Nouveaux modes de régulation des voies MAP kinase eucaryotes par phosphorylation

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

La confrontation de conventions professionnelles au coeur de la socialisation d’enseignant·e·s formé·e·s à l’étranger travaillant dans l’école montréalaise

Cet article a pour but de présenter les résultats d’une recherche portant sur la socialisation professionnelle d’enseignant·e·s formé·e·s à l’étranger s’intégrant dans les écoles montréalaises. Une série d’entretiens collectifs a été proposée à certain·e·s d’entre elles·eux et à des pairs mentors afin de co-analyser des évènements concrets ayant marqué leur intégration et de débattre de leurs significations. Les résultats mettent en lumière deux dimensions majeures de leur socialisation : le rapport aux élèves et la régulation des conduites dans les classes, et la participation à la communauté de pairs et la définition de la compétence professionnelle.This article aims to present the results of research on professional socialization of internationally educated teachers integrating into Montreal schools. A series of group interviews were offered to some of them and to peer mentors to co-analyze concrete events that marked their integration and discuss their meanings. The results highlight two major dimensions of their socialization: the relationship with students and the regulation of classroom behavior, as well as the participation in the peer community and the meaning of professional competence.Este artículo tiene el objetivo de presentar los resultados de una investigación sobre la socialización profesional de maestros formados en el extranjero y que se integran en las escuelas de Montreal. Propusimos una serie de entrevistas colectivas en las que participaron maestros con este perfil y sus mentores asociados en la escuela, con la finalidad de co-analizar algunos eventos concretos que hubieran marcado su integración y de debatir sobre sus significados. Los resultados ponen de manifiesto dos dimensiones principales de su socialización: 1) la relación con los alumnos y la regulación de los comportamientos en clase; 2) la participación a la comunidad de pares y la definición de la competencia profesional

Tissue-specific GATA factors are transcriptional effectors of the small GTPase RhoA

Rho-like GTPases play a pivotal role in the orchestration of changes in the actin cytoskeleton in response to receptor stimulation, and have been implicated in transcriptional activation, cell growth regulation, and oncogenic transformation. Recently, a role for RhoA in the regulation of cardiac contractility and hypertrophic cardiomyocyte growth has been suggested but the mechanisms underlying RhoA function in the heart remain undefined. We now report that transcription factor GATA-4, a key regulator of cardiac genes, is a nuclear mediator of RhoA signaling and is involved in the control of sarcomere assembly in cardiomyocytes. Both RhoA and GATA-4 are essential for sarcomeric reorganization in response to hypertrophic growth stimuli and overexpression of either protein is sufficient to induce sarcomeric reorganization. Consistent with convergence of RhoA and GATA signaling, RhoA potentiates the transcriptional activity of GATA-4 via a p38 MAPK-dependent pathway that phosphorylates GATA-4 activation domains and GATA binding sites mediate RhoA activation of target cardiac promoters. Moreover, a dominant-negative GATA-4 protein abolishes RhoA-induced sarcomere reorganization. The identification of transcription factor GATA-4 as a RhoA mediator in sarcomere reorganization and cardiac gene regulation provides a link between RhoA effects on transcription and cell remodeling

Phosphorylation of the MAPKKK Regulator Ste50p in Saccharomyces cerevisiae: a Casein Kinase I Phosphorylation Site Is Required for Proper Mating Function

The Ste50 protein of Saccharomyces cerevisiae is a regulator of the Ste11p protein kinase. Ste11p is a member of the MAP3K (or MEKK) family, which is conserved from yeast to mammals. Ste50p is involved in all the signaling pathways that require Ste11p function, yet little is known about the regulation of Ste50p itself. Here, we show that Ste50p is phosphorylated on multiple serine/threonine residues in vivo. Threonine 42 (T42) is phosphorylated both in vivo and in vitro, and the protein kinase responsible has been identified as casein kinase I. Replacement of T42 with alanine (T42A) compromises Ste50p function. This mutation abolishes the ability of overexpressed Ste50p to suppress either the mating defect of a ste20 ste50 deletion mutant or the mating defect of a strain with a Ste11p deleted from its sterile-alpha motif domain. Replacement of T42 with a phosphorylation-mimetic aspartic acid residue (T42D) permits wild-type function in all assays of Ste50p function. These results suggest that phosphorylation of T42 of Ste50p is required for proper signaling in the mating response. However, this phosphorylation does not seem to have a detectable role in modulating the high-osmolarity glycerol synthesis pathway