Project description:VS94 gene expression at different time-points in SAPI medium in absence and presence of AI-2 was studied. Autoinducer-2 (AI-2) is produced by many species of bacteria, including various commensal bacteria and is involved in inter-species communication. Since, pathogens encounter AI-2 once they enter the human gastro-intestinal tract; we studied the effects of presence of AI-2 on various phenotypes associated with infection and colonization of enterohemorrhagic Escherichia coli (EHEC) namely, chemotaxis, motility and attachment to HeLa cells. AI-2 attracted EHEC when observed in agarose plug assays and also increased EHEC motility by 1.44-fold. AI-2 also increased EHEC attachment to HeLa cells by 1.6-fold; hence, suggesting that exposure to AI-2 inside the gastro-intestinal tract can play an important role in EHEC colonization. We then investigated the global effects of AI-2 on EHEC gene expression using DNA microarrays at various time-points. We found that AI-2 controls virulence gene expression and several other groups of genes (flagellar genes, iron related genes, biofilm genes etc.) associated with virulence in a time-dependent manner. Hence, through these studies we have shown that AI-2 may be a key component in EHEC infection of human gastro-intestinal tract. Keywords: Time course
2008-03-21 | GSE9388 | GEO
Project description:Whole genome assembly of the sea snail (Babylonia areolata)
Project description:Background and aims: Dysregulation of intestinal epithelial cells performance associates with an array of pathologies whose onset mechanisms are incompletely understood. The aim of the present study was to provide a map of gene expresssion patterns along the human healthy adult gastro-intestinal tract and to implement a new procedure for microarray data noise filtering that would allow their use as a reference when screening for pathological deviations, such as inflammatory bowel disease (IBD). Methods: Gene expression profiles in antrum, duodenum, jejunum, ileum and transverse colon biopsies were measured with the Affymetrix U133A array and principal component analysis was used to identify region-selective biomarkers. These data were intersected with highly variable genes from a public dataset of gene expression in the ileal and colonic healthy regions of UC and Crohn’s disease patients. Moreover, gene sets covering gut functions not entirely accounted for by the available public tools were constructed to monitor their expression along the GI tract. Results: 166 genes were found to be responsible for distinguishing the five regions considered. Fourteen had never been described in the GI tract, including a semaphorin probably implicated in pathogen invasion, and six other novel genes. Similar analysis of the IBD datasets revealed that samples stratify based on disease rather than on the intestinal region. This withstanding, eleven genes were identified as possible early predictors of Crohn’s and/or UC in ileum and/or colon. These include CLCA4 and SLC26A2, both implicated in ion transport. Conclusions: This novel approach, validated by retrieving known gene profiles, allowed the identification of promising new leads both in health and IBD state. Keywords: gastro-intestinal tract comparison
Project description:To explore the regulatory mechanism of intestinal flora in Citrobacter rodentium -induced intestinal infection by transcriptome analysis at miRNA molecular level.
Project description:During extreme physiological stress, the intestinal tract can be transformed into a harsh environment characterized by regio- spatial alterations in oxygen, pH, and phosphate concentration. When the human intestine is exposed to extreme medical interventions, the normal flora becomes replaced by pathogenic species whose virulence can be triggered by various physico-chemical cues leading to lethal sepsis. We previously demonstrated that phosphate depletion develops in the mouse intestine following surgical injury and triggers intestinal P. aeruginosa to express a lethal phenotype that can be prevented by oral phosphate ([Pi]) supplementation.
Project description:The endodermal lining of the adult gastro-intestinal tract harbors stem cells that are responsible for the day-to-day regeneration of the epithelium. Stem cells residing in the pyloric glands of the stomach and in the small intestinal crypts differ in their differentiation program and in the gene repertoire that they express. Both types of stem cells have been shown to grow from single cells into 3D structures (organoids) in vitro. We show that single adult Lgr5-positive stem cells, isolated from small intestinal organoids, require Cdx2 to maintain their intestinal identity and are converted cell-autonomously into pyloric stem cells in the absence of this transcription factor. Clonal descendants of Cdx2null small intestinal stem cells enter the gastric differentiation program instead of producing intestinal derivatives. Conversely, forced expression of Cdx2 in gastric organoids results in their intestinalization. The intestinal genetic program is thus critically dependent on the single transcription factor encoding gene Cdx2.