• Journal of Life Science
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• v.33 no.9
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• pp.754-765
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• 2023

Exosomes are a type of extracellular vesicle containing proteins and messenger and microRNAs; they are secreted by all cell types. Once released, exosomes are selectively taken up by other cells adjacent or at a distance, releasing their contents and reprogramming the target cells. Since exosomes are natural vesicles produced by cells as small sizes, it is generally accepted that exosomes have a non-toxic nature and non-immunogenic behaviors. Recently, exosomes have elicited scientific attention as drug delivery vehicles to the central nervous system. The central nervous system has a blood-brain barrier that makes it difficult for drugs to penetrate. Thus, the blood-brain barrier has been a major obstacle to the development of drugs for treating neurodegenerative diseases. However, accumulating evidence suggests that exosomes can cross the blood-brain barrier primarily through transcytosis. Consequently, exosomes are expected to become a new delivery vehicle that can cross the blood-brain barrier and deliver drugs into the brain parenchyma. In addition, since different types of exosomes are secreted depending on the cell type and disease state, exosomes can also be utilized as biomarkers for the diagnosis of diseases in the central nervous system. In this review, we summarized recent research trends on exosomes, including clinical trials as biomarkers and treatment options for diseases in the central nervous system.

• Journal of Applied Biological Chemistry
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• v.61 no.2
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• pp.205-211
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• 2018

Rebaudioside A is a natural sweetener isolated from Stevia rebaudiana Bertoni, one of the glycosides based on steviol. Recent studies have shown that rebaudioside A inhibits the inflammatory response by inhibiting cytokines secretion such as interleukin-$1{\alpha}/1{\beta}$ in activated RAW264.7 mouse macrophage cells by LPS. However, the inhibitory mechanism of inflammation by rebaudioside A in the presence of LPS has not been fully elucidated. Therefore, in this study, we tried to investigate the anti-inflammatory activity of rebaudioside A at the protein level when RAW264.7 cells were stimulated by LPS. The inducible nitric oxide synthase protein expression level was reduced in the group treated with $250{\mu}M$ rebaudioside A compared to the LPS-treated group. In addition, the mRNA expression level of $NF-{\kappa}B$, which is a representative nuclear transcription factor by inflammatory signal, was also decreased as compared with that of LPS-treated group. In addition, $NF-{\kappa}B$ and inhibitor-${\kappa}B$ ($I-{\kappa}B$) complexes that are known to be dissociated by $I-{\kappa}B$ phosphorylation and ubiquitination were less phosphorylated than LPS treated group in the presence rebaudioside A. Finally, we could find that rebaudioside A was involved in the $NF-{\kappa}B$ pathway through reducing extracellular signal-regulated kinase1/2 phosphorylation in a concentration-dependent manner. These results suggest that rebaudioside A might suppress inflammatory reaction through MAPK and $NF-{\kappa}B$ regulation in LPS-stimulated RAW264.7.

• Journal of Life Science
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• v.26 no.3
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• pp.364-375
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• 2016

Post-translational modification is an efficient process to rapidly transduce external stimulus into cellular response. Ubiquitination is a typical post-translational modification which is a highly conserved process in eukaryotes. UPS (Ubiquitin/Proteasome System) mediated by the ubiquitination is to target diverse cellular proteins for degradation. Among E3 ubiquitin ligases that function as the key determinant for substrate recognition, CRL (cullin–RING E3 ubiquitin ligase) is the largest family and forms the complex composed of cullin, RBX1, adaptor and substrate receptor. Although CRL1, also known as SCF complex, has been widely researched for its biological role, the functional studies of CRL4 have been relatively elusive. In Arabidopsis, there are 119 substrate receptors named DCAF (DDB1 CUL4 Associated Factor) proteins for CRL4 and a fraction of DCAF proteins have been identified for their potential functions so far. In this paper, current understanding on structure and biological roles of plant CRL4 complexes in a diverse of cellular events is reviewed, especially focusing on CRL4 substrate receptors. Moreover, the regulatory mechanism of CRL4’s activity is also introduced. These studies will be helpful to further understand the signal transduction pathways in which such CRL4 complexes are involved and give a clue to establish the action network of entire CRL4 complexes in plants.

• Journal of Life Science
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• v.32 no.6
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• pp.421-429
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• 2022

