Chromosomal instability in early cancer stages is caused by stress on DNA replication. The molecular basis for replication perturbation in this context is currently unknown. We studied the replication dynamics in cells in which a regulator of S-phase entry and cell proliferation, the Rb-E2F pathway, is aberrantly activated. Aberrant activation of this pathway by HPV-16 E6/E7 or cyclin E oncogenes, significantly decreased the cellular nucleotide levels in the newly transformed cells. Exogenously supplied nucleosides rescued the replication stress and DNA damage, and dramatically decreased oncogene-induced transformation. Increased transcription of nucleotide biosynthesis genes, mediated by expressing the transcription factor c-Myc, increased the nucleotide pool and also rescued the replication-induced DNA damage. Our results suggest a model for early oncogenesis in which uncoordinated activation of factors regulating cell proliferation leads to insufficient nucleotides that fail to support normal replication and genome stability.
Nucleotide deficiency promotes genomic instability in early stages of cancer development.
Sex, Specimen part
View SamplesMost commonly used models of non-alcoholic steatohepatitis (NASH) are diets based on specific gene knockouts or represent extreme manipulations of diet. We have examined the effects of modest increased caloric intake and high dietary unsaturated fat content on the development of NASH in male rats using a model in which overfeeding is accomplished via intragastric infusion of liquid diets as a part of total enteral nutrition. Male Sprague dawley rats were fed diets 5% corn oil containing diets at 187 Kcal/kg3/4/d or fed 70% corn oil containing diets at 220 Kcal/kg3/4/d for a period of 3 weeks. Hepatic gene expression were assessed at the end of the study. Our results indicate that overfeeding of high unsaturated fat diets leads to pathological, endocrine and metabolic changes characteristic of NASH patients and is associated with increased oxidative stress and TNF-a.
A new model for nonalcoholic steatohepatitis in the rat utilizing total enteral nutrition to overfeed a high-polyunsaturated fat diet.
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View SamplesThere are concerns regarding possible reproductive toxicity from consumption of soy including an increased risk of endometriosis and endometrial cancer. We used global uterine gene expression profiles in adult ovariectomized (OVX) female rats assessed by RNAseq to examine the estrogenicity of soy protein isolate (SPI) and the potential for feeding SPI to alter estrogen signaling in the uterus. Rats were fed AIN93G diets made with casein (CAS) or SPI from postnatal day (PND) 30. Rats were OVX on PND 50 and infused with 17 beta-estradiol (E2) or vehicle. E2 increased uterine wet weight (P<0.05) and significantly altered expression of 2084 uterine genes. In contrast, SPI feeding had no effect on uterine weight and only altered expression of 177 genes. Overlap between E2 and SPI genes was limited to 69 genes (3%). GO analysis indicated significant differences in uterine biological processes affected by E2 and SPI and little evidence for recruitment of ER alpha to the promoters of ER-responsive genes after SPI feeding. The major E2 up-regulated uterine pathways were cancer pathways and extracellular organization. SPI feeding up-regulated uterine PPAR signaling and fatty acid metabolism. The combination of E2 and SPI feeding resulted in significant regulation of 715 fewer genes relative to E2 alone. In a separate experiment, the combination of E2 and SPI reversed the ability of E2 to induce uterine proliferation in response to the carcinogen dimethybenz(a)anthracene (DMBA). These data suggest SPI does not act as a weak estrogen in the uterus but appears to be a selective estrogen receptor modulator (SERM) interacting with a small sub-set of E2-regulated genes and to be anti-estrogenic in the presence of endogenous estrogens. Overall design: Rat uterus mRNA of ovariectomized adult female rats subject to four different diets (Caseine, Caseine + E2, Soy and Soy+E2 ) were sequenced, in triplicate, in an Illumina GAIIx sequencer.
RNA-sequencing data analysis of uterus in ovariectomized rats fed with soy protein isolate, 17β-estradiol and casein.
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View SamplesAppropriate nutrition during early development is essential for optimal bone mass accretion; however, linkage between early nutrition, childhood bone mass and prevention of bone loss later in life has not been extensively studied. In this report, we have demonstrated several fundamental issues in the field. 1) A significant prevention of ovariectomy (OVX) -induced bone loss from adult rats can occur with only 14 days consumption of a blueberry-containing diet immediately prior to puberty. 2) The molecular mechanisms underlying these effects involve increased myosin production and preserved a shuttle for transcription factors such as Runx2 from cytoplasm to nucleolus which stimulates osteoblast differentiation and reduces mesenchymal stromal cell senescence. 3) The effects of blueberry diet on preserving fidelity of osteoblast differentiation also overcome reduced osteoblast differentiation and activity due to OVX-induced degradation of collagen matrix.
Feeding blueberry diets in early life prevent senescence of osteoblasts and bone loss in ovariectomized adult female rats.
Sex, Specimen part
View SamplesSoy foods have been suggested to have both positive health benefits and potentially adverse effects largely as a result of their content of isoflavone phytoestrogens. Since soy protein isolate (SPI) contains isoflavones, in addition to purported health benefits, safety concerns have been raised regarding the use of SPI and soy formulas, because of potential estrogenic actions during the neonatal period, including the potential for reproductive toxicity, infertility, and the possibility of increased risk for development and recurrence of estrogen sensitive cancers such as breast cancer. In the current study, we used a rat model to compare the effects of SPI with those of 17b-estradiol (E2), on global gene expression profiles and morphology in the female rat mammary gland. Rats were either fed AIN-93G diets containing casein (CAS) or SPI beginning on postnatal day (PND) 30.
