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Increased mitophagy protects cochlear hair cells from aminoglycoside-induced damage
Yuhua Zhang1, Qiaojun Fang1, Hongfeng Wang2
1State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, Jiangsu, China.
Abstract:
Aminoglycosides exhibit ototoxicity by damaging mitochondria, which in turn generate reactive oxygen species that induce hair cell death and subsequent hearing loss. It is well known that damaged mitochondria are degraded by mitophagy, an important mitochondrial quality control system that maintains mitochondrial homeostasis and ensures cell survival. However, it is unclear whether dysregulation of mitophagy contributes to aminoglycoside-induced hair cell injury. In the current study, we found that PINK1-PRKN-mediated mitophagy was impaired in neomycin-treated hair cells. Our data suggested that mitochondrial recruitment of PRKN and phagophore recognition of damaged mitochondria during mitophagy were blocked following neomycin treatment. In addition, the degradation of damaged mitochondria by lysosomes was significantly decreased as indicated by the mitophagic flux reporter mt-mKeima. Moreover, we demonstrated that neomycin disrupted mitophagy through transcriptional inhibition of Pink1 expression, the key initiator of mitophagy. Moreover, we found that neomycin impaired mitophagy by inducing ATF3 expression. Importantly, treatment with a mitophagy activator could rescue neomycin-treated hair cells by increasing mitophagy, indicating that genetic modulation or drug intervention in mitophagy may have therapeutic potential for aminoglycoside-induced hearing loss.Abbreviations: AAV: adeno-associated virus; ABR: auditory brainstem response; ATF3: activating transcription factor 3; ATOH1/MATH1: atonal bHLH transcription factor 1; BafA1: bafilomycin A1; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; COX4I1/COXIV: cytochrome c oxidase subunit 4I1; CTBP2/RIBEYE: C-terminal binding protein 2; DFP: deferiprone; EGFP: enhanced green fluorescent protein; FOXO3: forkhead box O3; GRIA2/GLUR2: glutamate receptor, ionotropic, AMPA2 (alpha 2); HC: hair cell; HSPD1/HSP60: heat shock protein 1 (chaperonin); IHC: inner hair cell; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MYO7A: myosin VIIA; OPTN: optineurin; OMM: outer mitochondrial membrane; PRKN: parkin RBR E3 ubiquitin protein ligase; PINK1: PTEN induced putative kinase 1; RT-qPCR: real-time quantitative polymerase chain reaction; TOMM20/TOM20: translocase of outer mitochondrial membrane 20; TUNEL: Terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling; USP30: ubiquitin specific peptidase 30; XBP1: X-box binding protein 1.
Insights
Aminoglycoside ototoxicity impairs mitophagy, a cellular process that removes damaged mitochondria. Activating mitophagy can protect hair cells from this damage, suggesting a potential therapy for hearing loss.
Area of Science:
- Cell Biology
- Otolaryngology
- Mitochondrial Biology
Background:
- Aminoglycosides cause ototoxicity by damaging mitochondria, leading to hair cell death and hearing loss.
- Mitophagy is a crucial mitochondrial quality control pathway for cell survival.
- The role of mitophagy in aminoglycoside-induced hair cell injury remains unclear.
Purpose of the Study:
- To investigate the role of mitophagy in neomycin-induced hair cell injury.
- To elucidate the molecular mechanisms by which neomycin affects mitophagy.
- To explore the therapeutic potential of mitophagy modulation for aminoglycoside ototoxicity.
Main Methods:
- Neomycin treatment of hair cells.
- Assessment of mitophagy using PINK1-PRKN pathway markers.
- Measurement of mitophagic flux with mt-mKeima reporter.
- Analysis of Pink1 and ATF3 expression levels.
- Evaluation of mitophagy activator efficacy in rescuing hair cells.
Main Results:
- Neomycin treatment impaired PINK1-PRKN-mediated mitophagy in hair cells.
- Mitochondrial recruitment of PRKN and phagophore recognition were blocked.
- Lysosomal degradation of damaged mitochondria decreased, as shown by reduced mitophagic flux.
- Neomycin inhibited Pink1 expression transcriptionally and induced ATF3 expression.
- Mitophagy activator treatment rescued neomycin-damaged hair cells.
Conclusions:
- Dysregulation of PINK1-PRKN-mediated mitophagy contributes to aminoglycoside-induced hair cell injury.
- Neomycin disrupts mitophagy via transcriptional inhibition of Pink1 and induction of ATF3.
- Therapeutic strategies targeting mitophagy activation may offer a novel approach to prevent or treat aminoglycoside-induced hearing loss.
