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: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:WT mice and claudin 4 KO mice were exposed to ventilator-induced lung injury (VILI) for 2 hours. We found that in some Cldn4 KO mice, injury was similar to WT, while in others, injury was higher, as assessed by amount of protein leak into broncho-alveolar lavage fluid. We performed RNAseq to find which genes were responsible for higher injury in Cldn4 KO mice.
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:WT mice and claudin 4 KO mice were exposed to ventilator-induced lung injury (VILI) for 2 hours. We found that in some Cldn4 KO mice, injury was similar to WT, while in others, injury was higher, as assessed by amount of protein leak into broncho-alveolar lavage fluid. We performed RNAseq to find which genes were responsible for higher injury in Cldn4 KO mice. WT mice and claudin 4 KO mice were exposed to ventilator-induced lung injury (VILI) for 2 hours. RNA were extracted from whole lungs and RNA sequencing was performed. The samples are (all in duplicates): WT no VILI, Cldn4 KO no VILI, WT VILI, Cldn4 KO VILI with similar injury to WT (Cldn4 KOlow), and Cldn4 KO VILI with higher injury than WT (Cldn4 KOhigh)
Project description:The mucosal epithelium plays a key role in regulating immune homeostasis. Dysregulation of epithelial barrier function is associated with mucosal inflammation. Expression of claudin-2, a pore-forming tight junction protein, is highly upregulated during inflammatory bowel disease (IBD) and, due to its association with epithelial permeability, has been postulated to promote inflammation. Furthermore, claudin-2 also regulates colonic epithelial cell proliferation and intestinal nutrient absorption. However, the precise role of claudin-2 in regulating colonic epithelial and immune homeostasis remains unclear. Here, we demonstrate, using Villin-Claudin-2 transgenic (Cl-2TG) mice, that increased colonic claudin-2 expression unexpectedly protects mice against experimentally induced colitis and colitis-associated cancer. Notably, Cl-2TG mice exhibited increased colon length and permeability as compared with wild type (WT) littermates. However, despite their leaky colon, Cl-2TG mice subjected to experimental colitis were immune compromised, with reduced induction of TLR-2, TLR-4, Myd-88 expression and NF-kB and STAT3 activation. Most importantly, colonic macrophages in Cl-2TG mice exhibited an anergic phenotype. Claudin-2 overexpression also increased colonocyte proliferation and provided protection against colitis-induced colonocyte death. Taken together, our findings have revealed a critical role of claudin-2 in regulating colonic homeostasis, suggesting novel therapeutic strategies for inflammatory conditions of the gastrointestinal tract. 8-10 weeks old male Villin-Claudin-2 transgenic mice and WT littermates were provided either normal drinking water (control) or Dextran Sodium Sulfate (DSS: 4% w/v) for 10 days. 3 replicates each.
Project description:To investigate the claudin-7 function in vivo, we generated a claudin-7 knockout mouse model by gene targeting through homologous recombination. In this study, we report that Cln7-/- pups show Na+, Cl-, and K+ wasting and chronic dehydration phenotypes. The dramatic increase of aldosterone synthase mRNA level suggests that these mice suffer from mishandling of NaCl and fluid in the distal nephrons. Deletion of claudin-7 invokes several compensatory changes, such as increased renin, serum-glucocorticoid-induced kinase 1 (SGK1), epithelial Na+ channel (ENaCα), Na+-Cl- cotransporter (NCC), as well as aquaporin (AQP) 2 mRNA levels, demonstrating the cross talks between paracellular and transcellular ion transport pathways.
Project description:The mucosal epithelium plays a key role in regulating immune homeostasis. Dysregulation of epithelial barrier function is associated with mucosal inflammation. Expression of claudin-2, a pore-forming tight junction protein, is highly upregulated during inflammatory bowel disease (IBD) and, due to its association with epithelial permeability, has been postulated to promote inflammation. Furthermore, claudin-2 also regulates colonic epithelial cell proliferation and intestinal nutrient absorption. However, the precise role of claudin-2 in regulating colonic epithelial and immune homeostasis remains unclear. Here, we demonstrate, using Villin-Claudin-2 transgenic (Cl-2TG) mice, that increased colonic claudin-2 expression unexpectedly protects mice against experimentally induced colitis and colitis-associated cancer. Notably, Cl-2TG mice exhibited increased colon length and permeability as compared with wild type (WT) littermates. However, despite their leaky colon, Cl-2TG mice subjected to experimental colitis were immune compromised, with reduced induction of TLR-2, TLR-4, Myd-88 expression and NF-kB and STAT3 activation. Most importantly, colonic macrophages in Cl-2TG mice exhibited an anergic phenotype. Claudin-2 overexpression also increased colonocyte proliferation and provided protection against colitis-induced colonocyte death. Taken together, our findings have revealed a critical role of claudin-2 in regulating colonic homeostasis, suggesting novel therapeutic strategies for inflammatory conditions of the gastrointestinal tract.
Project description:Proper lung function relies on precisely balanced numbers of specialized epithelial cell types that work together and are maintained in homeostasis. In this study we have described essential roles for the transcriptional regulators YAP and TAZ, which are key effectors of Hippo pathway signaling, in maintaining lung epithelial homeostasis. Phenotypes associated with Yap/Taz deletion include alveolar defects and a striking development of goblet cell metaplasia throughout the airways. Lineage specific deletion of Yap and Taz in Scgb1a1+ cells leads to increased Mucin production within the knockout cells in vivo. In order better characterize the in vivo transcriptional changes associated with Yap/Taz knockout in these cells, we have isolated Scgb1a1 lineage traced cells from control and yap/taz cNull mice and performed bulk RNA sequencing.