Chronic inflammation directs an olfactory stem cell functional switch from neuroregeneration to immune defense (bulk RNA-Seq)
Ontology highlight
ABSTRACT: Although the olfactory mucosa possesses long-lived horizontal basal stem cells (HBCs) and remarkable regenerative capacity, the function of human olfactory neuroepithelium is significantly impaired in the setting of chronic rhinosinusitis. Here we used RNA sequencing to analyze the transcriptional profile of mouse HBCs in a chronic inflammatory milieu. Global gene expression analysis in inflamed HBCs reveals broad upregulation of NF-κB-regulated cytokines and chemokines accompanied by enhancement of “stemness”-related transcription factors. Our results provide evidence of basal stem cells as direct participants in the progression of chronic inflammation and identify a concomitant functional switch away from neuroregeneration.
Project description:We report bulk RNAseq of in vitro cultured horizontal basal cells, and in vivo isoalted respiratory basal cells of the murine olfactory epithelium, and compared their profiles with pre-existing bulk RNAseq of in vivo isolated HBCs and single cell RNAseq of in vivo HBCs.
Project description:Wild-type horizontal basal cells (HBCs) from mouse olfactory epithelium were profiled using single-cell ATAC-seq (10x Genomics v2) to identify regions of accessible chromatin in individual cells before and 24 hours after acute injury.
Project description:The Vomeronasal organ (VNO) is a part of the accessory olfactory system, which is responsible for detecting pheromones, chemical factors that trigger a spectrum of sexual and social behaviors. The vomeronasal epithelium (VNE) shares several features with the epithelium of the main olfactory epithelium (MOE). However, it is a distinct neuroepithelium populated by chemosensory neurons that differ from the olfactory sensory neurons (OSNs) in cellular structure, receptor expression, and connectivity. The vomeronasal organ of rodents comprises a sensory epithelium and a thin nonsensory epithelium that morphologically resembles the respiratory epithelium. Sox2-positive cells have been previously identified as the stem cell population that gives rise to neuronal progenitors in MOE and VNE. In addition to these, the MOE also comprises p63 positive horizontal basal cells (HBCs), a second pool of quiescent stem cells that become active in response to injury. Immunolabeling against the transcription factor p63, Keratin-5 (Krt5), Krt14 and Krt5Cre tracing experiments highlighted the existence of horizontal basal cells distributed along the basal lamina of the VNO forming from progenitors along the basal lamina oft the marginal zones. Moreover, these experiments revealed that the NSE of rodents is, like the respiratory epithelium, a stratified epithelium where the p63/Krt5+ basal cells self-replicate and give rise to the apical columnar cells facing the lumen of the VNO.
Project description:RNAseq analysis of uninjured vs 18hpl injured HBCs show heterogeneous modulation of pathways associated with quiescent stem cell activation. HBCs are the trp63 expressing, quiescent basal stem cell in the olfactory epithelium.
Project description:Unlike most of the adult nervous system, the olfactory epithelium (OE) can regenerate neurons lost during normal homeostasis or after injury. This life-long regeneration is propagated by two populations of stem cells, the actively proliferating globose basal cells (GBCs) and the dormant horizontal basal cells (HBCs). HBCs only activate and contribute to epithelial regeneration in the context of severe injury, and this activation is mediated by the loss of the transcription factor Tp63. While the HBC differentiation trajectories that occur after activation have been described with lineage tracing and single-cell RNA seq experiments, the immediate consequences of injury on HBC gene expression and fate commitment have not been explored. We present an in vitro model of the acute activation process for HBCs in response to treatment with phorbol 12-myristate 13-acetate (PMA) to explore the molecular underpinnings of these early activation events. We find that treating HBCs with PMA induces the rapid degradation of TP63, and we find that this effect is partially reversed when cells are allowed to recover in maintenance media. Using bulk RNA sequencing we found that PMA-treated HBCs pass through various stages of acute activation identifiable by specific gene regulatory signatures. These transcriptomic phases are associated with varying degrees of plasticity with regards to activated HBCs ability to engraft in transplant models.
Project description:Histones, major carriers of epigenetic information, play critical roles in regulating gene expression patterns and cell fate decisions. While asymmetric histone inheritance has been shown to regulate distinct cell fates in Drosophila adult stem cells, its relevance in mammals remains unclear. In this study, we investigated cell division modes and histone inheritance patterns in horizontal basal cells (HBCs) of the mouse olfactory epithelium following injury. We found that approximately 40% of telophase HBCs show asymmetric division, with a corresponding asymmetric segregation of histone H4. In primary cultured HBCs, we observed asymmetric cell division accompanied by asymmetric distribution of histones, including H4, H3, and H3.3, but not H2A-H2B. Asymmetric histone segregation leads to asymmetric association of a key ‘stemness’ transcription factor p63 and asynchronous transcription re-initiation during mitotic exit. Single-cell RNA sequencing of paired daughter cells further revealed asymmetric cell fate priming in cultured HBCs. Disruption of asymmetric cell division abolished asymmetric transcription re-initiation, asymmetric histone inheritance in culture HBCs and further caused regeneration defects in OE. These findings reveal the conservation of asymmetric histone inheritance in mammalian adult stem cells and highlight its biological significance in tissue regeneration.
Project description:The olfactory neuroepithelium serves as a sensory organ for odors and forms part of the nasal mucosal barrier. Olfactory sensory neurons are surrounded and supported by epithelial cells. Among them, microvillous cells (MVCs) are strategically positioned at the apical surface, but their specific functions are enigmatic and their relationship to the other specialized epithelial cells, particularly the solitary chemosensory cell family, is unclear. Here, we establish that the family of MVCs comprises tuft cells and ionocytes in both mice and humans. Integrating analysis of the respiratory and olfactory epithelia, we define the unique receptor expression of TRPM5+ tuft-MVCs compared to Gɑ-gustducinhigh respiratory tuft cells and characterize a new population of glandular DCLK1+ tuft cells. To establish how allergen sensing by tuft-MVCs might direct olfactory mucosal responses, we employed an integrated single-cell transcriptional and protein analysis. Inhalation of Alternaria induced mucosal epithelial effector molecules including Chil4, and a distinct pathway leading to proliferation of the quiescent olfactory horizontal basal stem cell (HBC) pool, both triggered in the absence of olfactory apoptosis. While the Chil4 pathway was dependent on STAT6 signaling and innate lymphocytes, neither were required for HBC proliferation. Alternaria- and ATP- elicited HBC proliferation was dependent on tuft-MVCs, establishing these specialized epithelial cells as regulators of olfactory stem cell responses. Together our data provide high resolution characterization of nasal tuft cell heterogeneity and uncover a novel function for TRPM5+ tuft-MVCs in directing the olfactory mucosal response to allergens.
Project description:We used trasncriptional profiling of fluorescent activated cell sorting (FACS) purified ICAM1-positive and negative cells from the olfactory epithelium (OE) of three-week old mice to identify genes enriched in the horizontal basal cells.
Project description:The lineage of wild-type horizontal basal cells (HBC) stem cells from the olfactory epithelium were profiled by single-cell RNA-Seq (10X v3 chemistry) to identify differences in aged versus not-aged adult stem cells mRNA expression profiles