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1.
Aquat Toxicol ; 215: 105273, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31445453

RESUMO

The potential toxicity of nanoparticles (NPs) to the early stages of fish is still unclear. In this study, we investigated the toxic effects of silver (AgNPs) and copper nanoparticles (CuNPs) on lateral-line hair cells of zebrafish embryos. Zebrafish embryos were incubated in different concentrations of AgNPs and CuNPs at 0˜96 h post-fertilization (hpf). Both AgNPs and CuNPs were found to cause toxic effects in zebrafish embryos in a dose-dependent manner. Values of the 96-h 50% lethal concentration (LC50) of AgNPs and CuNPs were 6.1 ppm (56.5 µM) and 2.61 ppm (41.1 µM), respectively. The number of FM1-43-labeled hair cells and the microstructure of hair bundles were significantly impaired by AgNPs [≥1 ppm (9.3 µM)] and CuNPs [≥0.01 ppm (0.16 µM)]. Ca2+ influxes at hair bundles of hair cells were measured with a scanning ion-selective microelectrode technique to evaluate the function of hair cells. AgNPs [≥0.1 ppm (0.9 µM)] and CuNPs [≥0.01 ppm (0.16 µM)] were both found to significantly reduce Ca2+ influxes. Similar toxic effects were also found in hatched embryos subjected to 4 h of exposure (96˜100 hpf) to AgNPs and CuNPs. This study revealed that lateral-line hair cells of zebrafish are susceptible to AgNPs and CuNPs, and these contaminants in aquatic environments could pose a threat to fish survival.


Assuntos
Cobre/toxicidade , Embrião não Mamífero/citologia , Células Ciliadas Auditivas/citologia , Sistema da Linha Lateral/embriologia , Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Peixe-Zebra/embriologia , Animais , Embrião não Mamífero/anatomia & histologia , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/ultraestrutura , Exposição Ambiental , Células Ciliadas Auditivas/ultraestrutura , Dose Letal Mediana , Nanopartículas Metálicas/ultraestrutura , Análise de Sobrevida , Poluentes Químicos da Água/toxicidade
2.
Nat Commun ; 10(1): 1117, 2019 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-30850599

RESUMO

Sensory hair cells, the mechanoreceptors of the auditory and vestibular systems, harbor two specialized elaborations of the apical surface, the hair bundle and the cuticular plate. In contrast to the extensively studied mechanosensory hair bundle, the cuticular plate is not as well understood. It is believed to provide a rigid foundation for stereocilia motion, but specifics about its function, especially the significance of its integrity for long-term maintenance of hair cell mechanotransduction, are not known. We discovered that a hair cell protein called LIM only protein 7 (LMO7) is specifically localized in the cuticular plate and the cell junction. Lmo7 KO mice suffer multiple cuticular plate deficiencies, including reduced filamentous actin density and abnormal stereociliar rootlets. In addition to the cuticular plate defects, older Lmo7 KO mice develop abnormalities in inner hair cell stereocilia. Together, these defects affect cochlear tuning and sensitivity and give rise to late-onset progressive hearing loss.


Assuntos
Células Ciliadas Auditivas/fisiologia , Audição/fisiologia , Proteínas com Domínio LIM/deficiência , Fatores de Transcrição/deficiência , Actinas/metabolismo , Animais , Cóclea/fisiologia , Modelos Animais de Doenças , Células Ciliadas Auditivas/ultraestrutura , Células Ciliadas Auditivas Internas/fisiologia , Células Ciliadas Auditivas Internas/ultraestrutura , Audição/genética , Perda Auditiva/etiologia , Perda Auditiva/genética , Perda Auditiva/fisiopatologia , Proteínas com Domínio LIM/genética , Proteínas com Domínio LIM/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Knockout , Microscopia Eletrônica de Varredura , Estereocílios/genética , Estereocílios/fisiologia , Estereocílios/ultraestrutura , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia
3.
Int J Neurosci ; 129(6): 580-587, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30475092

RESUMO

AIMS: Hearing loss is the most common form of sensory impairment in humans. Short impulses of a high intensity noise can trigger sudden hearing loss, which is generally irreversible and associated with structural tissue damage of the cochlea and auditory nerve. It is well established that myelination is essential for the rapid propagation of action potentials along axons, and that Schwann cells are responsible for myelin sheath production in the peripheral nervous system. In the cochlea, spiral ganglion neuron axons are myelinated by Schwann cells. This myelin contributes to axonal protection and allows for efficient action potential transmission along the auditory nerve. For this reason, here we studie the morphological changes on cochlear hair cells and myelin sheaths of the auditory nerve, directly linked to hearing impairment induced by acoustic trauma. MATERIAL AND METHODS: To study the auditory functions, auditory brainstem responses and distortion products were measured at baseline, 2 days, and 21 days after trauma in rats. Then, scanning and transmission electron microscopy techniques were performed to analyze cochleae and the auditory nerve at 21 days after trauma. RESULTS: We observed that acoustic trauma induced cochlear outer hair cell loss and fusion of inner hair cell stereocilia. We also observed an axonal loss and myelin sheath disorganization of the auditory nerve. CONCLUSIONS: These data confirm that a strong acoustic trauma induced histological changes in the cochlea and auditory nerve, leading to permanent hearing loss.


