Claudin-18–mediated YAP activity regulates lung stem and progenitor cell homeostasis and tumorigenesis
Beiyun Zhou, … , Edward D. Crandall, Zea Borok
Beiyun Zhou, … , Edward D. Crandall, Zea Borok
Published February 5, 2018
Citation Information: J Clin Invest. 2018;128(3):970-984. https://doi.org/10.1172/JCI90429.
View: Text | PDF
Research Article Pulmonology Article has an altmetric score of 6

Claudin-18–mediated YAP activity regulates lung stem and progenitor cell homeostasis and tumorigenesis

Abstract

Claudins, the integral tight junction (TJ) proteins that regulate paracellular permeability and cell polarity, are frequently dysregulated in cancer; however, their role in neoplastic progression is unclear. Here, we demonstrated that knockout of Cldn18, a claudin family member highly expressed in lung alveolar epithelium, leads to lung enlargement, parenchymal expansion, increased abundance and proliferation of known distal lung progenitors, the alveolar epithelial type II (AT2) cells, activation of Yes-associated protein (YAP), increased organ size, and tumorigenesis in mice. Inhibition of YAP decreased proliferation and colony-forming efficiency (CFE) of Cldn18–/– AT2 cells and prevented increased lung size, while CLDN18 overexpression decreased YAP nuclear localization, cell proliferation, CFE, and YAP transcriptional activity. CLDN18 and YAP interacted and colocalized at cell-cell contacts, while loss of CLDN18 decreased YAP interaction with Hippo kinases p-LATS1/2. Additionally, Cldn18–/– mice had increased propensity to develop lung adenocarcinomas (LuAd) with age, and human LuAd showed stage-dependent reduction of CLDN18.1. These results establish CLDN18 as a regulator of YAP activity that serves to restrict organ size, progenitor cell proliferation, and tumorigenesis, and suggest a mechanism whereby TJ disruption may promote progenitor proliferation to enhance repair following injury.

Authors

Beiyun Zhou, Per Flodby, Jiao Luo, Dan R. Castillo, Yixin Liu, Fa-Xing Yu, Alicia McConnell, Bino Varghese, Guanglei Li, Nyam-Osor Chimge, Mitsuhiro Sunohara, Michael N. Koss, Wafaa Elatre, Peter Conti, Janice M. Liebler, Chenchen Yang, Crystal N. Marconett, Ite A. Laird-Offringa, Parviz Minoo, Kunliang Guan, Barry R. Stripp, Edward D. Crandall, Zea Borok

×

Figure 2

Increased alveolar epithelial type II (AT2) cell proliferation in Cldn18–/– lungs in vivo and colony-forming efficiency and proliferation in vitro.

Options: View larger image (or click on image) Download as PowerPoint
Increased alveolar epithelial type II (AT2) cell proliferation in Cldn18...
Representative immunofluorescence (IF) images (A) and quantification (B) show EdU+NKX2-1+ (yellow) cells are increased in Cldn18–/– mouse lungs at E18. n = 5 mice of each genotype. Unpaired 2-tailed t test. *P < 0.05. Scale bars: 50 μm. Representative IF images (C) and quantification (D) show EdU+NKX2-1+ cells (arrow) are increased in Cldn18–/– mouse lungs 3 weeks postnatally. n = 5 mice of each genotype. Unpaired 2-tailed t test. *P < 0.05. Scale bars: 50 μm. Representative FACS (E) and quantification (F) show a greater percentage of AT2 cells in S and G2/M phase in Cldn18–/– versus WT mice. PI, propidium iodide. n = 3 mice of each genotype (age ~5 months). Two-way ANOVA with Bonferroni’s correction. *P < 0.05 versus WT. Increased size (G and H) and number (I) of colonies generated from Cldn18–/– AT2 cells. n ≥ 3 biological replicates. Unpaired 2-tailed t test. *P < 0.05. Scale bars: 100 μm. (J) SFTPC (red)/AQP5 (green) double staining shows that both WT and Cldn18–/– AT2 cells in 3D culture give rise to cells expressing the AT1 cell marker AQP5. n = 3. Scale bars: 50 μm. Ki67 (red) and SFTPC (green) double staining (K) and quantification (L) demonstrate increased proliferation of Cldn18–/– AT2 cells in organoid culture. DAPI is the nuclear counterstain. n = 3 biological replicates. Unpaired 2-tailed t test. *P < 0.05. Scale bars: 20 μm. Bar graphs represent the mean ± SEM for B, D, F, H, I, and L.