Dr. Emily Dixon Assistant Professor of Biology and Chemistry Office: Johnson Hall of Science Room 226 Phone: 315-229-5671, fax:315-229-7429 email: edixon@stlawu.edu

Education:

2005-2006 Postdoctoral Fellow, Broad Institute of Harvard and MIT, Cambridge, MA

Ph.D. 2005 in Biochemistry from the Department of Molecular and Cellular Biology at Harvard University, Cambridge, MA

B.A. 2000 in Biochemistry from Middlebury College, Middlebury, VT

Courses Offered:

Introduction to Biochemistry
Advanced Biochemistry
Research Methods in Molecular Biology
Research Methods in Biochemistry

Research Interests:

I am interested in understanding how genes are regulated.  All of our cells have the same genes, but our liver cells are different from our heart cells which are different from our skin cells.  The difference is in which genes are turned on and which genes are turned off.  Organisms are also able to adapt to changing environmental conditions by altering gene regulation, and several genes are known to result from the misregulation of genes.

I am also interested in the molecular mechanisms by which organisms respond to nutrient limitation.  Part of this response has been well-characterized, but there is still a lot to learn.  A small molecule called Rapamycin has been identified that inhibits the nutrient-sensing pathway and so makes cells “think” that they are starving.  Treating cells with rapamycin leads to many responses favoring the reuse of nutrients (for example, breaking down non-essential proteins to reuse the amino acids).  It also leads to a rapid and dramatic change in gene regulation.

I have combined these interests by studying the molecular mechanisms that lead to altered gene regulation following nutrient limitation.  The yeast Saccharomyces cerevisiae is a single-celled eukaryote.  This yeast has similar mechanisms for regulating gene expression to those used by humans, but they are much simpler.  Yeast are also easy to grow, have a short generation time, and can be easily genetically manipulated.

One way that both yeast and humans regulate gene expression is by acetylating and deacetylating lysine residues on histone proteins (the proteins that DNA is wrapped around in eukaryotic cells).  The acetyl groups are attached by histone acetyltransferases (HATs) and taken off by histone deacetylases (HDACs).  I have identified a yeast HDAC, Rpd3p, that is required for both the activation and repression of many genes.  I have shown that Rpd3p becomes bound to the promoters of many genes following treatment with rapamycin.

My current research focuses on understanding, at the molecular level, how Rpd3p becomes bound to these gene promoters following rapamycin treatment.

Selected Publications:

Bernstein BE, Liu CL, Humphrey EL, Perlstein EO and Schreiber SL.  Global nucleosome occupancy in yeast.  Genome Biol. 2004; 5(9):R62.

Humphrey EL, Shamji AF, Bernstein BE and Schreiber SL.  Rpd3p relocation mediates a transcriptional response to rapamycin in yeast.  Chem Biol.  2004; 11(3):295-9.

Bernstein BE, Humphrey EL, Liu CL and Schreiber SL. The use of chromatin immunoprecipitation assays in genome-wide analyses of histone modifications.  Methods Enzymol. 2004; 376:349-60.

Bernstein BE, Humphrey EL, Erlich RL, Schneider R, Bouman P, Liu JS, Kouzarides T, Schreiber SL.  Methylation of histone H3 Lys 4 in coding regions of active genes.  Proc Natl Acad Sci USA.  2002; 99(13):8695-700.