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Adeyemo AA, Adedokun B, Adeolu J, Akinyemi JO, Omotade OO, Oluwatosin OM. Re-telling the story of aminoglycoside ototoxicity: tales from sub-Saharan Africa. Front Neurol 2024; 15:1412645. [PMID: 39006231 PMCID: PMC11239550 DOI: 10.3389/fneur.2024.1412645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 06/12/2024] [Indexed: 07/16/2024] Open
Abstract
Background Aminoglycosides, such as Streptomycin, are cheap, potent antibiotics widely used Sub-Saharan Africa. However, aminoglycosides are the commonest cause of ototoxicity. The limited prospective epidemiological studies on aminoglycoside ototoxicity from Sub-Saharan Africa motivated this study to provide epidemiological information on Streptomycin-induced ototoxicity, identify risk factors and predictors of ototoxicity. Method A longitudinal study of 153 adults receiving Streptomycin-based anti-tuberculous drugs was done. All participants underwent extended frequency audiometry and had normal hearing thresholds at baseline. Hearing thresholds were assessed weekly for 2 months, then monthly for the subsequent 6 months. Ototoxicity was determined using the ASHA criteria. Descriptive statistics were used to analyze socio-demographic variables. Ototoxicity incidence rate was calculated, and Kaplan-Meier estimate used to determine cumulative probability of ototoxicity. Chi-square test was done to determine parameters associated with ototoxicity and Cox regression models were used to choose the predictors of ototoxicity. Results Age of participants was 41.43 ± 12.66 years, with a male-to-female ratio of 1:0.6. Ototoxicity was found in 34.6% of the participants, giving an incidence of 17.26 per 1,000-person-week. The mean onset time to ototoxicity was 28.0 ± 0.47 weeks. By 28th week, risk of developing ototoxicity for respondents below 40 years of age was 0.29, and for those above 40 years was 0.77. At the end of the follow-up period, the overall probability of developing ototoxicity in the study population was 0.74. A significant difference in onset of ototoxicity was found between the age groups: the longest onset was seen in <40 years, followed by 40-49 years, and shortest onset in ≥50 years. Hazard of ototoxicity was significantly higher in participants aged ≥50 years compared to participants aged ≤40 years (HR = 3.76, 95% CI = 1.84-7.65). The probability of ototoxicity at 40 g, 60 g and 80 g cumulative dose of Streptomycin was 0.08, 0.43 and 2.34, respectively. Age and cumulative dose were significant predictors of ototoxicity. Conclusion The mean onset time to Streptomycin-induced ototoxicity was 28 weeks after commencement of therapy. Age and cumulative dose can reliably predict the onset of Streptomycin-induced ototoxicity. Medium to long term monitoring of hearing is advised for patients on aminoglycoside therapy.
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Affiliation(s)
- Adebolajo A Adeyemo
- Institute of Child Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
- Department of Otolaryngology, University College Hospital, Ibadan, Nigeria
| | - Babatunde Adedokun
- Department of Epidemiology and Medical Statistics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Josephine Adeolu
- Institute of Child Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Joshua O Akinyemi
- Department of Epidemiology and Medical Statistics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Olayemi O Omotade
- Institute of Child Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Odunayo M Oluwatosin
- Department of Surgery, College of Medicine, University of Ibadan, Ibadan, Nigeria
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2
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Gunn NJ, Kidd SP, Solomon LB, Yang D, Roscioli E, Atkins GJ. Staphylococcus aureus persistence in osteocytes: weathering the storm of antibiotics and autophagy/xenophagy. Front Cell Infect Microbiol 2024; 14:1403289. [PMID: 38915921 PMCID: PMC11194354 DOI: 10.3389/fcimb.2024.1403289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/17/2024] [Indexed: 06/26/2024] Open
Abstract
Staphylococcus aureus is a major causative pathogen of osteomyelitis. Intracellular infections of resident bone cells including osteocytes can persist despite gold-standard clinical intervention. The mechanisms by which intracellular S. aureus evades antibiotic therapy are unknown. In this study, we utilised an in vitro S. aureus infection model of human osteocytes to investigate whether antibiotic-mediated dysregulation of autophagy contributes to this phenomenon. Infected or non-infected osteocyte-like cells were exposed to combinations of rifampicin, vancomycin, and modulators of autophagy. Intracellular bacterial growth characteristics were assessed using colony-forming unit (CFU) analysis, viable bacterial DNA abundance, and the rate of escape into antibiotic-free medium, together with measures of autophagic flux. Rifampicin, alone or in combination with vancomycin, caused a rapid decrease in the culturability of intracellular bacteria, concomitant with stable or increased absolute bacterial DNA levels. Both antibiotics significantly inhibited autophagic flux. However, modulation of autophagic flux did not affect viable bacterial DNA levels. In summary, autophagy was shown to be a factor in the host-pathogen relationship in this model, as its modulation affected the growth state of intracellular S. aureus with respect to both their culturability and propensity to escape the intracellular niche. While rifampicin and vancomycin treatments moderately suppressed autophagic flux acutely, this did not explain the paradoxical response of antibiotic treatment in decreasing S. aureus culturability whilst failing to clear bacterial DNA and hence intracellular bacterial load. Thus, off-target effects of rifampicin and vancomycin on autophagic flux in osteocyte-like cells could not explain the persistent S. aureus infection in these cells.
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Affiliation(s)
- Nicholas J. Gunn
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Stephen P. Kidd
- Australian Centre for Antimicrobial Resistance Ecology, University of Adelaide, Adelaide, SA, Australia
- Research Centre for Infectious Disease, School of Biological Science, University of Adelaide, Adelaide, SA, Australia
| | - Lucian B. Solomon
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
- Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, SA, Australia
| | - Dongqing Yang
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Eugene Roscioli
- Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, SA, Australia
- Department of Medicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
- Centre for Cancer Biology, South Australia (SA) Pathology and University of South Australia, Adelaide, SA, Australia
| | - Gerald J. Atkins
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
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Wu W, Chen P, Yang J, Liu Y. A Low Dose of Rapamycin Promotes Hair Cell Differentiation by Enriching SOX2 + Progenitors in the Neonatal Mouse Inner Ear Organoids. J Assoc Res Otolaryngol 2024; 25:149-165. [PMID: 38472516 PMCID: PMC11018585 DOI: 10.1007/s10162-024-00938-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
PURPOSE To investigate the impact of rapamycin on the differentiation of hair cells. METHODS Murine cochlear organoids were derived from cochlear progenitor cells. Different concentrations of rapamycin were added into the culture medium at different proliferation and differentiation stages. RESULTS Rapamycin exhibited a concentration-dependent reduction in the proliferation of these inner ear organoids. Nevertheless, organoids subjected to a 10-nM dose of rapamycin demonstrated a markedly increased proportion of hair cells. Furthermore, rapamycin significantly upregulated the expression of markers associated with both hair cells and supporting cells, including ATOH1, MYO7A, and SOX2. Mechanistic studies revealed that rapamycin preferentially suppressed cells without Sox2 expression during the initial proliferation stage, thereby augmenting and refining the population of SOX2+ progenitors. These enriched progenitors were predisposed to differentiate into hair cells during the later stages of organoid development. Conversely, the use of the mTOR activator MHY 1485 demonstrated opposing effects. CONCLUSION Our findings underscore a practical strategy for enhancing the generation of inner ear organoids with a low dose of rapamycin, achieved by enriching SOX2+ progenitors in an in vitro setting.
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Affiliation(s)
- Wenjin Wu
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Penghui Chen
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Jun Yang
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Yupeng Liu
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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4
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Zou T, Xie R, Huang S, Lu D, Liu J. Potential role of modulating autophagy levels in sensorineural hearing loss. Biochem Pharmacol 2024; 222:116115. [PMID: 38460910 DOI: 10.1016/j.bcp.2024.116115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 02/20/2024] [Accepted: 03/06/2024] [Indexed: 03/11/2024]
Abstract
In recent years, extensive research has been conducted on the pathogenesis of sensorineural hearing loss (SNHL). Apoptosis and necrosis have been identified to play important roles in hearing loss, but they cannot account for all hearing loss. Autophagy, a cellular process responsible for cell self-degradation and reutilization, has emerged as a significant factor contributing to hearing loss, particularly in cases of autophagy deficiency. Autophagy plays a crucial role in maintaining cell health by exerting cytoprotective and metabolically homeostatic effects in organisms. Consequently, modulating autophagy levels can profoundly impact the survival, death, and regeneration of cells in the inner ear, including hair cells (HCs) and spiral ganglion neurons (SGNs). Abnormal mitochondrial autophagy has been demonstrated in animal models of SNHL. These findings indicate the profound significance of comprehending autophagy while suggesting that our perspective on this cellular process holds promise for advancing the treatment of SNHL. Thus, this review aims to clarify the pathogenic mechanisms of SNHL and the role of autophagy in the developmental processes of various cochlear structures, including the greater epithelial ridge (GER), SGNs, and the ribbon synapse. The pathogenic mechanisms of age-related hearing loss (ARHL), also known as presbycusis, and the latest research on autophagy are also discussed. Furthermore, we underscore recent findings on the modulation of autophagy in SNHL induced by ototoxic drugs. Additionally, we suggest further research that might illuminate the complete potential of autophagy in addressing SNHL, ultimately leading to the formulation of pioneering therapeutic strategies and approaches for the treatment of deafness.
