Literature context: Sox2 eBioscience 14-9811-82 RRID:AB_11219471 Rat
The olfactory epithelium (OE) of vertebrates is a highly regenerative neuroepithelium, maintained under normal condition by a population of stem and progenitor cells - globose basal cells (GBCs) that also contribute to epithelial reconstitution after injury. However, aging of the OE often leads to neurogenic exhaustion - the disappearance of both GBCs and olfactory sensory neurons (OSNs). Aneuronal tissue may remain as olfactory, with an uninterrupted sheet of apically arrayed microvillar-capped sustentacular cell, or may undergo respiratory metaplasia. We have generated a transgenic mouse model for neurogenic exhaustion using OMP-driven Tet-off regulation of the A subunit of Diphtheria toxin such that the death of mature OSNs is accelerated. As early as 2 months of age the epithelium of transgenic mice, regardless of sex, recapitulates what is seen in the aged OE of humans and rodents. Areas of the epithelium completely lack neurons and GBCs, while the horizontal basal cells, a reserve stem cell population, show no evidence of activation. Surprisingly, other areas that were olfactory undergo respiratory metaplasia. The impact of accelerated neuronal death and reduced innervation on the olfactory bulb (OB) is also examined. Constant neuronal turnover leaves glomeruli shrunken and impacts the dopaminergic interneurons in the periglomerular layer. Moreover, the acceleration of OSN death can be reversed in those areas where some GBCs persist. However, the projection onto the OB recovers incompletely and the reinnervated glomeruli are markedly altered. Thus, the capacity for OE regeneration is tempered when GBCs disappear.SIGNIFICANCE STATEMENTA large percentage of humans lose or suffer a significant decline in olfactory function as they age. Consequently, quality of life suffers, and safety and nutritional status are put at risk. With age, the OE apparently becomes incapable of fully maintaining the neuronal population of the epithelium despite its well-known capacity for recovering from most forms of injury when younger which may contribute to age-related olfactory loss. Efforts to identify the mechanism by which olfactory neurogenesis becomes exhausted with age require a powerful model for accelerating age-related tissue pathology. The current OMP-tTA;TetO-DTA transgenic mouse model, in which olfactory neurons die when they reach maturity and accelerated death can be aborted to assess the capacity for structural recovery, satisfies that need.
Literature context: 4-9811-82; RRID:AB_11219471 hamster anti-Pdpn Developmental
Basal cells (BCs) are p63-expressing multipotent progenitors of skin, tracheoesophageal and urinary tracts. p63 is abundant in developing airways; however, it remains largely unclear how embryonic p63+ cells contribute to the developing and postnatal respiratory tract epithelium, and ultimately how they relate to adult BCs. Using lineage-tracing and functional approaches in vivo, we show that p63+ cells arising from the lung primordium are initially multipotent progenitors of airway and alveolar lineages but later become restricted proximally to generate the tracheal adult stem cell pool. In intrapulmonary airways, these cells are maintained immature to adulthood in bronchi, establishing a rare p63+Krt5- progenitor cell population that responds to H1N1 virus-induced severe injury. Intriguingly, this pool includes a CC10 lineage-labeled p63+Krt5- cell subpopulation required for a full H1N1-response. These data elucidate key aspects in the establishment of regionally distinct adult stem cell pools in the respiratory system, potentially with relevance to other organs.
Literature context: her Scientific Cat# 14-9811-82, RRID:AB_11219471 1:200
During gastrulation epiblast cells exit pluripotency as they specify and spatially arrange the three germ layers of the embryo. Similarly, human pluripotent stem cells (PSCs) undergo spatially organized fate specification on micropatterned surfaces. Since in vivo validation is not possible for the human, we developed a mouse PSC micropattern system and, with direct comparisons to mouse embryos, reveal the robust specification of distinct regional identities. BMP, WNT, ACTIVIN and FGF directed mouse epiblast-like cells to undergo an epithelial-to-mesenchymal transition and radially pattern posterior mesoderm fates. Conversely, WNT, ACTIVIN and FGF patterned anterior identities, including definitive endoderm. By contrast, epiblast stem cells, a developmentally advanced state, only specified anterior identities, but without patterning. The mouse micropattern system offers a robust scalable method to generate regionalized cell types present in vivo, resolve how signals promote distinct identities and generate patterns, and compare mechanisms operating in vivo and in vitro and across species.
Literature context: anti-Sox2 eBioscience #14-9811 RRID:AB_11219471 1:100
Despite a robust capacity for adult neurogenesis in the olfactory epithelium (OE), olfactory sensory losses are common. Identification of mechanisms regulating adult OE neurogenesis is, therefore, of interest. MicroRNAs (miRNAs) are broadly important in regulating vertebrate neurodevelopment, and are required in embryonic olfactory differentiation. We report here that a panel of miRNAs is differentially expressed by either progenitor or progeny cells in the regenerating mouse OE. Progenitor cells were purified from lesioned OE based on c-Kit expression, and miRNA expression was assayed in c-Kit (+) and c-Kit (-) cell populations. 28 miRNAs were significantly downregulated by at least 4 fold in the c-Kit (+) fraction, which marks the globose basal progenitor cell population. In addition, 10 miRNAs were upregulated in these basal cells. MiR-486, the most strongly downregulated miRNA identified, was further characterized to verify results. MiR-486 expression was confirmed in the c-Kit (-) OE layers using in situ hybridization. As a functional assay, over-expression of miR-486 in purified c-Kit (+) basal cell cultures resulted in a reduction in neurogenesis, consistent with a possible negative feedback regulatory model. Our data provide new insights regarding miRNA expression and function during adult OE neurogenesis, and identify candidate miRNAs warranting further study.