• Journal of Microbiology and Biotechnology
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• 제29권11호
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• pp.1817-1829
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• 2019

Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus that causes diarrhea in neonatal piglets. Like other coronaviruses, PDCoV encodes at least three accessory or species-specific proteins; however, the biological roles of these proteins in PDCoV replication remain undetermined. As a first step toward understanding the biology of the PDCoV accessory proteins, we established a stable porcine cell line constitutively expressing the PDCoV NS7 protein in order to investigate the functional characteristics of NS7 for viral replication. Confocal microscopy and subcellular fractionation revealed that the NS7 protein was extensively distributed in the mitochondria. Proteomic analysis was then conducted to assess the expression dynamics of the host proteins in the PDCoV NS7-expressing cells. High-resolution two-dimensional gel electrophoresis initially identified 48 protein spots which were differentially expressed in the presence of NS7. Seven of these spots, including two up-regulated and five down-regulated protein spots, showed statistically significant alterations, and were selected for subsequent protein identification. The affected cellular proteins identified in this study were classified into functional groups involved in various cellular processes such as cytoskeleton networks and cell communication, metabolism, and protein biosynthesis. A substantial down-regulation of α-actinin-4 was confirmed in NS7-expressing and PDCoV-infected cells. These proteomic data will provide insights into the understanding of specific cellular responses to the accessory protein during PDCoV infection.

• BMB Reports
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• 제41권6호
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• pp.415-434
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• 2008

Phosphoinositide-specific phospholipase C is an effector molecule in the signal transduction process. It generates two second messengers, inositol-1,4,5-trisphosphate and diacylglycerol from phosphatidylinositol 4,5-bisphosphate. Currently, thirteen mammal PLC isozymes have been identified, and they are divided into six groups: PLC-$\beta$, -$\gamma$, -$\delta$, -$\varepsilon$, -$\zeta$ and -$\eta$. Sequence analysis studies demonstrated that each isozyme has more than one alternative splicing variant. PLC isozymes contain the X and Y domains that are responsible for catalytic activity. Several other domains including the PH domain, the C2 domain and EF hand motifs are involved in various biological functions of PLC isozymes as signaling proteins. The distribution of PLC isozymes is tissue and organ specific. Recent studies on isolated cells and knockout mice depleted of PLC isozymes have revealed their distinct phenotypes. Given the specificity in distribution and cellular localization, it is clear that each PLC isozyme bears a unique function in the modulation of physiological responses. In this review, we discuss the structural organization, enzymatic properties and molecular diversity of PLC splicing variants and study functional and physiological roles of each isozyme.

• Molecules and Cells
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• 제28권1호
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• pp.37-42
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• 2009

Iron binding lactoferrin (Lf) is involved in the control of cell cycle progression. However, the molecular basis underlying the effects of Lf on cell cycle control, as well as its target genes, remains incompletely understood. In this study, we have demonstrated that a relatively low level of ironsaturated Lf, Lf($Fe^{3+}$), can stimulate S phase cell cycle entry, and requires Akt activation in MCF-7 cells. Lf($Fe^{3+}$) immediately induced Akt phosphorylation at Ser473, which subsequently induced the phosphorylation of two G1-checkpoint Cdk inhibitors, $p21^{Cip/WAF1}$ and $p27^{kip1}$. The Lf($Fe^{3+}$)-induced phosphorylation of Cdk inhibitors impaired their nuclear import behavior, thereby inducing cell cycle progression. However, the treatment of cells with a PI3K inhibitor, LY294002, almost completely blocked Lf($Fe^{3+}$)-stimulated cell cycle progression. LY294002 treatment abrogated Lf($Fe^{3+}$)-induced Akt activation, and prevented the cytoplasmic localization of $p27^{kip1}$. Higher levels of $p21^{Cip/WAF1}$ were also detected in the cytoplasmic sub-cellular compartment as a measure of cellular response to Lf($Fe^{3+}$). Consequently, the degree of phosphorylation of retinoblastoma protein was enhanced in response to Lf($Fe^{3+}$). Therefore, we conclude that Lf($Fe^{3+}$), as a potential antagonist of Cdk inhibitors, can facilitate the functions of E2F during progression to S phase via the Akt signaling pathway.

