Project description:We use closely-related Drosophila species to understand mechanosensation and how hearing as a form of mechanosensation drives reproductive isolation and evolution. In particular, we performed RNA-seq to obtain the Johnston's Organ transcriptomes of six closely-related Drosophila species, namely, D.melanogaster, D.yakuba, D.pseudoobscura and D.persimilis. Application of the Ornstein-Uhlenbeck model identified gene expression changes between the species' auditory structures. Motif discovery ( i-cisTarget and iRegulon) in differentially expressed genes in the oobscura group and melanogaster group on these transcriptomes identified thetranscription factor Hr39 as important for auditory differences among species. Hr39 is a nuclear hormone receptor important in song production and spermathecae development. Futher functional analyses Hr39 and many of its downstream targets are expressed in Johnston's Organ neurons. Hr39 mutants show sexually dimorphic defects in auditory mechanics and compound action potentials. These results indicate that Hr39 and its downstream regulon have a key role in Drosophila courtship behavior as a mechanism of reproductive isolation and evolution.
Project description:We characterized the proteome of the auditory brainstem of a chick embryo on embryonic day 13, when apoptosis occurs in auditory nuclei. We identified caspase substrates by searching the peptidome for peptides C-terminal to caspase-typical cleavage sites.
Project description:Sound localization requires extremely precise development of auditory brainstem circuits, the molecular mechanisms of which are largely unknown. We previously demonstrated a novel requirement for non-apoptotic activity of the protease caspase-3 in chick auditory brainstem development. Here, we used mass spectrometry to identify proteolytic substrates of caspase-3 during chick auditory brainstem development. Functional annotation analysis revealed that our caspase-3 substrates were enriched more than two-fold for proteins associated with extracellular vesicles (EVs), membrane-bound nanoparticles that function in intercellular communication. The proteome of EVs isolated from the auditory brainstem contained caspase-3 and was highly enriched for the caspase-3 substrates identified here. Additionally, we identified two caspase-3 substrates with known functions in axon guidance, namely Neural Cell Adhesion Molecule (NCAM) and Neuronal-glial Cell Adhesion Molecule (Ng-CAM), that were found in auditory brainstem EVs and expressed in the auditory pathway alongside cleaved caspase-3. Taken together, these data suggest a novel developmental mechanism whereby caspase-3 influences auditory brainstem circuit formation through the proteolytic cleavage of EV proteins.
Project description:Hemizygous ato[1]/Df(3R)p[13] null mutants lack Johnston organ (JO) in their 2nd antennal segment. We screened for genes that are expressed in JO by comparing the 2nd antennal segment transcriptomes between ato[1]/Df(3R)p[13] mutants and balanced Df(3R)p[13]/TM3 and ato[1]/TM3 controls. To assess transcriptomes, we isolated the 2nd antennal segments of ~50 flies per strain and extracted their total RNA. Because about half of the JO cells are sensory neurons, we also isolated RNA from the brains of ato[1]/TM3 controls to delineate neuronal JO genes. cRNA was hybridized to Affymetrix Drosophila Genome 2.0 arrays. For each experiment, three biological replicates were run.
Project description:Spiral ganglion neurons (SGNs) and the associated components of the auditory nerve are primary carriers of auditory information from hair cells to the brain. Loss of SGNs occurs with many pathological conditions, resulting in permanent sensorineural hearing loss. Neural stem/progenitors (NSPs) have been well-characterized in several locations of adult brain and retina. However, it is unclear whether NSPs are present in the adult auditory nerve. Here we examined the self-renewal potential of the adult auditory nerve using ouabain application as a well-established mouse model of acute SGN injury. The observed increase in cell proliferation, alteration in enchromatin/heterochromatin ratio and down-regulation of histone deacetylase expression in glial cells suggest that the quiescent glial cells convert to an activated state after SGN degeneration. This was further confirmed by global gene expression analysis of injured auditory nerves, which showed up-regulation of numerous neurogenesis- and/or development-associated genes shortly after ouabain exposure. These genes include molecular markers commonly used for the identification of NSPs. Under a strict culture regimen, auditory nerve-derived cells of adult mouse ears gave rise to neurospheres, suggesting that multipotent NSPs are present in adult cochlear nerve. Neurosphere assays on Sox2 transgenic mice revealed that Sox2+ glial cells are the source for NSPs. Our data also showed that acute injury or hypoxia enhances neurosphere formation. Taken together, our study revealed that glial cells of adult cochlea exhibit several NSP characteristics, and hence these mature non-neuronal cells may be important targets for promoting self-repair of degenerative auditory nerves. Auditory nerves were removed from the temporal bones of adult CBA/CaJ mice, aged 8 to 12 weeks. Tissues were either collected and used directly as the tissue samples or dissociated and used for the cell culture samples. Dissociated auditory nerve cells were propagated and grown to full confluency (5-7 days), constituting the cultured cell samples. For neurosphere samples, growth medium was changed to neurosphere formation medium and the cells were cultured for an additional 12 days. All samples were prepared in triplicate (n=3).
Project description:Spiral ganglion neurons (SGNs) and the associated components of the auditory nerve are primary carriers of auditory information from hair cells to the brain. Loss of SGNs occurs with many pathological conditions, resulting in permanent sensorineural hearing loss. Neural stem/progenitors (NSPs) have been well-characterized in several locations of adult brain and retina. However, it is unclear whether NSPs are present in the adult auditory nerve. Here we examined the self-renewal potential of the adult auditory nerve using ouabain application as a well-established mouse model of acute SGN injury. The observed increase in cell proliferation, alteration in enchromatin/heterochromatin ratio and down-regulation of histone deacetylase expression in glial cells suggest that the quiescent glial cells convert to an activated state after SGN degeneration. This was further confirmed by global gene expression analysis of injured auditory nerves, which showed up-regulation of numerous neurogenesis- and/or development-associated genes shortly after ouabain exposure. These genes include molecular markers commonly used for the identification of NSPs. Under a strict culture regimen, auditory nerve-derived cells of adult mouse ears gave rise to neurospheres, suggesting that multipotent NSPs are present in adult cochlear nerve. Neurosphere assays on Sox2 transgenic mice revealed that Sox2+ glial cells are the source for NSPs. Our data also showed that acute injury or hypoxia enhances neurosphere formation. Taken together, our study revealed that glial cells of adult cochlea exhibit several NSP characteristics, and hence these mature non-neuronal cells may be important targets for promoting self-repair of degenerative auditory nerves.
Project description:External auditory canal squamous cell carcinoma (EACC) is very rare, only accounting for two thousandth of the head and neck cancer. However, the development mechanism of EACC remains unknown. By using gene expression microarray analysis, we aimed to find differentially expressed genes involved in ESCC development. We identified a wide spectrum of molecular signatures in EACC, including mRNA and lncRNA. The present study systematically analyzed the expression of mRNA and lncRNA in squamous cell carcinoma of the external auditory canal and normal external auditory canal tissues. We detect the transcriptomic changes between squamous cell carcinoma of the external auditory canal and normal external auditory canal tissues to identify potential tumor biomarkers in squamous cell carcinoma of the external auditory canal.
Project description:We performed transcriptional profiling of sexed whole adults and mixed sex embryos of eight Drosophila species. These data were used in a comparative transcriptomics analysis of multiple Drosophila species to define functional elements conserved throughout the Drosophila genus.