Autophagy and cell death in model organisms

Autophagy evolved in unicellular eukaryotes as a means for surviving nutrient stress. During the course of evolution, as multicellular organisms developed specialized cell types and complex intracellular signalling networks, autophagy has been summoned to serve additional cellular functions. Numerous recent studies indicate that apart from its pro-survival role under nutrient limitation, autophagy also participates in cell death. However, the precise role of this catabolic process in dying cells is not fully understood. Although in certain situations autophagy has a protective function, in other types of cell death it actually contributes to cellular destruction. Simple model organisms ranging from the unicellular Saccharomyces cerevisiae to the soil amoeba Dictyostelium discoideum and the metazoans Caenorhabditis elegans and Drosophila melanogaster provide clearly defined cell death paradigms that can be used to dissect the involvement of autophagy in cell death, at the molecular level. In this review, we survey current research in simple organisms, linking autophagy to cell death and discuss the complex interplay between autophagy, cell survival and cell death.