Affinage

WDR81

WD repeat-containing protein 81 · UniProt Q562E7

Length
1941 aa
Mass
211.7 kDa
Annotated
2026-06-11
16 papers in source corpus 10 papers cited in narrative 10 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

WDR81 is a multi-domain endolysosomal protein that governs the maturation and degradative capacity of the endosome-lysosome system and selective autophagy of aggregated proteins (PMID:27126989, PMID:28404643). It functions in a complex with WDR91 to drive endolysosomal fusion and cargo delivery to cathepsin-active lysosomes; loss of WDR81 swells early and late endosomes and blocks degradation of cargo such as tetherin and EGF-stimulated EGFR (PMID:27126989). Mechanistically, WDR81 suppresses endosomal PtdIns3P synthesis by restraining class III PI3K assembly, and its loss elevates PtdIns3P, retains the PtdIns3P-binding effector SARA on endosomes, and hyperactivates SARA-dependent TGFβ signaling, impairing adult hippocampal neurogenesis (PMID:30531936). In selective autophagy, WDR81 engages the cargo receptor p62/SQSTM1 to recognize ubiquitinated proteins and recruits LC3C through LIR motifs in its BEACH domain, while its WD40 domain binds the ATG5-ATG12 conjugate to deliver autophagic machinery onto protein aggregates; loss of WDR81 causes accumulation of ubiquitinated proteins and p62 bodies in neurons and worsens aggregate-induced neurodegeneration (PMID:28404643, PMID:33730050). This endosomal maturation function is also exploited by late-penetrating viruses, which require WDR81 to transit through late endosomes (PMID:35320319). Mutations in WDR81 impair mitotic progression in neural progenitors (PMID:28969387), and an MFS-domain missense mutation causes Purkinje cell and photoreceptor degeneration with aberrant mitochondrial morphology (PMID:23595742).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2013 Medium

    Established WDR81 as a gene whose disruption causes neurodegeneration, providing the first in vivo causal link and a candidate subcellular site of action.

    Evidence ENU mutant mouse with MFS-domain L1349P mutation, transgenic rescue, immunoelectron microscopy and mitochondrial fractionation

    PMID:23595742

    Open questions at the time
    • Mitochondrial localization not reconciled with later endolysosomal role
    • Molecular function of the MFS domain undefined
    • Mechanism linking mutation to mitochondrial spheroid morphology unknown
  2. 2016 High

    Defined the core endolysosomal function of WDR81 by showing it acts with WDR91 to drive endosome maturation and fusion required for cargo degradation.

    Evidence Forward genetic screen in haploid KBM7 cells, KO cell lines, endosomal morphology, receptor degradation and dextran-to-lysosome assays

    PMID:27126989

    Open questions at the time
    • Biochemical mechanism of how the WDR81-WDR91 complex promotes fusion not resolved
    • Direct membrane or lipid targets not identified
  3. 2017 High

    Connected WDR81 to selective autophagy of ubiquitinated proteins by mapping its interactions with p62 and LC3C and demonstrating neuronal aggregate accumulation on loss.

    Evidence Reciprocal Co-IP, BEACH-domain LIR motif mutagenesis, KO mice, brain histology

    PMID:28404643

    Open questions at the time
    • How endosomal and aggrephagy functions are coordinated unclear
    • Stoichiometry and order of p62/LC3C engagement not established
  4. 2017 Medium

    Revealed a conserved requirement for WDR81 in mitotic progression of neural progenitors, broadening its role beyond trafficking.

    Evidence Patient fibroblast mitotic index, Drosophila neural stem cell RNAi, whole-exome sequencing

    PMID:28969387

    Open questions at the time
    • Molecular mechanism linking WDR81 to prometaphase/metaphase transition unknown
    • Whether mitotic role is downstream of endosomal function untested
  5. 2018 High

    Placed WDR81 in a defined lipid-signaling pathway by showing it suppresses endosomal PtdIns3P to restrain SARA-TGFβ signaling and support neurogenesis.

