Regulation of the uncoupling protein gene expression

1997 ◽  
Vol 136 (3) ◽  
pp. 251-264 ◽  
Author(s):  
J Enrique Silva ◽  
Rogerio Rabelo

Abstract Uncoupling protein (UCP) is essential to the thermogenic function of brown adipose tissue (BAT). The thermogenic role of this protein is due to its capacity to uncouple oxidative phosphorylation in a regulated manner. The thermogenic potential of BAT is determined by its content of UCP. The gene encoding this protein is under complex regulation. Catecholamines, via cAMP, thyroid hormone and retinoic acid, directly stimulate the gene acting upon an upstream (−2·28/−2·49 kb) enhancer sequence, but cAMP may act upon other sequences of the gene as well. CCAAT enhancer binding proteins and peroxisome proliferation activator receptor (PPAR)γ2 have also been implicated in the regulation of the gene acting on discrete sequences. While the thyroid hormone response and retinoic acid response elements (TRE and RARE) have been well defined, the cAMP response elements (CRE) remain elusive. The two TREs are 27 bp apart between −2·33 kb and −2·39 kb. The synergism between cAMP and thyroid hormone seems to reside in a 39 bp sequence downstream (−2·28/−2·32 kb). The most important CRE, the RARE, a cell-specific enhancer and a putative PPAR element are all concentrated in a 90 bp regulatory element of great complexity (−2·40/−22·49 kb). Other hormones, such as insulin and glucocorticoids, and IGF-I also modulate the expression of the gene but their effects seem to be largely indirect. Understanding the regulation of the UCP gene expression may facilitate the development of interventions in obesity and related disorders. European Journal of Endocrinology 136 251–264

1998 ◽  
Vol 157 (2) ◽  
pp. 237-243 ◽  
Author(s):  
MV Kumar ◽  
PJ Scarpace

All-trans-retinoic acid (RA), one of the active metabolites of vitamin A, can increase the expression of uncoupling protein-1 (UCP1) gene. To determine whether RA stimulates brown adipose tissue (BAT) thermogenesis and modulates leptin gene expression in vivo, 6-month-old, vitamin-A sufficient, F344 x BN rats were administered a single dose of RA (7.5 mg/kg, i.p.) or the beta 3-adrenergic receptor (beta 3AR) specific agonist, CGP 12177 (0.75 mg/kg). Levels of UCP1 mRNA in BAT and leptin mRNA in perirenal white adipose tissue (WAT) were examined 5 h after treatment. mRNA levels of lipoprotein lipase (LPL) were also examined in BAT and perirenal WAT. Administration of CGP 12177 caused the expected increase in UCP1 mRNA levels. RA treatment also significantly increased UCP1 mRNA levels but to a lesser extent than CGP 12177. In contrast, there was no acute effect of RA on whole body oxygen consumption, one measure of BAT thermogenesis. Both CGP 12177 and RA treatment decreased levels of leptin mRNA to a similar extent. RA treatment had no effect on mRNA levels of LPL in BAT or perirenal WAT. There were no changes in total DNA content, total protein content, or in the levels of beta-actin mRNA in either BAT or perirenal WAT upon administration of RA or CGP 12177. Thus, the acute effects of RA paralleled the effects of the beta 3AR specific agonist, CGP 12177, on UCP1 and leptin gene expression. This involvement of RA in positive regulation of UCP1 mRNA and negative regulation of leptin mRNA suggests a contrasting role for RA in energy homeostasis.


1997 ◽  
Vol 272 (6) ◽  
pp. E1031-E1036 ◽  
Author(s):  
H. Li ◽  
M. Matheny ◽  
P. J. Scarpace

To investigate the role of beta 3-adrenergic receptors in the suppression of leptin gene expression, we fasted F-344 rats to decrease leptin mRNA levels, refed the rats to stimulate leptin mRNA production, and examined the ability of the beta 3-adrenergic agonist CGP-12177 to prevent the rise in leptin mRNA levels. In the initial 2 h after CGP-12177 (0.75 mg/kg), there were significant reductions in both food consumption and leptin mRNA levels in epididymal, perirenal, and interscapular white adipose tissue. We were unable to detect leptin mRNA in interscapular brown adipose tissue (IBAT), whereas there was a significant increase in uncoupling protein mRNA levels in IBAT after CGP-12177. The suppression of leptin mRNA and food intake by CGP-12177 was confirmed in a second experiment using another rat strain, the F-344 x BN. Furthermore, refeeding after a period of fasting increased leptin mRNA, which was prevented by CGP-12177. These data indicate a role for beta 3-adrenergic-mediated regulation of leptin gene expression in nonmutant rodents and are consistent with other reports suggesting that beta 3-adrenergic agonists suppress food intake.


