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: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:The Atlantic salmon (Salmo salar) genome contains 10 chitinase encoding genes, but little is known about the function of these chitinases. Three of the chitinase genes have previously been shown to be expressed in the stomach tissue of Atlantic salmon. In the current study we show that the protein products of these genes, the family 18 glycoside hydrolase (GH18) chitinases, Chia.3, Chia.4 and Chia.7 are secreted into the stomach mucosa and are amongst the most abundant proteins in this matrix.
Project description:Fundic mucosa gene expression in wildtype vs gastrin knockout, gastrin replaced gastrin KO and gastrin-CCK double knockout mice Fundic mucosal scraping RNA were isolated from WT, Gastrin Knockout, Gastrin replaced KO and Gastrin-CCK double knockout mice. Targets from three biological replicates of each were generated and the expression profiles were determined using Affymetrix murine 430A arrays. Comparisons between the sample groups allow the identification of genes with gastrin responsiveness and Gastrin-CCK double effect . Keywords: repeat
Project description:Differential methylation profiling of 18 colon tumor samples vs normal colon mucosa using the LogRatios of samples/reference panel 18 colon tumors and 8 normal mucosa
Project description:The Glucagon-Like Peptide-1 (GLP-1) is a proglucagon-derived peptide with regulatory effects on many tissues, including the pancreas, stomach, liver, brain and heart. The rapid inactivation of intestinally secreted GLP-1 by DPP-4 enzyme raises the question of its production in proximity of its targets. Here we show some epithelial cells producing GLP-1 in the stomach of rats and humans. These cells respond specifically to intragastric load of glucose by increasing GLP-1 levels in the portal vein, in vivo in the rat. GLP-1 is known as an incretin, it decreases blood glucose levels after a meal by increasing insulin secretion in response to glucose. The increased GLP-1 secretion in obese individuals who have undergone bariatric surgery is considered as a keystone in the glycemic improvement observed in those patients. Here we show that obese rats that underwent RYGB or VSG exhibit a new gastric mucosa phenotype with expansion and hyperplasia of the mucus neck cells, and increased density of gastric GLP-1 expressing cells compared to sham animals. These findings highlight a potential role of stomach-derived GLP-1 in the outcomes of bariatric surgeries and raise the question of its role in physiology and metabolism.
Project description:BACKGROUND & AIMS: The immune system comprises an innate and an adaptive immune response to combat pathogenic agents. The human enteropathogen Salmonella enterica serovar Typhimurium invades the intestinal mucosa and triggers an early innate pro-inflammatory host gene response, which results in diarrheal disease. Several host factors are involved in the acute early response to Salmonella infection. Transcription factors and transcription co-regulators have an especially important function, because they are required for the expression and synthesis of pro-inflammatory cytokines, chemokines and adhesion molecules. A central transcription factor involved in inflammation is NF-κB, which requires the nuclear protein PARP1 as co-factor for the expression of some of its target genes. Here, we investigated the role of PARP1 during Salmonella infection using a mouse model for Salmonella-induced colitis. METHODS: To study enterocolitis by Salmonella Typhimurium, an established mouse model system, which relies on streptomycin-pretreatment prior to Salmonella infection, was employed. Histopathologic signs of inflammation and cecum colonization at various time-points after infection of wild type and PARP1 knockout mice were analyzed. PARP1 expression in the gut mucosa was studied by quantitative RT-PCR, Western blot and immunofluorescence. Gene expression profiles of infected and control infected mice in the wild type or PARP1 knockout background were obtained by whole mouse genome arrays and confirmed by quantitative RT-PCR. 2 genotypes (wildtype, PARP1 knockout), 2 treatments (Salmonella SB300 infection, Salmonella SB161 control infection), 2 time-points (6h, 10h). 2-3 replicates/condition.