Approaching the molecular mechanism of autophagy

Autophagy is a complex cellular process that involves dynamic membrane rear rangements under a range of physiological conditions. It is a highly regula ted process that plays a role in cellular maintenance and development, and has been implicated in a number of genetic diseases. Upon induction of auto phagy, cytoplasm is sequestered into vesicles and delivered to a degradativ e organelle, the vacuole in yeast or the lysosome in mammalian cells. The p rocess is unique in that it converts material that is topologically intrace llular into topologically extracellular. Autophagy was first described more than 50 years ago, but it is since the discovery of the pathway in yeast c ells that our knowledge about the molecular events taking place during the process has expanded. The generation of autophagy-specific mutants in a var iety of yeast cell lines has provided insight into functional roles of more than 15 novel genes, double that number if we include genes whose products function also in other processes. Although we have learned much about auto phagy, many questions remain to be answered. This review highlights the mos t recent advances in the autophagy field in both yeast and mammalian cells.