Endocrinology ◽  
2014 ◽  
Vol 155 (9) ◽  
pp. 3484-3492 ◽  
Author(s):  
Keita Kinoshita ◽  
Nobuaki Ozaki ◽  
Yusuke Takagi ◽  
Yoshiharu Murata ◽  
Yoshiharu Oshida ◽  
...  

Abstract Glucagon, a counterregulatory hormone to insulin, serves as a regulator of glucose homeostasis and acts in response to hypoglycemia. Earlier studies have shown that glucagon administration induces thermogenesis in experimental animal models. However, it is not known whether endogenous glucagon is involved in the regulation of brown adipose tissue (BAT) function. Here we investigated the role of glucagon in cold-induced thermogenesis in male mice deficient in proglucagon-derived peptides (GCGKO mice). Upon exposure to cold, GCGKO mice exhibited a greater decrease in rectal temperature than control mice. The cold exposure-induced increase in oxygen consumption in GCGKO mice was less than that seen in control mice. Moreover, the increase in oxygen consumption after administration of a β3-adrenergic receptor agonist, CL-316,243, was also lesser in GCGKO than in control mice. Expression of thermogenic genes, including the gene encoding uncoupling protein 1 (Ucp1), was reduced in the BAT of GCGKO mice under ambient as well as cold conditions. Administration of glucagon restored the expression of Ucp1 mRNA in the BAT as well as the expression of the fibroblast growth factor 21 gene (Fgf21) in the liver. Supplementation with glucagon for 2 weeks resulted in higher plasma Fgf21 levels and improved responses to CL-316,243 in GCGKO mice. These results indicated that endogenous glucagon is essential for adaptive thermogenesis and that it regulates BAT function, most likely by increasing hepatic Fgf21 production.


1992 ◽  
Vol 12 (9) ◽  
pp. 4153-4163 ◽  
Author(s):  
A J Cooney ◽  
S Y Tsai ◽  
B W O'Malley ◽  
M J Tsai

Alignment of natural chicken ovalbumin upstream promoter transcription factor (COUP-TF) response elements shows that, in addition to the predominant direct repeat of the GGTCA motif with a 2-bp spacing, there are other functional COUP elements with variations in the GGTCA orientation and spacing. We systematically analyzed the binding of in vitro-synthesized COUP-TFs and showed that COUP-TF is capable of binding to oligonucleotides containing both direct repeats and palindromes and with different spacings of the GGTCA repeats. Subsequently, we analyzed four possible mechanisms proposed to explain how COUP-TF could bind to these spatial variations of the GGTCA repeat. We demonstrated that the functional DNA-binding form of COUP-TF is a dimer which requires two GGTCA half-sites to bind DNA. We demonstrated that the COUP-TF dimer undergoes a remarkable structural adaptation to accommodate binding to these spatial variants of the GGTCA repeats. A functional consequence of the promiscuous DNA binding of COUP-TF is its ability to down-regulate hormonal induction of target gene expression by other members of the steroid-thyroid hormone receptor superfamily such as the vitamin D3, thyroid hormone, and retinoic acid receptors. Our data indicate that COUP-TF may have an important role in hormonal regulation of gene expression by these receptors.


1992 ◽  
Vol 12 (9) ◽  
pp. 4153-4163
Author(s):  
A J Cooney ◽  
S Y Tsai ◽  
B W O'Malley ◽  
M J Tsai

Alignment of natural chicken ovalbumin upstream promoter transcription factor (COUP-TF) response elements shows that, in addition to the predominant direct repeat of the GGTCA motif with a 2-bp spacing, there are other functional COUP elements with variations in the GGTCA orientation and spacing. We systematically analyzed the binding of in vitro-synthesized COUP-TFs and showed that COUP-TF is capable of binding to oligonucleotides containing both direct repeats and palindromes and with different spacings of the GGTCA repeats. Subsequently, we analyzed four possible mechanisms proposed to explain how COUP-TF could bind to these spatial variations of the GGTCA repeat. We demonstrated that the functional DNA-binding form of COUP-TF is a dimer which requires two GGTCA half-sites to bind DNA. We demonstrated that the COUP-TF dimer undergoes a remarkable structural adaptation to accommodate binding to these spatial variants of the GGTCA repeats. A functional consequence of the promiscuous DNA binding of COUP-TF is its ability to down-regulate hormonal induction of target gene expression by other members of the steroid-thyroid hormone receptor superfamily such as the vitamin D3, thyroid hormone, and retinoic acid receptors. Our data indicate that COUP-TF may have an important role in hormonal regulation of gene expression by these receptors.


