• Journal of Life Science
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• v.21 no.2
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• pp.202-210
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• 2011

Adipocyte differentiation is an ordered multistep process requiring the sequential activation of several groups of adipogenic transcription factors, including CCAAT/enhancer-binding protein-$\alpha$ and peroxisome proliferator-activated receptor-$\gamma$, and coactivators. In previous reports, we identified that replication factor C 140 (RFC140) protein played a critical role in regulating adipocyte differentiation as a coactivator. Here, we show expressional regulation of RFC140 and small RFC subunit, RFC38, following characterization of gene promoter of RFC140 and RFC38. In addition, RFC140 increases PPAR$\gamma$-mediated gene activation, resulting from direct protein-protein interaction of RFC140 and PPAR$\gamma$. Taken together, these findings demonstrate that the regulated expression of RFC140 and RFC38 by specific adipocyte transcription factors is required for the adipocyte differentiation process.

• Nutrition Research and Practice
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• v.15 no.5
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• pp.568-578
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• 2021

BACKGROUND/OBJECTIVES: Psidium guajava L. (guava) leaves have been shown to exhibit hypoglycemic and antidiabetic effects in rodents. This study investigated the effects of guava leaf extract on adipogenesis, glucose uptake, and lipolysis of adipocytes to examine whether the antidiabetic properties are mediated through direct effects on adipocytes. MATERIALS/METHODS: 3T3-L1 cells were treated with 25, 50, 100 ㎍/mL of methanol extract from guava leaf extract (GLE) or 0.1% dimethyl sulfoxide as a control. Lipid accumulation was evaluated with Oil Red O Staining and AdipoRed assay. Immunoblotting was performed to measure the expression of adipogenic transcription factors, fatty acid synthase (FAS), and AMP-activated protein kinase (AMPK). Glucose uptake under basal or insulin-stimulated condition was measured using a glucose analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose. Lipolysis from fully differentiated adipocytes was measured by free fatty acids release into the culture medium in the presence or absence of epinephrine. RESULTS: Oil Red O staining and AdipoRed assay have shown that GLE treatment reduced lipid accumulation during adipocyte differentiation. Mitotic clonal expansion, an early essential event for adipocyte differentiation, was inhibited by GLE treatment. GLE inhibited the expression of transcription factors involved in adipocyte differentiation, such as peroxisome proliferator-activated receptor 𝛄 (PPAR𝛄), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein-1c (SREBP-1c). FAS expression was also decreased while the phosphorylation of AMPK was increased by GLE treatment. In addition, GLE increased insulin-induced glucose uptake into adipocytes. In lipid-filled mature adipocytes, GLE enhanced epinephrine-induced lipolysis but reduced basal lipolysis dose-dependently. CONCLUSIONS: The results show that GLE inhibits adipogenesis and improves adipocyte function by reducing basal lipolysis and increasing insulin-stimulated glucose uptake in adipocytes, which can be partly associated with antidiabetic effects of guava leaves.

• Journal of Life Science
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• v.29 no.1
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• pp.60-68
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• 2019

Limonium tetragonum, an edible halophyte that grows on salt marshes in Korea, is thought to possess various health benefits (e.g., antioxidant, antitumor, and hepatoprotective). In the present study, different solvent partitioned subfractions, water ($H_2O$), buthanol (n-BuOH), 85% aqueous methanol (85% aq. MeOH), and hexane (n-hexane), from crude extract of L. tetragonum were tested for their ability to prevent adipogenesis in differentiating 3T3-L1 preadipocytes. The treatment of differentiating 3T3-L1 preadipocytes with L. tetragonum subfractions (LTFs) resulted in suppressed adipogenesis and reduced expression of adipogenesis-related transcription factors such as peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$), CCAATT/enhancer-binding protein alpha ($C/EBP{\alpha}$), and sterol regulatory element-binding protein 1c (SREBP-1c) at both mRNA and protein levels. In addition, the LTF treatment notably decreased the levels of phosphorylated p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) of the mitogen-activated protein kinase (MAPK) pathway in association with $PPAR{\gamma}$-linked adipogenesis. Among all the tested LTFs, $H_2O$ and n-hexane were the most effective in lowering lipid accumulation and regulating the adipocyte differentiation via $PPAR{\gamma}$ pathway. Taken together, the results indicated that the $H_2O$ and n-hexane LTFs contain bioactive compounds that may exhibit significant antiadipogenesis activity by downregulation of the $PPAR{\gamma}$ pathway and inactivation of the MAPK signal pathway in 3T3-L1 preadipocytes.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.21-30
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• 2020

