Autophagy is a conserved pathway of cellular recycling and stress response. Recycling is initiated upon nutrient limitation, and it involves engulfing a non-selective portion of the cytosol (including organelles) into double-membrane autophagosomes for delivery to the lysosomes and degradation. This process, termed starvation-induced autophagy, generates nutrients and other essential elements during digestion, which can then be used for cell growth. Autophagy is also initiated as a stress response to eliminate internal superfluous or malfunctioning components or external invading pathogens. In both situations, autophagic degradation, termed selective autophagy, is a quality control process. It is essential for the health of most cells and tissues.

The formation of autophagosomes is a crucial step in autophagy. The main characteristic of starvation-induced autophagy is that it is a fast process that generates de novo hundreds of novel organelles (the autophagosomes) in the cytosol. The main feature of selective autophagy is that the forming autophagosomes usually target and engulf only specific cargo (for example, bacteria, mitochondria, endosomes, a portion of the endoplasmic reticulum, etc.). In most cases, they form sporadically and in small numbers during the process.

The autophagy pathway is not limited to the dynamics of the response and the substantial membrane rearrangements observed. It is eminently suited for microscopical approaches, either live imaging by light microscopy or higher resolution analysis by electron microscopy. Pioneering electron microscopy studies established the earliest parameters of this response and its recognition as a genuine cell biological.

The objective of this collection will be to collect in one place several techniques used to image autophagy at the light or electron microscopy level. Such a collection will benefit other labs that want to apply imaging techniques to study the pathway. In addition, it should also be helpful for cell biology labs not specifically interested in autophagy but membrane dynamics in general.