Modeling gene expression : RNA silencing and epigenetics

Orateur : Daniel JOST (Laboratoire de Physique - Ecole Normale Supérieure de Lyon)

Different cells of the same species have the same genome but might express different genes depending on their environment, on their developmental stage or on their history. Studying the key principles of how genes are regulated is crucial in our global understanding of cell and organism behaviors including development, disease and evolution.In this seminar, I will present my efforts on modeling some aspects of gene regulation, in particular in the context of post-transcriptional regulation by small non-coding RNA (sRNA) and of epigenetic regulation. In a first part, I will describe the different models I developed on sRNA regulation using methods from statistical physics and information theory. In particular, our approach, in combination with experiments or analysis of evolutionary data, had revealed novel properties of RNA silencing like a fluctuation-buffering effect played by the many weak targets of a given sRNA in eucaryotes and a cooperative interaction between translation and sRNA regulation in bacteria.In a second part, I will present my current and future works on modeling epigenetic regulation at different scales. At the genome scale, using polymer models, we find that epigenetic-controlled interactions between DNA region might explain the global organization of chromatin inside the nucleus. At the gene scale, I will briefly describe my CNRS research project on the role of stochasticity in the epigenetic regulation.

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