• 생명과학회지
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• 제33권11호
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• pp.859-867
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• 2023

루페올은 5환성 트리테르펜의 일종으로 많은 질병에 치료 효과가 있는 것으로 보고되었으나, 인슐린 저항성에 미치는 영향은 명확하지 않다. 본 연구에서는 3T3-L1 지방세포에서 루페올의 IRS-1 인산화 억제능을 통해 인슐린 저항성 개선효과를 조사하였다. 3T3-L1 세포를 배양하고 TNF-α를 24시간 동안 처리하여 인슐린 저항성을 유도하였다. 서로 다른 농도의 루페올(15, 30 μM) 또는 100 nM의 rosiglitazone을 처리한 세포를 배양한 후, 용해된 세포를 이용하여 western blotting을 시행하였다. 실험결과 루페올은 지방세포에서 TNF-α에 의해 유발되는 인슐린 신호전달의 음성 조절자와 염증 활성화 단백질 kinase에 대한 개선 효과를 나타냈다. 인슐린 신호전달의 음성 조절자인 PTP-1B와 JNK의 활성 및 IKK와 염증활성화 단백질키나아제의 활성을 억제하였다. 또한, 루페올은 IRS-1의 serine 인산화는 하향 조절하고 tyrosine 인산화는 상향 조절하였다. 그 후, 하향 조절된 PI3K/AKT 경로가 활성화되고, GLUT 4의 세포막 전위가 자극되어, 결과적으로 인슐린 저항성이 유도된 3T3-L1 지방세포에서에서 세포내 포도당 흡수가 증가하였다. 본 연구결과, 루페올은 3T3-L1 지방세포에서 인슐린 신호전달 및 염증 활성화 단백질 kinsase들의 음성 조절인자를 억제하여, IRS-1의 serine 인산화를 하향 조절함으로써 TNF-α 유발 인슐린 저항성을 개선할 수 있을 것으로 사료된다.

• Nutrition Research and Practice
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• 제18권1호
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• pp.1-18
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• 2024

BACKGROUND/OBJECTIVES: Endoplasmic reticulum (ER) stress in adipose tissue causes an inflammatory response and leads to metabolic diseases. However, the association between vitamin D and adipose ER stress remains poorly understood. In this study, we investigated whether 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) alleviates ER stress in adipocytes. MATERIALS/METHODS: 3T3-L1 cells were treated with different concentrations (i.e., 10-100 nM) of 1,25(OH)₂D₃ after or during differentiation (i.e., on day 0-7, 3-7, or 7). They were then incubated with thapsigargin (TG, 500 nM) for an additional 24 h to induce ER stress. Next, we measured the mRNA and protein levels of genes involved in unfold protein response (UPR) and adipogenesis using real-time polymerase chain reaction and western blotting and quantified the secreted protein levels of pro-inflammatory cytokines. Finally, the mRNA levels of UPR pathway genes were measured in adipocytes transfected with siRNA-targeting Vdr. RESULTS: Treatment with 1,25(OH)₂D₃ during various stages of adipocyte differentiation significantly inhibited ER stress induced by TG. In fully differentiated 3T3-L1 adipocytes, 1,25(OH)₂D₃ treatment suppressed mRNA levels of Ddit3, sXbp1, and Atf4 and decreased the secretion of monocyte chemoattractant protein-1, interleukin-6, and tumor necrosis factor-α. However, downregulation of the mRNA levels of Ddit3, sXbp1, and Atf4 following 1,25(OH)₂D₃ administration was not observed in Vdr-knockdown adipocytes. In addition, exposure of 3T3-L1 preadipocytes to 1,25(OH)₂D₃ inhibited transcription of Ddit3, sXbp1, Atf4, Bip, and Atf6 and reduced the p-alpha subunit of translation initiation factor 2 (eIF2α)/eIF2α and p-protein kinase RNA-like ER kinase (PERK)/PERK protein ratios. Furthermore, 1,25(OH)₂D₃ treatment before adipocyte differentiation reduced adipogenesis and the mRNA levels of adipogenic genes. CONCLUSIONS: Our data suggest that 1,25(OH)₂D₃ prevents TG-induced ER stress and inflammatory responses in mature adipocytes by downregulating UPR signaling via binding with Vdr. In addition, the inhibition of adipogenesis by vitamin D may contribute to the reduction of ER stress in adipocytes.

