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Ellen Li, M.D., Ph.D.
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Ellen Li, M.D., Ph.D. Professor of Medicine Office Location: CSRB-North Tower Room 927 Dr. Li joined the Gastroenterology Division in 1986. She received her M.D. and Ph.D. degrees from Washington University School of Medicine. She completed her internal medicine training at Massachusetts General Hospital and returned to Washington University for a fellowship in gastroenterology. The major focus of Dr. Li's current research is on the structure and function of intestinal vitamin A binding proteins. A second focus of her research is on the pathogenesis of amebiasis. Research Interests The major focus of our work is to understand the structure and function of vitamin A binding proteins. We have examined the structure and function of an abundant intestinal binding protein, cellular retinol binding protein II (CRBP II). Using high-resolution multidimensional nuclear magnetic resonance analysis, we have detected changes in conformation between the liganded and unliganded forms of CRBP II, that were not observed in the crystalline forms. Analysis of CRBP II knockout mice generated in this laboratory reveal that this protein plays a critical role in the prenatal transfer of maternal vitamin A to the developing fetus when dietary maternal vitamin A is limiting. More recently, the laboratory has begun studying the NMR structure and dynamics of the nuclear hormone receptor, retinoid-x-receptor a (RXRa). RXRa is a member of the nuclear hormone receptor family and consists of a DNA binding domain and a ligand-binding domain (LBD). While it is capable of binding to cis-acting DNA elements as homodimers, it also serves as an obligate heterodimeric partner for multiple other nuclear hormone receptors involved in lipid nutrient signaling, including the peroxisomal proliferator-activated receptors and the vitamin D receptor. These receptors potentially play an important role in colonic mucosal proliferation. RXRa binds 9-cis retinoic acid and docosahexaenoic acid. Upon binding ligand, the LBD undergoes conformational changes that leads to altered recruitment of corepressors and coactivators, that in turn results in altered transcriptional regulation of target genes. We have made sequence specific resonance assignments for the liganded and unliganded forms of the RXRa LBD. This will allow us to study the interactions of the RXRa LBD with ligands, coactivator peptides and the ligand binding domains of other nuclear receptors. My clinical interests include GI infections and IBD.
Link to Medline for selected publications
Division of Gastroenterology
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