ScRNA-seq for lung BASCs stem cells at the bronchioalveolar-duct junction
Ontology highlight
ABSTRACT: Characterizing the stem cells responsible for lung repair and regeneration is important for the treatment of pulmonary diseases. Recently, a unique cell population located at the bronchioalveolar-duct junctions has been proposed to comprise endogenous stem cells for lung regeneration. However, the role of bronchioalveolar stem cells (BASCs) in vivo remains debated, and the contribution of such cells to lung regeneration is not known. Here we generated a genetic lineage-tracing system that uses dual recombinases (Cre and Dre) to specifically track BASCs in vivo. Fate-mapping and clonal analysis showed that BASCs became activated and responded distinctly to different lung injuries, and differentiated into multiple cell lineages including club cells, ciliated cells, and alveolar type 1 and type 2 cells for lung regeneration. This study provides in vivo genetic evidence that BASCs are bona fide lung epithelial stem cells with deployment of multipotency and self-renewal during lung repair and regeneration.
Project description:Bronchioalveolar stem cells (BASCs) are a potential source for lung regeneration, but direct in vivo evidence is critically missing since specific genetic labeling of BASCs has not been possible. We developed a novel cell tracing approach based on intein-mediated assembly of newly engineered split-effectors, allowing selective targeting of dual-marker expressing BASCs. We found that BASCs generate the majority of distal lung airway cells after bronchioalveolar damage but only moderately contribute to cellular turnover under homeostatic conditions. Importantly, DTA-mediated ablation of BASCs compromised proper regeneration of distal airways. The study defines BASCs as crucial components of the lung repair machinery and provides a paradigmatic example for the detection and manipulation of stem cells that cannot be recognized by a single marker alone.
Project description:Epithelial organs including the lung are known to possess regenerative abilities through activation of endogenous stem cell populations but the molecular pathways regulating stem cell expansion and regeneration are not well understood. Here we show that Gata6 regulates the temporal appearance and number of bronchioalveolar stem cells (BASCs) in the lung leading to the precocious appearance of BASCs and concurrent loss in epithelial differentiation in Gata6 null lung epithelium. This expansion of BASCs is the result of a dramatic increase in canonical Wnt signaling in lung epithelium upon loss of Gata6. Expression of the non-canonical Wnt receptor Fzd2 is down-regulated in Gata6 mutants and increased Fzd2 or decreased β-catenin expression rescues, in part, the lung epithelial defects in Gata6 mutants. During lung epithelial regeneration, we show that canonical Wnt signaling is activated in the niche containing BASCs and forced activation of Wnt signaling leads to a dramatic increase in BASC numbers. Moreover, Gata6 is required for proper lung epithelial regeneration and postnatal loss of Gata6 leads to increased BASC expansion and decreased differentiation. Together, these data demonstrate that Gata6 regulated Wnt signaling controls the balance between stem/progenitor expansion and epithelial differentiation required for both lung development and regeneration. Experiment Overall Design: 3 replicates of each condition-wild-type and GATA6 null tissue. 6 total samples.
Project description:Alveolar type 2 (AT2) cells are stem cells of the alveolar epithelia. Previous genetic lineage tracing studies reported multiple cellular origins for AT2 cells after injury. However, conventional lineage tracing based on Cre-loxP has the limitation of non-specific labeling. Thus, the exact contribution of various epithelial cells to the pools of AT2 cells under different conditions remains unclear. Here, we used dual recombinases-mediated intersectional genetic lineage tracing to investigate the cellular origins of AT2 cells during lung homeostasis, injury and repair. In contrast to previous studies, we found AT1 cells were terminally differentiated cells and did not contribute to AT2 cells after lung injury and repair. Distinctive, but simultaneous, labeling of club cells, bronchioalveolar stem cells (BASCs), and AT2 cells revealed the exact contribution of each to AT2 cells after lung injury. Moreover, we found that club cells have the potential to rebuild virtually all alveoli in some severely injured lung regions. Mechanistically, Notch signaling promotes a BASCs-to-AT2 cell transition, but it inhibits club cell-to-AT2 cell conversion during lung repair. This intersectional genetic lineage tracing strategy with enhanced precision allowed us to elucidate the physiological role of AT1, club, BASCs, and AT2 cells to alveolar regeneration after injury.