Assuntos
Nervo Coclear/patologia , Células Ciliadas Auditivas/patologia , Perda Auditiva Provocada por Ruído/patologia , Bainha de Mielina/patologia , Animais , Nervo Coclear/ultraestrutura , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Células Ciliadas Auditivas/ultraestrutura , Perda Auditiva Provocada por Ruído/fisiopatologia , Masculino , Bainha de Mielina/ultraestrutura , Degeneração Neural/patologia , Ratos
4.
Cell Rep ; 25(5): 1268-1280.e4, 2018 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30380417

RESUMO

Mutations in human GRXCR2, which encodes a protein of undetermined function, cause hearing loss by unknown mechanisms. We found that mouse GRXCR2 localizes to the base of the stereocilia, which are actin-based mechanosensing organelles in cochlear hair cells that convert sound-induced vibrations into electrical signals. The stereocilia base also contains taperin, another protein of unknown function required for human hearing. We show that taperin and GRXCR2 form a complex and that taperin is diffused throughout the stereocilia length in Grxcr2-deficient hair cells. Stereocilia lacking GRXCR2 are longer than normal and disorganized due to the mislocalization of taperin, which could modulate the actin cytoskeleton in stereocilia. Remarkably, reducing taperin expression levels could rescue the morphological defects of stereocilia and restore the hearing of Grxcr2-deficient mice. Thus, our findings suggest that GRXCR2 is critical for the morphogenesis of stereocilia and auditory perception by restricting taperin to the stereocilia base.


Assuntos
Glutarredoxinas/metabolismo , Audição , Proteínas/metabolismo , Estereocílios/metabolismo , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/ultraestrutura , Animais , Células COS , Surdez/metabolismo , Surdez/patologia , Surdez/fisiopatologia , Potenciais Evocados Auditivos do Tronco Encefálico , Glutarredoxinas/deficiência , Células HEK293 , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/ultraestrutura , Humanos , Camundongos Endogâmicos C57BL , Ligação Proteica , Estereocílios/ultraestrutura
5.
Sci Rep ; 8(1): 12125, 2018 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-30108230

RESUMO

Mouse Tmc1 and Tmc2 are required for sensory transduction in cochlear and vestibular hair cells. Homozygous Tmc1∆/∆ mice are deaf, Tmc2∆/∆ mice have normal hearing, and double homozygous Tmc1∆/∆; Tmc2∆/∆ mice have deafness and profound vestibular dysfunction. These phenotypes are consistent with their different spatiotemporal expression patterns. Tmc1 expression is persistent in cochlear and vestibular hair cells, whereas Tmc2 expression is transient in cochlear hair cells but persistent in vestibular hair cells. On the basis of these findings, we hypothesized that persistent Tmc2 expression in mature cochlear hair cells could restore auditory function in Tmc1∆/∆ mice. To express Tmc2 in mature cochlear hair cells, we generated a transgenic mouse line, Tg[PTmc1::Tmc2], in which Tmc2 cDNA is expressed under the control of the Tmc1 promoter. The Tg[PTmc1::Tmc2] transgene slightly but significantly restored hearing in young Tmc1∆/∆ mice, though hearing thresholds were elevated with age. The elevation of hearing thresholds was associated with deterioration of sensory transduction in inner hair cells and loss of outer hair cell function. Although sensory transduction was retained in outer hair cells, their stereocilia eventually degenerated. These results indicate distinct roles and requirements for Tmc1 and Tmc2 in mature cochlear hair cells.


Assuntos
Células Ciliadas Auditivas/patologia , Perda Auditiva Neurossensorial/patologia , Proteínas de Membrana/metabolismo , Estereocílios/patologia , Animais , Modelos Animais de Doenças , Células Ciliadas Auditivas/citologia , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/ultraestrutura , Células Ciliadas Vestibulares/metabolismo , Perda Auditiva Neurossensorial/diagnóstico , Perda Auditiva Neurossensorial/genética , Testes Auditivos , Homozigoto , Humanos , Mecanotransdução Celular , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Microscopia Eletrônica de Varredura , Mutação , Técnicas de Patch-Clamp , Regiões Promotoras Genéticas/genética , Estereocílios/ultraestrutura
6.
Cell Rep ; 23(10): 2901-2914.e13, 2018 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-29874578