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Affiliation(s)
- Ting Zou
- Department of Otorhinolaryngology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Renwei Xie
- Department of Otorhinolaryngology, Renhe Hospital, Baoshan District, Shanghai, China
| | - Sihan Huang
- Department of Otorhinolaryngology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Dingkun Lu
- Cardiac Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jun Liu
- Department of Otorhinolaryngology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
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5
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Lee YY, Ha J, Kim YS, Ramani S, Sung S, Gil ES, Choo OS, Jang JH, Choung YH. Abnormal Cholesterol Metabolism and Lysosomal Dysfunction Induce Age-Related Hearing Loss by Inhibiting mTORC1-TFEB-Dependent Autophagy. Int J Mol Sci 2023; 24:17513. [PMID: 38139347 PMCID: PMC10743727 DOI: 10.3390/ijms242417513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/07/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Cholesterol is a risk factor for age-related hearing loss (ARHL). However, the effect of cholesterol on the organ of Corti during the onset of ARHL is unclear. We established a mouse model for the ARHL group (24 months, n = 12) and a young group (6 months, n = 12). Auditory thresholds were measured in both groups using auditory brainstem response (ABR) at frequencies of 8, 16, and 32 kHz. Subsequently, mice were sacrificed and subjected to histological analyses, including transmission electron microscopy (TEM), H&E, Sudan Black B (SBB), and Filipin staining, as well as biochemical assays such as IHC, enzymatic analysis, and immunoblotting. Additionally, mRNA extracted from both young and aged cochlea underwent RNA sequencing. To identify the mechanism, in vitro studies utilizing HEI-OC1 cells were also performed. RNA sequencing showed a positive correlation with increased expression of genes related to metabolic diseases, cholesterol homeostasis, and target of rapamycin complex 1 (mTORC1) signaling in the ARHL group as compared to the younger group. In addition, ARHL tissues exhibited increased cholesterol and lipofuscin aggregates in the organ of Corti, lateral walls, and spiral ganglion neurons. Autophagic flux was inhibited by the accumulation of damaged lysosomes and autolysosomes. Subsequently, we observed a decrease in the level of transcription factor EB (TFEB) protein, which regulates lysosomal biosynthesis and autophagy, together with increased mTORC1 activity in ARHL tissues. These changes in TFEB and mTORC1 expression were observed in a cholesterol-dependent manner. Treatment of ARHL mice with atorvastatin, a cholesterol synthesis inhibitor, delayed hearing loss by reducing the cholesterol level and maintaining lysosomal function and autophagy by inhibiting mTORC1 and activating TFEB. The above findings were confirmed using stress-induced premature senescent House Ear Institute organ of Corti 1 (HEI-OC1) cells. The findings implicate cholesterol in the pathogenesis of ARHL. We propose that atorvastatin could prevent ARHL by maintaining lysosomal function and autophagy by inhibiting mTORC1 and activating TFEB during the aging process.
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Affiliation(s)
- Yun Yeong Lee
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
| | - Jungho Ha
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
- Department of Medical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Republic of Korea
| | - Young Sun Kim
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
| | - Sivasubramanian Ramani
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
| | - Siung Sung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
- Department of Medical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Republic of Korea
| | - Eun Sol Gil
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
- Department of Medical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Republic of Korea
| | - Oak-Sung Choo
- Department of Otorhinolaryngology-Head and Neck Surgery, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul 07441, Republic of Korea;
| | - Jeong Hun Jang
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
| | - Yun-Hoon Choung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea; (Y.Y.L.); (J.H.); (Y.S.K.); (S.R.); (S.S.); (J.H.J.)
- Department of Medical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Republic of Korea
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6
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Abstract
Orchestration of protein production and degradation and the regulation of protein lifetimes play a central role in many basic biological processes. Nearly all mammalian proteins are replenished by protein turnover in waves of synthesis and degradation. Protein lifetimes in vivo are typically measured in days, but a small number of extremely long-lived proteins (ELLPs) persist for months or even years. ELLPs are rare in all tissues but are enriched in tissues containing terminally differentiated post-mitotic cells and extracellular matrix. Consistently, emerging evidence suggests that the cochlea may be particularly enriched in ELLPs. Damage to ELLPs in specialized cell types, such as crystallin in the lens cells of the eye, causes organ failure such as cataracts. Similarly, damage to cochlear ELLPs is likely to occur with many insults, including acoustic overstimulation, drugs, anoxia, and antibiotics, and may play an underappreciated role in hearing loss. Furthermore, hampered protein degradation may contribute to acquired hearing loss. In this review, I highlight our knowledge of the lifetimes of cochlear proteins with an emphasis on ELLPs and the potential contribution that impaired cochlear protein degradation has on acquired hearing loss and the emerging relevance of ELLPs.
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Affiliation(s)
- Jeffrey N Savas
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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7
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Zhou Y, Li Y, Tao R, Li J, Fang L, Xiao S. Porcine Reproductive and Respiratory Syndrome Virus nsp5 Induces Incomplete Autophagy by Impairing the Interaction of STX17 and SNAP29. Microbiol Spectr 2023; 11:e0438622. [PMID: 36815765 PMCID: PMC10101144 DOI: 10.1128/spectrum.04386-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/02/2023] [Indexed: 02/24/2023] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is an economically important pathogen that has devastated the worldwide swine industry for over 30 years. Autophagy is an evolutionarily conserved intracellular lysosomal degradation pathway, and previous studies have documented that PRRSV infection prompts autophagosome accumulation. However, whether PRRSV induces complete or incomplete autophagy remains controversial. Here, we demonstrated that overexpression of PRRSV nonstructural protein 5 (nsp5) induced the accumulation of autophagosomes, and a similar scenario was observed in PRRSV-infected cells. Moreover, both PRRSV infection and nsp5 overexpression activated incomplete autophagy, as evidenced by the blockage of autophagosome-lysosome fusion. Mechanistically, nsp5 overexpression, as well as PRRSV infection, inhibited the interaction of syntaxin 17 (STX17) with synaptosomal-associated protein 29 (SNAP29), two SNARE proteins that mediate autophagosome fusion with lysosomes, to impair the formation of autolysosomes. We further confirmed that nsp5 interacted with STX17, rather than SANP29, and the interacting domains of STX17 were the N-terminal motif and SNARE motif. Taken together, the findings of our study suggest a mechanism by which PRRSV induces incomplete autophagy by blocking autophagosome degradation and provide insights into the development of new therapeutics to combat PRRSV infection. IMPORTANCE A substantial number of viruses have been demonstrated to utilize or hijack autophagy to benefit their replication. In the case of porcine reproductive and respiratory syndrome virus (PRRSV), previous studies have demonstrated the proviral effects of autophagy on PRRSV proliferation. Thus, an investigation of the mechanism by which PRRSV regulates the autophagy processes can provide new insight into viral pathogenesis. Autophagic flux is a dynamic process that consists of autophagosome formation and subsequent lysosomal degradation. However, the exact effect of PRRSV infection on the autophagic flux remains disputed. In this study, we demonstrated that PRRSV infection, as well as PRRSV nsp5 overexpression, inhibited the interaction of STX17 with SNAP29 to impair the fusion of autophagosomes with lysosomes, thereby blocking autophagic flux. This information will help us to understand PRRSV-host interactions and unravel new targets for PRRS prevention and control.
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Affiliation(s)
- Yanrong Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Yang Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Ran Tao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Jia Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
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Finding the balance: The elusive mechanisms underlying auditory hair cell mitochondrial biogenesis and mitophagy. Hear Res 2023; 428:108664. [PMID: 36566644 DOI: 10.1016/j.heares.2022.108664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 11/23/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022]
Abstract
In all cell types, mitochondrial biogenesis is balanced with mitophagy to maintain a healthy mitochondrial pool that sustains specific energetic demands. Cell types that have a higher energetic burden, such as skeletal muscle cells and cardiomyocytes, will subsequently develop high mitochondrial volumes. In these cells, calcium influx during activity triggers cascades leading to activation of the co-transcriptional regulation factor PGC-1α, a master regulator of mitochondrial biogenesis, in a well-defined pathway. Despite the advantages in ATP production, high mitochondrial volumes might prove to be perilous, as it increases exposure to reactive oxygen species produced during oxidative phosphorylation. Mechanosensory hair cells are highly metabolically active cells, with high total mitochondrial volumes to meet that demand. However, the mechanisms leading to expansion and maintenance of the hair cell mitochondrial pool are not well defined. Calcium influx during mechanotransduction and synaptic transmission regulate hair cell mitochondria, leading to a possibility that similar to skeletal muscle and cardiomyocytes, intracellular calcium underlies the expansion of the hair cell mitochondrial volume. This review briefly summarizes the potential mechanisms underlying mitochondrial biogenesis in other cell types and in hair cells. We propose that hair cell mitochondrial biogenesis is primarily product of cellular differentiation rather than calcium influx, and that the hair cell high mitochondrial volume renders them more susceptible to reactive oxygen species increased by calcium flux than other cell types.
