Reticulophagy and nucleophagy: New findings and unsolved issues.

Autophagy targets various intracellular components ranging from proteins and nucleic acids to organelles for their degradation in lysosomes or vacuoles. In selective types of autophagy, receptor proteins play central roles in target selection. These proteins bind or localize to specific targets, and also interact with Atg8 family proteins on forming autophagosomal membranes, leading to the efficient sequestration of the targets by the membranes. Our recent study revealed that yeast cells actively degrade the endoplasmic reticulum (ER) and even part of the nucleus via selective autophagy under nitrogen-deprived conditions. We identified novel receptors, Atg39 and Atg40, specific to these pathways. Here, we summarize our findings on 'reticulophagy' (or 'ER-phagy') and 'nucleophagy', and discuss key issues that remain to be solved in future studies.