• BMB Reports
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• v.40 no.6
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• pp.921-927
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• 2007

UCP2 and UCP3 are members of the uncoupling protein family, which may play roles in energy homeostasis. In order to determine the regulation of the predominant expression of UCP3 in skeletal muscle, the effects of differentiation and myogenic regulatory factors on the promoter activities of the mouse UCP2 and UCP3 genes were studied. Reporter plasmids, containing approximately 3 kb of the 5'-upstream region of the mouse UCP2 and UCP3 genes, were transfected into C2C12 myoblasts, which were then induced to differentiate. Differentiation positively induced the reporter expression about 20-fold via the UCP3 promoter, but by only 2-fold via the UCP2 promoter. C2C12 myoblasts were cotransfected with expression vectors for myogenin and/or MyoD as well as reporter constructs. The simultaneous expression of myogenin and MyoD caused an additional 20-fold increase in the reporter expression via the UCP3 promoter, but only a weak effect via the UCP2 promoter. In L6 myoblasts, only MyoD activated the UCP3 promoter, but in 3T3-L1 cells neither factor activated the UCP3 promoter, indicating that additional cofactors are required, which are present only in C2C12 myoblasts. The expression of UCP2 and UCP3 is differentially regulated during muscle differentiation due to the different responsiveness of their promoter regions to myogenin and MyoD.

• Journal of Marine Life Science
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• v.8 no.2
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• pp.186-189
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• 2023

Uncoupling protein 1 (UCP1) is a unique mitochondrial membranous protein expressed in brown adipose tissue (BAT) in mammals. While its expression in response to cold temperatures and adipogenic inducers is well-characterized in mammals and human infants, the molecular characterization and expression of UCP1 in fish remain unexplored. To address this gap, we analyzed UCP1 expression in response to adipogenic inducers in a fish cell line, rainbow trout gonadal cells (RTG-2), and compared it with UCP1 expression in three mammalian preadipocytes, 3T3-L1, T37i, and WT1 exposed to the Peroxisome proliferator-activated receptor gamma (PPARγ) agonists, rosiglitazone (Rosi). In mammalian preadipocytes, UCP1 protein was highly expressed by Rosi, with an induction of adipogenesis observed in a time-dependent manner. This suggests that UCP1 plays a significant role in adipogenesis in mammals. However, RTG-2 cells showed no response to adipogenic inducers and exhibited only marginal expressions of UCP1. These results imply that RTG-2 cells may lack crucial responsive mechanisms to adipogenic signals or that the adipogenic response is regulated by other mechanisms. Further studies are needed to confirm these phenomena in fish preadipocytes when an appropriate cell line is established in future research.

• BMB Reports
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• v.54 no.8
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• pp.419-424
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• 2021

Cold-induced norepinephrine activates β3-adrenergic receptors (β3-AR) to stimulate the kinase cascade and cAMP-response element-binding protein, leading to the induction of thermogenic gene expression including uncoupling protein 1 (Ucp1). Here, we showed that stimulation of the β3-AR by its agonists isoproterenol and CL316,243 in adipocytes increased the expression of Ucp1 and Heme Oxygenase 1 (Hmox1), the principal Nrf2 target gene, suggesting the functional interaction of Nrf2 with β3-AR signaling. The activation of Nrf2 by tert-butylhydroquinone and reactive oxygen species (ROS) production by glucose oxidase induced both Ucp1 and Hmox1 expression. The increased expression of Ucp1 and Hmox1 was significantly reduced in the presence of a Nrf2 chemical inhibitor or in Nrf2-deleted (knockout) adipocytes. Furthermore, Nrf2 directly activated the Ucp1 promoter, and this required DNA regions located at -3.7 and -2.0 kb of the transcription start site. The CL316,243-induced Ucp1 expression in adipocytes and oxygen consumption in obese mice were partly compromised in the absence of Nrf2 expression. These data provide additional insight into the role of Nrf2 in β3-AR-mediated Ucp1 expression and energy expenditure, further highlighting the utility of Nrf2-mediated thermogenic stimulation as a therapeutic approach to diet-induced obesity.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.2
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• pp.170-175
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• 2019

Objective: Uncoupling protein 3 gene (UCP3) is a candidate gene associated with the meat quality of pigs. The aim of this study was to explore the regulation mechanism of UCP3 expression and provide a theoretical basis for the research of the function of porcine UCP3 gene in meat quality. Methods: Bisulfite sequencing polymerase chain reaction (PCR) and quantitative real-time PCR (Q-PCR) were used to analyze the methylation of UCP3 5′-flanking region and UCP3 mRNA expression in the adipose tissue or skeletal muscle of three pig breeds at different ages (1, 90, 210-day-old Putian Black pig; 90-day-old Duroc; and 90-day-old Dupu). Results: Results showed that two cytosine-guanine dinucleotide (CpG) islands are present in the promoter region of porcine UCP3 gene. The second CpG island located in the core promoter region contained 9 CpG sites. The methylation level of CpG island 2 was lower in the adipose tissue and skeletal muscle of 90-day-old Putian Black pigs compared with 1-day-old and 210-day-old Putian Black pigs, and the difference also existed in the skeletal muscle among the three 90-day-old pig breeds. Furthermore, the obvious changing difference of UCP3 mRNA expression was observed in the skeletal muscle of different groups. However, the difference of methylation status and expression level of UCP3 gene was not significant in the adipose tissue. Conclusion: Our data indicate that UCP3 mRNA expression level was associated with the methylation status of UCP3 promoter in the skeletal muscle of pigs.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.11
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• pp.1552-1556
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• 2005