Natural products are widely used due to their various biological activities which include anti-inflammatory, antioxidant, and anti-obesity effects. In this study, we determined the antioxidative and anti-obesity effects of Polygonum cuspidatum 50% ethanol extract (PEE). The antioxidative effect of PEE was evaluated using its radical scavenging activity, total phenolic content, and reducing power. The anti-obesity effect of PEE was investigated using 3T3-L1 adipocytes. The antioxidative activity of PEE was progressively increased in various concentrations, mainly due to the presence of phenolic compounds. PEE also alleviated lipid accumulation on 3T3-L1 adipocytes and downregulated the mRNA and protein production of adipogenesis-related (SREBP-1c, PPARγ, C/EBPα) and lipogenesis-related (aP2, FAS, ACC) markers. Furthermore, we found that the inhibitory effect on lipid accumulation via PEE was caused by the alleviation of NF-κB, p38 MAPK, ERK1/2, and JNK at the protein level. Taken together, our results imply that PEE is a potential antioxidant that can prevent obesity-associated disorders.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.1
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• pp.23-33
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• 2018

Cushing's syndrome (CS) is a collection of symptoms caused by prolonged exposure to excess cortisol. Chronically elevated glucocorticoid (GC) levels contribute to hepatic steatosis. We hypothesized that histone deacetylase inhibitors (HDACi) could attenuate hepatic steatosis through glucocorticoid receptor (GR) acetylation in experimental CS. To induce CS, we administered adrenocorticotropic hormone (ACTH; 40 ng/kg/day) to Sprague-Dawley rats by subcutaneous infusion with osmotic mini-pumps. We administered the HDACi, sodium valproate (VPA; 0.71% w/v), in the drinking water. Treatment with the HDACi decreased steatosis and the expression of lipogenic genes in the livers of CS rats. The enrichment of GR at the promoters of the lipogenic genes, such as acetyl-CoA carboxylase (Acc), fatty acid synthase (Fasn), and sterol regulatory element binding protein 1c (Srebp1c), was markedly decreased by VPA. Pan-HDACi and an HDAC class I-specific inhibitor, but not an HDAC class II a-specific inhibitor, attenuated dexamethasone (DEX)-induced lipogenesis in HepG2 cells. The transcriptional activity of Fasn was decreased by pretreatment with VPA. In addition, pretreatment with VPA decreased DEX-induced binding of GR to the glucocorticoid response element (GRE). Treatment with VPA increased the acetylation of GR in ACTH-infused rats and DEX-induced HepG2 cells. Taken together, these results indicate that HDAC inhibition attenuates hepatic steatosis through GR acetylation in experimental CS.

• Korean Journal of Veterinary Service
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• v.42 no.2
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• pp.43-51
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• 2019

The effects on the radical scavenging activities and hepatic lipid levels in rats fed a high-fat diet (HFD) in the 70% ethanolic extract from Acer tegmentosum Maxim (ATM) were evaluated. Total phenol content of ATM was 168.60 mg catechin/g in the 70% ethanolic extract of Acer tegmentosum. The DPPH and ABTS radical scavenging activities were 18.32 mM TE/g and 32.25 mM TE/g, respectively. Food efficiency ratio was lower significantly in supplemented group with 150 mg/kg BW/day during 5 weeks (HFD+ATM) compared to HFD. Total cholesterol and triglyceride contents in liver tissue of HFD+ATM were lower significantly compared to those of the HFD. Supplementation of ATM significantly decreased lipid peroxide contents and increased radical scavenging activity in the liver tissue compared with that of HFD group. Moreover, the hepatocytes of HFD rats showed a typical fatty liver morphology showing the presence of cytoplasmic lipid droplets, whereas administration of ATM attenuated the number and the size of lipid droplets. In the liver tissue of ATM administrated HFD group, the mRNA levels of SREBP-1c, $PPAR{\gamma}$, and FAS were decreased. Therefore, these results suggest that Acer tegmentosum extracts could have antioxidant activities and the hypolipidemic effects in liver tissue by its phenolic compounds.

• Korean Journal of Food Science and Technology
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• v.53 no.2
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• pp.149-153
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• 2021

Mandarin peel (MP) is a by-product of the processing of citrus juice or other products. This study aimed to investigate the potential anti-obesity effect of an enzymatic extract of MP on the inhibition of adipogenesis in 3T3-L1 adipocytes. The enzymatic extract (MPCE) was prepared using the commercial food-grade carbohydrase Celluclast. Lipid accumulation and triglyceride levels were significantly lower in MPCE-treated cells than in untreated cells. In addition, MPCE treatment reduced the protein expression levels of peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding protein α, sterol regulatory element-binding protein 1, and fatty acid-binding protein 4. These results suggest that MPCE inhibits adipogenesis by downregulating the expression levels of adipogenesis-related proteins. Therefore, the current findings demonstrate that MPCE possesses potent anti-obesity properties and could be a potential ingredient in functional food industries.

