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Shibata SB, West MB, Du X, Iwasa Y, Raphael Y, Kopke RD. Gene therapy for hair cell regeneration: Review and new data. Hear Res 2020; 394:107981. [DOI: 10.1016/j.heares.2020.107981] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/19/2020] [Accepted: 04/22/2020] [Indexed: 02/06/2023]
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Autophagy Triggered by Oxidative Stress Appears to Be Mediated by the AKT/mTOR Signaling Pathway in the Liver of Sleep-Deprived Rats. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:6181630. [PMID: 32148653 PMCID: PMC7044486 DOI: 10.1155/2020/6181630] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 10/22/2019] [Accepted: 12/11/2019] [Indexed: 12/22/2022]
Abstract
Sleep deprivation adversely affects the digestive system. Multiple studies have suggested sleep deprivation and oxidative stress are closely related. Autophagy can be triggered by oxidative stress as a self-defense strategy to promote survival. In this study, we investigated the effects of sleep deprivation on liver functions, oxidative stress, and concomitant hepatocyte autophagy, as well as the associated pathways. Enzymatic and nonenzymatic biochemical markers in the serum were used to assess hepatic function and damage. To evaluate the occurrence of autophagy, expression of autophagy-related proteins was tested and autophagosomes were labeled. Additionally, methane dicarboxylic aldehyde (MDA), antioxidant enzymes, and the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway were analyzed using chemical methods and a Western blot. Serum alanine transaminase, aspartate aminotransferase, and alkaline phosphatase increased in sleep-deprived rats. Total protein and albumin abundance was also abnormal. Sleep deprivation induced histopathological changes in the liver. The superoxide dismutase level decreased significantly in the liver of sleep-deprived rats. In contrast, the MDA content increased in the sleep deprivation group. Moreover, the microtubule-associated protein 1 light chain 3 beta (LC3B) II/I ratio and Beclin I content increased considerably in the sleep-deprived rats, while p62 levels decreased. Sleep deprivation apparently inhibited the AKT/mTOR signaling pathway. We conclude that sleep deprivation can induce oxidative stress and ultimately cause liver injury. Autophagy triggered by oxidative stress appears to be mediated by the AKT/mTOR pathway and plays a role in relieving oxidative stress caused by sleep deprivation.
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Walters BJ, Cox BC. Approaches for the study of epigenetic modifications in the inner ear and related tissues. Hear Res 2019; 376:69-85. [PMID: 30679030 DOI: 10.1016/j.heares.2019.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/12/2018] [Accepted: 01/11/2019] [Indexed: 12/12/2022]
Abstract
DNA methylation and histone modifications such as methylation, acetylation, and phosphorylation, are two types of epigenetic modifications that alter gene expression. These additions to DNA regulatory elements or to the tails of histones can be inherited or can also occur de novo. Since epigenetic modifications can have significant effects on various processes at both the cellular and organismal level, there has been a rapid increase in research on this topic throughout all fields of biology in recent years. However, epigenetic research is relativity new for the inner ear field, likely due to the limited number of cells present and their quiescent nature. Here, we provide an overview of methods used to detect DNA methylation and histone modifications with a focus on those that have been validated for use with limited cell numbers and a discussion of the strengths and limitations for each. We also provide examples for how these methods have been used to investigate the epigenetic landscape in the inner ear and related tissues.
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Affiliation(s)
- Bradley J Walters
- Departments of Neurobiology and Anatomical Sciences, and of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - Brandon C Cox
- Departments of Pharmacology and Surgery, Division of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA.
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Burns JC, Stone JS. Development and regeneration of vestibular hair cells in mammals. Semin Cell Dev Biol 2017; 65:96-105. [PMID: 27864084 PMCID: PMC5423856 DOI: 10.1016/j.semcdb.2016.11.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 11/03/2016] [Indexed: 10/20/2022]
Abstract
Vestibular sensation is essential for gaze stabilization, balance, and perception of gravity. The vestibular receptors in mammals, Type I and Type II hair cells, are located in five small organs in the inner ear. Damage to hair cells and their innervating neurons can cause crippling symptoms such as vertigo, visual field oscillation, and imbalance. In adult rodents, some Type II hair cells are regenerated and become re-innervated after damage, presenting opportunities for restoring vestibular function after hair cell damage. This article reviews features of vestibular sensory cells in mammals, including their basic properties, how they develop, and how they are replaced after damage. We discuss molecules that control vestibular hair cell regeneration and highlight areas in which our understanding of development and regeneration needs to be deepened.
