• IMMUNE NETWORK
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• 제9권2호
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• pp.35-40
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• 2009

Although Rap GTPases of the Ras family remained enigmatic for years, extensive studies in this decade have revealed diverse functions of Rap signaling in the control of cell proliferation, differentiation, survival, adhesion, and movement. With the use of gene-engineered mice, we have uncovered essential roles of endogenous Rap signaling in normal lymphocyte development of both T- and B-lineage cells. Deregulation of Rap signaling, on the other hand, results in the development of characteristic leukemia in manners highly dependent on the contexts of cell lineages. These results highlight crucial roles of Rap signaling in the physiology and pathology of lymphocyte development.

• Molecular & Cellular Toxicology
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• 제5권2호
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• pp.147-152
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• 2009

This study was conducted to evaluate the inflammatory mechanisms of LPS-stimulated BV-2 microglial cells. The inflammation mechanism was evaluated in BV-2 cells with or without LPS treated using the Affymetrix microarray analysis system. The microarray analysis revealed that B cell receptor signaling pathway, cytokine-cytokine receptor interaction, Jak-STAT signaling pathway, MAPK signaling pathway, Neuro-active ligand-receptor interaction, TLR signaling path-way, and T cell receptor signaling pathway-related genes were up-regulated in LPS stimulated BV-2 cells. Selected genes were validated using real time RTPCR. These results can help an effective therapeutic approach to alleviating the progression of neuro-in-flammatory diseases.

• 대한약침학회지
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• 제27권2호
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• pp.131-141
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• 2024

Objectives: Polycystic ovary syndrome (PCOS) is one of the most common disorders and it shows up to 20% prevalence in reproductive-aged women populations, but no cures are available to date. We aimed to investigate the protective effects of Changbudodam-tang (CBD) on cell death signaling pathways, inflammation, and oxidative stress observed in Bone-Marrow derived human mesenchymal stem cell (BM-hMSC) by means of PCOS therapeutics in the future. Methods: BM-hMSCs were applied with cell deaths and injuries. Apoptosis and pyroptosis signals were quenched with their related signaling pathways using quantitative PCR, Western blot, and fluorescence image analysis. Results: Our data clearly displayed hydrogen peroxide- and nigericin-treated cell death signaling pathways via regulations of mitochondrial integrity and interleukin (IL)-1β at the cellular levels (p < 0.01 or 0.001). We further observed that pre-treatment with CBD showed protective effects against oxidative stress by enhancement of antioxidant components at the cellular level, with respect to both protein and mRNA expression levels (p < 0.05, 0.01 or 0.001). The mechanisms of CBD were examined by Western blot analysis, and it showed anti-cell death, anti-inflammatory, and antioxidant effects via normalizations of the Jun N-terminal kinase/mitogen-activated protein kinase kinase 7/c-Jun signaling pathways. Conclusion: This study confirmed the pharmacological properties of CBD by regulation of cellular oxidation and the inflammation-provoked cell death condition of BM-hMSCs, which is mediated by the MKK7/JNK/c-Jun signaling pathway.

• IMMUNE NETWORK
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• 제1권3호
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• pp.196-202
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• 2001

Backgorund: WEHI-231 B cell line is a representative model for $IgM^+$ mature B cells. To understand the signaling differences between mature and immature B cells, we compared the responsiveness of WEHI-231 and Bal 17 B cell lines to BCR cross-linking. Methods: The extents of tyrosine phosphorylation, ligand-induced internalization, and activation-induced cell death upon BCR cross-linking were compared in two cell lines. Results: Despite a higher expression of BCR, cross-linking of BCR on WEHI-231 cell evoked a weaker level of tyrosine phosphorylation and BCR endocytosis than Bal 17 cells. Furthermore, the endocytosed BCR could not enter the lysosomal compartment and stayed as peripheral spots in WEHI-231 cells. Conclusion: WEHI-231 cell showed preferred BCR-mediated signaling pathways leading to a reduced capability of antigen presentation as well as the enhanced apoptosis in comparision with Bal 17 cells. These results might reflect the signaling differences between mature and immature B cells.

• BMB Reports
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• 제50권3호
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• pp.132-137
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• 2017

Elevated glucose levels in cancer cells can be attributed to increased levels of glucose transporter (GLUT) proteins. Glut1 expression is increased in human malignant cells. To investigate alternative roles of Glut1 in breast cancer, we silenced Glut1 in triple-negative breast-cancer cell lines using a short hairpin RNA (shRNA) system. Glut1 silencing was verified by Western blotting and qRT-PCR. Knockdown of Glut1 resulted in decreased cell proliferation, glucose uptake, migration, and invasion through modulation of the EGFR/MAPK signaling pathway and integrin ${\beta}1$/Src/FAK signaling pathways. These results suggest that Glut1 not only plays a role as a glucose transporter, but also acts as a regulator of signaling cascades in the tumorigenesis of breast cancer.

