Studying the DNA damage response in embryonic systems.
Lo Furno E, Recolin B, van der Laan S, Aze A, Maiorano D
Molecular bases of human diseases
Our group is generally interested in the regulation of the DNA Damage Response (DDR), and in particular in its regulation during the early steps of embryonic development. The main function of the DDR is to slow down, or arrest cell prolferation in the presence of DNA lesions (DNA breaks, telomer integrity, replication forks stall) so to avoid cell division in the presence of DNA damage and therefore avoid the propagation of mutations that are drivers of genomic instability. A strong genomic instability is a feature of cancer cells (telomeric fusions, trabnsocations, duplications, deletions). To date it is admitted that the majority of sporadic tumours are the consequence of mutations in DDR genes, which can also lead to the development of genetic diseases. Hence the DDR is currently considered as a major barrier to malignat transformation playing a key role in maintenace of genomic stability.
Lo Furno E, Recolin B, van der Laan S, Aze A, Maiorano D
Lo Furno E., Busseau, I., Aze, A., Lorenzi, C., Saghira, C., Danzi, M., Zuchner, S., Maiorano, D.
Maiorano D, El Etri J, Franchet C, Hoffmann JS
Jihane Basbous, Antoine Aze, Laurent Chaloin, Rana Lebdy, Dana Hodroj, Cyril Ribeyre, Marion Larroque, Caitlin Shepard, Baek Kim, Alain Pruvost, Jérôme Moreaux, Domenico Maiorano, Marcel Mechali, Angelos Constantinou
Aze A, Maiorano D
Benkafadar N, Menardo J, Bourien J, Nouvian R, François F, Decaudin D, Maiorano D, Puel JL, Wang J.
Kermi, C., Lo Furno, E., Maiorano, D
Hodroj D, Recolin B, Serhal K, Martinez S, Tsanov N, Abou Merhi R, Maiorano D
Hodroj, D., Serhal, K., Maiorano, D.
Lo Furno, E., van der Laan, S., and Maiorano, D.
Vanacker JM, Maiorano D.
Tsanov, N., Kermi, C., Delgado, J., Serrano, L., Maiorano D.
Kermi, C., Prieto, S., van der Laan, S., Tsanov, N., Recolin, B., Uro-Coste, E., Delisle, M-B., and Maiorano, D.
Tsanov, N., Kermi, C., Coulombe, P., Van der Laan, S., Hodroj, D., Maiorano, D.
Van der Laan, S., Maiorano, D.
van der Laan S, Golfetto E, Vanacker JM, Maiorano D.
Recolin B, van der Laan S, Tsanov N, Maiorano D.
Bétous R., Pillaire, M-J, Pierini, L., Van der Laan, S., Recolin B., Ohl-Séguy, E., Guo, C., Niimi, N., Gruz, P., Nohmi, T. Friedberg, E., Cazaux, C., Maiorano, D* and Hoffmann J-S*. * corresponding authors
Maiorano, D., Hoffmann, JS.
Van der Laan, S., Crozet, C., Tsanov, N., and Maiorano, D
Recolin, B., Maiorano, D
Recolin, B., Van der Laan, S., and Maiorano, D.
Levy N, Oehlmann M, Delalande F, Nasheuer HP, Van Dorsselaer A, Schreiber V, De Murcia G, Ménissier-de Murcia J, Maiorano D, Bresson Anne.
Recolin, B., Maiorano, D.
Auziol C, Mechali M, Maiorano D.
Maiorano D, Lutzmann M, Mechali M.
2006 - Curr Opin Cell Biol.
, 18, 130-136 16495042
Service porteur :
Replication and Genome Dynamics
Lutzmann M, Maiorano D, Mechali M.
2006 - EMBO J.
, 25(24):5764-74 17124498
Service porteur :
Replication and Genome Dynamics
Maiorano, D., Krasinska, L., Lutzmann, M. and Mechali M.
2005 - Current Biology
, 15, p 146-153
Service porteur :
Replication and Genome Dynamics
Maiorano, D., Cuvier, O., Danis, E., and Mechali, M.
2005 - Cell
, 120, 315-3128
Service porteur :
Replication and Genome Dynamics
Lutzmann, M., Maiorano, D., and Méchali, M.
2005 - Gene
, 362:51-6 16226853
Service porteur :
Replication and Genome Dynamics
Maiorano, D., Rul, W., and Marcel Mechali
2004 - Experimental Cell research
, 295, 138-149
Service porteur :
Replication and Genome Dynamics
Danis, E., Brodolin, K., Menut, S., Maiorano, D., Girard-Reydet, C. and Marcel Méchali.
2004 - Nature Cell Biology
, 6, 721-730. This article has been the subject of an Editors
Service porteur :
Replication and Genome Dynamics
Thepaut, M., Maiorano, D., Guichou, JF., Auge, MT., Dumas, C., Méchali, M., and Padilla, A.
2004 - J Mol Biol.
, 342, 275-287
Service porteur :
Replication and Genome Dynamics
Françon, P. ; Lemaitre, JM., Dreyer, C. ; Maiorano, D. ; Cuvier, O. and Marcel Méchali.
2004 - J Cell Science
, 117, p 4909-4920
Service porteur :
Replication and Genome Dynamics
Maiorano, D., and Méchali, M.
2002 - Nature Cell Biology
, 4, E58-E59
Service porteur :
Replication and Genome Dynamics
Tada, S., Li, A., Maiorano, D., Méchali, M., and Blow, J.
2001 - Nature Cell Biology
, 3, 107-113
Service porteur :
Replication and Genome Dynamics
Maiorano, D., Lemaître, J.M. and Méchali, M.
2000 - J. Biol. Chem.
