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 9

Conditional deletion of Becn1 reduces NKX2-1 expression.

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Conditional deletion of Becn1 reduces NKX2-1 expression. (A) IHC and con...
(A) IHC and confocal IF microscopic images show NKX2-1 and glycogen content (PAS staining) in lung tissue sections from E18.5 Becn1Epi-KO and littermate control (WT) fetuses. In the littermate control, the type II cuboidal alveolar cells stained positive for NKX2-1 (top left inset, red arrowheads), whereas type I squamous alveolar cells lacked NKX2-1 expression (top left inset, black arrows). In the Becn1Epi-KO lung, only NKX2-1+ cuboidal cells were visible (bottom left inset, red arrowheads). In the IF staining (middle panel), NKX2-1+ cells are shown in red, whereas nuclei were stained with DAPI (blue). Scale bars: 50 μm. Graph shows densitometric analysis of NKX2-1 IF results. Data represent the mean ± SEM (n = 4 separate lungs). *P < 0.05 versus control, by Student’s t test. (B) Representative immunoblot for NKX2-1. Graphs shows densitometric analysis of NKX2-1 expression in whole-lung lysate harvested from Becn1Epi-KO and littermate control embryos at E18.5. ACTB was used as a protein loading control. Data represent the mean ± SEM (n = 4 separate lungs). *P < 0.05 versus WT control, by Student’s t test.