The DNA contained in one single cellular nucleus is 2 meters longs when stretched on a linear scale. Thus, fitting in a nucleus that is usually not bigger than 2 micrometers, requires that DNA has a high degree of compaction (1000000 times!!) and to achieve this the genome needs to be organized at several levels inside the nucleus. A correct genome organization is crucial to guarantee its proper function and stability. One crucial aspect of genome organization is anchoring of DNA to the nuclear lamina (NL), a scaffold that provides mechanical sustain to the nucleus. What controls the interaction between DNA and the NL is still a mystery. Among several proteins proposed to have a role in genome organization DNA topoisomerases have recently received particular attention. These enzymes can promote the relaxation of DNA that usually undergoes to substantial torsional stress during physiological processes inside the nucleus. By removing torsion from DNA, Topoisomerases can also control high order chromatin structures and favor and disfavor DNA compaction. DNA Topoisomerases are currently targeted in chemotherapy, thus understanding its biological function and interaction partners, especially in the context of 3D genome organization is very important to guarantee the development of new therapeutical approaches and identify potential additional targets to achieve more effective combinatorial therapies.
The goal of this project was to understand the relationship between DNA Topoisomerases and genome interaction with the nuclear lamina. DNA Topoisomerases were investigated for a potential role in controlling DNA-NL interaction using a specific technique called pA-DamID. I also tried to directly measure the torsional stress on chromatin, identifying the effects of both local and genome wide chromatin context in modulation of torsional stress and DNA structures that are topology dependent.
