Autophagy is required for lung development and morphogenesis
Behzad Yeganeh, … , Cameron Ackerley, Martin Post
Behzad Yeganeh, … , Cameron Ackerley, Martin Post
Published June 4, 2019
Citation Information: J Clin Invest. 2019;129(7):2904-2919. https://doi.org/10.1172/JCI127307.
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Research Article Development Pulmonology

Autophagy is required for lung development and morphogenesis

Abstract

Bronchopulmonary dysplasia (BPD) remains a major respiratory illness in extremely premature infants. The biological mechanisms leading to BPD are not fully understood, although an arrest in lung development has been implicated. The current study aimed to investigate the occurrence of autophagy in the developing mouse lung and its regulatory role in airway branching and terminal sacculi formation. We found 2 windows of epithelial autophagy activation in the developing mouse lung, both resulting from AMPK activation. Inhibition of AMPK-mediated autophagy led to reduced lung branching in vitro. Conditional deletion of beclin 1 (Becn1) in mouse lung epithelial cells (Becn1Epi-KO), either at early (E10.5) or late (E16.5) gestation, resulted in lethal respiratory distress at birth or shortly after. E10.5 Becn1Epi-KO lungs displayed reduced airway branching and sacculi formation accompanied by impaired vascularization, excessive epithelial cell death, reduced mesenchymal thinning of the interstitial walls, and delayed epithelial maturation. E16.5 Becn1Epi-KO lungs had reduced terminal air sac formation and vascularization and delayed distal epithelial differentiation, a pathology similar to that seen in infants with BPD. Taken together, our findings demonstrate that intrinsic autophagy is an important regulator of lung development and morphogenesis and may contribute to the BPD phenotype when impaired.

Authors

Behzad Yeganeh, Joyce Lee, Leonardo Ermini, Irene Lok, Cameron Ackerley, Martin Post

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Figure 11

Pulmonary phenotype following deletion of epithelial Becn1 at canalicular/saccular stages.

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Pulmonary phenotype following deletion of epithelial Becn1 at canalicula...
(A) Representative H&E-stained images of lungs from littermate control (WT) and E16.5 Becn1Epi-KO mice at E17.5, E18.5, and immediately after birth (P0). Scale bars: 100 μm; original magnification, ×20 (insets). (B) Graph shows the radial saccular count and the ATR for littermate control and E16.5 Becn1Epi-KO mice at E18.5. Data represent the mean ± SEM (n = 5 separate lungs). *P < 0.05 versus WT control, by Student’s t test. (C) Confocal IF microscopic images of embryonic lungs (E18.5) stained for the endothelial cell marker CD31 (red). Nuclei were stained with DAPI (blue). Scale bars: 50 μm. (D) Quantification of the CD31/DAPI fluorescence ratio in E18.5 lung tissue from control (WT) and E16.5 Becn1Epi-KO embryos. Results are shown as the mean ± SEM (n = 3 separate lungs). *P < 0.05 versus WT control, by Student’s t test. (E and F) Representative confocal IF microscopic images of E18.5 lung tissue sections from E16.5 Becn1Epi-KO and littermate control mice stained for mature SFTPC (E, red) and SFTPB (F, green). Nuclei were stained with DAPI. The white arrows in the insets point to cuboidal alveolar type II epithelial cells. Scale bars: 25 μm; original magnification, x40 (insets).