NUCLEASE REGULATION · Control of structure specific endonucleases and implications in the biology of cancer
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-02-01 → 2009-01-31
- EU contribution
- €80,000
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - NUCLEASE REGULATION (Control of structure specific endonucleases and implications in the biology of cancer)
Structure-specific endonucleases are essential for the processing of secondary DNA structures and preventing genomic instability. However, because these enzymes cleave the DNA double helix, they can be viewed as double edge swords. Indeed, unless properly controlled structure-specific endonucleases may in some cases lead to, rather than prevent, chromosome instability and ultimately tumourigenesis. Therefore, complex control mechanisms must exist to ensure a proper coordination and usage of multiple structure-specific endonucleases in the cell. Our research focuses on understanding how structure-specific endonucleases are controlled. For this we have been combining studies on these enzymes in fission yeast, a powerful model system to investigate genome maintenance mechanisms, and in human cells. We have established to key findings during the course of this project: 1) We have unravelled a novel mode of regulation of the Mus81-Eme1 structure-specific endonuclease in fission yeast. Mus81-Eme1 is required to process DNA structures, such as Holliday junctions, that covalently link chromosomes and which, if left unresolved, will prevent the proper segregation of chromosomes into to the daughter cells. We have found that Eme1 is phosphorylated in a Rad3-dependend manner and that, although this is not required in the general response to gentoxic drugs, it is critical for preventing spontaneous genome instability in absence of the Rqh1 helicase. 2) We have identified and characterised the human ortholog of the yeast Slx4 protein. We show that SLX4 is a subunit of a Holliday junction resolvase that interacts with multiple DNA repair/recombination endonucleases. We propose that SLX4 acts as a coordination and control unit for structure-specific endonucleases in human cells and that it has pivotal functions in several genome maintenance mechanisms. Considering the marked spontaneous and drug induced phenotypes associates with depletion of SLX4 in human cells and the variety of DNA repair/recombination pathways it appears to be involved in, we believe that the identification of human SLX4 opens new avenues for understanding the processes involved in the maintenance of genome stability and the prevention of the onset of cancer and other human diseases.
Data: CORDIS, © European Union
Project objective
Structure-specific endonucleases are key players in the maintenance of genome integrity. They act as specialized surgical tools for the processing of secondary DNA structures generated during important DNA repair and recombination events. However, cleaving DNA opens windows of opportunity for the occurrence of potentially dangerous chromosome rearrangements at the origin of cancer.The action of structure-specific endonucleases must therefore be tightly coordinated with downstream events that restore the full integrity of the chromosome. Additional challenge for the cell stems from the fact that for many of these nucleases the minimal structural requirement for cleaving DNA is a junction between double-strand and single-strand DNA.Therefore, in addition to controlling these enzymes in the context of their physiological reaction, the cell must ensure that they do not act randomly on structures generated during other DNA transactions associated with DNA unwinding. Despite their fundamental nature, the mechanisms that control structure-specific endonucleases remain poorly understood.This research project proposes to tackle this fundamental question by focusing on a conserved class of eukaryote heteromeric structure-specific endonucleases, each involved in sever al DNA repair and recombination pathways. A detailed analysis of the regulation of these endonucleases will be carried out throughout the cell-cycle and in response to genotoxic stresses in the fission yeast Schizosaccharomyces pombe; a proven model system for the analysis and understanding of evolutionary conserved processes involved in genome maintenance in higher eukaryotes.The remarkable investigational potential of S. pombe will allow to combine genetic and cellular analysis with proteomic and biochemical studies. Results from our investigations in yeast will provide a platform to extend our analyses to mammalian cells, with a constant focus on assessing their relevance in the context of cancer biology.
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE · PARISCoordinatorFrance
Links
Data: CORDIS, © European Union