ZFYVE1

ZFYVE1/DFCP1 is an ER-associated protein with tandem C-terminal FYVE zinc-binding domains and a nucleotide-binding region that operates at multiple membrane interfaces governing autophagosome biogenesis, lipid droplet metabolism, and innate antiviral signaling (PMID:11024279, PMID:37422481). As a membrane-activated ATPase that dimerizes in an ATP-dependent manner, it is selectively required for autophagic flux of p62-marked cargo in aggrephagy, mitophagy, and micronucleophagy but not bulk autophagy; ATP binding/hydrolysis-defective mutants reach omegasomes yet fail to constrict them, delaying release of nascent autophagosomes from large omegasomes (PMID:37422481). At the ER-lipid droplet interface it acts as an effector of GTP-bound Rab18, engaging the Rab18-ZW10 complex to tether ER-LD contacts and promote LD growth, with its ER-targeting domain rather than FYVE-mediated PI3P binding directing LD localization (PMID:30970241, PMID:31293035). It further recruits and retains ATGL on lipid droplets in starved cells, restraining lipolysis (PMID:39566849). In innate immunity ZFYVE1 exerts receptor-specific control, positively regulating TLR3 signaling by binding poly(I:C) and increasing TLR3 ligand affinity through its FYVE domain, while negatively regulating MDA5 by binding viral RNA and impairing MDA5 ligand engagement and oligomerization (PMID:31388100, PMID:32251420).

1. 2000 Low

   Established the existence and domain architecture of DFCP1, raising the question of what cellular process a double-FYVE, nucleotide-binding protein serves.

   Evidence Molecular cloning, sequence analysis, and confocal imaging of transfected cells

   PMID:11024279

   Open questions at the time

   • No functional assay linking the protein to a specific pathway
   • Vesicular localization inferred only from overexpression
2. 2015 Medium

   Showed endogenous DFCP1 associates with mitochondria and redistributes to dotted structures partly overlapping LC3 autophagosomes upon starvation, connecting it to phagophore/omegasome formation.

   Evidence Immunofluorescence of endogenous protein with organelle markers in HeLa cells under normal and starvation conditions

   PMID:25876663

   Open questions at the time

   • Co-localization is correlative, not functional
   • Does not define the molecular role at the omegasome
3. 2019 High

   Defined DFCP1 as a Rab18 effector that tethers ER-LD contacts and drives LD growth, establishing a membrane-trafficking role distinct from autophagy.

   Evidence Super-resolution live imaging, gain/loss-of-function, and Co-IP with Rab18 and the ZW10 complex; BSCL2 depletion

   PMID:30970241 PMID:31293035

   Open questions at the time

   • Mechanism of how contact tethering promotes triglyceride loading not resolved
   • Relationship between LD and omegasome pools of DFCP1 not fully mapped
4. 2019 High

   Demonstrated receptor-specific immune roles, showing ZFYVE1 binds poly(I:C) and the TLR3 ectodomain via its FYVE domain to enhance TLR3 ligand affinity and antiviral transcription.

   Evidence Reporter assays, reciprocal Co-IP, domain mapping, ligand binding assay, and Zfyve1-/- mouse model

   PMID:31388100

   Open questions at the time

   • Structural basis of FYVE-TLR3 contact unresolved
   • How the same domain mediates both TLR3 and lipid functions unclear
5. 2020 High

   Showed ZFYVE1 selectively restrains MDA5 (not RIG-I) signaling by binding viral RNA and blocking MDA5 ligand engagement and oligomerization, revealing opposing receptor-specific immunomodulation.

   Evidence Co-IP, viral RNA binding and MDA5 oligomerization assays, and Zfyve1-/- mice challenged with EMCV versus VSV

   PMID:32251420

   Open questions at the time

   • How RNA binding discriminates between receptor pathways not defined
   • Subcellular site of the ZFYVE1-MDA5 interaction unknown
6. 2023 High

   Reconstituted DFCP1 as a membrane-activated, ATP-dependent dimerizing ATPase whose hydrolysis constricts omegasomes specifically for selective autophagy, defining its catalytic mechanism.

   Evidence In vitro ATPase and dimerization assays, ATPase-dead mutants, KO cells, and live imaging of omegasome constriction with selective autophagy reporters

   PMID:37422481

   Open questions at the time

   • Physical link between ATPase-driven constriction and membrane scission incomplete
   • How selectivity for cargo-specific autophagy is achieved not resolved
7. 2024 Medium

   Identified a lipolysis-regulatory function whereby DFCP1 recruits and retains ATGL on lipid droplets in starvation, slowing lipolysis.

   Evidence Co-IP of DFCP1 with ATGL, pharmacological inhibitor experiments, and live-cell LD dynamics assays in starved cells

   PMID:39566849

   Open questions at the time

   • Direct binding interface with ATGL not mapped
   • Integration with the Rab18-dependent LD contact role unclear
8. 2024 Medium

   Placed DFCP1 downstream of miR-146b-5p as a required autophagic-flux component whose suppression contributes to cardiac hypertrophy, linking its function to disease physiology.

   Evidence miRNA mimic/inhibitor transfection, luciferase target validation, autophagy flux assays, and in vitro/in vivo hypertrophy models

   PMID:38649132

   Open questions at the time

   • Whether the effect reflects selective versus bulk autophagy not addressed
   • Direct mechanistic chain from DFCP1 loss to hypertrophy not established
9. 2025 Low

   Extended antiviral regulation to a fish ortholog interacting with IRF3/7 and reducing their protein levels, hinting at additional regulatory targets.

   Evidence Co-IP, luciferase reporters, overexpression/knockdown, proteasome/lysosome inhibitors, and viral replication assay in black carp (ortholog)

   PMID:40250505

   Open questions at the time

   • Not validated in mammalian systems
   • Single Co-IP with reporter assays; degradation mechanism not defined

• How a single ER-associated FYVE-ATPase coordinates its distinct roles in omegasome constriction, ER-LD tethering, and bidirectional innate immune signaling remains unresolved.
• No structural model integrating ATPase, FYVE, and RNA/protein-binding activities
• Regulatory switches partitioning DFCP1 among autophagy, lipid, and immune functions unknown