• Journal of Ginseng Research
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• 제29권4호
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• pp.159-166
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• 2005

Ginsenosides, a group of Panax ginseng saponins, exert the lowering effects of plasma cholesterol levels in animals. We had reported earlier that ginsenoside Rb2 upregulate low-density lipoprotein receptor (LDLR) expression via a mechanism that is dependent of the activation of sterol response element binding protein 2 (SREBP-2) expression. This study was conducted to determine the effects of ginsenoside Rb2 on the expression of the hepatic LDLR expression at cellular levels using HepG2 cells, and to evaluate whether the sterol response element binding protein 1 (SREBP-l) was involved in the regulation of LDLR expression. Incubation of HepG2 cells in serum-free medium supplemented with cholesterol $(10{\mu}g/ml)$ for 8 hours decreased the mRNAs of LDLR mRNA by $12\%$ and SREBP-l mRNA by $35\%$. Ginsenoside Rb2 antagonized the repressive effects of cholesterol and increased both LDLR and SREBP-l mRNA expression to 1.5- and 2-fold, respectively. Furthermore, Western blot and confocal microscopic analyses with SREBP-l polyclonal antibody revealed that ginsenoside Rb2 enhanced the maturation of the SREBP-1 from the inactive precursor form in ER membrane to the active transcription factor form in nucleus. These results suggest that ginsenoside Rb2 upregulates LDLR expression via a mechanism that is dependent of the activation of not only SREBP-2 expression, but also SREBP-1 expression and maturation, and also indicate that the pharmacological value of ginsenoside Rb2 may be distinguished from that of lovastatin which is reported that it upregulate LDLR through SREBP-2 only, not through SREBP-1.

• 한국발생생물학회지:발생과생식
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• 제26권2호
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• pp.49-58
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• 2022

The differentiation and development of preadipocyte into mature adipocyte are regulated by transcription factors, such as CCAAT enhancer binding protein (Cebp) gene family and sterol regulatory element binding transcription factor 1 (Srebp1). Steroid hormones give influences on the development and function of adipocyte. The present research examined expression patterns of CCAAT enhancer binding protein alpha (Cebpa), CCAAT enhancer binding protein beta (Cebpb), CCAAT enhancer binding protein gamma (Cebpg), sterol regulatory element binding transcription factor 1 (Srebp1), androgen receptor (Ar), and estrogen receptors (Esr) among different epididymal fat parts during postnatal period by quantitative real-time polymerase chain reaction. In the distal epididymal fat, expression of Cebpa, Cebpb, Cebpg, Srebp1, Ar, and Esr2 was increased until 12 months of age, while expression of Esr1 was decreased at 5 months of age and was not detectable after 8 months of age. In the proximal epididymal fat, transcript levels of Cebps and Srebp1 were increased at 8 months of age, followed by decreases of Cebpb and Cebpg transcript levels at 12 months of age. An additional increase of Srebp1 expression was observed at 12 months of age. Expression of Ar and Esr2 were increased until 8 months of age, followed by a drop of Ar expression level at 12 months of age. Expression pattern of Esr1 was similar to that in the distal epididymal fat. In the tail epididymal fat, expression of Cebpa, Cebpg, Srebp1, Ar, and Esr2 was increased with age. Esr1 was not detectable at all. The highest level of Cebpb was observed at 8 months of age. These data suggest the possibility of developmental and functional differentiation among the epididymal fat parts.

• Toxicological Research
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• 제33권3호
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• pp.219-224
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• 2017

Lipin1 was identified as a phosphatidate phosphatase enzyme, and it plays a key role in lipid metabolism. Since free radicals contribute to metabolic diseases in the liver, this study investigated the effects of free radicals on the regulation of Lipin1 expression in Huh7 and AML12 cells. Hydrogen peroxide induced mRNA and protein expression of Lipin1 in Huh7 cells, which was assayed by quantitative RT-PCR and immunoblotting, respectively. Induction of Lipin1 by hydrogen peroxide was confirmed in AML12 cells. Hydrogen peroxide treatment significantly increased expression of sterol regulatory element-binding protein (SREBP)-2, but not SREBP-1. Moreover, nuclear translocation of SREBP-2 was detected after hydrogen peroxide treatment. Hydrogen peroxide-induced Lipin1 or SREBP-2 expression was significantly reduced by N-acetyl-$\small{L}$-cysteine treatment, indicating that reactive oxygen species (ROS) were implicated in Lipin1 expression. Next, we investigated whether the hypoxic environments that cause endogenous ROS production in mitochondria in metabolic diseases affect the expression of Lipin1. Exposure to hypoxia also increased Lipin1 expression. In contrast, pretreatment with antioxidants attenuated hypoxia-induced Lipin1 expression. Collectively, our results show that ROS activate SREBP-2, which induces Lipin1 expression.

