Protein kinase C is differentially stimulated by Wnt and Frizzled homologs in a G-protein-dependent manner

Curr Biol. 1999 Jul 1;9(13):695-8. doi: 10.1016/s0960-9822(99)80310-8.


In studies of developmental signaling pathways stimulated by the Wnt proteins and their receptors, Xenopus Wnt-5A (Xwnt-5A) and a prospective Wnt receptor, rat Frizzled 2 (Rfz2), have been shown to stimulate inositol signaling and Ca2+ fluxes in zebrafish [1] [2] [3]. As protein kinase C (PKC) isoforms can respond to Ca2+ signals [4], we asked whether expression of different Wnt and Frizzled homologs modulates PKC. Expression of Rfz2 and Xwnt-5A resulted in translocation of PKC to the plasma membrane, whereas expression of rat Frizzled 1 (Rfz1), which activates a Wnt pathway using beta-catenin but not Ca2+ fluxes [5], did not. Rfz2 and Xwnt-5A were also able to stimulate PKC activity in an in vitro kinase assay. Agents that inhibit Rfz2-induced signaling through G-protein subunits blocked Rfz2-induced translocation of PKC. To determine if other Frizzled homologs differentially stimulate PKC, we tested mouse Frizzled (Mfz) homologs for their ability to induce PKC translocation relative to their ability to induce the expression of two target genes of beta-catenin, siamois and Xnr3. Mfz7 and Mfz8 stimulated siamois and Xnr3 expression but not PKC activation, whereas Mfz3, Mfz4 and Mfz6 reciprocally stimulated PKC activation but not expression of siamois or Xnr3. These results demonstrate that some but not all Wnt and Frizzled signals modulate PKC localization and stimulate PKC activity via a G-protein-dependent mechanism. In agreement with other studies [1] [2] [3]. [6] [7] these data support the existence of multiple Wnt and Frizzled signaling pathways in vertebrates.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Cytoskeletal Proteins / metabolism
  • Eye Proteins / metabolism
  • GTP-Binding Proteins / metabolism
  • Glycoproteins / metabolism
  • Homeodomain Proteins / metabolism
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins*
  • Mice
  • Microscopy, Confocal
  • Polymerase Chain Reaction
  • Protein Kinase C / metabolism*
  • Proteins / metabolism
  • Rats
  • Receptors, Transforming Growth Factor beta / metabolism
  • Trans-Activators*
  • Transforming Growth Factor beta*
  • Wnt Proteins
  • Wnt-5a Protein
  • Xenopus
  • Xenopus Proteins*
  • beta Catenin


  • CTNNB1 protein, Xenopus
  • CTNNB1 protein, mouse
  • Ctnnb1 protein, rat
  • Cytoskeletal Proteins
  • Eye Proteins
  • Glycoproteins
  • Homeodomain Proteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Proteins
  • Receptors, Transforming Growth Factor beta
  • SIA1 protein, Xenopus
  • Sfrp2 protein, mouse
  • Trans-Activators
  • Transforming Growth Factor beta
  • WD repeat containing planar cell polarity effector
  • Wnt Proteins
  • Wnt-5a Protein
  • Wnt5a protein, Xenopus
  • Xenopus Proteins
  • beta Catenin
  • nodal3.1 protein, Xenopus
  • Protein Kinase C
  • GTP-Binding Proteins