Project description:In the context that HOX mutant mice have profound deficits in airway branching morphogenesis, we asked whether the positional identity of HOX genes is maintained in the epithelium of the adult human tracheobronchial tree and if so, whether these positional differences are embedded in the stem/progenitor population derived from nonbranching vs branching airways. We found that 10 of 39 HOX genes are expressed in varying degrees in the nonbranching (trachea) or branching (large and small airways) human airway epithelium. Strikingly, HOXB2 and B3 were highly expressed in the trachea epithelium, but barely detectable in the branching airway epithelium. This difference in HOXB2 and B3 gene expression was embedded in the airway basal cell stem/progenitor population isolated from the trachea vs branching airways, and maintained during differentiation in vitro. Finally, HOXB2 and B3 expressions in the trachea vs branching airways correlated with the expression of a variety of other transcription and growth factors related to branching morphogenesis. The finding that the adult human airway epithelium expresses some HOX genes in a positional manner, with differences embedded in the transcriptomes of airway epithelial stem/progenitor cells, has implications for the use of stem/progenitor cells for applications relevant to lung regeneration.
Project description:Nf-kB activity is associated with the key pathological features of chronic respiratory diseases including epithelial remodelling, excess mucous production, and submucosal gland hyperplasia. However, the role of Nf-kB activity in airway epithelial differentiation remains controversial. In the present study we demonstrate that Nf-kB adaptor protein Myd88 deficiency promotes increased airway submucosal gland abundance and abnormal epithelial differentiation in proximal adult airways. Abnormal airway differentiation was not developmentally determined, became exacerbated following acute lung injury, and did not involve altered epithelial proliferation or apoptosis. Instead, we demonstrate that tracheal Myd88 deficiency promotes upregulation of a unique gene expression profile that includes activation of alternate, Myd88-independent Nf-kB signalling. Finally, we show that these effects are not intrinsically maintained in vitro using an air-liquid interface epithelial culture. This finding indicates that Myd88 deficiency promotes adult airway remodelling by regulating non-epithelial, non-cell autonomous Nf-kB activity.
Project description:Nf-kB activity is associated with the key pathological features of chronic respiratory diseases including epithelial remodelling, excess mucous production, and submucosal gland hyperplasia. However, the role of Nf-kB activity in airway epithelial differentiation remains controversial. In the present study we demonstrate that Nf-kB adaptor protein Myd88 deficiency promotes increased airway submucosal gland abundance and abnormal epithelial differentiation in proximal adult airways. Abnormal airway differentiation was not developmentally determined, became exacerbated following acute lung injury, and did not involve altered epithelial proliferation or apoptosis. Instead, we demonstrate that tracheal Myd88 deficiency promotes upregulation of a unique gene expression profile that includes activation of alternate, Myd88-independent Nf-kB signalling. Finally, we show that these effects are not intrinsically maintained in vitro using an air-liquid interface epithelial culture. This finding indicates that Myd88 deficiency promotes adult airway remodelling by regulating non-epithelial, non-cell autonomous Nf-kB activity. 20 microarray samples of whole trachea RNA in total: 5 samples wildtype control tissue 5 samples Myd88 KO control tissue 5 samples wildtype 3 day polidocanol injury tissue 5 samples Myd88 KO 3 day polidocanol injury tissue
Project description:Airway remodelling in chronic obstructive pulmonary disease (COPD) originates, in part, from smoking-induced changes in airway basal stem/progenitor cells (BCs). Based on the knowledge that bone morphogenetic protein 4 (BMP4) influences epithelial progenitor function in the developing and adult mouse lung, we hypothesised that BMP4 signalling may regulate the biology of adult human airway BCs relevant to COPD. BMP4 signalling components in human airway epithelium were analysed at the mRNA and protein levels, and the differentiation of BCs was assessed using the BC expansion and air-liquid interface models in the absence/presence of BMP4, BMP receptor inhibitor and/or small interfering RNAs against BMP receptors and downstream signalling.
Project description:Airway remodelling in chronic obstructive pulmonary disease (COPD) originates, in part, from smoking-induced changes in airway basal stem/progenitor cells (BCs). Based on the knowledge that bone morphogenetic protein 4 (BMP4) influences epithelial progenitor function in the developing and adult mouse lung, we hypothesised that BMP4 signalling may regulate the biology of adult human airway BCs relevant to COPD. BMP4 signalling components in human airway epithelium were analysed at the mRNA and protein levels, and the differentiation of BCs was assessed using the BC expansion and air-liquid interface models in the absence/presence of BMP4, BMP receptor inhibitor and/or small interfering RNAs against BMP receptors and downstream signalling.