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Wan H, Zhang Y, Hua Q. Cellular autophagy, the compelling roles in hearing function and dysfunction. Front Cell Neurosci 2022; 16:966202. [PMID: 36246522 PMCID: PMC9561951 DOI: 10.3389/fncel.2022.966202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/14/2022] [Indexed: 11/21/2022] Open
Abstract
Sensorineural hearing loss (SNHL) is currently a major health issue. As one of the most common neurodegenerative diseases, SNHL is associated with the degradation of hair cells (HCs), spiral ganglion neurons (SGNs), the stria vascularis, supporting cells and central auditory system cells. Autophagy is a highly integrated cellular system that eliminates impaired components and replenishes energy to benefit cellular homeostasis. Etiological links between autophagy alterations and neurodegenerative diseases, such as SNHL, have been established. The hearing pathway is complex and depends on the comprehensive functions of many types of tissues and cells in auditory system. In this review, we discuss the roles of autophagy in promoting and inhibiting hearing, paying particular attention to specific cells in the auditory system, as discerned through research. Hence, our review provides enlightening ideas for the role of autophagy in hearing development and impairment.
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Affiliation(s)
- Huanzhi Wan
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Research Institute of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yuanyuan Zhang
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Research Institute of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- *Correspondence: Yuanyuan Zhang,
| | - Qingquan Hua
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Research Institute of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Qingquan Hua,
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Li J, Liu C, Müller U, Zhao B. RIPOR2-mediated autophagy dysfunction is critical for aminoglycoside-induced hearing loss. Dev Cell 2022; 57:2204-2220.e6. [PMID: 36113482 PMCID: PMC9529990 DOI: 10.1016/j.devcel.2022.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 07/25/2022] [Accepted: 08/23/2022] [Indexed: 01/18/2023]
Abstract
Aminoglycosides (AGs) are potent antibiotics that are capable of treating a wide variety of life-threatening infections; however, they are ototoxic and cause irreversible damage to cochlear hair cells. Despite substantial progress, little is known about the molecular pathways critical for hair cell function and survival that are affected by AG exposure. We demonstrate here that gentamicin, a representative AG antibiotic, binds to and within minutes triggers translocation of RIPOR2 in murine hair cells from stereocilia to the pericuticular area. Then, by interacting with a central autophagy component, GABARAP, RIPOR2 affects autophagy activation. Reducing the expression of RIPOR2 or GABARAP completely prevents AG-induced hair cell death and subsequent hearing loss in mice. Additionally, abolishing the expression of PINK1 or Parkin, two key mitochondrial autophagy proteins, prevents hair cell death and subsequent hearing loss caused by AG. In summary, our study demonstrates that RIPOR2-mediated autophagic dysfunction is essential for AG-induced hearing loss.
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Affiliation(s)
- Jinan Li
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Chang Liu
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Bo Zhao
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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11
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Vijayakumar KA, Cho GW, Maharajan N, Jang CH. A Review on Peripheral Tinnitus, Causes, and Treatments from the Perspective of Autophagy. Exp Neurobiol 2022; 31:232-242. [PMID: 36050223 PMCID: PMC9471415 DOI: 10.5607/en22002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 08/03/2022] [Accepted: 08/10/2022] [Indexed: 01/18/2023] Open
Abstract
Tinnitus is the perception of phantom noise without any external auditory sources. The degeneration of the function or activity of the peripheral or central auditory nervous systems is one of the causes of tinnitus. This damage has numerous causes, such as loud noise, aging, and ototoxicity. All these sources excite the cells of the auditory pathway, producing reactive oxygen species that leads to the death of sensory neural hair cells. This causes involuntary movement of the tectorial membrane, resulting in the buzzing noise characteristic of tinnitus. Autophagy is an evolutionarily conserved catabolic scavenging activity inside a cell that has evolved as a cell survival mechanism. Numerous studies have demonstrated the effect of autophagy against oxidative stress, which is one of the reasons for cell excitation. This review compiles several studies that highlight the role of autophagy in protecting sensory neural hair cells against oxidative stress-induced damage. This could facilitate the development of strategies to treat tinnitus by activating autophagy.
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Affiliation(s)
- Karthikeyan A Vijayakumar
- Department of Biology, College of Natural Science, Chosun University, Gwangju 61452, Korea.,BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Korea
| | - Gwang-Won Cho
- Department of Biology, College of Natural Science, Chosun University, Gwangju 61452, Korea.,BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Korea
| | - Nagarajan Maharajan
- Department of Biology, College of Natural Science, Chosun University, Gwangju 61452, Korea.,BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Korea
| | - Chul Ho Jang
- Department of Otolaryngology, Chonnam National University Medical School, Gwangju 61469, Korea
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12
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Pravastatin Administration Alleviates Kanamycin-Induced Cochlear Injury and Hearing Loss. Int J Mol Sci 2022; 23:ijms23094524. [PMID: 35562915 PMCID: PMC9105065 DOI: 10.3390/ijms23094524] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/13/2022] [Accepted: 04/18/2022] [Indexed: 11/23/2022] Open
Abstract
The effect of statins on aminoglycoside-induced ototoxicity is controversial. This study aimed to explore the role of pravastatin (PV) in kanamycin-induced hearing loss in rats. Adult rats were intraperitoneally treated with 20 mg/kg/day of kanamycin (KM) for 10 days. In the PV- and PV + KM-treated rats, 25 mg/kg/day of PV was intraperitoneally administered for 5 days. The auditory brainstem response (ABR) thresholds were measured before and after drug treatment using a smartEP system at 4, 8, 16, and 32 kHz. Cochlear changes in poly ADP-ribose (PAR) polymerase (PARP), PAR, and caspase 3 were estimated using Western blotting. PV administration did not increase the ABR thresholds. The KM-treated rats showed elevated ABR thresholds at 4, 8, 16, and 32 kHz. The PV + KM-treated rats demonstrated lower ABR thresholds than the KM-treated rats at 4, 8, and 16 kHz. The cochlear outer hair cells and spiral ganglion cells were relatively preserved in the PV + KM-treated rats when compared with that in the KM-treated rats. The cochlear expression levels of PARP, PAR, and caspase 3 were higher in the KM-treated rats. The PV + KM-treated rats showed lower levels of PARP, PAR, and caspase 3 than the KM-treated rats. PV protected cochleae from KM-induced hearing loss in rats. The regulation of autophagy and apoptosis mediated the otoprotective effects of PV.
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Aydemir F, Ulku CH, Elmas C, Seymen CM. Analysis of potential protective effects of caffeic acid phenethyl ester against gentamicin ototoxicity: An experimental study. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2022; 25:121-125. [PMID: 35656452 PMCID: PMC9118274 DOI: 10.22038/ijbms.2022.60794.13467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/15/2021] [Indexed: 12/04/2022]
Abstract
OBJECTIVES In this study, it is aimed to investigate the potential protective effect of caffeic acid phenethyl ester (CAPE) on ototoxicity caused by gentamicin in a rat model. MATERIALS AND METHODS Thirty Wistar albino rats were divided into 3 groups. Group I was selected as the control group. Gentamicin was administered intraperitoneally in group II, gentamicin and CAPE in group III. Audiological assessment was performed by the distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) measurements before and after treatment of each group. At the end of the study all rats were decapitated, cochlea was removed and electron microscopic examination was performed. RESULTS In group II post-treatment DPOAE levels were found to be lower than pretreatment DPOAE levels (P<0.05). However, in group III, there is no significant difference between pre- and post-treatment DPOAE levels (P>0.05). Except for Group I, ABR thresholds increased after the procedure and this increase was statistically significant (P<0.0001). According to histological examination by transmission electron microscopy, CAPE has a cellular protective effect against gentamicin ototoxicity. CONCLUSION CAPE may ameliorate hearing deterioration caused by gentamicin ototoxicity and protect the cochlear cells from apoptosis due to the strong antioxidant effect.
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Affiliation(s)
- Fuat Aydemir
- Department of Otorhinolaryngology, Kulu State Hospital, Konya, Turkey,Corresponding author: Fuat Aydemir. Department of Otorhinolaryngology, Kulu State Hospital, Konya, Turkey. Tel :+90 5062438106; Fax: +90 332 641 01 04;
| | - Cagatay Han Ulku
- Department of Otorhinolaryngology, Necmettin Erbakan University Meram Faculty of Medicine, Konya, Turkey
| | - Cigdem Elmas
- Department of Histology and Embryology, Gazi University Faculty of Medicine, Ankara, Turkey
| | - Cemile Merve Seymen
- Department of Histology and Embryology, Gazi University Faculty of Medicine, Ankara, Turkey
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Reis AD, Dalmolin SP, Saul DDA, Machado MS, Dallegrave E. Ototoxicity of an association of insecticides compounds containing dichlorvos and cypermethrin in Wistar rats. REVISTA CEFAC 2022. [DOI: 10.1590/1982-0216/20222424522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Aléxia dos Reis
- Universidade Federal de Ciências da Saúde de Porto Alegre, Brazil
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15
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Wang H, Li J, Qin J, Li J, Chen Y, Song D, Zeng H, Wang S. Investigating the cellular responses of osteosarcoma to cisplatin by confocal Raman microspectroscopy. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 226:112366. [PMID: 34826719 DOI: 10.1016/j.jphotobiol.2021.112366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/03/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
Confocal Raman Microspectroscopy (CRM) was employed to clarify the cellular response of cisplatin in osteosarcoma (OS) cells with different dosages and incubation times. The K7M2 mouse osteosarcoma cells were treated by cisplatin in 0 μM (UT group), 20 μM (20 T group), and 40 μM (40 T group) doses for 24-h (24H group) and 48-h (48H group), respectively. Raman spectroscopy was utilized to analyze the drug induced variations of intracellular biochemical components in osteosarcoma cells. The spectral results shows that the main changes in its biochemical composition come from nucleic acids. By adopting three different kernel functions (linear, polynomial, and Gaussian radial basis function (RBF)), principal component analysis combined with support vector machine models (PCA-SVM) was built to address the spectral variations among all investigated groups. Meanwhile, multivariate curve resolution alternating least squares (MCR-ALS) was further utilized to discuss on the chemical interpretation on the acquired spectral results. Moreover, Raman spectral images, which is reconstructed by K-means cluster analysis (KCA) with point-scanned hyperspectral dataset, was applied to illustrate the drug induced compositional and morphological variations in each subcellular region. The achieved results not only prove the application potential of Raman based analytical technique in non-labeled intracellular studies, but also illustrate the detailed compositional and structural information of cisplatin induced OS cell responses from the perspective of multivariate analysis and imaging of Raman spectroscopy.