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Affiliation(s)
- Joseph C Burns
- Decibel Therapeutics, 215 First St., Suite 430, Cambridge, MA 02142, USA.
| | - Jennifer S Stone
- Department of Otolaryngology/Head and Neck Surgery and The Virginia Merrill Bloedel Hearing Research Center, University of Washington School of Medicine, Box 357923, Seattle, WA 98195-7923, USA.
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Laos M, Sulg M, Herranen A, Anttonen T, Pirvola U. Indispensable role of Mdm2/p53 interaction during the embryonic and postnatal inner ear development. Sci Rep 2017; 7:42216. [PMID: 28181574 PMCID: PMC5299844 DOI: 10.1038/srep42216] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/05/2017] [Indexed: 02/06/2023] Open
Abstract
p53 is a key component of a signaling network that protects cells against various stresses. As excess p53 is detrimental to cells, its levels are tightly controlled by several mechanisms. The E3 ubiquitin ligase Mdm2 is a major negative regulator of p53. The significance of balanced p53 levels in normal tissues, at different stages of lifetime, is poorly understood. We have studied in vivo how the disruption of Mdm2/p53 interaction affects the early-embryonic otic progenitor cells and their descendants, the auditory supporting cells and hair cells. We found that p53 accumulation, as a consequence of Mdm2 abrogation, is lethal to both proliferative progenitors and non-proliferating, differentiating cells. The sensitivity of postmitotic supporting cells to excess p53 decreases along maturation, suggesting that maturation-related mechanisms limit p53′s transcriptional activity towards pro-apoptotic factors. We have also investigated in vitro whether p53 restricts supporting cell’s regenerative capacity. Unlike in several other regenerative cellular models, p53 inactivation did not alter supporting cell’s proliferative quiescence nor transdifferentiation capacity. Altogether, the postmitotic status of developing hair cells and supporting cells does not confer protection against the detrimental effects of p53 upregulation. These findings might be linked to auditory disturbances observed in developmental syndromes with inappropriate p53 upregulation.
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Affiliation(s)
- M Laos
- Division of Physiology and Neuroscience, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
| | - M Sulg
- Division of Physiology and Neuroscience, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
| | - A Herranen
- Division of Physiology and Neuroscience, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
| | - T Anttonen
- Division of Physiology and Neuroscience, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
| | - U Pirvola
- Division of Physiology and Neuroscience, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
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Wu J, Li W, Lin C, Chen Y, Cheng C, Sun S, Tang M, Chai R, Li H. Co-regulation of the Notch and Wnt signaling pathways promotes supporting cell proliferation and hair cell regeneration in mouse utricles. Sci Rep 2016; 6:29418. [PMID: 27435629 PMCID: PMC4951696 DOI: 10.1038/srep29418] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/16/2016] [Indexed: 02/07/2023] Open
Abstract
This work sought to determine the crosstalk between the Notch and Wnt signaling pathways in regulating supporting cell (SC) proliferation and hair cell (HC) regeneration in mouse utricles. We cultured postnatal day (P)3 and P60 mouse utricles, damaged the HCs with gentamicin, and treated the utricles with the γ-secretase inhibitor DAPT to inhibit the Notch pathway and with the Wnt agonist QS11 to active the Wnt pathway. We also used Sox2-CreER, Notch1-flox (exon 1), and Catnb-flox (exon 3) transgenic mice to knock out the Notch pathway and activate the Wnt pathway in Sox2+ SCs. Notch inhibition alone increased SC proliferation and HC number in both undamaged and damaged utricles. Wnt activation alone promoted SC proliferation, but the HC number was not significantly increased. Here we demonstrated the cumulative effects of Notch inhibition and Wnt activation in regulating SC proliferation and HC regeneration. Simultaneously inhibiting Notch and overexpressing Wnt led to significantly greater SC proliferation and greater numbers of HCs than manipulating either pathway alone. Similar results were observed in the transgenic mice. This study suggests that the combination of Notch inhibition and Wnt activation can significantly promote SC proliferation and increase the number of regenerated HCs in mouse utricle.
