) are clustered on human chromosome 1 and mouse chromosome 3. Genomics 13 8660976
2022 Oncogenic EFNA4 Amplification Promotes Lung Adenocarcinoma Lymph Node Metastasis. Cancers 10 36077763
2022 Interference of EFNA4 suppresses cell proliferation, invasion and angiogenesis in hepatocellular carcinoma by downregulating PYGO2. Cancer biology & therapy 10 36404439
2025 Calcitriol Modulates Hippocampal Axon Guidance Through Enhanced EfnA4-Mediated PI3K/AKT Signaling in an Autism Mouse Model. CNS neuroscience & therapeutics 4 40395150
2024 Hyperthermia improves gemcitabine sensitivity of pancreatic cancer cells by suppressing the EFNA4/β-catenin axis and activating dCK. Heliyon 4 38590861
2024 EFNA4-enhanced deubiquitination of SLC7A11 inhibits ferroptosis in hepatocellular carcinoma. Apoptosis : an international journal on programmed cell death 4 39656358
2022 TBX3 and EFNA4 Variant in a Family with Ulnar-Mammary Syndrome and Sagittal Craniosynostosis. Genes 4 36140816
2024 EFNA4 deletion suppresses the migration, invasion, stemness, and angiogenesis of gastric cancer cells through the inactivation of Pygo2/Wnt signaling. Histology and histopathology 3 38953488
2020 Skeletal screening IMPC/KOMP using μCT and computer automated cryohistology: Application to the Efna4 KO mouse line. Bone 3 33065355

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