The UCPs are members of the mitochondrial inner membrane transporter family, present in the mitochondrial inner membrane. Their main function is increasing the energy expenditure via diminishing the resulting production of ATP from mitochondrial oxidative phosphorylation instead of yielding dissipative heat. They are associated with the metabolism of fat and regulation of energy expenditure. The UCP gene can be viewed as the candidate gene for chicken fatness. In the present study, RT-PCR and Northern Blot methods were developed to investigate the expression of the UCP gene in ten tissues including heart, liver, spleen, lung, kidney, gizzard, intestine, brain, breast muscle and abdominal fat of chicken. The results of both RT-PCR and Northern Blot methods showed that the UCP gene expressed specific in breast muscle. The expression levels of UCP gene in breast muscles from egg-type and meat-type chickens of hatching, 2, 4, 6 and 8 wk of age were detected by RT-PCR assay and results showed that the expression levels of UCP gene were related to breeds. Expression level of UCP gene in layers was higher than that in broilers at various weeks of age except at 6 wk. The UCP gene's expression was higher at 6 wk and had no significant difference among other weeks of age in broilers; in layers the expression level of UCP gene had no significant difference among weeks of age. The experiment results also showed that insulin could increase the expression level of UCP gene by 40% compared with control group.

• Journal of Life Science
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• v.19 no.2
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• pp.213-218
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• 2009

The purpose of this study was to investigate the UCP-1, UCP-3 mRNA expression in brown adipose tissue with glycometabolism according to intensity and duration of swimming in rat. F344 rat were randomly divided into three groups (n=10 in each group): control (CON), low-intensity swimming (LIS) groups, and high-intensity swimming (HIS) groups. Animals in the LIS group were forced to swim in swimming pool for 30min once a day for 8 consecutive weeks with a light intensity. In the HIS group, the rats repeated fifteen 20-s swimming bouts with a weight equivalent to 10% of body weight for 8weeks, respectively. The present result demonstrated that in LIS group, serum insulin and glucose levels significantly decreased in LIS group compared to CON. Brown adipose tissue UCP-1 and UCP-3mRNA expression was significantly increase in LIS group compared to CON and HIS groups. From those results, it can be suggested that low-intensity swimming may improve glycometablism control by up-regulating UCP-1 and UCP-3mRNA expression.

• Journal of Nutrition and Health
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• v.35 no.9
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• pp.903-911
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• 2002

The effects of dietary levan, high-molecular-weight $\beta$-2,6-linked fructose polymer, on adiposity, serum leptin and UCP expression in rats fed high fat diet were studied. The adipose tissue hormone, leptin has been proposed to be involved in the regulation of food intake and energy expenditure. Uncoupling protein (UCP), a mitochondrial protein that uncouples the respiratory chain from oxidative phosphorylation, generates heat instead of ATP, thereby increase energy expenditure. To determine whether the dietary levan may have the anti-obesity effect, 4 wk old Sprague Dawley male rats fed high fat diet for 6 wks to induce obesity, and subsequently fed one of three diets for further 6 wks: 1) high fat (40% of calories) diet without levan 2) with 3% (w/w) levan 3) with 5% levan. For the comparison, control group fed AIN-76A diet. Visceral and peritoneal fat masses were lower in high fat diet with levan groups compared to high fat diet group. The effect of levan was dose-dependent. Adipocyte size was significantly reduced in the levan diet groups compared to the no levan diet group. Serum cholesterol level was not affected by levan containing diet, while the serum HDL cholesterol level was higher in leven diet groups. In addition, serum triglyceride level was markedly reduced by levan containing diet, thus lower than that of control group. Serum leptin was reduced by levan containing diet and lower in 5% levan group compared to 3% levan group (p < 0.001), as a result, serum leptin and insulin levels of 5% levan group were reduced to level of control group. Futhermore, the serum leptin level reflected the adiposity. The expression of UCP 1, and UCP 2 in brown adipose tissue was up-regulated by levan containing diet. In conclusions, levan containing diet reduced adiposity and serum triglyceride but increased UCP expression in the obese rats fed high fat diet. (Korean J Nutrition 35(9) : 903~911, 2002)

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.788-795
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• 2002

