Project description:Lung adenocarcinoma (LUAD) is one of the deadliest malignancies worldwide. Dynamic lineage changes within the lung epithelium and the high plasticity of these epithelial cells confound the correct identification of the cell-of-origin of LUAD. Here, we combined lineage-tracing mouse models with an autochthonous cell type-independent LUAD model in order to discover the cellular origin of ALK-translocated LUAD. We identified Club and AT2 cells as the cells-of-origin of LUAD. Moreover, we uncovered epigenetic imprints in the tumours originating from Club or AT2 cells by whole-genome bisulfite sequencing. Single-cell transcriptomes of Club cells at different stages of tumour development identified two trajectories of Club cell evolution. On both routes, tumours lose their Club cell identity and gain an AT2-like phenotype. Together, this study highlights the role of Club cells in LUAD initiation and unveils key mechanisms conferring LUAD heterogeneity.
Project description:Lung adenocarcinoma (LUAD) is one of the deadliest malignancies worldwide. Dynamic lineage changes within the lung epithelium and the high plasticity of these epithelial cells confound the correct identification of the cell-of-origin of LUAD. Here, we combined lineage-tracing mouse models with an autochthonous cell type-independent LUAD model in order to discover the cellular origin of ALK-translocated LUAD. We identified Club and AT2 cells as the cells-of-origin of LUAD. Moreover, we uncovered epigenetic imprints in the tumours originating from Club or AT2 cells by whole-genome bisulfite sequencing. Single-cell transcriptomes of Club cells at different stages of tumour development identified two trajectories of Club cell evolution. On both routes, tumours lose their Club cell identity and gain an AT2-like phenotype. Together, this study highlights the role of Club cells in LUAD initiation and unveils key mechanisms conferring LUAD heterogeneity.
Project description:Regeneration of lung epithelium is vital for maintaining airway function and integrity. An imbalance between epithelial damage and repair is at the basis of numerous chronic lung diseases such as asthma, COPD, pulmonary fibrosis and lung cancer. IGF (Insulin-like Growth Factors) signaling has been associated with most of these respiratory pathologies, although their mechanisms of action in this tissue remain poorly understood. Expression profiles analyses of IGF system genes performed in mouse lung support their functional implication in pulmonary ontogeny. Immuno-localization revealed high expression levels of Igf1r (Insulin-like Growth Factor 1 Receptor) in lung epithelial cells, alveolar macrophages and smooth muscle. To further understand the role of Igf1r in pulmonary homeostasis, two distinct lung epithelial-specific Igf1r mutant mice were generated and studied. The lack of Igf1r disturbed airway epithelial differentiation in adult mice revealed enhanced proliferation and altered morphology in distal airway club cells. During recovery after naphthalene-induced club cell injury, the kinetics of terminal bronchiolar epithelium regeneration was hindered in Igf1r mutants, revealing increased proliferation and delayed differentiation of club and ciliated cells. Amid airway restoration, lungs of Igf1r deficient mice showed increased levels of Igf1, Insr, Igfbp3 and epithelial precursor markers, reduced amounts of Scgb1a1 protein, and alterations in IGF signaling mediators. These results support the role of Igf1r in controlling the kinetics of cell proliferation and differentiation during pulmonary airway epithelial regeneration after injury.
Project description:Gene expression patterns of bronchiolar progenitors and club cells in mouse lung were examined by microarray experiments. Although it has not yet been fully characterized, a subset of epithelial cells lining bronchioles are best understood as bronchiolar progenitors that self-renew over the long term and that can differentiate into more differentiated club cells and ciliated cells. The bronchiolar progenitors are distinct from club cells and characteristically express the alveolar type 2 cell marker, prosurfactant protein C, with lower levels of club cell secretory protein/Scgb1a1. There are also functional differences between them; while club cells can be depleted by naphthalene because of the abundance of cytochrome P450 enzyme Cyp2f2, bronchiolar progenitors are resistant to naphthalene-induced depletion because of defects in the enzyme.
Project description:The club cell, a small airway epithelial (SAE) secretory cell that uniquely expresses SCGB1A1, plays a central role in host defense in the human lung. Based on data demonstrating that ~50% of club cells express MUC5B, a secretory mucin critical for mucociliary clearance, we hypothesized that subpopulations of club cells with distinct functions may exist. To evaluate this, the SAE of normal nonsmokers and healthy cigarette smokers was sampled by bronchoscopy and brushing followed by single cell sequencing using Drop-seq technology. Subpopulations of SCGCB1A1+KRT5loMUC5AC- club cells were assessed by unsupervised clustering to evaluate club cell subpopulations. Immunostaining of SAE in lung sections, brushed SAE cells, and in vitro air-liquid interface culture was utilized to confirm the transcriptomic-based observations. Unsupervised clustering of SCGCB1A1+KRT5loMUC5AC‾ club cells in the SAE identified 3 unique club cell populations that differed by differentiation state and function, including: (1) progenitor; (2) proliferating; and (3) effector subpopulations. The progenitor club cell population was energetically active with high expression of mitochondrial and ribosomal proteins and the highest KRT5 levels vs other club cell populations. The proliferating population, defined by high expression of cyclins and proliferation markers, was the smallest, representing 2% of club cells. The effector club cell cluster expressed transcripts for host defense genes, xenobiotic metabo-lism, and barrier functions commonly associated with club cell function. Comparison of the club cell subpopulations in smokers vs nonsmokers demonstrated that the proportion of the club cell effector population was significantly decreased in smokers with a concomitant significant in-crease in the proliferating cell population. These observations provide novel insights into both the makeup of human SAE club cell subpopulations and smoking-induced changes in club cell biology.
Project description:Rationale: The role of club cells in the pathology of Idiopathic Pulmonary Fibrosis IPF is not well understood. PDIA3, an endoplasmic reticulum (ER) based redox chaperone catalyzes the cysteine disulfide bonds (-S-S-) in various fibrosis-related proteins; however, mechanisms of action of PDIA3 in pulmonary fibrosis is not fully elucidated. Objectives: To examine the role of club cells and PDIA3 in the pathogenesis of pulmonary fibrosis (PF) and therapeutic potential of inhibition of PDIA3 in PF. Methods: The impact of PDIA3 and aberrant club cells in PF was studied by retrospective analysis of human transcriptome data from LGRC, and specific deletion and inhibition of PDIA3 in club cells and blocking Osteopontin (SPP1) downstream of PDIA3 in mice. Measurements and Main Results: The PDIA3 along with club cell secretory protein (SCGB1A1 or CCSP) signatures are upregulated in IPF compared to control patients, and PDIA3 increases correlate with a decrease in lung function in IPF patients. The Bleomycin (BLM) model of PF showed increases in aberrant CCSP and PDIA3 positive cells in the lung parenchyma. Ablation of Pdia3, specifically in CCSP cells, decreases CCSP cells along with PF in mice. The therapeutic administration of a PDI inhibitor LOC14 reversed the BLM-induced CCSP cells and PF in mice. The proteomic screen of the PDIA3 partners revealed SPP1 as a major interactor in PF. Blocking SPP1 attenuated the development of PF in mice. Conclusions: Collectively, this study demonstrates a new relationship of club cells, with PDIA3, SPP1, and a putative pathological function of club cells in pulmonary fibrosis.