Monitoring H2S fluctuation during autophagic fusion of lysosomes and mitochondria using a lysosome-targeting fluorogenic probe

Hydrogen sulfide (H2S) plays a cytoprotective role during mitophagy by detoxifying superfluous reactive oxygen species (ROS), and its concentration fluctuates in this process. However, no work has been reported to reveal the variation in H2S levels during autophagic fusion of lysosomes and mitochondria. Herein, we present a lysosome-targeted fluorogenic probe, named NA-HS, for real-time monitoring of H2S fluctuation for the first time. The newly synthesized probe exhibits good selectivity and high sensitivity (detection limit of 23.6 nM). Fluorescence imaging results demonstrated that NA-HS could image exogenous and endogenous H2S in living cells. Interest-ingly, the colocalization results revealed that the level of H2S was upregulated after autophagy began because of the cytoprotective effect, and was finally gradually reduced during subsequent autophagic fusion. This work not only affords a powerful fluorescence tool to monitor the variations in H2S levels during mitophagy, but also offers new insights into targeting small molecules for elaborating the complex cellular signal pathways.

Automated summary

In this study, a lysosome-targeted fluorogenic probe called NA-HS was developed for real-time monitoring of hydrogen sulfide (H2S) fluctuation during autophagic fusion. The probe exhibited good selectivity and high sensitivity, allowing imaging of exogenous and endogenous H2S in living cells. Results showed that H2S levels were upregulated after autophagy initiation and gradually reduced during subsequent autophagic fusion, providing insights into cellular signal pathways.