title: Dishevelled-2 docks and activates Src in a Wnt-dependent manner.
abstract: Wnt3a activates the ;canonical' signaling pathway, stimulating the nuclear accumulation of beta-catenin and activation of Lef/Tcf-sensitive transcription of developmentally important genes. Using totipotent mouse F9 teratocarcinoma cells expressing frizzled-1 (Fz1), we investigated roles of tyrosine kinase activity in Wnt/beta-catenin signaling. Treatment with either genistein or Src family kinase inhibitor PP2 attenuates Wnt3a-stimulated Lef/Tcf transcription activation and primitive endoderm formation. siRNA-induced knockdown of Src likewise attenuates Lef/Tcf transcription and primitive endoderm formation in response to Wnt3a, implicating Src as a positive regulator of Wnt/beta-catenin signaling. We discovered that Src binds dishevelled-2 (Dvl2), a key phosphoprotein in Wnt signaling, at two positions: an SH3-binding domain and a C-terminal domain. The Y18F mutant of Dvl2 attenuates the Wnt3a-stimulated Lef/Tcf-sensitive transcriptional response. Wnt3a stimulates Src docking to Dvl2 and activation of this tyrosine kinase. Activated Src, in turn, enhances Wnt activation of the canonical pathway. We show that Dvl2 and beta-catenin are crucially important substrates for tyrosine phosphorylation in the canonical Wnt/beta-catenin pathway.
authors.affiliation: Department of Pharmacology, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, NY 11794-8651, USA. noriko@pharm.stonybrook.edu
authors.forename: Noriko
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Craig C
authors.initials: CC
authors.lastname: Malbon
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000072261:Dishevelled Proteins; D004789:Enzyme Activation; D051379:Mice; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D051822:T Cell Transcription Factor 1 / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000072261:Dishevelled Proteins; C000606582:Dvl2 protein, mouse; D010750:Phosphoproteins; D051822:T Cell Transcription Factor 1; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D051176:beta Catenin; D019061:src-Family Kinases