Yap/Taz regulate alveolar regeneration and resolution of lung inflammation
Ryan LaCanna, … , Marla R. Wolfson, Ying Tian
Ryan LaCanna, … , Marla R. Wolfson, Ying Tian
Published April 15, 2019
Citation Information: J Clin Invest. 2019;129(5):2107-2122. https://doi.org/10.1172/JCI125014.
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Research Article Pulmonology

Yap/Taz regulate alveolar regeneration and resolution of lung inflammation

Abstract

Alveolar epithelium plays a pivotal role in protecting the lungs from inhaled infectious agents. Therefore, the regenerative capacity of the alveolar epithelium is critical for recovery from these insults in order to rebuild the epithelial barrier and restore pulmonary functions. Here, we show that sublethal infection of mice with Streptococcus pneumoniae, the most common pathogen of community-acquired pneumonia, led to exclusive damage in lung alveoli, followed by alveolar epithelial regeneration and resolution of lung inflammation. We show that surfactant protein C–expressing (SPC-expressing) alveolar epithelial type II cells (AECIIs) underwent proliferation and differentiation after infection, which contributed to the newly formed alveolar epithelium. This increase in AECII activities was correlated with increased nuclear expression of Yap and Taz, the mediators of the Hippo pathway. Mice that lacked Yap/Taz in AECIIs exhibited prolonged inflammatory responses in the lung and were delayed in alveolar epithelial regeneration during bacterial pneumonia. This impaired alveolar epithelial regeneration was paralleled by a failure to upregulate IκBa, the molecule that terminates NF-κB–mediated inflammatory responses. These results demonstrate that signals governing resolution of lung inflammation were altered in Yap/Taz mutant mice, which prevented the development of a proper regenerative niche, delaying repair and regeneration of alveolar epithelium during bacterial pneumonia.

Authors

Ryan LaCanna, Daniela Liccardo, Peggy Zhang, Lauren Tragesser, Yan Wang, Tongtong Cao, Harold A. Chapman, Edward E. Morrisey, Hao Shen, Walter J. Koch, Beata Kosmider, Marla R. Wolfson, Ying Tian

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Figure 6

Regulation of Yap/Taz on IκBa expression and NF-κB transcriptional activity in AECIIs.

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Regulation of Yap/Taz on IκBa expression and NF-κB transcriptional activ...
(A) Schematic of IκBa genomic locus showing potential Tead binding sites (TBM) in the 10 kb upstream of the IκBa transcription start site. (B) Chromatin from MLE-15 cells was immunoprecipitated with either Tead or Yap antibody, and qRT-PCR results were graphed (n = 3). (C) MLE-15 cells were transfected with pGL3 vector containing a IκBa-TBM1-3 or a IκBa-TBM1-3 mutation, in which TBM1 was mutated, along with the expression plasmid encoding either murine Tead2 or Yap or Taz. Twenty-four hours after transfection, cells were processed for luciferase activity measurement (n = 3–6 per group). (D) Adult WT mouse AECIIs were purified, cultured, and infected with either Yap shRNA lentivirus or scramble shRNA lentivirus or were given no treatment. Forty-eight hours after lentiviral infection, cells were processed for NF-κB transcription activity measurement. (E) AECIIs were purified from mouse lungs at 0 dpi and 7 dpi, and their NF-κB transcriptional activity was graphed. (F) MLE-15 cells were infected with either Yap shRNA lentivirus or scramble shRNA lentivirus or were given no treatment. Forty-eight hours after lentiviral infection, cells were transfected with NF-κB luciferase vector containing NF-κB response elements, along with an expression plasmid encoding either murine Yap or Taz. Twenty-four hours after transfection, cells were processed for luciferase activity measurement (n = 3). (G) Schematic model of interaction of Yap/Taz and IκBa/NF-κB in AECIIs. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001, 1-way ANOVA (B, C, D, F) and 2-way ANOVA (E).