In situ regeneration of inner hair cells in the damaged cochlea by temporally regulated coexpression of Atoh1 and Tbx2
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE188259 | GEO | 2023/11/05
REPOSITORIES: GEO
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Project description:Atoh1 is essential for the development of both outer hair cells (OHCs) and inner hair cells (IHCs) in the mammalian cochlea. Whereas Ikzf2 is necessary for OHC development, the key gene required for IHC development remains unknown. We found that deletion of Tbx2 in neonatal IHCs led to their transdifferentiation into OHCs by repressing 26.7% of IHC genes and inducing 56.3% of OHC genes, including Ikzf2. More importantly, persistent expression of Tbx2 coupled with transient Atoh1 expression effectively reprogramed non-sensory supporting cells into new IHCs expressing the functional IHC marker vGlut3. The differentiation status of these new IHCs was considerably more advanced than that previously reported. Thus, Tbx2 is essential for IHC development, and co-upregulation of Tbx2 with Atoh1 in supporting cells represents a new approach for treating deafness related to IHC degeneration.
2022-08-09 | GSE199369 | GEO
Project description:Sensory-independent Ca2+ spiking activity is crucial for the development of mammalian sensory systems. In the cochlea, spontaneous Ca2+ action potentials (APs) are present in the pre-hearing inner hair cells (IHCs), the frequency and pattern of which is modulated by ATP-dependent intercellular Ca2+ waves in the non-sensory cells. It remains unknown whether both these Ca2+-dependent signalling mechanisms in the cochlea are required for the functional maturation of the IHCs. We found that the intrinsic Ca2+ AP activity, but not that triggered by Ca2+ signalling in the non-sensory cells, regulates the maturation and maintenance of the stereociliary hair bundle in IHCs. We used a mouse model in which the potassium channel Kir2.1 is reversibly overexpressed in IHCs in vivo. Kir2.1 overexpression (Kir2.1-OE mice) prevented spontaneous Ca2+ spikes in IHCs, but not their modulation by ATP-induced signalling from non-sensory cells. Without spontaneous Ca2+ APs, mechanoelectrical transduction in IHCs disappeared prior the onset of hearing at P12 due to the progressive loss of stereocilia and their fusion. RNA-sequencing data showed that several pathways, including those involved in morphogenesis, actin-filament based processes, and Rho-GTPase signalling, were upregulated during the second postnatal week. By manipulating the in vivo expression of Kir2.1 channels, we identified the second post-natal week as the “critical point” after which spontaneous Ca2+ APs are required for proper hair bundle maintenance. We showed that the final stage of IHC maturation is finely regulated by their intrinsic electrical activity just before sound-induced sensory driven activity.
2023-01-01 | GSE215951 | GEO
Project description:In the ear, inner hair cells (IHCs) employ sophisticated glutamatergic ribbon synapses with afferent neurons to transmit auditory information to the brain. The presynaptic machinery responsible for neurotransmitter release in IHC synapses includes proteins such as the multi-C2-domain protein otoferlin and the vesicular glutamate transporter 3 (VGluT3). Yet, much of this likely unique molecular machinery remains to be deciphered. The scarcity of material has so far hampered biochemical studies which require large amounts of purified sample. We developed a subcellular fractionation workflow combined with immunoisolation of VGluT3-containing membrane vesicles, allowing for the enrichment of IHC trafficking glutamatergic organelles that are likely dominated by synaptic vesicles (SVs) of IHCs. We have characterized their protein composition in mice before and after hearing onset using mass spectrometry and confocal imaging and provide a fully annotated proteome with hitherto unidentified proteins. Despite the prevalence of IHC marker proteins across IHC maturation, the profiles of trafficking proteins differed markedly before and after hearing onset. Our study provides an inventory of the machinery associated with synaptic vesicle-mediated trafficking and presynaptic activity at IHC ribbon synapses and serves as a foundation for future functional studies.
