Autophagy and aging--when "all you can eat" is yourself.

A recent paper provides evidence that macroautophagy is an essential downstream pathway for one of the mutations known to extend life span. Autophagy, or the degradation of intracellular components by the lysosomal system, was thought for a long time to be a catabolic process responsible for cellular cleanup. However, in recent years, we have learned that autophagy comes in different sizes and shapes, macroautophagy being one of them, and that this cellular maid plays many more roles than previously anticipated. Activation of autophagy is essential in physiological processes as diverse as morphogenesis, cellular differentiation, tissue remodeling, and cellular defense, among others. Furthermore, its participation in different pathological conditions, including cancer and neurodegeneration, is presently a subject of intense investigation. A role in aging has now been added to this growing list of autophagy functions. The activity of different forms of autophagy decreases with age, and this reduced function has been blamed for the accumulation of damaged proteins in old organisms. Research such as that covered in this Perspective shows that there is much more than trash to worry about when autophagy is not functioning properly.