New insights into cooperation of micro- and nano-scale elementary structural chromatin units in decision-making on DNA damage repair pathway (NANOREP)

• Applicant: Professor Dr. Michael Hausmann
• Subject Area: Nuclear Medicine, Radiotherapy, Radiobiology ; Biophysics
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 432117611

It is a long standing open question to which extent genome architecture influences both chromatin sensitivity to DNA double strand break (DSB) induction and efficiency of their repair or the decision on the repair pathway at a given damage site, respectively. We propose that functionally correlated genome architecture primarily determines the architecture of repair foci, which, in turn, regulate post-damage chromatin reorganization at DSB sites and their accessibility for repair-pathway specific proteins. This hypothesis does not exclude that the availability of repair proteins at the damaged site has further influence on the development of chromatin re-organization and architecture, since molecular interaction forces may in general be responsible for the process. So cell lines used as model systems which are known to have a different ground-level of repair proteins should show a different time course in genome architecture development. A critical point in DSB repair – the decision making for a certain repair pathway at each particular DSB – would be executed on structural basis if our hypothesis holds. Preliminary results recently published have given hints towards its verification. Multi-scale (micro→nano) differences of genome architecture among cancer and non-cancer cell types and its subsequent development after DNA damage induction may then explain, at least partially, cell type-specific and damage site typical repair processes, which finally might be an answer to cancer cell response to radiotherapy or in general radio-sensitivity. In this suggested project we will focus our investigations on basic research towards this application aspect studying molecular foci of γH2AX phosphorylation sites and selected proteins (53BP1, MRE11, Rad51, MRI) in detail after specific fluorescence labelling. These foci will be investigated in relation to their chromatin environment labelled by heterochromatin or euchromatin specific antibodies in combination with uniquely binding oligonucleotides (e.g., ALU, L1 sequences). Synergistic cooperation of well-established Brno and Heidelberg groups, employment of top-tech technologies (e.g. single-molecule localization nanoscopy, specific nano-probing of chromatin, etc.), and newly developed mathematical approaches for data evaluation, offer a unique possibility to test our hypotheses.

• DFG Programme: Research Grants
• International Connection: Czech Republic
• Partner Organisation: Czech Science Foundation
• Cooperation Partner: Martin Falk, Ph.D.