RESUMO

Protruding from the apical surface of inner ear sensory cells, hair bundles carry out mechanotransduction. Bundle growth involves sequential and overlapping cellular processes, which are concealed within gene expression profiles of individual cells. To dissect such processes, we developed CellTrails, a tool for uncovering, analyzing, and visualizing single-cell gene-expression dynamics. Utilizing quantitative gene-expression data for key bundle proteins from single cells of the developing chick utricle, we reconstructed de novo a bifurcating trajectory that spanned from progenitor cells to mature striolar and extrastriolar hair cells. Extraction and alignment of developmental trails and association of pseudotime with bundle length measurements linked expression dynamics of individual genes with bundle growth stages. Differential trail analysis revealed high-resolution dynamics of transcripts that control striolar and extrastriolar bundle development, including those that encode proteins that regulate [Ca2+]i or mediate crosslinking and lengthening of actin filaments.


Assuntos
Células Ciliadas Auditivas/citologia , Morfogênese/genética , Software , Transcrição Genética , Animais , Animais Recém-Nascidos , Cálcio/metabolismo , Diferenciação Celular , Galinhas , Regulação da Expressão Gênica no Desenvolvimento , Células Ciliadas Auditivas/ultraestrutura , Camundongos , Sáculo e Utrículo/citologia , Fatores de Tempo
7.
Elife ; 72018 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-29893686

RESUMO

The lateral-line neuromast of the zebrafish displays a restricted, consistent pattern of innervation that facilitates the comparison of microcircuits across individuals, developmental stages, and genotypes. We used serial blockface scanning electron microscopy to determine from multiple specimens the neuromast connectome, a comprehensive set of connections between hair cells and afferent and efferent nerve fibers. This analysis delineated a complex but consistent wiring pattern with three striking characteristics: each nerve terminal is highly specific in receiving innervation from hair cells of a single directional sensitivity; the innervation is redundant; and the terminals manifest a hierarchy of dominance. Mutation of the canonical planar-cell-polarity gene vangl2, which decouples the asymmetric phenotypes of sibling hair-cell pairs, results in randomly positioned, randomly oriented sibling cells that nonetheless retain specific wiring. Because larvae that overexpress Notch exhibit uniformly oriented, uniformly innervating hair-cell siblings, wiring specificity is mediated by the Notch signaling pathway.


Assuntos
Vias Aferentes/fisiologia , Vias Eferentes/fisiologia , Células Ciliadas Auditivas/fisiologia , Sistema da Linha Lateral/fisiologia , Vias Neurais/fisiologia , Peixe-Zebra/fisiologia , Vias Aferentes/citologia , Animais , Axônios/fisiologia , Axônios/ultraestrutura , Polaridade Celular , Vias Eferentes/citologia , Embrião não Mamífero , Gânglios/citologia , Gânglios/fisiologia , Expressão Gênica , Células Ciliadas Auditivas/ultraestrutura , Larva/anatomia & histologia , Larva/fisiologia , Sistema da Linha Lateral/citologia , Sistema da Linha Lateral/inervação , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutação , Fibras Nervosas/fisiologia , Fibras Nervosas/ultraestrutura , Vias Neurais/ultraestrutura , Imagem Óptica , Receptores Notch/genética , Receptores Notch/metabolismo , Transdução de Sinais , Peixe-Zebra/anatomia & histologia , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
8.
Neural Plast ; 2018: 5616930, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29849558

RESUMO

The auditory function develops and matures after birth in many mammalian species. After hearing onset, environmental sounds exert profound and long-term effects on auditory functions. However, the effects of the acoustic environment on the functional development of the peripheral auditory system, especially the cochlear sensory hair cells, are still unclear. In the present study, we exposed mouse pups to frequency-enriched acoustic environments in postnatal days 0-14. The results indicated that the acoustic environment significantly decreased the threshold of the auditory brainstem response in a frequency-specific manner. Compared with controls, no difference was found in the number and alignment of inner and outer hair cells or in the length of hair bundles after acoustic overstimulation. The expression and function of prestin, the motor protein of outer hair cells (OHCs), were specifically increased in OHCs activated by acoustic stimulation at postnatal days 7-11. We analyzed the postnatal maturation of ribbon synapses in the hair cell areas. After acoustic stimulation, the number of ribbon synapses was closer to the mature stage than to the controls. Taken together, these data indicate that early acoustic exposure could promote the functional maturation of cochlear hair cells and the development of hearing.


