Unknown,Transcriptomics,Genomics,Proteomics

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Regulation of antibacterial defense in the small intestine by the nuclear bile acid receptor

ABSTRACT: Decreased bile secretion in rodents by either ligation of the common bile duct or induction of cirrhosis causes changes in the small intestine, including bacterial overgrowth and translocation across the mucosal barrier. Oral administration of bile acids inhibits these effects. The genes regulated by FXR in ileum suggested that it might contribute to the enteroprotective actions of bile acids. To test this hypothesis, mice were administered either GW4064 or vehicle for 2 days and then subjected to bile duct ligation (BDL) or sham operation. After 5 days, during which GW4064 or vehicle treatment was continued, the mice were killed and their intestines were analyzed for FXR target gene expression. Mice were treated with or without FXR ligand GW4064 for 2 days prior to bile duct ligation surgery and for 5 days after surgery. After 5 days the mice were sacrificed and the ileum collected and processed for gene expression analysis. Gene expression in the ilium from each sample group was assayed in duplicate using Affymetrix Mouse Genome 430A 2.0 Gene Chips.

ORGANISM(S): Mus musculus

SUBMITTER: Scott Ochsner

PROVIDER: E-GEOD-40821 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Extrahepatic cholestasis leads to complex injury and repair processes that result in bile infarct formation, neutrophil infiltration, cholangiocyte and hepatocyte proliferation, extracellular matrix remodeling, and fibrosis. To identify early molecular mechanisms of injury and repair after bile duct obstruction, microarray analysis was performed on liver tissue 24 hours after bile duct ligation (BDL) or sham surgery. The most upregulated gene identified encodes plasminogen activator inhibitor 1 (PAI-1, Serpine 1), a protease inhibitor that blocks urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activity. Because PAI-1, uPA, and tPA influence growth factor and cytokine processing as well as extracellular matrix remodeling, we evaluated the role of PAI-1 in cholestatic liver injury by comparing the injury and repair processes in wild-type (WT) and PAI-1-deficient (PAI-1-/-) mice after BDL. PAI-1-/- mice had fewer and smaller bile infarcts, less neutrophil infiltration, and higher levels of cholangiocyte and hepatocyte proliferation than WT animals after BDL. Furthermore, PAI-1-/- mice had higher levels of tPA activation and mature hepatocyte growth factor (HGF) after BDL than WT mice, suggesting that PAI-1 effects on HGF activation critically influence cholestatic liver injury. This was further supported by elevated levels of c-Met and Akt phosphorylation in PAI-1-/- mice after BDL. In conclusion, PAI-1 deficiency reduces liver injury after BDL in mice. These data suggest that inhibiting PAI-1 might attenuate liver injury in cholestatic liver diseases. Total RNA isolated using TRI Reagent (Sigma, St. Louis, MO) was purified with an RNeasy mini kit (Qiagen, Valencia, CA). Twenty micrograms cRNA was hybridized to a mouse GeneChip (U74Av2, Affymetrix, Santa Clara, CA) at the Siteman Cancer Center GeneChip facility as described by the manufacturer. Analyses used one mouse per chip. Gene expression changes were analyzed using Affymetrix MicroArray Suite 4.0 and GeneChip 3.1 Expression Analysis and Statistical Algorithms (Affymetrix). The complete methodology and full data sets for all 6 analyzed chips are available at http://bioinformatics.wustl.edu.beckerproxy.wustl.edu This study compares the injury and repair processed in wild-type mice after BDL.

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Regulation of antibacterial defense in the small intestine by the nuclear bile acid receptor

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