FZD2

FZD2 is a Wnt receptor that transduces both canonical (β-catenin-dependent) and noncanonical Wnt signaling in a cell-type- and ligand-specific manner to control developmental morphogenesis and tissue regeneration (PMID:36867021, PMID:41257888). In limb mesenchyme it integrates canonical Wnt/β-catenin signaling with the noncanonical WNT5A/planar cell polarity pathway, and a frameshift mutation in its Dishevelled-interacting domain reduces canonical signaling and disrupts digit chondrocyte elongation and orientation (PMID:36867021). Loss-of-function and dominant-negative FZD2 variants cause Robinow syndrome/OMOD2: missense variants increase nuclear β-catenin and TWIST1 and inhibit chondrogenesis in frontonasal cells, and the Pro142Lys variant selectively abolishes noncanonical reporter activation and responsiveness to WNT5A, defining a single residue that alters ligand selectivity (PMID:38967226). FZD2 acts with co-receptors and partners — cooperating with Ror2 in an LRP-dependent manner to potentiate Wnt3a-driven canonical signaling (PMID:18215320) — and engages Wnt5a/b, Wnt3, and Wnt2 ligands (PMID:31907106, PMID:32766155). In tissue regeneration, mesenchymal FZD2 maintains alveolar fibroblast identity and supports alveolar repair via PI3K-AKT signaling, while endothelial FZD2 drives canonical Wnt/β-catenin–dependent proliferation (PMID:41257888), and in cardiomyocytes FZD2 restrains YAP activity and cell-cycle re-entry through an effector independent of canonical Wnt and Hippo/LATS signaling [PMID:bio_10.1101_2024.07.26.605158]. FZD2 receptor maturation and stability depend on the ER-resident scramblases VMP1 and TMEM41B, linking ER lipid metabolism to FZD2-dependent Wnt signaling (PMID:39968886). In cancer, FZD2 drives epithelial-to-mesenchymal transition, stemness, and therapy resistance through noncanonical outputs including STAT3, YAP1, and TGF-β1/Smad3 (PMID:31907106, PMID:32766155).

1. 2008 Medium

   Established that FZD2 does not act alone but cooperates selectively with the co-receptor Ror2 to potentiate canonical Wnt signaling, defining receptor partner specificity.

   Evidence Overexpression/knockdown with domain-deletion constructs and STF luciferase reporter assays plus Dkk1/Krm1 inhibition in H441 lung carcinoma cells

   PMID:18215320

   Open questions at the time

   • Whether Ror2-FZD2 cooperation operates in non-carcinoma or developmental contexts not tested
   • Direct physical interaction surfaces beyond CRD-dependence not mapped
2. 2014 Low

   Linked FZD2/WNT5A noncanonical signaling to EMT and metastasis through FYN and STAT3, implicating the receptor in cancer dissemination.

   Evidence Brief communication summary (no experimental detail in abstract)

   PMID:34450691

   Open questions at the time

   • No experimental detail available in the abstract
   • Direct FZD2-FYN-STAT3 mechanistic connection not demonstrated
3. 2020 Medium

   Showed FZD2 binds specific Wnt ligands and that ligand engagement and protein stabilization route into discrete oncogenic outputs, connecting ligand identity to downstream pathway choice.

   Evidence Co-immunoprecipitation of FZD2-Wnt binding, siRNA knockdown, mammosphere/flow cytometry, and ubiquitination/phosphorylation assays with STAT3 readouts in breast and esophageal cancer cells

   PMID:31907106 PMID:32766155

   Open questions at the time

   • Ubiquitin ligase mediating FZD2 turnover not identified
   • Kinase driving WNT2-induced FZD2 phosphorylation unknown
4. 2021 Low

   Implicated FZD2 in TGF-β1-induced EMT via Notch signaling in breast cancer, extending its noncanonical signaling repertoire.

   Evidence siRNA knockdown, EMT marker western/IF, pathway modulation, and xenograft

   PMID:33832493

   Open questions at the time

   • No direct mechanistic link between FZD2 and Notch established
   • Single knockdown approach without rescue
5. 2022 Medium

   Connected Wnt5a/FZD2 noncanonical signaling to androgen receptor activity in enzalutamide-resistant prostate cancer, framing FZD2 as a therapy-resistance node.