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Affiliation(s)
- Haifeng Wang
- State Key Laboratory of Photon-Technology in Western China Energy, Institute of Photonics and Photon-Technology, Northwest University, Xi'an, Shaanxi 710127, China
| | - Jing Li
- Department of Orthopedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China
| | - Jie Qin
- Department of Orthopedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China.
| | - Jie Li
- State Key Laboratory of Photon-Technology in Western China Energy, Institute of Photonics and Photon-Technology, Northwest University, Xi'an, Shaanxi 710127, China
| | - Yishen Chen
- State Key Laboratory of Photon-Technology in Western China Energy, Institute of Photonics and Photon-Technology, Northwest University, Xi'an, Shaanxi 710127, China
| | - Dongliang Song
- State Key Laboratory of Photon-Technology in Western China Energy, Institute of Photonics and Photon-Technology, Northwest University, Xi'an, Shaanxi 710127, China
| | - Haishan Zeng
- Imaging Unit - Integrative Oncology Department, BC Cancer Research Center, Vancouver, BC, V5Z1L3, Canada
| | - Shuang Wang
- State Key Laboratory of Photon-Technology in Western China Energy, Institute of Photonics and Photon-Technology, Northwest University, Xi'an, Shaanxi 710127, China.
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16
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Draf C, Wyrick T, Chavez E, Pak K, Kurabi A, Leichtle A, Dazert S, Ryan AF. A Screen of Autophagy Compounds Implicates the Proteasome in Mammalian Aminoglycoside-Induced Hair Cell Damage. Front Cell Dev Biol 2021; 9:762751. [PMID: 34765606 PMCID: PMC8576371 DOI: 10.3389/fcell.2021.762751] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 10/05/2021] [Indexed: 12/30/2022] Open
Abstract
Introduction: Autophagy is a degradative pathway to safely break down and recycle dysfunctional cellular components. There is prior evidence of autophagy participation during hair cell (HC) damage. Our goal was to screen compounds targeting different aspects of autophagy for their effects on HC loss due to an ototoxic aminoglycoside, gentamicin (GM). Methods: The SELLECKChem autophagy compound library, consisting of 154 compounds with defined autophagy inducing or inhibitory activity, was used for targeted screening in vitro model of ototoxicity. Organ of Corti from postnatal days 3–5 pou4f3/GFP transgenic mice (HCs express green fluorescent protein) were utilized. The organs were micro-dissected, and basal and middle turns divided into micro-explants individually placed into the single wells of a 96-well plate. Samples were treated with 200 μM of GM plus three dosages of tested compound and cultured for 72 h. Negative controls were treated with media only; positive ototoxicity controls were treated with GM only. Results: The majority of the library compounds had no effect on GM-induced HC loss. However, 18 compounds exhibited a significant, protective effect, two compounds were protective at low dosage but showed enhanced GM toxicity at higher doses and one compound was toxic to HCs in the absence of GM. Conclusions: This study evaluated many autophagy compounds that have not been tested previously on HCs. The disparate results obtained underscore the complexity of autophagy events that can influence HC responses to aminoglycosides, but also implicate the proteosome as an important damage mechanism. The screening results can serve as basis for further studies with protective compounds as potential drug targets.
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Affiliation(s)
- Clara Draf
- Department of Surgery/Otolaryngology, University of California, San Diego, San Diego, CA, United States.,Department of Otolaryngology, St. Elisabeth-Hospital, Ruhr University Bochum, Bochum, Germany
| | - Taylor Wyrick
- Department of Biology, University of California, San Diego, San Diego, CA, United States
| | - Eduardo Chavez
- Department of Surgery/Otolaryngology, University of California, San Diego, San Diego, CA, United States
| | - Kwang Pak
- Department of Surgery/Otolaryngology, University of California, San Diego, San Diego, CA, United States
| | - Arwa Kurabi
- Department of Surgery/Otolaryngology, University of California, San Diego, San Diego, CA, United States
| | - Anke Leichtle
- Department of Otolaryngology, University Medical Center Schleswig-Holstein, Lübeck, Germany
| | - Stefan Dazert
- Department of Otolaryngology, St. Elisabeth-Hospital, Ruhr University Bochum, Bochum, Germany
| | - Allen F Ryan
- Department of Surgery/Otolaryngology, University of California, San Diego, San Diego, CA, United States.,Department of Neurosciences, University of California, San Diego, San Diego, CA, United States.,VA San Diego Healthcare System, San Diego, CA, United States
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17
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Cortada M, Levano S, Bodmer D. mTOR Signaling in the Inner Ear as Potential Target to Treat Hearing Loss. Int J Mol Sci 2021; 22:ijms22126368. [PMID: 34198685 PMCID: PMC8232255 DOI: 10.3390/ijms22126368] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 12/14/2022] Open
Abstract
Hearing loss affects many people worldwide and occurs often as a result of age, ototoxic drugs and/or excessive noise exposure. With a growing number of elderly people, the number of people suffering from hearing loss will also increase in the future. Despite the high number of affected people, for most patients there is no curative therapy for hearing loss and hearing aids or cochlea implants remain the only option. Important treatment approaches for hearing loss include the development of regenerative therapies or the inhibition of cell death/promotion of cell survival pathways. The mammalian target of rapamycin (mTOR) pathway is a central regulator of cell growth, is involved in cell survival, and has been shown to be implicated in many age-related diseases. In the inner ear, mTOR signaling has also started to gain attention recently. In this review, we will emphasize recent discoveries of mTOR signaling in the inner ear and discuss implications for possible treatments for hearing restoration.
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Affiliation(s)
- Maurizio Cortada
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland; (M.C.); (S.L.)
| | - Soledad Levano
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland; (M.C.); (S.L.)
| | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland; (M.C.); (S.L.)
- Clinic for Otorhinolaryngology, Head and Neck Surgery, University of Basel Hospital, Petersgraben 4, 4031 Basel, Switzerland
- Correspondence: ; Tel.: +41-61-328-76-03
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18
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Hu Y, Ma X. Icariin Treatment Protects Against Gentamicin-Induced Ototoxicity via Activation of the AMPK-SIRT3 Pathway. Front Pharmacol 2021; 12:620741. [PMID: 33679402 PMCID: PMC7930742 DOI: 10.3389/fphar.2021.620741] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 01/12/2021] [Indexed: 02/03/2023] Open
Abstract
Ototoxicity is a serious health problem that greatly affects millions of people worldwide. This condition is caused by the entry of aminoglycosides into auditory hair cells, subsequently inducing reactive oxygen species (ROS) production and accumulation. Several strategies have been adopted to overcome irreversible ROS-induced hair cell loss in mammals. In recent years, icariin, a major active component of the traditional herb Epimedium, has been widely studied and revealed to have antioxidant, anti-inflammatory, and anti-apoptotic properties. In this study, we found that icariin pretreatment improved the survival rate of gentamicin-treated House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and cochlear explants. Icariin remarkably suppressed HEI-OC1 cell apoptosis and inhibited ROS production in cells. Notably, icariin upregulated PGC-1α (SIRT3 promoter) and SIRT3 expression in HEI-OC1 cells. In addition, SIRT3 inhibition significantly attenuated the anti-apoptotic effect of icariin. We also found that icariin can increase AMPK phosphorylation. Further studies showed that inhibition of SIRT3 activity had no significant effect on AMPK phosphorylation. Furthermore, the AMPK inhibitor compound C significantly suppressed SIRT3 expression, meaning that AMPK, as an upstream molecule, regulates SIRT3 expression. Meanwhile, inhibition of AMPK activity significantly reduced the protective effect of icariin on gentamicin ototoxicity. Based on these results, icariin exerts its protective effect on gentamicin-induced ototoxicity via activation of the AMPK-SIRT3 signaling pathway, thus providing a new strategy for treating ototoxicity caused by aminoglycoside antibiotics.
