• Molecules and Cells
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• 제24권2호
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• pp.224-231
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• 2007

$H_2O_2$, as an example of oxidative stress, induces cardiac myocyte apoptosis. Bcl-2 family proteins are key regulators of the apoptotic response while their functions can be regulated by post-translational modifications including phosphorylation, dimerization or proteolytic cleavage. In this study, we examined the role of various protein kinases in regulating total BAD protein levels in adult rat cardiac myocytes undergoing apoptosis. Stimulation with 0.1 mM $H_2O_2$, which induces apoptosis, resulted in a marked down-regulation of BAD protein, which is attributed to cleavage by caspases since it can be restored in the presence of a general caspase inhibitor. Inhibition of PKC, p38-MAPK, ERK1/2 and PI-3-K did not influence the reduced BAD protein levels observed after stimulation with $H_2O_2$. On the contrary, inhibition of PKA or specifically $PKC{\delta}$ resulted in up-regulation of BAD. Decreased caspase 3 activity was observed in $H_2O_2$ treated cells after inhibition of PKA or $PKC{\delta}$ whereas inhibition of PKA also resulted in improved cell survival. Furthermore, addition of okadaic acid to inhibit selected phosphatases resulted in enhanced BAD cleavage. These data suggest that, during oxidative stress-induced cardiac myocyte apoptosis, there is a caspase-dependent down-regulation of BAD protein, which seems to be regulated by coordinated action of PKA, $PKC{\delta}$ and phosphatases.

• The Korean Journal of Physiology and Pharmacology
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• 제19권3호
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• pp.263-268
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• 2015

5-Lipoxygenase (5-LO) plays a pivotal role in the progression of atherosclerosis. Therefore, this study investigated the molecular mechanisms involved in 5-LO expression on monocytes induced by LPS. Stimulation of THP-1 monocytes with LPS ($0{\sim}3{\mu}g/ml$) increased 5-LO promoter activity and 5-LO protein expression in a concentration-dependent manner. LPS-induced 5-LO expression was blocked by pharmacological inhibition of the Akt pathway, but not by inhibitors of MAPK pathways including the ERK, JNK, and p38 MAPK pathways. In line with these results, LPS increased the phosphorylation of Akt, suggesting a role for the Akt pathway in LPS-induced 5-LO expression. In a promoter activity assay conducted to identify transcription factors, both Sp1 and NF-${\kappa}B$ were found to play central roles in 5-LO expression in LPS-treated monocytes. The LPS-enhanced activities of Sp1 and NF-${\kappa}B$ were attenuated by an Akt inhibitor. Moreover, the LPS-enhanced phosphorylation of Akt was significantly attenuated in cells pretreated with an anti-TLR4 antibody. Taken together, 5-LO expression in LPS-stimulated monocytes is regulated at the transcriptional level via TLR4/Akt-mediated activations of Sp1 and NF-${\kappa}B$ pathways in monocytes.

• Journal of Microbiology
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• 제38권4호
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• pp.265-269
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• 2000

Iron increased the susceptibilities of clinical isolates Pseudomonas aeruginosa to quinolones. In the presence of iron, increased susceptibilities to ofloxacin were observed in twenty-six out of thirty isolates and with no change in four isolates. In the case of norfloxacin, iran increased susceptibilities of twelve isolates but did not render any change in eighteen isolates. In the case of ciprofloxacin, iron decreased the MICs (Minimal Inhibitory Concentration) of twenty isolates, increased the MIC of one isolate, and did net change the MICs of nine isolates. To find out how iron increased susceptibility to ofloxacin, bacterial cells were grown in Muller Hinton (MH) media and succinate minimal media (SMM) to induce iran acquisition systems and the intracellular ofloxacin concentrations were assayed in the presence of iron. The addition of iron to the media decreased the MICs of cells whether they were grown in MH or SMM. Siderophores, carbonyl cyanide m-chlorophenylhydrazone (an inhibiter of proton motive force), and ouabain (an inhibitor of ATPase) did not decrease the effect of iron. Results suggested that the increase in the intracellular ofloxacin concentration by iron is accomplished not by decreasing the efflux but by increasing the of ofloxacin permeability.

