Project description:Claudin proteins are major constituents of epithelial and endothelial tight junctions (TJ), where they serve as regulators of paracellular permeability to ions and solutes. Claudin-18, a member of the large claudin family, is highly expressed in lung epithelium. To elucidate the role of claudin-18 in alveolar epithelial barrier function and fluid homeostasis, we generated claudin-18 knockout (C18 KO) mice. Increased alveolar fluid clearance (AFC) observed in C18 KO mice may have accounted for absence of lung edema despite increased alveolar solute permeability compared to wild type (WT) controls. Higher AFC in C18 KO mice was associated with higher Na-K-ATPase activity and increased expression of the Na-K-ATPase β1 subunit compared to WT controls. Consistent with in vivo findings, alveolar epithelial cell (AEC) monolayers derived from C18 KO mice exhibited lower transepithelial electrical resistance (RT) accompanied by increased solute and ion permeability without changes in ion selectivity. Expression of claudin-3 and claudin-4 was markedly increased in whole lung and in freshly isolated AEC from C18 KO mice, while claudin-5 was unchanged. In contrast, occludin, another major component of the TJ complex, was significantly decreased in C18 KO lung. Further analysis revealed rearrangements in the F-actin cytoskeleton in C18 KO MAECM. These findings demonstrate a crucial non-redundant role for claudin-18 in regulation of alveolar epithelial tight junction composition and permeability to ions and solutes. Importantly, increased AFC in C18 KO mice identifies additional roles for claudin-18 in alveolar fluid homeostasis beyond its direct contributions to barrier properties of the alveolar epithelium.
Project description:Claudin proteins are major constituents of epithelial and endothelial tight junctions (TJ), where they serve as regulators of paracellular permeability to ions and solutes. Claudin-18, a member of the large claudin family, is highly expressed in lung epithelium. To elucidate the role of claudin-18 in alveolar epithelial barrier function and fluid homeostasis, we generated claudin-18 knockout (C18 KO) mice. Increased alveolar fluid clearance (AFC) observed in C18 KO mice may have accounted for absence of lung edema despite increased alveolar solute permeability compared to wild type (WT) controls. Higher AFC in C18 KO mice was associated with higher Na-K-ATPase activity and increased expression of the Na-K-ATPase β1 subunit compared to WT controls. Consistent with in vivo findings, alveolar epithelial cell (AEC) monolayers derived from C18 KO mice exhibited lower transepithelial electrical resistance (RT) accompanied by increased solute and ion permeability without changes in ion selectivity. Expression of claudin-3 and claudin-4 was markedly increased in whole lung and in freshly isolated AEC from C18 KO mice, while claudin-5 was unchanged. In contrast, occludin, another major component of the TJ complex, was significantly decreased in C18 KO lung. Further analysis revealed rearrangements in the F-actin cytoskeleton in C18 KO MAECM. These findings demonstrate a crucial non-redundant role for claudin-18 in regulation of alveolar epithelial tight junction composition and permeability to ions and solutes. Importantly, increased AFC in C18 KO mice identifies additional roles for claudin-18 in alveolar fluid homeostasis beyond its direct contributions to barrier properties of the alveolar epithelium. Animals with a ubiquitous knockout (C18 KO) were obtained by crossing mice harboring a conditional (floxed) allele of claudin-18 (Cldn18F/F) with CMV-cre deleter mice to delete exons 2 and 3 by Cre/loxP recombination.
Project description:Constitutive knockdown of Cldn18 in mice showed lung enlargement and increased proliferation of alveolar epithelial type II (AT2) cells. Lung AT2 cells were isolated from wild-type and knockout mice and subjected to microarray analysis. Results provide insight into the role of Cldn18 in controlling organ size and stem progenitor cells.
