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:Objective: Otitis media is known to alter expression of cytokine and other genes in the mouse middle ear and inner ear. However, whole mouse genome studies of gene expression in otitis media have not previously been undertaken. Ninety-nine percent of mouse genes are shared in the human, so these studies are relevant to the human condition. Methods: To assess inflammation-driven processes in the mouse ear, gene chip analyses were conducted on mice treated with trans-tympanic heat-killed Hemophilus influenza using untreated mice as controls. Middle and inner ear tissues were separately harvested at 6 hours, RNA extracted, and samples for each treatment processed on the Affymetrix 430 2.0 Gene Chip for expression of its 34,000 genes. Results: Statistical analysis of gene expression compared to control mice showed significant alteration of gene expression in 2,355 genes, 11% of the genes tested and 8% of the mouse genome. Significant middle and inner ear upregulation (fold change >1.5, p<0.05) was seen in 1,081 and 599 genes respectively. Significant middle and inner ear downregulation (fold change <0.67, p<0.05) was seen in 978 and 287 genes respectively. While otitis media is widely believed to be an exclusively middle ear process with little impact on the inner ear, the inner ear changes noted in this study were numerous and discrete from the middle ear responses. This suggests that the inner ear does indeed respond to otitis media and that its response is a distinctive process. Numerous new genes, previously not studied, are found to be affected by inflammation in the ear. Conclusion: Whole genome analysis via gene chip allows simultaneous examination of expression of hundreds of gene families influenced by inflammation in the middle ear. Discovery of new gene families affected by inflammation may lead to new approaches to the study and treatment of otitis media. There are 8 control samples and 9 samples trans-tympanically injected with H flu 10e9 for 6 hours. Each sample is from a single animal.