• Molecules and Cells
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• 제41권3호
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• pp.234-243
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• 2018

In recent years, the interest towards the relationship between incretins and bone has been increasing. Previous studies have suggested that glucagon-like peptide-1 (GLP-1) and its receptor agonists exert beneficial anabolic influence on skeletal metabolism, such as promoting proliferation and differentiation of osteoblasts via entero-osseous-axis. However, little is known regarding the effects of GLP-1 on osteoblast apoptosis and the underlying mechanisms involved. Thus, in the present study, we investigated the effects of liraglutide, a glucagon-like peptide-1 receptor agonist, on apoptosis of murine MC3T3-E1 osteoblastic cells. We confirmed the presence of GLP-1 receptor (GLP-1R) in MC3T3-E1 cells. Our data demonstrated that liraglutide inhibited the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, as detected by Annexin V/PI and Hoechst 33258 staining and ELISA assays. Moreover, liraglutide upregulated Bcl-2 expression and downregulated Bax expression and caspase-3 activity at intermediate concentration (100 nM) for maximum effect. Further study suggested that liraglutide stimulated the phosphorylation of AKT and enhanced cAMP level, along with decreased phosphorylation of $GSK3{\beta}$, increased ${\beta}-catenin$ phosphorylation at Ser675 site and upregulated nuclear ${\beta}-catenin$ content and transcriptional activity. Pretreatment of cells with the PI3K inhibitor LY294002, PKA inhibitor H89, and siRNAs GLP-1R, ${\beta}-catenin$ abrogated the liraglutide-induced activation of cAMP, AKT, ${\beta}-catenin$, respectively. In conclusion, these findings illustrate that activation of GLP-1 receptor by liraglutide inhibits the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation through $cAMP/PKA/{\beta}-catenin$ and $PI3K/Akt/GSK3{\beta}$ signaling pathways.

• The Korean Journal of Physiology and Pharmacology
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• 제25권6호
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• pp.585-592
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• 2021

Cisplatin has been reported to cause side effects such as muscle wasting in humans and rodents. The physiological mechanisms involved in preventing muscle wasting, such as the regulation of AKT, PGC1-α, and autophagy-related factor FOXO3a by MuRF 1 and Atrogin-1, remain unclear following different types of exercise and in various skeletal muscle types. Eight-week-old male Wistar rats (n = 34) were assigned to one of four groups: control (CON, n = 6), cisplatin injection (1 mg/kg) without exercise (CC, n = 8), cisplatin (1 mg/kg) + resistance exercise (CRE, n = 9) group, and cisplatin (1 mg/kg) + aerobic exercise (CAE, n = 11). The CRE group performed progressive ladder exercise (starting with 10% of body weight on a 1-m ladder with 2-cm-interval grids, at 85°) for 8 weeks. The CAE group exercised by treadmill running (20 m/min for 60 min daily, 4 times/week) for 8 weeks. Compared with the CC group, the levels of the autophagy-related factors BNIP3, Beclin 1, LC3-II/I ratio, p62, and FOXO3a in the gastrocnemius and soleus muscles were significantly decreased in the CRE and CAE groups. The CRE and CAE groups further showed significantly decreased MuRF 1 and Atrogin-1 levels and increased phosphorylation of AKT, FOXO3a, and PGC1-α. These results suggest that both ladder and aerobic exercise directly affected muscle wasting by modulating the AKT/PGC1-α/FOXO3a signaling pathways regardless of the skeletal muscle type.

• 한국자원식물학회지
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• 제34권3호
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• pp.203-215
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• 2021

Bok choy is one of Brassica vegetables widely consumed worldwide. Brassica vegetables have been reported to exert various pharmacological activities such as antioxidant, anti-cancer and cardioprotective activity. However, studies on immunostimulatory activity of bok choy sprout have not been conducted properly. Thus, in this study, we investigated in vitro immunostimulatory activity of bok choy sprout extract (BCS) using mouse macrophage RAW264.7 cells. Our results showed that BCS increased the production of immunomodulators such as NO, iNOS, IL-1β, IL-6, IL-12, TNF-α and MCP-1, and phagocytic activity in RAW264.7 cells. BCS activated MAPK, NF-κB and PI3K/AKT signaling pathways. However, BCS-mediated production of immunomodulators was dependent on JNK, NF-κB and PI3K/AKT signaling pathways. the mRNA expression of TLR2 were significantly increased by BCS, TLR2 inhibition by anti-TLR2 dramatically suppressed the production of immunomodulators by BCS. In addition, TLR2 inhibition by anti-TLR2 significantly reduced BCS-mediated phosphorylation level of AKT, JNK and NF-κB. From these results, BCS may have immunostimulatory activity via TLR2-MAPK, NF-κB and PI3K/AKT signaling pathways. Therefore, BCS expected to be used as a potential immune-enhancing agent.

