scholarly journals DHA Upregulates FADS2 Expression in Primary Cortical Astrocytes Exposed to Vitamin A

2018 ◽  
pp. 663-668 ◽  
Author(s):  
B. DZIEDZIC ◽  
D. BEWICZ-BINKOWSKA ◽  
E. ZGORZYNSKA ◽  
D. STULCZEWSKI ◽  
L. WIETESKA ◽  
...  
Keyword(s):  
Gene Expression ◽  
Vitamin A ◽  
Dietary Fatty Acids ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Gene Encoding ◽  
Protein Levels ◽  
Peroxisome Proliferator Activated Receptors ◽  
X Receptors ◽  
Δ6 Desaturase

The fads2 gene encoding Δ6-desaturase, the rate-limiting enzyme of the LCPUFA biosynthesis is expressed in astrocytes. Dietary fatty acids, which cross the blood-brain barrier, may regulate the transcription of lipogenic enzymes through activation of transcription factors such as peroxisome proliferator-activated receptors (PPARs). The PPARs form the transcription complex with retinoid X receptors (RXRs) that are activated by 9-cis retinoic acid, a metabolite of vitamin A (VA). The study examines whether challenge of astrocytes with VA, prior 24-h treatment with palmitic acid (PA), α-linolenic acid (ALA) or docosahexaenoic acid (DHA) has the effect on the FADS2 expression. RT-qPCR showed that in astrocytes not challenged with VA, PA increased fads2 gene expression and DHA decreased it. However, in VA-primed astrocytes, PA doubled the FADS2 mRNA levels, while DHA increased fads2 gene expression, oppositely to non-primed cells. Furthermore, similar changes were seen in VA-primed astrocytes with regard to Δ6-desaturase protein levels following PA and DHA treatment. ALA did not have any effect on the FADS2 mRNA and protein levels in either VA-primed or non-primed astrocytes. These findings indicate that in the presence of vitamin A, DHA upregulates fads2 gene expression in astrocytes.

scholarly journals Regulation of Peroxisome Proliferator-Activated Receptors by E6-Associated Protein

PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Lakshmi Gopinathan ◽  
Daniel B. Hannon ◽  
Russell W. Smith ◽  
Jeffrey M. Peters ◽  
John P. Vanden Heuvel
Keyword(s):  
Ubiquitin Ligase ◽  
Target Genes ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Independent Manner ◽  
Coordinate Regulation ◽  
Protein Levels ◽  
Ubiquitin Ligase Activity ◽  
Peroxisome Proliferator Activated Receptors

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors (NRs) that regulate genes involved in lipid and glucose metabolism. PPAR activity is regulated by interactions with cofactors and of interest are cofactors with ubiquitin ligase activity. The E6-associated protein (E6-AP) is an E3 ubiquitin ligase that affects the activity of other NRs, although its effects on PPARs have not been examined. E6-AP inhibited the ligand-independent transcriptional activity of PPARαand PPARβ, with marginal effects on PPARγ, and decreased basal mRNA levels of PPARαtarget genes. Inhibition of PPARαactivity required the ubiquitin ligase function of E6-AP, but occurred in a proteasome-independent manner. PPARαinteracted with E6-AP, and in mice treated with PPARαagonist clofibrate, mRNA and protein levels of E6-AP were increased in wildtype, but not in PPARαnull mice, indicating a PPARα-dependent regulation. These studies suggest coordinate regulation of E6-AP and PPARα, and contribute to our understanding of the role of PPARs in cellular metabolism.

scholarly journals Noradrenaline represses PPAR (peroxisome-proliferator-activated receptor) γ2 gene expression in brown adipocytes: intracellular signalling and effects on PPARγ2 and PPARγ1 protein levels

2004 ◽  
Vol 382 (2) ◽  
pp. 597-606 ◽  
Author(s):  
Eva M. LINDGREN ◽  
Ronni NIELSEN ◽  
Natasa PETROVIC ◽  
Anders JACOBSSON ◽  
Susanne MANDRUP ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Down Regulation ◽  
Brown Adipocytes ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Pparγ Gene ◽  
Kinase A

