Research Interests

Stem cells are of intense interest due to their potential use in regenerative medicine, their roles in many aspects of development, the continuous turnover of specific tissues, and their possible role in cancer. Stem cells have almost limitless proliferation capacity allowing a pool of cells to be available over long periods of time. However, some daughter cells must discontinue proliferation and enter a terminal differentiation pathway in order to form the required tissue. In order for stem cells to function properly, a balance must be maintained between proliferation and differentiation. In my lab we are studying how the balance between stem cell self-renewal (proliferation) and differentiation is regulated using the C. elegans germ line as a model. We are using genetic, molecular and biochemical techniques to identify the factors involved in regulating the proliferation versus differentiation decision and to determine how these factors are controlled.

Courses Taught

Graduate Students

Awards

2007 - Alberta Heritage Foundation Scholar Award
2005 - Canadian Foundation for Innovation New Opportunities Award

Selected publications

• Wang, X, Zhao, Y., Wong, K., Ehlers, P., Kohara, Y., Jones, S., Marra, M., Holt, R., Moermann, D. and Hansen, D. (2009) Identification of genes expressed in the hermaphrodite germ line of C. elegans using SAGE. BMC Genomics 10:213
• Mantina, P., MacDonald, L., Kulaga, A., Zhao, L. and Hansen, D. (2009) A mutation in teg-4, which encodes a protein homologous to the SAP130 pre-mRNA splicing factor, disrupts the balance between proliferation and differentiation in the C. elegans germ line. Mechanisms of Development 126:417-429
• MacDonald, L. D., Knox, A. and Hansen, D. (2008) Proteasomal regulation of the proliferation vs. meiotic entry decision in the C. elegans germ line. Genetics 180:905-920.
• Hansen, D. and Schedl, T. (2006) The regulatory network controlling the proliferation-meiotic entry decision in the Caenorhabditis germ line. Current Topics in Developmental Biology 76:186-215.
• Hansen, D., Hubbard, E. J. A. and Schedl, T. (2004) Multi-pathway control of the proliferation versus meiotic development decision in the C. elegans germ line. Developmental Biology 268:342-357.
• Hansen, D., Wilson-Berry, L., Dang, T. and Schedl, T. (2004) Control of the proliferation versus meiotic development decision in the C. elegans germ line through regulation of GLD-1 protein accumulation. Development 131:93-104.
• Maine, E. M., Hansen, D., Springer, D. and Vought, V. (2004) Caenorhbditis elegans atx-2 promotes germline proliferation and the oocyte fate. Genetics (in press)
• Stothard, P., Hansen, D., Pilgrim, D. (2002) Evolution of the PP2C Family in Caenorhabditis: Rapid Divergence of the Sex-Determining Protein FEM-2. J Mol Evol. 54(2):267-82.
• Hansen, D. and Pilgrim, D. (1999) Sex and the Single Worm: Sex Determination in the Nematode C. elegans. Mech. Dev. 83:3-15
• Cikaluk, D., Tahbaz, N., Hendricks, L. C., DiMattia, G.E., Hansen, D.,Pilgrim, D. and Hobman, T. C. (1999) Characterization of GERp95, a Membrane-Associated Protein that Belongs to a Family of Proteins Involved in Stem Cell Differentiation. Mol. Biol. Cell 10:3357-3372
• Hansen, D. and Pilgrim D. (1998) Molecular Evolution of a Sex Determination Protein: FEM-2 (PP2C) in Caenorhabditis. Genetics 149:1353-1362
• Pilgrim, D., McGregor, A., Jäckle, P., Johnson, T. and Hansen, D. (1995) The C. elegans Sex-Determining Gene fem-2 Encodes a Putative Protein Phosphatase. Mol. Biol. Cell 6:1159- 1171.