The expression of interleukin-1α (IL-1α) is elevated in monocytic cells, such as monocytes and macro-phages, within atherosclerotic arteries, yet the cellular molecules involved in cytokine upregulation remain unclear. Because peptidoglycan (PG), a major component of gram-positive bacterial cell walls, is detected within the inflammatory cell-rich regions of atheromatous plaques, it was investigated if PG contributes to IL-1α expression in monocytes/macrophages. Exposure of THP-1 monocytic cells to PG resulted in elevated levels of IL-1α gene transcripts and increased secretion of IL-1α protein. The transcription and secretion of IL-1α were abrogated by OxPAPC, an inhibitor of TLR2/4, but not by polymyxin B that inhibits lipopolysaccharide-induced TLR4 activation. To understand the molecular mechanisms of the inflammatory responses due to bacterial pathogen-associated molecular patterns (PAMPs) in diseased arteries, we attempted to determine the cellular factors involved in the PG-induced upregulation of IL-1α expression. Pharmacological inhibition of cell signaling pathways with LY294002 (a PI3K inhibitor), Akti IV (an inhibitor of Akt activation), rapamycin (an mTOR inhibitor), U0126 (a MEK inhibitor), SB202190 (a p38 MAPK inhibitor), SP6001250 (a JNK inhibitor), and DPI (a NOX inhibitor) also significantly attenuated the PG-mediated expression of IL-1α. These results suggest that PG induces the monocytic or macrophagic expression of IL-1α, thereby contributing to vascular inflammation, via multiple signaling molecules, including TLR2, PI3K/Akt/mTOR, and MAPKs.

• Journal of Life Science
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• v.33 no.1
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• pp.8-14
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• 2023

Peroxidasin (PXDN), a multidomain heme peroxidase containing extracellular matrix (ECM) motifs, as well as a catalytic domain, catalyzes the sulfilimine crosslink of collagen IV (Col IV) to reinforce Col IV scaffolds. We previously reported that PXDN is required for endothelial cell (EC) survival and growth signaling through sulfilimine crosslink-dependent matrix assembly. In this study, we examined whether peroxidase activity is required for PXDN function in ECs. First, we constructed a mutant PXDN by point mutation of two highly conserved amino acids, Q823 and D826, which are present in the active site of the peroxidase domain. After isolation of HEK293 clones highly expressing the mutant protein, conditioned medium (CM) was obtained after incubating the cells in serum-free medium for 24 hours and then analyzed by Western blot analysis under nonreducing conditions. The results revealed that the mutant PXDN formed a trimer and that it was cleaved by proprotein convertase-like wild-type (WT) PXDN. However, peroxidase activity was not detected in the CM containing the mutant PXDN, in contrast to that of WT PXDN. In addition, the sulfilimine crosslink ability of the mutant PXDN was lost. Moreover, the CM containing the mutant PXDN failed to promote the growth of PXDN-depleted ECs, unlike the CM containing WT PXDN. These results suggest that the peroxidase activity of PXDN affects EC growth by forming a sulfilimine crosslink.

• Korean Journal of Plant Resources
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• v.30 no.5
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• pp.571-577
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• 2017

Abscisic acid (ABA) is an important phytohormone involved in abiotic stress tolerance in plants. The group A bZIP transcription factors play important roles in the ABA signaling pathway in Arabidopsis but little is known about their functions in rice. In our current study, we have isolated and characterized a group A bZIP transcription factor in rice, OsABF3 (Oryza sativa ABA responsive element binding factor 3). We examined the expression patterns of OsABF3 in various tissues and time course analysis after abiotic stress treatments such as drought, salinity, cold, oxidative stress, and ABA in rice. Subcellular localization analysis in maize protoplasts using a GFP fusion vector further indicated that OsABF3 is a nuclear protein. Moreover, in a yeast one-hybrid experiment, OsABF3 was shown to bind to ABA responsive elements (ABREs) and its N-terminal region found to be necessary to transactivate a downstream reporter. A homozygous T-DNA insertional mutant of OsABF3 is more sensitive to salinity, drought, and oxidative stress compared with wild type plants ＆ OsABF3OX plants. In addition, this Osabf3 mutant showed a significantly decreased sensitivity to high levels of ABA at germination and post-germination. Collectively, our present results indicate that OsABF3 functions as a transcriptional regulator that modulates the expression of abiotic stress-responsive genes through an ABA-dependent pathway.

• The Korean Journal of Zoology
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• v.31 no.1
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• pp.62-70
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• 1988

The distribution of respiratory chain complexes in beef heart and human muscle mitochondria has been explored by immunoeledron microscopy with antibodies made against beef heart mltochondriai proteins in conjundion with protein A cofloidai gold (l2nm particles). The antibodies used were made against NADH-conezyme Q reductase(complex I), ubiquinol-cytochrome-c-oxldoreductase (complex III) and cytochrome-c-oxidase(complex IV). Labeling of bed heart tissue with any of these antihodies gave gold particles randomly distributed along the mitochondrial inner membrane. The labeling of muscle tIssue mitochondria from a patient with a mitochondrial myopathy localized by biochemical analysis to complex III was quantitated and compared with the labeling of human control muscle tissue mitochondria. Four kinds of morphological changes in the mitochondrial fine strudure in the myopathy patient tissue have been found; paracrystalline inclusions consistIng of densely packed multi- lamellar structures, globular crystalline inclusions with high electron density, multilamellar strudure inclusion body(compadly and irregularly arranged concentric whirl shaped cristae)and golbular cyrstalilne inclusions located in the center of the whirl shaped cristae. Compex I and cytochrome-c-oxldase antihodies reacted to the same level in the mitochondria containing the crystalline inclusions and control mitochondria. Antibodies to complex III reacted very poorly to the mitochondria containing the crystalline Inclusions but strongly to control mitchondria. The globular crystalline inclusions in the mitochondria are not reacted antibodies to respiratory chain complexes.

