The development of the lung is a highly regulated and complex process that is not fully characterised. Lung development starts at embryonic day (E) 9.5 in the mouse and E26 in the human. Although there have been many studies into the lung development many of the mechanisms regulating lung organogenesis are still unclear. In recent years, the importance of epigenetic regulators in embryogenesis has been established but epigenetic control of lung morphogenesis is largely underexplored. We aim to identify epigenetic modifiers that are critical for lung development and to establish their mechanism of action.

We have developed a novel E11.5 epithelial lung cell culture system that allow us to keep primary cells in culture for 14 days, harvesting cells at three time points. Using this platform, we performed a short-hairpin RNA (shRNA) knockdown screen, targeting 200 genes (~10 hairpins/gene) that are known to be involved in enzymatic epigenetic regulation. DNA sequencing at the three time points enabled us to identify an increase or decrease in representation of the hairpins over time. The top genes identified in the screen are currently being validated using in vitro and ex vivo culture systems to determine their role on lung progenitor activity and branching morphogenesis.

To provide further insights into the endogenous expression of epigenetic factors in the developing lung, RNAseq was performed using our novel culture platform at the three harvest time points, as well as on freshly sorted E11.5 lung epithelial cells and stromal cells. Comparing the two datasets allowed us to focus our validation studies on genes that are expressed in the normal developing lung and are not affected by the culture system.

Understanding the regulation of lung development will provide a better understanding of the lung organogenesis and how disruptions in normal biology can cause early lung diseases such as bronchopulmonary dysplasia or can have an impact on lung disorders later in life such as COPD or lung cancer.