WDR74

WDR74 (yeast Nsa1) is an essential nucleolar WD40-domain protein that acts as a pre-60S ribosome biogenesis factor coordinating early pre-rRNA processing during large ribosomal subunit assembly (PMID:29107693, PMID:39840464). It functions within a discrete pre-ribosomal subcomplex—the 'WDR74 module' comprising WDR74, RPF1, MAK16, and RRP1—in which each component is mutually required for association with the MTR4-nuclear exosome complex and for accurate ITS1 cleavage in the 60S pathway (PMID:39706051, PMID:29107693). WDR74 is released from the MTR4-exosome complex by the AAA-ATPase NVL2 (yeast Rix7) in an ATP-hydrolysis-dependent manner; blocking this release with ATPase-deficient NVL2 retains WDR74 on MTR4, mislocalizes it to the nucleoplasm, and prevents MTR4 from recruiting the adaptor PICT1 required for 3'-end maturation of 5.8S rRNA (PMID:18559667, PMID:26456651, PMID:39706051). The full-length architecture of the protein comprises an N-terminal WD40 domain and a disordered C-terminus (PMID:29364241). Loss of WDR74 reduces 60S subunit levels and large-subunit ribosomal proteins, arrests cells beyond the morula stage, and activates Trp53-dependent apoptosis that can be rescued by blocking Trp53 (PMID:21799883, PMID:39840464). Beyond ribosome biogenesis, WDR74 acts as a coactivator of TGF-β/Smad signaling through direct interaction with Smad2/3, enhancing their phosphorylation and nuclear accumulation (PMID:30594465, PMID:35982296); promotes Wnt/β-catenin signaling by reducing β-catenin phosphorylation and driving its nuclear accumulation (PMID:31838084, PMID:34553072); and controls the RPL5-MDM2-p53 axis to stabilize or destabilize p53, influencing apoptosis and ferroptosis in cancer contexts (PMID:32005977, PMID:40959275).

1. 2008 High

   Established the regulated dissociation step at the heart of WDR74 function—that an AAA-ATPase actively releases Nsa1 from a late pre-60S particle—defining Nsa1 as a transiently associated assembly factor rather than a structural ribosome component.

   Evidence Genetic epistasis, fluorescence localization, and co-IP in yeast rix7 mutants

   PMID:18559667

   Open questions at the time

   • Did not define the molecular signal triggering release
   • Yeast ortholog; human relevance not yet tested
   • No structural basis for the Rix7-Nsa1 interaction
2. 2011 High

   Placed WDR74 upstream of Trp53-dependent apoptosis in development by showing its loss arrests embryos and globally reduces Pol I/II/III transcripts, with p53 blockade rescuing the phenotype.

   Evidence RNAi knockdown in mouse preimplantation embryos with Trp53 rescue and RT-qPCR

   PMID:21799883

   Open questions at the time

   • Did not establish the direct molecular link between WDR74 loss and p53 activation
   • Global transcript reduction could be secondary to general nucleolar stress
3. 2013 High

   Mapped Nsa1 into a genetic pathway with Mak5, Nop1, and Nop4, refining where in 60S assembly the factor acts and showing Rix7 has substrates beyond Nsa1.

   Evidence Bypass suppressor and synthetic lethality screens, co-IP, dominant-negative analysis in yeast

   PMID:24312670

   Open questions at the time

   • Genetic interactions do not establish direct physical contacts
   • Additional Rix7 substrates left unidentified
4. 2015 High

   Translated the yeast model to human cells, identifying WDR74 as a component of the MTR4-exosome complex released by NVL2 ATPase activity, with knockdown reducing 60S levels.

   Evidence Mass-spectrometry proteomics, co-IP, ATPase-deficient NVL2 mutant, siRNA with ribosome fractionation

   PMID:26456651

   Open questions at the time

   • Did not resolve the specific rRNA processing step affected
   • Stoichiometry within the MTR4-exosome complex unknown
5. 2017 High

   Pinpointed the molecular defect as failure of early ITS1 pre-rRNA cleavage and linked NVL2-blocked WDR74 release to nucleoplasmic mislocalization and the same processing defect.

   Evidence siRNA with Northern blot pre-rRNA analysis, ATPase-deficient NVL2, proximity ligation assay, fractionation

   PMID:29107693

   Open questions at the time

   • Did not identify the nuclease executing ITS1 cleavage
   • Whether WDR74 acts catalytically or as a scaffold unresolved
6. 2018 High

   Provided the full-length structural model of Nsa1, defining an N-terminal WD40 domain and a disordered C-terminus that together explain its quaternary organization.

   Evidence Hybrid X-ray crystallography (WD40 domain) and SAXS with ab initio/rigid-body modeling on recombinant protein

   PMID:29364241

   Open questions at the time

   • No structure of WDR74 within the pre-60S particle or MTR4 complex
   • Function of the disordered C-terminus not defined
7. 2018 Medium

   Revealed a moonlighting role outside ribosome biogenesis, identifying WDR74 as a Smad coactivator that directly binds Smad2/3 and enhances their phosphorylation and nuclear accumulation.