PPAR (peroxisome-proliferator-activated receptor) γ is expressed in brown and white adipose tissues and is involved in the control of differentiation and proliferation. Noradrenaline stimulates brown pre-adipocyte proliferation and brown adipocyte differentiation. The aim of the present study was thus to investigate the influence of noradrenaline on PPARγ gene expression in brown adipocytes. In primary cultures of brown adipocytes, PPARγ2 mRNA levels were 20-fold higher than PPARγ1 mRNA levels. PPARγ expression occurred during both the proliferation and the differentiation phases, with the highest mRNA levels being found at the time of transition between the phases. PPARγ2 mRNA levels were downregulated by noradrenaline treatment (EC50, 0.1 μM) in both proliferative and differentiating cells, with a lagtime of 1 h and lasting up to 4 h, after which expression gradually recovered. The down-regulation was β-adrenoceptor-induced and intracellularly mediated via cAMP and protein kinase A; the signalling pathway did not involve phosphoinositide 3-kinase, Src, p38 mitogen-activated protein kinase or extracellular-signal-regulated kinases 1 and 2. Treatment of the cells with the protein synthesis inhibitor cycloheximide not only abolished the noradrenaline-induced down-regulation of PPARγ2 mRNA, but also in itself induced PPARγ2 hyperexpression. The down-regulation was probably the result of suppression of transcription. The down-regulation of PPARγ2 mRNA resulted in similar down-regulation of PPARγ2 and phosphoPPARγ2 protein levels. Remarkably, the level of PPARγ1 protein was similar to that of PPARγ2 (despite almost no PPARγ1 mRNA), and the down-regulation by noradrenaline demonstrated similar kinetics to that of PPARγ2; thus PPARγ1 was apparently translated from the PPARγ2 template. It is suggested that β-adrenergic stimulation via cAMP and protein kinase A represses PPARγ gene expression, leading to reduction of PPARγ2 mRNA levels, which is then reflected in down-regulated levels of PPARγ2, phosphoPPARγ2 and PPARγ1.

Metallothionein gene expression and secretion in white adipose tissue

2000 ◽  
Vol 279 (6) ◽  
pp. R2329-R2335 ◽  
Author(s):  
Paul Trayhurn ◽  
Jacqueline S. Duncan ◽  
Anne M. Wood ◽  
John H. Beattie
Keyword(s):  
Gene Expression ◽  
Molecular Weight ◽  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Stromal Vascular Fraction ◽  
Low Molecular Weight ◽  
Secretory Product ◽  
Mrna Levels ◽  
Gene Encoding ◽  
Adrenoceptor Agonist

White adipose tissue (WAT) has been examined to determine whether the gene encoding metallothionein (MT), a low-molecular-weight stress response protein, is expressed in the tissue and whether MT may be a secretory product of adipocytes. The MT-1 gene was expressed in epididymal WAT, with MT-1 mRNA levels being similar in lean and obese ( ob/ ob) mice. MT-1 mRNA was found in each of the main adipose tissue sites (epididymal, perirenal, omental, subcutaneous), and there was no major difference between depots. Separation of adipocytes from the stromal-vascular fraction of WAT indicated that the MT gene (MT-1 and MT-2) was expressed in adipocytes themselves. Treatment of mice with zinc had no effect on MT-1 mRNA levels in WAT, despite strong induction of MT-1 expression in the liver. MT-1 gene expression in WAT was also unaltered by fasting or norepinephrine. However, administration of a β3-adrenoceptor agonist, BRL-35153A, led to a significant increase in MT-1 mRNA. On differentiation of fibroblastic preadipocytes to adipocytes in primary culture, MT was detected in the medium, suggesting that the protein may be secreted from WAT. It is concluded that WAT may be a significant site of MT production; within adipocytes, MT could play an antioxidant role in protecting fatty acids from damage.

scholarly journals Adipose Tissue Expansion by Overfeeding Healthy Men Alters Iron Gene Expression

2018 ◽  
Vol 104 (3) ◽  
pp. 688-696 ◽  
Author(s):  
Berenice Segrestin ◽  
José Maria Moreno-Navarrete ◽  
Kevin Seyssel ◽  
Maud Alligier ◽  
Emmanuelle Meugnier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Serum Iron ◽  
Tissue Expansion ◽  
Lipid Storage ◽  
Mrna Levels ◽  
Intracellular Iron ◽  
Gene Encoding ◽  
Iron Storage ◽  
Healthy Men

