title: Galphaq negatively regulates the Wnt-beta-catenin pathway and dorsal embryonic Xenopus laevis development.
abstract: The non-canonical Wnt/Ca2+ signaling pathway has been implicated in the regulation of axis formation and gastrulation movements during early Xenopus laevis embryo development, by antagonizing the canonical Wnt/beta-catenin dorsalizing pathway and specifying ventral cell fate. However, the molecular mechanisms involved in this antagonist crosstalk are not known. Since Galphaq is the main regulator of Ca2+ signaling in vertebrates and from this perspective probably involved in the events elicited by the non-canonical Wnt/Ca2+ pathway, we decided to study the effect of wild-type Xenopus Gq (xGalphaq) in dorso-ventral axis embryo patterning. Overexpression of xGalphaq or its endogenous activation at the dorsal animal region of Xenopus embryo both induced a strong ventralized phenotype and inhibited the expression of dorsal-specific mesoderm markers goosecoid and chordin. Dorsal expression of an xGalphaq dominant-negative mutant reverted the xGalphaq-induced ventralized phenotype. Finally, we observed that the Wnt8-induced secondary axis formation is reverted by endogenous xGalphaq activation, indicating that it is negatively regulating the Wnt/beta-catenin pathway.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Casilla 160-C, Universidad de Concepción, Concepción, Chile.
authors.forename: Ximena
authors.initials: X
authors.lastname: Soto
authors.forename: Roberto
authors.initials: R
authors.lastname: Mayor
authors.forename: Marcela
authors.initials: M
authors.lastname: Torrejón
authors.forename: Martín
authors.initials: M
authors.lastname: Montecino
authors.forename: María Victoria
authors.initials: MV
authors.lastname: Hinrichs
authors.forename: Juan
authors.initials: J
authors.lastname: Olate
mesh_terms: D000818:Animals; D019521:Body Patterning; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D054262:Gastrulation; D018507:Gene Expression Regulation, Developmental; D051153:Wnt Proteins / Q000037:antagonists & inhibitors*; D014982:Xenopus laevis / Q000196:embryology / Q000378:metabolism*; D051176:beta Catenin / Q000037:antagonists & inhibitors*
chemical_list: D051153:Wnt Proteins; D051176:beta Catenin; D043802:GTP-Binding Protein alpha Subunits, Gq-G11