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Affiliation(s)
- Jingfang Wu
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China
| | - Wenyan Li
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China
| | - Chen Lin
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China
| | - Yan Chen
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Central laboratory, Affiliated Eye and ENT Hospital of Fudan University, Shanghai, 200031, PR China.,Key Laboratory of Hearing Medicine of National Health and Family Planning Commission, Shanghai, 200031, PR China
| | - Cheng Cheng
- MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, PR China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, PR China
| | - Shan Sun
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Central laboratory, Affiliated Eye and ENT Hospital of Fudan University, Shanghai, 200031, PR China.,Key Laboratory of Hearing Medicine of National Health and Family Planning Commission, Shanghai, 200031, PR China
| | - Mingliang Tang
- MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, PR China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, PR China
| | - Renjie Chai
- MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, PR China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, PR China
| | - Huawei Li
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China.,Key Laboratory of Hearing Medicine of National Health and Family Planning Commission, Shanghai, 200031, PR China
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Abstract
Apoptosis is a primary characteristic in the pathogenesis of liver disease. Hepatic apoptosis is regulated by autophagic activity. However, mechanisms mediating their interaction remain to be determined. Basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy also is an adaptive response under stressful conditions. Autophagy can control cell fate through different cross-talk signals. A complex interplay between hepatic autophagy and apoptosis determines the degree of hepatic apoptosis and the progression of liver disease as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances on roles of autophagy that plays in pathophysiology of liver. The autophagic pathway can be a novel therapeutic target for liver disease.
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Key Words
- ALT, alanine aminotransferase
- AMBRA-1, activating molecule in Beclin-1-regulated autophagy
- APAP, N-acetyl-p-aminophenol
- ATP, adenosine triphosphate
- Atg, autophagy-related gene
- BH3, Bcl-2 homology domain-3
- BNIP, Bcl-2/adenovirus E1B 19 kd-interacting protein
- Barkor, Beclin-1-associated autophagy-related key regulator
- Bcl-2, B-cell lymphoma-2
- Bcl-xL, B-cell lymphoma extra long
- Beclin-1, Bcl-2-interacting protein-1
- CSE, cigarette smoke extract
- DISC, death-inducing signaling complex
- DNA, DNA
- DRAM, damage regulated autophagic modulator
- Drp1, dynamin-related protein 1
- ER stress, endoplasmic reticulum stress
- FADD, Fas-associated protein with death domain
- FFA, free fatty acids
- HBV, hepatitis B virus
- HBx, hepatitis B X protein
- HCC, hepatocellular carcinoma
- HCV, hepatitis C virus
- HSC, hepatic stellate cells
- LAMP-2, lysosome-associated membrane protein 2
- LD, lipid droplets
- MDBs, Mallory-Denk bodies
- MOMP, mitochondrial outer membrane permiabilization
- Microtubule LC3, microtubule light chain 3
- PCD, programmed cell death
- PI3KC3, phosphatidylinositol-3-kinase class-3
- RNA, ribonucleic acid
- ROS, reactive oxygen species
- TNFα, tumor necrosis factor-α
- TUNEL, terminal deoxynucleotidyl transferase dUTP nick-end labeling
- UVRAG, UV-resistance-associated gene
- Vps34, vacuolar protein sorting-34
- apoptosis
- autophagy
- c-FLIP, cellular FLICE-like inhibitor protein
- cross-talk
- liver injury
- mTOR, mammalian target of rapamycin
- mechanism
- siRNA, small interfering RNA
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Affiliation(s)
- Kewei Wang
- a Departments of Surgery; University of Illinois College of Medicine ; Peoria , IL , USA
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Brosel S, Laub C, Averdam A, Bender A, Elstner M. Molecular aging of the mammalian vestibular system. Ageing Res Rev 2016; 26:72-80. [PMID: 26739358 DOI: 10.1016/j.arr.2015.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 12/16/2015] [Accepted: 12/21/2015] [Indexed: 12/18/2022]
Abstract
Dizziness and imbalance frequently affect the elderly and contribute to falls and frailty. In many geriatric patients, clinical testing uncovers a dysfunction of the vestibular system, but no specific etiology can be identified. Neuropathological studies have demonstrated age-related degeneration of peripheral and central vestibular neurons, but the molecular mechanisms are poorly understood. In contrast, recent studies into age-related hearing loss strongly implicate mitochondrial dysfunction, oxidative stress and apoptotic cell death of cochlear hair cells. While some data suggest that analogous biological pathomechanisms may underlie vestibular dysfunction, actual proof is missing. In this review, we summarize the available data on the molecular causes of vestibular dysfunction.
