PRICKLE3

PRICKLE3 is a LIM-domain protein and core component of the planar cell polarity (PCP) machinery that controls the asymmetric distribution of polarity complexes during vertebrate morphogenesis (PMID:27658614, PMID:9344658). It forms membrane-localized complexes with VANGL1/2 that polarize to anterior cell edges in response to instructive Wnt5a/Wnt11 ligands, orienting away from Wnt sources (PMID:27658614), and it stabilizes VANGL proteins at the cell surface by protecting them from CK1ε-mediated phosphorylation and antagonizing the CK1ε–RNF43 interaction to limit RNF43-dependent ubiquitination and degradation—an activity specific to PRICKLE3 and not PRICKLE1 (PMID:41455754). Apical localization of PRICKLE3 is established by physical association with Par3 (PMID:30256191), while Frizzled3-dependent phosphorylation of Vangl2 negatively regulates Vangl2–PRICKLE3 complex formation and is required for proper polarization (PMID:34806749). Through these complexes PRICKLE3 drives multiciliated cell intercalation and ciliogenesis, including recruitment of γ-tubulin and Nedd1 to the basal body in cooperation with Wtip (PMID:26079437, PMID:27062996). Independently of its PCP role, PRICKLE3 localizes to mitochondria where it binds the ATP synthase subunit ATP8 to support ATP synthase assembly and function; the p.Arg53Trp variant impairs this and produces LHON-like retinal ganglion cell degeneration (PMID:32516135, PMID:35947995). In non-small cell lung cancer cells, PRICKLE3 recruits USP9X to deubiquitinate and stabilize DVL2, promoting canonical WNT/β-catenin signaling (PMID:40973792).

1. 1997 Medium

   Before any function was known, the gene had to be defined as a real transcribed locus encoding a LIM-domain protein, establishing the molecular entity for later study.

   Evidence Genomic sequencing, RT-PCR, Northern blot and CpG island analysis mapping LMO6/PRICKLE3 to Xp11.23

   PMID:9344658

   Open questions at the time

   • No functional or biochemical role assigned
   • Protein-level expression and localization not addressed
2. 2015 Medium

   Established that Vangl2/Prickle3 complexes operate in epithelial cell behavior, linking the protein to multiciliated cell intercalation during gastrulation and neurulation.

   Evidence Morpholino knockdown with imaging, epistasis, and KIF13B–Dishevelled Co-IP in Xenopus

   PMID:26079437

   Open questions at the time

   • Direct biochemical PRICKLE3–VANGL2 interaction not resolved here
   • Trafficking mechanism inferred rather than demonstrated
3. 2016 High

   Defined the instructive logic of PCP by showing specific Wnt ligands orient Prickle3/Vangl2 complexes, and identified Wtip as a cooperating partner directing basal-body ciliogenesis.

   Evidence Live imaging of fluorescent fusions, Wnt gain/loss-of-function in Xenopus, and Prickle3–Wtip Co-IP

   PMID:27062996 PMID:27658614

   Open questions at the time

   • Receptor-level mechanism of Wnt-directed polarization not defined
   • How Prickle3 recruits γ-tubulin/Nedd1 biochemically unresolved
4. 2018 High

   Placed Par3 upstream of PRICKLE3, answering how the protein achieves apical positioning required for asymmetric PCP complex distribution.

   Evidence Co-IP, proximity biotinylation, and dominant-negative Par3 fragment in Xenopus neural plate

   PMID:30256191

   Open questions at the time

   • Structural basis of Par3–PRICKLE3 binding unknown
   • Whether Par3 acts through VANGL or directly on PRICKLE3 not separated
5. 2020 High

   Revealed a non-PCP mitochondrial role, showing PRICKLE3 binds ATP8 to support ATP synthase biogenesis and that a point mutation causes LHON-like retinal degeneration.

   Evidence Reciprocal Co-IP, knockdown cells, and Prickle3-knockout mouse with retinal phenotyping

   PMID:32516135

   Open questions at the time

   • How a PCP membrane protein partitions to mitochondria unexplained
   • Direct effect on ATP synthase assembly intermediates not structurally resolved
6. 2021 High

   Defined phosphoregulation of the complex, showing Frizzled3-dependent Vangl2 phosphorylation disrupts Vangl2–PRICKLE3 association needed for polarization.

   Evidence Proximity biotinylation, crosslinking, and phosphomutant rescue in Xenopus; tissue transplantation establishing a dorsal-lip planar cue

   PMID:34259326 PMID:34806749

   Open questions at the time

   • Kinase acting downstream of Fz3 not identified
   • Molecular nature of the dorsal-lip planar signal unknown
7. 2022 Medium

   Confirmed in human retinal neurons that PRICKLE3 mutation synergizes with mtDNA mutation to cause mitochondrial dysfunction, validating the disease mechanism in patient-derived cells.

   Evidence iPSC-derived RGC-like cells with electrophysiology, ATP and apoptosis assays

   PMID:35947995

   Open questions at the time

   • Mechanism of synergy with m.11778G>A not dissected
   • Single-lab human cell model
8. 2025 High

   Established the biochemical mechanism by which PRICKLE3 stabilizes VANGL at the surface—blocking CK1ε phosphorylation and the CK1ε–RNF43 axis—with isoform specificity over PRICKLE1.

   Evidence miniTurboID/MS interactome, immunoblotting, live imaging, and in vivo PCP/ciliogenesis assays across human cells, Xenopus and zebrafish

   PMID:41455754

   Open questions at the time

   • Structural basis for PRICKLE3 vs PRICKLE1 specificity not defined
   • Whether this activity intersects the mitochondrial role unknown
9. 2025 Medium

   Proposed a cancer-promoting branch in which PRICKLE3 recruits USP9X to stabilize DVL2 and activate canonical WNT signaling, though an independent interactome found no effect of PRICKLE3 on DVL2 levels.

   Evidence Co-IP, knockout/overexpression cell lines, ubiquitination and tumor growth assays (Oncogene); contradicted by miniTurboID/MS at physiological expression (bioRxiv preprint)

   PMID:40973792 PMID:bio_10.1101_2025.03.24.644882

   Open questions at the time

   • Conflicting evidence on whether PRICKLE3 regulates DVL2 stability
   • Overexpression-based effects not reconciled with physiological-level data
10. 2026 Low

    Extended the polarity role to male germ cells, placing PRICKLE3 in a SPEM2–VANGL2–DVL3 complex required for spermiation.

    Evidence Co-IP of SPEM2 with PRICKLE3/VANGL2/DVL3 and Spem2-knockout mouse sperm phenotyping

    PMID:42028965

    Open questions at the time

    • Mechanistic role of PRICKLE3 itself not directly tested
    • Single Co-IP without reciprocal validation of PRICKLE3 function

• It remains unresolved how PRICKLE3 is dually targeted to the plasma membrane PCP machinery and to mitochondria, and whether its canonical WNT/DVL2-stabilizing activity is genuine given conflicting interactome data.
• No mechanism for dual membrane/mitochondrial localization
• DVL2 regulation contradicted between studies
• No structural model of VANGL- or ATP8-binding interfaces