• Journal of Ginseng Research
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• 제35권1호
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• pp.45-51
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• 2011

Wild ginseng has been used as a traditional medicine for thousands of years and for increase physical strength in Korea, China and Japan. This study reports that cultivated wild ginseng (CWG) inhibits adipocyte differentiation of 3T3-L1 pre-adipocytes in a concentration-dependent manner. Inhibition of adipocyte differentiation is one possible anti-obesity strategy. CWG inhibits the expression of the adipocyte differentiation regulator peroxisome proliferators-activated receptor (PPAR)${\gamma}$ and CCAAT/enhancer-binding protein ${\alpha}$mRNA. It also inhibited the expression of PPAR${\gamma}$ and adiponectin at the protein level during the differentiation of pre-adipocytes into adipocytes. Additionally, CWG blocked the cell cycle at the sub-$G_1$ phase transition, causing cells to remain in the pre-adipocyte state. These results indicate that CWG inhibits adipocyte differentiation and adipogenesis through pre-adipocyte cell cycle arrest in cultured 3T3-L1 cells.

• 대한본초학회지
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• 제29권2호
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• pp.15-21
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• 2014

Objectives : The purpose of this study was to investigate inhibitory effects of steamed Polygonatum odoratum extract (POE) on differentiation and adipogenesis in 3T3-L1 adipocytes. Methods : Polygonatum odoratum (P. odoratum) extract was extracted with ethyl acetate. Total phenolic and flavonoid contents in POE were measured for antioxidant activity. The spectrophotometric method was used to determine the DPPH and ABTS radical scavenging activity and ferric-reducing antioxidant potential (FRAP). MTT assay was examined for cell toxicity, oil red O staining was performed for intracelluar adipogenesis in differentiated 3T3-L1 adipocytes. Western blot analysis for measurement of CCAAT/enhancer-binding protein ${\alpha}$ ($C/EBP{\alpha}$), peroxisome proliferator-activated receptor${\gamma}$ ($PPAR{\gamma}$) and AMP-activated protein kinase (AMPK) expressions were performed. Results : The results revealed that POE has antioxidant activities. Contents of total polyphenolics and flavonoids were $50.83{\pm}1.52$ GAE mg/100g dry weight of POE and $17.05{\pm}2.47$ RE mg/100g dry weight of POE, respectively. DPPH radical scavenging activity, and FRAP in 10 mg/ml concentration were $92.1{\pm}0.6%$, $244.8{\pm}9.0{\mu}M$ Fe(II) and ABTS inhibition in 5 mg/ml concentration was $84.8{\pm}4.1%$. Treatment of POE in adipocytes inhibited the differentiation and adipogenesis of 3T3-L1 adipocytes compared to those of vehicle control. Additionally, protein expressions of $C/EBP{\alpha}$ and $PPAR{\gamma}$, major transcription factor for the adipogenic genes, were significantly decreased compared to those of vehicle control (p<0.05). Futhermore, phosphorylation of AMPK was increased in 3T3-L1 adipocytes treated with POE compared to that of vehicle control (p<0.05). Conclusions : we demonstrate that steamed P. odoratum extract (POE) has potentiating antioxidant activities, inhibits differentiation and lipid accumulation and also induces energy expenditure in adipocytes, which may contribute to antiobesity property.

• Journal of Applied Biological Chemistry
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• 제62권4호
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• pp.417-424
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• 2019

이 연구의 목적은 당 대사에 대한 삼색싸리(Lespedeza maximowiczii var. tricolor Nakai; LMTN)의 효과를 조사하는 것이다. LMTN 추출물은 대조군과 비교하여 3T3-L1 지방 세포에서 당 섭취능 및 지질축적을 유의하게 향상시켰다. 또한, 3T3-L1 지방 세포에서 LMTN 추출물은 퍼옥시좀 증식제 활성화 수용체(PPAR)γ, 인슐린수용체기질-1 (IRS-1) 및 포도당수송체(GLUT)4의 단백질 발현을 유의하게 증가시켰다. LMTM 추출물의 당 섭취능 또는 인슐린 신호 전달계의 조절 효과는 양성 대조물질인 트로글리타존 또는 피니톨보다 낮았지만 PPARγ 단백 활성화는 증가하였다. 또한, LMTM 추출물은 인슐린 유사효과를 나타냈다. db/db 마우스에서, LMTN 추출물(250 mg/kg BW)은 물과 식이 섭취량, 혈당, 중성지방과 총 콜레스테롤 함량을 유의적으로 감소시켰다. 더불어 지방과 근육조직에서의 PPARγ 및 GLUT4 mRNA의 발현도 LMTN 추출물 투여군에서 유의적으로 증가되었다. 따라서, 본 연구의 결과는 LMTN 추출물이 3T3-L1 지방세포 및 db/db 마우스에서 PPARγ 및 인슐린 유사효과를 통해 당 대사를 조절하는 것으로 밝혀졌다.