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Affiliation(s)
- Yue Hu
- Department of Otolaryngology Head and Neck Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xiulan Ma
- Department of Otolaryngology Head and Neck Surgery, Shengjing Hospital of China Medical University, Shenyang, China
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19
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Zhao T, Zheng T, Yu H, Hu BH, Hu B, Ma P, Yang Y, Yang N, Hu J, Cao T, Chen G, Yan B, Peshoff M, Hatzoglou M, Geng R, Li B, Zheng QY. Autophagy impairment as a key feature for acetaminophen-induced ototoxicity. Cell Death Dis 2021; 12:3. [PMID: 33414397 PMCID: PMC7791066 DOI: 10.1038/s41419-020-03328-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023]
Abstract
Macroautophagy/autophagy is a highly conserved self-digestion pathway that plays an important role in cytoprotection under stress conditions. Autophagy is involved in hepatotoxicity induced by acetaminophen (APAP) in experimental animals and in humans. APAP also causes ototoxicity. However, the role of autophagy in APAP-induced auditory hair cell damage is unclear. In the present study, we investigated autophagy mechanisms during APAP-induced cell death in a mouse auditory cell line (HEI-OC1) and mouse cochlear explant culture. We found that the expression of LC3-II protein and autophagic structures was increased in APAP-treated HEI-OC1 cells; however, the degradation of SQSTM1/p62 protein, the yellow puncta of mRFP-GFP-LC3 fluorescence, and the activity of lysosomal enzymes decreased in APAP-treated HEI-OC1 cells. The degradation of p62 protein and the expression of lysosomal enzymes also decreased in APAP-treated mouse cochlear explants. These data indicate that APAP treatment compromises autophagic degradation and causes lysosomal dysfunction. We suggest that lysosomal dysfunction may be directly responsible for APAP-induced autophagy impairment. Treatment with antioxidant N-acetylcysteine (NAC) partially alleviated APAP-induced autophagy impairment and apoptotic cell death, suggesting the involvement of oxidative stress in APAP-induced autophagy impairment. Inhibition of autophagy by knocking down of Atg5 and Atg7 aggravated APAP-induced ER and oxidative stress and increased apoptotic cell death. This study provides a better understanding of the mechanism responsible for APAP ototoxicity, which is important for future exploration of treatment strategies for the prevention of hearing loss caused by ototoxic medications.
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Affiliation(s)
- Tong Zhao
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China
| | - Tihua Zheng
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China
| | - Huining Yu
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China
| | - Bo Hua Hu
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, USA
| | - Bing Hu
- Department of Otolaryngology, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Peng Ma
- Department of Genetics, School of Pharmacy, Binzhou Medical University, Yantai, China
| | - Ying Yang
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China
| | - Naidi Yang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, Nanjing, China
| | - Juan Hu
- Department of Otolaryngology-Head & Neck Surgery, Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, China
| | - Tongtao Cao
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China
| | - Gang Chen
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
| | - Bin Yan
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China
| | - Melina Peshoff
- Department of Otolaryngology, Case Western Reserve University, Cleveland, OH, USA
| | - Maria Hatzoglou
- Department of Genetics, Case Western Reserve University, Cleveland, OH, USA
| | - Ruishuang Geng
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China.
| | - Bo Li
- Hearing and Speech Rehabilitation Institute, College of Special Education, Binzhou Medical University, Yantai, China.
| | - Qing Yin Zheng
- Department of Otolaryngology, Case Western Reserve University, Cleveland, OH, USA
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20
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Does Calcium Dobesilate Have Therapeutic Effect on Gentamicin-induced Cochlear Nerve Ototoxicity? An Experimental Study. Otol Neurotol 2020; 41:e1185-e1192. [PMID: 32976341 DOI: 10.1097/mao.0000000000002820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS The ototoxic effects of aminoglycosides are well known. Gentamicin carries a substantial risk of hearing loss. Gentamicin is widely used to combat life-threatening infections, despite its ototoxic effects. Calcium dobesilate is a pharmacologically active agent used to treat many disorders due to its vasoprotective and antioxidant effects. We investigated the therapeutic role of calcium dobesilate against gentamicin-induced cochlear nerve ototoxicity in an animal model. METHODS Thirty-two Sprague Dawley rats were divided into four groups: Gentamicin, Gentamicin + Calcium Dobesilate, Calcium Dobesilate, and Control. Preoperative and postoperative hearing thresholds were determined using auditory brainstem response thresholds with click and 16-kHz tone-burst stimuli. Histological analysis of the tympanic bulla specimens was performed under light and transmission electron microscopy. The histological findings were subjected to semiquantitative grading, of which the results were compared between the groups. RESULTS Gentamicin + Calcium Dobesilate group had, on average, 27 dB better click-evoked hearing than Gentamicin group (p < 0.01), whereas the difference was not significant with 16-kHz tone-burst stimuli (p > 0.01). Histologically examining the Control and Calcium Dobesilate groups revealed normal ultrastructural appearances. The Gentamicin group showed the most severe histological alterations including myelin destruction, total axonal degeneration, and edema. The histological evidence of damage was significantly reduced in the Gentamicin + Calcium Dobesilate group compared with the Gentamicin group. CONCLUSION Adding oral calcium dobesilate to systemic gentamicin was demonstrated to exert beneficial effects on click-evoked hearing thresholds, as supported by the histological findings.
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Hosseinzadeh A, Kamrava SK, Moore BCJ, Reiter RJ, Ghaznavi H, Kamali M, Mehrzadi S. Molecular Aspects of Melatonin Treatment in Tinnitus: A Review. Curr Drug Targets 2020; 20:1112-1128. [PMID: 30892162 DOI: 10.2174/1389450120666190319162147] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 03/09/2019] [Accepted: 03/13/2019] [Indexed: 12/21/2022]
Abstract
Tinnitus is a hearing disorder characterized by the perception of sound without external acoustic stimuli, which is caused by damage to the auditory system in response to excessive levels of noise, ototoxic agents and aging. Neural plasticity, oxidative/nitrosative stress and apoptosis play important roles in the pathogenesis of tinnitus. The expression of neural plasticity related to excessive glutamatergic neurotransmission leads to generation of abnormal sound in one's ears or head. Furthermore, hyperactivation and over-expression of NMDA receptors in response to excessive release of glutamate contribute to the calcium overload in the primary auditory neurons and subsequent cytotoxicity. Reactive oxygen/nitrogen species are endogenously produced by different type of cochlear cells under pathological conditions, which cause direct damage to the intracellular components and apoptotic cell death. Cochlear hair-cell death contributes to the progressive deafferentation of auditory neurons, which consequently leads to the aberrant activity in several parts of the auditory pathway. Therefore, targeting neural plasticity, oxidative/nitrosative stress, apoptosis and autophagy may ameliorate tinnitus. Melatonin is an endogenously produced indoleamine synchronizing circadian and circannual rhythms. Based on laboratory studies indicating the protective effect of melatonin against cochlear damage induced by acoustic trauma and ototoxic agents, and also clinical studies reporting the ability of melatonin to minimize the severity of tinnitus, melatonin is suggested to be a treatment option for the patient with tinnitus. Herein, we describe the ameliorative effect of melatonin on tinnitus, focusing on neural plasticity, oxidative/nitrosative stress, apoptotsis and autophagy.
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Affiliation(s)
- Azam Hosseinzadeh
- Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Seyed Kamran Kamrava
- ENT and Head & Neck Research Center, Hazrate Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Brian C J Moore
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Russel J Reiter
- Department of Cellular and Structural Biology, The University of Texas Health Science Center, San Antonio, TX, United States
| | - Habib Ghaznavi
- Department of Pharmacology, School of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Mahboobeh Kamali
- Health Promotion Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Saeed Mehrzadi
- Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran
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22
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Otoprotective Effect of 2,3,4',5-Tetrahydroxystilbene-2- O-β-d-Glucoside on Gentamicin-Induced Apoptosis in Mouse Cochlear UB/OC-2 Cells. Molecules 2020; 25:molecules25133070. [PMID: 32640539 PMCID: PMC7412181 DOI: 10.3390/molecules25133070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 02/06/2023] Open
Abstract
Excessive levels of reactive oxygen species (ROS) lead to mitochondrial damage and apoptotic cell death in gentamicin-induced ototoxicity. 2,3,4',5-Tetrahydroxystilbene-2-O-β-d-glucoside (THSG), a bioactive constituent, isolated from Polygonum multiflorum Thunb., exhibits numerous biological benefits in treating aging-related diseases by suppressing oxidative damage. However, its protective effect on gentamicin-induced ototoxicity remains unexplored. Therefore, here, we aimed to investigate the otoprotective effect of THSG on gentamicin-induced apoptosis in mouse cochlear UB/OC-2 cells. We evaluated the effect of gentamicin and THSG on the ROS level, superoxide dismutase (SOD) activity, mitochondrial membrane potential, nuclear condensation, and lactate dehydrogenase (LDH) release, and the expression of apoptosis-related proteins was assessed to understand the molecular mechanisms underlying its preventive effects. The findings demonstrated that gentamicin increased ROS generation, LDH release, and promoted apoptotic cell death in UB/OC-2 cells. However, THSG treatment reversed these effects by suppressing ROS production and downregulating the mitochondrial-dependent apoptotic pathway. Additionally, it increased the SOD activity, decreased the expression of apoptosis-related proteins, alleviated the levels of the apoptotic cells, and impaired cytotoxicity. To the best of our knowledge, this is the first study to demonstrate that THSG could be a potential therapeutic option to attenuate gentamicin-induced ototoxicity.