• Journal of Ginseng Research
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• 제46권3호
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• pp.444-453
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• 2022

Background: Compound K (CK) is among the protopanaxadiol (PPD)-type ginsenoside group, which produces multiple pharmacological effects. Herein, we examined the effects of CK on muscle atrophy under hyperlipidemic conditions along with its pro-myogenic effects. Further, the molecular pathways underlying the effects of CK on skeletal muscle have been justified. Methods: C2C12 myotubes were treated with palmitate and CK. C2C12 myoblasts were differentiated using CK for 4-5 days. For the in vivo experiments, CK was administered to mice fed on a high-fat diet for 8 weeks. The protein expression levels were analyzed using western blotting analysis. Target protein suppression was performed using small interfering (si) RNA transfection. Histological examination was performed using Jenner-Giemsa and H&E staining techniques. Results: CK treatment attenuated ER stress markers, such as eIF2a phosphorylation and CHOP expression and impaired myotube formation in palmitate-treated C2C12 myotubes and skeletal muscle of mice fed on HFD. CK treatment augmented AMPK along with autophagy markers in skeletal muscle cells in vitro and in vivo experiments. AMPK siRNA or 3-MA, an autophagy inhibitor, abrogated the impacts of CK in C2C12 myotubes. CK treatment augmented p38 and Akt phosphorylation, leading to an enhancement of C2C12 myogenesis. However, AMPK siRNA abolished the effects of CK in C2C12 myoblasts. Conclusion: These findings denote that CK prevents lipid-induced skeletal muscle apoptosis via AMPK/autophagy-mediated attenuation of ER stress and induction of myoblast differentiation. Therefore, we may suggest the use of CK as a potential therapeutic approach for treating muscle-wasting conditions associated with obesity.

• 한국축산식품학회지
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• 제43권6호
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• pp.1017-1030
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• 2023

Fetal bovine serum (FBS), which contains various nutrients, comprises 20% of the growth medium for cell-cultivated meat. However, ethical, cost, and scientific issues, necesitates identification of alternatives. In this study, we investigated commercially manufactured serum-free media capable of culturing Hanwoo satellite cells (HWSCs) to identify constituent proliferation enhancing factors. Six different serum-free media were selected, and the HWSC proliferation rates in these serum-free media were compared with that of control medium supplemented with 20% FBS. Among the six media, cell proliferation rates were higher only in StemFlex^TM Medium (SF) and Mesenchymal Stem Cell Growth Medium DXF (MS) than in the control medium. SF and MS contain high fibroblast growth factor 2 (FGF2) concentrations, and we found upregulated FGF2 protein expression in cells cultured in SF or MS. Activation of the fibroblast growth factor receptor 1 (FGFR1)-mediated signaling pathway and stimulation of muscle satellite cell proliferation-related factors were confirmed by the presence of related biomarkers (FGFR1, FRS2, Raf1, ERK, p38, Pax7, and MyoD) as indicated by quantitative polymerase chain reaction, western blotting, and immunocytochemistry. Moreover, PD173074, an FGFR1 inhibitor suppressed cell proliferation in SF and MS and downregulated related biomarkers (FGFR1, FRS2, Raf1, and ERK). The promotion of cell proliferation in SF and MS was therefore attributed to FGF2, which indicates that FGFR1 activation in muscle satellite cells may be a target for improving the efficiency of cell-cultivated meat production.

• Biomolecules & Therapeutics
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• 제32권2호
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• pp.224-230
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• 2024

Pinitol (3-O-Methyl-D-chiro-inositol) has been reported to possess insulin-like effects and is known as one of the anti-diabetic agents to improve muscle, liver, and endothelial cells. However, the beneficial effects of pinitol on the skin are not well known. Here, we investigated whether pinitol had effects on human dermal fibroblasts (HDFs), and human dermal equivalents (HDEs) irradiated with ultraviolet A (UVA), which causes various damages including photodamage in the skin. We observed that pinitol enhanced wound healing in UVA-damaged HDFs. We also found that pinitol significantly antagonized the UVA-induced up-regulation of matrix metalloproteinase 1 (MMP1), and the UVA-induced down-regulation of collagen type I and tissue inhibitor of metalloproteinases 1 (TIMP1) in HDEs. Electron microscopy analysis also revealed that pinitol remarkably increased the number of collagen fibrils with regular banding patterns in the dermis of UVA-irradiated human skin equivalents. Pinitol significantly reversed the UVA-induced phosphorylation levels of ERK and JNK but not p38, suggesting that this regulation may be the mechanism underlying the pinitol-mediated effects on UVA-irradiated HDEs. We also observed that pinitol specifically increased Smad3 phosphorylation, which is representative of the TGF-β signaling pathway for collagen synthesis. These data suggest that pinitol exerts several beneficial effects on UVA-induced damaged skin and can be used as a therapeutic agent to improve skin-related diseases.

