JULIE LESSARD, Ph.D.
AWARDS & HONOURS
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Recipient of Canada's Top 40 Under 40 Award, 2009
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Career Development Award, Human Frontier Science Program, 2008-
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Canada Research Chair in Molecular Genetics of Stem Cells
Hematopoiesis, 2007-
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Human Frontier Science Program Postdoctoral Fellow, HFSP Organization, 2004-2007
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Dean’s Honor List for Doctoral Thesis, Université de Montréal, 2003
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Berlex Canada Award for Excellence in Hematology-Oncology, 2002
TRAINING
- Postdoctoral training with Gerald R. Crabtree, Stanford University, Palo Alto, 2003-2007
- Ph.D. in Molecular Biology with Guy Sauvageau, Clinical Research Institute of Montreal, Université de Montréal, 1996-2003
RESEARCH SUPPORT
- Canada Foundation for Innovation
- Canadian Cancer Society Research Institute
- Canadian Institutes of Health Research
Julie Lessard is a principal investigator at the Institute for Research in Immunology and Cancer and holds the Canada Research Chair in Molecular Genetics of Stem Cells
Hematopoiesis. She is an assistant professor in the Department of Pathology and Cell Biology at the Université de Montréal.
When Julie Lessard began her doctoral studies at the Clinical Research Institute of Montreal in 1997, she chose to investigate the role of a family of epigenetic regulators of the chromatin structure, the Polycomb Group (PcG) genes, in normal and leukemic hemopoiesis. Her studies established that the PcG gene Bmi-1 is a key genetic determinant of the self-renewal capacity of both embryonic and adult hemopoietic stem cells (HSCs). Most importantly, her work also showed that this function of Bmi-1 is preserved in leukemic stem cells (L-HSCs), providing the first molecular basis for the concept that stem cell function (whether normal or neoplastic) is regulated by common regulatory genes. These exciting findings lend strong support to the idea that the initial cancer-causing (transforming) mutations occur in normal hemopoietic stem cells, causing them to start dividing in an aberrant manner. Moreover, they reinforced the notion of a structure in the leukemic hierarchy, where Bmi-1 defines “stemness”.
Dr. Lessard did her postdoctoral training at Stanford University in California. She was awarded the prestigious Human Frontier Science Program Fellowship to accomplish this stage of her career (2004-2007). Her work led to the discovery of a novel epigenetic regulatory mechanism of mammalian neural development. Using proteomics approaches, she found that subunit exchange within neural, ATP-dependent SWI/SNF-like BAF chromatin remodeling complexes is essential for the transition from proliferating neural stem/progenitors to post-mitotic differentiated neurons. Most compellingly, she showed that self-renewal and proliferative activities of neural stem/progenitor cells require a specialized npBAF complex containing the double-PHD domain BAF45a subunit and the actin-related protein (Arp) BAF53a, assembled on the Brg/Brm ATPases. The dynamic exchange of these progenitor-specific subunits for the homologous BAF45b, BAF45c and BAF53b subunits during neural development is essential for cell cycle withdrawal and the acquisition of neuronal properties.
Dr. Lessard returned from abroad in 2007 to begin work as a principal investigator at IRIC. Using modern proteomics and molecular genetics approaches, the goal of her research is to provide a molecular understanding of the role of SWI/SNF-like BAF chromatin remodeling complexes in the generation, self-renewal, proliferation and differentiation of normal and leukemic stem cells.
SELECTED PUBLICATIONS
Wu JI*, Lessard J*, Olave IA, Qiu Z, Ghosh A, Graef IA, Crabtree GR (2007) Regulation of dendritic development by neuron-specific chromatin remodeling complexes. Neuron 56:94-108 * co-first authors
Sauvageau M, Miller M, Lemieux S, Lessard J, Hébert J, Sauvageau G (2007) Quantitative expression profiling guided by common retroviral insertion sites reveals novel and cell type-specific cancer genes in leukemia. Blood 111:790-799
Lessard J*, Wu JI*, Ranish JA, Wan M, Winslow MM, Staahl BT, Wu H, Aebersold R, Graef IA, Crabtree GR (2007) An Essential Switch in Subunit Composition of a Chromatin Remodeling Complex during Neural Development. Neuron 55:201-215 * co-first authors
Chagraoui J, Niessen SL, Lessard J, Girard S, Coulombe P, Sauvageau M, Meloche S, Sauvageau G (2006) E4F1: a novel candidate factor for mediating BMI1 function in primitive hematopoietic cells. Genes Dev 20:2110-2120
Lessard J, Faubert A, Sauvageau G (2004) Genetic programs regulating HSC specification, maintenance and expansion. Oncogene 23:7199-7209
Faubert A, Lessard J, Sauvageau G (2004) Are genetic determinants of asymmetric stem cell division active in hematopoietic stem cells? Oncogene 23:7247-7255
Lessard J and Sauvageau G (2003) Bmi-1 determines the proliferative capacity of normal and leukaemic stem cells. Nature 423:255-260
Lessard J and Sauvageau G (2003) Polycomb group genes as epigenetic regulators of normal and leukemic hemopoiesis. Exp Hematol 31:567-585
Lessard J, Schumacher A, Thorsteinsdottir U, van Lohuizen M, Magnuson T, Sauvageau G (1999) Functional antagonism of the Polycomb-Group genes eed and Bmi1 in hemopoietic cell proliferation. Genes Dev 13:2691-2703
Lessard J, Baban S, Sauvageau G (1998) Stage-specific expression of polycomb group genes in human bone marrow cells. Blood 91:1216-1224
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