Project description:In order to determine the regulators of outer hair cell postnatal maturation, we utilized the RiboTag mouse model to perform a detailed transcriptomic analysis of outer hair cells at five postnatal developmental time points: P8, P14, P28, 6 weeks (6wk) and 10 weeks (10wk). This analysis resulted in consistent enrichment of outer hair cell expressed genes in the immunoprecipitated RNA compared to whole cochlear input RNA from each time point. Using transcription factor binding motif prediction on a set of defined outer hair cell enriched genes, we further use this dataset to identify the helios transcription factor as a regulator of the postnatal outer hair cell transcriptome.
Project description:Given the potential role of the helios transcription factor in postnatal outer hair cell gene regulation indicated by our RiboTag translatome analyses, our next goal was to identify and validate genes that are regulated by helios in outer hair cells by performing RNA-seq on P8 cello mutant animals compared to wild-type littermates.
Project description:To investigate the translatome of postnatal precursors of the V-SVZ cultured as neurospheres, we employed RiboTag analysis We performed RiboTag analysis on precursors derived from NestinCreERT2;RPL22HA/HA animals using specific anti-Hemagluttinin antibodies versus non-specific IgG controls
Project description:To further understand the biological properties of hair cells of the mammalian cochlea, we examined the transcriptome of adult inner and outer hair cells. Morphologically distinct inner and outer hair cells were isolated from the organ of Corti from adult CBA/J mice. One thousand inner and outer hair cells were separately collected for each biological replicate, using the suction pipette technique. RNA sequencing of two biological replicates of IHCs and three biological replicates of OHCs, each with two technical repeats, was performed. The resulting sequenced reads were mapped. Comparisons between inner and outer hair cells allow identification of enriched genes, as well as differentially expressed genes that result in cellular specialization. Our dataset provides an extensive resource for understanding the molecular mechanisms underlying morphology, function, and pathology of adult mouse inner and outer hair cells.
Project description:In order to identify the transcriptional cascade downstream of the GFI1 repressor in inner ear hair cells, we performed a RiboTag-based expression analysis of Gfi1cre/cre mutant hair cells compared to their heterozygous controls. Through this analysis, we identified a significant downregulation of genes involved in normal hair cell development and function within the mutant hair cells, suggesting that in the absence of GFI1, the hair cells undergo a maturation arrest. Furthermore, the Gfi1 deficient hair cells displayed a significant upregulation of genes involved in neurodifferentiation and neuronal function.
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.
Project description:Analysis of Sertoli and Leydig cell “translatome” utilizing an in vivo ribosome tagging strategy (RiboTag) that allows a detailed and physiologically relevant characterization of the polysome-associated mRNAs in vivo. Although progress has been made in the identification of specific transcripts that are translated in Sertoli and Leydig cells and their response to hormones, efforts to expand these studies have been restricted by technical hurdles. Our analysis identified all previously characterized Leydig and Sertoli cell-specific markers and identified in a comprehensive manner novel markers of Leydig and Sertoli cells; the translational response of these two cell types to gonadotropins or testosterone was also investigated. Leydig cell-specific (Cyp17iCre: RiboTag) and Sertoli cell-specific (AMH-Cre: RiboTag) RiboTag mice were obtained by crossing RiboTag homozygous mice with Cyp17iCre or AMH-Cre mice. For in vivo LH treatment experiments, mice were injected with the GnRH antagonist acyline for 4 days before a single injection of purified human LH. After treatment, testes were homogenized and polysomes were immunoprecipitated by utilizing an anti-HA antibody. RNA was extracted, labelled, and hybridized to Mouse Gene ST 1.0 arrays.
Project description:Transcriptome profiling is widely used to infer functional states of specific cell types, as well as their responses to stimuli, to define contributions to physiology and pathophysiology. Focusing on microglia, the brain macrophages, we report here a side-by-side comparison of classical cell sort-based transcriptome sequencing and the ‘RiboTag’ method that avoids cell retrieval from tissue context and yields translatome sequencing information. Conventional whole cell microglia transcriptomes were found to be significantly tainted by artifacts induced by tissue-dissociation, cargo contaminations and transcripts sequestered from ribosomes. Conversely, our data highlight the added value of RiboTag profiling to assess the accuracy of Cre transgenic mice. Collectively, this study indicates method-based biases, reveals observer effects and establishes RiboTag-based translatome profiling as a valuable complement to standard sort-based profiling strategies.
Project description:Local mRNA translation mediates the adaptive responses of axons to extrinsic signals but direct evidence that it occurs in mammalian CNS axons in vivo is scant. We developed an axon-TRAP-RiboTag approach in mouse that allows deep-sequencing analysis of ribosome-bound mRNAs in the retinal ganglion cell axons of the developing and adult retinotectal projection in vivo. The embryonic-to-postnatal axonal translatome comprises an evolving subset of enriched genes with axon-specific roles suggesting distinct steps in axon wiring, such as elongation, pruning and synaptogenesis. Adult axons, remarkably, have a complex translatome with strong links to axon survival, neurotransmission and neurodegenerative disease. Translationally co-regulated mRNA subsets share common upstream regulators, and novel sequence elements generated by alternative splicing that promote axonal mRNA translation. Our results indicate that intricate regulation of compartment-specific mRNA translation in mammalian CNS axons supports the formation and maintenance of neural circuits in vivo. The profiling of ribosome-bound mRNAs in mouse retinal ganglion cell axons at 4 different developmental stages