Project description:The mammalian inner ear subserves auditory and vestibular sensations via highly specialized cells and proteins. We show that sensory hair cells (HCs) employ hundreds of uniquely or highly expressed proteins for processes involved in transducing mechanical inputs, stimulating sensory neurons, and maintaining structure and function of these post-mitotic cells. Our proteomic analysis of purified HCs extends the existing HC transcriptome, revealing undetected gene products and isoform-specific protein expression. Comparison with mouse and human databases of genetic auditory/vestibular impairments confirms the critical role of the HC proteome for normal inner ear function, providing a cell-specific pool of candidates for novel, important HC genes. Several proteins identified exclusively in HCs by proteomics and by immunohistochemistry map to human genetic deafness loci, potentially representing new deafness genes.
Project description:The vertebrate inner ear arises from a pool of progenitors with the potential to give rise to all the sense organs and cranial ganglia of the head1-6. Here we explore the molecular mechanisms that control ear specification from these progenitors. Using a multi-omics approach combined with loss-of-function experiments we identify a core transcriptional circuit that imparts ear identity, along with non-coding elements that integrate this information. This analysis places the transcription factor Sox8 at the top of the ear determination network. Introducing Sox8 into cranial ectoderm not only converts non-ear cells into ear progenitors, but also activates the cellular programmes for ear morphogenesis and neurogenesis. Thus, Sox8 emerges as a master regulator of ear identity and may be a key factor for sense organ cell reprogramming.
Project description:The vertebrate inner ear arises from a pool of progenitors with the potential to give rise to all the sense organs and cranial ganglia of the head1-6. Here we explore the molecular mechanisms that control ear specification from these progenitors. Using a multi-omics approach combined with loss-of-function experiments we identify a core transcriptional circuit that imparts ear identity, along with non-coding elements that integrate this information. This analysis places the transcription factor Sox8 at the top of the ear determination network. Introducing Sox8 into cranial ectoderm not only converts non-ear cells into ear progenitors, but also activates the cellular programmes for ear morphogenesis and neurogenesis. Thus, Sox8 emerges as a master regulator of ear identity and may be a key factor for sense organ cell reprogramming.
Project description:Exosomes are nanovesicles involved in intercellular communications. They are released by a variety of cell types; however, their presence in the inner ear has not been described in the literature. The aims of this study were to determine if exosomes are present in the inner ear and, if present, characterize the changes in their protein content in response to ototoxic stress. In this laboratory investigation, inner ear explants of 5-day-old Wistar rats were cultured and treated with either cisplatin or gengentamicin. Exosomes were isolated using ExoQuick, serial centrifugation, and mini-column methods. Confirmation and characterization of exosomes was carried out using transmission electron microscopy (TEM), ZetaView, BCA protein analysis, and proteomics. Vesicles with a typical size distribution for exosomes were observed using TEM and ZetaView. Proteomic analysis detected typical exosome markers and markers for the organ of Corti. There was a statistically significant reduction in the exosome protein level and number of particles per cubic centimeter when the samples were exposed to ototoxic stress. Proteomic analysis also detected clear differences in protein expression when ototoxic medications were introduced. This is the first report describing exosomes derived from the inner ear. Because these exosomes varied in number and protein composition when the inner ear was exposed to ototoxic stress, the exciting possibility exists that they might be used as biomarkers to monitor inner ear function.