MARCHF3

MARCHF3 (MARCH3) is a membrane-associated RING-CH-type E3 ubiquitin ligase that functions as a negative regulator of inflammatory and growth-factor receptor signaling by ubiquitinating transmembrane receptors and cytoplasmic substrates to drive their lysosomal or proteasomal degradation (PMID:30442668, PMID:34785732, PMID:35075102). It localizes to endosomal vesicles, partially colocalizing with the transferrin receptor and associating with syntaxin 6 and MARCH-II, with both its RING finger and PDZ-binding motif required for correct localization and function (PMID:16428329). A recurring mechanistic theme is receptor turnover: MARCH3 binds and ubiquitinates IL-1RI (K48-linked at K409) to attenuate IL-1β/NF-κB signaling, IL-6Rα/gp130 to suppress IL-6/STAT3 signaling and colitis-associated carcinogenesis, IL-3Rα (K48-linked at K377), and, redundantly with MARCH2, IL-5Rα (K27-linked) and the Zika virus entry factor TIM-1 (K48-linked), thereby controlling inflammatory cytokine responses, eosinophilia, and viral infectivity in vivo (PMID:30442668, PMID:34785732, PMID:35075102, PMID:35982175, PMID:40817191). Its ligase activity is activated upon IL-1β stimulation through CDC25A-mediated dephosphorylation (PMID:30442668). Beyond receptors, MARCH3 ubiquitinates cytoplasmic substrates including GRB2 to dampen RAF/MEK/ERK signaling, PARP1 to engage cGAS-STING-driven antigen cross-presentation, GPX4 in ferroptosis regulation, and HK2 to restrain glycolysis, linking it to tumor suppression in several contexts (PMID:37626338, PMID:39608977, PMID:39229924, PMID:42044316). MARCHF3 expression is itself transcriptionally controlled, including by ATF4, and is induced by TLR4 activation (PMID:26694610, PMID:39608977).

1. 2006 Medium

   Established MARCH3 as an endosome-associated protein whose RING finger and PDZ-binding motif govern its localization and ability to regulate membrane trafficking, framing it as a membrane-acting RING-CH ligase.

   Evidence Immunofluorescence, reciprocal Co-IP, mutational analysis, and transferrin uptake assays in HeLa cells

   PMID:16428329

   Open questions at the time

   • No direct demonstration of ubiquitin ligase catalytic activity in this study
   • Endogenous substrates not yet identified
2. 2015 Medium

   Connected MARCH3 to innate immune regulation by showing TLR4/LPS induces it to ubiquitinate and downregulate the inhibitory Fc receptor FcγRIIb, indicating a role in controlling surface receptor levels in monocytes.

   Evidence siRNA knockdown, surface flow cytometry, and ubiquitination assay following LPS stimulation in monocytes

   PMID:26694610

   Open questions at the time

   • Ubiquitin linkage type and acceptor lysine not defined
   • Direct vs indirect substrate engagement not established
3. 2016 Medium

   Revealed a vascular function whereby MARCH3 controls endothelial barrier integrity and junctional protein abundance, linking its activity to FoxO1 regulation.

   Evidence siRNA library screen, transcriptome analysis, and junctional protein localization in endothelial cells

   PMID:27616439

   Open questions at the time

   • Direct substrate mediating barrier effect not identified
   • Mechanistic link to ubiquitination not shown
4. 2018 High

   Defined the canonical mechanism: MARCH3 directly binds IL-1RI and catalyzes K48-linked polyubiquitination at a specific lysine for lysosomal degradation, with activity switched on by CDC25A dephosphorylation, establishing it as an inducible brake on NF-κB inflammation in vivo.

   Evidence Reciprocal Co-IP, K409 mutagenesis, ubiquitination assays, KO mice, and Listeria infection model

   PMID:30442668

   Open questions at the time

   • Phosphatase regulation generality across other substrates untested
   • Structural basis of substrate selection unknown
5. 2021 High

   Extended the receptor-degradation paradigm to the IL-6 pathway, showing MARCH3 ubiquitinates both IL-6Rα and gp130 to suppress STAT3 signaling and colitis-associated cancer, generalizing its role as a cytokine receptor regulator.

   Evidence Reciprocal Co-IP, site-directed mutagenesis (K401/K849), KO mice, DSS/AOM colitis and cancer models

   PMID:34785732

   Open questions at the time

   • Whether IL-6Rα and gp130 are ubiquitinated independently or as a complex not resolved
6. 2022 High

   Showed MARCH3 negatively regulates IL-3 signaling via K48-linked, proteasomal degradation of IL-3Rα and that its loss worsens sepsis, broadening its substrate range to additional hematopoietic cytokine receptors.

