In eukaryotes, the transcription cycle is composed of several steps, each of them being strictly controlled by several factors. These factors act mainly through modulation of RNA Polymerase II catalytic activity and chromatin remodeling. In addition, in mammals and in yeast, some MAP kinases have been shown to be recruited on chromatin in response to external cues to control transcription. For many years, pre-initiation and initiation were considered as the main controlled steps. However, RNA Polymerase II undergoes a promoter-proximal pausing which is also crucial to regulate transcriptional activity. During my PhD, I addressed the functional relationships between the chromatin factor Corto, the MAPK ERK and the transcription factor Elongin during Drosophila wing tissue development. I have shown that Corto, ERK and one of its scaffold proteins MP1 form a complex on chromatin. This complex could regulate the recruitment on chromatin of Polycomb and Trithorax complexes in response to ERK signaling. Furthermore, I have shown that Corto and the elongation factor Elongin could both participate in the regulation of rhomboid, a gene involved in wing tissue development. Lastly, I studied the role of the interaction of Corto with some mRNA, one of these being the MP1 mRNA.
