A functional link between the MRN complex and the Gcn2p kinase uncovered by the antitumour drug beta-lapachone

JOSÉ RAMÓN MURGUÍA; MAURICIO ARIEL MENACHO; PÉREZ-VALLE, J; GADEA, J; ARIÑO, J

Lyon

Congreso; 20th Meeting of the European Association for Cancer Research; 2008

European Association for Cancer Research (EACR)

Background: Beta-lapachone (b-lap) is an anticancer agent that selectively induces cell death in several human cancer cells. We previously reported that, in budding yeast, b-lap was cytotoxic, induced DNA damage and activated a G1/S Mre11-Tel1p checkpoint pathway preceding death. Our aim was to gain further insights into the mechanism of b-lap action and identify the molecular targets of b-lap action. Materials and methods: We compared the gene expression profile of the b-lap treated yeast cells with that obtained from untreated cells using cDNA microarrays. We used Significance Analysis of Microarrays to identify differentially expressed genes between untreated/b-lap treated cells. The data obtained after analysis of the microarray was validated by standard yeast genetics and molecular biology approaches. Results: Interestingly, numerous amino acid biosynthesis genes were found to be regulated by the drug, suggesting that b-lap might activate the General Control of Nutrients (GCN) pathway in yeast. Accordingly, b-lap treatment incremented phosphorylation of the eIF2 alpha subunit in a GCN1, GCN2 and GCN20-dependent manner. Suriprisingly, phsophory- lation of eIF2alpha was fully dependent on the MRN complex. Furthermore, Gcn2p kinase modulated i) checkpoint responses triggered by b-lap treatment, and ii) cell viability in response to b-lap exposure. finally, we found that Gcn2p regulated checkpoint function by mechanisms other than eIF2α phosphorylation. Conclusions: These data uncover a functional link between the Gcn2p kinase and the MRN complex and suggest that Gcn2p may have additional functions besides regulating translation.