Hippo signaling pathway regulates branching morphogenesis of the fetal lung under hypoxia

Hypoxia is known to disrupt embryonic organogenesis and increase the risk of neonatal respiratory disorders. The Hippo pathway is crucial in regulating organ development, size, and cell proliferation. However, the mechanism of how hypoxia affects lung development through this pathway remains unclear.

Fetal lungs were dissected from embryonic day 11.5 ICR mice and cultured ex vivo under normoxic (21% O₂) or hypoxic (1% O₂) conditions for 72 h, while human fetal lung fibroblasts (IMR-90) were exposed for 24 h. RNA sequencing analysis was performed on mouse fetal lungs. Biochemical analyses of lactate dehydrogenase and interleukin-6 were performed on supernatants. Expression levels of Hippo pathway-related proteins were determined by Western blot and immunofluorescence.

Hypoxia markedly inhibited branching morphogenesis, reducing terminal bronchioles and total lung area (p < 0.05). Elevated LDH and IL-6 levels indicated cytotoxicity and inflammation. Western blot analysis revealed increased phosphorylation of YAP/TAZ, accompanied by decreased SOX2 expression (p < 0.05). Furthermore, genes related to cell differentiation and adhesion were also downregulated, indicating disrupted epithelial-mesenchymal coordination.

These findings suggest that hypoxia may alter Hippo signaling in fetal lung fibroblasts, thereby impairing branching morphogenesis. Prenatal hypoxia exposure might contribute to abnormal lung development and increase susceptibility to neonatal pulmonary disorders.

Prenatal hypoxia impairs fetal lung branching morphogenesis by modulating Hippo signaling and fibroblast-derived factors. Prenatal hypoxia enhances cytotoxicity and inflammatory cytokine production in fetal lungs and fibroblasts. This study provides new insights into the pathogenesis of hypoxia-related neonatal lung disorders and suggests Hippo signaling as a potential therapeutic target.