Assuntos
Cóclea/crescimento & desenvolvimento , Meio Ambiente , Células Ciliadas Auditivas/fisiologia , Audição , Som , Estimulação Acústica , Animais , Limiar Auditivo , Potenciais Evocados Auditivos do Tronco Encefálico , Feminino , Células Ciliadas Auditivas/ultraestrutura , Masculino , Camundongos Endogâmicos C57BL , Proteínas Motores Moleculares/metabolismo , Sinapses/fisiologia
9.
Ann Anat ; 218: 183-189, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29719206

RESUMO

The neuromast is the morphological unit of the lateral line of fishes and is composed of a cluster of central sensory cells (hair cells) surrounded by support and mantle cells. Heavy metals exposure leads to disruption of hair cells within the neuromast. It is well known that the zebrafish has the ability to regenerate the hair cells after damage caused by toxicants. The process of regeneration depends on proliferation, differentiation and cellular migration of sensory and non-sensory progenitor cells. Therefore, our study was made in order to identify which cellular types are involved in the complex process of regeneration during heavy metals exposure. For this purpose, adult zebrafish were exposed to various heavy metals (Arsenic, cadmium and zinc) for 72h. After acute (24h) exposure, immunohistochemical localization of S100 (a specific marker for hair cells) in the neuromasts highlighted the hair cells loss. The immunoreaction for Sox2 (a specific marker for stem cells), at the same time, was observed in the support and mantle cells, after exposure to arsenic and cadmium, while only in the support cells after exposure to zinc. After chronic (72h) exposure the hair cells were regenerated, showing an immunoreaction for S100 protein. At the same exposure time to the three metals, a Sox2 immunoreaction was expressed in support and mantle cells. Our results showed for the first time the regenerative capacity of hair cells, not only after, but also during exposure to heavy metals, demonstrated by the presence of different stem cells that can diversify in hair cells.


Assuntos
Células Ciliadas Auditivas/fisiologia , Células Ciliadas Auditivas/ultraestrutura , Sistema da Linha Lateral/anatomia & histologia , Sistema da Linha Lateral/efeitos dos fármacos , Metais Pesados/toxicidade , Animais , Arsênico/toxicidade , Cádmio/toxicidade , Imuno-Histoquímica , Sistema da Linha Lateral/citologia , Mecanorreceptores , Regeneração , Fatores de Transcrição SOX , Peixe-Zebra , Proteínas de Peixe-Zebra , Zinco/toxicidade
10.
Toxicol Lett ; 294: 20-26, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29751043

RESUMO

Gentamycin is one of the most clinically used aminoglycoside antibiotics which induce intrinsic apoptosis of hair cells. Tauroursodeoxycholic acid (TUDCA) is known as safe cell-protective agent in disorders associated with apoptosis. We aimed to investigate the protective effects of TUDCA against gentamicin-induced ototoxicity. House Ear Institute-Organ of Corti 1(HEI-OC1) cells and explanted cochlear tissue were treated with gentamicin and TUDCA, followed by serial analyses including cell viability assay, hair cell staining, qPCR, ELISA and western blotting to determine the cell damage by the parameters relevant to cell apoptosis and endoplasmic reticulum stress. TUDCA significantly attenuated gentamicin-induced cell damage in cultured HEI-OC1 cells and explanted cochlear hair cells. TUDCA alleviated gentamicin-induced cell apoptosis, supported by the decreased Bax/Bcl2 ratio compared with that of gentamicin treated alone. TUDCA decreased gentamicin-induced nitric oxide production and protein nitration in both models. In addition, TUDCA suppressed gentamicin-induced endoplasmic reticulum stress as reflected by inversing the expression levels of Binding immunoglobulin protein (Bip), CCAAT/-enhancer-binding protein homologous protein (CHOP) and Caspase 3. TUDCA attenuated gentamicin-induced hair cell death by inhibiting protein nitration activation and ER stress, providing new insights into the new potential therapies for sensorineural deafness.


Assuntos
Antibacterianos/química , Apoptose/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Gentamicinas/antagonistas & inibidores , Células Ciliadas Auditivas/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Ácido Tauroquenodesoxicólico/farmacologia , Animais , Antibacterianos/efeitos adversos , Biomarcadores/metabolismo , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cóclea/efeitos dos fármacos , Cóclea/metabolismo , Cóclea/patologia , Cóclea/ultraestrutura , Regulação da Expressão Gênica/efeitos dos fármacos , Gentamicinas/efeitos adversos , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/patologia , Células Ciliadas Auditivas/ultraestrutura , Perda Auditiva Neurossensorial/induzido quimicamente , Perda Auditiva Neurossensorial/etiologia , Perda Auditiva Neurossensorial/metabolismo , Perda Auditiva Neurossensorial/patologia , Perda Auditiva Neurossensorial/prevenção & controle , Humanos , Camundongos Endogâmicos BALB C , Microscopia Eletrônica de Varredura , Óxido Nítrico Sintase Tipo II/antagonistas & inibidores , Óxido Nítrico Sintase Tipo II/química , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Inibidores da Síntese de Proteínas/efeitos adversos , Inibidores da Síntese de Proteínas/química , Técnicas de Cultura de Tecidos , Tirosina/análogos & derivados , Tirosina/metabolismo
11.
Front Immunol ; 9: 223, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29487598

