Increased mitophagy protects cochlear hair cells from aminoglycoside-induced damage.

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.