scholarly journals Retinoic acid receptor γ 2 gene expression is up-regulated by retinoic acid in 3T3-L1 preadipocytes

1993 ◽  
Vol 293 (3) ◽  
pp. 807-812 ◽  
Author(s):  
Y Kamei ◽  
T Kawada ◽  
R Kazuki ◽  
E Sugimoto

Retinoids, especially all-trans retinoic acid (RA), have been shown to inhibit the differentiation of preadipose cells. In the present study, the expression of retinoic acid receptors (RAR alpha, beta and gamma) and retinoid X receptors (RXR alpha, beta and gamma) was examined by Northern blot analysis in rat adipose tissue and mouse 3T3-L1 adipose cells. The adipose tissue and/or 3T3-L1 cells expressed mRNAs for a number of nuclear retinoid receptors, including RAR alpha, beta and gamma, and RXR alpha, beta and gamma. RAR alpha, RAR gamma, RXR alpha and RXR beta mRNAs were abundant in adipose tissue and 3T3-L1 cells. RXR gamma mRNA was detected in adipose tissue but not in 3T3-L1 cells. Treatment of 3T3-L1 cells with 1 microM RA led to a 4-5-fold increase in the RAR gamma mRNA level, but only a trace amount of RAR beta mRNA was detected. RAR gamma mRNA expression was rapidly (within 2 h) induced by physiological concentrations of RA in a dose-dependent manner. The response of RAR gamma mRNA expression to RA was reversible; rapid disappearance of RAR gamma mRNA occurred on RA removal. In addition, the induction of RAR gamma expression did not require de novo protein synthesis, but was completely abolished by an inhibitor of RNA synthesis. Using RAR gamma 1 and gamma 2 isoform-specific probes, the patterns of RAR gamma 1 and gamma 2 mRNA expression in 3T3-L1 cells in the presence and absence of RA were examined. RAR gamma 1 mRNA was detected in 3T3-L1 cells but was not affected by RA treatment; however, RAR gamma 2 mRNA was strongly induced by RA.

2004 ◽  
Vol 33 (1) ◽  
pp. 11-19 ◽  
Author(s):  
RY Li ◽  
HD Song ◽  
WJ Shi ◽  
SM Hu ◽  
YS Yang ◽  
...  

In addition to serving as a fat depot, adipose tissue is also considered as an important endocrine organ that synthesizes and secretes a number of factors. Leptin is an adipocyte-derived hormone that plays a vital role in energy balance. Expression of leptin is regulated by dietary status and hormones. In the present study, we report that galanin, an orexigenic peptide, inhibits leptin expression and secretion in rat adipose tissue and in 3T3-L1 adipocytes. Treatment with galanin (25 micro g/animal) induced approximately 46% down-regulation of leptin secretion at 15 min, followed by 40, 37 and 47% decreases in leptin secretion at 1, 2 and 4 h respectively. Although Northern blot analysis of adipose tissue from the same animals showed that leptin mRNA expression in adipose tissue was unaffected by galanin treatment for 2 h, galanin treatment for 4 h led to decline of leptin mRNA expression in a dose-dependent manner. Meanwhile, treating the rats with galanin had no effect on leptin mRNA expression in the hypothalamus. The inhibitory action of the galanin on leptin mRNA and protein levels was also observed in vitro. When incubated with 10 nM galanin for 48 h, leptin mRNA expression and protein secretion also decreased in 3T3-L1 adipocytes. On the other hand, galanin was found not only to express in rat adipose tissue, but also to increase about 8-fold after fasting. Based on these data, we speculate that increased galanin expression in rat adipose tissue after fasting may be involved in reducing leptin expression and secretion in fasting rats.


2004 ◽  
Vol 287 (3) ◽  
pp. E424-E430 ◽  
Author(s):  
Zhibin He ◽  
Tao Jiang ◽  
Zhuowei Wang ◽  
Moshe Levi ◽  
Jinping Li