Project description:The airway epithelium is a key protective barrier whose integrity is preserved by the self-renewal and differentiation of basal progenitor cells. Epithelial cells are central to the pathogenesis of multiple chronic lung diseases for which age is a principle risk factor. Children are also less susceptible to SARS-CoV-2 infection, suffer less severe symptoms than adults and have a lower rate of mortality. Few studies have addressed differences between airway epithelial cells in children and adults. Here, we perform bulk RNA sequencing studies in laser-captured whole epithelium, FACS-sorted basal cells and cultured basal cells, as well as in vitro cell proliferation experiments, to address the intrinsic molecular differences between paediatric and adult airway basal cells. We find that, while the cellular composition of the paediatric and adult tracheal epithelium is broadly similar, in cell culture, paediatric airway epithelial cells displayed higher colony forming ability, better in vitro growth and outcompeted adult cells in competitive proliferation assays. Although recurring differences between airway epithelial gene expression were seen between samples from children and adults, RNA sequencing showed broad conservation of transcriptional programmes. Genes associated with SARS-CoV-2 infection were not differentially expressed between children and adults, although individuals showed some variability in their expression of viral infection-associated genes. Our results chart important cell intrinsic differences in transcriptional profile and regenerative capacity between tracheal epithelial cells of children and adults.
Project description:The airway epithelium is a key protective barrier whose integrity is preserved by the self-renewal and differentiation of basal progenitor cells. Epithelial cells are central to the pathogenesis of multiple chronic lung diseases for which age is a principle risk factor. Children are also less susceptible to SARS-CoV-2 infection, suffer less severe symptoms than adults and have a lower rate of mortality. Few studies have addressed differences between airway epithelial cells in children and adults. Here, we perform bulk RNA sequencing studies in laser-captured whole epithelium, FACS-sorted basal cells and cultured basal cells, as well as in vitro cell proliferation experiments, to address the intrinsic molecular differences between paediatric and adult airway basal cells. We find that, while the cellular composition of the paediatric and adult tracheal epithelium is broadly similar, in cell culture, paediatric airway epithelial cells displayed higher colony forming ability, better in vitro growth and outcompeted adult cells in competitive proliferation assays. Although recurring differences between airway epithelial gene expression were seen between samples from children and adults, RNA sequencing showed broad conservation of transcriptional programmes. Genes associated with SARS-CoV-2 infection were not differentially expressed between children and adults, although individuals showed some variability in their expression of viral infection-associated genes. Our results chart important cell intrinsic differences in transcriptional profile and regenerative capacity between tracheal epithelial cells of children and adults.
Project description:The airway epithelium is a key protective barrier whose integrity is preserved by the self-renewal and differentiation of basal progenitor cells. Epithelial cells are central to the pathogenesis of multiple chronic lung diseases for which age is a principle risk factor. Children are also less susceptible to SARS-CoV-2 infection, suffer less severe symptoms than adults and have a lower rate of mortality. Few studies have addressed differences between airway epithelial cells in children and adults. Here, we perform bulk RNA sequencing studies in laser-captured whole epithelium, FACS-sorted basal cells and cultured basal cells, as well as in vitro cell proliferation experiments, to address the intrinsic molecular differences between paediatric and adult airway basal cells. We find that, while the cellular composition of the paediatric and adult tracheal epithelium is broadly similar, in cell culture, paediatric airway epithelial cells displayed higher colony forming ability, better in vitro growth and outcompeted adult cells in competitive proliferation assays. Although recurring differences between airway epithelial gene expression were seen between samples from children and adults, RNA sequencing showed broad conservation of transcriptional programmes. Genes associated with SARS-CoV-2 infection were not differentially expressed between children and adults, although individuals showed some variability in their expression of viral infection-associated genes. Our results chart important cell intrinsic differences in transcriptional profile and regenerative capacity between tracheal epithelial cells of children and adults.
Project description:Neural stem cells (NSCs) in the developing and postnatal brain have distinct positional identities that dictate the types of neurons they generate. While morphogens initially establish NSC positional identity in the neural tube, it is unclear how such regional differences are maintained as the forebrain grows much larger and anatomically more complex. We found that the maintenance of NSC positional identity requires a Mixed-lineage leukemia 1 (Mll1)-dependent epigenetic memory system. After establishment by sonic hedgehog (SHH), ventral NSC identity became independent of this morphogen. Even transient MLL1 inhibition caused a durable loss of ventral identity, resulting in the generation of neurons with the characteristics of dorsal NSCs in vivo. Thus, spatial information provided by morphogens can be transitioned to epigenetic mechanisms that maintain regionally distinct developmental programs in the forebrain.