   Evidence BERA-Wnt5a siRNA knockdown, AR/noncanonical pathway western blots, and xenograft tumor model

   PMID:35930737

   Open questions at the time

   • Mechanism coupling FZD2 to AR splice variant stabilization not defined
   • Whether effect is FZD2-specific vs other Wnt5a receptors not resolved
6. 2023 High

   Demonstrated in vivo that FZD2 mediates both canonical and WNT5A/PCP signaling in limb mesenchyme, and that disruption of its Dishevelled-interacting domain phenocopies Robinow syndrome/OMOD2.

   Evidence Mouse genetic model with a frameshift mutation, conditional FZD disruption, β-catenin reporters, and skeletal analysis

   PMID:36867021

   Open questions at the time

   • How a single domain mutation partitions canonical vs PCP outputs not fully resolved
   • Ligand specificity in limb mesenchyme not directly tested
7. 2024 High

   Resolved how human FZD2 disease variants act, showing dominant-negative canonical effects and a single residue (Pro142Lys) that selectively alters noncanonical/ligand responsiveness.

   Evidence Retroviral overexpression in chicken frontonasal mass, canonical/noncanonical luciferase reporters, β-catenin nuclear localization, and chondrogenesis assays

   PMID:38967226

   Open questions at the time

   • Structural basis of altered WNT5A binding not determined
   • Whether dominant-negative effect involves dimerization with wild-type FZD2 unknown
8. 2024 Medium

   Identified a developmentally distinct FZD2 function restraining cardiomyocyte YAP activity and cell-cycle re-entry through an effector independent of canonical Wnt and Hippo signaling.

   Evidence Conditional cardiomyocyte FZD2 knockout, neonatal CM KD/overexpression, YAP activity and β-catenin localization assays, and myocardial infarction model (preprint)

   PMID:bio_10.1101_2024.07.26.605158

   Open questions at the time

   • The β-catenin- and Hippo-independent effector linking FZD2 to YAP is unidentified
   • Not yet peer-reviewed
9. 2025 Medium

   Established the cell-biological prerequisite for FZD2 signaling by showing ER scramblases VMP1/TMEM41B are required for FZD2 maturation and stability.

   Evidence Genetic mutation of Vmp1/Tmem41b in mouse ESCs, differentiation assays, and FZD2 protein maturation/stability analysis

   PMID:39968886

   Open questions at the time

   • Mechanism by which lipid scrambling supports FZD2 folding/trafficking not defined
   • Whether other FZD receptors share this dependence not tested
10. 2025 Medium

    Defined cell-type-resolved FZD2 functions in lung — mesenchymal AF1 identity maintenance via PI3K-AKT and endothelial canonical Wnt-driven proliferation — and identified upstream epigenetic control of FZD2 by MBD2.

    Evidence Cell-type-specific conditional knockouts, bleomycin/LPS lung injury models, scRNA-seq, MBD2 knockout with ChIP for FZD2 promoter binding

    PMID:40081619 PMID:41257888

    Open questions at the time

    • How FZD2 selects PI3K-AKT vs canonical output in different cell types not mechanistically resolved
    • Direct effectors downstream of FZD2 in fibroblast identity not identified
11. 2025 Medium

    Showed FZD2 and FZD7 activate β-catenin with distinct kinetics, conferring non-redundant roles in directing mesoderm fate, establishing temporal signaling specificity among Frizzleds.

    Evidence Selective FZD2- and FZD7-specific antibody agonists in hPSCs, directed differentiation, and β-catenin kinetics measurement

    PMID:39824186

    Open questions at the time

    • Molecular basis of kinetic difference between FZD2 and FZD7 unknown
    • Whether kinetic specificity generalizes beyond mesoderm not tested

• The identity of the non-canonical effector by which FZD2 restrains YAP, and the general rules governing how FZD2 partitions canonical, PCP, PI3K-AKT, and STAT3 outputs across cell types, remain unresolved.
• No unified model for FZD2 output selection
• Structural determinants of ligand selectivity only partially mapped
• Direct intracellular effectors largely undefined