Invitée par l’équipe Prioleau, Anne-Laure Valton (GenPhySE – INRAE Toulouse) présentera un séminaire IJM sur le thème :
Chromosome folding and gene expression
Résumé :
Chromosomes are the physical templates for many crucial molecular functions in the nucleus: gene expression, DNA repair and DNA replication. During interphase, chromosomes are folded by two main mechanisms which are phase separation and loop extrusion. The phase separation mechanism separates chromosomes into active (A) and inactive (B) compartments which respectively correspond to euchromatin and heterochromatin. At the same time, the loop extrusion mechanism, driven by cohesin complexes, forms Topologically Associating Domains (TADs) or loop domains. Cohesin actively extrudes DNA until it gets blocked at chromatin boundaries occupied by CTCF. TAD boundaries represent important functional and structural elements of the mammalian genome, but what constitutes such elements and how it regulates genome functions are only partly understood. We identify two types of chromatin boundaries, the active TSS and TTS that, together with the well-established CTCF-bound boundaries, define the dynamics of cohesin localization and mobility along chromosomes. Disturbing this cohesin traffic pattern, by removing CTCF barriers, renders cells sensitive to knock-out of genes involved in gene regulation. This complex pattern of cohesin movement along chromatin guides enhancer-promoter interactions and contributes to the localization of transcription and RNA processing factors to active genes.
Le séminaire aura lieu vendredi 1e mars à 11h45 en salle François Jacob (Institut Jacques Monod – 15 rue Hélène Brion 75013 Paris).
