WDR73

WDR73 is a WD40-repeat protein required for the maintenance of cell architecture, cell cycle progression, and survival in neurons and podocytes (PMID:25466283, PMID:25873735). It localizes diffusely in the cytoplasm during interphase and relocalizes to spindle poles and astral microtubules in mitosis, where it physically associates with α-, β-, and γ-tubulin, HSP-70/HSP-90, and the CAD multi-enzyme complex; its depletion disrupts the microtubule network, distorts nuclear morphology, and reduces cell viability (PMID:25466283, PMID:26070982). Disease-associated truncating mutants are unstable and bind tubulin and the chaperones more avidly, indicating loss of normal WDR73 stability and microtubule association (PMID:26070982). Beyond the mitotic cytoskeleton, WDR73 interacts with the Integrator complex subunits INTS9 and INTS11 and is required for Integrator-dependent UsnRNA processing and the EGF-stimulated transcriptional response, with its loss perturbing cell-cycle regulatory gene expression (PMID:33686175). WDR73 also binds the phospholipid kinase PIP4K2C and stabilizes it against autophagy-lysosomal degradation, sustaining PIP2 levels and focal adhesion formation; podocyte-specific Wdr73 knockout mice develop albuminuria and foot-process injury (PMID:36290302). Loss of WDR73 in zebrafish causes brain growth and morphogenesis defects, establishing a developmental requirement consistent with its podocyte and neuronal roles (PMID:25873735).

1. 2014 Medium

   Established that WDR73 is a cell-cycle-regulated cytoskeletal protein whose loss compromises cell integrity, framing it as more than a static structural component.

   Evidence Immunofluorescence localization across cell cycle, patient fibroblast analysis, and WDR73-depleted podocyte assays

   PMID:25466283

   Open questions at the time

   • Direct binding partners at the spindle not yet identified
   • Mechanism linking microtubule association to nuclear morphology unresolved
2. 2015 Medium

   Defined the molecular interactome of WDR73 at mitotic microtubules and showed disease mutants are unstable, connecting protein destabilization to aberrant tubulin/chaperone binding.

   Evidence Co-immunoprecipitation/interaction assays with recombinant wild-type and truncated proteins; fibroblast proliferation assays

   PMID:26070982

   Open questions at the time

   • Functional consequence of CAD complex association not established
   • Whether tubulin binding is direct or chaperone-mediated unclear
3. 2015 Medium

   Demonstrated an organismal requirement for WDR73 in vertebrate brain development, linking molecular dysfunction to the neurological phenotype.

   Evidence Morpholino knockdown in zebrafish with morphological readout of midbrain/cerebellum

   PMID:25873735

   Open questions at the time

   • Cell-type and molecular basis of brain defect not dissected
   • Morpholino specificity not cross-validated by mutant
4. 2021 Medium

   Revealed a nuclear/transcriptional axis for WDR73 through the Integrator complex, expanding its role beyond the cytoskeleton to RNA processing and signal-responsive transcription.

   Evidence Co-immunoprecipitation with INTS9/INTS11, snRNA processing assays, EGF transcriptional assays, and transcriptomics of suppressed cells

   PMID:33686175

   Open questions at the time

   • How WDR73 mechanistically contributes to Integrator activity unknown
   • Relationship between cytoplasmic and Integrator-associated pools unresolved
5. 2022 High

   Identified a substrate-stabilization mechanism whereby WDR73 protects PIP4K2C from autophagy-lysosomal degradation to maintain PIP2 and focal adhesions, providing a molecular route to the podocyte phenotype in vivo.

   Evidence Protein microarray and GST pulldown, WDR73 KO HEK293 cells, conditional knockout mice with ADR nephropathy, and primary podocyte focal adhesion assays

   PMID:36290302

   Open questions at the time

   • How WDR73 shields PIP4K2C from autophagic turnover at the molecular level unknown
   • Integration of the PIP4K2C/FA axis with the mitotic and Integrator functions not established

• It remains unknown how WDR73's distinct activities — mitotic microtubule association, Integrator-dependent RNA/transcription regulation, and PIP4K2C stabilization — are coordinated into a single unifying biochemical function.
• No structural model of WDR73 or its complexes
• No defined catalytic or scaffolding mechanism unifying the three pathways
• Causal hierarchy among the phenotypes not determined