Project description:Purpose: To determine early changes in gene expression that drive gastric cancer development in the landscape of CLDN18 loss using RNAseq. Results: Although claudin-18 is a tight junction protein and should regulate paracellular permeabiity and/or ion flux across the mucosa, we showed this protein is rather a potent tumor suppressor that regulates cellular signaling and differentiation pathways in gastric epithelial cells. Methods: Stomach neck region mRNA profiles of 7-day-old wild-type (WT) and claudin-18 knockout (CLDN18−/−) mice were generated by deep sequencing, in triplicate, using the Illumina HiSeq2000 sequencing system. The resulting sequences were mapped to the Mouse genome (mm10) using STAR aliger and P-values were adjusted using the Benjamini-Hochberg procedure (J R Statist Soc B 1995;57:289-300). Conclusions: Loss of claudin-18 promotes gastric cancer development by modulating the expression program of gastric epithelial cells, including cellular signaling and differentiation pathways that are required for mucosal homeostasis.
Project description:This SuperSeries is composed of the following subset Series: GSE32727: EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors [human] GSE32904: EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors [mouse] Refer to individual Series
Project description:Epithelial-mesenchymal transition (EMT) is an important mechanism in carcinogenesis. To determine the mechanisms that are involved in the regulation of EMT is crucial to develop new biomarkers and therapeutic targets towards cancers. In this study, when TGFß1 and TNFa were used to induce EMT in human lung carcinoma A549 cells, we were surprised to find an increase in an epithelial cell tight junction marker, Claudin 1. We further identified that it was the TNFa and not the TGFß1 that induced the fibroblast-like morphology changes. TNFa also caused the increase in Claudin-1 gene expression and protein levels in Triton X-100 soluble cytoplasm fraction. Down-regulation of Claudin-1, using small interfering RNA (siRNA), inhibited 75% of TNFa-induced gene expression changes. Claudin-1 siRNA effectively blocked TNFa-induced molecular functional networks related to inflammation and cell movement. Wound-healing assay showed that Claudin-1 siRNA was able to significantly reduce TNF-enhanced cell migration. Furthermore, over expression of Claudin 1 with a Claudin 1-pcDNA3.1/V5-His vector enhanced cell migration. In conclusion, these observations indicate that Claudin 1 acts as a critical signal mediator in TNFa-induced gene expression and cell migration in human lung cancer cells. Further analyses of these cellular processes may be helpful in developing novel therapeutic strategies.
Project description:The tight junction (TJ) proteins claudin-2 and -10a form paracellular cation and anion channels, respectively, and have both been reported to be expressed in the proximal tubule (PT). However, the physiological role of claudin-10a in the kidney is yet obscure. Mice deficient in claudin-10a were generated and successful knockout was confirmed by Southern Blot, Western Blot and immunofluorescence staining. The functionality of isolated PTs was investigated electrophysiologically. Compensatory regulation was studied by pharmacological intervention, RNA-Seq analysis, Western Blot and immunofluorescence staining.
Project description:Epithelial-mesenchymal transition (EMT) is an important mechanism in carcinogenesis. To determine the mechanisms that are involved in the regulation of EMT is crucial to develop new biomarkers and therapeutic targets towards cancers. In this study, when TGFÃ1 and TNFa were used to induce EMT in human lung carcinoma A549 cells, we were surprised to find an increase in an epithelial cell tight junction marker, Claudin 1. We further identified that it was the TNFa and not the TGFÃ1 that induced the fibroblast-like morphology changes. TNFa also caused the increase in Claudin-1 gene expression and protein levels in Triton X-100 soluble cytoplasm fraction. Down-regulation of Claudin-1, using small interfering RNA (siRNA), inhibited 75% of TNFa-induced gene expression changes. Claudin-1 siRNA effectively blocked TNFa-induced molecular functional networks related to inflammation and cell movement. Wound-healing assay showed that Claudin-1 siRNA was able to significantly reduce TNF-enhanced cell migration. Furthermore, over expression of Claudin 1 with a Claudin 1-pcDNA3.1/V5-His vector enhanced cell migration. In conclusion, these observations indicate that Claudin 1 acts as a critical signal mediator in TNFa-induced gene expression and cell migration in human lung cancer cells. Further analyses of these cellular processes may be helpful in developing novel therapeutic strategies. 4 groups (with or without TNFα, control or Claudin 1 siRNA) of human lung adenocarcinoma A549 cells with 3 replicates per group.