Abstract 3038: G quadruplex stabilization induces mitophagy in S. cerevisiae

Abstract

Abstract G-quadruplex (G4) DNA structures are stable planar structures held together by multiple G-G base pairs. G4 structures are thought to affect transcription and other chromosomal processes but their presence in vivo is also expected to slow replication fork progression. Previous work from our lab demonstrates that the S. cerevisiae Pif1 5′ to 3′ DNA helicase is a particularly potent unwinder of G4 structures in vitro1. In addition, cells lacking the Pif1 helicase exhibit replication fork slowing and DNA breakage at G4 motifs, chromosomal sequences that form intra-molecular G4 structures in vitro1,2. In addition, treating yeast in vivo with the G4 stabilizing drug PhenDC3 increases G4-mediated genome instability3. We treated a collection of 4,783 S. cerevisiae strains that each contained a single gene deletion with PhenDC3 to search for genes that are sensitive or resistant to PhenDC3. We will discuss results showing that several yeast genes that affect maintenance of mitochondrial DNA and autophagy induction are hypersensitive to PhenDC3. Using fluorescent microscopy and immunoblotting, we further demonstrate that treatment of wild type S. cerevisiae cells with PhenDC3 induces autophagy, and more specifically, mitophagy. Moreover, cells lacking Pif1 are themselves activated for autophagy. Reference: 1 Paeschke, K. et al. Pif1 family helicases suppress genome instability at G-quadruplex motifs. Nature 497, 458-+, doi:10.1038/nature12149 (2013). 2 Paeschke, K., Capra, J. A. & Zakian, V. A. DNA replication through G-quadruplex motifs is promoted by the Saccharomyces cerevisiae Pif1 DNA helicase. Cell 145, 678-691, doi:10.1016/j.cell.2011.04.015 (2011). 3 Piazza, A. et al. Genetic instability triggered by G-quadruplex interacting Phen-DC compounds in Saccharomyces cerevisiae. Nucleic Acids Res 38, 4337-4348, doi:10.1093/nar/gkq136 (2010). Citation Format: Jennifer Stundon. G quadruplex stabilization induces mitophagy in S. cerevisiae. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3038. doi:10.1158/1538-7445.AM2015-3038