Search results for "Peroxisome proliferator"
showing 10 items of 132 documents
Phosphorylation of peroxisome proliferator-activated receptor α in rat Fao cells and stimulation by ciprofibrate
1999
The basic mechanism(s) by which peroxisome proliferators activate peroxisome proliferator-activated receptors (PPARs) is (are) not yet fully understood. Given the diversity of peroxisome proliferators, several hypotheses of activation have been proposed. Among them is the notion that peroxisome proliferators could activate PPARs by changing their phosphorylation status. In fact, it is well known that several members of the nuclear hormone receptor superfamily are regulated by phosphorylation. In this report, we show that the rat Fao hepatic-derived cell line, known to respond to peroxisome proliferators, exhibited a high content of PPARalpha. Alkaline phosphatase treatment of Fao cell lysat…
The analysis of modified peroxisome proliferator responsive elements of the peroxisomal bifunctional enzyme in transfected HepG2 cells reveals two re…
1995
AbstractPeroxisome proliferators (PPs) are non-genotoxic carcinogens in rodents. They can induce the expression of numerous genes via the heterodimerization of two members of the steroid hormone receptor superfamily, called the peroxisome proliferator-activated receptor (PPAR) and the 9-cis retinoic acid receptor (RXR). Many of the PP responsive genes possess a peroxisome proliferator response element (PPRE) formed by two TGACCT-related motifs. The bifunctional enzyme (HD) PPRE contains 3 such motifs, creating DR1 and DR2 sequences. PPAR and RXR regulate transcription via the DR1 element while DR2 modulates the expression of the gene via auxiliary factors in HepG2 cells.
Functional characterization of a peroxisome proliferator response-element located in the intron 3 of rat peroxisomal thiolase B gene.
2003
Expression of the rat peroxisomal 3-ketoacyl-CoA thiolase gene B is induced by peroxisome proliferators. Although a sequence element like a peroxisome proliferator-activated receptor (PPAR)-binding site is located in the promoter region of this gene, we previously found that this element is competent for the activation by hepatocyte nuclear factor-4, but not functional with PPARalpha. We describe here a new peroxisome proliferator-response element located in the intron 3 (+1422/+1434) that binds in vitro the PPARalpha/retinoid X receptor alpha heterodimer and confers the induction by PPARalpha in transfection assays. We propose a model of regulation of the rat thiolase B gene involving thos…
Argan oil prevents down-regulation induced by endotoxin on liver fatty acid oxidation and gluconeogenesis and on peroxisome proliferator-activated re…
2015
In patients with sepsis, liver metabolism and its capacity to provide other organs with energetic substrates are impaired. This and many other pathophysiological changes seen in human patients are reproduced in mice injected with purified endotoxin (lipopolysaccharide, LPS). In the present study, down-regulation of genes involved in hepatic fatty acid oxidation (FAOx) and gluconeogenesis in mice exposed to LPS was challenged by nutritional intervention with Argan oil. Mice given a standard chow supplemented or not with either 6% (w/w) Argan oil (AO) or 6% (w/w) olive oil (OO) prior to exposure to LPS were explored for liver gene expressions assessed by mRNA transcript levels and/or enzyme a…
Hepatic steatosis and peroxisomal fatty acid beta-oxidation.
2012
Three subhepatocellular compartments concur for fatty acids degradation including ω-oxidation in endoplasmic reticulum and β-oxidation in both mitochondria and peroxisomes. Deficits affecting the peroxisomal physiology may be associated with multiple metabolic disturbances. Nowadays, a growing body of evidence underlines the key role of peroxisomal β-oxidation in the sensing of lipid metabolism through the production/degradation of some essential metabolites. Lessons from several mice models strengthen the link between fatty acid β-oxidation in peroxisomes and the nuclear hormone receptor Peroxisome Proliferator-Activated Receptor (PPAR)-α with an additional level of coregualtor complexity,…
PPARα/HNF4α Interplay on Diversified Responsive Elements. Relevance in the Regulation of Liver Peroxisomal Fatty Acid Catabolism
2012
In mammals, the liver is the major organ of fatty acid catabolism. This pathway is involved in both mitochondria and peroxisome. While mitochondria breaks down fatty acids with short, medium and long carbon chains, peroxisomes are involved in the catabolism of very long and branched chain fatty acids, which are degraded by three enzymes: acyl-CoA oxidase, multifunctional enzyme and thiolase enzyme. The active pathway results mainly from a tight transcriptional control of these gene-encoding enzymes. Two major nuclear receptors that are highly expressed in this organ are involved in this control, e.g. PPARα (peroxisome proliferator-activated receptor, α isoform) and HNF4α (hepatic nuclear fa…
Transcriptional and post-transcriptional analysis of peroxisomal protein encoding genes from rat treated with an hypolipemic agent, ciprofibrate
1995
The treatment of rats with ciprofibrate, a potent peroxisome proliferator, led to increased levels of the peroxisomal acyl-CoA oxidase (ACO) mRNA. How ciprofibrate functions to elevate ACO mRNA is not known. To help determine the mechanism of ciprofibrate action, in vitro transcription assays were performed. It was determined that ciprofibrate was responsible for a 3.5-fold stimulation of the rate of ACO transcription within 24 hr of ingestion. It was also observed that the transcription rate stimulation following a 2-week ciprofibrate treatment of Wistar rats was maintained following 4 weeks of ciprofibrate withdrawal. Re-introduction of the drug after the 4-week pause resulted in greater …
Influence of peroxisome proliferators on phosphoprotein levels in human and rat hepatic-derived cell lines.
1995
To elucidate the effect of peroxisome proliferators on the signal-transduction pathway, we have compared the effect of ciprofibrate, an hypolipaemic agent, on the overall phosphoprotein level between rat and human well differentiated hepatic derived cell lines. The phosphorylation status of several phosphoproteins in the rat Fao cell line was increased by the drug while no changes were observed in the human HepG2 cell line. In rat Fao cells, this increase, which is concentration and time dependent, can be as much as eightfold for 20-kDa and 22-kDa proteins. Wy-14,643, a non-fibrate molecule and a more potent peroxisome proliferator than ciprofibrate, increased the phosphorylation status of …
Peroxisome proliferator-activated receptor δ (PPARδ) activation protects H9c2 cardiomyoblasts from oxidative stress-induced apoptosis
2005
Activation of peroxisome proliferator-activated receptor alpha (PPARalpha) and PPARgamma plays beneficial roles in cardiovascular disorders such as atherosclerosis and heart reperfusion. Although PPARalpha and gamma have been documented to reduce oxidative stress in the vasculature and the heart, the role of PPARdelta remains poorly studied.We focused on PPARdelta function in the regulation of oxidative stress-induced apoptosis in the rat cardiomyoblast cell line H9c2. Using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we showed that PPARdelta is the predominantly expressed isotype whereas PPARalpha was weakly detected. By performing cell viability assays, we …
Age-dependent regulation of antioxidant genes by p38α MAPK in the liver
2018
p38α is a redox sensitive MAPK activated by pro-inflammatory cytokines and environmental, genotoxic and endoplasmic reticulum stresses. The aim of this work was to assess whether p38α controls the antioxidant defense in the liver, and if so, to elucidate the mechanism(s) involved and the age-related changes. For this purpose, we used liver-specific p38α-deficient mice at two different ages: young-mice (4 months-old) and old-mice (24 months-old). The liver of young p38α knock-out mice exhibited a decrease in GSH levels and an increase in GSSG/GSH ratio and malondialdehyde levels. However, old mice deficient in p38α had higher hepatic GSH levels and lower GSSG/GSH ratio than young p38α knock-…