• Journal of Life Science
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• v.29 no.7
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• pp.809-816
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• 2019

The ubiquitous plant metabolite p-coumaric acid (p-CA) has antioxidant and anti-inflammatory properties, but its anti-cancer activity has not been established in gastric cancer cell lines. In this study, we investigated the effects of p-CA on the proliferation and transcriptome profile of SNU16 gastric cancer cells. Treatment with p-CA induced apoptosis of the SNU-16 cells by regulating the expression of pro-apoptotic and anti-apoptotic proteins, such as Bcl-2, poly (ADP-ribose) polymerase (PARP), Bax, procaspase-3, and cleaved-caspase-3. The genes differentially expressed in response to p-CA treatment of the SNU-16 cells were identified by RNA sequencing analysis. Genes regulated by p-CA were involved mainly in the inflammatory response, apoptotic processes, cell cycle, and immune response. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the phosphatidylinositol-3-kinase-Akt and cancer signaling pathways were altered by p-CA. Protein-protein interaction (PPI) network analysis also revealed that p-CA treatment was correlated with differential expression of genes associated with the inflammatory response and cancer. Collectively, these results suggest that p-CA has potential utility in gastric cancer prevention.

• Tuberculosis and Respiratory Diseases
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• v.58 no.6
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• pp.590-599
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• 2005

Object : Cigarette smoking is a major cause of mucus hypersecretion, which is a pathophysiological feature of many inflammatory airway diseases. Mucins, which are an important part of the airway mucus, are synthesized from the Muc gene in airway epithelial cells. However, the signaling pathways for cigarette smoke-induced mucin synthesis are unknown. The aim of this study was to determine the signal pathway for smoking induced Muc5ac gene expression. Methods : A549 cells were cultured and transiently transfected with the Muc5ac promoter fragment. These cells were stimulated with 5% cigarette smoke extract (CSE) alone or with CSE after a pretreatment with various signal transduction pathway inhibitors (AG1478, PD98059 and SB203580). The Muc5ac promoter activity was examined using the luciferase reporter system, and the level of phosphorylated EGFR, ERK1/2, p38 MAPK and JNK were all examined using Western blot analysis. Muc5ac mRNA expression was also examined using reverse transcriptase polymerase chain reactions (RT-PCR). Results : 1. The peak level of luciferase activity of the Muc5ac promoter was observed at 5% concentration and after 3 hours of incubation with the CSE. The level of EGFR phosphorylation and the luciferase activity of the transfected cells caused by the CSE were significantly suppressed by AG1478 or PD98059 (P<0.01). 2. CSE phosphorylated ERK1/2 or p38 MAPK but not JNK. The Muc5ac mRNA expression level was increased by the CSE but that was suppressed by PD98059 or AG1478. 3. The CSE-induced phosphorylation of ERK1/2 was blocked by PD98059 and that of p38 MAPK was blocked by either PD98059 or SB203580. Either PD98059 or SB203580 suppressed the luciferase activity of the transfected cells (P<0.0001). Conclusion : The Muc5ac mRNA expression level was increased by the CSE. The increased CSE-induced transcriptional activity was mediated via EGF receptor activation, which led to ERK1/2 and p38 MAPK phosphorylation.

• Journal of Plant Biotechnology
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• v.38 no.2
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• pp.169-175
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• 2011

Calcium ($Ca^{2+}$) signals have been implicated in regulating plant development and responses to the environmental stresses including a programmed cell death pathway. In animals and plants, cytosolic $Ca^{2+}$ signals have been involved in the activation of programmed cell death (PCD). Recently, we reported that disruption of Arabidopsis vacuolar $\b{A}$utoinhibited $\underline{C}a^{2+}$-$\b{A}$TPases (ACAs), ACA4 and ACA11, resulted in the activation of a salicylic acid-dependent programmed cell death pathway. Although extensive studies have revealed various components of a PCD in plants, executors to directly induce PCD are well unknown. Here, we provide that the vacuolar processing enzymes (VPEs) are involved in a PCD induced by the double knockout mutant of vacuolar $Ca^{2+}$-ATPases in Arabidopsis. The gene expression of VPE was rapidly up-regulated and the enzyme activity of VPE was increased in the double mutant plants. We also generated aca4/aca11/avpe, aca4/aca11/${\gamma}$vpe and aca4/aca11/avpe/${\gamma}$vpe mutant plants. Although cell death phenotype of the double mutant plants was not completely disappeared in the triple and quadruple mutant plants, the triple and quadruple mutant plants showed to significantly delay cell death phenotype of the double mutant plants. These results suggest that the VPE is involved in the HR-like cell death in the double mutant of vacuolar $Ca^{2+}$-ATPases in Arabidopsis.