Unit and global news

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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Effect of Mismatch repair deficiency on metastasis occurrence in a syngeneic mouse model

This work, led by P. Laplante in Kannouche’s team, shows how mismatch repair deficiency causes high mutation rates and microsatellite instability (MSI-H), linked to immune infiltration and immunotherapy response.
A syngeneic MSI breast cancer mouse model with Msh2 knockout showed reduced metastasis and immune gene enrichment. Aggressive hybrid epithelial-mesenchymal signatures appeared only in metastatic MSI-H tumors. Immature myeloid cells at tumor sites suggest unique immune responses beyond T-cell activation in MMR deficiency.

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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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Genomic mutation landscape of skin cancers from DNA repair-deficient xeroderma pigmentosum patients

This article is a collaboration of the Kannouche team with the Gustave Roussy’s team of S. Nikolaev. Xeroderma pigmentosum (XP) is caused by mutations in NER genes or DNA polymerase η, leading to a greatly increased skin cancer risk.
Analysis of 38 XP skin cancer genomes reveals that NER activity drives mutation rate variability and that transcription-coupled NER reduces intergenic mutations.
The findings clarify the genetic basis of skin cancer risk in XP.

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