Dear All

I would like to cordially invite you to the Nencki Institute Seminar which will take place on the 30th of November at 3pm. We will host dr Aleksandra Pękowska (Head of the Dioscuri Centre for Chromatin Biology and Epigenomics, Nencki Institute of Experimental Biology PAS). Her habilitation is processed by the Scientific Council of the Nencki Institute of Experimental Biology. She will present her lecture entitled: "Chromatin structure in mammalian cell nuclei: developmental dynamics, contribution to the control of gene expression and mechanisms of control"

Abstract

DNA regulatory elements, including promoters, enhancers, and insulators, control gene expression, thereby contributing to the setup of cell identity during development.

The functional dialogue between DNA regulatory elements relies partly on establishing physical proximity between the regulatory sequences. However, the mechanisms that warrant the specificity of contacts between promoters and enhancers have not been fully resolved.

Topologically Associating Domains (TADs) are megabase-sized genomic intervals of preferential genomic contacts. By delineating cognate promoter-enhancer pairs, TADs are implicated in the functional interplay between cis-regulatory elements. The formation of TADs critically relies on the concert action of cohesins and CTCF, an eleven-zinc finger insulator protein. In the process of loop extrusion, cohesins tether sequences to each other. CTCF blocks loop extrusion thereby establishing borders of TADs. CTCF-enriched TAD boundaries frequently form a strong interaction referred to as architectural loops.

In my postdoctoral work, we combined high-throughput sequencing approaches, including in-situ Hi-C and computational tools, to address how cohesins and CTCF regulate genome topology during cell activation and differentiation. In the presentation, I will show the timing of the maturation of chromatin structure and the formation of architectural loops during the earliest stages of mammalian development. Furthermore, I will present data highlighting the central role of cohesin in the generation of TADs and our results connecting cellular energy consumption to cohesin action on chromatin. Finally, I will show how tissue-specific active enhancers and CTCF impact genome topology to increase interactions with their cognate promoters.

The lecture will be followed by a get together.

Best regards,
Grażyna Mosieniak