• 생명과학회지
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• 제21권5호
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• pp.621-626
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• 2011

AMPK는 catalytic ${\alpha}$ subunit과 regulatory ${\beta}$ 및 ${\gamma}$ subunit으로 구성된 인산화 효소로, 그 동안 생체 내 중요 대사 조절자로써 연구되어 왔으나, 최근 유전학 연구를 통해 지금까지 밝혀지지 아니한 새로운 생체기능을 가짐이 밝혀졌다. 본 연구에서 초파리 유전학 기법을 활용하여 AMPK ${\gamma}$ subunit 유전자가 결손된 모델 초파리를 제작 하여 연구한 결과, AMPK ${\gamma}$ 유전자 결손 시 초파리 embryo의 표피형성이 심각하게 저해됨을 발견하였고, 조직학적 실험을 통해 표피세포의 극성이 AMPK ${\gamma}$ 유전자 결손 초파리에서 손상되어 있음을 확인하였다. 또한 세포극성을 조절하는 중요 분자인 MRLC의 인산화 또한 AMPK ${\gamma}$ 유전자 결손 시 저해되었으며, AMPK ${\gamma}$ 유전자 재도입 시 MRLC인산화와 표피세포의 극성이 모두 회복됨이 확인되어, 초파리 표피세포의 극성유지에 AMPK ${\gamma}$ 유전자가 필수적 임을 확인하였다.

• 한국식품영양학회지
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• 제30권5호
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• pp.1035-1041
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• 2017

(-)-Epigallocatechin-3-gallate (EGCG) is a major catechin found in green tea. It is reported that EGCG possesses various health benefits including anti-cancer, antioxidant, anti-diabetes, and anti-obesity. The objective of this study was to investigate the effects of EGCG on adipogenesis via activation of AMP-activated protein kinase (AMPK) pathway in 3T3-L1 preadipocytes. In order to determine the effects of EGCG on adipogenesis, preadipocyte differentiation was induced in the presence or absence of EGCG ($0{\sim}100{\mu}M$) for a period of 6 days. EGCG significantly inhibited fat accumulation and suppressed the expression of adipogenic specific proteins including peroxisome proliferator-activated receptor (PPAR)-${\gamma}$. Also, EGCG markedly increased the activation of AMPK and acetyl-CoA carboxylase (ACC) and the production of intracellular reactive oxygen species (ROS). However, any pretreatment with a specific AMPK inhibitor, compound C, abolished the inhibitory effects of the EGCG on $PPAR{\gamma}$ expression. This study suggests that EGCG has anti-adipogenic effects through modulation of the AMPK signaling pathway and therefore, may be a promising antiobesity agent.

• KSBB Journal
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• 제25권6호
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• pp.507-512
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• 2010

In this study, we investigated the ability of luteolin, a plant derived flavonoid on hepatocarcinoma cell growth using HepG2 cell culture system. We found that luteolin increased the Smac/DIABLO releases, a mitochondrial protein that potentiates apoptosis. Luteolin also induced either transcriptional activity or expression of PPAR-gamma, a target of cancer growth that PPAR-gamma agonist sensitizes to apoptosis in certain cancer types. To find the possible upstream target molecules of PPAR-gamma activated by luteolin treatment, we used compound C, a specific inhibitor of AMP-activated protein kinase. Pre-treatment of Compound C significantly restored the activation or expression of PPAR-gamma stimulated by luteolin. This result indicated that AMPK signaling might be involved in the activation or expression of PPAR-gamma signaling pathway stimulated by luteolin. Moreover, we also found that luteolin inhibited the insulin-stimulated Akt phosphorylation as well as AICAR, a specific AMPK activator. These results propose that luteolin significantly induces cancer cell death through modulating survival signal pathways such as PPAR-gamma and Akt. AMPK signaling pathway may be an upstream regulator for survival signal pathways such as PPAR-gamma and Akt stimulated by luteolin.