• Anatomy and Cell Biology
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• 제57권1호
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• pp.70-84
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• 2024

Methamphetamine (METH) can potentially disrupt neurotransmitters activities in the central nervous system (CNS) and cause neurotoxicity through various pathways. These pathways include increased production of reactive nitrogen and oxygen species, hypothermia, and induction of mitochondrial apoptosis. In this study, we investigated the long-term effects of METH addiction on the structural changes in the amygdala of postmortem human brains and the involvement of the brain- cAMP response element-binding protein/brain-derived neurotrophic factor (CREB/BDNF) and Akt-1/GSK3 signaling pathways. We examined ten male postmortem brains, comparing control subjects with chronic METH users, using immunohistochemistry, real-time polymerase chain reaction (to measure levels of CREB, BDNF, Akt-1, GSK3, and tumor necrosis factor-α [TNF-α]), Tunnel assay, stereology, and assays for reactive oxygen species (ROS), glutathione disulfide (GSSG), and glutathione peroxidase (GPX). The findings revealed that METH significantly reduced the expression of BDNF, CREB, Akt-1, and GPX while increasing the levels of GSSG, ROS, RIPK3, GSK3, and TNF-α. Furthermore, METH-induced inflammation and neurodegeneration in the amygdala, with ROS production mediated by the CREB/BDNF and Akt-1/GSK3 signaling pathways.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.168.2-168.2
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• 2003

Akt/Ptotein Kinase B (PKB) is a serine/threonine kinase and activated by PI3K pathway. Akt/PKB regulates a variety of cellular responses including proliferations, differentiations and insulin signaling pathway. Recent evidence also indicates that the abnormal activities or expression of Akt/PKB is closely associated with cancer, diabetes and neuro-degenerative diseases. These findings mean that Akt/PKB is likely to be a new therapeutic target for the treatment of disease. (omitted)

• 생명과학회지
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• 제25권9호
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• pp.984-992
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• 2015

혈근초(Sanguinaria canadensis)에서 처음 분리된 sanguinarine은 항산화, 항암 및 면역 증강 등의 효능이 있는 것으로 알려진 alkaloid 계열 물질 중의 하나이다. 본 연구에서는 인체간암 HepG2 세포를 대상으로 sanguinarine의 apoptosis 유도 효능 및 관련 기전 해석을 시도하였다. 본 연구의 결과에 의하면 sanguinarine은 HepG2 간암세포의 증식을 처리 농도 의존적으로 억제하였으며, 이는 apoptosis 유도와 연관성이 있었다. Sanguinarine에 의한 apoptosis 유도에는 Fas 및 Bax의 발현 증가, 미토콘드리아에서 세포질로의 cytochrome c 유리 및 MMPl (Δψm)의 소실을 동반하였다. Sanguinarine은 intrinsic 및 extrinsic apoptosis pathway의 활성에 관여하는 initiator caspase인 caspase-9와 -8의 활성과 effector caspase인 caspase-3의 활성 및 PARP 단백질의 단편화를 유발하였다. Sanguinarine은 또한 ROS의 생성을 촉진시켰으며, N-acetylcysteine 처리에 의한 ROS의 생성을 차단하였을 경우, sanguinarine에 의한 apoptosis 효능이 완벽하게 차단되었다. 아울러 sanguinarine은 Akt의 인산화를 억제한 반면, MAPKs의 인산화를 촉진시켰으며, 특히 PI3K와 ERK의 선택적 억제제는 sanguinarine에 의한 HepG2 간암세포의 증식을 더욱 억제시켰다. 따라서 sanguinarine에 의한 HepG2 간암세포의 apoptosis 유발에는 ROS 생성 의존적인 intrinsic 및 extrinsic signaling pathway가 동시에 활성화되며, PI3K/Akt 및 ERK 신호계가 관여함을 알 수 있었다.

• 한국식품영양과학회지
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• 제45권12호
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• pp.1708-1716
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• 2016

Akt 및 mTOR는 세포 생존에 필수적인 경로로 세포 성장과 증식 등에서 중요한 역할을 하는 것으로 알려져 있다. 본 연구에서는 항암 및 항균 효과가 있는 것으로 알려진 개똥쑥(Artemisia annua L.)에 의한 HepG2 간암세포의 apoptosis 유도 효과를 확인하였다. 본 연구 결과에 의하면 개똥쑥 추출물의 처리 농도가 증가함에 따라 HepG2 세포의 생존율은 억제되었으며, 이는 apoptosis 유도 효과에 의한 것임을 세포의 형태적 변화와 flow cytometry를 통해 확인하였다. 그리고 mitopotential assay와 caspase-3/7 activity assay, western blotting으로 Bcl-2 family 단백질을 확인함으로써 apoptosis 경로 중 내인성 경로(intrinsic pathway)에 의해 apoptosis가 일어남을 알 수 있었다. 이러한 효과는 Akt/mTOR의 활성 저해와 연관이 있었으며 Akt/mTOR의 저해제인 LY294002/rapamycin을 개똥쑥 추출물과 병행처리하였을 경우 개똥쑥 추출물에 의한 apoptosis 효과를 더욱 증대시켰다. 따라서 Akt/mTOR의 저해는 개똥쑥 추출물의 apoptosis 효과를 상승시켰으며 이에 따라 미토콘드리아의 기능 손상과 caspase 활성의 증가를 통해 이루어짐을 확인하였다.

