Mitophagy and mitochondrial balance

Mitochondria are highly dynamic organelles, with a morphology ranging from small roundish elements to large interconnected networks. This fine architecture has a significant impact on mitochondrial homeostasis, and mitochondrial morphology is highly connected to specific cellular process. Autophagy is a catabolic process in which cell constituents, including proteins and organelles, are delivered to the lysosomal compartment for degradation. Autophagy has multiple physiological functions and recent advances have demonstrated that this process is linked to different human diseases, such as cancer and neurodegenerative disorders. In particular, it has been found that autophagy is a key determinant for the life span of mitochondria through a particularly fine-tuned mechanism called mitophagy, a selective form of autophagy, which ensures the preservation of healthy mitochondria through the removal of damaged or superfluous mitochondria. Mitophagy has been found to be altered in several pathologies and aberrant or excessive levels of this process are found in common human disorders. Thus, the measurement of the mitophagy levels is of fundamental relevance to elucidate the molecular mechanism of this process and, most importantly, its role in cellular homeostasis and disease. In this review, we will provide an overview of the current methods used to measure mitophagic levels, with particular emphasis on the techniques based on fluorescent probes.