Yes-associated protein is dysregulated during nitrofen-induced hypoplastic lung development due to congenital diaphragmatic hernia.

Abstract

Congenital diaphragmatic hernia (CDH) is a birth defect associated with abnormal lung development. Yes-associated protein (YAP) is a core kinase of the Hippo pathway, which controls organ size during development. The absence of YAP protein during lung development results in hypoplastic lungs comparable to the lung phenotype in CDH (Mahoney, Dev Cell 30(2):137-150, 2014). We aimed to describe the expression of YAP during normal and nitrofen-induced abnormal lung development. Intra-gastric administration of dams with 100mg of nitrofen was used to induce CDH and abnormal lung development in the embryos. Immunofluorescence was performed to visualize the localization of YAP and p-YAP during lung development (E15, E18, E21). Western Blotting was used to determine the abundance of YAP and p-YAP in E21 control and nitrofen-induced hypoplastic CDH lungs. Immunofluorescence demonstrated cytoplasmic localization of YAP protein in airway epithelial and mesenchymal cells of nitrofen-induced hypoplastic lungs compared to nuclear localization in control lungs. Western Blotting showed a decrease (p = 0.0188) in abundance of YAP (active form) and increase in p-YAP (inactive form) in hypoplastic lungs compared to control lungs. Our results demonstrate that YAP protein is mostly phosphorylated, inactive, and expressed in the cytoplasm at the later stages of nitrofen-induced hypoplastic lung development indicating that the alteration in regulation of YAP can be associated with the pathogenesis of abnormal lung development in experimental CDH.