Mammary gland morphology and gene expression differ in female rats treated with 17β-estradiol or fed soy protein isolate.
Sex
View SamplesThe majority of babies in the US are formula-fed instead of breast fed. There are major differences in the composition of formulas and breast milk and yet little is known about metabolic differences in babies as the result of feeding these very different diets and how that might affect development or disease risk in later life. One concern is that soy-based formulas might have adverse health effects in babies as a result of the presence of low levels of estrogenic phytochemicals genistein and daidzein which are normally present in soy beans. In the current study, we used a piglet model to look at this question. Piglets were either fed breast milk from the sow or were fed two different infant formulas (cows milk-based or soy-based) from age 2 days to 21 days when pigs are normally weaned onto solid food. Blood glucose and lipids were measured. Formula-fed pigs were found to have lower cholesterol than breast fed piglets and in addition had larger stores of iron in their liver.Microarray analysis was carried out to see if changes in liver gene expression could explain these effects of formula feeding. It was found that overall gene expression profiles were influenced by formula feeding compared to breast fed neonates. Gender-independent and unique effects of formula influenced cholesterol and iron metabolism. Further, soy formula feeding in comparison to milk-based formula failed to reveal any estrogenic actions on hepatic gene expression in either male or female pigs.
Formula feeding alters hepatic gene expression signature, iron and cholesterol homeostasis in the neonatal pig.
Sex
View SamplesThe current study was designed to determine if dietary fatty acid concentration and composition affects the development and progression of nonalcoholic fatty liver disease. Male SD rats were overfed diets low (5%) or high (70%) fat diets via total enteral nutrition where the fat source was olive oil (monounsaturated), or corn oil (polyunsaturated). Overfeeding 5% corn oil produced little steatosis relative to feeding 5% olive oil. This was associated with lower fatty acid synthesis and reduced SREBP-c signaling in the 5% corn oil group. Overfeeding 70% fat diets increased steatosis and lead to increased liver necrosis in the 70% corn oil but not olive oil group. Increased injury after feeding polyunsaturated fat diets was linked to peroxidizability of hepatic free fatty acids and triglycerides and appearance of peroxidaized lipid products HETES and HODES previously linked to clinical nonalcoholic steatohepatitis.
Dietary fat source alters hepatic gene expression profile and determines the type of liver pathology in rats overfed via total enteral nutrition.
Sex
View SamplesIn order to properly understand whether xenoestrogens act as estrogens, it is essential to possess a solid portrait of the physiological effects of exogenous estradiol. Because the estrogen-dependent gene expression is one of the primary biomarkers of estrogenic action, we have assessed effects of three doses of exogenous estradiol (0.1, 1.0 and 10 g/kg of body weight/day) on the mammary gland morphology and gene expression profiles by microarray analysis of prepubertal male and female rats of both sexes compared to untreated controls. Estradiol was administered subcutaneously with minipumps from weaning at PND21 to the end of the experiment at PND33. The data suggest that the male mammary is a sensitive tissue for estrogenicity assessment.
Mammary gland morphology and gene expression signature of weanling male and female rats following exposure to exogenous estradiol.
Sex
View SamplesOxidative stress in adipose tissue and liver has been linked to the development of obesity. NADPH oxidases (NOX) enzymes are a major source of reactive oxygen species (ROS). The current study was designed to determine if NOX2-generated ROS play a role in development of obesity and metabolic syndrome after high fat feeding. Wild type (WT) mice and mice lacking the cytosolic NOX2 activated protein p47phox (P47KO) were fed AIN-93G diets or high fat diets (HFD) containing 45% fat and 0.5% cholesterol for 13 weeks from weaning. Affymetrix array analysis revealed dramatically less expression of mRNA of genes linked to energy metabolism, adipocyte differentiation (PPAR, Runx2) and fatty acid uptake (CD36, lipoprotein lipase) in fat pads from female HFD-P47KO mice compared to HFD-WT females. These data suggest that NOX2 is an important regulator of metabolic homeostasis and that NOX2-associated ROS plays an important role in development of diet-induced obesity particularly in the female
Female mice lacking p47phox have altered adipose tissue gene expression and are protected against high fat-induced obesity.
Sex, Specimen part, Treatment
View SamplesGATA transcription factors are highly conserved among eukaryotes and play roles in transcription of genes implicated in cancer progression and hematopoiesis. However, although their consensus binding sites have been well defined in vitro, the in vivo selectivity for recognition by GATA factors remains poorly characterized. Using ChIP-Seq, we identified the Dal80 GATA factor targets in yeast. Our data reveal Dal80 binding to a large set of promoters, sometimes independently of GATA sites, correlating with nitrogen- and/or Dal80-sensitive gene expression. Strikingly, Dal80 was also detected across the body of promoter-bound genes, correlating with high expression. Mechanistic single-gene experiments showed that Dal80 spreading across gene bodies requires active transcription. Consistently, Dal80 co-immunoprecipitated with the initiating and post-initiation forms of RNA Polymerase II. Our work suggests that GATA factors could play dual, synergistic roles during transcription initiation and post-initiation steps, promoting efficient remodeling of the gene expression program in response to environmental changes. Overall design: Strand-specific total RNA-Seq analysis in wild-type (WT) and dal80-delta (dal80) cells grown in glutamine- and/or proline-containing medium.
Transcription-dependent spreading of the Dal80 yeast GATA factor across the body of highly expressed genes.
Subject
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