VPS18

VPS18 is a core subunit of the HOPS and CORVET endosomal membrane-tethering complexes that drives the delivery of cargo to the lysosome/vacuole through endocytic, autophagic, biosynthetic, and phagocytic routes, and is conserved from yeast vacuolar biogenesis to mammalian lysosomal function (PMID:1944264, PMID:22854957, PMID:41526335). In humans, its C-terminal RING domain forms a zinc-dependent RING-RING heterodimer with VPS41 that integrates VPS41 into endogenous HOPS complexes, a recruitment mechanism not conserved in yeast (PMID:28931724). Beyond tethering, VPS18 acts as an E3 ubiquitin ligase that modulates signaling, ubiquitinating the scaffold PELP1 to restrain ERα activation (PMID:31015428). Through its control of lysosomal degradation, VPS18 governs the turnover of specific cargo: it promotes lysosomal degradation of EGFR to suppress ERK-MAPK signaling and lung tumorigenesis (PMID:40615043), degrades Lysyl Oxidase to permit Purkinje-cell dendritogenesis (PMID:22699122), and conversely stabilizes PD-L1 by promoting its glycosylation and trans-Golgi recycling, such that VPS18 loss enhances antitumor immunity (PMID:39413192). VPS18 is also required for phagosome-lysosome fusion and phagosomal membrane integrity, including restriction of Mycobacterium tuberculosis in macrophages (PMID:18923146, PMID:39888996). Loss of VPS18 produces cell-type-specific phenotypes spanning neurodegeneration and neuronal migration defects (acting upstream of β1 integrin) (PMID:22854957), melanosome biogenesis failure (PMID:16827750), and a neutrophil maturation arrest associated with autophagosome accumulation and a patient presenting with neutropenia (PMID:41526335).

1. 1991 High

   Established the founding function of VPS18 as a vacuolar peripheral membrane protein required for organelle biogenesis and hydrolase delivery, defining the protein's core trafficking role.

   Evidence Gene cloning by complementation, deletion alleles, cell fractionation, and EM/fluorescence microscopy in S. cerevisiae

   PMID:1944264

   Open questions at the time

   • Did not define molecular partners or complex membership
   • No mechanism for how the protein supports vacuole formation
2. 2001 Medium

   Defined the conserved domain architecture (clathrin repeat, coiled-coils, C-terminal RING zinc finger) and linked vacuolar function to organelle positioning and polarized growth in a fungal ortholog.

   Evidence Gene cloning, HA-tagging immunofluorescence, and nuclear migration mutant phenotyping in A. nidulans

   PMID:11810240

   Open questions at the time

   • RING domain function not biochemically tested
   • Single fungal system, not validated in mammals
3. 2005 Medium

   Showed at the organismal level that vps18 loss disrupts endosomal-lysosomal trafficking and apical membrane delivery, producing tissue-specific liver pathology.

   Evidence Zebrafish insertional mutant histology and light microscopy of liver

   PMID:16000385

   Open questions at the time

   • Molecular trafficking step affected not pinpointed
   • No cargo identified
4. 2006 Medium

   Connected VPS18/HOPS-mediated endolysosomal tethering to lysosome-related organelle biogenesis by demonstrating a requirement for melanosome maturation.

   Evidence Zebrafish insertional mutant with splicing analysis, EM of melanosomes, optokinetic assay

   PMID:16827750

   Open questions at the time

   • Direct role in melanosome cargo delivery not resolved
   • HOPS complex membership inferred, not biochemically shown here
5. 2008 High

   Demonstrated that VPS18 is required in engulfing cells for phagosome-lysosome fusion, extending its function beyond endosome biogenesis to corpse clearance.

   Evidence C. elegans deletion mutant analysis with fluorescence microscopy of phagosome-lysosome fusion and corpse accumulation

   PMID:18923146

   Open questions at the time

   • Tethering versus fusion contribution not separated
   • No physical partners mapped
6. 2011 Medium

   Implicated human VPS18 in viral assembly by showing it is needed for HIV-1 Gag plasma membrane targeting and infectious virion production.

