• 생명과학회지
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• 제19권4호
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• pp.423-428
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• 2009

셀레늄은 필수미네랄로 항산화작용 등의 체내 주요 작용을 수행한다고 알려져 있다. 만성질환 등의 예방과 치료 등의 바람직한 효능을 기대하여 섭취가 늘고 있어서 주목을 받고 있다. 셀레늄은 암의 억제나 혈중포도당조절 및 지방억제 등의 목적으로도 이용되고 있다. 이러한 다양한 연구에도 불구하고 지방세포를 이용한 지방세포분화나 지방세포사멸 촉진에 미치는 영향은 아직 연구되어 있지 않다. 셀레늄의 지방세포조절을 통한 분자기전에 대한 연구는 늘어가고 있는 비만이나 비만관련대사질환의 조절에 학문적 근거를 제공할 수 있다. 본 연구에서는 셀레늄이 AMP-activated protein kinase (AMPK)를 중심으로 지방 미분화세포인 3T3-L1 지방세포의 분화억제 및 분화된 세포의 사멸작용의 기전을 밝히고자 하였다. AMPK는 세포 내 에너지상태의 센서로 작용하는데 실제적으로 운동의 지방대사 촉진기능이 이 단백질에 기인한다는 사실이 밝혀지면서 각광을 받고 있다. 또한 시상하부에서 AMPK는 호르몬이나 영양소 등의 생리적인 인자들을 통합하고 식욕이나 신체에너지 대사를 총괄하는 물질로 대두되고 있다. 셀레늄을 지방세포의 분화과정에 처리하였을 때에 현저한 지방세포로의 분화가 억제되었고 이미 다 분화된 성숙된 지방세포에 처리하였을 때는 세포사멸(apoptosis)을 유도하는 것을 발견하였으며 이와 동시에 AMPK의 활성화 촉진 및 AMPK의 지질인 acetyl-CoA carboxylase의 $serine^{79}$를 인산화하는 것으로 나타났다. 또한 이러한 셀레늄의 지방세포분화 억제 능력은 AMPK의 활성화 합성물질인 AICAR나 포도의 폴리페놀인 레스베라트롤의 능력과 같은 정도의 억제능을 보여주었다. 또한 AMPK의 항 지방축적작용에서의 필수성을 알아보기 위하여 지방세포에 AMPK 활성화 물질인 AICAR와 억제물질인 Compound C를 사용하여 AMPK활성화를 측정하여 본 결과 지방세포분화와 지방축적의 억제과정에 있어서 AMPK가 필수적임을 밝혀내었다.

• Food Science and Biotechnology
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• 제17권5호
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• pp.1047-1051
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• 2008

Overexpression of HER2 in breast cancer cells is considered to induce the expression of acetyl-CoA carboxylase $\alpha$ (ACACA) and fatty acid synthase (FASN) through activation of mammalian target of rapamycin (mTOR) signaling pathway. Resveratrol, a red wine polyphenol, has been shown to induce apoptosis in several cancers by interfering in several signaling pathways. Present study elucidated the mechanism by which resveratrol downregulates ACACA and FASN in breast cancer cells. Resveratrol activated AMP-activated protein kinase (AMPK) and downregulated mTOR in BT-474 cells. These effects of resveratrol were mimicked by AICAR, an AMPK activator, and exogenously expressed constitutively active AMPK, while they were abolished by a dominant-negative mutant of AMPK. The downregulation of mTOR was not accompanied with changes in Akt, the upstream regulator of mTOR. These findings indicate that the downregulation of ACACA and FASN by resveratrol is mediated by the downregulation of mTOR signaling pathway via activation of AMPK.

• 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.

• The Korean Journal of Physiology and Pharmacology
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• 제14권1호
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• pp.1-9
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• 2010

AMP-activated protein kinase (AMPK) protects various tissues and cells from ischemic insults and is activated by many stimuli including mechanical stretch. Therefore, this study investigated if the activation of AMPK is involved in stretch-induced cardioprotection (SIC). Intraventricular balloon and aorto-caval shunt (ACS) were used to stretch rat hearts ex vivo and in vivo, respectively. Stretch preconditioning reduced myocardial infarct induced by ischemia-reperfusion (I/R) and improved post-ischemic functional recovery. Phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase (ACC) were increased by mechanical stretch and ACC phosphorylation was completely blocked by the AMPK inhibitor, Compound C. AMPK activator (AICAR) mimicked SIC. Gadolinium, a blocker of stretch-activated ion channels (SACs), inhibited the stretch-induced phosphorylation of AMPK and ACC, whereas diltiazem, a specific L-type calcium channel blocker, did not affect AMPK activation. Furthermore, SIC was abrogated by Compound C and gadolinium. The in vivo stretch induced by ACS increased AMPK activation and reduced myocardial infarct. These findings indicate that stretch preconditioning can induce the cardioprotection against I/R injury, and activation of AMPK plays an important role in SIC, which might be mediated by SACs.

