Imaging HOCl Generation during the Mitochondria Peripheral Fission with a Tailor-Made Fluorescent Probe
Haolin Zhang1,2, Ya Liu1,3, Xiaofan Zhang1
1Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Abstract:
Mitochondrial fission is a highly regulated process that can affect metabolism, proliferation, and apoptosis. Division at the periphery enables damaged material to be shed into smaller mitochondria destined for mitophagy, which is found preceded by increased Ca2+ and reactive oxygen species, as well as reduced membrane potential and pH. However, the variation of hypochlorous acid (HOCl) during the peripheral fission has not been well studied, and the existing fluorescent probes are unsuitable for detecting mitochondrial HOCl because of the 0.8-fold decreased pH during this process. Herein, we design a novel CCS (changeable π-conjugation system)-based probe (ON-mito) with a dibenzo[1,4]oxazepine core, which can selectively react with HOCl at pH 6.4, generating an oxazine-containing product that emits at 660 nm. The capability of ON-mito for imaging the HOCl generation in HeLa cells during mitophagy is demonstrated under weakly acidic condition. Further, with ON-mito, we find for the first time a burst increase of the mitochondrial HOCl in COS-7 cells during peripheral fission, which may serve as an important indicator of this process. Probe ON-mito may be useful for studying mitochondrial damage under diverse conditions.
Insights
Researchers developed a new probe, ON-mito, to detect hypochlorous acid (HOCl) during mitochondrial fission. This probe enables the study of mitochondrial damage and mitophagy, revealing a key indicator of peripheral fission.
Area of Science:
- Mitochondrial biology and cellular imaging.
- Development of novel fluorescent probes for reactive oxygen species detection.
Background:
- Mitochondrial fission is crucial for cellular processes like metabolism, proliferation, and apoptosis.
- Peripheral fission facilitates the removal of damaged mitochondrial components via mitophagy.
- Existing probes are inadequate for detecting hypochlorous acid (HOCl) during mitophagy due to pH changes.
Purpose of the Study:
- To design and synthesize a novel fluorescent probe for selective HOCl detection in mitochondria.
- To investigate the role of HOCl during mitochondrial peripheral fission and mitophagy.
- To establish a new imaging tool for studying mitochondrial damage.
Main Methods:
- Design and synthesis of a changeable π-conjugation system (CCS)-based probe (ON-mito) with a dibenzo[1,4]oxazepine core.
- Characterization of ON-mito's selective reaction with HOCl at pH 6.4, producing a 660 nm emitting product.
- Application of ON-mito for imaging HOCl generation in HeLa cells during mitophagy and in COS-7 cells during peripheral fission.
Main Results:
- ON-mito successfully detected HOCl generation in HeLa cells under weakly acidic conditions during mitophagy.
- A significant burst increase in mitochondrial HOCl was observed in COS-7 cells during peripheral fission using ON-mito.
- The probe demonstrated suitability for imaging mitochondrial HOCl under conditions where other probes failed.
Conclusions:
- The novel ON-mito probe enables selective detection of mitochondrial HOCl at weakly acidic pH.
- Mitochondrial HOCl increase is identified as a potential indicator of peripheral fission.
- ON-mito offers a valuable tool for investigating mitochondrial damage and related cellular processes.
