Project Title:

Single-molecule microscopy reveals details of heterochromatin reorganisation at the onset of mouse ES cell differentiation

Project Summary:

In the last decade, spatial organisation of the genome has been recognised as one of the important factors linked to gene expression and cell identity. Although we have come a long way in describing how chromatin folds, it is still unclear what determines this structure and why it changes upon differentiation.

Mouse embryonic stem cells provide an excellent system to address these questions, since upon exit from naive pluripotency their genome undergoes a dramatic structural reorganisation. I employ single-molecule microscopy methods to study heterochromatin structure and dynamics in live mESCs and at the onset of their differentiation, focussing on the role of heterochromatin protein 1β (HP1β). By applying novel analysis methods, I test different biophysical models for heterochromatin compartmentalisation in mESCs.

Furthermore, I am developing super-resolution microscopy approaches to image chromatin-binding proteins and DNA in 3D throughout the entire nuclear volume of fixed cells. The protocol is designed to be compatible with single-cell Hi-C, enabling modeling of the genome structures of the imaged cells. Correlating the images and the structures will for the first time make it possible to obtain spatial sequence-specific information about the genome fold alongside protein localisation on a single-cell level. I hope that this method will shed light on the molecular functions of chromatin-binding proteins in their native context and help us understand the rules of genome organisation.