... / ... / Research / Non-Homologous End-Joining

Non-Homologous End-Joining

Group leader: Dik van Gent

Group members (from left to right): Nicole Verkaik, Anja Raams, Dik van Gent,
Inger Brandsma, Koos Jaspers and in the front Ricardo Leite and Kishan Naipal

The group studies various aspects of DNA double strand break repair, with an emphasis on the non-homologous end-joining (NHEJ) pathway and implications of repair deficiencies for disease and (cancer) therapy. We address the complexity of DNA double strand break repair at the levels of biochemistry, cell biology, genetics, patient materials and animal models. In collaboration with the Department of Immunology (Prof. Jacques van Dongen and Dr. Mirjam van der Burg) we investigate NHEJ defects in Severe Combined Immunodeficiency patients. In collaboration with various clinical departments we study DNA repair defects in tumours.

Accumulation of NHEJ factors on laser–induced DNA damage

In addition to investigating the end-joining mechanism, we are also interested in the crosstalk within the DNA damage response. We are especially interested in factors that influence the choice of double strand break repair pathway (non-homologous end-joining or homologous recombination) and the interplay with other processes in the DNA damage response, such as cell cycle checkpoints and apoptosis induction. We study this both in the context of cells in culture and in tissues and tumours.

Specific research projects:

1. Mechanism of NHEJ
We investigate the composition and function of NHEJ complexes assembled on DNA ends. At this moment we study this subject primarily using purified proteins. We are especially interested in the dynamics of assembly and disassembly of NHEJ complexes and how various events, such as DNA-PK autophosphorylation, influence these dynamics. The ultimate goal is to understand all factors involved in complex assembly and function and to extrapolate the in vitro results to the in vivo situation, using live cell microscopy techniques.


2. Crosstalk between NHEJ and other elements of the DNA damage response (Ricardo Leite, Nicole Verkaik)

We investigate how NHEJ interacts with other DNA damage response pathways to counteract the negative consequences of DNA double strand breaks (e.g. after gamma-irradiation). We are currently mainly interested in the role of microRNA responses in regulating various elements of the DNA damage response after ionizing radiation, as well as gene regulation after low dose radiation. We found several pathways that show gene expression regulation after low or high dose ionizing radiation and are currently investigating the role of several genes in the DNA damage response.


3. NHEJ defects and SCID (in collaboration with Hanna IJspeert and Mirjam van der Burg, Immunology)

We investigate the genetic defects in Severe Combined Immunodeficiency (SCID) patients, especially in radiosensitive patients. We have identified and characterized defects in the Artemis, ligase IV, DNA-PKcs and Xlf/Cernunnos genes. We are committed to solve the underlying defect in these patients in molecular detail, including understanding of the molecular mechanisms leading to the patient phenotype caused by non-null mutations in these genes.


4. DNA damage responses in tissues and tumours (in collaboration with Agnes Jager (Internal Oncology), Carolien van Deurzen (Pathology), Joost Boormans (Urology) and Arno van Leenders (Pathology))

We study DNA damage responses in cells within tissues and tumours. In collaboration with the Departments of Internal Oncology and Pathology we develop novel techniques to study DNA repair, cell cycle checkpoint activation and apoptosis in living breast and ovarian tumour slices, with the ultimate goal to develop methods to predict treatment response in the tumour. The primary focus is at this moment on tumour sensitivity to PARP inhibitors, which are in clinical trials for hereditary breast and ovarian cancer, but may also be useful for treatment of sporadic tumours.
In collaboration with the Departments of Urology and Pathology, we are developing similar DNA damage response assays for bladder and prostate cancer. Again, the primary goal is to develop assays that have predictive value for therapy response.




Contact information:
Dr. Dik C. van Gent
Dept. of Genetics
Erasmus MC
PO Box 2040
3000 CA Rotterdam
The Netherlands
Tel. +31-10-7043932
FAX: +31-10-7044743
e-mail: d.vangent@erasmusmc.nl


Some recent publications:

van Gent, D.C., Hoeijmakers, J.H.J., and Kanaar, R. (2001). Chromosomal stability and the DNA double-stranded break connection. Nat. Rev. Genet., 2, 196-206.
  • Mari, P.O., Florea, B.I., Persengiev, S.P., Verkaik, N.S., BrĂĽggenwirth, H.T., Modesti, M.M., Giglia-Mari, G., Bezstarosti, K., Demmers, J.A.A., Luider, T.M., Houtsmuller, A.B. and van Gent, D.C. (2006) Dynamic Assembly of End-joining Complexes Requires Interaction between Ku70/80 and XRCC4. Proc. Natl. Acad. Sci. USA, 103, 18597-18602.
  • Van Gent, D.C. and van der Burg, M. (2007) Non-Homologous End-Joining, a Sticky Affair. Oncogene, 26, 7731-7740.
  • Van der Burg, M., IJspeert, H., Verkaik, N.S., Turul, T., Wiegant, W.W., Morotomi-Yano, K., Mari, P.O., Tezcan, I., Chen, D.J., Zdzienicka, M.Z., van Dongen, J.J.M. and van Gent, D.C. (2009) DNA-PKcs Mutation In a T-B-SCID Patient Inhibits Artemis Activation and Non-Homologous End-Joining. J. Clin. Invest., 119, 91-98.
  • Weterings, E., Verkaik, N.S., Keijzers, G., Florea, B.I., Wang, S.Y., Ortega, L.G., Uematsu, N., Chen, D.J. and van Gent, D.C. (2009) The Ku80 carboxy-terminus stimulates Joining and Artemis-mediated processing of DNA ends. Mol. Cell. Biol., 29, 1134-1142.
  • Pothof, J., Verkaik, N.S., Hoeijmakers, J.H.J. and van Gent, D.C. (2009) MicroRNA responses and stress granule formation modulate the DNA damage response. Cell Cycle, 8, 3462-3468.
  • Brugmans, L., Verkaik, N.S., Kunen, M., van Drunen, E., Williams, B.R., Petrini, J.H., Kanaar, R., Essers, J. and van Gent, D.C. (2009) NBS1 cooperates with homologous recombination to counteract chromosome breakage during replication. DNA Repair, 8, 1363-1370.