• Asian-Australasian Journal of Animal Sciences
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• 제25권9호
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• pp.1300-1308
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• 2012

The 5'-adenosine monophosphate-activated protein kinase (AMPK) is a key part of a kinase-signaling cascade that acts to maintain energy homeostasis. The objective of this experiment was to investigate the possible effects of fasting and refeeding on the gene expression of hypothalamic AMPK, some appetitive regulating peptides and lipid metabolism related enzymes. Seven-day-old male broiler (Arbor Acres) chicks were allocated into three equal treatments: fed ad libitum (control); fasted for 24 h; fasted for 24 h and then refed for 24 h. Compared with the control, the hypothalamic gene expression of $AMPK{\alpha}2$, $AMPK{\beta}1$, $AMPK{\beta}2$, $AMPK{\gamma}1$, Ste20-related adaptor protein ${\beta}$ ($STRAD{\beta}$), mouse protein $25{\alpha}$ ($MO25{\alpha}$) and agouti-related peptide (AgRP) were increased after fasting for 24 h. No significant difference among treatments was observed in mRNA levels of $AMPK{\alpha}1$, $AMPK{\gamma}2$, LKB1 and neuropeptide Y (NPY). However, the expression of $MO25{\beta}$, pro-opiomelanocortin (POMC), corticotropin-releasing hormone (CRH), ghrelin, fatty acid synthase (FAS), acetyl-CoA carboxylase ${\alpha}$ ($ACC{\alpha}$), carnitine palmitoyltransferase 1 (CPT-1) and sterol regulatory element binding protein-1 (SREBP-1) were significantly decreased. The present results indicated that 24 h fasting altered gene expression of AMPK subunits, appetite regulation peptides and lipometabolism related factors in chick's hypothalamus; the hypothalamic FAS signaling pathway might be involved in the AMPK regulated energy homeostasis and/or appetite regulation in poultry.

• Toxicological Research
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• 제23권2호
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• pp.127-133
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• 2007

Metformin is a drug used to lower blood sugar levels in patients with type 2 diabetes via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). The primary objective of this study was to investigate whether metformin at the pharmacologically effective concentrations affects the expressions of ${\gamma}$-glutamylcysteine synthetase and phase II antioxidant genes in the H4IIE cell. Treatment of the cells with either metformin or 5-aminoimidazole-4-carboxamide riboside (AICAR) abrogated tert-butylhydroxyquinone (t-BHQ) induction of ${\gamma}$-glutamylcysteine synthetase, a rate limiting enzyme of GSH synthesis. The ability of t-BHQ to induce glutathione S-transferases (GSTs), a major class of phase II detoxifying enzymes that playa critical role in protecting cells from oxidative stress or electrophiles, was also inhibited by the agents. Transcriptional gene repression by metformin was verified by the GSTA2 promoter luciferase assay. Moreover, either metformin or AICAR treatment significantly decreased t-BHQ-dependent induction of other GSTs (i.e., $GST{\mu}$ and $GST{\pi}$ forms). Taken together, our data indicate that metformin treatment may result in the repression of ${\gamma}$-glutamylcysteine synthetase and glutathione S-transferase genes possibly via AMPK activation.

• KSBB Journal
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• 제22권5호
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• pp.341-344
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• 2007

진세노사이드 Rd가 지방세포분화에 미치는 영향을 관찰한 결과 다음과 같은 결론을 얻었다. 1. 진세노사이드 Rd는 3T-L1지방세포모델에 있어 효과적으로 지방분화를 억제한다. 2. 진세노사이드 Rd는 세포내 에너지대사의 필수 단백질인 AMPK를 활성화시키고 또한 지방분화과정에 발현 및 활성이 증가하는 PPAR 감마의 활성을 효과적으로 억제한다. 이상의 결과로 진세노사이드 Rd는 세포내 에너지대사를 촉진하여 지방축적 억제에 탁월한 효과를 보일 것으로 사료된다.

• 한방비만학회지
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• 제14권2호
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• pp.55-62
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• 2014

Objective: The prevalence of metabolic syndrome and type 2 diabetes is increasing worldwide. Mitochondrial dysfunction is known to be involved in insulin resistance and obesity, researches have been increasing highly. Astragali Radix extract (ARE) or its main components have been shown to perform comparably to insulin by significantly reducing blood glucose levels in animal models however, the influence on mitochondrial dysfunction are not well understood. Methods: ARE (0.2, 0.5 and 1.0 mg/ml) or metformin (2.5 mM) were treated in C2C12 after 6 day-differentiation. The expressions of adenosine monophosphate (AMP)-activated protein kinase (AMPK) and phosphorylation AMPK, peroxisome proliferators-activated receptror ${\gamma}$ coactivator $1{\alpha}$ ($PGC1{\alpha}$), nuclear respiratory factors 1 (NRF1), mitochondrial transcription factor (Tfam) and myosin heavy chain were detected with western blotting or polymerase chain reaction analysis. The morphological changes were also investigated. Results: ARE dose dependently increased phosphorylation of AMPK and respectively activated mRNA expressions of $PGC1{\alpha}$, NRF1 and Tfam which are mitochondrial biogenesis regulators. Furthermore, there were some morphologic differences of differentiated cells between ARE treatment and control. Conclusions: This study suggests that ARE has the potential to increase muscle mitochondrial function by activating AMPK and $PGC1{\alpha}$.