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Saegusa C, Hosoya M, Nishiyama T, Saeki T, Fujimoto C, Okano H, Fujioka M, Ogawa K. Low-dose rapamycin-induced autophagy in cochlear outer sulcus cells. Laryngoscope Investig Otolaryngol 2020; 5:520-528. [PMID: 32596496 PMCID: PMC7314457 DOI: 10.1002/lio2.392] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/02/2020] [Accepted: 04/26/2020] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVES Autophagy is an intracellular housekeeping process that degrades cytoplasmic organelles, damaged molecules, and abnormal proteins or pathogens and is essential for normal hearing. Recent studies revealed the essential roles of autophagy in hearing and balance. The aim of this study was to evaluate the activation state of rapamycin-induced autophagy in cochlear outer sulcus cells (OSCs). METHODS We used autophagy reporter transgenic mice expressing the green fluorescent protein-microtubule-associated protein light chain 3 (GFP-LC3) fusion protein and counted GFP-LC3 puncta in cochlear OSCs to evaluate the activation state of autophagy after oral administration of rapamycin. RESULTS We observed basal level GFP-LC3 expression and an increase in the number of GFP-LC3 puncta in cochlear OSCs by oral administration of rapamycin. This increase was detected when the daily rapamycin intake was as low as 0.025 mg/kg, and it was dose dependent. The increased number of puncta was more at the basal turn than the apical turn. CONCLUSION Oral intake of low-dose rapamycin activates autophagy in cochlear OSCs. LEVEL OF EVIDENCE NA.
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Affiliation(s)
- Chika Saegusa
- Department of Otorhinolaryngology, Head and Neck SurgeryKeio University School of MedicineTokyoJapan
| | - Makoto Hosoya
- Department of Otorhinolaryngology, Head and Neck SurgeryKeio University School of MedicineTokyoJapan
| | - Takanori Nishiyama
- Department of Otorhinolaryngology, Head and Neck SurgeryKeio University School of MedicineTokyoJapan
| | - Tsubasa Saeki
- Department of PhysiologyKeio University School of MedicineTokyoJapan
| | - Chisato Fujimoto
- Department of Otolaryngology and Head and Neck SurgeryGraduate School of Medicine, University of TokyoTokyoJapan
| | - Hideyuki Okano
- Department of PhysiologyKeio University School of MedicineTokyoJapan
| | - Masato Fujioka
- Department of Otorhinolaryngology, Head and Neck SurgeryKeio University School of MedicineTokyoJapan
| | - Kaoru Ogawa
- Department of Otorhinolaryngology, Head and Neck SurgeryKeio University School of MedicineTokyoJapan
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Protective Mechanisms of Avocado Oil Extract Against Ototoxicity. Nutrients 2020; 12:nu12040947. [PMID: 32235401 PMCID: PMC7230542 DOI: 10.3390/nu12040947] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 02/07/2023] Open
Abstract
Despite the excellent antimicrobial activity of aminoglycoside antibiotics, permanent inner ear damage associated with the use of these drugs has resulted in the need to develop strategies to address the ototoxic risk given their widespread use. In a previous study, we showed that avocado oil protects ear hair cells from damage caused by neomycin. However, the detailed mechanism by which this protection occurs is still unclear. Here, we investigated the auditory cell-protective mechanism of enhanced functional avocado oil extract (DKB122). RNA sequencing followed by pathway analysis revealed that DKB122 has the potential to enhance the expression of detoxification and antioxidant genes associated with glutathione metabolism (Hmox4, Gsta4, Mgst1, and Abcc3) in HEI-OC1 cells. Additionally, DKB122 effectively decreased ROS levels, resulting in the inhibition of apoptosis in HEI-OC1 cells. The expression of the inflammatory genes that encode chemokines and interleukins was also downregulated by DKB122 treatment. Consistent with these results, DKB122 significantly inhibited p65 nuclear migration induced by TNF-α or LPS in HEI-OC1 cells and THP-1 cells and the expression of inflammatory chemokine and interleukin genes induced by TNF-α was significantly reduced. Moreover, DKB122 treatment increased LC3-II and decreased p62 in HEI-OC1 cells, suggesting that DKB122 increases autophagic flux. These results suggest that DKB122 has otoprotective effects attributable to its antioxidant activity, induction of antioxidant gene expression, anti-inflammatory activity, and autophagy activation.
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Systemic Fluorescent Gentamicin Enters Neonatal Mouse Hair Cells Predominantly Through Sensory Mechanoelectrical Transduction Channels. J Assoc Res Otolaryngol 2020; 21:137-149. [PMID: 32152768 DOI: 10.1007/s10162-020-00746-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 02/10/2020] [Indexed: 01/25/2023] Open
Abstract
Systemically administered aminoglycoside antibiotics can enter inner ear hair cells and trigger apoptosis. However, the in vivo route(s) by which aminoglycoside antibiotics enter hair cells remains controversial. Aminoglycosides can enter mouse hair cells by endocytosis or by permeation through transmembrane ion channels such as sensory mechanoelectrical transduction (MET) channels, transient receptor potential (TRP) channels, P2X channels, Piezo2-containing ion channels, or a combination of these routes. Transmembrane channel-like 1 (TMC1) and TMC2 are essential for sensory MET and appear to be the pore-forming components of sensory MET channels. The present study tested the hypothesis that systemic fluorescent gentamicin enters mouse hair cells predominantly through sensory MET channels. We employed Tmc1Δ, Tmc2Δ, and Tmc1::mCherry mice. In Tmc1::mCherry mice, the transgene was integrated on the X chromosome, resulting in mosaic expression of TMC1-mCherry in the hair cells of female heterozygous mice. After systemic administration of gentamicin-conjugated Texas Red (GTTR) into Tmc1Δ;Tmc2Δ mice and wild-type mice at postnatal day 4 (P4), robust GTTR fluorescence was detected in wild-type hair cells, whereas little or no GTTR fluorescence was detected in Tmc1Δ;Tmc2Δ hair cells. When GTTR was injected into developing mice at P0, P2, P4, or P6, the GTTR fluorescent intensity gradually increased from P0 to P4 in wild-type hair cells, whereas the intensity was stably low from P0 through P6 in Tmc1Δ;Tmc2Δ hair cells. The increase in the GTTR intensity coincided with the spatio-temporal onset of sensory MET in wild-type hair cells. In Tmc1::mCherry cochleae, only hair cells that showed a significant uptake of systemic GTTR took up FM1-43. Transmission electron microscopy could detect no disruption of normal endocytosis at the apical surface of Tmc1Δ;Tmc2Δ hair cells in vitro. These results provide substantial novel evidence that in vivo gentamicin enters neonatal mouse hair cells predominantly through sensory MET channels and not via endocytosis.
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Low WK, Teng SW, Tan MGK. Synergistic Ototoxicity of Gentamicin and Low-Dose Irradiation: Molecular Basis and Clinical Significance. Audiol Neurootol 2019; 25:111-119. [PMID: 31838466 DOI: 10.1159/000503133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 09/03/2019] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Inner ear structures may be included in the radiation fields when irradiation is used to treat patients with head and neck cancers. These patients may also have concurrent infections that require gentamicin treatment. Radiation and gentamicin are both potentially ototoxic, and their combined use has been shown to result in synergistic ototoxicity in animals. OBJECTIVE We aimed to confirm the synergistic ototoxicity of combined gentamicin and low-dose irradiation treatment and identify the underlying molecular mechanisms using an in vitro model. METHOD We compared the ototoxic effects of gentamicin, low-dose irradiation, and their combination in the OC-k3 mouse cochlear cell line using cell viability assay, live/dead stain, apoptosis detection assay, oxidative stress detection, and studied the molecular mechanisms involved using immunoblot analysis. RESULTS Combined treatment led to prolonged oxidative stress, reduced cell viability, and synergistic apoptosis. Gentamicin induced the concurrent accumulation of LC3b-II and SQSTM1/p62, suggesting an impairment of autophagic flux. Low-dose irradiation induced transient p53 phosphorylation and persistent Akt phosphorylation in response to DNA damage. In combined treatment, gentamicin attenuated irradiation-induced Akt activation. CONCLUSIONS Besides increased oxidative stress, synergistic apoptosis observed in combined treatment could be attributed to gentamicin-induced perturbation of autophagic flux and attenuation of Akt phosphorylation, which led to an impairment of radiation-induced DNA repair response.