RESUMO

The human inner ear, which is segregated by a blood/labyrinth barrier, contains resident macrophages [CD163, ionized calcium-binding adaptor molecule 1 (IBA1)-, and CD68-positive cells] within the connective tissue, neurons, and supporting cells. In the lateral wall of the cochlea, these cells frequently lie close to blood vessels as perivascular macrophages. Macrophages are also shown to be recruited from blood-borne monocytes to damaged and dying hair cells induced by noise, ototoxic drugs, aging, and diphtheria toxin-induced hair cell degeneration. Precise monitoring may be crucial to avoid self-targeting. Macrophage biology has recently shown that populations of resident tissue macrophages may be fundamentally different from circulating macrophages. We removed uniquely preserved human cochleae during surgery for treating petroclival meningioma compressing the brain stem, after ethical consent. Molecular and cellular characterization using immunofluorescence with antibodies against IBA1, TUJ1, CX3CL1, and type IV collagen, and super-resolution structured illumination microscopy (SR-SIM) were made together with transmission electron microscopy. The super-resolution microscopy disclosed remarkable phenotypic variants of IBA1 cells closely associated with the spiral ganglion cells. Monitoring cells adhered to neurons with "synapse-like" specializations and protrusions. Active macrophages migrated occasionally nearby damaged hair cells. Results suggest that the human auditory nerve is under the surveillance and possible neurotrophic stimulation of a well-developed resident macrophage system. It may be alleviated by the non-myelinated nerve soma partly explaining why, in contrary to most mammals, the human's auditory nerve is conserved following deafferentiation. It makes cochlear implantation possible, for the advantage of the profoundly deaf. The IBA1 cells may serve additional purposes such as immune modulation, waste disposal, and nerve regeneration. Their role in future stem cell-based therapy needs further exploration.


Assuntos
Cóclea/imunologia , Proteínas de Ligação a DNA/imunologia , Macrófagos/imunologia , Gânglio Espiral da Cóclea/imunologia , Idoso , Proteínas de Ligação ao Cálcio , Movimento Celular/imunologia , Cóclea/citologia , Cóclea/transplante , Cóclea/ultraestrutura , Implante Coclear , Proteínas de Ligação a DNA/metabolismo , Surdez/cirurgia , Feminino , Células Ciliadas Auditivas/imunologia , Células Ciliadas Auditivas/ultraestrutura , Humanos , Imuno-Histoquímica/métodos , Macrófagos/metabolismo , Masculino , Proteínas dos Microfilamentos , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Gânglio Espiral da Cóclea/citologia , Gânglio Espiral da Cóclea/ultraestrutura
12.
Hear Res ; 363: 98-108, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29551307

RESUMO

SOAE from the last major lizard family not yet systematically investigated, the teiids, were collected from the genera Callopistes, Tupinambis and Cnemidophorus. Although their papillae show characteristics of the family Teiidae, the papillae differ both in their size and in the arrangement of uni- and bi-directional hair-cell areas. Among these three genera, Callopistes showed few (2 or 3) SOAE peaks, whereas the other two genera showed more (up to 6 per ear). In the absence of knowledge of the tonotopic maps, however, it was not possible to clearly relate the spectral patterns to the differences in papillar anatomy, suggesting that the determinants of these patterns may be more subtle than anticipated.


Assuntos
Cóclea/fisiologia , Lagartos/fisiologia , Emissões Otoacústicas Espontâneas , Estimulação Acústica , Animais , Temperatura Corporal , Cóclea/ultraestrutura , Feminino , Células Ciliadas Auditivas/fisiologia , Células Ciliadas Auditivas/ultraestrutura , Lagartos/classificação , Masculino , Especificidade da Espécie
13.
Int J Toxicol ; 37(3): 195-206, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29575954

RESUMO

The function and structure of the auditory information processing system establishes a unique sensory environment for the "perfect storm." The battle between life and death pits the cascade of an apoptotic storm, programmed cell death cascades, against simple cell death (necrosis) pathways. Live or die, the free radical biology of oxygen and hydroxylation, and the destruction of transition metal migration through the mechanical gate sensory processes of the hair cell lead to direct access to the cytoplasm, cytoplasmic reticulum, and mitochondria of the inner workings of the hair cells. These lead to subsequent interactions with nuclear DNA resulting in permanent hearing loss. The yin and yang of pharmaceutical product development is to document what kills, why it kills, and how do we mitigate it. This review highlights the processes of cell death within the cochlea.


