Background: The selective absorption of nutrients and other food constituents in the small intestine is mediated by a group of transport proteins and metabolic enzymes, often collectively called intestinal barrier proteins. An important receptor that mediates the effects of dietary lipids on gene expression is the peroxisome proliferator-activated receptor alpha (PPAR), which is abundantly expressed in enterocytes. In this study we examined the effects of acute nutritional activation of PPAR on expression of genes encoding intestinal barrier proteins. To this end we used triacylglycerols composed of identical fatty acids in combination with gene expression profiling in wild-type and PPAR-null mice. Treatment with the synthetic PPAR agonist WY14643 served as reference.
PPARalpha-mediated effects of dietary lipids on intestinal barrier gene expression.
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View SamplesWe studied the effect of dietary fat type, varying in polyunsaturated/saturated fatty acid ratio's (P/S) on development of metabolic syndrome. C57Bl/6J mice were fed purified high-fat diets (45E% fat) containing palm oil (HF-PO; P/S 0.4), olive oil (HF-OO; P/S 1.1) or safflower oil (HF-SO; P/S 7.8) for 8 weeks. A low-fat palm oil diet (LF-PO; 10E% fat) was used as a reference. Additionally, we analyzed diet-induced changes in gut microbiota composition and mucosal gene expression. The HF-PO diet induced a higher body weight gain and liver triglyceride content compared to the HF-OO, HF-SO or LF-PO diet. In the intestine, the HF-PO diet reduced microbial diversity and increased the Firmicutes/Bacteroidetes ratio. Although this fits a typical obesity profile, our data clearly indicate that an overflow of the HF-PO diet to the distal intestine, rather than obesity itself, is the main trigger for these gut microbiota changes. A HF-PO diet-induced elevation of lipid metabolism-related genes in the distal small intestine confirmed the overflow of palm oil to the distal intestine. Some of these lipid metabolism-related genes were previously already associated with the metabolic syndrome. In conclusion, our data indicate that saturated fat (HF-PO) has a more stimulatory effect on weight gain and hepatic lipid accumulation than unsaturated fat (HF-OO and HF-SO). The overflow of fat to the distal intestine on the HF-PO diet induced changes in gut microbiota composition and mucosal gene expression. We speculate that both are directly or indirectly contributive to the saturated fat-induced development of obesity and hepatic steatosis.
Saturated fat stimulates obesity and hepatic steatosis and affects gut microbiota composition by an enhanced overflow of dietary fat to the distal intestine.
Sex, Specimen part
View SamplesObesity and insulin resistance are two major risk factors underlying the metabolic syndrome. To gain more insight in the role of the small intestine in the etiology of these metabolic disorders, a microarray study was performed on small intestines (SI) of C57BL/6J mice that were fed a high fat diet mimicking the fatty acid composition of a Western-style human diet. The mice became obese and developed dietary fat-induced glucose intolerance. For gene expression profiling, the small intestines were subdivided in three equal parts along the longitudinal axis. The most pronounced effects of dietary fat were detected in part 2 of the small intestine. The biological processes that were most extensively modulated on a high fat diet were related to lipid metabolism, especially - and -fatty acid oxidation seemed to play an important role, cell cycle and inflammation/immune response. An additional secretome analysis revealed differentially expressed secreted proteins, such as Il18, Ffgf15, Mif, Igfbp3 and Angptl4, which might provoke systemic effects in peripheral organs by influencing their metabolic homeostasis. Furthermore, many of the dietary fat-modulated genes and biological processes in small intestine were previously already associated with obesity and/or insulin resistance. Together, the data of this exploratory study provided various leads for an essential role of the small intestine in development of obesity and/or insulin resistance.
The role of the small intestine in the development of dietary fat-induced obesity and insulin resistance in C57BL/6J mice.
Sex, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Glutamine supplementation suppresses herpes simplex virus reactivation.
Specimen part
View SamplesChronic viral infections are difficult to treat and new approaches, particularly those involving enhancing immune responses are needed. Herpes simplex virus (HSV) establishes latency, reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and activated T cells require increased metabolism of glutamine for their proliferation. We found that treatment of HSV-1 latently infected mice and HSV-2 infected guinea pigs with supplemental oral glutamine reduced virus reactivation. Transcriptome analysis of mice treated with glutamine showed that several interferon (IFN)- inducible genes were upregulated. Unlike wild-type mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in IFN- knock-out mice. Mice treated with glutamine had higher numbers of HSV-specific IFN- producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN--associated immune response and reduce the rate of reactivation of latent virus infection.