• 생명과학회지
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• 제33권2호
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• pp.129-137
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• 2023

활성산소는 세포의 다양한 생리활성에 중요한 역할을 수행한다. 본 연구에서는 리소포스파티드산에 의해 유도되는 SKOV-3 세포의 이동을 조절하는 신호전달 기전 연구를 수행하였다. IGF-1 및 LPA는 처리시간 그리고 용량 의존적으로 SKOV-3 세포의 이동을 촉진시켰으며, 리소포스파티드산은 이에 따라 Akt의 인산화도 촉진하였다. 리소포스파티드산에 의한 세포이동은 리소포스파티드산 수용체 억제제에 의해 길항되었으나 IGF-1에 의한 세포이동에는 영향이 없었다. PI3K 및 ROCK의 억제는 리소포스파티드산에 의한 세포의 이동을 길항하였으나 MAPK 억제제에 의해서는 길항되지 않았다. 리소포스파티드산에 의해 형성되는 활성산소는 PI3K 및 ROCK의 억제제에 의해 길항되었으며 활성산소를 킬레이트화하면 리소포스파티드산에 의한 세포의 이동이 억제되었다. 또한 리간드에 의해 활성산소를 형성하는 NOX를 억제하면 리소포스파티드산에 의한 세포의 이동도 억제 되는 것이 관찰되었다. Rictor 및 Akt1의 발현을 억제하면 활성산소 및 세포의 이동이 저해되었으나 Raptor 및 Akt2의 발현조절은 모두 영향이 없는 것으로 관찰되었다. 마지막으로 우성활성화형태인 Akt1의 과발현은 리소포스파티드산의 자극이 없어도 SKOV-3 세포의 이동을 촉진하는 것으로 관찰되었다. 이러한 결과들을 바탕으로 리소포스파티드산은 mTORC2/Akt1/NOX 신호전달 기전을 통해 활성산소를 형성하고 SKOV-3 난소암세포의 이동을 촉진한다는 것을 제안한다.

• 동의생리병리학회지
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• 제21권1호
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• pp.86-92
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• 2007

Hibiscus sabdariffa L., a tropical beverage material, is used commonly as in folk medicine against hypertension, pyrexia, inflammation, liver disorders, and obesity. However, the mechanism by which Hibiscus sabdariffa L. modulates adipogenic differentiation is remained to be elusive. This report was designed to investigate the inhibitory effect of Hibiscus extract on insulin signaling pathway during adipocyte differentiation in 3T3-L1 preadipocytes. 3T3-L1 preadipocytes were differentiated with isobutylmethylxanthine, dexamethasone, and insulin (MDI) and followed by the addition of Hibiscus extract. Treatment with Hibiscus resulted in a decrease of lipid droplet accumulation, which was suppressed by PI-3 kinase inhibitor wortmannin in 3T3-L1 preadipocytes. Also, Hibiscus extract markedly attenuated the mRNA expression of adipogenic transcriptional factor PPAR${\gamma}$ and adipogenic hormon Leptin during adipogenesis. However, it did not affect the expression of adiponectin in 3T3-L1 preadipocytes differentiated with MDI mixture. Furthermore, Adipogenic differentiation by MDI mixture increased the phosphorylation and expression of PI3-Kinase and Akt in 3T3 preadipocytes, which was markedly suppressed by Hibiscus extract treatment. Taken together, our results suggest that Hibiscus extract suppressed the adipogenic differentiation of 3T3 preadipocytes through activation of PI3-Kinase and Akt signaling pathway.

• Asian Pacific Journal of Cancer Prevention
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• 제15권17호
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• pp.7245-7249
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• 2014

Glucose regulated protein 78 (GRP78) is usually recognized as a chaperone in the endoplasmic reticulum. However, increasing evidence indicates that GRP78 can be translocated to the cell surface, acting as a signaling receptor for a variety of ligands. Since little is known about the secretion of GRP78 and its role in the progression of colon cancer we here focused on GRP78 from colon cancer cells, and purified GRP78 protein mimicking the secreted GRP78 was able to utilize cell surface GRP78 as its receptor, activating downstream PI3K/Akt and Wnt/${\beta}$-catenin signaling and promote colon cancer cell proliferation. Our study revealed a new mode of action of autocrine GRP78 in cancer progression: secreted GRP78 binds to cell surface GRP78 as its receptor and activates intracellular proliferation signaling.