• 동의생리병리학회지
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• 제28권5호
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• pp.486-493
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• 2014

Adipocytes are endocrine cells that release bioactive mediators called adipokines. In condition of obesity characterized by low-grade chronic inflammation, adipocytes release inflammatory adipokines, which is related to insulin resistance. Bojungchiseub-tang (BJCST) has been used in symptoms and signs of edema, dampness-phlegm, kidney failure, and so on in Korean medicine. BJCST is also expected to have anti-obesity activities. In the present study, we examined whether BJCST modulate the production of inflammatory adipokines and the activations of the mitogen-activated protein kinases (MAPK) signaling pathway related to induce adipocyte inflammation to elucidate the effects and its mechanism of BJCST on lowering the content of inflammatory adipokines in 3T3-L1 adipocytes. As a result, BJCST suppressed the production of proinflammatory cytokines, tumor necrosis factor (TNF) $-{\alpha}$, interleukin (IL) $-1{\beta}$, IL-6, interferon (IFN) -${\gamma}$, granulocyte-macrophage colony-stimulating factor (GM-CSF), monocyte chemoattractant protein-1 (MCP-1), and the production of other inflammatory mediators, prostaglandin $E_2(PGE_2)$ and nitric oxide(NO)viadownregulationofcyclooxygenase-2(COX-2)andinducible NO synthase (iNOS) gene expressions. In addition, BJCST decreased the phosphorylation of MAPK that promotes the production of inflammatory adipokines in 3T3-L1 mature adipocytes. In conclusion, BJCST could regulate the production of inflammatory adipokines and MAPK signaling pathway related to induction of adipose inflammation.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1500-1504
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• 2009

Effects of methanol extract from turmeric (Curcuma longa L.) (CME) on underlying mechanisms of lipolysis were investigated in 3T3-L1 adipocytes. Compared to the control, lipid accumulation with 72 hr treatment of CME at the concentration $20\;{\mu}g/mL$ was significantly decreased by 19.9% as quantified by Oil red O dye. Intracellular triglyceride (TG) content was also lowered by 19.3%. To determine the mechanism for TG content reduction, glycerol release level was measured. Incubation of 3T3-L1 adipocytes with 15 and $20\;{\mu}g/mL$ of CME significantly elevated the level of free glycerol released into the cultured medium by 20.4 and 28.6%, respectively. In subsequent measurements using quantitative real-time polymerase chain reaction (PCR), mRNA levels of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) were significantly increased by 21.2 and 24.9%, respectively, at the concentration $20\;{\mu}g/mL$. Results indicated that CME stimulated lipolysis through induction of HSL and ATGL mRNA expressions, resulting in increased glycerol release.

• Nutrition Research and Practice
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• 제15권4호
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• pp.444-455
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• 2021

BACKGROUND/OBJECTIVES: Adipocytes undergo angiogenesis to receive nutrients and oxygen needed for adipocyte' growth and differentiation. No study relating quercetin with angiogenesis in adipocytes exists. Therefore, this study investigated the role of quercetin on adipogenesis in 3T3-L1 cells, acting through matrix metalloproteinases (MMPs). MATERIALS/METHODS: After proliferating preadipocytes into adipocytes, various quercetin concentrations were added to adipocytes, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were performed to evaluate cell proliferation. Glycerol-3-phosphate dehydrogenase (GPDH) activity was investigated as an indicator of fat accumulation. The mRNA expressions of transcription factors related to adipocyte differentiation, CCAAT/enhancer-binding proteins (C/EBPs), peroxisomal proliferatoractivated receptors (PPAR)-γ, and adipocyte protein 2 (aP2), were investigated. The mRNA expressions of proteins related to angiogenesis, vascular endothelial growth factor (VEGF)-α, vascular endothelial growth factor receptor (VEGFR)-2, MMP-2, and MMP-9, were investigated. Enzyme activities and concentrations of MMP-2 and MMP-9 were also measured. RESULTS: Quercetin treatment suppressed fat accumulation and the expressions of adipocyte differentiation-related genes (C/EBPα, C/EBPβ, PPAR-γ, and aP2) in a concentration-dependent manner in 3T3-L1 cells. Quercetin treatments reduced the mRNA expressions of VEGF-α, VEGFR-2, MMP-2, and MMP-9 in 3T3-L1 cells. The activities and concentrations of MMP-2 and MMP-9 were also decreased significantly as the concentration of quercetin increased. CONCLUSIONS: The results confirm that quercetin inhibits adipose tissue differentiation and fat accumulation in 3T3-L1 cells, which could occur through inhibition of the angiogenesis process related to MMPs.

