A high‐contrast autolysosome probe for detecting interaction between autophagosomes and autolysosomes in mitophagy

Comprehensive Summary Autophagy is a multi‐step cell metabolism process in which cells remove damaged and unwanted materials. During autophagy, autophagosomes fuse with lysosomes to form autophagosomes. Autophagosomal membrane components are recycled from autolysosomes through the autophagosomal components recycling (ACR), while lysosomal components circulate on the autolysosomal surface through the autophagic lysosome reformation (ALR) process. Autolysosomes contain components from autophagosomes and lysosomes. However, whether there is a fusion between autolysosome and autophagosome or lysosome at the organelle level remains unknown. In this study, a pH and viscosity dual‐controlled mitochondria‐targeting fluorescent probe Mito‐Q was designed based on an asymmetric norcyanine to achieve the high‐contrast imaging of mitochondria‐containing autolysosomes. Mito‐Q not only effectively detected mitochondrial viscosity changes and mitophagy with high sensitivity, but more importantly, the fusion of mitochondria‐containing autolysosomes and autophagosomes (FMAA) was observed during autophagy by the real‐time confocal imaging of HeLa cells.