Abstract
The non-canonical Wnt/cyclic GMP/Ca(2+)/NF-AT pathway operates via Frizzled-2, a member of the superfamily of G protein-coupled receptors. In scanning for signaling events downstream of the Frizzled-2/G alpha t2/PDE6 triad activated in response to Wnt5a, we observed a strong activation of the mitogen-activated protein kinase p38 in mouse F9 teratocarcinoma embryonal cells. The activation of p38 is essential for NF-AT transcriptional activation mediated via Frizzled2. Wnt5a-stimulated p38 activation was rapid, sensitive to pertussis toxin, to siRNA against either G alpha t2 or p38 alpha, and to the p38 inhibitor SB203580. Real-time analysis of intracellular cyclic GMP using the Cygnet2 biosensor revealed p38 to act at the level of cyclic GMP, upstream of the mobilization of intracellular Ca(2+). Fluorescence resonance energy transfer (FRET) imaging reveals the changes in cyclic GMP in response to Wnt5a predominate about the cell membrane, and likewise sensitive to either siRNA targeting p38 or to treatment with SB203580. Dishevelled is not required for Wnt5a activation of p38; siRNAs targeting Dishevelleds and expression of the Dishevelled antagonist Dapper-1 do not suppress the p38 response to Wnt5a stimulation. These novel results are the first to detail a Dishevelled-independent Wnt response, demonstrating a critical role of the mitogen-activated protein kinase p38 in regulating the Wnt non-canonical pathway.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Adaptor Proteins, Signal Transducing / antagonists & inhibitors
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Adaptor Proteins, Signal Transducing / metabolism
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Animals
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Calcium / metabolism
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Calcium Signaling / drug effects
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Calcium Signaling / physiology*
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Cell Line, Tumor
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Cyclic GMP / metabolism*
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Cyclic Nucleotide Phosphodiesterases, Type 6
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Dishevelled Proteins
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Enzyme Activation / drug effects
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Enzyme Activation / physiology
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Enzyme Inhibitors / pharmacology
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Frizzled Receptors / metabolism
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Imidazoles / pharmacology
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Intracellular Signaling Peptides and Proteins / metabolism
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Mice
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NFATC Transcription Factors / metabolism
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Pertussis Toxin / pharmacology
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Phosphoproteins / antagonists & inhibitors
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Phosphoproteins / metabolism
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Phosphoric Diester Hydrolases / metabolism
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Pyridines / pharmacology
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RGS Proteins / metabolism
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RNA-Binding Proteins
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Receptors, G-Protein-Coupled / metabolism
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Wnt Proteins / metabolism*
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Wnt-5a Protein
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p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
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p38 Mitogen-Activated Protein Kinases / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Dishevelled Proteins
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Enzyme Inhibitors
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Frizzled Receptors
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Fzd2 protein, mouse
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Imidazoles
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Intracellular Signaling Peptides and Proteins
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NFATC Transcription Factors
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Phosphoproteins
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Pyridines
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RGS Proteins
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RNA-Binding Proteins
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Receptors, G-Protein-Coupled
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Wnt Proteins
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Wnt-5a Protein
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Wnt5a protein, mouse
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frodo protein, mouse
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regulator of G-protein signalling 19
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Pertussis Toxin
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p38 Mitogen-Activated Protein Kinases
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Phosphoric Diester Hydrolases
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Cyclic Nucleotide Phosphodiesterases, Type 6
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Pde6b protein, mouse
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Cyclic GMP
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SB 203580
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Calcium