Research Group de Bruin

Faculty of Veterinary Medicine, Utrecht University, Dept. of Pathobiology
Contact: Prof. Alain de Bruin
E-mail: A.debruin@uu.nl

 E2F signalling in vascular development, tissue regeneration, and cancer

General research focus: We are interested in the molecular mechanism that control cell proliferation in normal cells and in cancer cells. We want to understand how E2F transcription factors mediate the appropriate control of the cell cycle entry and exit that is required for normal development and tumor suppression. We are addressing this question using mutant mouse and zebrafish models as well as cell culture models. Current research is focussed on the mechanism of E2F action controlling the cell cycle by identifying its specific regulators and by inactivating its function during vascular development, tissue regeneration and cancer. 

The E2F family of transcription factors plays a critical role in coordinating expression of many essential genes involved in cell proliferation, apoptosis and differentiation. Deregulation of E2F activity has been detected in the majority of cancers illustrating the importance of its activity for normal growth control.

A complete understanding of how E2F activity regulates gene expression is now in reach, because we recently identified the final two members of this family. We show that these two E2F members function in concert to repress gene expression and suppress killing activities of other family members, suggesting that their function is important for keeping the E2F family in balance. Moreover, we demonstrate that inactivation of these E2Fs results in severe vascular defects. While the molecular mechanism is unknown, E2Fs appear to orchestrate blood vessel formation; a process that is critical for tissue renewal and tumor growth. 

We have developed vessel formation assays in zebrafish allowing real-time mechanistic studies in vivo that were previously only feasible in vitro. In addition, we will take advantage of our novel cancer model in mice which is induced by tissue repair. Combined with our unique gene targeting tools, this puts us in a strong position to elucidate whether specific E2Fs are essential for vascular development, tissue regeneration and tumorigenesis and dissect their mechanism of action. Furthermore we want to understand the molecular wiring of E2F regulation using a proteomic approach identifying factors that directly interact with E2Fs or control its expression.

Techniques: Chromatin immunoprecipitation assays, co-immunoprecipitation assays, Western blots, real-time PCR, si-RNA technology, site-directed and deletion mutagenesis assays, molecular cloning, cell culture/ transfection, Luciferase-reporter assays, real-time confocal immunofluoresence imaging, partial hepatectomy regeneration model, cell type specific Cre-loxP deletion, in-situ hybridization, immunohistochemistry, morpholino technology

The research group is composed of postdocs (5), PhD-students (2), technicians (4), board-certified veterinary pathologists (2), excellent-trace veterinary students (2), master student (1), HLO-student (1), supporting staff (1) 

Relevant publications:

J. Li, C. Ran, E. Li, F. Gordon, G. Comstock, H. Siddiqui, W. Cleghorn, H. Chen, K. Kornacker, S. Pandit, M. Khanizadeh, M. Weinstein, G. Leone, and A. de Bruin. Synergistic Function of E2F7 and E2F8 is Essential for Cell Survival and Embryonic Development. Developmental Cell 2008 Jan; 14(1):62-75.

S. Tsai, R. Opavsky, N. Sharma, L. Wu, S. Naidu, E. Nolan, E. Feria-Arias, C. Timmers, J. Opavska, A. de Bruin, J. Chong, P. Trikha, S. Fernandez, P. Stromberg, TJ. Rosol and G. Leone. Mouse Development with a Single E2F Activator. Nature 2008 Aug 28; 454(7208): 1137-41

PL.  Wenzel*, L. Wu*, A. de Bruin, J. Chong, W. Chen, G. Dureska, E. Sites, T. Pan, A. Sharma, K. Huang, R. Ridgway, K. Mosaliganti, R. Sharp, R. Machiraju, J. Saltz, H. Yamamoto, JC. Cross, ML. Robinson, G. Leone. Rb is critical in a mammalian tissue stem cell population. Genes and Development 2007 21, 85-97. *Equal contribution

B. Maiti, J. Li, A. de Bruin, F. Gordon, C. Timmers, R. Opavsky, K. Patil, J. Tuttle, W. Cleghorn, G. Leone. Cloning and characterization of mouse E2F8, a novel mammalian E2F family member capable of blocking cellular proliferation. Journal of Biological Chemistry, 2005, Feb 18; 280(18):18211-20.

A. de Bruin, B. Maiti, L. Jakoi, C. Timmers, R. Buerki, and G. Leone. Identification and characterization of E2F7, a novel mammalian E2F family member capable of blocking cellular proliferation. Journal of Biological Chemistry, 2003, Oct. 24; 278(43): 42041-42049.

A. de Bruin, L. Wu, H. I. Saavedra, P. Wilson, Y. Yang,  T. J. Rosol, M. Weinstein, M. L. Robinson, and G. Leone. Rb-function in extraembryonic lineages suppresses apoptosis in the central nervous system in Rb-deficient mice. Proc.Natl. Acad. Sci..USA, 2003, May 27; 100(11): 6546-6551.

L. Wu, A. de Bruin, H. I. Saavedra, A. Trimboli, Y. Yang, J. Opavska, P. Wilson, M. Starovic, M. C. Ostrowski, J. C. Cross, M. Weinstein, T. J. Rosol, M. L. Robinson, and G. Leone. Extraembryonic Function of Rb Is Essential for Embryonic Development and Viability. Nature 2003, Feb. 27; 421(6921): 942-7.