• IMMUNE NETWORK
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• 제20권3호
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• pp.25.1-25.13
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• 2020

Acinetobacter baumannii is known for its multidrug antibiotic resistance. New approaches to treating drug-resistant bacterial infections are urgently required. Cathelicidin-related antimicrobial peptide (CRAMP) is a murine antimicrobial peptide that exerts diverse immune functions, including both direct bacterial cell killing and immunomodulatory effects. In this study, we sought to identify the role of CRAMP in the host immune response to multidrug-resistant Acinetobacter baumannii. Wild-type (WT) and CRAMP knockout mice were infected intranasally with the bacteria. CRAMP^-/- mice exhibited increased bacterial colony-forming units (CFUs) in bronchoalveolar lavage (BAL) fluid after A. baumannii infection compared to WT mice. The loss of CRAMP expression resulted in a significant decrease in the recruitment of immune cells, primarily neutrophils. The levels of IL-6 and CXCL1 were lower, whereas the levels of IL-10 were significantly higher in the BAL fluid of CRAMP^-/- mice compared to WT mice 1 day after infection. In an in vitro assay using thioglycollate-induced peritoneal neutrophils, the ability of bacterial phagocytosis and killing was impaired in CRAMP^-/- neutrophils compared to the WT cells. CRAMP was also essential for the production of cytokines and chemokines in response to A. baumannii in neutrophils. In addition, the A. baumannii-induced inhibitor of κB-α degradation and phosphorylation of p38 MAPK were impaired in CRAMP^-/- neutrophils, whereas ERK and JNK phosphorylation was upregulated. Our results indicate that CRAMP plays an important role in the host defense against pulmonary infection with A. baumannii by promoting the antibacterial activity of neutrophils and regulating the innate immune responses.

• Tuberculosis and Respiratory Diseases
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• 제48권2호
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• pp.191-202
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• 2000

목 적: 기관지 천식은 기도의 과민 반응을 특정으로 하는 기도 내 염증 질환이다. 최근 염증반응에 관여하는 cyclooxygease(COX) 에 대해 90년대 초 새로운 형태의 COX2가 발견되었다. 또한 최근 COX2만을 선택적으로 억제하는 약제가 개발되어 이에 대한 연구가 활발히 진행 중이다. 따라서 저자는 기도 내 염증 반응을 특징으로 하는 기관지 천식에서 COX2 발현 양상과 혈중 프로스타글란딘 E2를 측정하고 COX2 억제제를 사용한 후 COX2 발현, 프로스타글란딘 E2의 변화 및 기도 저항의 변화를 알아보았다. 대상 및 방법: 총 38마리의 Sprague-Dawley 백서(250-300g)를 대상으로 정상 대조군, 천식 대조군, 치료군의 3군으로 나누어 실험하였다. 각 세 군에 대해 제 28 연구일에 즉시형 기관지 수축 반응을 유발시킨 후 기도 저항을 측정하였다. 제 30연구일에 혈장 내 프로스타글란딘 E2 수치를 측정하고 기도 및 폐 실질 내 호산구 침윤 정도 및 COX2 면역 조직 화학 염색에 대한 발색 정도를 image analysis를 통해 확인하였다. 결 과: 기관지 및 폐 실질 내 호산구 침윤은 천식 대조군과 치료군의 두 군간에 통계적으로 유의한 차이가 없었다. COX2 면역 조직 화학 염색 및 혈중 프로스타글란딘 E2 농도에 있어서 정상 대조군, 천식 대조군, 치료군의 세 군에서 통계적으로 유의한 차이가 없었다. 치료군에서 nemesulide 투여 후 OVA으로 즉시형 기관지 수축 반응을 일으킨 상태에서 측정한 기도 저항은 nemesulid를 투여하기 전과 비교해서 통계적으로 유의한 차이가 없었다. 결 론: 결론적으로 COX2는 알레르겐 유발성 천식의 병태 생리에 있어서 주된 경로가 아니며 향후 천식 모델에서 COX2 억제제를 사용한 후 lipoxygenase 의한 대사산물과의 상관 관계와 COX2 억제제의 투여하는 방법에 있어서 투여 용량 또는 투여 횟수를 달리하거나 COX2에 대한 선택성이 더 높은 약제를 투여한 후 기도 내 COX2의 변화에 대한 연구가 필요하리라 사료된다.