1993 ◽  
Vol 13 (9) ◽  
pp. 5725-5737
Author(s):  
M Au-Fliegner ◽  
E Helmer ◽  
J Casanova ◽  
B M Raaka ◽  
H H Samuels

The receptors for thyroid hormone (T3R), all-trans-retinoic acid (RAR), and 9-cis-retinoic acid (RXR) bind DNA response elements as homo- and heterodimers. The ligand-binding domains of these receptors contain nine conserved heptads proposed to play a role in dimerization. Mutant receptors with changes in the first or last hydrophobic amino acids in the highly conserved ninth heptad of chick T3R alpha [cT3R alpha(L365R) and cT3R(L372R)] and human RAR alpha (hRAR alpha) [hRAR(M377R) and hRAR(L384R)] reveal that this heptad is essential for certain heterodimeric interactions and for diverse functional activities. Without ligands, wild-type receptors form both homodimers and heterodimers, while these mutants form only homodimers. Surprisingly, the cognate ligand for each mutant enables heterodimer formation between cT3R(L365R) and RAR or RXR and between hRAR(M377R) and T3R or RXR. Both cT3R(L365R) and hRAR(M377R) mediate ligand-dependent transcriptional regulation. However, unlike the wild-type receptor, non-ligand-associated cT3R(L365R) does not suppress the basal activity of certain promoters containing thyroid hormone response elements, suggesting that this silencing effect of T3R is mediated by unliganded heterodimers of T3R and endogenous RXR or related factors. Heterodimerization is also necessary for the strong ligand-independent inhibition between T3R and RAR on a common response element, since the ninth-heptad mutants function as poor inhibitors. However, with a T3R-specific response element, hRAR(M377R) acts as a retinoic acid-dependent inhibitor of cT3R, indicating the importance of heterodimerization for this inhibition. Our studies also suggest that the ninth heptad is necessary for the dominant inhibition of wild-type T3Rs by mutant T3Rs, as has been found for the thyroid hormone-resistant syndrome in humans. Thus, the ninth heptad repeat is required for heterodimerization, suppression of basal promoter activity, and dominant negative effects of T3R and RAR. Lastly, the finding that cT3R(L365R) and hRAR(M377R) require ligands for heterodimer formation also raises the possibility that heterodimeric interactions are mediated by the ninth heptad without ligands but by a second region of these receptors with ligands.


Cancers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 397 ◽  
Author(s):  
Krysta Coyle ◽  
Cheryl Dean ◽  
Margaret Thomas ◽  
Dejan Vidovic ◽  
Carman Giacomantonio ◽  
...  

All-trans retinoic acid (atRA) regulates gene expression and is used to treat acute promyelocytic leukemia. Attempts to use atRA in breast cancer without a stratification strategy have resulted in limited overall effectiveness. To identify biomarkers for the treatment of triple-negative breast cancer (TNBC) with atRA, we characterized the effects of atRA on the tumor growth of 13 TNBC cell lines. This resulted in a range of effects that was not predictable based on previously hypothesized predictors of response, such as the levels of atRA nuclear shuttling proteins fatty acid binding protein 5 (FABP5) and cellular retinoic acid binding protein 2 (CRABP2). Transcriptional profiling revealed that atRA induced distinct gene expression changes in the sensitive versus resistant cell lines that were mostly independent of the presence of retinoic acid response elements (RAREs) or peroxisome proliferator response elements (PPREs). Given the importance of DNA methylation in regulating gene expression, we hypothesized that differential DNA methylation could predict the response of TNBCs to atRA. We identified over 1400 sites that were differentially methylated between atRA resistant and sensitive cell lines. These CpG sites predicted the response of four TNBC patient-derived xenografts to atRA, and we utilized these xenografts to refine the profile and identified that as many as 17% of TNBC patients could benefit from atRA treatment. These data illustrate that differential methylation of specific CpGs may be useful biomarkers for predicting the response of patient tumors to atRA treatment.


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