    Evidence Conditional KO mice, PtdIns3P measurement, SARA localization, epistasis rescue with PI3K-III and TGFβ inhibitors, behavioral testing

    PMID:30531936

    Open questions at the time
    • Direct mechanism of class III PI3K inhibition by WDR81 not shown
    • Whether PtdIns3P regulation and WDR91 complex function are the same activity unresolved
  6. 2021 High

    Refined the aggrephagy mechanism by mapping domain contributions and demonstrating cross-species rescue of aggregate-induced neuron loss.

    Evidence Domain deletion/mutagenesis, Co-IP with ATG5-ATG12, C. elegans loss-of-function and rescue, HD patient fibroblasts, neuron viability assays

    PMID:33730050

    Open questions at the time
    • How WD40-ATG5-ATG12 binding integrates with LIR-mediated LC3C recruitment unclear
    • Quantitative contribution of aggrephagy to neuroprotection in vivo undefined
  7. 2021 Low

    Linked WDR81 to exosome biogenesis, consistent with its role as a negative regulator of class III PI3K.

    Evidence siRNA knockdown in U87-MG glioblastoma cells, exosome quantification, qRT-PCR, MTT assay

    PMID:33954857

    Open questions at the time
    • Single-method siRNA study without mechanistic dissection
    • Causal link between PI3K regulation and exosome output not directly proven
  8. 2022 High

    Demonstrated that WDR81-dependent endosome maturation is co-opted by late-penetrating viruses requiring late-endosomal transit.

    Evidence Genome-wide CRISPR-Cas9 KO screen, human WDR81 complementation, reovirus/VSV/VSV-EBO GP infection and endosomal trafficking assays

    PMID:35320319

    Open questions at the time
    • Whether viral and physiological cargo use identical WDR81 maturation step not dissected
    • Specific molecular interactors at the dead-end compartment unidentified
  9. 2025 Medium

    Connected endosomal WDR81 to apoptosis control by showing it represses IKK-NFκB pro-survival gene expression.

    Evidence WDR81 KO cells, gene expression analysis, IKK inhibitor epistasis, apoptosis assays with multiple agonists

    PMID:41042063

    Open questions at the time
    • Direct molecular link between endosomal WDR81 and the IKK complex not defined
    • Single-lab study without independent confirmation
  10. 2025 Low

    Began placing WDR81 within a lysosomal adaptor network through a conserved motif-mediated interaction with TMEM55B.

    Evidence Co-IP, TBM motif mutational analysis, reference TMEM55B-RILPL1 crystal structure (preprint)

    PMID:bio_10.1101_2025.08.19.670962

    Open questions at the time
    • Preprint, single Co-IP/mutational evidence
    • Functional consequence of WDR81-TMEM55B interaction not characterized
    • Reciprocal validation absent

Open questions

Synthesis pass · forward-looking unresolved questions
  • How WDR81's distinct activities — endosome maturation/fusion with WDR91, suppression of class III PI3K/PtdIns3P, aggrephagy, mitotic progression, and IKK-NFκB repression — are mechanistically unified by its BEACH/MFS/WD40 architecture remains unresolved.
  • No structural model of full-length WDR81 or its domain interplay
  • Whether one biochemical activity underlies all phenotypes is untested
  • Direct enzymatic substrate or lipid target unidentified

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2 GO:0098772 molecular function regulator activity 1
Localization
GO:0005768 endosome 3 GO:0005764 lysosome 2
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-5653656 Vesicle-mediated transport 2 R-HSA-9612973 Autophagy 2
Complex memberships
WDR81-WDR91 complex