Carbohydrate response element-binding protein (ChREBP) is a rat homolog of human Williams-Beuren syndrome region 14 and a member of the basic helix-loop-helix leucine zipper transcription factor family. Its activation was found to be inducible by carbohydrate in the liver nuclear extracts from rats fed a high-sucrose diet. ChREBP is able to bind to the carbohydrate response element on the promoter of L-type pyruvate kinase and initiate the gene transcription. The detailed expression profile and transcriptional regulation of the ChREBP gene in adipocytes have not been characterized. In the present study, we provide evidence showing that 1) the ChREBP gene is expressed in differentiated 3T3-L1 adipocytes and rat adipose tissue; 2) insulin, glucose, and the antidiabetic agent troglitazone can significantly upregulate the gene expression of ChREBP in 3T3-L1 adipocytes, whereas free fatty acids suppress its expression in this cell type; 3) fasting followed by refeeding with a high-carbohydrate diet resulted in a 10-fold increase of ChREBP mRNA level in rat adipose tissue; and 4) ChREBP expression in adipose tissue is not significantly affected by the diabetic state. Taken together, the results we present are consistent with the idea that ChREBP is an important modulator of adipocyte biology and that its expression in adipose tissue is subject to combined regulation by glucose and insulin in vivo. The induction of ChREBP may serve as a novel pharmacological pathway for troglitazone-mediated hypoglycemic effects in vivo.


2010 ◽  
Vol 146 (6) ◽  
Author(s):  
Fabian Hartmann ◽  
Maria Kosmidis ◽  
Beda Mühleisen ◽  
Lars E. French ◽  
Günther F. L. Hofbauer

2000 ◽  
Vol 20 (3) ◽  
pp. 957-970 ◽  
Author(s):  
Bingzhen Lin ◽  
Guo-quan Chen ◽  
Dongmei Xiao ◽  
Siva Kumar Kolluri ◽  
Xihua Cao ◽  
...  

ABSTRACT Retinoic acid receptor β (RARβ) plays a critical role in mediating the anticancer effects of retinoids. Expression of RARβ is highly induced by retinoic acid (RA) through a RA response element (βRARE) that is activated by heterodimers of RARs and retinoid X receptors (RXRs). However, RARβ induction is often lost in cancer cells despite expression of RARs and RXRs. In this study, we provide evidence that orphan receptor COUP-TF is required for induction of RARβ expression, growth inhibition, and apoptosis by RA in cancer cells. Expression of COUP-TF correlates with RARβ induction in a variety of cancer cell lines. In addition, stable expression of COUP-TF in COUP-TF-negative cancer cells restores induction of RARβ expression, growth inhibition, and apoptosis by RA, whereas inhibition of COUP-TF by expression of COUP-TF antisense RNA represses the RA effects. In a transient transfection assay, COUP-TF strongly induced transcriptional activity of the RARβ promoter in a RA- and RARα-dependent manner. By mutation analysis, we demonstrate that the effect of COUP-TF requires its binding to a DR-8 element present in the RARβ promoter. The binding of COUP-TF to the DR-8 element synergistically increases the RA-dependent RARα transactivation function by enhancing the interaction of RARα with its coactivator CREB binding protein. These results demonstrate that COUP-TF, by serving as an accessory protein for RARα to induce RARβ expression, plays a critical role in regulating the anticancer activities of retinoids.


1990 ◽  
Vol 10 (1) ◽  
pp. 391-396
Author(s):  
L Hu ◽  
L J Gudas

Retinoic acid (RA) receptor alpha (RAR alpha) and RAR gamma steady-state mRNA levels remained relatively constant over time after the addition of RA to F9 teratocarcinoma stem cells. In contrast, the steady-state RAR beta mRNA level started to increase within 12 h after the addition of RA and reached a 20-fold-higher level by 48 h. This RA-associated RAR beta mRNA increase was not prevented by protein synthesis inhibitors but was prevented by the addition of cyclic AMP analogs. In the presence of RA, cyclic AMP analogs also greatly reduced the RAR alpha and RAR gamma mRNA levels, even though cyclic AMP analogs alone did not alter these mRNA levels. The addition of either RA or RA plus cyclic AMP analogs did not result in changes in the three RAR mRNA half-lives. These results suggest that agents which elevate the internal cyclic AMP concentration may also affect the cellular response to RA by altering the expression of the RARs.


2002 ◽  
Vol 80 (8) ◽  
pp. 777-782 ◽  
Author(s):  
Masa-aki Hattori ◽  
Yukio Kato ◽  
Noboru Fujihara

The presence of endothelial nitric oxide synthase (eNOS) has been found in porcine oocytes, but its mRNA and protein levels remain relatively constant during hormonal stimulation. The present study was designed to determine the effect of retinoic acid on eNOS regulation in porcine oocytes during follicle-stimulating hormone (FSH) stimulation. Cumulus–oocyte complexes (COCs), prepared from small antral follicles of immature porcine ovaries, were cultured for 15 h and treated with FSH for an additional 48 h. eNOS mRNA and its protein were analyzed by reverse transcription – polymerase chain reaction and Western blotting, respectively. Retinoic acid had an inhibitory effect on the level of oocyte eNOS mRNA in a dose-dependent manner if COCs were exposed to retinoic acid before FSH stimulation. The inhibition of FSH action was reflected in a decrease in expression of c-fos mRNA. eNOS protein also decreased to approximately 50% of the control after exposure to 10 μM retinoic acid. However, the ability of NO synthesis was abolished in the oocytes prepared from retinoic acid pretreated COCs. These results suggest that retinoic acid has a strong inhibitory action on eNOS mRNA level and NO synthesis in the porcine oocyte.Key words: oocyte, retinoic acid, NO synthesis, eNOS, RT–PCR.


