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

Abstract

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.