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2017 WDR81 interacts with the autophagy cargo receptor p62 (SQSTM1) and facilitates recognition of ubiquitinated proteins by p62. WDR81 also interacts with LC3C through canonical LIR (LC3-interacting region) motifs located in the BEACH domain, promoting LC3C recruitment to ubiquitinated protein aggregates. Loss of WDR81 causes accumulation of ubiquitinated proteins and p62 bodies, and WDR81 inactivation in mice causes accumulation of p62 bodies in cortical and striatal neurons. Co-immunoprecipitation, loss-of-function (KO mice, cell-based), LIR motif mutagenesis, immunofluorescence, mouse brain histology The Journal of cell biology High 28404643
2017 WDR81 mutations in patients and Drosophila WDR81 ortholog knockdown both result in increased mitotic index and delayed prometaphase/metaphase transition in neural progenitor/stem cells, indicating a conserved role for WDR81 in mitotic progression. Patient fibroblast analysis (mitotic index measurement), Drosophila RNAi knockdown of WDR81 ortholog in neural stem cells, whole-exome sequencing of patients Brain : a journal of neurology Medium 28969387
2016 WDR81 functions in a complex with WDR91 to regulate endolysosomal trafficking. Loss of WDR81 results in swollen endolysosomal compartments (enlarged early and late endosomes), reduced delivery of endocytosed cargo to cathepsin-active lysosomes, and impaired degradation of tetherin (BST2) and EGF-stimulated EGFR. The WDR81-WDR91 complex is required for fusion of endolysosomal compartments. Forward genetic screen (haploid KBM7 cells), KO cell lines, endosomal morphology analysis, receptor degradation assays, dextran trafficking to lysosomes Traffic (Copenhagen, Denmark) High 27126989
2018 WDR81 suppresses endosomal PtdIns3P (PI3P) synthesis, likely by inhibiting assembly of the class III PI3K complex. In the absence of WDR81, elevated endosomal PtdIns3P leads to retention of the PtdIns3P-binding protein SARA on endosomes and hyperactivation of SARA-dependent TGFβ signaling, impairing adult hippocampal neurogenesis. Inhibition of PI3K-III or suppression of SARA-dependent TGFβ signaling rescues the neurogenesis defect in WDR81-deficient mice. WDR81 KO in adult neural progenitor cells (conditional ablation in mice), PtdIns3P measurement, SARA localization analysis, epistasis by PI3K-III inhibitor and TGFβ pathway inhibition, behavioral testing (hippocampus-dependent learning) Molecular psychiatry High 30531936
2013 A missense mutation L1349P in the predicted major facilitator superfamily (MFS) domain of WDR81 causes Purkinje cell degeneration and photoreceptor cell loss in mice. WDR81 localizes to mitochondria in Purkinje cell neurons (shown by immunoelectron microscopy and mitochondrial-enriched fractionation), and mutant Purkinje cell dendrites display aberrant large spheroid-like mitochondria. ENU mutant mouse characterization, transgenic rescue, immunoelectron microscopy, subcellular fractionation (mitochondria-enriched fractions), electron microscopy The Journal of neuroscience : the official journal of the Society for Neuroscience Medium 23595742
2021 WDR81's BEACH and MFS domains are sufficient for its recruitment to Huntingtin polyQ aggregates. The WD40 repeat domain of WDR81 is essential for interaction with the covalently bound ATG5-ATG12 conjugate. WDR81 facilitates recruitment of autophagic proteins onto polyQ aggregates and promotes autophagic clearance. In C. elegans, deletion of the WDR81 homolog SORF-2 causes p62 body accumulation and exacerbates α-synuclein-induced neuron loss; overexpression of SORF-2 or human WDR81 restores neuron viability. Domain deletion/mutagenesis, Co-immunoprecipitation (WDR81 with ATG5-ATG12), C. elegans loss-of-function and overexpression, fibroblasts from HD patients, primary neuron viability assays PLoS genetics High 33730050
2022 WDR81 is required for the endosomal maturation step that allows late-penetrating viruses (reovirus, VSV-EBO GP) to transit through late endosomes. WDR81 KO does not affect viral attachment or uptake into early endosomes, but causes accumulation of viral particles in dead-end compartments and impairs viral gene expression and infectious particle production. Human WDR81 complements mouse WDR81 KO cells, confirming functional conservation. CRISPR-Cas9 KO screen (>20,000 genes), complementation with human WDR81, viral infection assays (reovirus, VSV, VSV-EBO GP), endosomal trafficking analysis PLoS pathogens High 35320319
2025 WDR81 represses IKK complex-mediated activation of NFκB pro-survival gene expression. In WDR81-deficient cells, expression of several pro-survival genes is upregulated via the IKK-NFκB pathway. Blocking IKK signaling in WDR81-deficient cells restores pro-survival gene expression to normal levels and re-sensitizes cells to apoptosis triggers, revealing a link between endosomally localized WDR81 and IKK-NFκB signaling. WDR81 KO cells, gene expression analysis, IKK inhibitor epistasis, apoptosis assays with multiple agonists mBio Medium 41042063
2021 WDR81 gene silencing in U87-MG glioblastoma cells reduces exosome secretion (concentration and protein/RNA content), consistent with WDR81 acting as a negative regulator of class III PI3K activity whose loss normally suppresses autophagy and increases exosome production. siRNA knockdown, real-time qRT-PCR, exosome isolation and quantification (DLS, protein/RNA content measurement), MTT viability assay Journal of molecular neuroscience : MN Low 33954857
2025 WDR81 contains a conserved TBM (TMEM55B Binding Motif) and co-immunoprecipitates with TMEM55B, a lysosomal membrane protein, in a phospho-Rab-independent manner, placing WDR81 within a lysosomal adaptor complex centered on TMEM55B. Co-immunoprecipitation, mutational analysis of TBM motif, crystal structure of TMEM55B-RILPL1 complex as reference bioRxiv (preprint)preprint Low bio_10.1101_2025.08.19.670962

