EYA3

EYA3 is a multifunctional transcriptional co-activator and phosphatase that integrates developmental gene regulation, DNA damage repair, cytoskeletal remodeling, and immune evasion. As a transcriptional co-activator, EYA3 partners with SIX-family homeoproteins (SIX1, SIX4, SIX5), SKI, and p300 to drive expression of genes controlling myogenesis, photoperiodic signaling, and tumor-promoting programs such as VEGFA and EGFR; alternatively spliced isoforms regulated by RBFOX2 confer partner selectivity and distinct transcriptional outputs during myogenic differentiation (PMID:19008232, PMID:21129973, PMID:35957720, PMID:38026174). Its C-terminal HAD-family tyrosine phosphatase domain dephosphorylates H2AX-pY142 to promote DNA damage repair and cell survival—a function exploited in Ewing sarcoma chemoresistance and pulmonary vascular remodeling—and dephosphorylates WDR1-pY to reorganize the actin cytoskeleton (PMID:22723308, PMID:29440662, PMID:31515519, PMID:33649104). The N-terminal domain lacks intrinsic Ser/Thr phosphatase activity but instead recruits PP2A-B55α holoenzyme through a conserved peptide motif that binds the B55α substrate-recruitment surface, redirecting PP2A to dephosphorylate c-Myc at pT58, thereby stabilizing Myc to drive PD-L1-mediated immune suppression and NF-κB/CCL2-dependent NK cell exclusion in the pre-metastatic niche (PMID:29535359, PMID:29757193, PMID:40247147, PMID:40333987).

1. 2008 High

   Establishing EYA3 as a transcriptional co-activator in muscle differentiation resolved how EYA3 engages chromatin: it forms a SKI–SIX1–EYA3 complex on the MEF3 site of the Myogenin promoter to activate terminal differentiation genes.

   Evidence Reciprocal Co-IP, ChIP, reporter assays, and knockdown in C2C12 myoblasts

   PMID:19008232

   Open questions at the time

   • Whether EYA3 phosphatase activity is required for its co-activator function in myogenesis was not tested
   • Other genomic targets of the SKI–SIX1–EYA3 complex were not mapped
2. 2008 Medium

   EYA3 knockout mice revealed broad developmental functions—reduced bone mineral content, shorter body length, cardiac conduction defects, reduced muscle strength—without eye defects, establishing that mammalian EYA3 has pleiotropic roles distinct from the Drosophila eye specification paradigm.

   Evidence Comprehensive phenotyping of Eya3-null mice at the German Mouse Clinic

   PMID:19102749

   Open questions at the time

   • Molecular targets responsible for each phenotypic defect were not identified
   • Redundancy with other EYA family members was not formally assessed
3. 2010 Medium

   Identification of EYA3 as the strongest photoperiod-activated gene in the pars tuberalis, synergistically activating TSHβ with SIX1, placed EYA3 atop a conserved mammalian photoperiodic signaling cascade regulating seasonal reproduction.

   Evidence Microarray and in situ hybridization in sheep under controlled photoperiod; transcriptional reporter assays and acute light stimulation in mice

   PMID:20434341 PMID:21129973

   Open questions at the time

   • Upstream signals that induce EYA3 expression in response to light were not fully defined
   • Whether EYA3 phosphatase activity contributes to photoperiodic signaling is unknown
4. 2012 High

   Discovery that EWS/FLI1 upregulates EYA3 by repressing miR-708 revealed a mechanism by which Ewing sarcoma exploits EYA3 for DNA damage repair and chemoresistance, establishing EYA3's phosphatase as a survival factor in cancer.

   Evidence miR-708/EYA3 3′-UTR targeting validation, EYA3 knockdown with clonogenic survival and DNA repair assays in Ewing sarcoma cell lines

   PMID:22723308

   Open questions at the time

   • The specific EYA3 phosphatase substrates mediating chemoresistance were not identified at this stage
   • In vivo validation of miR-708-EYA3 axis was limited
5. 2018 High

   Three concurrent studies redefined EYA3 enzymology: its reported N-terminal Ser/Thr phosphatase activity was shown to arise from recruited PP2A-B55α, which EYA3 redirects to dephosphorylate c-Myc pT58, stabilizing Myc to drive PD-L1 upregulation and tumor immune evasion; separately, WDR1 was identified as an EYA3-specific tyrosine phosphatase substrate controlling actin cytoskeleton remodeling, and Src-dependent phosphorylation of EYA3 itself was shown to regulate its subcellular localization.

   Evidence Co-IP and in vitro phosphatase reconstitution with PP2A-B55α; phosphatase-dead mutant rescue and CD8+ T cell depletion in syngeneic tumor models; phosphotyrosine peptide microarray for WDR1 substrate identification; Src kinase assays with subcellular fractionation

   PMID:29440662 PMID:29535359 PMID:29757193

   Open questions at the time

   • The structural basis for EYA3–B55α interaction was unknown
   • How EYA3 selectively recruits PP2A-B55α versus B56α was unresolved
   • Whether WDR1 dephosphorylation by EYA3 is relevant in vivo was not shown
6. 2019 High

   Catalytic-dead EYA3 knock-in mice and pharmacological inhibition demonstrated that EYA3 tyrosine phosphatase activity is required for pathological vascular remodeling in pulmonary hypertension, validating EYA3 as a druggable target in vivo.