• Journal of Plant Biology
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• 제35권3호
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• pp.219-227
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• 1992

지질성 종자(해바라기, 피마자, 잣나무)와 전분성 종자(완두, 옥수수)를 대상으로 배유와 자엽세포내의 저장지질의 형성, 분포 및 구조적 변화 등과 지질가수분해효소의 활성부위 및 세포내 분포양상 등을 세포화학적 방법을 이용하여 조사하였다. 채종후의 지질 및 전분성 종자의 배유와 저장성 자엽세포에는 구형의 단백과립과 지질소구인 스페로솜, 전분과립 등의 저장물질이 널리 분포하였으며 세포내소기관은 드물게 관찰되었다. 활면소포체에서 형성되어 방출된 소포들과 스페로솜의 초기 단계로 여겨지는, 전자밀도가 낮은 막성의 과립들은 염색상이 스페로솜의 그것과 동일하였다. 조면소포체에서 방출된 전자밀도가 높은 과립들은 원형질막의 인접부위에서 관찰되었다. 지질염색반응 결과, 일반적인 미세구조의 염색상과는 상이하게 단백과립내의 단백질보다는 구형의 스페로솜의 전자밀도가 높고 균일함이 확인되어 스페로솜의 주요 구성성분은 지질임을 알 수 있었다. 스페로솜과 활면소포체에서 방출하는 물질을 함유한 소포는 염색상이 동일하였다. 지질가수분해효소는 분해과정이 진행중인 스페로솜의 기질과 막 주변부, 그리고 원형질막 부근에서 강한 활성을 보였다.

• Molecules and Cells
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• 제39권7호
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• pp.566-572
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• 2016

Lysosomes are cellular organelles containing diverse classes of catabolic enzymes that are implicated in diverse cellular processes including phagocytosis, autophagy, lipid transport, and aging. Lysosome-associated membrane proteins (LAMP-1 and LAMP-2) are major glycoproteins important for maintaining lysosomal integrity, pH, and catabolism. LAMP-1 and LAMP-2 are constitutively expressed in Salmonella-infected cells and are recruited to Salmonella-containing vacuoles (SCVs) as well as Salmonella- induced filaments (Sifs) that promote the survival and proliferation of the Salmonella. LAMP-3, also known as DC-LAMP/CD208, is a member of the LAMP family of proteins, but its role during Salmonella infection remains unclear. DNA microarray analysis identified LAMP-3 as one of the genes responding to LPS stimulation in THP-1 macrophage cells. Subsequent analyses reveal that LPS and Salmonella induced the expression of LAMP-3 at both the transcriptional and translational levels. Confocal Super resolution N-SIM imaging revealed that LAMP-3, like LAMP-2, shifts its localization from the cell surface to alongside Salmonella. Knockdown of LAMP-3 by specific siRNAs decreased the number of Salmonella recovered from the infected cells. Therefore, we conclude that LAMP-3 is induced by Salmonella infection and recruited to the Salmonella pathogen for intracellular proliferation.

• 국제지역연구
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• 제12권3호
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• pp.367-390
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• 2008

중국 휴대폰시장 성장은 한국 이동통신 산업에 기회와 위협을 주는 양면적인 성격을 지니고 있다. 수출시장으로서의 중요성과 함께 중국 휴대폰 산업과의 경합성도 점차 거세지고 있다. 이는 기업의 복합적인 요소를 고려한 소비자 소비성향과 구매의도 파악에 기초한 국제마케팅전략 수립의 현지화를 요구한다. 본 연구에서는 중국 진출을 계획하거나 중국에 이미 진출해 있는 한국 기업에게 전략적 시사점을 제공하는데 그 목적이 있다. 실증분석에서 가설검증 결과를 살펴보면 다음과 같다. 가설 1'기업이미지는 구매의도에 정(+)의 영향을 미칠 것이다'라는 가설이 채택되었다. 가설 2'브랜드이미지는 구매의도에 정(+)의 영향을 미칠 것이다'라는 가설도 채택되었다. 가설 3'제품속성은 구매의도에 정(+)의 영향을 미칠 것이다'라는 가설도 채택되었다. 조절변수인 인구통계학적 특성을 고려한 세 독립변수가 구매의도에 미치는 영향의 차이를 검증한 결과에서 성별, 연령이 기각되었고 학력이 부분채택 되었으며 기타 연구가설이 모두 채택된다. 실증분석에서 사용된 소비자에 대한 측정항목을 중심으로 실제에 적용 가능한 전략을 제시하였다.

