Dataset Information

Role of STAT1 and Oxidative Stress in Gentamicin-Induced Hair Cell Death in Organ of Corti.

ABSTRACT: Oxidative stress plays a critical role in gentamicin-induced hair cell death. Previous work has implicated the cytoplasmic transcription factor signal transducer and activator of transcription 1 (STAT1) as a potential mediator of drug-induced ototoxicity, but role in aminoglycosides is largely unknown. This study investigated aminoglycosides-induced cell death, exploring contributions of reactive oxygen species and STAT1 pathway in injury and protection.Neonatal murine organ of Corti explants from 2 to 3 day postnatal pups (n?=?96) were treated with gentamicin at (4??M, 50??M) for 4 to 72 hours, with/without protectants. Effects on STAT1 pathway and gentamicin-induced hair cell death were measured with 50??M Epigallocatechin gallate (EGCG, a STAT1 inhibitor) and all-trans retinoic acid (atRA, a STAT1 activator). Hair cell morphology was evaluated and hair cell loss was quantified with cytocochleograms. Mitochondrial membrane potential was assayed and superoxide generation and suppression was measured with dihydroethidium (DHE) staining.Co-administration of 50??M EGCG conferred protection from 4??M gentamicin toxicity (p?

SUBMITTER: Jiang P

PROVIDER: S-EPMC5125081 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Role of STAT1 and Oxidative Stress in Gentamicin-Induced Hair Cell Death in Organ of Corti.

Jiang Peng P Ray Amrita A Rybak Leonard P LP Brenner Michael J MJ

Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology 20161001 9

<h4>Rationale</h4>Oxidative stress plays a critical role in gentamicin-induced hair cell death. Previous work has implicated the cytoplasmic transcription factor signal transducer and activator of transcription 1 (STAT1) as a potential mediator of drug-induced ototoxicity, but role in aminoglycosides is largely unknown. This study investigated aminoglycosides-induced cell death, exploring contributions of reactive oxygen species and STAT1 pathway in injury and protection.<h4>Methods</h4>Neonatal ...[more]

PMID: 27631653

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Project description:BackgroundHearing loss is the most common sensory defect afflicting several hundred million people worldwide. In most cases, regardless of the original cause, hearing loss is related to the degeneration and death of hair cells and their associated spiral ganglion neurons. Despite this knowledge, relatively few studies have reported regeneration of the auditory system. Significant gaps remain in our understanding of the molecular mechanisms underpinning auditory function, including the factors required for sensory cell regeneration. Recently, the identification of transcriptional activators and repressors of hair cell fate has been augmented by the discovery of microRNAs (miRNAs) associated with hearing loss. As miRNAs are central players of differentiation and cell fate, identification of miRNAs and their gene targets may reveal new pathways for hair cell regeneration, thereby providing new avenues for the treatment of hearing loss.ResultsIn order to identify new genetic elements enabling regeneration of inner ear sensory hair cells, next-generation miRNA sequencing (miRSeq) was used to identify the most prominent miRNAs expressed in the mouse embryonic inner ear cell line UB/OC-1 during differentiation towards a hair cell like phenotype. Based on these miRSeq results eight most differentially expressed miRNAs were selected for further characterization. In UB/OC-1, miR-210 silencing in vitro resulted in hair cell marker expression, whereas ectopic expression of miR-210 resulted in new hair cell formation in cochlear explants. Using a lineage tracing mouse model, transdifferentiation of supporting epithelial cells was identified as the likely mechanism for this new hair cell formation. Potential miR-210 targets were predicted in silico and validated experimentally using a miR-trap approach.ConclusionMiRSeq followed by ex vivo validation revealed miR-210 as a novel factor driving transdifferentiation of supporting epithelial cells to sensory hair cells suggesting that miR-210 might be a potential new factor for hearing loss therapy. In addition, identification of inner ear pathways regulated by miR-210 identified potential new drug targets for the treatment of hearing loss.

Project description:Inner ear hair cell death leads to sensorineural hearing loss and can be a direct consequence of aminoglycoside antibiotic treatment. Aminoglycosides such as gentamicin are effective therapy for serious Gram-negative bacterial infections such as some forms of meningitis, pneumonia, and sepsis. Aminoglycosides enter hair cells through mechanotransduction channels at the apical end of hair bundles and initiate intrinsic cell death cascades, but the precise cell signaling that leads to hair cell death is incompletely understood. Here, we examine the cell death pathways involved in aminoglycoside damage using the zebrafish (Danio rerio). The zebrafish lateral line contains hair cell-bearing organs called neuromasts that are homologous to hair cells of the mammalian inner ear and represents an excellent model to study ototoxicity. Based on previous research demonstrating a role for p53, Bcl2 signaling, autophagy, and proteasomal degradation in aminoglycoside-damaged hair cells, we used the Cytoscape GeneMANIA Database to identify additional proteins that might play a role in neomycin or gentamicin ototoxicity. Our bioinformatics analysis identified the pro-survival proteins phosphoinositide-dependent kinase-1 (PDK1) and X-linked inhibitor of apoptosis protein (Xiap) as potential mediators of gentamicin-induced hair cell damage. Pharmacological inhibition of PDK1 or its downstream mediator protein kinase C facilitated gentamicin toxicity, as did Xiap mutation, suggesting that both PI3K and endogenous Xiap confer protection. Surprisingly, aminoglycoside-induced hair cell death was highly attenuated in wild type Tupfel long-fin (TL fish; the background strain for the Xiap mutant line) compared to wild type ?AB zebrafish. Pharmacologic manipulation of p53 suggested that the strain difference might result from decreased p53 in TL hair cells, allowing for increased hair cell survival. Overall, our studies identified additional steps in the cell death cascade triggered by aminoglycoside damage, suggesting possible drug targets to combat hearing loss resulting from aminoglycoside exposure.

Dataset Information

Role of STAT1 and Oxidative Stress in Gentamicin-Induced Hair Cell Death in Organ of Corti.

Publications

Role of STAT1 and Oxidative Stress in Gentamicin-Induced Hair Cell Death in Organ of Corti.

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