• KSBB Journal
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• 제27권1호
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• pp.57-60
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• 2012

In this study, we evaluated the effects of Biochanin A on glucose uptake in C2C12 myotube. We found that Biochanin A significantly stimulated 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose (2-NBDG) uptake in a dose-dependent manner. In addition, AMPK and PPAR-gamma activities were markedly increased by Biochanin A in a dose-dependent manner. However, Akt, an insulin dependent signaling molecule, did not change by Biochanin A. These results suggest that Biochanin A stimulates glucose uptake via AMPK and PPAR-gamma pathways.

• 대한본초학회지
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• 제33권3호
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• pp.63-70
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• 2018

Objective : Previous studies showed that water extract of Plantago asiatica (Plantaginis asiaticae Folium, PAF) significantly controlled in body weights, adipose tissue weights and blood lipid profiles in obese C57BL/6 mice. To investigate the mechanism of anti-obesity action of PAF, expressions of obesity-related proteins were identified such as p-AMPK and p-ACC in hypothalamus, UCP-1 in brown adipose tissue, p-AMPK, p-ACC, SREBP-1c, $PPAR{\gamma}$, HMGCR and CPT-1 in liver. Method : Five-weeks old male C57BL/6 mice were divided into 5 groups; ND (normal diet + 0.9% saline), HFD (high-fat diet + 0.9% saline), PC (high-fat diet+Garcinia cambogia 500 mg/kg), PAF 100 and 300 (high-fat diet + PAF 100 or 300 mg/kg). PAF was treated orally for 6 weeks. The protein expression of AMPK, p-AMPK, ACC, p-ACC, $PPAR{\gamma}$, SREBP-1c, HMGCR, CPT-1 and UCP-1 were identified by expression levels of proteins through western blot analysis. Result : The results showed that protein expressions on hypothalamic p-AMPK and p-ACC did not differ between the HFD and PAF groups. In addition, PAF did not affect the increase of UCP-1 in brown adipose tissue. The protein expression levels of hepatic p-AMPK, p-ACC and CPT-1 increased in PAF groups compared to HFD group. And those of $PPAR{\gamma}$, SREBP-1c and HMG-CoA decreased in PAF groups compared to HFD group. Conclusion : These results suggest that the PAF administration induce weight loss via inhibition of lipid metabolism-related protein expressions in hepatic tissues. Therefore, PAF could be used as a potent material of anti-obesity products for prevention and treatment of obesity.

• 한국콘텐츠학회논문지
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• 제9권4호
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• pp.355-363
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• 2009

비정상적인 미토콘드리아에 의해 산화 스트레스가 증가하면 세포내 신호전달 및 유전자 발현에 손상을 일으켜 인슐린 저항성이나 당뇨병 등의 여러 질환들을 유발한다. 그런데 자식작용은 산화 스트레스로 기능이 저하된 미토콘드리아를 제거하여 인슐린 저항성 등을 억제해준다. 한편 운동도 미토콘드리아 생합성을 강화시켜 조직의 기능저하나 퇴행을 회복시켜준다. 따라서 운동과 자식작용이 서로 연관되어 미토콘드리아 생합성을 유도하는 신호체계로 작용할 가능성이 있고, 이 연구를 통해 운동 혹은 AICAR (aminoimidazole-4-carboxamide-1-${\beta}$-D-ribofuranoside)처치로 활성 화된 AMPK(5'-AMP- activated protein kinase) 신호전달체계가 미토콘드리아 생합성을 증가시키는 경로에 자식작용이 관여하는지의 여부를 확인하고자 하였다. 연구결과에 따르면, 6시간의 급성운동으로 쥐의 골격근에서 PGC-1(peroxisome proliferator-activated receptor gamma coactivator 1)과 mtTFA (mitochondrial transcription factor A)의 mRNA 발현이 유의하게 증가하였다. 하지만 자식작용 표지제인 LC3(microtubule-associated proteinl light chain 3)의 mRNA 발현은 증가경향을 나타냈지만 유의하지 않았다. 한편 C2C12 근세포에서도 AICAR 처치에 의해 PGC-1, mtTFA mRNA 발현이 모두 증가하였지만, 이러한 증가는 LC3 SiRNA에 의해서 억제되지 않는 것으로 나타났다. 이러한 결과들을 통해 자식작용은 AMPK에 의해 조절되는 신호전달 전달체계와는 다른 경로로 미토콘드리아 생합성에 영향을 미칠 것으로 사료된다.