Year 5

During the nearly 5 years of the CIRM award  we have now rebuilt our microscopes dedicated to image single molecules in live cells and developed microscopes and technologies to transpose these methods to developing embryos and more complex tissues.  In addition to the microscopes, part of the group has engaged in developing computational tools to analyze and optimize our images.  Our work on nuclear organization in ES cells is now well under way.  We have developed methods to understand how transcription factors are maintained on chromatin during cellular division which is essential to study the stability of a transcriptional program during cellular fate decisions as it occurs concomitantly with the cell growth.  Studying the organization in space and time of a complex lick CTCF and Cohesin is also central to our understanding how how TADs are formed and maintained an ultimately how enhancers are potentiated to act on specific genes at a particular time during cell fate decisions.  All these studies will now massively benefit from our ability to make single molecule measurements in embryos and the new tools we have developed to directly measure loop formation in live cells.  In 2019 we published 2 papers that demonstrated that the nuclear exploration geometry of CTCR is dependent on its interaction with rna and essential for its efficient target search.  Our results were published and will now open the door to a new field of study in which we now have access to the mechanism regulating protein interactions in live cells.  Our work characterizing the Pre-Initiation Complex dynamics and kinetics is expanding from the mediator to TFIID and SAGA.  We have developed a strong program dissecting the weak and transient interactions mediated by intrinsically disordered domains and mediating local clusters of proteins in the nucleoplasm  We are currently exploring their functional relevance for transcription regulation.  During the last year we have developed a strong progra