Emily Humphrey Dixon Assistant Professor, Biochemistry Johnson Hall of Science, Room 226 (315) 229-5671 email: edixon@stlawu.edu B.A. Middlebury College, Biochemistry (2000) Ph.D. Harvard University (2005) Postdoctoral Fellow, Broad Institute of Harvard and MIT, 2005-2006

Currently Teaching the Following Courses

Fall 2009
Chemistry 309A-Intro to Biochemistry (dual-listed as Biochemistry 309A)
Biochem 107 - The Science of Food)
Biochem 395 - Research Methods in Molecular Biochemistry
Biochem 489 - Senior Year Experience (Projects)

Spring 2009
Biology 394 - Biochemistry Research Methods
Chemistry 490 - Senior Research

RESEARCH INTERESTS:

• Gene regulation: activation and repression of genes by acetylation and deactylation of lysine residues on histone proteins.
• Molecular mechanisms by which organisms repond to nutrient limitation (e.g., rapamycin - read more)
• Molecular mechanisms that lead to altered gene regulation following nutrient limitation

Research Statement

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 diseases 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.  I am also currently examining other regulatory mechanisms that work in concert with deacetylation by Rpd3p.

Selected Publications: