Status: Pending
The overall aim of this project is that of understanding how cell identity is maintained in proliferating cell types. During mitosis, transcription is reduced to marginal levels, chromatin compaction resets genome topology, and most transcription factors (TFs) are displaced from DNA. It thus remains to be understood how the different layers of the molecular architecture supporting the function of complex gene regulatory networks are faithfully re-established after each cell division. This includes understanding how the binding of TFs is re-established at an appropriate set of loci, and how these regulatory regions re-gain control over their target genes. Using Embryonic Stem Cells (ESCs), my past work highlighted how the mitotic functions of two nuclear receptors, Esrrb and Nr5a2, might be crucial in this regard. These TFs are retained at a subset of regulatory regions during division, a phenomenon known as “mitotic bookmarking”, which correlates with a fast re-activation of the putative targets of these elements. Recruitment of Esrrb and Nr5a2 at bookmarked regions depends on the recognition of specific sequences on DNA. Like other TFs, Esrrb and Nr5a2 displace nucleosomes to access their targets on DNA, and by doing so they contribute to maintaining nucleosome order during division at bookmarked loci. In turn, such preserved configuration might facilitate the gain of binding by other key ESC TFs in early G1. We will use high throughput genome editing to introduce libraries of synthetic regulatory elements carrying sites for bookmarking and non bookmarking TFs in the genome of ESCs, and leverage and footprinting techniques to study how nucleosome-mediated interactions may contribute to the reassembly of regulatory complexes in cells entering a new cell cycle, and ensure a fast and accurate resumption of cell-specific transcriptional programmes.
Submitted: 2024-02-12 17:20 · Last updated: 2024-03-27 09:05