Project description:Epithelial organs including the lung are known to possess regenerative abilities through activation of endogenous stem cell populations but the molecular pathways regulating stem cell expansion and regeneration are not well understood. Here we show that Gata6 regulates the temporal appearance and number of bronchioalveolar stem cells (BASCs) in the lung leading to the precocious appearance of BASCs and concurrent loss in epithelial differentiation in Gata6 null lung epithelium. This expansion of BASCs is the result of a dramatic increase in canonical Wnt signaling in lung epithelium upon loss of Gata6. Expression of the non-canonical Wnt receptor Fzd2 is down-regulated in Gata6 mutants and increased Fzd2 or decreased β-catenin expression rescues, in part, the lung epithelial defects in Gata6 mutants. During lung epithelial regeneration, we show that canonical Wnt signaling is activated in the niche containing BASCs and forced activation of Wnt signaling leads to a dramatic increase in BASC numbers. Moreover, Gata6 is required for proper lung epithelial regeneration and postnatal loss of Gata6 leads to increased BASC expansion and decreased differentiation. Together, these data demonstrate that Gata6 regulated Wnt signaling controls the balance between stem/progenitor expansion and epithelial differentiation required for both lung development and regeneration. Keywords: gene targets in knockout mouse model
Project description:The purpose of this research is to study the cellular origins of EGFR-mutant lung cancers and their responses to therapies. We discovered that activation of EGFR T790M/L858R mutation in lung epithelial cells can drive lung cancers with alveolar or bronchiolar features, which can be originated from alveolar type 2 (AT2) cells or bronchioalveolar stem cells (BASCs), but not basal cells or club cells of the trachea. Crucially, the tumoroids with different cell-of-origins or epigenetic states had distinct drug vulnerabilities.
Project description:Mps One Binder Kinase Activator (MOB)1A/1B are core components of the Hippo pathway. These proteins, which coactivate LArge Tumor Suppressor homolog (LATS) kinases, are also tumor suppressors. To investigate MOB1A/B’s roles in normal physiology and lung cancer, we generated doxycycline (Dox)-inducible, bronchioalveolar epithelium–specific, null mutations of MOB1A/B in mice [SPC-rtTA/(tetO)7-Cre/Mob1aflox/flox/Mob1b-/-; termed luMob1DKO) mice]. Most mutants (70%) receiving Dox in utero [luMob1DKO (E6.5-18.5) mice] died of hypoxia within 1hr post-birth. Their alveolar epithelial cells showed increased proliferation, impaired YAP1/TAZ-dependent differentiation, and decreased surfactant protein production, all features characteristic of human respiratory distress syndrome (RDS). Intriguingly, mutant mice that received Dox postnatally [luMob1DKO (P21–41) mice] did not develop spontaneous lung adenocarcinomas, and urethane treatment-induced lung tumor formation was decreased (rather than increased). Lungs of luMob1DKO (P21–41) mice exhibited increased detachment of bronchiolar epithelial cells and decreased numbers of the bronchioalveolar stem cells (BASCs) thought to initiate lung adenocarcinomas. YAP1/TAZ-NKX2.1-dependent expression of collagen XVII, a key hemidesmosome component, was also reduced. Thus, a MOB1-YAP1/TAZ-NKX2.1 axis is essential for normal lung homeostasis and expression of the collagen XVII protein necessary for alveolar stem cell maintenance in the lung niche.
