Hippo signaling pathway regulated branching morphogenesis of fetal lung under hypoxia

Background Hypoxia affects embryonic development, leading to increased neonatal mortality. We investigated the effects of hypoxia on fetal lung branching via Hippo signaling pathway. Materials and methods Fetal lungs were dissected from 11.5 embryonic day ICR pregnant mice. Ex vivo fetal lungs were cultured under control (21% O₂) or hypoxic (1% O₂) conditions for 3 days, while human fetal lung fibroblasts IMR-90 were exposed for 24 hours. We performed RNA sequencing analysis on mouse fetal whole lung after 3 days of exposure. Biochemical analysis including lactate dehydrogenase (LDH) assay and Interleukin 6 (IL-6) were measured in lung supernatants. Expression of YAP, TAZ, SOX2, SOX9, FGF10 and FGFR2 was determined using Western blot. Immunofluorescence was utilized for observing YAP and SOX2 expression on mouse fetal lung slices. Results We observed that under hypoxic conditions, branching morphogenesis of ex vivo mouse fetal lungs were inhibited, with the number of terminal bronchioles and lung area in hypoxia lower after 72 hours (p < 0.05). Besides, LDH and IL-6 were increased in hypoxia group of fetal lungs and IMR-90 cells (p < 0.05). Western blot showed that an increase in phosphorylation of YAP and TAZ under hypoxic exposure. SOX2 expression was decreased in hypoxic fetal lungs and IMR-90 cells (p < 0.05). The expression of YAP and SOX2 in Fibronectin cells of fetal lung decreased after exposure to hypoxia but FGF10 was over-expressed in IMR-90 cells (p < 0.05). Conclusions The regulation of the Hippo signaling pathway in fetal lung fibroblasts is associated with branching morphogenesis under hypoxic conditions. Prenatal hypoxia exposure may contribute to the onset of fetal lung disorders.