Assuntos
Células Ciliadas Auditivas/fisiologia , Animais , Apoptose/fisiologia , Morte Celular/fisiologia , Cóclea/efeitos dos fármacos , Cóclea/fisiologia , Cóclea/ultraestrutura , Células Ciliadas Auditivas/efeitos dos fármacos , Células Ciliadas Auditivas/ultraestrutura , Humanos
14.
Sci Rep ; 8(1): 4393, 2018 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-29535354

RESUMO

Fluorescent polydopamine nanoparticles (FPNPs) are prepared via the ethylenediamine (EDA)-induced degradation of as-prepared non-fluorescent polydopamine (PDA) and used for targeted bioimaging. The reductive treatment of PDA in the presence of EDA yields fluorescent precipitates, inspiring us to seek various biological approaches to preparing FPNPs with excellent optical and biocompatible properties. Moreover, we firstly found that FPNPs selectively label neuromast hair cells in the lateral line of zebrafish, their applications as a reliable fluorescent indicator to investigate the neuromast hair cells, to in turn determine the viability of hair cells, was demonstrated. FPNPs also provided a minimal toxicity enable to assay the number of functional hair cells per neuromast in live animals as development proceeds. Upon combined incubation with TO-PRO-3, a well-established hair cell marker, all hair cells that were rapidly labeled with FPNPs were observed to be also completely labeled with the TO-PRO-3, labeling hair cells in neuromasts positioned in the supraorbital, otic and occipital lateral line as well as in posterior lateral line of living zebrafish larvae. Their potential efficacy for biological applications was demonstrated by their excellent optical and biocompatible properties, offering new opportunities in cancer research, real-time monitoring of stem cell transplantation and other cell-based therapies.


Assuntos
Corantes Fluorescentes , Células Ciliadas Auditivas/metabolismo , Indóis , Imagem Molecular , Nanopartículas , Polímeros , Animais , Biomarcadores , Corantes Fluorescentes/química , Células Ciliadas Auditivas/ultraestrutura , Células HeLa , Humanos , Indóis/química , Nanopartículas/química , Polímeros/química , Análise Espectral , Peixe-Zebra
15.
Toxicol Appl Pharmacol ; 343: 16-28, 2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29454061

RESUMO

To date, the mechanism (s) underlying the cisplatin-elicited ototoxicity has not been elucidated fully. Nucleotide-binding domain and leucine-rich-repeat-containing family member ×1 (NLRX1), a cytoplasmic pattern recognition receptor, is tightly related to mitochondrial function, reactive oxygen species (ROS) production, and autophagy. In this work, autophagy alteration, NLRX1 expression, ROS generation and cell injury were investigated correspondingly by immunofluorescence staining, western-blot, TEM, flow cytometry and MTT in HEI-OC1 cells of both NLRX1 overexpression and silencing in response to cisplatin stimulus. We found that NLRX1 expression was increased concurrent with the increase of autophagy activation in HEI-OC1 cells under the cisplatin insult. NLRX1 overexpression led to the amount of accumulation of autophagsomes in HEI-OC1 cells in normal condition and a higher activation of autophagy concurrent with cell injury in HEI-OC1 cells treated with cisplatin, whereas, NLRX1 silencing decreased the activation level of autophagy concurrent with increased cell viability in HEI-OC1 cells treated with cisplatin. Mechanistic studies showed that NLRX1 potentiated mitochondrial-derived ROS generation in response to cisplatin exposure. Inhibition of ROS generation significantly prevented autophagy activation and apoptosis both in HEI-OC1cells and cochlear explants treated with cisplatin. The findings from this work reveal that NLRX1 sensitizes auditory cells in vitro to cisplatin-induced ototoxity via autophagic cell death pathway, providing another strategy against cisplatin-induced ototoxity.


Assuntos
Antineoplásicos/toxicidade , Autofagia/fisiologia , Cisplatino/toxicidade , Células Ciliadas Auditivas/metabolismo , Proteínas Mitocondriais/metabolismo , Animais , Autofagia/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Relação Dose-Resposta a Droga , Células Ciliadas Auditivas/efeitos dos fármacos , Células Ciliadas Auditivas/ultraestrutura , Camundongos , Camundongos Endogâmicos C57BL , Órgão Espiral/efeitos dos fármacos , Órgão Espiral/metabolismo , Órgão Espiral/ultraestrutura , Espécies Reativas de Oxigênio/metabolismo
16.
Mol Neurobiol ; 55(8): 6518-6532, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29327200