Project description:Murine bronchioalveolar stem cells play a key role in pulmonary epithelial maintenance and repair but their molecular profile is poorly described so far. In this study, we used antibodies directed against Sca-1 and CD34, two markers originally ascribed to pulmonary cells harboring regenerative potential, to isolate single putative stem cells from murine lung tissue. The mean detection rate of positive cells was 8 per 106 lung cells. We then isolated and globally amplified the mRNA of positive cells to analyze gene expression in single cells. The resulting amplicons were then used for molecular profiling by transcript specific polymerase chain reaction (PCR) and global gene expression analysis using microarrays. Single marker-positive cells displayed a striking heterogeneity for the expression of epithelial and mesenchymal transcripts on the single cell level. Nevertheless, they could be subdivided into two cell populations: Sca-1+/CD34- and Sca-1+/CD34+ cells. In these subpopulations, transcripts of the epithelial marker Epcam (CD326) were exclusively detected in Sca-1+/CD34- cells (p = 0.03), whereas mRNA of the mesenchymal marker PdgfrM-NM-1 (CD140a) was detected in both subpopulations and more frequently in Sca-1+/CD34+ cells (p = 0.04). FACS analysis confirmed the existence of a PdgfrM-NM-1 positive subpopulation within Epcam+/Sca-1+/CD34- epithelial cells. Gene expression analysis by microarray hybridization identified transcripts differentially expressed between the two cell types as well as between epithelial reference cells and Sca-1+/CD34+ single cells, and selected transcripts were validated by quantitative PCR. Our results suggest a more mesenchymal commitment of Sca-1+/CD34+ cells and a more epithelial commitment of Sca-1+/CD34- cells. In summary, the study shows that single cell analysis enables the identification of novel molecular markers in yet poorly characterized populations of rare cells. Our results could further improve our understanding of Sca-1+/CD34+,- cells in the biology of the murine lung. Single cells of 10 Sca-1+/CD34+/CD31-/CD45-, 7 Sca-1+/CD34-/CD31-/CD45-, and 12 Sca-1-/CD34-/CD31-/CD45- were analyzed. Although the raw data are two channel only Cy5 signal of each file as analyzed. The Cy5 channel for each gene is normalized to the average Cy5 intensity of the gene across all samples.
Project description:Murine bronchioalveolar stem cells play a key role in pulmonary epithelial maintenance and repair but their molecular profile is poorly described so far. In this study, we used antibodies directed against Sca-1 and CD34, two markers originally ascribed to pulmonary cells harboring regenerative potential, to isolate single putative stem cells from murine lung tissue. The mean detection rate of positive cells was 8 per 106 lung cells. We then isolated and globally amplified the mRNA of positive cells to analyze gene expression in single cells. The resulting amplicons were then used for molecular profiling by transcript specific polymerase chain reaction (PCR) and global gene expression analysis using microarrays. Single marker-positive cells displayed a striking heterogeneity for the expression of epithelial and mesenchymal transcripts on the single cell level. Nevertheless, they could be subdivided into two cell populations: Sca-1+/CD34- and Sca-1+/CD34+ cells. In these subpopulations, transcripts of the epithelial marker Epcam (CD326) were exclusively detected in Sca-1+/CD34- cells (p = 0.03), whereas mRNA of the mesenchymal marker Pdgfrα (CD140a) was detected in both subpopulations and more frequently in Sca-1+/CD34+ cells (p = 0.04). FACS analysis confirmed the existence of a Pdgfrα positive subpopulation within Epcam+/Sca-1+/CD34- epithelial cells. Gene expression analysis by microarray hybridization identified transcripts differentially expressed between the two cell types as well as between epithelial reference cells and Sca-1+/CD34+ single cells, and selected transcripts were validated by quantitative PCR. Our results suggest a more mesenchymal commitment of Sca-1+/CD34+ cells and a more epithelial commitment of Sca-1+/CD34- cells. In summary, the study shows that single cell analysis enables the identification of novel molecular markers in yet poorly characterized populations of rare cells. Our results could further improve our understanding of Sca-1+/CD34+,- cells in the biology of the murine lung.