• 생명과학회지
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• 제25권3호
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• pp.317-322
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• 2015

알코올에 의한 지방간(지방변성증)은 에탄올 대사에 의해 감소되는 당량의 과도한 발생에 의해 유발된다. 일반적으로 만성적인 에탄올 투여는 간 지질의 합성을 증가시키는 sterol regulatory element-binding protein 1c (SREBP-1c)를 조절함으로써 지방변성증을 유발시킨다. SPEBP-1c에서 에탄올의 영향은 간에서의 지방대사를 조절하는 NAD⁺ 의존적 단백질 탈아세틸화효소인 mammalian sirtuin-1 (SIRT-1)에 의해 조정된다. 홍삼은 항당뇨와 항비만 효과를 위해 아시아에서 광범위하게 사용되는 한약재이다. 홍삼의 약리학적 치료학적인 효과는 진세노사이드와 같은 생물활성 성분에 의해 주로 일어난다. 따라서 우리는 마우스 간세포주인 AML-12 세포에서 SREBP-1과 SIRT-1에대한 한국홍삼 추출물의 조절효과를 평가하였다. 알코올과 홍삼추출물(0-1,000 μg/ml)을 AML-12 세포주에 처리하고, 지방소립을 Oil red O 염색법으로 확인하고, western blots을 사용해 SIRT-1과 SREBP-1의 발현을 확인하였다. 에탄올을 처리한 세포에서 홍삼추출물은 SIRT-1과 SREBP-1c의 발현을 회복시켰다. 또한 에탄올이 처리된 세포에서 홍삼추출물과 진세노사이드 Rb₂와 Rd가 SREBP-1을 유의적으로 감소시키는 것으로 확인 되었다. 결과적으로 홍삼과 활성 진세노사이드 성분인 Rb₂와 Rd가 SIRT-1과 간 지질대사를 변화시키는 SREBP-1c의 아세틸화의 조절을 통해 알코올에 의한 간지방변성을 억제하는 것을 확인하였다.

• 대한한의학방제학회지
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• 제30권3호
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• pp.137-143
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• 2022

Objectives : Brain-Liver axis is an important target of the chronic human diseases. Hepatic steatosis is one of the most famous disorders in the chronic diseases. This study investigated the moderating effect of beneficial herbs on the fat accumulation, which is mediated by the LXR alpha-SREBP-1c signaling pathway. Methods : In order to confirm the SREBP-1c inhibitory effect, we performed immonoblotting ananlysis using HepG2 cells and Huh 7 cells treated by T0901317, the ligand of LXRα. Results : Forsythiae suspensa water extract (FSE) was not cytotoxicity in cell lines. FSE inhibited SREBP-1c protein expression in HepG2 and Huh7 cells induced by T0901317. In addition, FSE increased the phosphorylation of LKB1, which is associated with LXR-related pathway in HepG2 and Huh 7 cells. Conclusions : These results showed that FSE activated LKB1 to suppress SREBP-1c, which protects the cells against oxidative stress.

• BMB Reports
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• 제46권4호
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• pp.207-212
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• 2013

The main purpose of this study is to examine the effect of caffeine on lipid accumulation in human hepatoma HepG2 cells. Significant decreases in the accumulation of hepatic lipids, such as triglyceride (TG), and cholesterol were observed when HepG2 cells were treated with caffeine as indicated. Caffeine decreased the mRNA level of lipogenesis-associated genes (SREBP1c, SREBP2, FAS, SCD1, HMGR and LDLR). In contrast, mRNA level of CD36, which is responsible for lipid uptake and catabolism, was increased. Next, the effect of caffeine on AMP-activated protein kinase (AMPK) signaling pathway was examined. Phosphorylation of AMPK and acetyl-CoA carboxylase were evidently increased when the cells were treated with caffeine as indicated for 24 h. These effects were all reversed in the presence of compound C, an AMPK inhibitor. In summary, these data indicate that caffeine effectively depleted TG and cholesterol levels by inhibition of lipogenesis and stimulation of lipolysis through modulating AMPK-SREBP signaling pathways.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
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• pp.43-43
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• 2023

