Periodic Reporting for period 5 - TOPOmics (Global dynamics of topoisomerase-induced DNA breaks)
Berichtszeitraum: 2021-02-01 bis 2021-12-31
The DNA of the human genome is very long, about 2 meters, but it is confined in each of our cells to the volume of the nucleus, a tiny sphere only about 10 microns in diameter. Obviously, this is only possible because DNA is coiled and packed into highly complex structures. In fact, the very structure of DNA, a double helix, already confers an inherent degree of coiling. Accessing genetic information, either for continuous expression, or at specific moments for its duplication and distribution during cell division, is therefore a major challenge; aberrant coils, knots and other topological problems inevitably appear. Topoisomerases are highly specialized enzymes that solve these topological problems, but use a cut-and-reseal mechanism that, when uncontrolled, can lead to the generation of DNA breaks that can compromise cell survival and the stability of the genome. This aberrant action of topoisomerases, in addition to being a potential endogenous source of DNA damage, constitutes the therapeutic basis for a series of widely used antitumor compounds that target the particularly active genome of cancer cells by “poisoning” topoisomerase activity. Imbalances in DNA topoisomerase activity can therefore compromise cell survival and genome integrity, entailing serious consequences for human health, such as developmental and degenerative problems and, very importantly, neoplastic transformation processes and their subsequent response to treatment.
This project aimed at acquiring a comprehensive picture of the dynamics of topoisomerase activity, how it is regulated to integrate different aspects of genome dynamics, how an imbalance in these processes can lead to the appearance of pathological DNA breaks, and how cells specifically respond to these lesions to maintain genome stability.
This project aimed at acquiring a comprehensive picture of the dynamics of topoisomerase activity, how it is regulated to integrate different aspects of genome dynamics, how an imbalance in these processes can lead to the appearance of pathological DNA breaks, and how cells specifically respond to these lesions to maintain genome stability.
We have developed novel methods to identify and isolate different intermediates in the catalytic metabolism of DNA topoisomerases and DNA breaks induced by their aberrant action. We have used these methods to generate genome-wide maps of regions where the different intermediates of topoisomerase function accumulate. We have found that, by generating excessive DNA coiling, transcription provides the “fuel” for topoisomerase activity, while the tridimensional organization of the genome provides the framework in which it operates. This generates a complex regulatory network that is used to fine-tune gene expression. However, it also generates regions that are particularly “fragile” and can lead to translocations associated with cancer development.
Furthermore, we have performed proteomic and genetic screenings that have allowed us to delineate the different pathways specifically involved in the cellular response to topoisomerase-induced DNA breaks. The results uncover a highly regulated hierarchical structure that tries to minimize DNA processing to avoid mutations and genome rearrangements. Disturbing this regulation results in high levels of genome instability and cancer predisposition. We have also identified a new factor, ZATT, involved in the cellular response to topoisomerase-induced DNA breaks, and characterized its specific function in this process and the physiological implications of disturbing its function.
Furthermore, we have performed proteomic and genetic screenings that have allowed us to delineate the different pathways specifically involved in the cellular response to topoisomerase-induced DNA breaks. The results uncover a highly regulated hierarchical structure that tries to minimize DNA processing to avoid mutations and genome rearrangements. Disturbing this regulation results in high levels of genome instability and cancer predisposition. We have also identified a new factor, ZATT, involved in the cellular response to topoisomerase-induced DNA breaks, and characterized its specific function in this process and the physiological implications of disturbing its function.
We have uncovered novel mechanisms of transcriptional regulation mediated by the topological state of DNA. This mechanism extends the role of topoisomerases from the classical view of them being mere facilitators of DNA transactions to a central role in the regulation and integration of key aspects of genome metabolism.
We have contributed to the emerging topic of topoisomerase-induced DNA breaks as important drivers of cancer.
We have uncovered ZATT as a novel factor involved in the metabolism of topoisomerase-induced DNA breaks. Interestingly, it defines a pathway to deal with these lesion that, in contrast to the classical view, does not require topoisomerase proteolytic degradation.
We have contributed to the emerging topic of topoisomerase-induced DNA breaks as important drivers of cancer.
We have uncovered ZATT as a novel factor involved in the metabolism of topoisomerase-induced DNA breaks. Interestingly, it defines a pathway to deal with these lesion that, in contrast to the classical view, does not require topoisomerase proteolytic degradation.