This study described the effect of levan (9-2,6-linked fructose polymer) feeding on serum lipids, adiposity and uncoupling protein (UCP) expression in growing rats. Levan was synthesized from sucrose using bacterial levansucrase. UCP is a mitochondrial protein that uncouples the respiratory chain from oxidative Phosphorylation and generates heat instead of ATP, thereby increase energy expenditure. We observed that 3% or 5% levan containing diet reduced serum triglyceride levels, visceral and peritoneal fat mass and induced the UCP expression in rats fed high fat diet in previous study. To determine whether the intake of low level of levan may have the hypolipidemic and anti-obesity effect, 4 wk old Sprague Dawley male rats were fed AIN-76A diet for 6 wk, and sub-sequently fed 1% or 2% levan solution for further 5 wk. Intake of 1% levan in liquid form reduced serum triglyceride and serum total cholesterol levels to 50% and 66% of control group, respectively. Although epididymal and peritoneal fat masses were not affected by levan feeding, visceral fat mass was lower in 1% levan group compared to control group. The expression of UCP2 mRNA in brown adipose tissue, skeletal muscle and hypothalamus and UCP3 mRNA in skeletal muscle were not changed by levan feeding, while the UCP2 mRNA in white adipose tissue was up-regulated by levan feeding. In conclusions, intake of low level of levan solution reduced serum triglyceride and total cholesterol, restrained the visceral fat accumulation and increased UCP expression in white adipose tissue in rats. This study suggests that hypolipidemic and anti-obesity effect of levan attributed to anti-lipogenesis and inefficeint energy utilization by up-regulation of UCPs.

• BMB Reports
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• v.39 no.4
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• pp.346-354
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• 2006

The full-length cDNA of grass carp (Ctenopharyngodon idellus) and silver carp (Hypophthalmichthys molitrix) uncoupling protein 2 (UCP2) was obtained from liver. The grass carp UCP2 cDNA was determined to be 1152 bp in length with an open reading frame that encodes 310 amino acids. Five introns (Intron 3, 4, 5, 6 and 7) in the translated region, and partial sequence of Intron 2 in the untranslated region of grass carp UCP2 gene were also obtained. Gene structure comparison between grass carp and mammalian (human and mouse) UCP2 gene shows that, the UCP2 gene structure of grass carp is much similar to that of human and mouse. Partial UCP2 cDNA sequences of bighead carp (Aristichthys nobilis) and mud carp (Cirrhinus molitorella), were further determined. Together with the common carp (Cyprinus carpio) UCP2 sequence from GenBank (AJ243486), multiple alignment result shows that the nucleotide and amino acid sequences of the UCP2 gene, were highly conserved among the five major Chinese carps that belong to four subfamilies. Using beta-actin as control, the ratio UCP2/beta-actin mRNA (%) was determined to be $149.4{\pm}15.6$ (common carp), $127.4{\pm}22.1$ (mud carp), $96.7{\pm}12.7$ (silver carp), $94.1{\pm}26.8$ (bighead carp) and $63.7{\pm}16.2$ (grass carp). The relative liver UCP2 expression of the five major Chinese carps, shows a close relationship with their food habit: benthos and detrituseating fish (common carp and mud carp) > planktivorious fish (silver carp and bighead carp) > herbivorious fish (grass carp). We suggest that liver UCP2 might be important for Chinese carps to detoxify cyanotoxins and bacteria in debris and plankton food.

• Journal of Life Science
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• v.19 no.1
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• pp.15-20
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• 2009

Uncoupling protein 3 (UCP3) is a mitochondrial protein that is expressed predominantly in skeletal muscle. It may play a role in altering metabolic function. However, its major physiological roles are not fully understood. Recently de novo expression of UCP3 in rat liver by fenofibrate was reported. We also reported previously that fenofibrate-induced de novo expression of UCP3 contributes to reduction of adipose tissue in obese rats. In the present study, we investigated that ienofibrate-induced expression of UCP3 in rat liver is related with metabolic function such as body weight and hepatic lipid content by time-dependent manner in high-fat diet rats. Eight-week-old male Sprague-Dawley rats were randomly divided into two groups; the high fat diet group (HF, n=16) and fenofibrate-treated high fat diet group (HFF, n=16). The mRNA expression of hepatic UCP3 was detected as early as 1 week of fenofibrate treatment by quantitative real-time PCR and the amount of mRNA was increased time-dependently. The mean body weight of the HFF group was significantly less com. pared with the HF group after 6 weeks of fenofibrate treatment, even though there was no difference of food intake between the two groups. Rectal temperature was increased during 4 to 6 weeks of fenofibrate treatment and body weight was decreased after 6 weeks of treatment. These results were corresponded with the increased amount of the expression of UCP3 mRNA and protein. We suggest that de novo expression of hepatic UCP3 is increased time-dependently with fenofibrate treatment and that the amount of expression is correlated with metabolic function.