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Reference : UMR9198-ANGDEL-001
Workplace : GIF SUR YVETTE
Date of publication : Monday, July 27, 2020
Scientific Responsible name : Angélique DELERIS
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
In plants and many organisms, DNA methylation is a hallmark of transposable elements (TE) which negatively controls TE expression. On the other hand, histone H3 lysine 27 trimethylation (H3K27me3), targeted by the highly conserved Polycomb Group (PcG) proteins, is a hallmark of transcriptional repression associated with protein-coding genes. Nevertheless, there is a growing body of evidence for interplay between these pathways. In particular, many TE sequences, upon their loss of DNA methylation and/or in certain cell-types, or even sometimes in addition to DNA methylation, display H3K27me3 marks. This raises fundamental questions with regards to the differences and commonalities between PcG- and DNA methylation-mediated silencing. We propose to address them in Arabidopsis thaliana_a powerful model to study the epigenetic regulation of TEs.
We want to address how DNA methylation and Polycomb mediate silencing at TEs, and study their repression potential, in particular during biotic stress-induced TE activation. To reach this objective, we will address the crosstalk between transcription factors (TF) and TE silencing by DNA methylation and PcG, using first a TE model locus for which we have a solid and relevant framework. We will identify and characterize the transcription factors (TF) that control this TE expression, as a starting point to next monitor the effect of PcG and DNA methylation on the binding of TFs and PolII, and on subsequent transcription (AIM1). Furthermore, we propose to study the significance of this crosstalk at the genome-wide level by studying the occurrence of TE neoinsertions in the progeny of bacteria-elicited plants as a readout of transpositions that occurred in the cell types critical for heritable changes and by using TE-capture as a sensitive method for their detection (AIM2).
This work will be carried on at I2BC (Gif/Yvette)in the department of Genome Biology, in the team "Epigenetic regulation of transposable elements".
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