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Hepatic gene expression profile of mice exposed to social stress

ABSTRACT: Social stress is well known to be involved in the occurrence and exacerbation of mental illness, and also various life-style related diseases such as hyperinsulinemia, hyperglycemia, cardiovascular diseases and cancer. However, there is little information on tissue-specific gene expression in response to social stress, which reflects our daily life. Liver is one of the most important organs, owing to its biological functions such as energy metabolic homeostasis, metabolization and detoxification of endo- and exogenous substances. In order to elucidate the mechanism underlying response to social stress in the liver, we investigated hepatic gene expression in mice exposed to isolation stress using DNA microarray. Male BALB/c mice (4 weeks old) were housed 5 per cage for 10 days acclimatization. Then mice were exposed to isolation stress for 30 days. After stress treatment, the mouse liver RNA was subjected to DNA microarray analysis. Taking the false discovery rate into account, isolation stress altered expression of 420 genes. Moreover, Gene Ontology analysis of these differentially expressed genes indicated that isolation stress remarkably down-regulated lipid metabolism-related pathway through peroxisome proliferator-activated receptor-alpha (PPARalpha), while lipid biosynthesis pathway regulated by sterol regulatory element binding factor-1 (SREBF-1), Golgi vesicle transport and secretory pathway-related genes were significantly up-regulated. These results suggested that isolation for 30 days, mild and consecutive social stress, not only regulate the systems for lipid metabolism but also cause the endoplasmic reticulum stress in mouse liver.

ORGANISM(S): Mus musculus

PROVIDER: GSE12693 | GEO | 2009/04/09

SECONDARY ACCESSION(S): PRJNA112703

REPOSITORIES: GEO

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Project description:Social stress is well known to be involved in the occurrence and exacerbation of mental illness, and also various life-style related diseases such as hyperinsulinemia, hyperglycemia, cardiovascular diseases and cancer. However, there is little information on tissue-specific gene expression in response to social stress, which reflects our daily life. Liver is one of the most important organs, owing to its biological functions such as energy metabolic homeostasis, metabolization and detoxification of endo- and exogenous substances. In order to elucidate the mechanism underlying response to social stress in the liver, we investigated hepatic gene expression in mice exposed to isolation stress using DNA microarray. Male BALB/c mice (4 weeks old) were housed 5 per cage for 10 days acclimatization. Then mice were exposed to isolation stress for 30 days. After stress treatment, the mouse liver RNA was subjected to DNA microarray analysis. Taking the false discovery rate into account, isolation stress altered expression of 420 genes. Moreover, Gene Ontology analysis of these differentially expressed genes indicated that isolation stress remarkably down-regulated lipid metabolism-related pathway through peroxisome proliferator-activated receptor-ï¡ (PPARï¡), while lipid biosynthesis pathway regulated by sterol regulatory element binding factor-1 (SREBF-1), Golgi vesicle transport and secretory pathway-related genes were significantly up-regulated. These results suggested that isolation for 30 days, mild and consecutive social stress, not only regulate the systems for lipid metabolism but also cause the endoplasmic reticulum stress in mouse liver. Experiment Overall Design: Male BALB/c mice (4 weeks old, Japan SLC, Shizuoka, Japan) weighing 14-18 g were housed 5 per cage. After acclimatization for 10 days, the mice were exposed to isolation (1 mouse per cage). All cages were placed in a foam plastic box in order to avoid social contact. To enhance the feeling of isolation, the bed volume in each cage for the isolated mice was reduced to one-tenth of that in the control group. The weight of bedding chips was about 2 g. All mice were housed in an air-conditioned room ( room temperature: 23 Â± 1Â°C, humidity: 55 Â± 5 %) under 12 h dark/12 h light cycles, with free access to tap water and MF diet (Oriental Yeast Co., Tokyo, Japan).

Project description:Clinical studies have revealed that social support improves the outcome of cancer patients while epidemiological studies suggest that social isolation increases the risk of death associated with several chronic diseases. However, the precise biological consequences of an unfavorable social environment have not been defined. To do so, robust, reproducible pre-clinical models are needed to study the mechanisms whereby an adverse environment impacts on gene expression and cancer biology. Because random assignment of inbred laboratory mice to well-defined social environments allows accurate and repeated measurements of behavioral and endocrine parameters, transgenic mice provide a pre-clinical framework with which to begin to determine gene-environment mechanisms. In this study, we found that female C3(1)/SV40 T-antigen mice deprived of social interaction from weaning exhibited increased expression of genes encoding key metabolic pathway enzymes in the pre-malignant mammary gland. Chronic social isolation was associated with upregulated fatty acid synthesis and glycolytic pathway gene expression - both pathways known to contribute to increased breast cancer growth. Consistent with the expression of metabolic genes, isolated mice subsequently developed significantly larger mammary gland tumors compared to group-housed mice. Endocrine evaluation confirmed that isolated mice developed a heightened corticosterone stress response compared to group-housed mice. Together, these transdisciplinary studies show for the first time that an adverse social environment is associated with altered mammary gland gene expression and tumor growth. Moreover, the identification of specific alterations in metabolic pathways favoring tumor growth suggests potential molecular biomarkers and/or targets (e.g. fatty acid synthesis) for preventive intervention in breast cancer. Experiment Overall Design: SV40 Tag mice we isolated or grouped at weaning. Mouse mammary glands were rapidly excised at necropsy and immediatley flash frozen to detect difference in gene expression between thoraci MG from isolated versus group-housed female mice.

