DNAI3

WDR63 (DNAI3) is a WD40-repeat protein that functions as an intermediate chain of the vertebrate inner dynein arm (IDA), the Dynein-f complex that powers ciliary and flagellar motility (PMID:30060180). As the vertebrate orthologue of Chlamydomonas IC140, it associates with the IDA subunits WDR78 (IC138 orthologue) and the heavy chain DNAH2, and is expressed specifically in motile cilia-bearing cells; unlike its algal counterpart, vertebrate Dynein-f is essential for ciliary beat, as its depletion paralyzes mouse ependymal cilia (PMID:30060180). WDR63 binds WDR78 primarily through its WD40-repeat domain and is required for IDA assembly in sperm flagella, where loss of function produces disorganized '9+2' axonemes lacking IDAs and male infertility (PMID:34782613), and it further bridges to cytoplasmic dynein 2 trafficking machinery through TCTEX1D2 during flagellum formation (PMID:39827215). Beyond the axoneme, WDR63 is a transcriptional target of p53 that acts downstream of p53 to suppress cell migration, invasion, and metastasis by directly binding the Arp2/3 complex and inhibiting branched actin polymerization (PMID:32128961). WDR63 also participates in human disease beyond cilia: an in-frame deletion removing WD-repeat domains acts as a dominant-negative/gain-of-function allele causing neural tube and encephalocele malformations modeled in zebrafish (PMID:29285825), and WDR63 promotes K63-linked while reducing K48-linked polyubiquitination of p53 to stabilize it and drive pulmonary fibrosis (PMID:41640377). A CRISPR knockout in human airway epithelium additionally implicates WDR63 in an intracellular post-nuclear-entry step of rAAV vector transduction (PMID:37966249, PMID:37808760).

1. 2014 Low

   Before any molecular partner was known, WDR63 was first linked to a cellular process through a functional screen identifying it as a positive regulator of stem cell osteogenic differentiation.

   Evidence Gain/loss-of-function in SCAPs with mineralization and osteogenic marker readouts, in vivo nude mouse transplantation, H3K4Me3 ChIP-on-chip

   PMID:25498833

   Open questions at the time

   • No molecular mechanism or binding partner identified
   • Single lab, functional readouts only
   • No connection drawn to ciliary or dynein function
2. 2018 Medium

   A human in-frame deletion plus zebrafish modeling established that WDR63 disruption causes neural tube/encephalocele malformations and that loss of specific WD-repeat domains can act as a dominant-negative allele.

   Evidence CRISPR/Cas9 somatic deletion and RNA overexpression in zebrafish, whole-genome sequencing of human fetus

   PMID:29285825

   Open questions at the time

   • Molecular mechanism of malformation unresolved
   • Whether developmental role reflects ciliary defects not established
   • Single lab
3. 2019 High

   WDR63 was defined as the vertebrate orthologue of IC140 and an intermediate chain of the inner dynein arm Dynein-f, answering what protein complex it belongs to and showing the complex is essential for vertebrate ciliary beat.

   Evidence Reciprocal Co-IP with Dnah2 and Wdr78, RNAi in mouse ependymal cells, zebrafish morpholino knockdown, immunofluorescence

   PMID:30060180

   Open questions at the time

   • Structural arrangement within the dynein arm not resolved
   • Mechanism by which Dynein-f drives beat not detailed
4. 2020 High

   An unexpected non-ciliary role was established: WDR63 is a p53 transcriptional target that inhibits Arp2/3-mediated branched actin polymerization to suppress migration and metastasis.

   Evidence ChIP/reporter assays, Co-IP with Arp2/3, in vitro actin polymerization reconstitution, migration/invasion assays, mouse xenografts

   PMID:32128961

   Open questions at the time

   • Structural basis of Arp2/3 inhibition not defined
   • Single lab
   • Relationship between cytoskeletal/actin role and axonemal role unclear
5. 2021 High

   The WDR63–WDR78 interaction was mapped to the WD40 domain and shown to be required for inner dynein arm assembly in sperm flagella, defining the structural basis of axonemal function and a male infertility phenotype.

   Evidence Reciprocal Co-IP identifying interaction domain, CRISPR-Cas9 knockout mice, transmission electron microscopy of axoneme ultrastructure, human patient cohort

   PMID:34782613

   Open questions at the time

   • Order of assembly steps within the IDA not resolved
   • How WD40 domain engages WDR78 structurally not determined
6. 2023 Medium

   A genome-wide screen placed WDR63 in an intracellular post-nuclear-entry step of rAAV transduction, separating its role from vector internalization and nuclear import.

   Evidence Genome-wide CRISPR screen with individual KO validation in polarized human airway epithelium; transduction, internalization, and nuclear entry assays

   PMID:37808760 PMID:37966249

   Open questions at the time

   • Precise trafficking/uncoating step not identified
   • Mechanistic link to WDR63's dynein or actin functions not established
7. 2025 Medium

   WDR63 was positioned in a network bridging cytoplasmic dynein 2 and the axonemal inner dynein arm via TCTEX1D2 during flagellum formation.

   Evidence Co-IP in mouse testes (TCTEX1D2 pulled down WDR63 and WDR78), Tctex1d2 knockout mice

   PMID:39827215

   Open questions at the time

   • Single Co-IP; placement inferred via TCTEX1D2 KO rather than WDR63 manipulation
   • Functional dependency of WDR63 on TCTEX1D2 not directly tested
8. 2026 Medium

   WDR63 was shown to control p53 protein stability through ubiquitin chain editing—promoting K63-linked while reducing K48-linked polyubiquitination—linking it to pulmonary fibrosis.

   Evidence MS/Co-IP identifying p53 as substrate, linkage-specific ubiquitination assays, overexpression/silencing, bleomycin-induced mouse fibrosis model

   PMID:41640377

   Open questions at the time

   • Whether WDR63 has intrinsic E3 ligase activity or acts as an adaptor not established
   • Single lab
   • Reconciliation with the 2020 finding that p53 induces WDR63 (feedback architecture) not resolved
9. 2026 Low

   WDR63 was linked to vimentin binding, DRP1 upregulation, and mitochondrial fission promoting chondrogenic differentiation in stem cells.

   Evidence Co-IP and co-localization with VIM, Western blot for DRP1/chondrogenic markers, gain/loss-of-function in SCAPs, rabbit osteochondral defect model

   PMID:41796360

   Open questions at the time

   • Single Co-IP/co-localization from one lab; mitochondrial fission link inferred from DRP1 levels without direct reconstitution
   • Direct VIM binding not validated reciprocally
   • Mechanistic connection to other WDR63 functions absent

• How a single WD40 protein integrates its axonemal dynein-assembly role with its cytosolic actin/Arp2/3, p53-ubiquitin, and trafficking activities—and whether these are independent moonlighting functions or one mechanism—remains unresolved.
• No structural model unifying WD40-mediated interactions across complexes
• Tissue-specific partner switching not characterized
• Whether non-ciliary roles depend on the dynein-arm interaction unknown