• 생명과학회지
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• 제31권8호
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• pp.729-735
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• 2021

제 2 형 당뇨병은 조직의 포도당 흡수 능력에 이상이 있을 때 발생하며, 인슐린에 의한 포도당 섭취와 신진대사는 혈당을 유지하는 기본 활동이며 포도당 섭취는 인슐린이 세포 표면의 수용체에 결합하여 시작되는 다양한 신호 단계를 거친다. 본 연구는 Ecklonia cava에서 분리된 활성 화합물 인 2,7-phloroglucinol-6,6-bieckol이 3T3-L1 지방 세포에서 인슐린 신호전달체계에 따른 포도당 흡수 증가에 미치는 영향에 대한 것이다. 2,7-phloroglucinol-6,6-bieckol 은 3T3-L1 지방 세포에서 농도의존적으로 GLUT4의 발현을 증가시켜 원형질막에서의 glucose uptake 를 증가시켰다. 이는 인슐린 신호 전달 경로에서 2,7-phloroglucinol-6,6-bieckol 에 의한 IRS-1, AKT의 인산화 및 PI3K 활성화에 의한 것이다. PHB는 또한 AMPK 인산화와 활성화를 자극했다. 2,7-phloroglucinol-6,6-bieckol에 의한 PI3K/AKT 및 AMPK 경로의 인산화 및 활성화는 wortmannin (PI3K 억제제) 및 화합물 C (AMPK 억제제)를 사용하여 확인하였다. 본 연구에서 2,7-phloroglucinol-6,6-bieckol 이 3T3-L1 지방 세포에서 PI3K 및 AMPK 경로를 통해 원형질막으로의 GLUT4 전위를 촉진함으로써 포도당 흡수를 증가시킬 수 있음을 나타내었다. 이러한 결과는 2,7-phloroglucinol-6,6-bieckol 가 인슐린 감수성을 개선하는 데 도움이 될 수 있음을 시사한다.

• 동의생리병리학회지
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• 제23권6호
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• pp.1409-1415
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• 2009

Obesity is especially a serious health problem in industrialized countries, because it is considered to be a risk factor associated with the genesis or development of various metabolic diseases, including cardiovascular disease and type 2 diabetes mellitus. The purpose of this study was to investigate the effects of tanshinone IIA from Salvia miltiorrhiza Bunge on induction of apoptossis and inhibition of adipogenesis in in 3T3-L1 preadipocytes and adipocytes. The results demonstrated that tanshinone IIA decreased cell population growth of 3T3-L1 preadipocytes, assessed with the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and LDH (lactate dehydrogenase) assay. Flow cytometric analysis of 3T3-L1 preadipocytes exposed to tanshinone IIA showed that apoptotic cells increased in a timeand dose-dependent manner. Treatment with tanshinone IIA decreased the number of normal cells and increased the number of apoptotic cells in a dose-dependent manner. The induction of apoptosis in 3T3-L1 preadipocytes by tanshinone IIA was mediated through the activation of caspase-3 and Bax, and then through the cleavage of PARP and the down-regulation of Bcl-2. Moreover, tanshinone IIA significantly decreased the amount of intracellular triglycerides and GPDH (glycerol-3-phosphate dehydrogenase) activity in 3T3-L1 adipocytes. Our results suggest that tanshinone IIA efficiently induces apoptosis and inhibits adipogenesis in 3T3-L1 preadipocytes and adipocytes.