Imaging of Mitophagy Enabled by an Acidity-Reporting Probe Anchored on the Mitochondrial Inner Membrane

Classical chemical probes are prone to dissipation from stressed organelles, as evidenced by the incapability of mitochondrial dyes to image mitophagy linked to multiple diseases. We herein reported mitophagy imaging via covalent anchoring of a lysosomal probe to the mitochondrial inner membrane (CALM). Utilizing DBCORC-TPP, an azide-conjugatable probe with acidity-triggered fluorescence, CALM is operated via ATm-promoted probe accumulation in mitochondria and thereby bioorthogonal ligation of the trapped probe with azido-choline (Azcholine) metabolically installed on the mitochondrial membrane. Over-coming the limitation of synthetic probes to dissipate from stressed organelles, CALM enables signal-on fluorescence imaging of mitophagy induced by starvation and is further employed to reveal mitophagy in ferroptosis. These results suggest the potential of CALM as a new tool to study mitophagy.

Automated summary

CALM is a method for mitophagy imaging by covalently anchoring a lysosomal probe to the mitochondrial inner membrane, overcoming the limitation of synthetic probes to dissipate from stressed organelles. It enables signal-on fluorescence imaging and has the potential to study mitophagy induced by starvation and in ferroptosis.