Autophagy is required for G1/G0quiescence in response to nitrogen starvation in Saccharomyces cerevisiae

Abstract

In response to starvation, cells undergo increased levels of autophagy and cell cycle arrest but the role of autophagy in starvation-induced cell cycle arrest is not fully understood. Here we show that autophagy genes regulate cell cycle arrest in the budding yeast Saccharomyces cerevisiae during nitrogen starvation. While exponentially growing wild-type yeasts preferentially arrest in G1/G0in response to starvation, yeasts carrying null mutations in autophagy genes show a significantly higher percentage of cells in G2/M. In these autophagy-deficient yeast strains, starvation elicits physiological properties associated with quiescence, such as Snf1 activation, glycogen and trehalose accumulation as well as heat-shock resistance. However, while nutrient-starved wild-type yeasts finish the G2/M transition and arrest in G1/G0, autophagy-deficient yeasts arrest in telophase. Our results suggest that autophagy is crucial for mitotic exit during starvation and appropriate entry into a G1/G0quiescent state.