PgmNr Y3143: Investigating the effects of gene overexpression on genome stability in Saccharomyces cerevisiae.

Authors:
Krystal Laframboise; Grant W. Brown


Institutes
Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada.


Keyword: Genomics

Abstract:

Accurate replication of the genome is essential for survival. The combination of both exogenous and endogenous sources of replication stress and DNA damage serve as a constant threat to the fidelity of this process. Fortunately, eukaryotic cells have a highly conserved DNA damage and replication checkpoint, which acts to recognize and repair damage to prevent genome instability. Though the mechanisms of genome maintenance have been extensively studied in Saccharomyces cerevisiae, almost all previous screens used to identify novel genes involved in these processes have employed loss-of-function alleles, subsequently ignoring the consequences of gene overexpression. These consequences are of particular interest as several disease states are associated with gene overexpression or gain-of-function mutations, including many human cancers. Here, we assay expression of the DNA damage-inducible gene, RNR3, using reporter synthetic genetic array methodology to identify genes causing genome instability when overexpressed. We find 41 of ~5100 genes screened result in increased RNR3 expression, including known DNA repair genes and transcriptional regulators of RNR3, confirming the capability of our screen to robustly identify genes of functional relevance. 58.5% of genes inducing RNR3 in our screen had no reported connection to genome stability when compared to previous overexpression studies, leaving 24 novel, putative genome maintenance genes for follow-up. We are currently using fluorescence microscopy to visualize the formation of various DNA damage-specific foci to ensure the mechanism of RNR3 induction caused by these novel candidates is related to genome instability and is not the result of transcriptional regulation. Furthermore, since 17 of our candidates have human homologues, our data will not only provide insight into novel pathways involved in genome maintenance in S. cerevisiae, but may also reveal novel pathways promoting oncogenesis in humans.



Yeast Database Genetic Index
1. gene symbol: RNR3; systematic name: YIL066C