Lef1 Promotes Foxi1-Dependent Ionocyte Specification by Airway Submucosal Gland Progenitors

Airway submucosal gland progenitors (SMGPs) act as a reserve stem cell population for epithelial regeneration in the lungs. However, the mechanisms that control the long-term maintenance of these cells are not fully understood. A new study has identified the Ncf1/Igfbp2 signaling pathway as a key regulator of SMGP fitness and epithelial lineage specification in mice.

To investigate this, researchers genetically disrupted the Ncf1 or Igfbp2 genes in mouse SMGPs and then serially passaged these cells to monitor changes in proliferation, organoid-forming capacity, expression of epithelial markers, DNA damage, DNA repair responses, and telomere length. They also evaluated the differentiated epithelia for Cftr-mediated anion transport, a critical ion transport function, as well as pulmonary ionocyte specification, which is crucial for ion regulation in the lungs.

The results showed that disrupting Ncf1 or Igfbp2 preserved the identity of SMGP cells while enhancing their proliferative ability and organoid-forming capacity. Importantly, these cells accumulated less DNA damage over time, which was attributed to improved DNA repair mechanisms. Furthermore, epithelia derived from Ncf1-/- and Igfbp2-/- SMGPs maintained higher Cftr-mediated anion transport and exhibited enhanced pulmonary ionocyte specification, both in vitro and in vivo.

These beneficial effects were observed independently of telomere shortening, suggesting that the observed improvements were due to alterations in stress responses and DNA damage handling rather than replicative limits.

The study concludes that Ncf1/Igfbp2 signaling plays a crucial role in maintaining the fitness and proper maturation of airway epithelial cells. These findings could have significant implications for developing regenerative therapies for lung diseases such as cystic fibrosis, where impaired airway epithelial function is a major challenge.