, 275, 8426-8431
Service porteur :
Replication and Genome Dynamics
Maiorano, D., Moreau, J., and Méchali, M.
2000 - Nature
, 404, 622-625 ( cf also News and Views 404, 560-561)
Service porteur :
Replication and Genome Dynamics
Françon, P., Maiorano, D. and Méchali, M.
1999 - Minireview FEBS Letters
, 452, 87-91.
Service porteur :
Replication and Genome Dynamics
Coué, M., Amariglio, F., Maiorano, D., Bocquet, S. and Méchali, M.
1998 - Experimental Cell Research
, 245, 282-289.
Service porteur :
Replication and Genome Dynamics
It has been known for a longtime that the DDR is inefficient in the early embryos, however the reasons for this regulation and the underlying molecular bases are poorly understood. We have explored this issue in the early embryos of fruit fly Drosophila melanogaster, the clawed frog Xenopus laevis as well as in mouse embryonic stem cells (ES cells).
In Xenopus, we have discovered that the DDR is inefficient because the embryos efficiently by-pass DNA lesions by constitutive activation of the DNA damage tolerance pathway involving translesion DNA synthesis (TLS). This regulation limits replication fork stalling in front of DNA lesions and therefore DDR activation (Figure 1). We have explored the consequences of constitutive TLS activation on genome stability during embryonic development. We have observed a very high mutation rate as well as the presence of large DNA rearrangements that depend on TLS. We have also determined the consequences of such mutations throughout development in Drosophila. We have found that absence of the TLS DNA polymerase eta (Pol eta) during the earliest stages of embryonic development results in reduced viability at the larva stage, and in decreased genetic variability on pericentromeric heterochromatin in the adults. We also found that the mutagenic signature of TLS Pol eta identified in Drosophila is similar to that found in certain human cancers (Figure 2, Lo Furno et al., Nucleic Acids Research, in press). This constitutes a novel mechanism of genetic variation operating during very early development contributing to the individual genetic polymorphism and may explain the predisposition to develop cancer. These findings also pave the way to understand the molecular basis of genome instability observed in human embryos.
Figure 1. Constitutive activation of translesion DNA synthesis inhibts DDR activation during early Xenopus development. (Adapted from Kermi et al., Dev Cell 2015).
Figure 2. Upper panels, very early Drosophila and Xenopus embryos. Middle panel, embryonic mutational signature of TLS Pol eta. Lower panel, Heatmap showing the normalized relative contribution of TLS Pol eta mutational signatures from human tumors identified in COSMIC database.
Mouse embryonic stem cells (ES) also display an inefficient DDR for the G1/S checkpoint and by consequence show several signs of genomic instability. We have discovered that in these cells the G1/S checkpoint is inefficient because the critical G1/S regulator, the CDC25A protein phosphatase, is very abundant. We have also identifed the molecular bases of this abundance by showing that its stability depends upon the Dub3 ubiquitine hydrolase whose expression is under control of two pluripotency factors, Esrrb and Sox2 (van der Laan et al., 2013 Mol Cell and Figure 2). We are currently investigating the molecular basis of genomic instability of ES and iPS cells to improve their use in regenerative medicine.
Figure 3. Cartoon showing how Dub3 expression controls activation of the G1/S checkpoint and the pluripotent state of mouse ES cells.
We have shown that ectopic expression of Rad18 in human somatic cells is sufficient to constitutively activate translesion DNA synthesis and shut down the DDR, as observed in the early embryo (Figure 3). In these conditions cells shows acquired resistance to DNA damaging agents, including those currenlty used in the clinical, such as cisplatin. We have also observed a strong expression of Rad18 in cancer stem cells of the agressive brain tumor glioblastoma, a cancer that shows an extraordinary resistance to therapy. We are currently exploring the possiblity to use Rad18 as a novel target in the treatment of this cancer whose outcome is still very poor.
Figure 4. Ectopic Rad18 expression in somatic mammalian cells is sufficient to induce spontaneous translesion synthesis nuclear focus formation.
In the aim of identifying new DDR-responsive genes, we have developped an in vitro screen using protein extracts derived from Xenopus eggs and identified five genes candidates. One of these is the Ddx19 RNA helicase, previously implicated in the export of the mRNA from the nucleus into the cytoplasm. We have shown that Ddx19 translocates from the nuclear peryphery into the nucleus upon DNA damage (Figure 4). We have also unveiled a novel nuclear function for this enzyme in the resolution of aberrant RNA:DNA hybrid structures formed upon conflicts between replication and transcription, the so called R-loops (Hodroj et al., EMBO J 2017). We are now in the process of understanding the molecular basis of this novel function for the Ddx19 helicase.
Figure 5. Model showing the ATR-dependent Ddx19 function in nuclear R-loop resolution.
Subject: Molecular characterization of new factors involved in DNA damage tolerance
Hanane Mechri - Start October 2021 Supervisor: Domenico Maiorano Co-supervisor: Antoine Aze
Thesis proposal: Subject: Molecular characterization of new factors involved in DNA damage tolerance
Course and current status
Since April 2007. Group leader of the "Genome Surveillance and Stability" team at the Institute of Human Genetics of Montpellier (France). Biochemistry and Cell Biology of DNA damage and replication checkpoints.
2001. Staff researcher employed by INSERM at the CNRS Institute of Human Genetics of Montpellier (France).
1997-2001. Postdoctoral fellow at the Institute Jacques Monod (Paris, France), then at the Institute of Human Genetics of Montpellier (France). Biochemistry of DNA replication in Xenopus in vitro systems.
1996. Research Assistant at the University of Oxford.
1995. PhD at the University of Oxford (England, UK). Cell cycle regulation of DNA replication in fission yeast.
Membership