G Protein-regulated Inducer of Neurite Outgrowth (GRIN) Modulates Sprouty Protein Repression of Mitogen-activated Protein Kinase (MAPK) Activation by Growth Factor Stimulation

Gαo/i interacts directly with GRIN (G protein-regulated inducer of neurite outgrowth). Using the yeast two-hybrid system, we identified Sprouty2 as an interacting partner of GRIN. Gαo and Sprouty2 bind to overlapping regions of GRIN, thus competing for GRIN binding. Imaging experiments demonstrated that Gαo expression promoted GRIN translocation to the plasma membrane, whereas Sprouty2 expression failed to do so. Given the role of Sprouty2 in the regulation of growth factor-mediated MAPK activation, we examined the contribution of the GRIN-Sprouty2 interaction to CB1 cannabinoid receptor regulation of FGF receptor signaling. In Neuro-2A cells, a system that expresses all of the components endogenously, modulation of GRIN levels led to regulation of MAPK activation. Overexpression of GRIN potentiated FGF activation of MAPK and decreased tyrosine phosphorylation of Sprouty2. Pretreatment with Go/i-coupled CB1 receptor agonist attenuated subsequent FGF activation of MAPK. Decreased expression of GRIN both diminished FGF activation of MAPK and blocked CB1R attenuation of MAPK activation. These observations indicate that Gαo interacts with GRIN and outcompetes GRIN from bound Sprouty. Free Sprouty then in turn inhibits growth factor signaling. Thus, here we present a novel mechanism of how Go/i-coupled receptors can inhibit growth factor signaling to MAPK

Martínez Estrada y Scalabrini Ortiz en la (Re)construcción de los Discursos de Identidad Nacional

La produccion literaria aumenta en los momentos cruciales y criticos del pais ya que los escritores, para lograr una autoafirmacion nacional, piden cambios, indagan y hacen una revalorizacion del ser nacional a traves de sus obras. De esta manera, los planteamientos de los escripores constituyen ideas fundamentales para cuestionar, interpretar y transformar los discursos de identidad nacional de su epoca. Ambos escritores, tanto Ezequiel Martinez Estrada como Raul Scalabrini Ortiz, definen "lo que no debemos ser" en un caso y "lo que somos" en el otro, participando asi activamente en la (re)construccion de los discursos de identidad nacional