The polarity protein Inturned links NPHP4 to Daam1 to control the subapical actin network in multiciliated cells

J Cell Biol. 2015 Dec 7;211(5):963-73. doi: 10.1083/jcb.201502043.


Motile cilia polarization requires intracellular anchorage to the cytoskeleton; however, the molecular machinery that supports this process remains elusive. We report that Inturned plays a central role in coordinating the interaction between cilia-associated proteins and actin-nucleation factors. We observed that knockdown of nphp4 in multiciliated cells of the Xenopus laevis epidermis compromised ciliogenesis and directional fluid flow. Depletion of nphp4 disrupted the subapical actin layer. Comparison to the structural defects caused by inturned depletion revealed striking similarities. Furthermore, coimmunoprecipitation assays demonstrated that the two proteins interact with each other and that Inturned mediates the formation of ternary protein complexes between NPHP4 and DAAM1. Knockdown of daam1, but not formin-2, resulted in similar disruption of the subapical actin web, whereas nphp4 depletion prevented the association of Inturned with the basal bodies. Thus, Inturned appears to function as an adaptor protein that couples cilia-associated molecules to actin-modifying proteins to rearrange the local actin cytoskeleton.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / metabolism*
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Basal Bodies / metabolism
  • Cilia / metabolism*
  • Drosophila melanogaster
  • Epidermis / metabolism
  • Gene Knockdown Techniques
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Immunoprecipitation
  • Membrane Proteins / metabolism
  • Microfilament Proteins / metabolism*
  • Molecular Sequence Data
  • Oligonucleotides / chemistry
  • Protein Binding
  • Protein Structure, Tertiary
  • Proteins / metabolism*
  • Xenopus Proteins / metabolism*
  • Xenopus laevis / metabolism
  • rho GTP-Binding Proteins


  • Actins
  • Adaptor Proteins, Signal Transducing
  • DAAM1 protein, human
  • Daam1 protein, Xenopus
  • INTU protein, Xenopus
  • Membrane Proteins
  • Microfilament Proteins
  • NPHP4 protein, human
  • Oligonucleotides
  • Proteins
  • Xenopus Proteins
  • Green Fluorescent Proteins
  • rho GTP-Binding Proteins

Associated data

  • GENBANK/BC130611
  • RefSeq/NM_014992
  • RefSeq/NM_015102
  • RefSeq/NM_020148
  • RefSeq/NM_057618