• Journal of Marine Bioscience and Biotechnology
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• v.15 no.2
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• pp.59-66
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• 2023

Dictyopteris divaricata, a type of marine brown algae, has been studied for its various biological properties, including anti-inflammatory, antidiabetic, and whitening effects. However, its potential antiobesity effects have not been extensively explored. This study aimed to examine the impact of D. divaricata ethanol extract (DDE) on adipocyte differentiation and adipogenesis using 3T3-L1 preadipocytes. Our results showed that when 3T3-L1 preadipocytes were treated with noncytotoxic concentrations of DDE there was a concentration-dependent decrease in fat accumulation rate and triglycerid production compared with the control. Furthermore, DDE significantly reduced the expression of transcription factors (PPARγ, C/EBPα, and SREBP-1) and fatty acid transport protein (FABP4), which are crucial for 3T3-L1 preadipocyte differentiation. These findings suggest that DDE may exhibit antiobesity effects by suppressing the expression of lipogenic transcription factors and fatty acid transport proteins. Therefore, DDE holds potential as a therapeutic agent for obesity.

• Journal of Korean Medicine for Obesity Research
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• v.23 no.2
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• pp.69-77
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• 2023

Objectives: Atriplex gmelinii C. A. Meyer is a halophyte belonging to the Chenopodiaceae family, and its young leaves and stems are used as fodder for livestock. The aim of the present study was to investigate the effects of A. gmelinii extract and its solvent fractions on lipid accumulation during adipogenesis of 3T3-L1 preadipocytes. Methods: The samples of A. gmelinii were separately extracted using methylene chloride and methanol. Subsequently, they were combined to formulate the initial extract, which was then partitioned based on polarity to prepare solvent fractions. Oil Red O staining was employed to measure lipid accumulation during the differentiation of 3T3-L1 preadipocytes. To verify cytotoxicity in 3T3-L1 cells, MTT assays were conducted. The expression levels of transcription factors in 3T3-L1 preadipocytes were measured through Western blotting analysis. Results: At 50 ㎍/mL, treatment of A. gmelinii extract and its solvent fractions during the differentiation of 3T3-L1 preadipocytes significantly diminished lipid accumulation with no noteworthy cytotoxicity on cell viability. Additionally, when investigating the biochemical pathways that underlie the prevention of lipid accumulation using solvent fractions, it was found that the n-BuOH and n-hexane fractions significantly decreased the expression of key transcription factors involved in the generation of fat, such as peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), and sterol regulatory element-binding protein-1c (SREBP1c). Conclusions: These findings indicate that A. gmelinii can effectively reduce the accumulation of fat in 3T3-L1 adipocytes, making it a potentially valuable material for mitigating and preventing obesity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.10
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• pp.1477-1483
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• 2014

This study investigated the anti-obesity effects of African mango (Irvingia gabonesis, IGOB $131^{TM}$) extract in leptin-deficient obese mice. Experimental groups were treated with two different doses of IGOB $131^{TM}$ (1% and 2% in each AIN93G supplement) for 8 weeks. Treatment of obese mice with both low and high dose of IGOB $131^{TM}$ significantly reduced body weight gain by 10.9% and 13.3%, respectively, compared to control obese mice. Subcutaneous adipose tissue weight of mice was significantly reduced by 18% by low-dose and 23% by high-dose supplementation. This result was supported by micro-CT analysis around the abdominal regions of mice, indicating that the adipose tissue area and volume were significantly reduced by treatment with IGOB $131^{TM}$. Serum levels of triglycerides in the low- and high-dose groups were reduced by 36.5% and 43.8%, respectively, upon treatment with IGOB $131^{TM}$, whereas total cholesterol levels were reduced by 31.8% and 35.4%. Interestingly, the serum LDL level decreased upon treatment with IGOB $131^{TM}$ while the serum level of HDL dramatically increased upon high-dose treatment with IGOB $131^{TM}$, resulting in a significant reduction in the LDL to HDL ratio of 59.2%. These results were supported by the expression levels of enzymes and proteins related to lipid metabolism assessed by real-time PCR. There was a significant increase of in adiponectin expression as well as significant decreases in the expression of FAS, LPL, and lipid regulatory transcription factors such as PPAR-${\gamma}$, C/EBP, and SREBP upon both low- and high-dose IGOB $131^{TM}$ treatment. However, there was no statistical difference between low- and high-dose treatments. These results suggest that IGOB $131^{TM}$ is able to regulate the serum lipid profiles by reducing triglyceride and increasing HDL levels as well as regulate expression of lipid metabolic factors, resulting in reduction of a weight gain in leptin-deficient obese mice.