Functional redundancy of frizzled 3 and frizzled 6 in planar cell polarity control of mouse hair follicles

Development. 2018 Oct 8;145(19):dev168468. doi: 10.1242/dev.168468.


The orientation of mouse hair follicles is controlled by the planar cell polarity (PCP) pathway. Mutations in PCP genes result in two categories of hair mis-orientation phenotype: randomly oriented and vertically oriented to the skin surface. Here, we demonstrate that the randomly oriented hair phenotype observed in frizzled 6 (Fzd6) mutants results from a partial loss of the polarity, due to the functional redundancy of another closely related frizzled gene, Fzd3 Double knockout of Fzd3 and Fzd6 globally, or only in the skin, led to vertically oriented hair follicles and a total loss of anterior-posterior polarity. Furthermore, we provide evidence that, contrary to the prevailing model, asymmetrical localization of the Fzd6 protein is not observed in skin epithelial cells. Through transcriptome analyses and in vitro studies, we show collagen triple helix repeat containing 1 (Cthrc1) to be a potential downstream effector of Fzd6, but not of Fzd3. Cthrc1 binds directly to the extracellular domains of Fzd3 and Fzd6 to enhance the Wnt/PCP signaling. These results suggest that Fzd3 and Fzd6 play a redundant role in controlling the polarity of developing skin, but through non-identical mechanisms.

Keywords: Fzd3; Fzd6; Hair follicle; Mouse development; Planar cell polarity; Skin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Cell Polarity*
  • Epithelial Cells / metabolism
  • Extracellular Matrix Proteins / metabolism
  • Feedback, Physiological
  • Frizzled Receptors / metabolism*
  • HEK293 Cells
  • Hair Follicle / cytology*
  • Hair Follicle / metabolism*
  • Humans
  • Integrases / metabolism
  • Mice, Knockout
  • Models, Biological
  • Mosaicism
  • Protein Binding
  • Signal Transduction
  • Skin / cytology


  • Cthrc1 protein, mouse
  • Extracellular Matrix Proteins
  • Frizzled Receptors
  • Fzd3 protein, mouse
  • Fzd6 protein, mouse
  • Cre recombinase
  • Integrases