ARRDC3

ARRDC3 is an α-arrestin adaptor protein that functions as a trafficking hub, recruiting NEDD4-family E3 ubiquitin ligases (NEDD4, WWP2, Itch) via bivalent engagement of its C-terminal PPXY motifs to promote ubiquitination and lysosomal degradation of diverse transmembrane receptors and signaling effectors including integrin β4, β2-adrenergic receptor, PAR1 (via ALIX/ESCRT-III), the insulin receptor, AXL, and the Hippo pathway co-activators YAP and TAZ (PMID:20603614, PMID:24379409, PMID:26490116, PMID:27226565, PMID:32156724, PMID:29416926, PMID:33722977, PMID:38389126). Its N-terminal arrestin-fold domain contains an electropositive surface that mediates ligand-independent receptor binding, while its scaffolding output is toggled by phosphorylation: insulin receptor-mediated phosphorylation at Y382 promotes IR internalization, and phosphorylation at Y394 switches ARRDC3 from WWP2 binding to c-Src SH2 domain engagement, thereby redirecting cargo trafficking versus kinase signaling (PMID:25220262, PMID:32156724, PMID:40409556). ARRDC3 localizes primarily to early endosomes where it delays β2AR recycling into SNX27-positive tubules, prolongs endosomal signaling, and through its PPXY-mediated sequestration of TAZ and Itch-dependent degradation of YAP functions as a tumor suppressor in breast and renal cell carcinomas by attenuating Hippo, JNK, and Akt/ERK signaling (PMID:27226565, PMID:29348172, PMID:33722977, PMID:29416926).

1. 2010 High

   The initial identification of ARRDC3 as a functional adaptor established that it directly binds phosphorylated integrin β4, promoting its internalization and degradation, thereby revealing ARRDC3 as a tumor-suppressive regulator of receptor turnover.

   Evidence Co-immunoprecipitation, overexpression/knockdown with proliferation, migration, invasion, and xenograft assays in breast cancer cells

   PMID:20603614

   Open questions at the time

   • Mechanism of ITGβ4 ubiquitination (which E3 ligase) was not identified
   • Whether ARRDC3 PPXY motifs mediate ligase recruitment in this context was unknown
2. 2013 High

   Structural and biophysical dissection of the ARRDC3–NEDD4 interaction defined the molecular basis for E3 ligase recruitment: bivalent engagement of two PPXY motifs with NEDD4 WW domains achieves ~300 nM affinity, establishing the mechanistic framework for ARRDC3's adaptor function.

   Evidence ITC binding assays, X-ray crystallography at 1.1 and 1.7 Å resolution, mutagenesis, Co-IP in HEK293 cells

   PMID:24379409

   Open questions at the time

   • Whether bivalent binding mode applies to other NEDD4-family members (WWP2, Itch) was not tested
   • No structural information for the full-length ARRDC3 protein
3. 2014 High

   Crystal structures of the ARRDC3 N-terminal arrestin fold revealed a large electropositive surface essential for β2AR binding, demonstrating that α-arrestins recognize receptors through a mechanism analogous to classical β-arrestins.

   Evidence X-ray crystallography at 1.73 and 2.8 Å, mutagenesis of basic-patch residues, receptor binding assays

   PMID:25220262

   Open questions at the time

   • No co-crystal with β2AR or other receptor was obtained
   • Whether the same surface mediates all receptor interactions was not addressed
4. 2014 Medium

   Epigenetic silencing of ARRDC3 by SIRT2 in basal-like breast cancer provided a mechanism for how ARRDC3 tumor-suppressive function is lost, linking histone deacetylation at the ARRDC3 promoter to its transcriptional repression.

   Evidence ChIP showing SIRT2 occupancy at ARRDC3 promoter, class III HDAC inhibitor rescue of expression

   PMID:24457910

   Open questions at the time

   • Whether SIRT2-mediated silencing occurs broadly across cancer types is unknown
   • No in vivo validation of SIRT2 inhibition restoring ARRDC3-dependent tumor suppression
5. 2015 High

   Discovery that ARRDC3 bridges ALIX to the NEDD4-family ligase WWP2 for GPCR sorting established a new ESCRT-dependent trafficking route: ARRDC3 is required for WWP2-mediated ALIX ubiquitination and subsequent PAR1 lysosomal degradation via CHMP4B/ESCRT-III.

   Evidence siRNA depletion, Co-IP, colocalization at late endosomes, systematic screen of 9 NEDD4-family E3 ligases

   PMID:26490116

   Open questions at the time

   • Direct physical interaction between ARRDC3 and PAR1 was not demonstrated in this study
   • Whether ARRDC3 bridges ALIX-WWP2 for other GPCRs was untested
6. 2016 High

   Localization of ARRDC3 to EEA1-positive early endosomes and its role in delaying β2AR recycling into SNX27-occupied tubules revealed a new function: controlling endosomal residence time to tune receptor signaling output.

   Evidence Confocal imaging, Co-IP, live-cell imaging of endosomal tubules, cAMP signaling assays with ARRDC3 overexpression/knockdown

   PMID:27226565

   Open questions at the time

   • Molecular mechanism by which ARRDC3 excludes β2AR from SNX27 tubules was not defined
   • Whether this recycling delay generalizes to other GPCRs was not tested
7. 2017 Medium

   Adipocyte-specific Arrdc3 deletion revealed a role in energy metabolism by increasing UCP1 expression in white adipose tissue through a mechanism independent of canonical β-adrenergic signaling, expanding ARRDC3's physiological roles beyond cancer.

