Chromosomal Domains and DNA Replication

Group leader

During development, chromosomal domains of gene expression are progressively established concomitantly with active cell divisions. Before each division, cells have to copy their genome with a high fidelity to prevent cell death or the development of cancerous cells. This process is named DNA replication and starts at multiple specific sites (~ 100 000 in human cells) called replication origins. A spatiotemporal program controls the positioning and the timing of activation of replication origins during the S-phase of the cell cycle. Our aim is to identify molecular mechanisms involved in the establishment of this program.

To have a global vision of the replication of the human genome, we develop high through-put analyses (DNA microarrays and deep sequencing) in order to map replication origins and their timing of activation (Figure 1). Collaboration with bio-statisticians and bio-informaticians has allowed us to establish links between these maps and genomic data on chromatin structure and gene expression. We also use an avian model system (the DT40 cell line) which has the unique property to make homologous recombination with very high rates. This powerful genetic model system allows us to efficiently test hypotheses drawn from our genomic studies. We also use this model system to follow in single cell the dynamic of replication of targeted loci (Figure 2a, figure 2b).

The understanding of the pattern of duplication of eukaryotic genomes is essential. Indeed, DNA replication not only ensures genome stability but also coordinates the establishment of gene expression programs during development.

Figure 1 (click on the figure to enlarge): Map of the spatiotemporal program of DNA replication in the avian model cell line DT40. (A) Solexa single read profile obtained with a preparation of Short nascent strands (SNSs) characteristic of replication origins and aligned along a 250 Kb region of chromosome 1. Regions enriched correspond to replication origins (ORI). (C) Replication timing profile along chromosome 1. (B) Zoom-in on a portion of this chromosome. Early replicating regions and late replicating regions are shown in red and green respectively.

Figure 2a: The movie shows one cell replicating synchronously 2 tagged alleles (one image/4 min).
The chicken B-lymphoid DT40 cell line is modified with a TetO/TetR-EGFP labelling system allowing to follow the replication dynamic of individual loci in single living cells. © Bénédicte Duriez

Figure 2b: The graph shows the corresponding GFP intensities quantified from the above movie.

Current research themes:

  • Identification of cis-regulatory motifs and trans-factors involved in the spatial program of DNA replication.
  • Identification of cis-regulatory motifs and trans-factors involved in the temporal program of DNA replication.
  • Exploring the role of the temporal program in the establishment of chromosomal domains.
  • Single cells analyses of replication dynamic.

The group is supported by the "Fondation ARC pour la recherche sur le cancer"

The group is part of the Labex “Who am I?”

Sélection de publications

The spatiotemporal program of DNA replication is associated with specific combinations of chromatin marks in human cells. Picard F, Cadoret JC, Audit B, Arneodo A, Alberti A, Battail C, Duret L, Prioleau MN. 
PLoS Genet. 2014 May 1;10(5):e1004282.
Abstract

G4 motifs affect origin positioning and efficiency in two vertebrate replicators.
Valton AL, Hassan-Zadeh V, Lema I, Boggetto N, Alberti P, Saintomé C, Riou JF, Prioleau MN.
EMBO J. 2014 Feb 12. [Epub ahead of print]
Abstract

USF binding sequences from the HS4 insulator element impose early replication timing on a vertebrate replicator.
Hassan-Zadeh V, Chilaka S, Cadoret JC, Ma MK, Boggetto N, West AG, Prioleau MN.
PLoS Biol. 2012;10(3):e1001277. Epub 2012 Mar 6.
Abstract

Interplay between DNA replication and gene expression: a harmonious coexistence.
Maric C, Prioleau MN.
Curr Opin Cell Biol. 2010 Jun;22(3):277-83. Epub 2010 Apr 2. Review.
Abstract

Genome-wide studies highlight indirect links between human replication origins and gene regulation.
J-C. Cadoret, F. Meisch, V. Hassan-Zadeh, I. Luyten, C. Guillet, L. Duret, H. Quesneville & M-N. Prioleau
Proceedings of the National Academy of Sciences of the USA (2008), October 6, 2008
Abstract

Last modified 15 January 2018

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