title: NF-kappaB pathway protects cochlear hair cells from aminoglycoside-induced ototoxicity.
abstract: Cell death in outer hair cells of the mammalian inner ear induced by aminoglycoside antibiotics is mediated by reactive oxygen species (ROS) and can be prevented by antioxidants. The current study investigates the role of the nuclear factor (NF)-kappaB pathway in cell death or survival in adult CBA mice. Kanamycin (700 mg/kg subcutaneously, twice per day) progressively destroys hair cells but after 7 days of treatment auditory function and morphology are not yet affected significantly, permitting investigations of early events in drug-induced cell death. Immunostaining for 4-hydroxynonenal, indicative of lipid peroxidation, was elevated in the cochlea, but there was no effect on nitrotyrosine, a marker for peroxynitrite. NF-kappaB was increased at 3 hr, 3 days, and 7 days of treatment, with p50 and p65 proteins as its most abundant subunits. Immunoreactivity for p50 was present in nuclei of inner hair cells and supporting cells that survive the drug treatment. In contrast, nuclei of outer hair cells were devoid of label. Concomitant injections of antioxidants, however, such as 2,3-dihydroxybenzoic acid or salicylate (which prevent cell death induced by kanamycin), promoted the translocation of NF-kappaB into the nuclei of outer hair cells. In addition, kanamycin treatment decreased tyrosine phosphorylation of the inhibitory IkappaBalpha protein, leading to increased IkappaBalpha levels in the cochlea; the effect was reversed by cotreatment with antioxidants. These results suggest that changes in the redox state of the cochlea stimulate the activation of NF-kappaB and that this activation is cell protective.
authors.affiliation: Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan 48109-0506, USA.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Jiang
authors.forename: Su-Hua
authors.initials: SH
authors.lastname: Sha
authors.forename: Jochen
authors.initials: J
authors.lastname: Schacht
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001309:Auditory Threshold / Q000187:drug effects; D001562:Benzimidazoles / Q000378:metabolism; D015153:Blotting, Western / Q000379:methods; D002135:Calcium-Binding Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002458:Cell Fractionation / Q000379:methods; D003051:Cochlea / Q000166:cytology* / Q000473:pathology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D042522:DNA Replication Timing / Q000187:drug effects; D029721:Drosophila Proteins / Q000378:metabolism; D004334:Drug Administration Schedule; D004347:Drug Interactions; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D062385:Hydroxybenzoates / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D007502:Iron Chelating Agents / Q000494:pharmacology; D007612:Kanamycin / Q000494:pharmacology*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008808:Mice, Inbred CBA; D018832:Molecular Chaperones / Q000378:metabolism; D016328:NF-kappa B / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D020011:Protective Agents / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012459:Salicylates / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D050863:Synaptotagmin I; D050857:Synaptotagmins; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D000447:Aldehydes; D000900:Anti-Bacterial Agents; D001562:Benzimidazoles; D002135:Calcium-Binding Proteins; C513271:Cdc37 protein, mouse; D018797:Cell Cycle Proteins; D016861:Cyclooxygenase Inhibitors; D029721:Drosophila Proteins; D062385:Hydroxybenzoates; D007502:Iron Chelating Agents; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D020011:Protective Agents; D012333:RNA, Messenger; D012459:Salicylates; D050863:Synaptotagmin I; C036387:tyrosinamide; D050857:Synaptotagmins; C002744:3-nitrotyrosine; D014443:Tyrosine; D007612:Kanamycin; C009135:2,3-dihydroxybenzoic acid; C027576:4-hydroxy-2-nonenal; C017807:bisbenzimide ethoxide trihydrochloride