Mitochondrial calcium uptake underlies ROS generation during aminoglycoside-induced hair cell death
Robert Esterberg, … , Edwin W. Rubel, David W. Raible
Robert Esterberg, … , Edwin W. Rubel, David W. Raible
Published August 8, 2016
Citation Information: J Clin Invest. 2016;126(9):3556-3566. https://doi.org/10.1172/JCI84939.
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Research Article Otology

Mitochondrial calcium uptake underlies ROS generation during aminoglycoside-induced hair cell death

Abstract

Exposure to aminoglycoside antibiotics can lead to the generation of toxic levels of reactive oxygen species (ROS) within mechanosensory hair cells of the inner ear that have been implicated in hearing and balance disorders. Better understanding of the origin of aminoglycoside-induced ROS could focus the development of therapies aimed at preventing this event. In this work, we used the zebrafish lateral line system to monitor the dynamic behavior of mitochondrial and cytoplasmic oxidation occurring within the same dying hair cell following exposure to aminoglycosides. The increased oxidation observed in both mitochondria and cytoplasm of dying hair cells was highly correlated with mitochondrial calcium uptake. Application of the mitochondrial uniporter inhibitor Ru360 reduced mitochondrial and cytoplasmic oxidation, suggesting that mitochondrial calcium drives ROS generation during aminoglycoside-induced hair cell death. Furthermore, targeting mitochondria with free radical scavengers conferred superior protection against aminoglycoside exposure compared with identical, untargeted scavengers. Our findings suggest that targeted therapies aimed at preventing mitochondrial oxidation have therapeutic potential to ameliorate the toxic effects of aminoglycoside exposure.

Authors

Robert Esterberg, Tor Linbo, Sarah B. Pickett, Patricia Wu, Henry C. Ou, Edwin W. Rubel, David W. Raible

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Figure 3

Timing of cytoplasmic oxidation (HyPer) relative to mitochondrial membrane potential (TMRE) in dying hair cells exposed to aminoglycosides.

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Timing of cytoplasmic oxidation (HyPer) relative to mitochondrial membra...
(A) Mean HyPer fluorescence in dying lateral line hair cells colabeled with TMRE and exposed to 400 μM neomycin. Data are aligned to TMREhalf-min, corresponding to dye redistribution from mitochondria into cytoplasm. (B) Mean cross-correlation values of HyPer relative to TMRE. An offset of t = 0 indicates that the events are inseparable. In this case, maximal cross-correlation value (R) was at 0 minutes (r = 0.401, P = 0.011), indicating that the initial onset of increased HyPer fluorescence coincides with the onset of increased TMRE fluorescence. Error bars = SEM; n = 39 cells from 1 to 3 neuromasts per animal and 5 animals.