   Evidence Transgenic mice with inactivating mutation in EYA3 tyrosine phosphatase domain; pharmacological inhibition in rat pulmonary arterial hypertension model

   PMID:31515519

   Open questions at the time

   • The direct vascular substrate(s) of EYA3 tyrosine phosphatase in smooth muscle cells were not identified
   • Long-term therapeutic window and off-target effects of pharmacological inhibition were not assessed
7. 2019 High

   Mass spectrometry mapping of 13 Src-phosphorylated tyrosine residues on EYA3, with mutagenesis showing Y77, Y96, and Y237 are required for its pro-proliferative activity, defined the regulatory phosphorylation landscape of EYA3 itself.

   Evidence Native and bottom-up MS phosphosite mapping, site-directed mutagenesis with cell cycle analysis in HEK293T cells

   PMID:31847183

   Open questions at the time

   • Which downstream signaling pathways are affected by each specific phosphosite remains unknown
   • Physiological contexts in which Src-EYA3 phosphorylation occurs in vivo were not established
8. 2021 High

   In vivo target engagement was demonstrated: pharmacological EYA3 tyrosine phosphatase inhibition elevated H2AX-pY142 in Ewing sarcoma tumors and suppressed growth in cell line and patient-derived xenografts, confirming H2AX-pY142 as a bona fide in vivo substrate and linking EYA3 phosphatase to tumor angiogenesis via VEGFA.

   Evidence Benzarone treatment of xenograft and PDX models with H2AX-pY142 substrate engagement assay

   PMID:33649104

   Open questions at the time

   • Whether VEGFA regulation requires EYA3 phosphatase activity or its transcriptional co-activator function was not fully dissected
   • Selectivity of benzarone for EYA3 versus other targets is a concern
9. 2021 Medium

   A missense variant (p.Asn358Ser) in EYA3 was linked to oculo-auriculo-vertebral spectrum, with the mutant protein showing increased stability without loss of H2AX dephosphorylation; zebrafish eya3 knockdown produced craniofacial defects, establishing EYA3 as a craniofacial development gene.

   Evidence Exome sequencing, protein stability assays, H2AFX dephosphorylation assay, zebrafish morpholino knockdown

   PMID:33475861

   Open questions at the time

   • The variant was identified in a single family; broader genetic evidence is needed
   • How increased protein stability causes disease pathology is unclear
   • Whether gain-of-function or neomorphic activity underlies the phenotype was not determined
10. 2022 Medium

    Identification of the EYA3–SIX5–p300 complex on EGFR, VEGFD, and MMP promoters in hypoxic colorectal cancer cells extended EYA3's transcriptional co-activator role to hypoxia-driven tumor progression programs.

    Evidence Co-IP/mass spectrometry, ChIP on target promoters, benzarone inhibition in xenograft model

    PMID:35957720

    Open questions at the time

    • Whether the phosphatase activity of EYA3 is required for p300 recruitment and histone acetylation at these loci is unknown
    • The hypoxia-responsive element driving EYA3 expression/activity was not identified
11. 2023 Medium

    RBFOX2-regulated alternative splicing of EYA3 exon 7 was shown to generate isoforms with differential binding to SIX4 versus ZBTB1, controlling distinct transcriptional programs during myoblast proliferation and differentiation, revealing a splicing-based mechanism for EYA3 functional diversification.

    Evidence Mass spectrometry proteomics, transcriptomics, splicing analysis, EYA3 knockdown with proliferation/differentiation readouts in myoblasts

    PMID:38026174

    Open questions at the time

    • The structural basis for isoform-specific partner selection is unknown
    • In vivo relevance of the exon 7 splicing switch in muscle development has not been tested
12. 2025 High

    Cryo-EM and NMR structures of PP2A-B55α bound to EYA3 revealed that a conserved N-terminal peptide of EYA3 engages the B55α substrate-recruitment groove, providing the structural basis for how EYA3 redirects PP2A specificity; a designed inhibitory peptide (B55i) disrupts this interaction and destabilizes Myc in triple-negative breast cancer cells.

    Evidence Cryo-EM structure determination, NMR spectroscopy and dephosphorylation assays, B55i peptide competition in vitro and in TNBC cells with Myc pT58 readout

    PMID:40247147 PMID:40414499

    Open questions at the time

    • In vivo efficacy and pharmacokinetic properties of B55i or derivatives are untested
    • Whether the EYA3–B55α interaction has substrates beyond c-Myc in cells is not known
    • Structural data for full-length EYA3 bound to PP2A holoenzyme is lacking
13. 2025 High

    EYA3 was shown to activate NF-κB/CCL2 signaling in TNBC cells, with secreted CCL2 suppressing NK cell cytotoxicity and reducing NK infiltration in the pre-metastatic niche to promote metastasis, adding innate immune evasion to EYA3's oncogenic repertoire.

    Evidence EYA3 knockdown with NF-κB and CCL2 epistatic rescue, NK cell activation/depletion assays in vitro, syngeneic pre-metastatic niche models

    PMID:40333987

    Open questions at the time

    • Whether EYA3's phosphatase or co-activator function drives NF-κB activation is unresolved
    • The direct molecular link between EYA3 and NF-κB pathway activation has not been identified

• Key unresolved questions include: how EYA3's dual phosphatase and transcriptional activities are coordinated in physiological contexts; the full spectrum of PP2A-B55α substrates redirected by EYA3 beyond c-Myc; the structural basis for isoform-specific partner selection; and whether therapeutic disruption of the EYA3–B55α interface is effective in vivo.
• No integrated model connects EYA3 phosphatase and transcriptional activities in the same cellular context
• Full-length EYA3 structure remains undetermined
• In vivo therapeutic targeting of the EYA3–B55α interface is untested