Florencia Lopez


Saccharomyces cerevisiae is a unicellular microorganism, a species of budding yeast, which has been extensively used in brewing beer and baking bread. Recently it has become one of the main eukaryotic model systems used in cellular and molecular biology. The picture is an artistically modified version of yeast cells expressing Puf3p-GFP grown under different carbon sources. Puf3p-GFP is a fusion construct between our protein of interest (Puf3p) and a fluorescent molecule (GFP) to allow visualization of Puf3p localization and/or activity in response to changes in carbon source. Analyzing changes in Puf3p activity will broaden our knowledge of gene expression regulation.

Proper regulation of gene expression at a cellular level is required in all organisms for their successful adaptation and survival to physiological or environmental changes. In eukaryotes, an efficient way of modulating gene expression is achieved by adjusting the decay rates of different mRNAs and thus, protein levels.  Failure in proper regulation can cause stabilization of certain mRNAs resulting in abnormal protein levels that render pathological patterns as observed in cancer cells. Therefore, understanding gene expression regulation is opening a new horizon to cancer therapy.

Our research focuses on the eukaryotic Puf family of proteins in yeast. These RNA-binding proteins regulate the lifespans of target mRNAs by sequence specifically binding to them and modulating their decay rates. I have studied Puf3p’s mechanism of action in mRNA decay regulation. Specifically, I have found that physiological conditions play a key role in regulation of Puf3p activity. While Puf3p was inactivated by ethanol, galactose and raffinose, Puf3 protein levels were not decreased compared to a glucose control, but Puf3p-GFP in the former conditions was differently distributed than in glucose, which correlated to a change in the protein’s activity. Given the structural and functional similarities between Puf proteins within eukaryotes, it is very likely that our findings might be useful for further understanding regulation of gene expression in mammals, contributing to the new developing medical field in gene therapy.


Portraits Of Research 2009