#3 The role of Quaking in lung development
Dustin Ameis, University of Manitoba; Richard Keijzer, University of Manitoba
Every day 150 babies are born with congenital diaphragmatic hernia (CDH). These babies develop a hole in their diaphragm through which the abdominal organs herniate and impair lung development. The microRNA miR-200b is abnormally regulated in the lungs of these babies, likely influencing dysfunctional epithelial-mesenchymal transition (EMT) and pulmonary hypertension. Quaking (QKI) is a highly conserved RNA-binding protein targeted by miR-200b, and appears to be regulated during EMT. Here, the previously uncharacterized role of QKI in lung development will be addressed.
We used immunofluorescence staining of the QKI isoforms QKI-5, QKI-6, and QKI-7 in rat lungs during embryonic (E) days 13, 15, 18, and 21, and visualized with confocal microscopy.
QKI-5 localizes to the nucleus and levels are higher in lung mesenchyme and pulmonary veins compared to airway epithelium. QKI-6 is largely excluded from the airway epithelium, but strongly expressed in the cytoplasm and likely appears in sites of early angiogenesis at E13 and E15. QKI-7 is expressed in the nuclei of the airway epithelium and mesenchyme, tightly co-localizing with QKI-5.
Preliminary results suggest that QKI has a role in lung development. The lack of overlap in expression between QKI-6 and the other isoforms implies different functions. Co-localization of QKI-5 and QKI-7 indicates that these isoforms could be co-operating towards a common function. Future experiments, including planned isoform-specific inhibition of QKI on lung explants, could further characterize QKI’s role in lung development. Mechanistic studies linking QKI, miR-200b, and EMT in the developing lung may demonstrate that QKI mediates, in part, the impaired lung development in CDH babies.