   Evidence Reciprocal Co-IP, K377 mutagenesis, KO mice, CLP sepsis model

   PMID:35075102

   Open questions at the time

   • Determinants distinguishing proteasomal vs lysosomal routing across substrates unclear
7. 2022 High

   Demonstrated functional redundancy with MARCH2 in degrading IL-5Rα via atypical K27-linked ubiquitination, controlling eosinophil numbers and airway inflammation, indicating linkage-type flexibility.

   Evidence Reciprocal Co-IP, mutagenesis, MARCH2/3 single and double KO mice, OVA airway allergy model

   PMID:35982175

   Open questions at the time

   • Mechanism dictating K27 vs K48 linkage choice unknown
   • Relative contributions of MARCH2 vs MARCH3 not quantified
8. 2023 Medium

   Identified a cytoplasmic substrate, GRB2, establishing that MARCH3 dampens RAF/MEK/ERK growth signaling and suppresses hepatocellular carcinoma, extending its reach beyond membrane receptors.

   Evidence RNA-seq, mass spectrometry, Co-IP, knockdown/overexpression, in vitro and in vivo HCC tumor models

   PMID:37626338

   Open questions at the time

   • Ubiquitin acceptor site on GRB2 not mapped
   • Linkage type not defined
9. 2024 Medium

   Linked MARCH3 to nucleic-acid immune sensing by showing it degrades PARP1 to enable cGAS-STING activation and antigen cross-presentation, and that ATF4 transcriptionally drives its expression.

   Evidence Co-IP, ubiquitination assay, flow cytometry, subcutaneous/orthotopic HCC models with KO/OE

   PMID:39608977

   Open questions at the time

   • Subcellular site of PARP1 ubiquitination not localized
   • How a membrane ligase accesses nuclear PARP1 unresolved
10. 2024 Medium

    Implicated MARCH3 in ferroptosis and lipid metabolism through degradation of GPX4 under intermittent hypoxia, expanding its substrate set toward redox/metabolic regulators.

    Evidence Co-IP, western blot, siRNA/overexpression, E3 prediction, animal intermittent-hypoxia model

    PMID:39229924

    Open questions at the time

    • Direct vs indirect targeting of GPX4 not confirmed by mutagenesis
    • Linkage type unspecified
11. 2024 Low

    Suggested MARCH3 restrains inflammasome activity by ubiquitinating NLRP3 in macrophages, with miRNA-mediated suppression promoting M1 polarization and pyroptosis.

    Evidence miR-24-3p modulation, MARCH3 gain/loss-of-function, NLRP3 ubiquitination assay in rat macrophages

    PMID:38530976

    Open questions at the time

    • Indirect evidence through miRNA modulation; single ubiquitination method
    • No acceptor-site mapping or reciprocal validation
12. 2024 Low

    Provided a second context for MARCH3-mediated NLRP3 ubiquitination, in a neuronal Alzheimer's model where amyloid-β reduces the interaction.

    Evidence Endogenous Co-IP with ubiquitin immunoblot, SAMP8 AD mouse and Aβ1-42 cell models

    PMID:39556273

    Open questions at the time

    • Single Co-IP without reciprocal validation
    • Direct catalytic activity on NLRP3 not demonstrated
13. 2025 High

    Established MARCH3 (with MARCH2) as an antiviral restriction factor by degrading the viral entry receptor TIM-1 via K48 linkage, limiting Zika virus infectivity in a TIM-1-dependent manner in vivo.

    Evidence Reciprocal Co-IP, K346/K338 mutagenesis, MARCH2/3 KO mice, TIM-1 KO reconstitution, ZIKV infection

    PMID:40817191

    Open questions at the time

    • Breadth of TIM-1-dependent viruses restricted not defined
    • Relative MARCH2/MARCH3 contribution not dissected
14. 2025 Low

    Proposed MARCH3 degrades SIGLEC1 to inactivate NF-κB and protect retinal cells from hyperglycemic stress, adding another candidate substrate.

    Evidence Co-IP, cycloheximide chase, siRNA/overexpression in ARPE19 cells

    PMID:40682693

    Open questions at the time

    • No mutagenesis of ubiquitination sites
    • Single-lab, single-method interaction evidence
15. 2026 Medium

    Showed MARCH3 targets the glycolytic enzyme HK2 for degradation, suppressing glycolysis and tumor growth and enhancing chemosensitivity in nasopharyngeal carcinoma, reinforcing a metabolic/tumor-suppressive role.

    Evidence Co-IP, GST pull-down, cycloheximide chase, ubiquitination assay, in vivo NPC model

    PMID:42044316

    Open questions at the time

    • Acceptor lysine and linkage type on HK2 not mapped

• It remains unresolved what governs MARCH3's substrate selectivity and its choice of ubiquitin linkage type (K48 vs K27) and degradation route (lysosomal vs proteasomal) across its diverse membrane and cytoplasmic targets.
• No structural model of substrate recognition
• Mechanism of linkage-type selection unknown
• How a membrane ligase engages cytoplasmic/nuclear substrates like PARP1 unclear