DNAcheck · Mechanistic analysis of DNA damage signaling and bypass upon replication of damaged DNA template in human cells.
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-10-01 → 2020-09-30
- EU contribution
- €170,122
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Mechanistic analysis of DNA damage signaling and bypass upon replication of damaged DNA template in human cells.
The genetic information encoded by DNA is constantly threatened by endogenous or exogenous sources of damage. To safeguard the genome against these insults, cells have evolved DNA damage checkpoints that sense the presence of damaged DNA, block cell cycle progression and ensure that DNA is fully repaired before resuming the cell cycle. However, in many cases, unrepaired lesions remain in the DNA when cells enter S-phase. In this scenario, cells employ DNA damage tolerance mechanisms to complete genome replication and prevent fork breakage. Importantly, these pathways are not restricted to the site of stalling but can also function behind the fork at single-stranded(ss)DNA gaps originated by re-priming of DNA synthesis downstream of lesions. While it is well known that the accumulation of single-stranded DNA (ssDNA) is the signal that riggers the checkpoint response, it is less clear how and where ssDNA actually arises. Generally, it is assumed to accumulate at stalled replication forks by an uncoupling between replicative helicase and polymerase movement. However, recent evidence found in budding yeast support a model where, in response to polymerase-blocking lesions, replication forks do not stall but recover efficiently by re-priming downstream of the lesions, thus leaving ssDNA gaps behind the fork. It is currently unknown whether this model also applies to vertebrate cells. Hence, this project aimed to address the fundamental question of how DNA damage is sensed during genome replication in human cells.
Data: CORDIS, © European Union
Project objective
The genetic information encoded by DNA is under constant attack from both endogenous and exogenous sources of damage. To ensure genome stability and prevent disease, cells use global signaling networks to sense and repair DNA damage. One particularly serious problem is when the replication machinery encounters lesions remaining in the template DNA. In this scenario, cells employ damage bypass mechanisms to complete genome replication and prevent fork breakage. Importantly, these pathways are not restricted to the site of stalling but can also function behind the fork at single-stranded DNA (ssDNA) gaps originated by the re-priming of DNA synthesis downstream of lesions. While it is very well known that ssDNA is the molecular signal that triggers the checkpoint response, it is less clear how and where ssDNA actually arises. Generally, it is assumed to accumulate at stalled replication forks, either by an uncoupling between replicative helicase and polymerase movement or between leading and lagging strand synthesis. However, in a recent study in budding yeast, I found that ssDNA gaps left behind replication forks, and extended by processing factors such as the exonuclease EXO1, constitute the predominant signal that leads to checkpoint activation in response to damaged DNA templates during S phase. Whether this mechanism of checkpoint activation is conserved from yeast to humans remains unexplored. Hence, using a unique set of multidisciplinary approaches, this project aims to address the fundamental question of how DNA damage is sensed during replication in human cells. Interestingly, not only ssDNA gap processing seems important for checkpoint signaling but also for the template switching mechanism of damage bypass. Therefore, this project will also study the function of EXO1 and its association with PCNA at postreplicative ssDNA gaps in order to shed light on the poorly understood mechanism of template switching.
Original text from CORDIS.
Participants
- UNIVERSIDAD DE SEVILLA · SevillaCoordinatorSpain
Links
Data: CORDIS, © European Union