   Evidence Yeast genetic screen plus siRNA knockdown of hVPS18 and VLP release assay in human cells

   PMID:21450827

   Open questions at the time

   • Direct interaction with Gag not established
   • Mechanism linking endolysosomal tethering to PM targeting unclear
7. 2012 High

   Established in mammals that VPS18 controls neuronal viability and migration by enabling multiple vesicle transport routes to the lysosome, acting upstream of β1 integrin and the degradation of Lysyl Oxidase.

   Evidence Conditional knockout mice with epistasis rescue (β1 integrin knockdown; Lox accumulation), Western blot, immunofluorescence, pathway assays

   PMID:22699122 PMID:22854957

   Open questions at the time

   • Whether VPS18 directly degrades these substrates or acts via general lysosomal failure not separated
   • Cell-autonomous mechanism of migration regulation incomplete
8. 2017 High

   Resolved the molecular basis of HOPS assembly in humans, showing VPS18's RING domain directly recruits VPS41 via a zinc-dependent RING-RING heterodimer not conserved in yeast.

   Evidence In vitro co-purification of recombinant RING domains, cell co-IP, and domain truncation/mutagenesis

   PMID:28931724

   Open questions at the time

   • Full HOPS subunit arrangement not solved structurally
   • Functional consequence of the RING-RING interaction for tethering not directly tested
9. 2019 Medium

   Revealed a moonlighting E3 ubiquitin ligase activity for VPS18 that modulates signaling pathways, with PELP1 identified as a substrate restraining ERα activation.

   Evidence Overexpression and ubiquitination assays, co-IP, and Wnt/ERα/NF-κB signaling readouts

   PMID:31015428

   Open questions at the time

   • Relies on overexpression; endogenous ligase activity not quantified
   • Catalytic residues and substrate range not fully mapped
10. 2024 Medium

    Showed VPS18 stabilizes PD-L1 through endosomal interaction, glycosylation, and trans-Golgi recycling, defining a druggable axis linking VPS18 to antitumor immunity.

    Evidence Co-IP, VPS18 knockdown/knockout, Western blot for glycosylation/stability, pharmacological inhibition (RDN), in vivo tumor models

    PMID:39413192

    Open questions at the time

    • Direct versus complex-mediated PD-L1 engagement unresolved
    • Inhibitor selectivity for VPS18 not fully characterized
11. 2025 High

    Defined opposing roles in cancer and infection: VPS18 suppresses lung tumorigenesis via lysosomal degradation of EGFR, and protects against M. tuberculosis by maintaining phagosomal membrane integrity.

    Evidence Conditional KO in LSL-K-Ras mice with dnEGFR epistasis; genome-wide CRISPR screen with KO macrophage colocalization, integrity and bacterial growth assays

    PMID:39888996 PMID:40615043

    Open questions at the time

    • Mechanism by which VPS18 preserves phagosomal membrane integrity unknown
    • Whether EGFR degradation is direct HOPS cargo handling or ligase-dependent not separated
12. 2026 High

    Linked VPS18 to human hematopoietic disease, showing its loss destabilizes HOPS/CORVET, blocks autophagic flux and neutrophil maturation, with a patient stop-gain mutation presenting as neutropenia.

    Evidence CRISPR Hoxb8 cells, iPSC differentiation, TEM, Western blot (LC3B-II, p62), zebrafish heterozygotes, patient mutation analysis

    PMID:41526335

    Open questions at the time

    • Causality of the patient variant not formally proven by rescue
    • Why neutrophil lineage is selectively vulnerable not explained

• How VPS18's tethering, RING-mediated assembly, and E3 ligase activities are coordinated at distinct membranes and which functions are direct versus secondary to general lysosomal failure remain unresolved.
• No structure of the assembled mammalian HOPS/CORVET complex
• Substrate spectrum of the ligase activity undefined
• Direct cargo recognition mechanisms for EGFR, PD-L1, and Lox not established