Expression profiles of the Ga subunits during Xenopus tropicalis embryonic development Jaime Fuentealba a, 1 , Gabriela Toro-Tapia a, 1 , Marion Rodriguez a , Cecilia Arriagada a , Alejandro Maureira a , Andrea Beyer a , Soraya Villaseca a , Juan I. Leal a , Maria V. Hinrichs a , Juan Olate a , Teresa Caprile b , Marcela Torrej  on a, * a Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biol ogicas, Universidad de Concepci on, Casilla 160-C, Concepci on, Chile b Departamento de Biología Celular, Facultad de Ciencias Biol ogicas, Universidad de Concepci on, Casilla 160-C, Concepci on, Chile article info Article history: Received 25 April 2016 Received in revised form 31 July 2016 Accepted 4 September 2016 Available online 7 September 2016 Keywords: Xenopus G protein Embryogenesis Gai Gaq Ga13 Gas Neural crest abstract Heterotrimeric G protein signaling plays major roles during different cellular events. However, there is a limited understanding of the molecular mechanisms underlying G protein control during embryogenesis. G proteins are highly conserved and can be grouped into four subfamilies according to sequence ho- mology and function. To further studies on G protein function during embryogenesis, the present analysis identified four Ga subunits representative of the different subfamilies and determined their spatiotemporal expression patterns during Xenopus tropicalis embryogenesis. Each of the Ga subunit transcripts was maternally and zygotically expressed, and, as development progressed, dynamic expression patterns were observed. In the early developmental stages, the Ga subunits were expressed in the animal hemisphere and dorsal marginal zone. While expression was observed at the somite boundaries, in vascular structures, in the eye, and in the otic vesicle during the later stages, expression was mainly found in neural tissues, such as the neural tube and, especially, in the cephalic vesicles, neural crest region, and neural crest-derived structures. Together, these results support the pleiotropism and complexity of G protein subfamily functions in different cellular events. The present study consti- tutes the most comprehensive description to date of the spatiotemporal expression patterns of Ga subunits during vertebrate development. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Heterotrimeric G proteins, which are composed by a, b, and g subunits, are activated through G protein coupled receptors (GPCRs). During intracellular signaling, the b and g subunits are bound together and form the Gbg complex. This complex, as well as Ga, modulates the activity of different effector proteins. Ga has intrinsic guanosine triphosphate (GTP)-hydrolyzing activity, pre- senting an activated state when bound to GTP and an inactivated state when bound to guanosine diphosphate (GDP). During the canonical cycle of the heterotrimeric G protein, activation begins when a ligand binds to its corresponding GPCR, which acts as a guanine nucleotide exchange factor (GEF) to induce the exchange of GDP for GTP in the Ga subunit. Subsequently, the Ga subunit dis- sociates from the Gbg dimer, and both Ga-GTP and Gbg continue signaling through different effectors. This signaling is terminated when GTP is hydrolyzed to GDP through intrinsic GTPase activity of the Ga subunit (Gilman, 1987). In mammals, 20 heterotrimeric G proteins have been described. Each G protein includes a unique Ga subunit combined with one of 5Gb subunits and one of 12 Gg subunits (Malbon, 2005). In other genetic models, such as Xenopus and Dictyostelum discoideum, at least ten Ga subunits have been reported. Furthermore, hetero- trimeric G proteins are classified into four families according to similarities in functions and protein structures of the Ga subunits. These families are Gas, Gai/o, Gaq/11, and Ga12/13, all of which are involved in different processes during embryogenesis (Wilkie et al., 1992; Malbon, 2005). In addition to GPCRs, many other G protein regulators have been described. One of these proteins is the regulator of G protein signaling (RGS), which possesses GTPase activating protein (GAP) * Corresponding author. E-mail address: matorrejon@udec.cl (M. Torrej on). 1 These authors contributed equally to this work. Contents lists available at ScienceDirect Gene Expression Patterns journal homepage: http://www.elsevier.com/locate/gep http://dx.doi.org/10.1016/j.gep.2016.09.001 1567-133X/© 2016 Elsevier B.V. All rights reserved. Gene Expression Patterns 22 (2016) 15e25