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Affiliation(s)
- Wong Kein Low
- Department of Otolaryngology, Singapore General Hospital, Singapore, Singapore, .,Duke-NUS Graduate Medical School, Singapore, Singapore, .,Novena Ent-Head and Neck Surgery Specialist Centre, Mount Elizabeth Novena Medical Centre, Singapore, Singapore,
| | - Siaw Wei Teng
- Department of Otolaryngology, Singapore General Hospital, Singapore, Singapore
| | - Michelle G K Tan
- Departments of Clinical Translational Research, Singapore General Hospital, Singapore, Singapore
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A Tmc1 mutation reduces calcium permeability and expression of mechanoelectrical transduction channels in cochlear hair cells. Proc Natl Acad Sci U S A 2019; 116:20743-20749. [PMID: 31548403 PMCID: PMC6789967 DOI: 10.1073/pnas.1908058116] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cochlear hair cells transduce sound into electrical signals by activation of mechanically sensitive ion channels thought to be formed by TMC1. We generated a single aspartate/asparagine substitution in mouse TMC1 which is homologous to a human genetic deafness mutation. The main consequence was reduction in the Ca2+ permeability of the mechanically sensitive channel with little change in its unitary conductance. Nevertheless, there was a much reduced expression of the ion channel, which led within 4 wk to death of the outer hair cells culminating in deafness. The mouse mutant accounts for the human deafness and implies that TMC1, in addition to forming the mechanically sensitive ion channel, regulates its own expression. Mechanoelectrical transducer (MET) currents were recorded from cochlear hair cells in mice with mutations of transmembrane channel-like protein TMC1 to study the effects on MET channel properties. We characterized a Tmc1 mouse with a single-amino-acid mutation (D569N), homologous to a dominant human deafness mutation. Measurements were made in both Tmc2 wild-type and Tmc2 knockout mice. By 30 d, Tmc1 pD569N heterozygote mice were profoundly deaf, and there was substantial loss of outer hair cells (OHCs). MET current in OHCs of Tmc1 pD569N mutants developed over the first neonatal week to attain a maximum amplitude one-third the size of that in Tmc1 wild-type mice, similar at apex and base, and lacking the tonotopic size gradient seen in wild type. The MET-channel Ca2+ permeability was reduced 3-fold in Tmc1 pD569N homozygotes, intermediate deficits being seen in heterozygotes. Reduced Ca2+ permeability resembled that of the Tmc1 pM412K Beethoven mutant, a previously studied semidominant mouse mutation. The MET channel unitary conductance, assayed by single-channel recordings and by measurements of current noise, was unaffected in mutant apical OHCs. We show that, in contrast to the Tmc1 M412K mutant, there was reduced expression of the TMC1 D569N channel at the transduction site assessed by immunolabeling, despite the persistence of tip links. The reduction in MET channel Ca2+ permeability seen in both mutants may be the proximate cause of hair-cell apoptosis, but changes in bundle shape and protein expression in Tmc1 D569N suggest another role for TMC1 apart from forming the channel.
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Choi MJ, Kang H, Lee YY, Choo OS, Jang JH, Park SH, Moon JS, Choi SJ, Choung YH. Cisplatin-Induced Ototoxicity in Rats Is Driven by RIP3-Dependent Necroptosis. Cells 2019; 8:E409. [PMID: 31052605 PMCID: PMC6562419 DOI: 10.3390/cells8050409] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/25/2019] [Accepted: 04/30/2019] [Indexed: 12/22/2022] Open
Abstract
Cisplatin-induced early-onset ototoxicity is linked to hearing loss. The mechanism by which cisplatin causes ototoxicity remains unclear. The purpose of this study was to identify the involvement of receptor-interacting protein kinase (RIP)3-dependent necroptosis in cisplatin-induced ototoxicity in vitro and in vivo. Sprague-Dawley rats (SD, 8 week) were treated via intraperitoneal (i.p.) injection with cisplatin (16 mg/kg for 1 day), and their hearing thresholds were measured by the auditory brainstem response (ABR) method. Hematoxylin and eosin (H & E) staining, immunohistochemistry, and western blots were performed to determine the effect of cisplatin-induced ototoxicity on cochlear morphology. Inhibitor experiments with necrostatin 1 (Nec-1) and Z-VAD were also performed in HEI-OC1 cell line. H&E stains revealed that the necroptotic changes were increased in the organ of Corti (OC) and spiral ganglion neurons (SGNs). Moreover, immunohistochemistry and western blot analysis showed that cisplatin treatment increased the protein levels of RIP3 in both OCs and SGNs. The treatment of Nec-1, a selective RIP1 inhibitor, resulted in markedly suppression of cisplatin-induced cell death in HEI-OC1 cells, whereas Z-VAD treatment did not change the cisplatin-induced cell death. Our results suggest that RIP3-dependent necroptosis was substantial in cisplatin-induced ototoxicity; inner cochlear regions, the OCs, and SGNs were especially sensitive to necroptosis.
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Affiliation(s)
- Mi-Jin Choi
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Hyunsook Kang
- Department of Otolaryngology-Head and Neck Surgery, Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan 31151, Korea.
| | - Yun Yeong Lee
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Oak-Sung Choo
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Jeong Hun Jang
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Sung-Hee Park
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Jong-Seok Moon
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan 31151, Korea.
| | - Seong Jun Choi
- Department of Otolaryngology-Head and Neck Surgery, Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan 31151, Korea.
| | - Yun-Hoon Choung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
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Kim YJ, Kim K, Lee YY, Choo OS, Jang JH, Choung YH. Downregulated UCHL1 Accelerates Gentamicin-Induced Auditory Cell Death via Autophagy. Mol Neurobiol 2019; 56:7433-7447. [PMID: 31041655 DOI: 10.1007/s12035-019-1598-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 04/02/2019] [Indexed: 01/02/2023]
Abstract
The clinical use of aminoglycoside antibiotics is partly limited by their ototoxicity. The pathogenesis of aminoglycoside-induced ototoxicity still remains unknown. Here, RNA-sequencing was conducted to identify differentially expressed genes in rat cochlear organotypic cultures treated with gentamicin (GM), and 232 and 43 genes were commonly up- and downregulated, respectively, at day 1 and 2 after exposure. Ubiquitin carboxyl-terminal hydrolase isozyme L1 (Uchl1) was one of the downregulated genes whose expression was prominent in spiral ganglion cells (SGCs), lateral walls, as well as efferent nerve terminal and nerve fibers. We further investigated if a deficit of Uchl1 in organotypic cochlea and the House Ear Institute-Organ of Corti 1 (HEI-OC1) cells accelerates ototoxicity. We found that a deficit in Uchl1 accelerated GM-induced ototoxicity by showing a decreased number of SGCs and nerve fibers in organotypic cochlear cultures and HEI-OC1 cells. Furthermore, Uchl1-depleted HEI-OC1 cells revealed an increased number of autophagosomes accompanied by decreased lysosomal fusion. These data indicate that the downregulation of Uchl1 following GM treatment is deleterious to auditory cell survival, which results from the impaired autophagic flux. Our results provide evidence that UCHL1-dependent autophagic flux may have a potential as an otoprotective target for the treatment of GM-induced auditory cell death.
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Affiliation(s)
- Yeon Ju Kim
- Department of Otolaryngology, Ajou University School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea
| | - Kyung Kim
- Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yun Yeong Lee
- Department of Otolaryngology, Ajou University School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea
| | - Oak-Sung Choo
- Department of Otolaryngology, Ajou University School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea.,Department of Medical Sciences, Ajou University Graduate School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea
| | - Jeong Hun Jang
- Department of Otolaryngology, Ajou University School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea
| | - Yun-Hoon Choung
- Department of Otolaryngology, Ajou University School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea. .,Department of Medical Sciences, Ajou University Graduate School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea. .,BK21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, San 5 Woncheon-dong, Yeongtong-gu, Suwon, 443-721, Republic of Korea.
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30
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Zhang X, Yu J. Baicalin attenuates gentamicin-induced cochlear hair cell ototoxicity. J Appl Toxicol 2019; 39:1208-1214. [PMID: 31021006 DOI: 10.1002/jat.3806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/18/2018] [Accepted: 11/29/2018] [Indexed: 01/13/2023]
Abstract
Gentamicin can lead to cochlear hair cells associated ototoxicity by inducing apoptosis and oxidative stress, which can be alleviated by baicalin, one flavonoid extracted from the root of Scutellaria baicalensis. The role of baicalin in protecting gentamicin-induced hearing loss is unclear. Interference with oxidative stress was investigated in this study using House Ear Institute-Organ of Corti1 (HEI-OC1) cells, which were simultaneously treated with baicalin (0-400 μm) and gentamicin (0.2 or 1 mm). MTT was used to assay cell viability and apoptosis was detected with Annexin V-fluorescein isothiocyanate staining. The production of reactive oxygen species was indicated by 2,7-dichlorofluorescein diacetate fluorescence intensity and mitochondrial depolarization was assayed by JC1-mitochondrial membrane potential assay. Poly(ADP-ribose) polymerase (PARP), cleaved-caspase 3 and cleaved-PARP expression were analyzed with western blot. Baicalin improved the viability of HEI-OC1 cells and significantly reduced the oxidative stress and mitochondrial depolarization compared with the gentamicin treatment group. Gentamicin treatment increased the activation of PARP and caspase-3, while such an increase could be downregulated by baicalin. Baicalin attenuates gentamicin-induced cochlear hair cells ototoxicity, and such inhibition may be mediated by the regulation of reactive oxygen species production, mitochondrial depolarization, and caspase-3 and PARP activation.
