he lung is a complex tissue composed of the airway epithelium, mesenchyme, blood vessels and cells of the immune system. Understanding the cellular differentiation mechanisms in the developing lung may help us to understand the pathogenesis of devastating lung diseases like asthma COPD and lung cancer. We have purified GFP-labeled mouse bronchial cells at different perinatal and postnatal stages by FACS. We use the CC10 CreER strain (Rawlins et al, 2009), which labels secretory cells, ciliated cells and a progenitor population that gives rise to these two mature cell types. We will use single cell sequencing to profile the fully mature cells and their progenitor(s) during airway maturation. RNA sequencing 100 GFP-positive cells at 4 developmental time points and analysis of the results by hierarchical clustering will identify the lineage relationships and describe the transcriptome of the cell types. In the long term we will expand this analysis to include non-epithelial lung cells, which constitute a much more complex and challenging cell population. We expect that the gene expression analysis of bronchial epithelial cells will reveal cell differentiation mechanisms in the lung and will help us to understand the roles of secretory and ciliated cells in lung development and function.