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 5

CLDN18 regulates AT2 cell proliferation and YAP activity, and CLDN18 and YAP interact.

Options: View larger image (or click on image) Download as PowerPoint
CLDN18 regulates AT2 cell proliferation and YAP activity, and CLDN18 and...
CLDN18 overexpression prevents increases in colony number (A) and size (B). n = 3 independent experiments. Unpaired 2-tailed t test. *P < 0.05. Nuclear YAP (C) and EdU labeling (red) (D) decrease following transduction of Cldn18–/– AT2 cells with CLDN18-expressing lentivirus. GFP fluorescence (green) (D) indicates most cells were transduced with virus. n = 3. Scale bars: 50 μm. (E) CLDN18 overexpression inhibits activation of a YAP luciferase reporter, but not of YAP mutant, YAP5SA, that is resistant to phosphorylation by LATS1/2. YAP– and YAP+ indicate absence versus presence of overexpressed YAP, respectively. n = 3 independent experiments. One-way ANOVA with Bonferroni’s correction. *P <0.05. (F) Endogenous CLDN18 associates with p-YAP and ZO-1 in WT AT2 cell membranes. IgG = negative control. Input is cell lysate. (G) pDsRed-YAP was cotransfected with pCMV-CLDN18-GFP (upper panel) or control vector pCMV-GFP (lower panel) into MLE-15 cells. YAP colocalizes with CLDN18 at sites of cell-cell contact. n = 2. Scale bars: 5 μm. (H) IP with anti–p-LATS1/2 Ab shows decreased p-LATS1/2 and decreased association of p-LATS1/2 with p-YAP in Cldn18–/– (lane 4) compared with WT (lane 3) AT2 cell membranes. IgG = negative control IP with WT and Cldn18–/– lysates (lanes 1 and 2, respectively). n = 3 independent experiments. Input is lung tissue lysate; p-LATS1/2 cannot be detected in input. (I) IP with anti–p-YAP Ab shows decreased p-YAP and decreased association of p-YAP with p-LATS1/2 in Cldn18–/– (lanes 2 and 4) compared with WT (lanes 1 and 3) AT2 cell membranes. IgG = negative control. n = 3 independent experiments. Input is lung tissue lysate; p-LATS1/2 cannot be detected in input. Bar graphs represent the mean ± SEM for A, B, and E. Inputs were run in the same gel (F, H, and I) but were noncontiguous.