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Affiliation(s)
- Xianfen Zhang
- Department of Otolaryngology, Yantaishan Hospital, Shandong, China
| | - Jun Yu
- Department of Otolaryngology, Yantai YEDA Hospital, Shandong, China
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Fu X, Sun X, Zhang L, Jin Y, Chai R, Yang L, Zhang A, Liu X, Bai X, Li J, Wang H, Gao J. Tuberous sclerosis complex-mediated mTORC1 overactivation promotes age-related hearing loss. J Clin Invest 2018; 128:4938-4955. [PMID: 30247156 DOI: 10.1172/jci98058] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 08/08/2018] [Indexed: 12/29/2022] Open
Abstract
The underlying molecular mechanisms of age-related hearing loss (ARHL) in humans and many strains of mice have not been fully characterized. This common age-related disorder is assumed to be closely associated with oxidative stress. Here, we demonstrate that mTORC1 signaling is highly and specifically activated in the cochlear neurosensory epithelium (NSE) in aging mice, and rapamycin injection prevents ARHL. To further examine the specific role of mTORC1 signaling in ARHL, we generated murine models with NSE-specific deletions of Raptor or Tsc1, regulators of mTORC1 signaling. Raptor-cKO mice developed hearing loss considerably more slowly than WT littermates. Conversely, Tsc1 loss led to the early-onset death of cochlear hair cells and consequently accelerated hearing loss. Tsc1-cKO cochleae showed features of oxidative stress and impaired antioxidant defenses. Treatment with rapamycin and the antioxidant N-acetylcysteine rescued Tsc1-cKO hair cells from injury in vivo. In addition, we identified the peroxisome as the initial signaling organelle involved in the regulation of mTORC1 signaling in cochlear hair cells. In summary, our findings identify overactive mTORC1 signaling as one of the critical causes of ARHL and suggest that reduction of mTORC1 activity in cochlear hair cells may be a potential strategy to prevent ARHL.
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Affiliation(s)
- Xiaolong Fu
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Xiaoyang Sun
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Linqing Zhang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Yecheng Jin
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Renjie Chai
- Key Laboratory for Development Genes and Human Disease, Southeast University, Nanjing, China
| | - Lili Yang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Aizhen Zhang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China.,Department of Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Xiangguo Liu
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Xiaochun Bai
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jianfeng Li
- Department of Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Haibo Wang
- Department of Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Jiangang Gao
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
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Setz C, Benischke AS, Pinho Ferreira Bento AC, Brand Y, Levano S, Paech F, Leitmeyer K, Bodmer D. Induction of mitophagy in the HEI-OC1 auditory cell line and activation of the Atg12/LC3 pathway in the organ of Corti. Hear Res 2018; 361:52-65. [PMID: 29352609 DOI: 10.1016/j.heares.2018.01.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 12/29/2017] [Accepted: 01/06/2018] [Indexed: 01/12/2023]
Abstract
Autophagy is a highly evolutionary conserved quality control defense mechanism within cells, which has also been implicated in cell death processes. In the mammalian inner ear, autophagy has been shown to play a role during early morphogenesis as well as in adult cochlear hair cells exposed to ototoxic insults. Mitophagy, a selective autophagic cell process targeting mitochondria, hasn't been studied in the inner ear so far. On this work, we searched for molecular indicators of mitophagy within House Ear Institute-Organ of Corti-1 (HEI-OC1) cells as well as in the organ of Corti (OC). We first tested for the expression of Pink1/Park2 mRNA in 5-day-old C57BL/6 mice's cochleae using RT-PCR. We focused on the induction of mitophagy in HEI-OC1 cells as well as in the OC and investigated a possible mitophagic potential of the aminoglycoside agent gentamicin. The induction of mitophagy in HEI-OC1 cells was detected by objectivizing the translocation of fluorescence-tagged LC3 to mitochondria using confocal microscopy after a 6-h incubation with a well-described mitochondrial uncoupler and mitophagy-inducing agent: carbonyl cyanide m-chlorophenyl hydrazone (CCCP). Incubation with gentamicin generated no mitochondrial translocation of LC3. Protein levels of COXIV, Atg5/12 and LC3 were evaluated by an immunoblot analysis after a 24-h CCCP treatment as well as gentamicin. We demonstrated mitophagy after CCCP exposure in HEI-OC1 cells by showing a downregulation of COXIV. A downregulation of COXIV could also be visualized in the OC after CCCP. A significant oxygen consumption rate (OCR) changed in cells treated with CCCP as well as significant morphological changes of mitochondria by electron microscopy (EM) strengthen this assumption. Gentamicin exposure generated no impact on OCR or mitochondrial morphological changes by EM. Finally, we demonstrated changes in the expression of Atg12 and LC3 proteins in both the OC and HEI-OC1 cells after CCCP exposure but not after gentamicin. Our data indicate that gentamicin had no impact in the activation of mitophagy-neither in the HEI-OC1 cell line nor in the OC. Therefore, we speculate that mitophagic-independent mechanisms may underly aminoglycoside ototoxicity.
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Affiliation(s)
- Cristian Setz
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland; Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Anne-Sophie Benischke
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland
| | | | - Yves Brand
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland; Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Soledad Levano
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland
| | - Franziska Paech
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland; Department of Clinical Pharmacology and Toxicology, University Hospital Basel, Hebelstrasse 2, 4031, Basel, Switzerland
| | - Katharina Leitmeyer
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland; Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland; Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
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Nicholas BD, Francis S, Wagner EL, Zhang S, Shin JB. Protein Synthesis Inhibition and Activation of the c-Jun N-Terminal Kinase Are Potential Contributors to Cisplatin Ototoxicity. Front Cell Neurosci 2017; 11:303. [PMID: 29033791 PMCID: PMC5627031 DOI: 10.3389/fncel.2017.00303] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/12/2017] [Indexed: 11/29/2022] Open
Abstract
Cisplatin has been regarded as an effective and versatile chemotherapeutic agent for nearly 40 years. Though the associated dose-dependent ototoxicity is known, the cellular mechanisms by which cochleovestibular hair cell death occur are not well understood. We have previously shown that aminoglycoside ototoxicity is mediated in part by cytosolic protein synthesis inhibition. Despite a lack of molecular similarity, aminoglycosides were shown to elicit similar stress pathways to cisplatin. We therefore reasoned that there may be some role of protein synthesis inhibition in cisplatin ototoxicity. Employing a modification of the bioorthogonal noncanonical amino acid tagging (BONCAT) method, we evaluated the effects of cisplatin on cellular protein synthesis. We show that cisplatin inhibits cellular protein synthesis in organ of Corti explant cultures. Similar to what was found after gentamicin exposure, cisplatin activates both the c-Jun N-terminal kinase (JNK) and mammalian target of rapamycin (mTOR) pathways. In contrast to aminoglycosides, cisplatin also inhibits protein synthesis in all cochlear cell types. We further demonstrate that the multikinase inhibitor sorafenib completely prevents JNK activation, while providing only moderate hair cell protection. Simultaneous stimulation of cellular protein synthesis by insulin, however, significantly improved hair cell survival in culture. The presented data provides evidence for a potential role of protein synthesis inhibition in cisplatin-mediated ototoxicity.
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Affiliation(s)
- Brian D Nicholas
- Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Shimon Francis
- Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Elizabeth L Wagner
- Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Sibo Zhang
- Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Jung-Bum Shin
- Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
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Ebnoether E, Ramseier A, Cortada M, Bodmer D, Levano-Huaman S. Sesn2 gene ablation enhances susceptibility to gentamicin-induced hair cell death via modulation of AMPK/mTOR signaling. Cell Death Discov 2017; 3:17024. [PMID: 28580173 PMCID: PMC5447131 DOI: 10.1038/cddiscovery.2017.24] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/04/2017] [Indexed: 12/14/2022] Open
Abstract
The process of gentamicin-induced hair cell damage includes the activation of oxidative stress processes. Sestrins, as stress-responsive proteins, protect cells against oxidative stress. Sestrins, particularly Sestrin-2, suppress excessive reactive oxygen species (ROS) accumulation and inhibit mammalian target of rapamycin complex 1 (mTORC1). Thus, we addressed the role of Sestrin-2 in the regulation of sensory hair cell survival after gentamicin exposure. Here, we show that Sestrins were expressed in the inner ear tissues, and Sestrin-2 immunolocalized in sensory hair cells and spiral ganglion (SG). The expression of Sestrin-2 was unchanged, and later downregulated, in gentamicin-treated explants from wild-type mice in vitro. Compared with wild-type mice, Sestrin-2 knockout mice exhibited significantly greater hair cell loss in gentamicin-treated cochlear explants. Significant downregulation of phosphorylation of AMP-activated protein kinase alpha (AMPKα) and upregulation of the 70-kDa ribosomal protein S6 kinase (p70S6K) were measured in wild-type cochlear explants exposed to gentamicin compared with their untreated controls. Such regulatory effect was not observed between explants from untreated and gentamicin-treated knockout mice. The gentamicin effect on mTOR signaling was rapamycin-sensitive. Thus, our data provide evidence that Sestrin-2 plays an important role in the protection of hair cells against gentamicin, and the mTOR signaling pathway appears to be modulated by gentamicin during hair cell death.
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Affiliation(s)
- Eliane Ebnoether
- Department of Biomedicine, Head and Neck Surgery, University of Basel Hospital, Basel, Switzerland
| | - Alessia Ramseier
- Department of Biomedicine, Head and Neck Surgery, University of Basel Hospital, Basel, Switzerland
| | - Maurizio Cortada
- Department of Biomedicine, Head and Neck Surgery, University of Basel Hospital, Basel, Switzerland
| | - Daniel Bodmer
- Department of Biomedicine, Head and Neck Surgery, University of Basel Hospital, Basel, Switzerland.,Department of Otolaryngology, Head and Neck Surgery, University of Basel Hospital, Basel, Switzerland
| | - Soledad Levano-Huaman
- Department of Biomedicine, Head and Neck Surgery, University of Basel Hospital, Basel, Switzerland
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