2024-02-09 | PXD046664 | Pride
Project description:The transcriptome is the complete set of all RNA transcripts produced by the genome in a cell and reflects the genes that are being actively expressed. Transcriptome analysis is essential for understanding the genetic mechanism controlling the phenotype of a cell. Using DNA microarray technique we examined transcriptomes of 2,000 individually collected inner (IHCs) and outer hair cells (OHCs), two types of auditory sensory cells critical for hearing. Among approximately 16,645 and 17,711 transcripts considered to be expressed, 1,296 and 256 genes showed significant differential expression in IHCs and OHCs, respectively. The top ten differentially expressed genes include Slc17a8, Dnajc5b, Slc1a3, Atp2a3, Osbpl6, Slc7a14, Bcl2, Bin1, Prkd1, Map4k4 in IHCs, and Slc26a5, C1ql1, Strc, Dnm3, Plbd1, Lbh, Olfm1, Plce1, Tectb, Ankrd22 in OHCs. Many unknown sequences and non-coding RNAs were also expressed in hair cells. The differentially expressed genes underlie the genetic mechanism for unique functions of IHCs and OHCs. The total RNA was extracted from the collected pools of single outer hair cell (OHC) and inner hair cell (IHC). Their whole-genome transcriptome expression was detected using GeneChip microarray analysis. The analysis and comparison between OHC and IHC allow us to determine what genes are expressed and what genes are uniquely or differential expressed in each population.
2014-08-12 | E-GEOD-56866 | biostudies-arrayexpress
Project description:Type I spiral ganglion neurons (SGNs) convey sound information to the central auditory pathway by forming axo-somatic synapses with inner hair cells (IHCs), the primary sensory receptors of the mammalian cochlea. Although IHC ribbon synapses have been extensively studied, the molecular mechanisms regulating the structure and function of the post-synaptic density (PSD) at the SGN afferent terminals are largely unknown. Using functional, morphological, and transcriptomic approaches, we demonstrate that brain-specific angiogenesis inhibitor 1 (BAI1), encoded by the Adgrb1 gene, is required for the clustering of the glutamate AMPA receptors GluR2-4 to the SGN post-synaptic density. Adult mice expressing BAI1 lacking the N-terminal thrombospondin type 1 repeats (TRS) have functional IHC synapses but fail to transmit acoustic information to the SGNs, leading to highly raised auditory thresholds. We also found that in adult Bai1-deficient mice, despite the almost complete absence of AMPA receptors, the SGN fibres innervating the IHCs did not degenerate. RNA sequencing and western blotting also indicate that AMPA receptors are expressed in the cochlea of Bai1-deficient mice, highlights that BAI1 is involved is trafficking or anchoring GluR2-4 to the PSDs. Moreover, these results have identified novel molecular and functional mechanisms required for sound encoding at cochlear ribbon synapses.
2024-03-27 | GSE254269 | GEO
Project description:Our work describes the application of mass spectrometry-based label-free quantitative proteomics for the identification of differentially expressed proteins between different-aged cochlea. We report proteins exclusively present as well as up- and downregulated in the cochlear sensory epithelium at significant developmental stages. Additionally, we report proteins exclusively present on P3 that were recently identified in the cochlea for the first time. We use bioinformatics to provide insight on biological functions and potential primary and secondary partners of the differentially expressed proteins. This study provides the first differentially expressed proteome in the mammalian cochlea at significant developmental stages; before hearing, during the onset of hearing, and when hearing is fully developed. We believe that these results will provide insights into the function of proteins that change during development and identify potential protein biomarkers related to hearing impairments.
2018-08-29 | PXD001973 | Pride
Project description:Age-related hearing (ARHL) loss affects a large part of the human population with a major impact on our aging societies. Yet, underlying mechanisms are not understood, and no validated therapy or prevention exists. NADPH oxidases (NOX), are important sources of reactive oxygen species (ROS) in the cochlea and might therefore be involved in the pathogenesis of ARHL. Here we investigate ARHL in a mouse model. Wild type mice showed early loss of hearing and cochlear integrity, while animals deficient in the NOX subunit p22phox remained unaffected up to six months. Genes of the excitatory pathway were down-regulated in p22phox-deficient auditory neurons. Our results demonstrate that NOX activity leads to upregulation of genes of the excitatory pathway, to excitotoxic cochlear damage, and ultimately to ARHL. In the absence of functional NOXs, aging mice conserve hearing and cochlear morphology. Our study offers new insights into pathomechanisms and future therapeutic targets of ARHL.