Project description:Since xenobiotics enter the organism via the liver, hepatocytes must cope with numerous perturbations. In particular, exposure to hepatotoxic agents resulting in liver injury triggers a strong alteration in gene expression. The contribution of these transcriptional regulatory networks to the propagation of injury (i.e. by modulation of metabolic pathways, inflammation, proliferation) are not fully understood. Therefore, we conducted a time-resolved gene array study on mouse liver after exposure to a single intraperitoneal injection of the hepatotoxic compound carbon tetrachloride (CCl4). This model induces a transient injury which reaches its maximum between 2 to 3 days after injection, followed by a precise regenerative response. The experiment included early time points (i.e. 2 and 8h) and late time points (1 to 16 days) to cover the initial events induced by CCl4 metabolization and cell stress, and the regenerative phase between 2-6 days after intoxicaiton. C57BL/6N male mice (8-12 weeks old) were obtained from Charles Rivers (Sulzfeld, Germany). The local Ethics committee approved the experiments. 4-5 mice were used for each time point. Mice received a single intraperitoneal injection of CCl4 (1.6 g/kg body weight) dissolved in 0.5 ml olive oil. The liver tissue was collected after 2h, 8h, and 1, 2, 4, 6, 8 and 16 days following CCl4 administration. As control, mice received 0.5 ml of olive oil intraperitonealy for 1 or 8 days. Healthy liver was collected from untreated mice. At the indicated time points, mice were anesthetized and blood was collected from the heart with a 25 gauge needle, using EDTA as anticoagulant, for analysis of the liver transaminases GOT and GPT in serum. Afterwards, the liver was resected, washed in ice cold PBS and sectioned for further analysis. Liver tissue sections of about 0.5 cm2 were snap frozen in liquid nitrogen and stored at -80ﾰC for subsequent isolation of proteins or RNA. RNA was isolated from mouse liver tissue using the Phenol/Chloroform method (Trizolﾮ, Qiagen, Hilden, Germany) according to the manufacturerﾒs instructions. RNA concentration and integrity were determined spectrophotometrically in a Nanodropﾮ2000 (ThermoScientific, Waltham MA, USA) and in a Bioanalyzerﾮ (Agilent, Waldbronn, Germany), respectively.

Project description:Background: Genetic elimination of c-Met signaling in the liver has been shown to impact many cellular pathways involved in repair, regeneration, lipid homeostasis and redox balance. In this study, we analyzed a nutritional model of hepatic steatosis in Met fl/fl ; Alb-Cre +/- (MetKO) mice in a 129SV/C57BL/6 background fed a high cholesterol diet for 30 days. Methods: Liver injury was determined by histopathology and plasma enzymes, transcriptomic changes were examined using gene expression microarrays, and evaluation of key molecules involved in liver damage and lipid homestasis were evaluated by Western blot analysis. Results: We observed that in comparison with wild type mice subjected to the same diet, MetKO mice developed a strong liver lipid deposition, inflammatory infiltration and increment in total bile acids synthesis and liver damage markers. Global transcriptomic changes analysis confirmed the steatosis and cholestasis induced by the high cholesterol diet. In addition, we found affected pathways related to amino acids, glutathione and lipid metabolism, oxidative stress and mitochondria dysfunction. Oxidative stress exacerbation was corroborated by lipid and protein oxidation in liver tissue. To address further, Western blot studies revealed downregulation on Erk, NF-kB and Nrf2 survival pathways and target genes (cyclin D1, SOD1, gamma-GCS), an increment in proapoptotic proteins (p53, caspase 3) and changes in nuclear receptors such as RAR and RXR, which were increased, and CAR, FXR and PPAR alfa, which were decreased, in the MetKO diet. These results are in agreement with the steatosis and cholestasis phenotype. Conclusion: Our data provide evidence of c-Met signaling involvement in lipid metabolism, and bile acids synthesis and excretion. Disruption of these pathways leads to liver dysfunction, improper metabolism and hepatocellular damage. Global transcriptome changes between WT mice vs. c-Met KO mice fed a 2% cholesterol and 0.5% sodium cholate diet (high cholesterol) or a Chow regular diet (Chow) as control. Mice were fed a high cholesterol or chow regular diet for 30 days. Liver tissue was obtained, and RNA was extracted and subjected to Illumina microarray analysis.

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Hepatic gene expression profile of mice exposed to social stress

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