Overexpression of Autophagy-Related Genes Inhibits Yeast Filamentous Growth

Department of Molecular, Cellular and Developmental Biology and Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109-2216, USA.
Autophagy (Impact Factor: 11.75). 11/2007; 3(6):604-9. DOI: 10.4161/auto.4784
Source: PubMed


Under conditions of nitrogen stress, the budding yeast S. cerevisiae initiates a cellular response involving the activation of autophagy, an intracellular catabolic process for the degradation and recycling of proteins and organelles. In certain strains of yeast, nitrogen stress also drives a striking developmental transition to a filamentous form of growth, in which cells remain physically connected after cytokinesis. We recently identified an interrelationship between these processes, with the inhibition of autophagy resulting in exaggerated filamentous growth. Our results suggest a model wherein autophagy mitigates nutrient stress, and filamentous growth is responsive to the degree of this stress. Here, we extended these studies to encompass a phenotypic analysis of filamentous growth upon overexpression of autophagy-related (ATG) genes. Specifically, overexpression of ATG1, ATG3, ATG7, ATG17, ATG19, ATG23, ATG24 and ATG29 inhibited filamentous growth. From our understanding of autophagy in yeast, overexpression of these genes does not markedly affect the activity of the pathway; thus, we do not expect that this filamentous growth phenotype is due strictly to diminished nitrogen stress in ATG overexpression mutants. Rather, these results highlight an additional undefined regulatory mechanism linking autophagy and filamentous growth, possibly independent of the upstream nitrogen-sensing machinery feeding into both processes.

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Available from: Craig J Dobry, Jan 20, 2014
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    • "It should be noted that the affinity tags may perturb protein folding at the carboxy terminus of some of the gene products, but we expect that the majority of genes in this collection (80–90%) should encode fully functional proteins, extrapolating from large-scale protein localization and affinity purification studies (Gavin et al. 2002; Ho et al. 2002; Kumar et al. 2002a; Ghaemmaghami et al. 2003; Huh et al. 2003; Bharucha et al. 2008). To generate overexpression strains for phenotypic analysis of filamentous growth, we introduced the plasmids individually in 96-well format into a diploid strain of the filamentous S1278b genetic background by a modified form of lithium acetate-mediated transformation as described (Kumar et al. 2000, 2002b; Ma et al. 2007a,b; Bharucha et al. 2008; Jin et al. 2008). All transformants were selected on SC 2Ura, and glycerol stock solutions (15% glycerol) were prepared. "
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    • "In the fungus Podospora anserina, disruption of genes encoding Atg1 and Atg8 homologs resulted in similar phenotypic changes in growth and differentiation (Pinan-Lucarré et al., 2003). This is consistent with findings from Saccharomyces cerevisiae where disruption of different autophagy genes resulted in similar changes in phenotypic traits, e.g., inhibition of filamentous growth (Ma et al., 2007). "
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