2020-12-18 | E-MTAB-8668 | biostudies-arrayexpress
Project description:Alzheimer's disease (AD) is the most common type of dementia and is characterized by cognitive and behavioral impairment that significantly interferes with social functioning. Over the last decade, there has been an increased interest in whether sensory deficiency may be associated with the development of AD. Notably, the relationship between hearing impairment and AD is of great relevance, but still poorly understood. In this study, we found an early-onset hearing loss in 3xTgAD and 3xTgAD/Polβ+/− mouse models. The hearing assessment was measured by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) recordings. Herein, we report that both 3xTgAD and 3xTgAD/Polβ+/− mice showed increased ABR thresholds between at 16 and 32 kHz at 4 weeks of age, much earlier than any AD behavioral changes. The ABR thresholds were significantly higher in 3xTgAD/Polβ+/− mice than in 3xTgAD mice at 16 kHz, and DPOAE signals were also reduced, indicating that DNA damage may affect hearing impairment in AD. Poly ADP-ribosylation levels and protein expression of DNA damage markers increased significantly and NAD+ levels were reduced in the cochlea of 3xTgAD and 3xTgAD/Polβ+/− mice. Remarkably, we observed the downregulation of phosphoglycerate mutase 2 (PGAM2) in cochlea and a decrease in the number of synaptic ribbons in the presynaptic zones of inner hair cells in 3xTgAD/Polβ+/− mice. We also find that the activity of sirtuin 3 (SIRT3) is downregulated in cochlea, indicative of impaired mitochondrial function. Taken together, hearing impairment may be a potential early marker of AD. In addition, these findings provide new insights into the mechanism of the relationship between hearing dysfunction and AD and suggest that DNA damage in the cochlea can contributes to the development of early hearing loss of AD. The hearing assessment was measured by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) at 4 weeks of age, thereafter whole cochlea and auditory cortex tissue were collected from each mouse (WT, Polβ+/−, 3xTgAD, and 3xTgAD/Polβ+/−) and subjected to total RNA isolation to understand what metabolism-related gene expression changes in cochlea and auditory cortex.
2024-03-27 | GSE232205 | GEO
Project description:Presbycusis – age-related hearing loss – is the number one communicative disorder of our aged population. Here we analyzed gene expression for a set of GABA receptors in the cochlea of aging CBA mice using the Affymetrix GeneChip MOE430A. Functional phenotypic hearing measures distortion-product otoacoustic emission (DPOAE) amplitudes (four age groups) were made. The gene expression changes from RMA normalized microarray data (40 replicates) were first subjected to one-way ANOVA, and then linear regression was performed. In addition, the log signal ratio was converted to fold change, and selected gene expression changes were confirmed by relative real-time PCR. Major findings: expression of GABA-A receptor subunit 6was upregulated with age and hearing loss, whereas subunit 1 was repressed. In addition, GABA-A receptor associated protein like-1 and GABA-A receptor associated protein like-2 were strongly downregulated with age and hearing impairment. Lastly, gene expression measures were correlated with pathway/network relationships relevant to the inner ear using Pathway Architect, to identify key pathways consistent with the gene expression changes observed. In the study of expression changes GABA receptors in the in cochlea of young adult and aging presbycusis mice total of forty chips were used. The normal aging mice were in four groups young adults controls with good hearing (8 mice, 8 MOE430A GeneChips), Middle aged group with good hearing ( 17 mice, 17 MOE430A GeneChips), Mild Presbycusis (old) with limited hearing loss (9 mice, 9 MOE430A GeneChips) and Severe Presbycusis (old) (6 mice, 6 MOE430A GeneChips). Each Mice cochlea to each GeneChips, Samples was not pooled. The hearing potential evidence of each mouse is accompanied with each mice DPOAE amplitude.
2013-08-06 | E-GEOD-49543 | biostudies-arrayexpress
Project description:Age-related hearing impairment (ARHI), one of the most common medical conditions, is strongly heritable, yet its genetic causes remain largely unknown. We conducted a meta-analysis of GWAS summary statistics from multiple hearing-related traits in the UK Biobank (n = up to 323,978) and identified 31 genome-wide significant risk loci for self-reported hearing difficulty (p < 5e-8), of which 30 have not been reported previously at genome-wide significance. We interpreted these loci in the context of newly generated ATAC-seq and single-cell RNA-seq from cells in the mouse cochlea. Risk-associated genes were enriched for expression in cochlear epithelial and non-epithelial cells, as well as for genes related to sensory perception and known Mendelian deafness genes, supporting their relevance to auditory function. Regions of the human genome homologous to open chromatin in sensory epithelial cells from the mouse were strongly enriched for heritable risk for hearing difficulty, even after adjusting for baseline effects of evolutionary conservation and cell-type non-specific regulatory regions. Epigenomic and statistical fine-mapping most strongly supported 50 putative risk genes. Of these, at least 45 were expressed in mouse cochlea and 15 were enriched specifically in sensory hair cells. These results reveal new risk loci and risk genes for hearing difficulty and suggest an important role for altered gene regulation in the cochlear sensory epithelium.
2020-08-01 | GSE135737 | GEO