Biology subjects

Cadoret, J.-C.

Publications and source records attributed to Cadoret, J.-C..

6 recordsLinked to original sources

bioRxiv2025

PARP inhibitors affect the replisome and replication fork progression during a single S phase.

Poly(ADP-ribosyl)ation (PARylation) is a protein modification mostly synthesised and degraded by PARP1/2 and PARG enzymes, respectively. PARylation is involved in many covalent and non-covalent protein-protein interactions in the nucleus, making it a powerful form of molecular signaling in DNA metabolism. PARP inhibitors (PARPi) have shown efficacy in the treatment of Homologous Recombination (HR)-deficient cancers, yet the full range of molecular mechanisms underlying the activity of these drugs is not fully understood. Here, we decipher the direct consequences of PARPi-induced loss of PARylation on DNA replication. First, PARPi treatment during a single S phase induces replicative stress, delays S phase progression and causes genome-wide replication timing changes of disease-associated regions. These DNA replication alterations appear to be caused by an accumulation of SSBs in the DNA replicative template when PARylation is inhibited, which then seems to lead to one-ended DSBs and fork collapse during S phase. Second, PARPi deplete FANCD2-I, BRCA, monoubiquitinated PCNA and RAD18 proteins from the replisomes. The two PARPi tested then appear to modulate the choice of fork restart mechanisms and influence replisome dynamics in different ways. Taken together, our study highlights the common and unique primary effects of two PARPi on unperturbed DNA replication in human cells. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=169 SRC="FIGDIR/small/639283v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@298f8dorg.highwire.dtl.DTLVardef@8f8cbcorg.highwire.dtl.DTLVardef@60952forg.highwire.dtl.DTLVardef@e2700a_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

DBF4, not DRF1, is the crucial regulator of CDC7 kinase at replication forks

In eukaryotes, CDC7 kinase is crucial for DNA replication initiation and has been involved in fork processing and replication stress response. Human CDC7 requires the binding of either one of two regulatory subunits, DBF4 and DRF1, for its activity. However, it is unclear whether the two regulatory subunits target CDC7 to a specific set of substrates, thus having different biological functions, or if they act redundantly. Using genome editing technology, we generated an isogenic set of cell lines deficient in either one of the two CDC7-activating subunits: these cells are viable but present signs of genomic instability, indicating that both DBF4 and DRF1 can independently support CDC7 for bulk DNA replication. Nonetheless, DBF4-deficient cells show altered replication efficiency, including partial deficiency in MCM helicase phosphorylation and alterations in the replication timing of discrete genomic regions. Notably, we find that CDC7 function at replication forks is entirely dependent on DBF4 and not DRF1. Thus, DBF4 is the primary regulator of CDC7 activity, likely mediating most of its functions in unperturbed DNA replication and during replication fork processing upon replication interference.

biochemistry↗

bioRxiv2022

GNL3 regulates replication origin firing and protects stalled replication forks

DNA replication requires specific proteins that protect replication forks and so prevent the formation of DNA lesions that may damage the genome. Identification of new proteins involved in these processes is essential to understand how cancer cells tolerate DNA lesions. Here we show that human GNL3/nucleostemin, a GTP-binding protein localized mostly in the nucleolus and highly expressed in cancer cells, prevents nuclease-dependent resection of nascent DNA in response to exogenous replication stress. We demonstrate that inhibition of origin firing decreases this resection, indicating that the increased replication origin firing seen upon GNL3 depletion mainly accounts for the observed DNA resection. We show that GNL3 and DNA replication initiation factor ORC2 interact in the nucleolus and that the concentration of GNL3 in the nucleolus is required to limit DNA resection in response to replicative stress. We propose that the accurate control of origin firing by GNL3, possibly through the regulation of ORC2 sub-nuclear localization, is critical to prevent nascent DNA resection in response to replication stress.

molecular biology↗

bioRxiv2020

Low replication stress leads to specific replication timing advances associated to chromatin remodelling in cancer cells

DNA replication is well orchestrated in mammalian cells through a tight regulation of the temporal order of replication origin activation, named the replication timing, a robust and conserved process in each cell type. Upon low replication stress, the slowing of replication forks induces delayed replication of fragile regions leading to genetic instability. The impact of low replication stress on the replication timing in different cellular backgrounds has not been explored yet. Here we analysed the whole genome replication timing in a panel of 6 human cell lines under low replication stress. We first demonstrated that cancer cells were more impacted than non-tumour cells. Strikingly, we unveiled an enrichment of specific replication domains undergoing a switch from late to early replication in some cancer cells. We found that advances in replication timing correlate with heterochromatin regions poorly sensitive to DNA damage signalling while being subject to an increase of chromatin accessibility. Finally, our data indicate that, following release from replication stress conditions, replication timing advances can be inherited by the next cellular generation, suggesting a new mechanism by which cancer cells would adapt to cellular or environmental stress.

cancer biology↗

bioRxiv2020

USP9X deubiquitinase couples the pluripotency network and cell metabolism to regulate ESC differentiation potential

Embryonic stem cells (ESC) have the unique ability to differentiate into all three germ cell layers. ESC transition through different states of pluripotency in response to growth factor signals and environmental cues before becoming terminally differentiated. Here, we demonstrated, by a multi-omic strategy, that the deubiquitinase USP9X regulates the developmental potential of ESC, and their transition from a naive to a more developmentally advance, or primed, state of pluripotency. We show that USP9X facilitates developmental gene expression and induces modifications of the mitochondrial bioenergetics, including decreased routing of pyruvate towards its oxidation and reduced respiration. In addition, USP9X binds to the pluripotency factor ESRRB, regulates its abundance and the transcriptional levels of a subset of its target genes. Finally, under permissive culture conditions, depletion of Usp9X accelerates cell differentiation in all cell lineages. We thus identified a new regulator of naive pluripotency and show that USP9X couples ESRRB pluripotency transcriptional network and cellular metabolism, both of which are important for ESC fate and pluripotency.

cell biology↗

bioRxiv2019

New, easy, quick and efficient DNA replication timing analysis by high-throughput approaches.

DNA replication must be faithful and follow a well-defined spatio-temporal program closely linked to transcriptional activity, epigenomic marks, intra-nuclear structures, mutation rate and cell fate determination. Among the readouts of the DNA replication spatio-temporal program, replication timing (RT) analyses require complex, precise and time-consuming experimental procedures, and the study of large-size computer files. We improved the RT protocol to speed it up and increase its quality and reproducibility. Also, we partly automated the RT protocol and developed a user-friendly software: the START-R suite (Simple Tool for the Analysis of the Replication Timing based on R). START-R suite is an open source web application using an R script and an HTML interface to analyze DNA replication timing in a given cell line with microarray or deep-sequencing results. This novel approach can be used by every biologist without requiring specific knowledge in bioinformatics. It also reduces the time required for generating and analyzing simultaneously data from several samples. START-R suite detects constant timing regions (CTR) but also, and this is a novelty, it identifies temporal transition regions (TTR) and detects significant differences between two experimental conditions. The informatic global analysis requires less than 10 minutes.

genomics↗