Project : How is transcription controlled during DNA replication ?
02/01/2023 - 30/10/2027
Transcription and replication occur on the same DNA strand and the transcription process is one of the main source of obstacles for the replication machinery. Yet, how the transcription process impacts on DNA replication remains poorly understood and several hypotheses are in vogue:
1. Transcription machineries act as roadblocks for the replisome;
2. the opening of the DNA duplex during transcription generates topological constraints forming an obstacle for replisome progression;
3. Transcription by-products such as RNA:DNA hybrids hinder DNA replication.
Whereas the harmful effects of transcription on DNA replication are well documented when cells are submitted to exogenous replication stress (genotoxic agents) and in pathological conditions (specific mutations), interferences between both processes are very limited under physiological conditions. This implies a tight coordination between DNA replication and transcription that drastically minimizes conflicts between both processes.
The aim of my project is to understand how cells are able to coordinate both processes, and more specifically the involvement of the S-phase checkpoint in limiting transcription-replication conflicts. Indeed, we recently discovered that the S-phase checkpoint kinase Mec1/ATR transiently shutdowns transcription by promoting RNAPII degradation (Poli et al., Genes Dev, 2016 ; Hurst et al., EMBO J, 2021 ; Kemiha et al., DNA repair, 2021). Our last paper showing that RNA:DNA hybrids prevent effcient replication fork restart is out (Heuzé et al., EMBO J., 2023).
Our first goal is to identify and characterize the targets of S-phase checkpoint kinases that are involved in transcription-replication coordination. The second goal is to investigate how the transcription process perturbs replication forks progression. At last, we will determine if chromosome organization contributes to minimizing interferences between both processes.
To tackle these questions, we take benefit from the yeast model Saccharomyces cerevisiae where genetic tools are powerful in combination with advanced molecular biology techniques (ChIP, transcriptome, DNA molecular combing,...) as well as cellular biology (single-cell and/or single molecule microscopy). Another goal is to test is the mechanisms identified in yeast are conserved in human cells.
If you are interested by these questions and you wish to learn more and/or join us, please contact me ! (jerome.poli[@]igh.cnrs.fr)
