The Physics behind Cellular Memory: Droplets, Copolymers and Micelles

• Applicant: Professor Dr. Helmut Schiessel
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics ; Experimental and Theoretical Physics of Polymers
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 504905334

When cells divide in two copies of themselves, not only do they have to duplicate their DNA molecules, they also have to restore the epigenetic state of the mother cell. With half of the epigenetic marks lost during cell division, it is not clear how this can be achieved. In this project, we use computer simulations and theoretical approaches to show that soft matter physics provides the cell with the necessary tools to restore the epigenetic state. This includes the formation of protein condensates through a new mechanism we call polymer-assisted condensation. We model the chromosome as a block copolymer, with the different blocks representing different types of chromatin (euchromatin, constitutive and facultative heterochromatin), which are characterized by the presence or absence of certain epigenetic marks on the DNA-packaging histone proteins. Heterochromatin induces the formation of various droplets in which enzymes then robustly restore the missing epigenetic marks.

• DFG Programme: Research Grants
• International Connection: USA
• Co-Investigators: Dr. Holger Merlitz, Ph.D.; Professor Dr. Jens-Uwe Sommer
• Cooperation Partner: Professor Dr. Joshua Lequieu