   Evidence Co-IP, Western blot for Smad2/3 phosphorylation, nuclear fractionation, TGF-β reporter gain/loss-of-function

   PMID:30594465

   Open questions at the time

   • Mechanism by which a nucleolar factor enhances Smad phosphorylation unclear
   • Direct interaction not validated by reciprocal or structural methods
8. 2019 Medium

   Connected WDR74 to Wnt/β-catenin signaling, showing it drives nuclear β-catenin accumulation and tumor-promoting phenotypes in lung cancer.

   Evidence Overexpression/knockout, Western blot, Wnt reporter assays, xenograft model

   PMID:31838084

   Open questions at the time

   • Did not define how WDR74 affects β-catenin stability mechanistically
   • Direct versus indirect action on the pathway unresolved
9. 2020 Medium

   Defined a ribosomal-protein-mediated route to p53 control, showing WDR74 modulates RPL5 to restrain MDM2 and protect p53 from degradation in melanoma.

   Evidence iTRAQ proteomics, gain/loss-of-function, ubiquitination Western blots, xenograft and metastasis models

   PMID:32005977

   Open questions at the time

   • Directionality of p53 regulation appears context-dependent across cancers
   • Whether RPL5 modulation reflects general ribosome biogenesis disruption unclear
10. 2022 Medium

    Extended the TGF-β/Smad coactivator role to macrophage biology and tissue repair, with pharmacological receptor blockade reversing WDR74-driven effects.

    Evidence Co-IP, gain/loss-of-function, Western blot, immunofluorescence, LY2109761 rescue in a mouse DFU model

    PMID:35982296

    Open questions at the time

    • Does not distinguish direct coactivation from broader transcriptional effects
    • Single-lab confirmation of WDR74-Smad2/3 interaction
11. 2024 High

    Defined the 'WDR74 module' (WDR74-RPF1-MAK16-RRP1) as a mutually dependent unit required for MTR4 association and showed NVL2-mediated release enables MTR4 recruitment of PICT1 for 5.8S rRNA 3'-end maturation.

    Evidence Co-IP/MS, siRNA, pre-rRNA processing analysis, interaction mapping

    PMID:39706051

    Open questions at the time

    • Structural organization of the module within pre-60S not resolved
    • Order of assembly and release events not fully mapped
12. 2024 Medium

    Identified upstream transcriptional control of WDR74 by ATF5, itself regulated by METTL14-mediated m6A, linking WDR74 expression to β-catenin-driven stemness in gastric cancer.

    Evidence ChIP for ATF5 promoter binding, MeRIP-qPCR, Western blot, rescue assays

    PMID:39497511

    Open questions at the time

    • Does not address whether WDR74's ribosomal function contributes to stemness
    • Single-lab regulatory axis
13. 2025 High

    Confirmed in a CRISPR-knockout embryo model that WDR74 loss selectively impairs 60S biogenesis, reducing large-subunit proteins (RPL24, RPL26) but not small-subunit proteins, and blocks cell division beyond the morula stage.

    Evidence CRISPR-Cas9 knockout, label-free quantitative proteomics, division phenotyping

    PMID:39840464

    Open questions at the time

    • Does not establish whether division arrest is purely ribosome-dependent or via p53
    • Mechanism of selective large-subunit protein loss not defined
14. 2025 Medium

    Showed WDR74 modulates the p53-MDM2 interaction to promote p53 ubiquitination and degradation, inhibiting ferroptosis in hepatocellular carcinoma, with CAPG acting as an upstream transcriptional driver.

    Evidence Co-IP, ubiquitination assays, ChIP-seq, RNA-seq, gain/loss-of-function, xenograft

    PMID:40959275

    Open questions at the time

    • p53 outcome opposite to the melanoma RPL5-MDM2 model, context dependence unexplained
    • Direct versus indirect effect on the p53-MDM2 interface not resolved
15. 2025 Medium

    Revealed cis/trans transcriptional regulation of WDR74 by the adjacent lncRNA SNHG1, which recruits EWSR1 to the WDR74 promoter in osteosarcoma.

    Evidence ChIP-qPCR for EWSR1 binding, RNA pulldown, RIP, actinomycin D stability assay

    PMID:40510136

    Open questions at the time

    • Does not link this regulation to WDR74's downstream ribosomal or signaling functions
    • Single-lab regulatory mechanism

• It remains unresolved how WDR74's core nucleolar ribosome biogenesis function mechanistically connects to its reported roles in TGF-β/Smad, Wnt/β-catenin, and p53/MDM2 signaling, and whether the cancer-context signaling roles are direct or downstream consequences of perturbed ribosome assembly.
• No unified mechanism linking nucleolar and signaling functions
• Opposite p53 directionality across cancer models unexplained
• No structure of WDR74 engaged with signaling partners