Frizzled Proteins Are Colonic Epithelial Receptors for C. Difficile Toxin B

Nature. 2016 Oct 20;538(7625):350-355. doi: 10.1038/nature19799. Epub 2016 Sep 28.

Abstract

Clostridium difficile toxin B (TcdB) is a critical virulence factor that causes diseases associated with C. difficile infection. Here we carried out CRISPR-Cas9-mediated genome-wide screens and identified the members of the Wnt receptor frizzled family (FZDs) as TcdB receptors. TcdB binds to the conserved Wnt-binding site known as the cysteine-rich domain (CRD), with the highest affinity towards FZD1, 2 and 7. TcdB competes with Wnt for binding to FZDs, and its binding blocks Wnt signalling. FZD1/2/7 triple-knockout cells are highly resistant to TcdB, and recombinant FZD2-CRD prevented TcdB binding to the colonic epithelium. Colonic organoids cultured from FZD7-knockout mice, combined with knockdown of FZD1 and 2, showed increased resistance to TcdB. The colonic epithelium in FZD7-knockout mice was less susceptible to TcdB-induced tissue damage in vivo. These findings establish FZDs as physiologically relevant receptors for TcdB in the colonic epithelium.

MeSH terms

  • Animals
  • Antigens / metabolism
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Bacterial Toxins / chemistry
  • Bacterial Toxins / metabolism*
  • Binding Sites
  • CHO Cells
  • CRISPR-Cas Systems
  • Cell Line
  • Clostridium difficile / pathogenicity
  • Colon / metabolism*
  • Cricetulus
  • Epithelium / metabolism*
  • Female
  • Frizzled Receptors / chemistry
  • Frizzled Receptors / deficiency
  • Frizzled Receptors / genetics
  • Frizzled Receptors / metabolism*
  • Gene Knockout Techniques
  • Humans
  • Male
  • Mice
  • Mice, Knockout
  • Oligopeptides / chemistry
  • Oligopeptides / metabolism
  • Organoids / metabolism
  • Protein Domains
  • Proteoglycans / metabolism
  • Virulence Factors / metabolism
  • Wnt Proteins / metabolism

Substances

  • Antigens
  • Bacterial Proteins
  • Bacterial Toxins
  • Frizzled Receptors
  • Oligopeptides
  • Proteoglycans
  • Virulence Factors
  • Wnt Proteins
  • chondroitin sulfate proteoglycan 4
  • toxB protein, Clostridium difficile