Endocrinology ◽  
2009 ◽  
Vol 150 (9) ◽  
pp. 4260-4269 ◽  
Author(s):  
Eiji Munetsuna ◽  
Yasushi Hojo ◽  
Minoru Hattori ◽  
Hirotaka Ishii ◽  
Suguru Kawato ◽  
...  

Abstract The hippocampus is essentially involved in learning and memory processes. Its functions are affected by various neuromodulators, including 17β-estradiol, testosterone, and retinoid. Brain-synthesized steroid hormones act as autocrine and paracrine modulators. The regulatory mechanism underlying brain steroidogenesis has not been fully elucidated. Synthesis of sex steroids in the gonads is stimulated by retinoic acids. Therefore, we examined the effects of retinoic acids on estradiol and testosterone biosynthesis in the rat hippocampus. We used cultured hippocampal slices from 10- to 12-d-old male rats to investigate de novo steroidogenesis. The infant rat hippocampus possesses mRNAs for steroidogenic enzymes and retinoid receptors. Slices were used after 24 h of preculture to obtain maximal steroidogenic activity because steroidogenesis in cultured slices decreases with time. The mRNA levels for P45017α, P450 aromatase and estrogen receptor-β in the slices were increased by treatment with 9-cis-retinoic acid but not by all-trans-isomer. The magnitude of stimulation and the shape of the dose-response curve for the mRNA level for P45017α were similar to those for cellular retinoid binding protein type 2, the transcription of which is activated by retinoid X receptor signaling. 9-cis-Retinoic acid also induced a 1.7-fold increase in the protein content of P45017α and a 2-fold increase in de novo synthesis of 17β-estradiol and testosterone. These steroids may be synthesized from a steroid precursor(s), such as pregnenolone or other steroids, or from cholesterol, as so-called neurosteroids. The stimulation of estradiol and testosterone synthesis by 9-cis-retinoic acid might be caused by activation of P45017α transcription via retinoid X receptor signaling.


Blood ◽  
1999 ◽  
Vol 94 (4) ◽  
pp. 1348-1358 ◽  
Author(s):  
Soheil Naderi ◽  
Heidi Kiil Blomhoff

The mechanisms underlying the growth-inhibitory effect of retinoids on normal human B lymphocytes are not well understood. We addressed this issue by examining the effect of retinoic acid on the cell cycle machinery involved in G1/S transition. When retinoic acid was administered to B cells stimulated into mid to late G1 by anti-IgM antibodies (anti-μ) and Staphylococcus aureus crude cell suspension (SAC), the phosphorylation of pRB required for S-phase entry was prevented in a time- and dose-dependent manner. Thus, 2-hour treatment with retinoic acid at the optimal concentration of 1 μmol/L prevented phosphorylation of pRB, and effects were noted at concentrations as low as 10 nmol/L. Based on our results, we suggest that the rapid effect of retinoic acid on pRB phosphorylation is due primarily to the reduced expression of cyclin E and cyclin A in late G1. This could lead to the diminished cyclin E– and cyclin A–associated kinase activities noted as early as 2 hours after addition of retinoic acid. Furthermore, our results imply that the transient induction of p21Cip1 could also be involved. Thus, retinoic acid induced a rapid, but transient increased binding of p21Cip1 to CDK2. The retinoic acid receptor (RAR) agonist TTNPB mimicked the key events affected by retinoic acid, such as pRB phosphorylation, cyclin E expression, and expression of p21Cip1, whereas the RAR-selective antagonist Ro 41-5253 counteracted the effects of retinoic acid. This implies that retinoic acid mediates its growth-inhibitory effect on B lymphocytes via the nuclear receptors.


1992 ◽  
Vol 36 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Luigi J.C. Jonk ◽  
Marjolijn E.J. de Jonge ◽  
Frank A.E. Kruyt ◽  
Christine L. Mummery ◽  
Paul T. van der Saag ◽  
...  

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