Project description:Melanocytes are important components of the inner ear’s cellular architecture. However, limited morphological research has hindered a complete understanding of inner ear function. This study characterized the morphology of inner ear melanocytes and cells often misidentified as melanocytes. Immunofluorescence, Smart-seq, transmission/field emission scanning electron microscopy, and immunoelectron microscopy were used. Cells with a “black ball” appearance in the vestibule were identified as macrophages. We examined variation in melanocytes or macrophages with age, strain, and cisplatin injury. Kir4.1 expression and the greater noise resistance observed in pigmented mice suggest potential melanocyte functions. Based on melanin distribution in Pou3f4y/- mice, we hypothesize that melanocytes migrate from the modiolus along Reissner's membrane to the stria vascularis, following a base to apex gradient. These findings provide novel ultrastructural and immunological insights into inner ear function.
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 6 control samples and 8 samples trans-tympanically injected with H flu 10e9 for 6 hours. Each sample is a pool of 4 animals
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.
Project description:In 2014, a method was introduced to differentiate mouse embryonic stem cells into inner ear vestibular-like sensory epithelia in vitro. The resulting inner ear organoids represent a potentially inexhaustible source of tissues for investigating mechanosensory hair cell development, function, and responses to ototoxic and regenerative treatments. However, there has been limited exploration into how closely the molecular characteristics of organoid-derived hair cells match those that develop in vivo. To address this gap, we have employed single-cell RNA sequencing (scRNA-seq) to generate a comprehensive atlas of inner ear organoid development at six stages, spanning the formation of definitive ectoderm to the emergence of sensory hair cells. Here, we specifically utilize our inner ear organoid atlas to define the dynamic changes in gene expression that occur during otic vesicle cell maturation into sensory epithelial supporting cells and hair cells.
Project description:The inner ear continues to grow and develop until the auditory and vestibular systems reach full maturity and all of the genes involved in this process have yet to be identified. Previous gene based analysis have primarily focused on the early developmental stages following induction and initial formation of the inner ear. The aim of this study is to identify new candidate genes for inner ear development. Microarrays were used to produce expression profiles from larval stages 56,57,58 of the Xenopus laevis inner ear. The data produced from this work represent an annotated resource that can be utilized by the Xenopus community to provide candidates for further functional analysis. Xenopus inner ears were isolated from larval animals for RNA extraction and hybridization to Affymetrix GeneChip microarrays.
Project description:Retinoblastoma gene (Rb1) is required for proper cell cycle exit in the developing mouse inner ear and its deletion in the embryo leads to proliferation of sensory progenitor cells that differentiate into hair cells and supporting cells. In the Pou4f3-Cre:Rb1 flox/flox (Rb1 cKO) inner ear, utricular hair cells differentiate and survive into adulthood whereas differentiation and survival of cochlear hair cells are impaired. To comprehensively survey the pRb pathway in the mammalian inner ear, we performed microarray analysis of Rb1 cKO cochlea and utricle. P6 or 2-month control and Rb1 cKO littermates were euthanized and the inner ear tissues were dissected. Total RNA was extracted from the pooled samples. Technical duplicates of the pooled RNA were used for microarray.
Project description:The inner ear continues to grow and develop until the auditory and vestibular systems reach full maturity and all of the genes involved in this process have yet to be identified. Previous gene based analysis have primarily focused on the early developmental stages following induction and initial formation of the inner ear. The aim of this study is to identify new candidate genes for inner ear development. Microarrays were used to produce expression profiles from larval stages 50,51,52 of the Xenopus laevis inner ear. The data produced from this work represent an annotated resource that can be utilized by the Xenopus community to provide candidates for further functional analysis.
Project description:The inner ear continues to grow and develop until the auditory and vestibular systems reach full maturity and all of the genes involved in this process have yet to be identified. Previous gene based analysis have primarily focused on the early developmental stages following induction and initial formation of the inner ear. The aim of this study is to identify new candidate genes for inner ear development. Microarrays were used to produce expression profiles from larval stages 56,57,58 of the Xenopus laevis inner ear. The data produced from this work represent an annotated resource that can be utilized by the Xenopus community to provide candidates for further functional analysis.
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.