Boston University Department of Biology

Faculty Profiles

Current Research

Regulating gene expression in mammalian cells controls biological processes such as cell growth and responses to hormones. Our interests span how regulation of transcription factors activates or represses expression of critical genes, and how signal transduction pathways target transcription machinery, in order ultimately to control cell growth in response to mitogenic factors and to protect blood vessels from injury and cardiovascular disease by estrogen. We also use bioinformatics to understand transcriptional regulatory networks involved in these biological processes.

The transcription factor LSF, one major focus, controls cell growth and cell cycle progression into DNA replication. A critical gene targeted by LSF is thymidylate synthase, an essential enzyme for cell growth that many cancer chemotherapeutic drugs specifically inhibit. LSF activity is regulated by phosphorylation at a number of sites, in response to multiple signaling pathways. Its activity is tightly regulated during cell growth stimulation and cell cycle progression.

A second major focus is how estrogen protects against cardiovascular disease. Cells respond to estrogen through two estrogen receptors, which recognize specific sequences in DNA and regulate transcription of the associated genes. We are identifying transcriptional targets of these estrogen receptors in vascular endothelial and vascular smooth muscle cells, with the goal of determining which are critical to control cell proliferation and migration. These studies aim to establish a benchmark for cellular genes that may be targeted for pharmaceutical intervention in treatment or prevention of cardiovascular disease.

Courses Taught

• BI 753 Advanced Molecular Biology
• BI 203 Cell Biology

Selected Publications

• Hansen U, Owens L, Saxena UH (2009). Transcription factors LSF and E2Fs: Tandem cyclists driving G0 to S? Cell Cycle, 8:2146-2151.
• Saxena UH, Powell CMH, Fecko JK, Cacioppo R, Chou HS, Cooper GM, Hansen U. (2009). Phosphorylation by cyclin C/CDK2 following mitogenic stimulation of murine fibroblasts inhibits transcriptional activity of LSF during G1 progression. Molecular and Cellular Biology 29, 2335-2345.
• Repetny KJ, Zhou X, Holodick NE, Rothstein TL, Hansen U. (2009). Binding of LBP-1a to specific immunoglobulin switch regions in vivo correlates with specific repression of class switch recombination. European Journal of Immunology, 39:1387-1394.
• Zhu N, Hansen U. (2007). HMGN1 modulates estrogen-mediated transcriptional activation through interactions with specific DNA-binding transcription factors. Mol Cell Biol 27, 8859-8873.
• O’Lone R, Knorr K, Jaffe IZ, Schaffer ME, Martini PGV, Karas RH, Bienkowska J, Mendelsohn ME, Hansen U. (2007). Estrogen receptors alpha and beta mediate distinct pathways of vascular gene expression, including genes involved in mitochondrial electron transport and generation of reactive oxygen species. Mol Endocrinol. 21, 1281-1296.
• Frith MC, Fu Y, Yu L, Chen J-F, Hansen U, Weng Z. (2004). Detection of functional DNA motifs via statistical overrepresentation. Nucleic Acids Res. 32, 1372-1381.
• Ding H-F, Rimsky S, Batson SC, Bustin M, Hansen U. (1994). Stimulation of RNA polymerase II elongation by chromosomal protein HMG-14. Science 265, 796-799.
• Licht JD, Grossel MJ, Figge J, Hansen U. (1990). Drosophila Krüppel protein is a transcriptional repressor. Nature 346, 76-79.