Description du projet
Régulation de la tension de torsion de l’ADN au niveau de la lamina nucléaire
La transcription ou la réplication de l’ADN engendre une tension de torsion dans la double hélice. L’enzyme qui supprime ce stress est l’ADN topoisomérase I (Top1), une cible de la chimiothérapie anticancéreuse. La perte de l’activité de la Top1 entraîne une accumulation de tension de torsion dans les gènes transcriptionnels actifs et peut conduire à la formation de structures hybrides ADN/ARN non canoniques, appelées boucles R. L’équipe du projet a récemment montré que l’épuisement de Top1 conduit à la stabilisation des boucles R, en particulier dans les gènes ancrés à la lamina nucléaire. Cette observation suggère fortement que la fixation de l’ADN à la lamina nucléaire peut empêcher la dissipation de la tension de torsion. Le projet TorsionAtLamina, financé par l’UE, étudie la relation entre la tension de torsion, la Top1, les boucles R et la fixation de la lamina nucléaire, en utilisant des techniques de génomique développées dans le laboratoire hôte.
Objectif
When DNA is transcribed or replicated, torsional stress accumulates on the double helix. This tension must be dissipated by spreading it along the DNA fiber, or it must be removed altogether. One of the main factors responsible for the removal of such stress is DNA Topoisomerase I (Top1), an important target of cancer chemotherapy. When Top1 activity is lost, torsional stress accumulates on transcriptionally active genes and can lead to the formation of non-canonical DNA/RNA hybrid structures called R loops. These structures are emerging as important regulators of genome function and stability. By genome-wide mapping of R loops in human cells, I recently found that depletion of Top1 leads to a marked R loop stabilization, specifically on genes that are anchored to the nuclear lamina. This strongly suggests that attachment of DNA to the nuclear lamina may prevent dissipation of torsional stress, but how this works is still largely unclear. I propose to investigate the causal relationships between torsonal stress, Top1, R-loops and nuclear lamina attachment, taking advantage of a suite of unique genomics techniques developed in the host lab. Specifically, I will: 1) Develop two novel reporter assays to probe the effects of chromatin context (in particular lamina associated chromatin) and Top1 on torsional stress and R loop formation, at thousands of locations in the human genome. 2) Investigate if and how Top1 regulates DNA/nuclear lamina contacts by by means of a novel version of the powerful genome-wide DamID mapping method with much-improved time resolution. My expertise in Top1, R-loops and DNA topology combined with the unique genomics methodologies in the host lab, as well as their expertise in lamina-associated DNA, will lead to a unique synergy that should result in new insights into the relationship between nuclear organization, torsional stress and R loop formation. Moreover, it will yield new methods that will boost scientific progress in this field.
Champ scientifique
Programme(s)
Régime de financement
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinateur
1066 CX Amsterdam
Pays-Bas