RESUMO

The exocyst, an octameric protein complex consisting of Exoc1 through Exoc8, was first determined to regulate exocytosis by targeting vesicles to the plasma membrane in yeast to mice. In addition to this fundamental role, the exocyst complex has been implicated in other cellular processes. In this study, we investigated the role of the exocyst in cochlear development and hearing by targeting EXOC5, a central exocyst component. Deleting Exoc5 in the otic epithelium with widely used Cre lines resulted in early lethality. Thus, we generated two different inner ear-specific Exoc5 knockout models by crossing Gfi1Cre mice with Exoc5f/f mice for hair cell-specific deletion (Gfi1Cre/+;Exoc5f/f) and by in utero delivery of rAAV-iCre into the otocyst of embryonic day 12.5 for deletion throughout the otic epithelium (rAAV2/1-iCre;Exoc5f/f). Gfi1Cre/+;Exoc5f/f mice showed relatively normal hair cell morphology until postnatal day 20, after which hair cells underwent apoptosis accompanied by disorganization of stereociliary bundles, resulting in progressive hearing loss. rAAV2/1-iCre;Exoc5f/f mice exhibited abnormal neurite morphology, followed by apoptotic degeneration of spiral ganglion neurons (SGNs) and hair cells, which led to profound and early-onset hearing loss. These results demonstrate that Exoc5 is essential for the normal development and survival of cochlear hair cells and SGNs, as well as the functional maintenance of hearing.


Assuntos
Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/patologia , Audição , Neurônios/patologia , Gânglio Espiral da Cóclea/patologia , Proteínas de Transporte Vesicular/metabolismo , Animais , Apoptose , Sobrevivência Celular , Proteínas de Ligação a DNA/metabolismo , Dependovirus/metabolismo , Epitélio/patologia , Células Ciliadas Auditivas/ultraestrutura , Perda Auditiva/metabolismo , Perda Auditiva/patologia , Integrases/metabolismo , Camundongos Endogâmicos C57BL , Degeneração Neural/patologia , Neuritos/metabolismo , Neurônios/metabolismo , Órgão Espiral/metabolismo , Órgão Espiral/ultraestrutura , Estereocílios/metabolismo , Estereocílios/ultraestrutura , Fatores de Transcrição/metabolismo , Proteínas de Transporte Vesicular/deficiência
17.
J Comp Neurol ; 526(6): 957-971, 2018 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-29277977

RESUMO

In tunicates, the coronal organ represents a sentinel checking particle entrance into the pharynx. The organ differentiates from an anterior embryonic area considered a proto-placode. For their embryonic origin, morphological features and function, coronal sensory cells have been hypothesized to be homologues to vertebrate hair cells. However, vertebrate hair cells derive from a posterior placode. This contradicts one of the principle historical criteria for homology, similarity of position, which could be taken as evidence against coronal cells/hair cells homology. In the tunicates Ciona intestinalis and C. robusta, we found that the coronal organ expresses genes (Atoh, Notch, Delta-like, Hairy-b, and Musashi) characterizing vertebrate neural and hair cell development. Moreover, coronal cells exhibit a complex synaptic connectivity pattern, and express neurotransmitters (Glu, ACh, GABA, 5-HT, and catecholamines), or enzymes for their synthetic machinery, involved in hair cell activity. Lastly, coronal cells express the Trpa gene, which encodes an ion channel expressed in hair cells. These data lead us to hypothesize a model in which competence to make secondary mechanoreceptors was initially broadly distributed through placode territories, but has become confined to different placodes during the evolution of the vertebrate and tunicate lineages.


Assuntos
Evolução Biológica , Células Ciliadas Auditivas/citologia , Sinapses/fisiologia , Transmissão Sináptica/fisiologia , Urocordados/citologia , Acetilcolinesterase/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Embrião não Mamífero , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Células Ciliadas Auditivas/ultraestrutura , Mecanorreceptores , Microscopia Eletrônica de Transmissão , RNA Mensageiro/metabolismo , Receptores Notch/genética , Receptores Notch/metabolismo , Transdução de Sinais/fisiologia , Sinapses/ultraestrutura , Transmissão Sináptica/genética , Vertebrados , Proteínas Vesiculares de Transporte de Glutamato/metabolismo , Proteínas Vesiculares de Transporte de Glutamato/ultraestrutura , Ácido gama-Aminobutírico/metabolismo
18.
Elife ; 62017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-29140244

RESUMO

Hair cells are specialized sensors located in the inner ear that enable the transduction of sound, motion, and gravity into neuronal impulses. In birds some hair cells contain an iron-rich organelle, the cuticulosome, that has been implicated in the magnetic sense. Here, we exploit histological, transcriptomic, and tomographic methods to investigate the development of cuticulosomes, as well as the molecular and subcellular architecture of cuticulosome positive hair cells. We show that this organelle forms rapidly after hatching in a process that involves vesicle fusion and nucleation of ferritin nanoparticles. We further report that transcripts involved in endocytosis, extracellular exosomes, and metal ion binding are differentially expressed in cuticulosome positive hair cells. These data suggest that the cuticulosome and the associated molecular machinery regulate the concentration of iron within the labyrinth of the inner ear, which might indirectly tune a magnetic sensor that relies on electromagnetic induction.


