Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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C57BL/6N Mice on High Fat Diet Display Reduced Intestinal and Hepatic Cholesterol Levels despite a Plasma Hypercholesterolemia

ABSTRACT: Background Small intestine and liver greatly contribute to whole body lipid, cholesterol and phospholipid metabolism but to which extent cholesterol and phospholipid handling in these tissues is affected by high fat Western-style obesogenic diets remains to be defined. We therefore quantified cholesterol and phospholipid concentrations in intestine and liver and determined fecal neutral sterol and bile acid excretion in C57Bl/6N mice fed for 12 weeks either a cholesterol-free high carbohydrate control diet or a high fat diet containing 0.03 % (w/w) cholesterol. To identify underlying mechanisms of dietary adaptation in intestine and liver, changes in gene expression were assessed by microarray and qPCR profiling, respectively. Results Animals on high fat diet showed increased plasma cholesterol levels, associated with the higher dietary cholesterol supply, yet, significantly reduced cholesterol levels were found in intestine and liver. Transcript profiling revealed evidence that expression of numerous genes involved in cholesterol synthesis and uptake via LDL, but also in phospholipid metabolism, underwent compensatory regulations in both tissues. Alterations in glycerophospholipid metabolism were confirmed at the metabolite level by phospolipid profiling via mass spectrometry. Conclusions Our findings suggest that intestine and liver react to a high dietary fat intake by an activation of de novo cholesterol synthesis and other cholesterol-saving mechanisms, as well as with major changes in phospholipid metabolism, to accommodate to the fat load. The proximal part of the intestine of mice fed either a control or a high fat diet were analyzed. 5 replicates each.

ORGANISM(S): Mus musculus

SUBMITTER: Charles Desmarchelier

PROVIDER: E-GEOD-29748 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Renal hypoxia is widespread in acute kidney injury (AKI) of various aetiologies. Hypoxia adaptation, conferred through the hypoxia-inducible factor (HIF), appears to be insufficient. Here we show that HIF activation in renal tubules through Pax8-rtTA-based inducible knockout of von Hippel-Lindau protein (VHL-KO) protects from rhabdomyolysis-induced AKI. In this model, histological observations indicate that injury mainly affects proximal convoluted tubules, with 5% necrosis at d1 and 40% necrosis at d2. HIF-1alpha up-regulation in distal tubules reflects renal hypoxia. However, lack of HIF in proximal tubules suggests insufficient adaptation by HIF. AKI in VHL-KO mice leads to prominent HIF activation in all nephron segments, as well as to reduced serum creatinine, serum urea, tubular necrosis, and apoptosis marker caspase-3 protein. At d1 after rhabdomyolysis, when tubular injury is potentially reversible, HIF mediated protection in AKI is associated with activated glycolysis, cellular glucose uptake and utilization, autophagy, vasodilation, and proton removal as demonstrated by qPCR, pathway enrichment analysis and immunohistochemistry. Together, our data provide evidence for a HIF-orchestrated multi-level shift towards glycolysis as a major mechanism for protection against acute tubular injury. All experiments were carried out in transgenic mice in which selective renal tubular VHL knockout (VHL-KO) was inducible by doxycycline (Reference: Mathia S, Paliege A, Koesters R, Peters H, Neumayer HH, Bachmann S, Rosenberger C. Action of hypoxia-inducible factor in liver and kidney from mice with Pax8-rtTA-based deletion of von Hippel-Lindau protein. Acta Physiol (Oxf). 2013; 207(3):565-76.). Four groups of animals were used: 1) controls: untreated mice; 2) VHL-KO: injected with doxycycline (0.1 mg per 10 g body weight SC), 4 days prior to sacrifice; 3) AKI: rhabdomyolysis; 4) VHL-KO/AKI: doxycycline plus rhabdomyolysis. To induce AKI, 50% glycerol (0.05 ml per 10 g body weight) was injected IM into the left hind limb under isoflurane narcosis. Drinking water was withdrawn between 20 h prior and 24 h after glycerol injection.

Project description:Our present study reveals significant decelerating effects on senescence processes in middle-aged SAMP1 mice supplemented for 6 or 14 months with the reduced form (QH2, 500 mg/ kg BW/ day) of coenzyme Q10 (CoQ10). To unravel molecular mechanisms of these CoQ10 effects, a genome-wide transcript profiling in liver, heart, brain and kidney of SAMP1 mice supplemented with the reduced (QH2) or oxidized form of CoQ10 (Q10) was performed. Liver seems to be the main target tissue of CoQ10 intervention, followed by kidney, heart and brain. Stringent evaluation of the resulting data revealed that QH2 has a stronger impact on gene expression than Q10, which was primarily due to differences in the bioavailability. Indeed, we found that QH2 supplementation was more effective than Q10 to increase levels of CoQ10 in the liver of SAMP1 mice (54.92-fold and 30.36-fold, respectively). To identify functional and regulatory connections of the âtop 50â (p < 0.05) up- and down-regulated QH2-sensitive transcripts in liver (fold changes ranging from 21.24 to -6.12), text mining analysis (Genomatix BiblioSphere, GFG level B3) was used. Hereby, we identified 11 QH2-sensitive genes which are regulated by PPAR-Î± and are primarily involved in cholesterol synthesis (e.g. HMGCS1, HMGCL, HMGCR), fat assimilation (FABP5), lipoprotein metabolism (PLTP) and inflammation (STAT-1). Thus, we provide evidence that QH2 is involved in the reduction of fat and cholesterol synthesis via modulation of the PPAR-Î± signalling pathway. These data may explain, at least in part, the observed effects on decelerated age-dependent degeneration processes in QH2-supplemented SAMP1 mice. Whole genome expression profiles were analysed from liver, heart, brain and kidney (each analyzed separately) of SAMP1 mice supplemented with QH2, Q10 or a control diet. From every experimental group, three mice each were sacrificed 6 or 14 months after supplementation, resulting in a total of 72 microarrays.

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C57BL/6N Mice on High Fat Diet Display Reduced Intestinal and Hepatic Cholesterol Levels despite a Plasma Hypercholesterolemia

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