Project description:We report RNA sequencing of single olfactory neurons from mouse olfactory epithelium in developmental progression from progenitors to precursors to immature neurons to mature neurons. Most mature neurons expressed only one of ~ 1000 odorant receptor genes (Olfrs) at high levels, whereas many immature neurons expressed low levels of multiple Olfrs. Investigating expression of odorant receptors genes in mouse olfactory sensory neurons during development.
Project description:The objectives of this study were to use unilateral naris occlusion (UNO) in order to characterize the effects of olfactory deprivation on the relative abundance of newly generated olfactory sensory neurons that express specific odorant receptors.
Project description:The modified DNA base 5-hydroxymethylcytosine (5hmC) is enriched in neurons where it may contribute to gene function and cellular identity. To address this issue in an in vivo neuronal population, we assessed the patterning, stability, and function of the base within gene bodies in olfactory sensory neurons. We find that gene body 5hmC linearly correlates with transcriptional output and is stable in fully mature neurons and those lacking de novo methyltransferase activity. Overexpression of Tet3, which oxidizes methylated cytosines (5mC) to 5hmC, markedly alters gene body 5hmC levels and provides evidence that 5hmC facilitates transcription. This manipulation disrupts olfactory receptor expression and the targeting of axons to the olfactory bulb, key molecular and anatomical features of the olfactory system that are necessary for proper physiology. Our results support a direct, positive and physiologically significant role for gene body 5hmC in transcriptional elongation and the maintenance of cellular identity independent of its function as an intermediate to demethylation. We assessed the role of 5hmC in mature olfactory sensory neurons by assessing 5hmC levels in 2 month old neurons, olfactory epithelia lacking Dnmt3a, and mOSNs overexpressing Tet3. To determine genome-wide levels of 5hmC, we performed DNA immunoprecipitation coupled to Illumina sequencing. To determine transcript levels, we prepared and sequenced rRNA-depleted cDNA libraries.
Project description:Expression profiling of mRNA abundance in the adult mouse olfactory epithelium during replacement of OSNs forced by the bilateral ablation of the olfactory bulbs. The experiment was done on 6 week old male C57Bl/6 mice. Olfactory epithelium tissue samples were collected on days 1, 5, and 7 after bulbectomy. The cellular processes activated by bulbectomy include apoptosis of mature olfactory sensory neurons, infiltration of macrophages and dendritic cells, stimulation of proliferation of basal cell progenitors, and differentation of new sensory neurons.
Project description:A reduced sense of smell has been reported in people with cystic fibrosis (CF). These olfactory defects have largely been attributed to secondary manifestations of the disease, such as inflammation of the nasal mucosa. Here we show that CFTR, the gene responsible for CF, is expressed in proliferating olfactory human cells and that newborn CFTR null pigs display ultrastructural abnormalities in the olfactory epithelium and olfactory bulbs. In the absence of CFTR, olfactory sensory neurons still produce odor-evoked activity, but mutant animals display defective odor-guided suckling behavior after birth. Consistent with epithelial changes, we found a reduced expression of genes implicated in cell cycle and development in globose basal cells (GBCs), the neurogenic progenitor cells in the olfactory epithelium. Targeted sequencing revealed enhanced CFTR expression in the subpopulation of GBCs that is actively proliferating. Furthermore, CFTR loss caused a global reduction in the number of sensory neurons and altered olfactory receptors expression. Our findings highlight a previously unknown role of CFTR in olfactory system function by regulating progenitor cell proliferation in the olfactory epithelium.
Project description:A reduced sense of smell has been reported in people with cystic fibrosis (CF). These olfactory defects have largely been attributed to secondary manifestations of the disease, such as inflammation of the nasal mucosa. Here we show that CFTR, the gene responsible for CF, is expressed in proliferating olfactory human cells and that newborn CFTR null pigs display ultrastructural abnormalities in the olfactory epithelium and olfactory bulbs. In the absence of CFTR, olfactory sensory neurons still produce odor-evoked activity, but mutant animals display defective odor-guided suckling behavior after birth. Consistent with epithelial changes, we found a reduced expression of genes implicated in cell cycle and development in globose basal cells (GBCs), the neurogenic progenitor cells in the olfactory epithelium. Targeted sequencing revealed enhanced CFTR expression in the subpopulation of GBCs that is actively proliferating. Furthermore, CFTR loss caused a global reduction in the number of sensory neurons and altered olfactory receptors expression. Our findings highlight a previously unknown role of CFTR in olfactory system function by regulating progenitor cell proliferation in the olfactory epithelium.
Project description:Recognition of environmental cues is essential for the survival of all organisms. Precise transcriptional changes occur to enable the generation and function of the neural circuits underlying sensory perception. To gain insight into these changes, we generated single-cell transcriptomes of Drosophila olfactory receptor neurons (ORNs), thermosensory and hygrosensory neurons from the third antennal segment at an early developmental and adult stage. We discovered that ORNs maintain expression of the same olfactory receptors across development. Using these receptors and computational approaches, we matched transcriptomic clusters corresponding to anatomically and physiologically defined neuronal types across multiple developmental stages. Cell-type-specific transcriptomes, in part, reflected axon trajectory choices in early development and sensory modality in adults. Our analysis also uncovered type specific and broadly expressed genes that could modulate adult sensory responses. Collectively, our data reveal important transcriptomic features of sensory neuron biology and provides a resource for future studies of their development and physiology.
Project description:This project’s aim was to compare the transcriptional profiles of olfactory sensory neurons in Drosophila melanogaster in order to identify novel genes that specify neuron-specific functions/phenotypes or may otherwise be involved in the development of the olfactory system. The isolation of sufficient numbers of intact olfactory sensory neurons (OSN) from the antenna of Drosophila melanogaster has so far limited single-cell transcriptomic approaches being applied to the adult fly antenna. Targeted DamID (TaDa) provides an alternative approach for profiling transcriptional activity in a cell-specific manor that bypasses the need for isolating OSN. Using the Gal4/UAS system, we applied TaDa to seven OSN populations and compared differences in Pol II occupancy for genes across these datasets.
Project description:This experiment studies the gene expression in the mature olfactory sensory neurons and the intermidiate neuronal progenitors in the olfactory epithelia during the critical period. Mature olfactory sensory neurons from OMP-GFP mice and intermediate neuronal progenitors in the olfactory epithelia from Neurog1-GFP mice were FACS purified. PolyA RNA profiles at P2, P3, P7, P9, and P16 were generated by RNA-Seq.