   Evidence Conditional adipocyte-specific knockout mice, β-adrenergic stimulation assays, metabolic phenotyping

   PMID:28291835

   Open questions at the time

   • The pathway by which ARRDC3 suppresses UCP1 in the absence of β-adrenergic signaling was not identified
   • No direct target mediating this effect was established
8. 2018 High

   Identification of YAP and TAZ as ARRDC3 targets connected ARRDC3 to Hippo pathway regulation: ARRDC3 promotes Itch-mediated YAP ubiquitination and degradation (conserved from Drosophila to mammals) and independently sequesters TAZ via PPXY–WW domain interactions, suppressing cancer cell invasion and metastasis.

   Evidence TAP-MS interactome, Co-IP with PPXY mutagenesis, ubiquitination assays, Drosophila genetics, in vivo lung metastasis model

   PMID:29364502 PMID:29416926 PMID:33722977

   Open questions at the time

   • Whether ARRDC3-mediated YAP/TAZ regulation occurs in all tissue contexts is unknown
   • Relative contributions of YAP degradation vs. TAZ sequestration to tumor suppression are not quantified
9. 2018 High

   Re-expression of ARRDC3 in invasive breast carcinoma cells restored ALIX-dependent PAR1 lysosomal degradation and attenuated JNK signaling, providing direct functional evidence for ARRDC3 as a tumor suppressor through receptor trafficking.

   Evidence Inducible lentiviral re-expression, flow cytometry trafficking assays, JNK inhibitor phenocopy, invasion assays

   PMID:29348172

   Open questions at the time

   • Whether ARRDC3 loss is sufficient to initiate tumorigenesis or only promotes invasion was not distinguished
10. 2020 High

    ARRDC3 was identified as a direct substrate and trafficking adaptor for the insulin receptor: IR phosphorylates ARRDC3 at Y382, and liver-specific Arrdc3 knockout increases surface IR abundance, enhancing hepatic insulin sensitivity and gluconeogenic gene regulation.

    Evidence Liver-specific knockout mice, euglycemic-hyperinsulinemic clamps, Co-IP, plasma membrane fractionation, Y382 mutagenesis

    PMID:32156724

    Open questions at the time

    • Which E3 ligase mediates IR ubiquitination downstream of ARRDC3 was not identified
    • Whether Y382 phosphorylation feeds back to regulate ARRDC3 stability was not tested
11. 2023 High

    Ubiquitination of ARRDC3 itself, mediated through its PPXY motifs, was shown to regulate its own stability, subcellular localization, and WWP2 interaction, establishing a self-regulatory feedback loop essential for GPCR trafficking function.

    Evidence PPXY mutagenesis, ubiquitination assays, subcellular fractionation/imaging, GPCR trafficking assays

    PMID:37223976

    Open questions at the time

    • Which specific ubiquitin chain types on ARRDC3 mediate degradation vs. localization was not resolved
    • Deubiquitinase(s) counteracting ARRDC3 ubiquitination are unknown
12. 2024 Medium

    Extension of ARRDC3's receptor-targeting repertoire to AXL showed that ARRDC3 promotes AXL ubiquitination and degradation, negatively regulating Akt/ERK signaling and modulating sunitinib sensitivity in renal cell carcinoma.

    Evidence Co-IP with wild-type and mutant proteins, CRISPR-Cas9 ARRDC3 knockout, ubiquitination assays, drug sensitivity experiments

    PMID:38389126

    Open questions at the time

    • The E3 ligase mediating AXL ubiquitination via ARRDC3 was not identified
    • Whether ARRDC3-AXL interaction is direct or bridged was not fully resolved
13. 2025 High

    A phospho-regulatory switch at Y394 was discovered that determines ARRDC3 partner selection: phosphorylation at Y394 promotes c-Src SH2 binding and disrupts WWP2 interaction, diverting ARRDC3 from cargo trafficking to kinase regulation.

    Evidence Y394 mutagenesis, Co-IP, SH2 domain binding assays, PAR1 trafficking assays, c-Src activity assays

    PMID:40409556

    Open questions at the time

    • The kinase(s) that phosphorylate Y394 in vivo are unknown
    • Physiological contexts in which the Y394 switch is activated have not been defined
14. 2025 Medium

    ARRDC3-mediated YAP degradation was linked to antiviral immunity: by promoting lysosomal YAP turnover, ARRDC3 derepresses the interferon pathway and inhibits enterovirus and paramyxovirus replication.

    Evidence Overexpression/knockdown of ARRDC3 and YAP, lysosomal inhibitors, interferon reporter assays, multi-virus replication assays

    PMID:40701343

    Open questions at the time

    • Whether ARRDC3 antiviral function operates in vivo is untested
    • The mechanism by which YAP suppresses interferon signaling independently of transcription is poorly defined

• Key unresolved questions include the identity of kinase(s) phosphorylating Y394, how ARRDC3's dual early- and late-endosome localization is coordinated, whether ARRDC3 has additional non-receptor substrates, and the structural basis for full-length ARRDC3 in complex with any receptor or E3 ligase.
• No full-length ARRDC3 structure or receptor co-complex exists
• Deubiquitinases regulating ARRDC3 turnover are unidentified
• Tissue-specific functions beyond liver, adipose, and breast remain largely unexplored