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Affiliation(s)
- Sonja Brosel
- German Center for Vertigo and Balance Disorders, Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany.
| | - Christoph Laub
- Department of Neurology with Friedrich-Baur-Institute, Klinikum Grosshadern, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany
| | - Anne Averdam
- Department of Neurology with Friedrich-Baur-Institute, Klinikum Grosshadern, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany
| | - Andreas Bender
- Department of Neurology, Therapiezentrum Burgau, Kapuzinerstr.34, 89331 Burgau, Germany
| | - Matthias Elstner
- Department of Neurology with Friedrich-Baur-Institute, Klinikum Grosshadern, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany; Department of Neurology and Clinical Neurophysiology, Academic Hospital Munich-Bogenhausen, Technical University of Munich, Englschalkingerstr. 77, 81925 Munich, Germany
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Sox2-CreER mice are useful for fate mapping of mature, but not neonatal, cochlear supporting cells in hair cell regeneration studies. Sci Rep 2015; 5:11621. [PMID: 26108463 PMCID: PMC4479870 DOI: 10.1038/srep11621] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 06/01/2015] [Indexed: 01/06/2023] Open
Abstract
Studies of hair cell regeneration in the postnatal cochlea rely on fate mapping of supporting cells. Here we characterized a Sox2-CreER knock-in mouse line with two independent reporter mouse strains at neonatal and mature ages. Regardless of induction age, reporter expression was robust, with CreER activity being readily detectable in >85% of supporting cells within the organ of Corti. When induced at postnatal day (P) 28, Sox2-CreER activity was exclusive to supporting cells demonstrating its utility for fate mapping studies beyond this age. However, when induced at P1, Sox2-CreER activity was also detected in >50% of cochlear hair cells, suggesting that Sox2-CreER may not be useful to fate map a supporting cell origin of regenerated hair cells if induced at neonatal ages. Given that this model is currently in use by several investigators for fate mapping purposes, and may be adopted by others in the future, our finding that current protocols are effective for restricting CreER activity to supporting cells at mature but not neonatal ages is both significant and timely.
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Cockayne syndrome group B (Csb) and group a (Csa) deficiencies predispose to hearing loss and cochlear hair cell degeneration in mice. J Neurosci 2015; 35:4280-6. [PMID: 25762674 DOI: 10.1523/jneurosci.5063-14.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Sensory hair cells in the cochlea, like most neuronal populations that are postmitotic, terminally differentiated, and non-regenerating, depend on robust mechanisms of self-renewal for lifelong survival. We report that hair cell homeostasis requires a specific sub-branch of the DNA damage nucleotide excision repair pathway, termed transcription-coupled repair (TCR). Cockayne syndrome (CS), caused by defects in TCR, is a rare DNA repair disorder with a broad clinical spectrum that includes sensorineural hearing loss. We tested hearing and analyzed the cellular integrity of the organ of Corti in two mouse models of this disease with mutations in the Csb gene (CSB(m/m) mice) and Csa gene (Csa(-/-) mice), respectively. Csb(m/m) and Csa(-/-) mice manifested progressive hearing loss, as measured by an increase in auditory brainstem response thresholds. In contrast to wild-type mice, mutant mice showed reduced or absent otoacoustic emissions, suggesting cochlear outer hair cell impairment. Hearing loss in Csb(m/m) and Csa(-/-) mice correlated with progressive hair cell loss in the base of the organ of Corti, starting between 6 and 13 weeks of age, which increased by 16 weeks of age in a basal-to-apical gradient, with outer hair cells more severely affected than inner hair cells. Our data indicate that the hearing loss observed in CS patients is reproduced in mouse models of this disease. We hypothesize that accumulating DNA damage, secondary to the loss of TCR, contributes to susceptibility to hearing loss.
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