Nuclear Yes-Associated Protein Activation in an ex vivo Murine Lung Model of Fetal Tracheal Occlusion.

INTRODUCTION

In this study, we aimed to investigate the expression of nuclear Yes-associated protein (nYAP), a molecule involved in mechanotransduction, during fetal lung development in a novel ex vivo mouse model of congenital diaphragmatic hernia (CDH) lung hypoplasia.

METHODS

Pregnant CD1 mice were gavaged nitrofen at E8.5 to induce CDH lung hypoplasia. At E16.5, fetal lungs were harvested and cultured ex vivo for 72 h with or without tracheal occlusion (hypo-TO and hypo, respectively). Age-matched normal fetal lung controls (norm-TO and norm) were evaluated in parallel. Whole lungs at E16.5 + 3 were analyzed for nYAP and markers of distal epithelial differentiation by immunohistochemistry and quantitative gene expression.

RESULTS

There was robust nYAP expression in norm-TO lungs. Analysis of the distal lung parenchyma in normal and hypoplastic lungs showed enhanced epithelial nYAP expression in the distal airways of both norm-TO and hypo-TO lungs relative to their respective controls. Hypo lungs had the lowest expression of nYAP among the groups. There was significantly increased expression of both Ctgf and Cyr61 in hypo-TO lungs compared to hypo lungs without tracheal occlusion (Ctgf: 1.57 ± 0.43 and 1.02 ± 0.23, p = 0.016; Cyr61: 1.60 ± 0.34 and 1.01 ± 0.17, p = 0.003).

CONCLUSION

In this ex vivo model, tracheal occlusion upregulates nYAP in both control and hypoplastic lungs during the canalicular stage of development, suggesting a critical role of the mechanosensory response molecule in CDH lung hypoplasia.