Autophagy and caspases: a new cell death program.

Autophagy is used to degrade components of the cytoplasm and functions as a cell survival mechanism during nutrient deprivation. Autophagic structures have also been observed in many types of dying cells, but experimental evidence for autophagy playing a role in the regulation of programmed cell death is limited. We have recently shown that the autophagy genes Atg7 and Beclin1 are required for the death of certain cells, thus demonstrating that this mechanism of proteolysis is involved in both survival and death. The factors that enable autophagy to regulate distinct cell survival and death responses are not clear, and future work is needed to determine the mechanism(s) that regulate autophagic cell death.