Glutamine supplementation suppresses herpes simplex virus reactivation.
Specimen part
View SamplesChronic viral infections are difficult to treat and new approaches, particularly those involving enhancing immune responses are needed. Herpes simplex virus (HSV) establishes latency, reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and activated T cells require increased metabolism of glutamine for their proliferation. We found that treatment of HSV-1 latently infected mice and HSV-2 infected guinea pigs with supplemental oral glutamine reduced virus reactivation. Transcriptome analysis of mice treated with glutamine showed that several interferon (IFN)- inducible genes were upregulated. Unlike wild-type mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in IFN- knock-out mice. Mice treated with glutamine had higher numbers of HSV-specific IFN- producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN--associated immune response and reduce the rate of reactivation of latent virus infection.
Glutamine supplementation suppresses herpes simplex virus reactivation.
Specimen part
View SamplesWe have investigated the role of actin dynamics and the effect of actin cytoskeleton modifying agents on retinoid receptor-mediated transactivation. Using Nef, an actin modifying HIV-1 protein, the role of LMK1/CFL1-mediated actin dynamics in receptor function was studied. The effect of Nef expression on transcriptome was investigated following transfection of HEK293 cells with Nef-expressing plasmid. The array data identified Nef-induced inhibition of a number of genes that contain retinoid receptor binding sites in their promoters.
LIM kinase 1 - dependent cofilin 1 pathway and actin dynamics mediate nuclear retinoid receptor function in T lymphocytes.
Cell line
View SamplesDengue fever is an important tropical illness for which there is currently no virus-specific treatment. To shed light on mechanisms involved in the cellular response to dengue virus (DV), we assessed gene expression changes, using Affymetrix GeneChips (HG-U133A), of infected primary human cells and identified changes common to all cells. The common response genes included a set of 23 genes significantly induced upon DV infection of human umbilical vein endothelial cells (HUVECs), dendritic cells (DCs), monocytes, and B cells (analysis of variance, P < 0.05). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), one of the common response genes, was identified as a key link between type I and type II interferon response genes. We found that DV induces TRAIL expression in immune cells and HUVECs at the mRNA and protein levels. The induction of TRAIL expression by DV was found to be dependent on an intact type I interferon signaling pathway. A significant increase in DV RNA accumulation was observed in anti-TRAIL antibody-treated monocytes, B cells, and HUVECs, and, conversely, a decrease in DV RNA was seen in recombinant TRAIL-treated monocytes. Furthermore, recombinant TRAIL inhibited DV titers in DV-infected DCs by an apoptosis-independent mechanism. These data suggest that TRAIL plays an important role in the antiviral response to DV infection and is a candidate for antiviral interventions against DV.
TRAIL is a novel antiviral protein against dengue virus.
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View SamplesWe analyzed gene expression in 184 (finite life span) and HMT3522 S1 (immortal non-malignant) HMECs on successive days (3, 5, and 7) post-seeding in a laminin-rich extracellular matrix assay. Both HMECs underwent growth arrest in G0/G1 and differentiated into polarized acini between days 5 and 7.
Gene expression signature in organized and growth-arrested mammary acini predicts good outcome in breast cancer.
Sex, Specimen part, Cell line, Time
View SamplesNonmalignant human mammary epithelial cells (HMEC) seeded in laminin-rich extracellular matrix (lrECM) form polarized acini and, in doing so, transit from a disorganized proliferating state to an organized growth-arrested state. We hypothesized that the gene expression pattern of organized and growth-arrested HMECs would share similarities with breast tumors with good prognoses. Using Affymetrix HG-U133A microarrays, we analyzed the expression of 22,283 gene transcripts in 184 (finite life span) and HMT3522 S1 (immortal nonmalignant) HMECs on successive days after seeding in a lrECM assay. Both HMECs underwent growth arrest in G0-G1 and differentiated into polarized acini between days 5 and 7. We identified gene expression changes with the same temporal pattern in both lines and examined the expression of these genes in a previously published panel of microarray data for 295 breast cancer samples. We show that genes that are significantly lower in the organized, growth-arrested HMEC than in their proliferating counterparts can be used to classify breast cancer patients into poor and good prognosis groups with high accuracy. This study represents a novel unsupervised approach to identifying breast cancer markers that may be of use clinically.
Gene expression signature in organized and growth-arrested mammary acini predicts good outcome in breast cancer.
Sex, Specimen part, Cell line
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