The cells of the digestive tract first, then those of other tissues after systemic passage, may be damaged by genotoxic agents, coming from food contaminants or genotoxins formed in the intestine by commensal flora or by pathogens
Specific lines of research
Cells have to protect their genetic material in order to maintain their activities. Among the DNA damage, induced directly or indirectly, there are changes in the bases (adducts, oxidation,...) and / or DNA breaks (single-strand or double-strand breaks). The double-stranded breaks (DSB) are considered the most toxic form of DNA damage.
A causal link was established between DNA damage, mutagenesis and carcinogenesis. For example:
(i) aflatoxin B1, which forms adducts on guanines, is a known liver carcinogen;
(ii) certain pesticides, probably inducing DNA damage by oxidation of the bases, are carcinogenic;
(iii) recently, Colibactin, a substance produced by bacteria, some commensal E. coli, has been described as a genotoxic agent, probably via the production of DSB, although the mechanism has not been fully characterized.
It is therefore important to control exposure to genotoxic substances, and follow DNA damage that may result from such exposure. For this purpose, we study and characterize genotoxic substances (pesticides, nanoparticules, genotoxins…) through specific assays (comet assays, DSB analysis through well-known biomarkers – γH2AX, 53BP1). We are also interested in analyzing the effects of genotoxic substances, particularly by following the cell destiny (DNA damage and repair analysis, cell cycle checkpoint, cell death, senescence…). Finally, we are highly involved in the development of genotoxicity bioassays as well as the biotracers development, in order to follow the genotoxic effects in living cells and in real time.
Our main goal is to develop biotracers and bioessays to detect, track and characterize the DNA damage, directly in living cells. This will help to determine the genotoxicity of substances/contaminants -known or unknown, and help in the prevention and/or diagnosis of exposure to genotoxic to assess the risk of carcinogenesis.
We propose in particular to develop tools to monitor DSB. The formation of γH2AX foci (histone H2AX phosphorylation) is the most sensitive test to detect DSB, measure the integrity of the genome, and is therefore widely used nowadays. As DSB can be generated directly or indirectly (stop of forks replication in front of lesions) after various genotoxic stresses, the dynamic monitoring of theγH2AX foci formation may help to determine the genotoxic potential of a compound administered to cells in culture. Thus, the γH2AX marker is a tool with a great potential, for many applications from human health to environmental protection. We are working to the development of a γH2AX biotracer to study DSB in real time and in living cells (project supported by an ANR grant). We are also working on bioassays to characterize the genotoxic mechanisms (type of DNA damage, repair mechanisms involved) of the tested substances.
In line with the objectives of the UMR 1331 TOXALIM, our research aim to provide answers to the questions being raised about the health effects of exposure to genotoxic as well as tools to characterize these substances .
Our work contributes primarily to the strategic objectives defined by INRA:
· Axis B: improving human nutrition, the health of consumers
· Axis D: develop research and produce the generic data for the knowledge of life.