title: Disheveled regulates precoupling of heterotrimeric G proteins to Frizzled 6.
abstract: Frizzleds (FZDs) are classified as G-protein-coupling receptors, but how signals are initiated and specified through heterotrimeric G proteins is unknown. FZD6 regulates convergent extension movements, and its C-terminal Arg511Cys mutation causes nail dysplasia in humans. We investigated the functional relationship between FZD6, Disheveled (DVL), and heterotrimeric G proteins. Live cell imaging combined with fluorescence recovery after photobleaching (FRAP) revealed that inactive human FZD6 precouples to Gαi1 and Gαq but not to GαoA,Gαs, and Gα12 proteins. G-protein coupling is measured as a 10-20% reduction in the mobile fraction of fluorescently tagged G proteins on chemical receptor surface cross-linking. The FZD6 Arg511Cys mutation is incapable of G-protein precoupling, even though it still binds DVL. Using both FRAP and Förster resonance energy transfer (FRET) technology, we showed that the FZD6-Gαi1 and FZD-Gαq complexes dissociate on WNT-5A stimulation. Most important, G-protein precoupling of FZD6 and WNT-5A-induced signaling to extracellular signal-regulated kinase1/2 were impaired by DVL knockdown or overexpression, arguing for a strict dependence of FZD6-G-protein coupling on DVL levels and identifying DVL as a master regulator of FZD/G-protein signaling. In summary, we propose a mechanistic connection between DVL and G proteins integrating WNT, FZD, G-protein, and DVL function.
authors: 2Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz väg 2, S-171 77 Stockholm, Sweden. gunnar.schulte@ki.se.
authors: Michaela B C
authors: MB
authors: Kilander
authors: Julian
authors: J
authors: Petersen
authors: Kjetil Wessel
authors: KW
authors: Andressen
authors: Ranjani Sri
authors: RS
authors: Ganji
authors: Finn Olav
authors: FO
authors: Levy
authors: Jens
authors: J
authors: Schuster
authors: Niklas
authors: N
authors: Dahl
authors: Vitezslav
authors: V
authors: Bryja
authors: Gunnar
authors: G
authors: Schulte
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D000072261:Dishevelled Proteins; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D031541:Fluorescence Resonance Energy Transfer; D051157:Frizzled Receptors / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism; D000071818:Wnt-5a Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000072261:Dishevelled Proteins; C484687:FZD6 protein, human; D051157:Frizzled Receptors; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; C085389:WNT5A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D049452:Green Fluorescent Proteins; D048049:Extracellular Signal-Regulated MAP Kinases; D020962:Heterotrimeric GTP-Binding Proteins
keywords: GNAI1; GNAQ; GPCR; WNT-5A