Régulation épigénétique des éléments transposables chez Arabidopsis
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Institut de Biologie Intégrative de la Cellule (I2BC), CNRS UMR 9198, CEA, Université Paris-Saclay
1, avenue de la terrasse
91198 Gif-sur-Yvette cedex
FRANCE
Intérêt scientifique
Transposable Elements (TE) are repeated sequences that can potentially move and multiply in the genome. They often have been found to be activated in response to stress such as that induced by microbial infection. Transposition can be deleterious and is repressed via several layers of regulation; on the other hand, TE mobilization has been recognized as a driving force of evolution and adaptation in various organisms, in particular by providing nearby genes with genetic or epigenetic regulatory modules that can impact transcriptional programs. Therefore, the study of TE regulation is essential to understand both the conditions for their transposition and their influence on nearby genes, thus their potential for conferring adaptation. My team studies, in the model plant Arabidopsis thaliana, the molecular determinants TE activation -in particular during biotic stress- as well as the epigenetic mechanisms (RNAi, DNA methylation, Polycomb-mediated Histone 3 Lysine 27 trimethylation) that negatively control TE transcription; we also want to understand the crosstalk between these activating and silencing pathways and its output as for TE transcription and transposition during plant-pathogen interactions. We are tackling a number of fundamental issues: 1) What are the transcription factors that associate with a given TE and their interactions with epigenetic marks, in particular during stress response? 2) What is the biological role of Polycomb at TEs and its repression potential compared to DNA methylation? What determines Polycomb complexes recruitment at TEs and what could favour it, sometimes, over DNA methylation? 3) What is the balance between TE activation and silencing during various biotic stresses? How is transposition regulated in this context? What is the impact on plant-pathogen interactions? For this purpose, we implement genetic and molecular biology approaches associated with emerging epigenomic as well as DNA/ RNA centered methodologies to analyze chromatin and transposition.
Transposable Elements (TE) are repeated sequences that can potentially move and multiply in the genome. They often have been found to be activated in response to stress such as that induced by microbial infection. Transposition can be deleterious and is repressed via several layers of regulation; on the other hand, TE mobilization has been recognized as a driving force of evolution and adaptation in various organisms, in particular by providing nearby genes with genetic or epigenetic regulatory modules that can impact transcriptional programs. Therefore, the study of TE regulation is essential to understand both the conditions for their transposition and their influence on nearby genes, thus their potential for conferring adaptation. My team studies, in the model plant Arabidopsis thaliana, the molecular determinants TE activation -in particular during biotic stress- as well as the epigenetic mechanisms (RNAi, DNA methylation, Polycomb-mediated Histone 3 Lysine 27 trimethylation) that negatively control TE transcription; we also want to understand the crosstalk between these activating and silencing pathways and its output as for TE transcription and transposition during plant-pathogen interactions. We are tackling a number of fundamental issues: 1) What are the transcription factors that associate with a given TE and their interactions with epigenetic marks, in particular during stress response? 2) What is the biological role of Polycomb at TEs and its repression potential compared to DNA methylation? What determines Polycomb complexes recruitment at TEs and what could favour it, sometimes, over DNA methylation? 3) What is the balance between TE activation and silencing during various biotic stresses? How is transposition regulated in this context? What is the impact on plant-pathogen interactions? For this purpose, we implement genetic and molecular biology approaches associated with emerging epigenomic as well as DNA/ RNA centered methodologies to analyze chromatin and transposition.
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