Assuntos
Columbidae , Vesículas Citoplasmáticas/metabolismo , Vesículas Citoplasmáticas/ultraestrutura , Células Ciliadas da Ampola/ultraestrutura , Células Ciliadas Auditivas/ultraestrutura , Organelas/metabolismo , Organelas/ultraestrutura , Animais , Transporte Biológico , Perfilação da Expressão Gênica , Células Ciliadas da Ampola/fisiologia , Células Ciliadas Auditivas/fisiologia , Histocitoquímica , Tomografia
19.
Sci Rep ; 7(1): 13480, 2017 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-29044151

RESUMO

Usher syndrome type III (USH3) characterized by progressive loss of vision and hearing is caused by mutations in the clarin-1 gene (CLRN1). Clrn1 knockout (KO) mice develop hair cell defects by postnatal day 2 (P2) and are deaf by P21-P25. Early onset profound hearing loss in KO mice and lack of information about the cochlear cell type that requires Clrn1 expression pose challenges to therapeutic investigation. We generated KO mice harboring a transgene, TgAC1, consisting of Clrn1-UTR (Clrn1 cDNA including its 5' and 3' UTR) under the control of regulatory elements (Atoh1 3' enhancer/ß-globin basal promoter) to direct expression of Clrn1 in hair cells during development and down regulate it postnatally. The KO-TgAC1 mice displayed delayed onset progressive hearing loss associated with deterioration of the hair bundle structure, leading to the hypothesis that hair cell expression of Clrn1 is essential for postnatal preservation of hair cell structure and hearing. Consistent with that hypothesis, perinatal transfection of hair cells in KO-TgAC1 mice with a single injection of AAV-Clrn1-UTR vector showed correlative preservation of the hair bundle structure and hearing through adult life. Further, the efficacy of AAV-Clrn1 vector was significantly attenuated, revealing the potential importance of UTR in gene therapy.


Assuntos
Perda Auditiva/diagnóstico , Perda Auditiva/etiologia , Síndromes de Usher/complicações , Animais , Sequência de Bases , Dependovirus/genética , Modelos Animais de Doenças , Expressão Gênica , Ordem dos Genes , Vetores Genéticos/genética , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/ultraestrutura , Perda Auditiva/prevenção & controle , Humanos , Imuno-Histoquímica , Proteínas de Membrana/química , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Especificidade de Órgãos , Fenótipo , Transporte Proteico , Transdução Genética , Síndromes de Usher/diagnóstico , Síndromes de Usher/etiologia
20.
Adv Clin Exp Med ; 26(6): 893-897, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29068588

RESUMO

BACKGROUND: Oxidative stress has been associated with pathological processes involved in acoustic trauma. OBJECTIVES: In this prospective experimental study, we investigated the potential preventive effect of N-acetyl cysteine (NAC) in rats exposed to acoustic trauma (AT). Light microscopic and scanning electron microscopic (SEM) evaluations were performed. MATERIAL AND METHODS: Healthy Wistar albino rats (n = 18) were divided into 3 groups: group 1 (control group, n = 6), group 2 (acoustic trauma group, n = 6), and group 3 (AT+NAC group, n = 6). The rats in group 2 were exposed to AT. The rats in group 3 received NAC at a dose of 100 mg/kg/day by gavage for 7 days, and then 10 min after the 7th-day dose, they were exposed to AT. RESULTS: From light and scanning electron microscopy evaluations in the control group, the cochlear structure and epithelium were normal. In group 2 (AT group), extensive hair cell loss was observed in the cochlea by light microscopy evaluation. In the SEM evaluation, various epithelial damage and loss of stereocilia were also observed. In group 3 (AT+NAC group), decreased damage with preserved cochlear structures was seen by light microscopy. In the SEM evaluation, although stereocilia loss was also seen, nearly normal cell structures and vertical and symmetrical alignment of stereocilia structures were observed compared to the AT group. CONCLUSIONS: NAC reduced cochlear damage due to acoustic trauma. Because NAC has antioxidant capacity, AT mat have caused an increase in free radicals and death of outer hair cells. NAC is an antioxidant agent and it prevented cochlear damage due to AT in rats.


Assuntos
Acetilcisteína/farmacologia , Antioxidantes/farmacologia , Cóclea/efeitos dos fármacos , Perda Auditiva Provocada por Ruído/prevenção & controle , Microscopia Eletroquímica de Varredura , Ruído/efeitos adversos , Estresse Oxidativo/efeitos dos fármacos , Animais , Cóclea/metabolismo , Cóclea/ultraestrutura , Modelos Animais de Doenças , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/ultraestrutura , Células Ciliadas Auditivas/efeitos dos fármacos , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/ultraestrutura , Perda Auditiva Provocada por Ruído/etiologia , Perda Auditiva Provocada por Ruído/metabolismo , Perda Auditiva Provocada por Ruído/patologia , Ratos Wistar , Estereocílios/efeitos dos fármacos , Estereocílios/ultraestrutura
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