Molecular mechanisms of autophagy and the effect of autophagy dysfunction on mitochondrial function

Abstract

Long lifespan of evolutionary higher organisms including humans is associated with the challenge to maintain viability of post mitotic cells, such as neurons, for decades. Autophagy is increasingly recognized as an important prosurvival pathway in oxidative and proteotoxic stress conditions. Autophagy degrades cytosolic macromolecules in response to starvation and is involved in the selective degradation of damaged/toxic organelles, such as mitochondria. With age autophagy function declines, and is also compromised in several neurodegenerative diseases. We identified a novel role for autophagy in the maintenance of mitochondrial health, specifically respiratory complex I. Intriguingly, galactose-induced cell death of autophagy deficient cells was rescued by preventing ROS production at complex I or bypassing complex I-linked respiration. We propose that aberrant ROS production via complex I in response to autophagy deficiency could be pathogenic and result in neurodegeneration and preventing this could be an interesting therapeutic target. Furthermore, we found that vertebrates have evolved mechanisms to induce autophagy in response to oxidative stress. This involves the oxidation of the autophagy receptor p62, which promotes autophagy flux and the clearance of autophagy cargo, resulting in increased stress resistance in mammalian cells and survival under stress in flies. In addition, we obtained data revealing an important role for redox-regulated cysteines in NDP52 for the degradation of mitochondria via mitophagy and tools were created to study the role of other autophagy receptors in autophagy initiation and selective autophagy.