Source papers

Stage 0 corpus · 16 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 The BEACH-containing protein WDR81 coordinates p62 and LC3C to promote aggrephagy. The Journal of cell biology 62 28404643
2013 WDR81 is necessary for purkinje and photoreceptor cell survival. The Journal of neuroscience : the official journal of the Society for Neuroscience 31 23595742
2017 WDR81 mutations cause extreme microcephaly and impair mitotic progression in human fibroblasts and Drosophila neural stem cells. Brain : a journal of neurology 30 28969387
2018 WDR81 regulates adult hippocampal neurogenesis through endosomal SARA-TGFβ signaling. Molecular psychiatry 24 30531936
2016 A Genetic Screen Identifies a Critical Role for the WDR81-WDR91 Complex in the Trafficking and Degradation of Tetherin. Traffic (Copenhagen, Denmark) 23 27126989
2022 A CRISPR-Cas9 screen reveals a role for WD repeat-containing protein 81 (WDR81) in the entry of late penetrating viruses. PLoS pathogens 12 35320319
2021 Novel compound heterozygous frameshift variants in WDR81 associated with congenital hydrocephalus 3 with brain anomalies: First Chinese prenatal case confirms WDR81 involvement. Molecular genetics & genomic medicine 8 33724704
2021 WDR81 Gene Silencing Can Reduce Exosome Levels in Human U87-MG Glioblastoma Cells. Journal of molecular neuroscience : MN 8 33954857
2020 A Novel Homozygous Frameshift WDR81 Mutation associated with Microlissencephaly, Corpus Callosum Agenesis, and Pontocerebellar Hypoplasia. Journal of pediatric genetics 6 33996189
2025 Betaine enhances SCAPs chondrogenic differentiation and promotes cartilage repair in TMJOA through WDR81. Stem cell research & therapy 5 39920811
2021 Reduction of WDR81 impairs autophagic clearance of aggregated proteins and cell viability in neurodegenerative phenotypes. PLoS genetics 4 33730050
2015 Characterization of a novel zebrafish (Danio rerio) gene, wdr81, associated with cerebellar ataxia, mental retardation and dysequilibrium syndrome (CAMRQ). BMC neuroscience 4 27390838
2025 WDR81 represses IKK-mediated expression of pro-survival genes to regulate apoptosis. mBio 1 41042063
2024 Expression of Autophagy-Related Proteins in Microlissencephaly Associated with a Novel Variant in the WDR81 Gene. Molecular syndromology 1 39911170
2021 Fetal brain arrest broadens the spectrum of WDR81-related developmental brain malformations. Neurogenetics 1 34338917
2025 WDR81 Mutation in Two Siblings: A Case Report and Review of Literature. Molecular syndromology 0 41245233

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