Abstract Context Iron overload has been associated with greater adipose tissue (AT) depots. We retrospectively studied the potential interactions between iron and AT during an experimental overfeeding in participants without obesity. Methods Twenty-six participants (mean body mass index ± SD, 24.7 ± 3.1 kg/m2) underwent a 56-day overfeeding (+760 kcal/d). Serum iron biomarkers (ELISA), subcutaneous AT (SAT) gene expression, and abdominal AT distribution assessed by MRI were analyzed at the beginning and the end of the intervention. Results Before intervention: SAT mRNA expression of the iron transporter transferrin (Tf) was positively correlated with the expression of genes related to lipogenesis (lipin 1, ACSL1) and lipid storage (SCD). SAT expression of the ferritin light chain (FTL) gene, encoding ferritin (FT), an intracellular iron storage protein, was negatively correlated to SREBF1, a gene related to lipogenesis. Serum FT (mean, 92 ± 57 ng/mL) was negatively correlated with the expression of SAT genes linked to lipid storage (SCD, DGAT2) and to lipogenesis (SREBF1, ACSL1). After intervention: Overfeeding led to a 2.3 ± 1.3-kg weight gain. In parallel to increased expression of lipid storage–related genes (mitoNEET, SCD, DGAT2, SREBF1), SAT Tf, SLC40A1 (encoding ferroportin 1, a membrane iron export channel) and hephaestin mRNA levels increased, whereas SAT FTL mRNA decreased, suggesting increased AT iron requirement. Serum FT decreased to 67 ± 43 ng/mL. However, no significant associations between serum iron biomarkers and AT distribution or expansion were observed. Conclusion In healthy men, iron metabolism gene expression in SAT is associated with lipid storage and lipogenesis genes expression and is modulated during a 56-day overfeeding diet.

Peroxisome proliferator-activated receptors: Lipid binding proteins controling gene expression

2002 ◽  
pp. 131-138
Author(s):  
Marc van Bilsen ◽  
Ger J. van der Vusse ◽  
Andries J. Gilde ◽  
Martijn Lindhout ◽  
Karin A. J. M. van der Lee
Keyword(s):  
Gene Expression ◽  
Binding Proteins ◽  
Lipid Binding ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptors ◽  
Lipid Binding Proteins

scholarly journals Peroxisome Proliferator Activated Receptors and Lipoprotein Metabolism

PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-11 ◽  
Author(s):  
Sander Kersten
Keyword(s):  
Lipoprotein Metabolism ◽  
Physiological Role ◽  
Density Lipoprotein ◽  
Hdl Cholesterol ◽  
Molecular Target ◽  
Plasma Triglyceride ◽  
Dietary Fatty Acids ◽  
Plasma Lipoproteins ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptors

Plasma lipoproteins are responsible for carrying triglycerides and cholesterol in the blood and ensuring their delivery to target organs. Regulation of lipoprotein metabolism takes place at numerous levels including via changes in gene transcription. An important group of transcription factors that mediates the effect of dietary fatty acids and certain drugs on plasma lipoproteins are the peroxisome proliferator activated receptors (PPARs). Three PPAR isotypes can be distinguished, all of which have a major role in regulating lipoprotein metabolism. PPARαis the molecular target for the fibrate class of drugs. Activation of PPARαin mice and humans markedly reduces hepatic triglyceride production and promotes plasma triglyceride clearance, leading to a clinically significant reduction in plasma triglyceride levels. In addition, plasma high-density lipoprotein (HDL)-cholesterol levels are increased upon PPARαactivation in humans. PPARγis the molecular target for the thiazolidinedione class of drugs. Activation of PPARγin mice and human is generally associated with a modest increase in plasma HDL-cholesterol and a decrease in plasma triglycerides. The latter effect is caused by an increase in lipoprotein lipase-dependent plasma triglyceride clearance. Analogous to PPARα, activation of PPARβ/δleads to increased plasma HDL-cholesterol and decreased plasma triglyceride levels. In this paper, a fresh perspective on the relation between PPARs and lipoprotein metabolism is presented. The emphasis is on the physiological role of PPARs and the mechanisms underlying the effect of synthetic PPAR agonists on plasma lipoprotein levels.

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