Influencia de la maquinaria de traducción en el plegamiento de las proteínas :detección de variantes conformacionales del receptor de estrógenos alfa humano en sistemas de traducción in vitro

Orientadora: Dra. Mónica MarínTribunal: Dr. Alfonso Cayota, Dra. Mónica Brauer, Dr. José Souz

The transcriptional activities and cellular localization of the human estrogen receptor alpha are affected by the synonymous Ala87 mutation.

International audience: Until recently, synonymous mutations (which do not change amino acids) have been much neglected. Some evidence suggests that this kind of mutations could affect mRNA secondary structure or stability, translation kinetics and protein structure. To explore deeper the role of synonymous mutations, we studied their consequence on the functional activity of the estrogen receptor alpha (ERα). The ERα is a ligand-inducible transcription factor that orchestrates pleiotropic cellular effects, at both genomic and non-genomic levels in response to estrogens. In this work we analyzed in transient transfection experiments, the activity of ERα carrying the synonymous mutation Ala87, a polymorphism involving about 5-10% of the population. In comparison to the wild type receptor, our results show that ERαA87 mutation reduces the transactivation efficiency of ERα on an ERE reporter gene while its expression level remains similar. This mutation enhances 4-OHT-induced transactivation of ERα on an AP1 reporter gene. Finally, the mutation affects the subcellular localization of ERα in a cell type specific manner. It enhances the cytoplasmic location of ERα without significant changes in non-genomic effects of E2. The functional alteration of the ERαA87 determined in this work highlights the relevance of synonymous mutations for biomedical and pharmacological points of view

The crystal structure of the MAP kinase LmaMPK10 from leishmania major reveals parasite-specific features and regulatory mechanisms

Mitogen-activated protein kinases (MAPKs) are involved in environmental signal sensing. They are thus expected to play key roles in the biology of Trypanosomatid parasites, which display complex life cycles and use extracellular cues to modulate cell differentiation. Despite their relevance, structural data of Trypanosomatid MAPKs is lacking. We have now determined the crystal structure of Leishmania major LmaMPK10, a stage-specifically activated MAPK, both alone and in complex with SB203580. LmaMPK10 was observed to be more similar to p38 than to other human MAPKs. However, significant differences could be identified in the catalytic pocket, as well as in potentially regulatory sites in the N-terminal lobe. The modified pocket architecture in LmaMPK10 precludes DFG-in/DFG-out regulatory flipping as observed in mammalian MAPKs. LmaMPK10-nucleotide association was also studied, revealing a potential C-terminal autoinhibitory mechanism. Overall, these data should speed the discovery of molecules interfering with LmaMPK10 functions, with relevance for antileishmanial drug development strategies.Fil: Horjales, Sofía. Instituto Pasteur de Montevideo; UruguayFil: Schmidt Arras, Dirk. Instituto Pasteur; FranciaFil: Rodriguez Limardo, Ramiro Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Leclercq, Olivier. Instituto Pasteur; FranciaFil: Obal, Gonzalo. Instituto Pasteur de Montevideo; UruguayFil: Prina, Eric. Instituto Pasteur; FranciaFil: Turjanski, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Späth, Gerald F.. Instituto Pasteur; FranciaFil: Buschiazzo, Alejandro. Instituto Pasteur de Montevideo; Uruguay. Instituto Pasteur; Franci