• International Journal of Oral Biology
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• 제45권4호
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• pp.190-196
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• 2020

Several factors, including genetic and environmental insults, impede protein folding and secretion in the endoplasmic reticulum (ER). Accumulation of unfolded or mis-folded protein in the ER manifests as ER stress. To cope with this morbid condition of the ER, recent data has suggested that the intracellular event of an unfolded protein response plays a critical role in managing the secretory load and maintaining proteostasis in the ER. Tauroursodeoxycholic acid (TUDCA) is a chemical chaperone and hydrophilic bile acid that is known to inhibit apoptosis by attenuating ER stress. Numerous studies have revealed that TUDCA affects hepatic diseases, obesity, and inflammatory illnesses. Recently, molecular regulation of ER stress in tooth development, especially during the secretory stage, has been studied. Therefore, in this study, we examined the developmental role of ER stress regulation in tooth morphogenesis using in vitro organ cultivation methods with a chemical chaperone treatment, TUDCA. Altered cellular events including proliferation, apoptosis, and dentinogenesis were examined using immunostaining and terminal deoxynucleotidyl transferase dUTP nick end labeling assay. In addition, altered localization patterns of the formation of hard tissue matrices related to molecules, including amelogenin and nestin, were examined to assess their morphological changes. Based on our findings, modulating the role of the chemical chaperone TUDCA in tooth morphogenesis, especially through the modulation of cellular proliferation and apoptosis, could be applied as a supporting data for tooth regeneration for future studies.

• Molecules and Cells
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• 제20권1호
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• pp.112-118
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• 2005

It was previously shown that AtNAP1 is a plastidic SufB protein involved in Fe-S cluster assembly in Arabidopsis. In this study, we investigated the effects of depleting SufB protein from plant cells using virus-induced gene silencing (VIGS). VIGS of NbNAP1 encoding a Nicotiana benthamiana homolog of AtNAP1 resulted in a leaf yellowing phenotype. NbNAP1 was expressed ubiquitously in plant tissues with the highest level in roots. A GFP fusion protein of the N-terminal region (M1-V103) of NbNAP1 was targeted to chloroplasts. Depletion of NbNAP1 resulted in reduced numbers of chloroplasts of reduced size. Mitochondria also seemed to be affected. Despite the reduced number and size of the chloroplasts in the NbNAP1 VIGS lines, the expression of many nuclear genes encoding chloroplast-targeted proteins and chlorophyll biosynthesis genes remained unchanged.

• BMB Reports
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• 제43권2호
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• pp.103-109
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• 2010

Modification of proteins by the reversible covalent addition of the small ubiquitin like modifier (SUMO) protein has important consequences affecting target protein stability, sub-cellular localization, and protein-protein interactions. SUMOylation involves a cascade of enzymatic reactions, which resembles the process of ubiquitination. In this study, we characterized the SUMOylation system from an important crop plant, rice, and show that it responds to cold, salt and ABA stress conditions on a protein level via the accumulation of SUMOylated proteins. We also characterized the transcriptional regulation of individual SUMOylation cascade components during stress and development. During stress conditions, majority of the SUMO cascade components are transcriptionally down regulated. SUMO conjugate proteins and SUMO cascade component transcripts accumulated differentially in various tissues during plant development with highest levels in reproductive tissues. Taken together, these data suggest a role for SUMOylation in rice development and stress responses.

• Journal of Plant Biology
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• 제39권2호
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• pp.99-105
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• 1996

Immunocytochemistry utilizes the specificity of the antigen-antibody reaction to localize specific antigens in cells or cellular organelles. Here we report the use of monoclonal antibodies, in conjunction with gold-labeled second antibodies to study the ultrastructural localization and tissue distribution of the Mr 98, 000 anionic peroxidase and other wall antigens. The antibody specific for this wall peroxidase, mWP3, labeled mainly the cell wall area. At the tissue level, the Mr 98, 000 peroxidase is located predominantly in the leaf mesophyll, internal coleoptile and sieve elements, but not in the root, as assayed with these procedures. The coleoptile walls were less heavily stained than the walls of leaf mesophyll cells. At the subcellular level, it is localized mainly in intercellular regions of the cell walls. A similar staining pattern was revealed by mWP19, one of anti-$\beta$ glucosidase antibody, though it looked less heavily stained than one with mWP3. In order to serve as a control wall staining using IgM monoclonal antibodies, mWP18 was used. Most of the label is localized over wall regions of cells of the young leaf mesophyll and coleoptile.