title: Rho GTPase activity modulates Wnt3a/beta-catenin signaling.
abstract: Wnt proteins constitute a family of secreted signaling molecules that regulate highly conserved pathways essential for development and, when aberrantly activated, drive oncogenesis in a number of human cancers. A key feature of the most widely studied Wnt signaling cascade is the stabilization of cytosolic beta-catenin, resulting in beta-catenin nuclear translocation and transcriptional activation of multiple target genes. In addition to this canonical, beta-catenin-dependent pathway, Wnt3A has also been shown to stimulate RhoA GTPase. While the importance of activated Rho to non-canonical Wnt signaling is well appreciated, the potential contribution of Wnt3A-stimulated RhoA to canonical beta-catenin-dependent transcription has not been examined and is the focus of this study. We find that activated Rho is required for Wnt3A-stimulated osteoblastic differentiation in C3H10T1/2 mesenchymal stem cells, a biological phenomenon mediated by stabilized beta-catenin. Using expression microarrays and real-time RT-PCR analysis, we show that Wnt3A-stimulated transcription of a subset of target genes is Rho-dependent, indicating that full induction of these Wnt targets requires both beta-catenin and Rho activation. Significantly, neither beta-catenin stabilization nor nuclear translocation stimulated by Wnt3A is affected by inhibition or activation of RhoA. These findings identify Rho activation as a critical element of the canonical Wnt3A-stimulated, beta-catenin-dependent transcriptional program.
authors.affiliation: Duke University Medical Center, Department of Pathology, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Rossol-Allison
authors.forename: Laura N
authors.initials: LN
authors.lastname: Stemmle
authors.forename: Katherine I
authors.initials: KI
authors.lastname: Swenson-Fields
authors.forename: Patrick
authors.initials: P
authors.lastname: Kelly
authors.forename: Patrick E
authors.initials: PE
authors.lastname: Fields
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: McCall
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Casey
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Fields
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D015398:Signal Transduction; D014158:Transcription, Genetic; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D051176:beta Catenin / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: C555510:WNT3A protein, human; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D051176:beta Catenin; D020742:rhoA GTP-Binding Protein