• The Korean Journal of Physiology and Pharmacology
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• 제16권2호
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• pp.131-138
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• 2012

Alcoholic hepatitis is a leading cause of liver failure in which the increased production of tumor necrosis factor ${\alpha}$ (TNF${\alpha}$) plays a critical role in progression of alcoholic liver disease. In the present study, we investigated the effects of cilostazol, a selective inhibitor of type III phosphodiesterase on ethanol-mediated TNF${\alpha}$ production in vitro and $in$ $vivo$, and the effect of cilostazol was compared with that of pentoxifylline, which is currently used in clinical trial. RAW264.7 murine macrophages were pretreated with ethanol in the presence or absence of cilostazol then, stimulated with lipopolysacchride (LPS). Cilostazol significantly suppressed the level of LPS-stimulated TNF${\alpha}$ mRNA and protein with a similar degree to that by pentoxifylline. Cilostazol increased the basal AMP- activated protein kinase (AMPK) activity as well as normalized the decreased AMPK by LPS. AICAR, an AMPK activator and db-cAMP also significantly decreased TNF${\alpha}$ production in RAW264.7 cells, but cilostazol did not affect the levels of intracellular cAMP and reactive oxygen species (ROS) production. The $in$ $vivo$ effect of cilostazol was examined using ethanol binge drinking (6 g/kg) mice model. TNF${\alpha}$ mRNA and protein decreased in liver from ethanol gavaged mice compared to that from control mice. Pretreatment of mice with cilostazol or pentoxifylline further reduced the TNF${\alpha}$ production in liver. These results demonstrated that cilostazol effectively decrease the ethanol-mediated TNF${\alpha}$ production both in murine macrophage and in liver from binge drinking mice and AMPK may be responsible for the inhibition of TNF${\alpha}$ production by cilostazol.

• BMB Reports
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• 제45권1호
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• pp.32-37
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• 2012

Alternative splicing generates several interleukin-6 (IL-6) isoforms; for them an antagonistic activity to the wild-type IL-6 has been proposed. In this study we quantified the relative abundance of IL-6 mRNA isoforms in a panel of mouse tissues and in C2C12 cells during myoblast differentiation or after treatment with the $Ca^{2+}$ ionophore A23187, the AMP-mimetic AICAR and TNF-${\alpha}$. The two mouse IL-6 isoforms identified, IL-6${\delta}$5 (deletion of the first 58 bp of exon 5) and IL-6${\delta}$3 (lacking exon 3), were not conserved in rat and human, did not exhibit tissue specific regulation, were expressed at low levels and their abundance closely correlated to that of full-length IL-6. Species-specific features of the IL-6 sequence, such as the presence of competitive 3' acceptor site in exon 5 and insertion of retrotransposable elements in intron 3, could explain the production of IL-6${\delta}$5 and IL-6${\delta}$3. Our results argued against biological significance for mouse IL-6 isoforms.

• Tuberculosis and Respiratory Diseases
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• 제78권1호
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• pp.8-17
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• 2015

Background: AMP-activated protein kinase (AMPK) not only functions as an intracellular energy sensor and regulator, but is also a general sensor of oxidative stress. Furthermore, there is recent evidence that it participates in limiting acute inflammatory reactions, apoptosis and cellular senescence. Thus, it may oppose the development of chronic obstructive pulmonary disease. Methods: To investigate the role of AMPK in cigarette smoke-induced lung inflammation and emphysema we first compared cigarette smoking and polyinosinic-polycytidylic acid [poly(I:C)]-induced lung inflammation and emphysema in $AMPK{\alpha}1$-deficient ($AMPK{\alpha}1$-HT) mice and wild-type mice of the same genetic background. We then investigated the role of AMPK in the induction of interleukin-8 (IL-8) by cigarette smoke extract (CSE) in A549 cells. Results: Cigarette smoking and poly(I:C)-induced lung inflammation and emphysema were elevated in $AMPK{\alpha}1$-HT compared to wild-type mice. CSE increased AMPK activation in a CSE concentration- and time-dependent manner. 5-Aminoimidazole-4-carboxamide-1-${\beta}$-4-ribofuranoside (AICAR), an AMPK activator, decreased CSE-induced IL-8 production while Compound C, an AMPK inhibitor, increased it, as did pretreatment with an $AMPK{\alpha}1$-specific small interfering RNA. Conclusion: $AMPK{\alpha}1$-deficient mice have increased susceptibility to lung inflammation and emphysema when exposed to cigarette smoke, and AMPK appears to reduce lung inflammation and emphysema by lowering IL-8 production.

• Molecules and Cells
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• 제45권3호
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• pp.112-121
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• 2022

Calorie restriction (CR) and the activation of autophagy extend healthspan by delaying the onset of age-associated diseases in most living organisms. Because protein kinase CK2 (CK2) downregulation induces cellular senescence and nematode aging, we investigated CK2's role in CR and autophagy. This study indicated that CR upregulated CK2's expression, thereby causing SIRT1 and AMP-activated protein kinase (AMPK) activation. CK2α overexpression, including antisense inhibitors of miR-186, miR-216b, miR-337-3p, and miR-760, stimulated autophagy initiation and nucleation markers (increase in ATG5, ATG7, LC3BII, beclin-1, and Ulk1, and decrease in SQSTM1/p62). The SIRT1 deacetylase, AKT, mammalian target of rapamycin (mTOR), AMPK, and forkhead homeobox type O (FoxO) 3a were involved in CK2-mediated autophagy. The treatment with the AKT inhibitor triciribine, the AMPK activator AICAR, or the SIRT1 activator resveratrol rescued a reduction in the expression of lgg-1 (the Caenorhabditis elegans ortholog of LC3B), bec1 (the C. elegans ortholog of beclin-1), and unc-51 (the C. elegans ortholog of Ulk1), mediated by kin-10 (the C. elegans ortholog of CK2β) knockdown in nematodes. Thus, this study indicated that CK2 acted as a positive regulator in CR and autophagy, thereby suggesting that these four miRs' antisense inhibitors can be used as CR mimetics or autophagy inducers.