Lab life

Genome-wide measurement of DNA replication fork directionality and quantification of DNA replication initiation and termination with Okazaki fragment sequencing

OK-seq is a technique that sequences strand-specific Okazaki fragments to map replication initiation and termination in mammalian genomes. It quantifies fork directionality, revealing replication dynamics at high resolution. N. Petryk team contributes to this work to provide detailed protocols for OK-seq in human cells and yeast, alongside bioinformatics pipelines.

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Monitoring Chk1 kinase activity dynamics in live single cell imaging assays

The ATR/Chk1 pathway regulates cell cycle progression, especially during DNA damage by inducing arrest for repair. Beyond damage response, Chk1 prevents premature mitosis during normal S phase, maintaining genome integrity. The Gavet team developed a FRET-based reporter to monitor Chk1 activity in live single cells with high sensitivity. This tool reveals Chk1 dynamics during normal and stressed conditions.

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Changes in the architecture and abundance of replication intermediates at UV-stalled replication forks in human cells

This is a collaborative effort of the Kannouche and Mazon/LeCam teams of the unit. DNA lesions during S phase challenge genome stability, managed by DNA damage tolerance (DDT) via TLS polymerases or recombination. Using electron microscopy, we show TLS polymerase η acts at replication forks to prevent gaps after UV damage. We outline a timeline of UV damage tolerance highlighting polη’s crucial role in DNA synthesis continuity.

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Retraite de l’unité 16 Octobre 2025

La retraite de l’unité aura lieu le 16 Octobre 2025 à la cité U (Fondation Deutsch de la Meurthe). RDV à 8:45!

Fondation Deutsch de la Meurthe au CIUP (RER cité U).

Attention ! :

– L’Accès Piéton se fera par le 37 Boulevard Jourdan, 75014 PARIS
– L’Accès voiture se fera par les 27/29/31 Boulevard Jourdan 75014 PARIS

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Chk1 dynamics in G2 phase upon replication stress predict daughter cell outcome

The Gavet team developed a FRET-based sensor to specifically monitor Chk1 activity during replication stress (RS).
Basal Chk1 activity during S phase depends on replication origin firing, with RS triggering stepwise Chk1 over-activation that delays S-phase.
Chk1 is inactivated upon replication completion but reactivates in some G2 cells to block premature mitosis.
Cells can override active Chk1 signaling to enter mitosis, revealing checkpoint adaptation.

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