Notre-Dame-des-Landes, France
Notre-Dame-des-Landes, France
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Benzina S.,CEA Grenoble | Benzina S.,French Institute of Health and Medical Research | Benzina S.,University Grenoble Alpes | Pitaval A.,CEA Grenoble | And 16 more authors.
Cellular and Molecular Life Sciences | Year: 2015

A general radioprotective effect by fibroblast growth factor (FGF) has been extensively described since the early 1990s; however, the molecular mechanisms involved remain largely unknown. Radiation-induced DNA double-strand breaks (DSBs) lead to a complex set of responses in eukaryotic cells. One of the earliest consequences is phosphorylation of histone H2AX to form nuclear foci of the phosphorylated form of H2AX (γH2AX) in the chromatin adjacent to sites of DSBs and to initiate the recruitment of DNA-repair molecules. Upon a DSB event, a rapid signaling network is activated to coordinate DNA repair with the induction of cell-cycle checkpoints. To date, three kinases (ATM, ATR, and DNA-PK) have been shown to phosphorylate histone H2AX in response to irradiation. Here, we report a kinome-targeted small interfering RNA (siRNA) screen to characterize human kinases involved in H2AX phosphorylation. By analyzing γH2AX foci at a single-nucleus level, we identified 46 kinases involved either directly or indirectly in H2AX phosphorylation in response to irradiation in human keratinocytes. Furthermore, we demonstrate that in response to irradiation, the FGFR4 signaling cascade promotes JNK1 activation and direct H2AX phosphorylation leading, in turn, to more efficient DNA repair. This can explain, at least partially, the radioprotective effect of FGF. © 2015 The Author(s).

Decordier I.,Vrije Universiteit Brussel | Papine A.,IMSTAR | Vande Loock K.,Vrije Universiteit Brussel | Plas G.,Vrije Universiteit Brussel | And 2 more authors.
Mutagenesis | Year: 2011

For many years, the analysis of micronuclei (MN) has been successfully applied to human biomonitoring of in vivo genotoxin exposure and provides a sensitive and relatively easy methodology to assess genomic instability. However, there is a need for automation of MN analysis for rapid, more reliable and non-subjective MN detection. In this review, we evaluate the application of automated image analysis of the in vitro cytokinesis-block MN assay on human lymphocytes for human biomonitoring, starting with the requirements that should be fulfilled by a valid and efficient image analysis system. Considering these prerequisites, we compare the automated facility developed in the framework of the European Union-project NewGeneris with other already published systems for automated scoring of MN. Although the automated scoring of MN is now put into place, extension to other cytome assay end points such as apoptosis, necrosis, nuclear buds and nucleoplasmic bridges would greatly enhance the specificity and sensitivity of future biomonitoring studies. Inclusion of these end points would also allow an automated approach to in vitro genotoxicity testing. In addition, automated scoring of the MN assay in exfoliated buccal cells would be very beneficial for large-scale biomonitoring studies, as cells can be collected in a minimally invasive manner. © The Author 2010. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved.

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