WDR73

WDR73 is a WD40-repeat protein that localizes diffusely in the cytoplasm during interphase and relocalizes to spindle poles and astral microtubules during mitosis, where it interacts with α-, β-, and γ-tubulin, HSP70/90, and the CAD multi-enzyme complex to support cell cycle progression and cell survival (PMID:25466283, PMID:26070982). WDR73 also physically associates with Integrator complex subunits INTS9 and INTS11, and its depletion disrupts UsnRNA 3′-end processing and the transcriptional response to EGF stimulation (PMID:33686175). WDR73 directly binds PIP4K2C and stabilizes it via the autophagy-lysosomal pathway, maintaining PIP2 levels required for focal adhesion formation in podocytes; podocyte-specific Wdr73 knockout in mice causes albuminuria and foot process effacement (PMID:36290302). Loss-of-function mutations in WDR73 cause Galloway-Mowat syndrome, characterized by nephrotic syndrome and neurodevelopmental defects including impaired brain morphogenesis (PMID:25466283, PMID:25873735).

1. 2014 Medium

   Establishing that WDR73 is a mitotic spindle-associated protein whose loss causes nuclear morphology defects and reduced viability resolved the first mechanistic question: where does the protein act and what happens without it?

   Evidence Immunofluorescence and subcellular fractionation in patient fibroblasts and siRNA-depleted podocytes

   PMID:25466283

   Open questions at the time

   • No direct binding partner identified at this stage
   • Mechanism linking spindle localization to nuclear morphology defects not defined
   • Single-lab observation without independent replication
2. 2015 Medium

   Identification of WDR73's physical interactome — tubulins, HSP70/90, and the CAD complex — and demonstration that disease-causing truncations destabilize the protein and dysregulate chaperone engagement established the molecular basis of loss-of-function pathogenesis.

   Evidence Co-immunoprecipitation and pull-down assays with endogenous and recombinant wild-type and mutant WDR73 proteins; patient fibroblast proliferation and senescence assays

   PMID:26070982

   Open questions at the time

   • Functional significance of the WDR73–CAD interaction is unexplored
   • No structural model to explain how WD40 repeats engage tubulins versus chaperones
   • Cell cycle arrest mechanism not molecularly defined
3. 2015 Medium

   Demonstration that wdr73 knockdown in zebrafish causes midbrain and cerebellar morphogenesis defects established an in vivo developmental requirement and linked WDR73 to the neurological component of Galloway-Mowat syndrome.

   Evidence Morpholino knockdown in zebrafish embryos with brain morphology phenotyping

   PMID:25873735

   Open questions at the time

   • Morpholino off-target effects not fully excluded (no genetic mutant confirmation)
   • Downstream signaling pathways mediating brain defects not identified
   • Kidney phenotype not assessed in the zebrafish model
4. 2021 Medium

   Discovery that WDR73 interacts with Integrator subunits INTS9/INTS11 and is required for UsnRNA processing and EGF-responsive transcription revealed a nuclear RNA-processing function orthogonal to its mitotic role.

   Evidence Co-immunoprecipitation of WDR73 with INTS9/INTS11; snRNA processing assays and EGF-response transcriptomics in WDR73-depleted cells

   PMID:33686175

   Open questions at the time

   • Whether WDR73 is a stable Integrator complex subunit or a transient accessory factor is unresolved
   • Relative contribution of snRNA processing versus transcription defects to disease phenotype unknown
   • Single-lab finding without independent replication
5. 2022 Medium

   Identification of PIP4K2C as a direct WDR73 binding partner whose stability depends on WDR73-mediated protection from autophagy-lysosomal degradation provided a mechanism for podocyte injury: reduced PIP2 and impaired focal adhesion formation.

   Evidence Protein microarray screen, GST pulldown, WDR73 KO HEK293 cells, and podocyte-specific Wdr73 conditional knockout mice with focal adhesion, PIP2, and proteinuria readouts

   PMID:36290302

   Open questions at the time

   • Structural basis of the WDR73–PIP4K2C interaction not determined
   • Whether PIP4K2C stabilization accounts for neurological phenotypes is untested
   • Relationship between the PIP4K2C and Integrator pathways not explored

• How WDR73's multiple functions — mitotic spindle association, Integrator-mediated RNA processing, and PIP4K2C stabilization — are coordinated, and which function(s) primarily drive the neuronal versus podocyte pathology in Galloway-Mowat syndrome, remains unresolved.
• No structural model of WDR73 or its complexes exists
• Relative contribution of each pathway to neuronal versus renal disease is unknown
• No neuron-specific conditional knockout model has been reported