In this study, we investigated in vitro inhibitory activity of wild-simulated ginseng (WSG) against non-alcoholic fatty liver disease using HepG-2 cells. T0901317 treatment increased the lipid accumulation in HepG-2 cells, but WSG treatment inhibited T0901317-mediated lipid accumulation. In addition, WSG downregulated T0901317-mediated expression of SREBP-1c, ACC, FAS and SCD-1 protein. In addition, WSG increased the phosphorylation level of LKB1 and AMPK. Compound C treatment blocked WSG-mediated downregulation of SREBP-1c protein. In conclusion, WSG is considered to inhibit the accumulation of lipids and triglycerides in HepG-2 cells by inducing the activation of LKB1 and AMPK successively, thereby reducing the expression of FAS, ACC, and SCD-1 through suppression of SREBP-1c expression.

• 한국자원식물학회지
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• 제36권1호
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• pp.26-31
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• 2023

간세포 내 LXRα활성화는 전사조절인자인 SREBP-1c의 발현을 증가시키고, 발현된 SREBP-1c는 핵내로 이동하여 지질형성 관련 유전자인 FAS, ACC, SCD-1 등의 프로모토에 결합하여 FAS, ACC, SCD-1을 유도하여 중성지질의 합성을 활성화시켜 비알코올성 지방간을 초래한다. 그러나 산양삼은 LKB1 그리고 연속적으로 AMPK의 활성화을 유도하여 SREBP-1c의 발현 억제를 통해 FAS, ACC, SCD-1의 발현을 감소시켜 간세포 내 지질 및 중성지질의 축적을 억제하는 것으로 판단된다. 본 결과를 미루어 볼 때, 산양삼은 비알코올성 지방간을 예방하기 위한 건강기능성 식품소재로 개발로 활용될 수 있을 것으로 판단된다.

• BMB Reports
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• 제43권2호
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• pp.140-145
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• 2010

The present study investigated whether the mammalian target of rapamycin (mTOR) signal pathway is involved in the regulation of high glucose-induced intramuscular adipogenesis in porcine muscle satellite cells. High glucose (25 mM) dramatically increased intracellular lipid accumulation in cells during the 10-day adipogenic differentiation period. The expressions of CCAAT/enhancer binding protein-$\alpha$ (C/EBP-$\alpha$) and fatty acid synthase (FAS) protein were gradually enhanced during the 10-day duration while mTOR phosphorylation and sterol-regulatory- element-binding protein (SREBP)-1c protein were induced on day 4. Moreover, inhibition of mTOR activity by rapamycin resulted in a reduction of SREBP-1c protein expression and adipogenesis in cells. Collectively, our findings suggest that the adipogenic differentiation of porcine muscle satellite cells and a succeeding extensive adipogenesis, which is triggered by high glucose, is initiated by the mTOR signal pathway through the activation of SREBP-1c protein. This process is previously uncharacterized and suggests a cellular mechanism may be involved in ectopic lipid deposition in skeletal muscle during type 2 diabetes.

• Natural Product Sciences
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• 제26권3호
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• pp.200-206
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• 2020

The ability of the total extract from Physalis angulata; three fractions after partitioning with n-hexane, ethyl acetate (TBE), and water; and four withanolides (compounds 1 - 4) to phosphorylate 5'-adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells was evaluated. The TBE fraction (50 ㎍/mL) activated p-ACC and p-AMPK expression most strongly. Compounds 1 - 4 (10 μM) upregulated p-ACC expression at different levels. Compound 4 induced the most significant changes in p-AMPK expression, followed by 1 and 2. Sterol regulatory element-binding proteins (SREBPs) play a functional role in the transcriptional regulation of the lipogenic pathway, including fatty acid synthase (FAS) and ACC. The effects of compounds 2 and 4 (10 μM) on FAS and SREBP-1c expression under high glucose conditions (30 mM) in HepG2 cells were evaluated further. Both dose-dependently inhibited FAS and SREBP-1c expression as well as lipid accumulation (1 - 10 μM) were compared to high-concentration glucose control, which upregulated FAS and SREBP-1c. These results suggest that compounds 2 and 4 upregulate AMPK, suppress FAS and SREBP-1c, and have potential effects on glucose and lipid metabolism.