An Aggregation/Monomer-Based Probe for Monitoring Mitochondria–Lysosome Interactions during Cuproptosis

The interplay between lysosomes and mitochondria is essential for maintaining cellular function, and disruptions of their interaction have been implicated in the onset of various diseases. Small molecule fluorescent probes are powerful tools for monitoring these biological processes. However, a comprehensive strategy for designing small-molecule probes capable of dual-color visualization of both mitochondria and lysosomes remains lacking. In this study, we introduce MISO, a noninvasive small organic molecular probe, as an effective tool for tracking the dynamic interplay between mitochondria and lysosomes in living cells. Mechanistic studies revealed that MISO targets lysosomes in a monomeric state, exhibiting green fluorescence, and in an aggregated state within mitochondria, displaying red fluorescence. Using MISO, we were able to perform long-term tracking of dynamic mitochondria–lysosome interactions and identified several distinct types of interactions between these organelles. Notably, for the first time, MISO revealed changes in mitochondria–lysosome interactions during cuproptosis, suggesting that the modulation of these interactions may influence this form of cell death. This work presents a valuable tool for real-time monitoring of functional mitochondria–lysosome interactions in living cells and opens avenues for advancing our understanding of related cellular processes and disease mechanisms.