• Nutrition Research and Practice
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• 제3권1호
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• pp.64-71
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• 2009

Amino acids are fundamental nutrients for protein synthesis and cell growth (increase in cell size). Recently, many compelling evidences have shown that the level of amino acids is sensed by extra- or intra-cellular amino acids sensor(s) and regulates protein synthesis/degradation. Mammalian target of rapamycin complex 1 (mTORC1) is placed in a central position in cell growth regulation and dysregulation of mTOR signaling pathway has been implicated in many serious human diseases including cancer, diabetes, and tissue hypertrophy. Although amino acids are the most potent activator of mTORC1, how amino acids activate mTOR signaling pathway is still largely unknown. This is partly because of the diversity of amino acids themselves including structure and metabolism. In this review, current proposed amino acid sensing mechanisms to regulate mTORC1 and the evidences pro/against the proposed models are discussed.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-1
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• pp.102-103
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• 2003

Osteoclast are specialized cells derived from the monocyte/macrophage haematopoietic lineage that develop and adhere to bone matrix, then secrete acid and lytic enzymes that degrade it in a specialized, extracellular compartment. Regulation of osteoclast differentiation is central to the understanding of the pathogenesis and treatment of bone diseases such as osteoporosis. (omitted)

• Journal of Communications and Networks
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• 제11권1호
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• pp.26-35
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• 2009

In this paper, we investigate how to do resource allocation to guarantee a minimum user data rate at low signaling overhead in multi-cell orthogonal frequency division multiple access (OFDMA) wireless systems. We devise dynamic resource allocation (DRA) algorithms that can minimize the QoS violation ratio (i.e., the ratio of the number of users who fail to get the requested data rate to the total number of users in the overall network). We assume an OFDMA system that allows dynamic control of frequency reuse factor (FRF) of each sub-carrier. The proposed DRA algorithms determine the FRFs of the sub-carriers and allocate them to the users adaptively based on inter-cell interference and load distribution. In order to reduce the signaling overhead, we adopt a hierarchical resource allocation architecture which divides the resource allocation decision into the inter-cell coordinator (ICC) and the base station (BS) levels. We limit the information available at the ICC only to the load of each cell, that is, the total number of sub-carriers required for supporting the data rate requirement of all the users. We then present the DRA with limited coordination (DRA-LC) algorithm where the ICC performs load-adaptive inter-cell resource allocation with the limited information while the BS performs intra-cell resource allocation with full information about its own cell. For performance comparison, we design a centralized algorithm called DRA with full coordination (DRA-FC). Simulation results reveal that the DRA-LC algorithm can perform close to the DRA-FC algorithm at very low signaling overhead. In addition, it turns out to improve the QoS performance of the cell-boundary users, and achieve a better fairness among neighboring cells under non-uniform load distribution.

• 한국발생생물학회지:발생과생식
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• 제24권2호
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• pp.113-123
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• 2020

Metformin has been widely used as an antidiabetic drug, and reported to inhibit cell proliferation in many cancers including non-small cell lung cancer (NSCLC). In NSCLC cells, metformin suppresses PI3K/AKT/mTOR signaling pathway, but effect of metformin on RAS/RAF/MEK/ERK signaling pathway is controversial; several studies showed the inhibition of ERK activity, while others demonstrated the activation of ERK in response to metformin exposure. Metformin-induced activation of ERK is therapeutically important, since metformin could enhance cell proliferation through RAS/RAF/MEK/ERK pathway and lead to impairment of its anticancer activity suppressing PI3K/AKT/mTOR pathway, requiring blockade of both signaling pathways for more efficient antitumor effect. The present study tested the combination therapy of metformin and trametinib by monitoring the alterations of regulatory effector proteins of cell signaling pathways and the effect of the combination on cell viability in NCI-H2087 NSCLC cells with NRAS and BRAF mutations. We show that metformin alone blocks PI3K/AKT/mTOR signaling pathway but induces the activation and phosphorylation of ERK. The combination therapy synergistically decreased cell viability in treatment with low doses of two drugs, while it gave antagonistic effect with high doses. These findings suggest that the efficacy of metformin and trametinib combination therapy may depend on the alteration of ERK activity induced by metformin and specific cellular context of cancer cells.

• BMB Reports
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• 제51권3호
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• pp.134-142
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• 2018

Organ growth is fundamental to animal development. One of major mechanisms for growth control is mediated by the conserved Hippo signaling pathway initially identified in Drosophila. The core of this pathway in Drosophila consists of a cascade of protein kinases Hippo and Warts that negatively regulate transcriptional coactivator Yorkie (Yki). Activation of Yki promotes cell survival and proliferation to induce organ growth. A key issue in Hippo signaling is to understand how core kinase cascade is activated. Activation of Hippo kinase cascade is regulated in the upstream by at least two transmembrane proteins Crumbs and Fat that act in parallel. These membrane proteins interact with additional factors such as FERM-domain proteins Expanded and Merlin to modulate subcellular localization and function of the Hippo kinase cascade. Hippo signaling is also influenced by cytoskeletal networks and cell tension in epithelia of developing organs. These upstream events in the regulation of Hippo signaling are only partially understood. This review focuses on our current understanding of some upstream processes involved in Hippo signaling in developing Drosophila organs.