• 한국약용작물학회지
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• 제11권3호
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• pp.236-245
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• 2003

한국산 백삼으로부터 온도 및 에탄올 함유 비율을 달리하여 조제된 추출물들에 대한 angiotensin converting enzyme (ACE) 저해활성을 검정하고 항산화 활성을 비교하기 위해 본 연구를 수행하였으며 그 결과는 다음과 같다. 1. 10가지 조건에서 얻어진 추출물의 인삼분말에 대한 수율과 총 페놀함량은 $85^{\circ}C$에서 50% 에탄올로 추출했을 때 42.25% 및 0.82%로 가장 높았으며 대체적으로 가온조건이 상온조건보다 높았다. 상온 50% 에탄을 추출물로부터 조제된 분획물의 수율은 물 분획이 72.08%로 가장 높았고, 총 페놀함량은 에틸아세테이트 분획이 6.59%로 가장 높았다. 2. 10가지 추출물의 ACE 저해활성을 실험한 결과 $4000{\mu}g/ml$의 농도에서 상온 50% 에탄올 추출물이 93.8%로 가장 우수한 효과를 보였으며 이 값은 시판 ACE inhibitor의 85.2%보다도 월등하게 높은 수치였으며 분획물은 핵산(201%) > 에텔 (105%) > 에틸아세테이트 (67%) > 부탄올 (46%) < 물 분획 (19%)의 순으로 효과가 높았다. 3. 사람 LDL에 대한 산화저해효과 실험에서는 $85^{\circ}C$에서 얻어진 50% 에탄올 추출물이 $200{\mu}g/ml$의 농도에서 78.2%로 가장 효과적으로 항산화력을 보였으며 모든 추출물들이 60%이상의 높은 산화저해효과를 나타내었다. 분획물에 대한 LDL산화저해효과 검정 실험에서는 에텔 분획물 및 에틸아세테이트 분획물이 $10{\sim}200\;{\mu}g/ml$의 농도에서 $34.38%{\sim}78.13%$로 높은 활성을 보였다. 4. 각 에탄올 추출물의 linoleic acid 과산화저해 및 DPPH라디칼 소거효과는 그다지 높지 않았으며 비교 실험된 시판 천연 항산화제인 ${\alpha}-tocopherol$보다 매우 낮았다. 5 상관분석의 결과 총 페놀함량과 ACE 저해활성은 P<0.05의 수준에서 0.6353의 유의적인 상관성을 나타내었다. 이상의 실험결과로부터 인삼이 ACE 저해 및 LDL산화 저해작용을 효과적으로 나타내고 총 페놀함량이 많이 추출될 수 있으며 수율을 높일 수 있는 가장 적합한 조건은 상온 혹은 가온의 50% 에탄올 추출조건이었으며 인삼은 이러한 활성에 의해 항고혈압 및 동맥경화예방의 효과를 발휘 할 수 있을 것으로 기대되었다.

• 생명과학회지
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• 제19권7호
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• pp.949-955
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• 2009

점막 상피는 외부 인자를 감지하는 최전선의 인식부위로서 외부스트레스 자극을 하부의 반응 신호로 전달하는 주요 세포이다. 리보솜독성 반응을 유발하는 데옥시니발레놀 (DON) 및 그 관련 곰팡이 독소는 푸자륨 곰팡이 오염에 의한 식중독성 소화기 염증성 질환과의 연관성이 알려 져 있다. 본 연구의 목적은 DON이 상피세포 감지 신호 전달 분자로서 PKR과 EGR-1이 관련 되고 이들이 상피세포에서의 염증성 사이토가인 인터루킨 8의 생성에 관련 된다는 가정 하에서 연구를 수행 하였다. PKR 발현의 세포내 작용 억제는 DON에 의해 유도되는 인터루킨 8의 생성을 감소시켰다. 또한 DON에 의한 IL-8 전사 활성화는 PKR 억제에 의하여 장관 상피세포에서 감소하였다. PKR 저해제의 처리는 EGR-1 promoter 활성, mRNA, 단백질 유도 등을 감소를 유발하였으며 MAP kinase (ERK1/2, p38, JNK)는 변화가 적거나 오히려 PKR 저해제의 전처리에 의하여 항진 되었다. 결론적으로 DON에 의해 자극된 감지신호인 EGR-1은 자체적으로 또는 PKR 신호를 경유하여 인터루킨8의 생산을 항진하는데 주요한 기능을 하였다. 이를 통하여 향후 리보솜 독성 반응과 관련된 소화기 염증유발의 주요한 기전을 제공하고 있다.