scholarly journals Interaction of the peroxisome proliferator-activated receptor alpha with the retinoid X receptor alpha unmasks a cryptic peroxisome proliferator response element that overlaps an ARP-1-binding site in the CYP4A6 promoter.

1994 ◽  
Vol 269 (27) ◽  
pp. 18083-18089 ◽  
Author(s):  
C.N. Palmer ◽  
M.H. Hsu ◽  
A.S. Muerhoff ◽  
K.J. Griffin ◽  
E.F. Johnson
Keyword(s):  
Binding Site ◽  
Retinoid X Receptor ◽  
Peroxisome Proliferator ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Receptor Alpha ◽  
Peroxisome Proliferator Response Element ◽  
Retinoid X Receptor Alpha

scholarly journals Identification and characterization of DNA elements implicated in the regulation of CYP4A1 transcription

1995 ◽  
Vol 306 (2) ◽  
pp. 473-479 ◽  
Author(s):  
T C Aldridge ◽  
J D Tugwood ◽  
S Green
Keyword(s):  
Regulatory Sequences ◽  
Peroxisome Proliferator ◽  
Ppar Alpha ◽  
Peroxisome Proliferator Activated Receptor ◽  
Receptor Alpha ◽  
Pleiotropic Action ◽  
Dna Elements ◽  
Peroxisome Proliferator Response Element ◽  
Retinoid X Receptor Alpha

We have identified a peroxisome proliferator response element (PPRE) approx. 4300 nucleotide upstream of the rat cytochrome P-450 CYP4A1 gene. Two members of the steroid-hormone-receptor superfamily, the peroxisome proliferator-activated receptor-alpha (PPAR alpha) and the retinoid X receptor-alpha (RXR alpha), bind specifically to this element as a heterodimer, and this element confers responsiveness to the peroxisome proliferator Wyeth-14,643 when tested in co-transfection assays. A second element, located 35 nucleotides further upstream, fails to bind PPAR alpha/RXR alpha heterodimers and is unresponsive to Wy-14,643 in co-transfection assays. Both elements are, however, responsive to 9-cis-retinoic acid in the presence of RXR alpha, when tested in the co-transfection assay. As RXR alpha fails to bind to either element as a homodimer, we suggest that RXR alpha interacts with PPAR alpha to regulate transcription via the proximal element, and interacts with some other cellular factor to regulate transcription via the more distal element. This is consistent with previous reports that a number of peroxisome proliferator-regulated genes contain PPRE-like elements as part of their regulatory sequences, which may be recognized by several receptor combinations. This provides further evidence that PPARs and their co-factors are important in mediating the pleiotropic action of peroxisome proliferators.

scholarly journals Retinoids increase human apolipoprotein A-11 expression through activation of the retinoid X receptor but not the retinoic acid receptor.

1996 ◽  
Vol 16 (7) ◽  
pp. 3350-3360 ◽  
Author(s):  
N Vu-Dac ◽  
K Schoonjans ◽  
V Kosykh ◽  
J Dallongeville ◽  
R A Heyman ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Primary Cultures ◽  
Retinoid X Receptor ◽  
Site Directed Mutagenesis ◽  
Transcriptional Level ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Reporter Construct ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor

Considering the link between plasma high-density lipoprotein (HDL) cholesterol levels and a protective effect against coronary artery disease as well as the suggested beneficial effects of retinoids on the production of the major HDL apolipoprotein (apo), apo A-I, the goal of this study was to analyze the influence of retinoids on the expression of apo A-II, the other major HDL protein. Retinoic acid (RA) derivatives have a direct effect on hepatic apo A-II production, since all-trans (at) RA induces apo A-II mRNA levels and apo A-II secretion in primary cultures of human hepatocytes. In the HepG2 human hepatoblastoma cell line, both at-RA and 9-cis RA as well as the retinoid X receptor (RXR)-specific agonist LGD 1069, but not the RA receptor (RAR) agonist ethyl-p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-l-pro penyl]-benzoic acid (TTNPB), induce apo A-II mRNA levels. Transient-transfection experiments with a reporter construct driven by the human apo A-II gene promoter indicated that 9-cis RA and at-RA, as well as the RXR agonists LGD 1069 and LG 100268, induced apo A-II gene expression at the transcriptional level. Only minimal effects of the RAR agonist TTNPB were observed on the apo A-II promoter reporter construct. Unilateral deletions and site-directed mutagenesis identified the J site of the apo A-II promoter mediating the responsiveness to RA. This element contains two imperfect half-sites spaced by 1 oligonucleotide. Cotransfection assays in combination with the use of RXR or RAR agonists showed that RXR but not RAR transactivates the apo A-II promoter through this element. By contrast, RAR inhibits the inductive effects of RXR on the apo A-II J site in a dose-dependent fashion. Gel retardation assays demonstrated that RXR homodimers bind, although with a lower affinity than RAR-RXR heterodimers, to the AH-RXR response element. In conclusion, retinoids induce hepatic apo A-II production at the transcriptional level via the interaction of RXR with an element in the J site containing two imperfect half-sites spaced by 1 oligonucleotide, thereby demonstrating an important role of RXR in controlling human lipoprotein metabolism. Since the J site also confers responsiveness of the apo A-II gene to fibrates and fatty acids via the activation of peroxisome proliferator-activated receptor-RXR heterodimers, this site can be considered a plurimetabolic response element.

scholarly journals Fenofibrate Reduces the Severity of Neuroretinopathy in a Type 2 Model of Diabetes without Inducing Peroxisome Proliferator-Activated Receptor Alpha-Dependent Retinal Gene Expression

2020 ◽  
Vol 10 (1) ◽  
pp. 126
Author(s):  
Jennifer M. Enright ◽  
Sheng Zhang ◽  
Christina Thebeau ◽  
Emily Siebert ◽  
Alexander Jin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Elevated Serum ◽  
Oscillatory Potentials ◽  
Luciferase Reporter ◽  
Peroxisome Proliferator ◽  
Serum Triglycerides ◽  
Peroxisome Proliferator Activated Receptor ◽  
Receptor Alpha ◽  
Peroxisome Proliferator Response Element

Fenofibrate slows the progression of clinical diabetic retinopathy (DR), but its mechanism of action in the retina remains unclear. Fenofibrate is a known agonist of peroxisome proliferator-activated receptor alpha (PPARα), a transcription factor critical for regulating metabolism, inflammation and oxidative stress. Using a DR mouse model, db/db, we tested the hypothesis that fenofibrate slows early DR progression by activating PPARα in the retina. Relative to healthy littermates, six-month-old db/db mice exhibited elevated serum triglycerides and cholesterol, retinal gliosis, and electroretinography (ERG) changes including reduced b-wave amplitudes and delayed oscillatory potentials. These pathologic changes in the retina were improved by oral fenofibrate. However, fenofibrate did not induce PPARα target gene expression in whole retina or isolated Müller glia. The capacity of the retina to respond to PPARα was further tested by delivering the PPARα agonist GW590735 to the intraperitoneal or intravitreous space in mice carrying the peroxisome proliferator response element (PPRE)-luciferase reporter. We observed strong induction of the reporter in the liver, but no induction in the retina. In summary, fenofibrate treatment of db/db mice prevents the development of early DR but is not associated with induction of PPARα in the retina.

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