• 생물정신의학
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• 제8권1호
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• pp.3-19
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• 2001

Recent basic and clinical studies demonstrate a major role for neural plasticity in the etiology and treatment of depression and stress-related illness. The neural plasticity is reflected both in the birth of new cell in the adult brain(neurogenesis) and the death of genetically healthy cells(apoptosis) in the response to the individual's interaction with the environment. The neural plasticity includes adaptations of intracellular signal transduction pathway and gene expression, as well as alterations in neuronal morphology and cell survival. At the cellular level, repeated stress causes shortening and debranching of dendrite in the CA3 region of hippocampus and suppress neurogenesis of dentate gyrus granule neurons. At the molecular level, both form of structural remodeling appear to be mediated by glucocorticoid hormone working in concert with glutamate and N-methyl-D-aspartate(NMDA) receptor, along with transmitters such as serotonin and GABA-benzodiazepine system. In addition, the decreased expression and reduced level of brain-derived neurotrophic factor(BDNF) could contribute the atrophy and decreased function of stress-vulnerable hippocampal neurons. It is also suggested that atrophy and death of neurons in the hippocampus, as well as prefrontal cortex and possibly other regions, could contribute to the pathophysiology of depression. Antidepressant treatment could oppose these adverse cellular effects, which may be regarded as a loss of neural plasticity, by blocking or reversing the atrophy of hippocampal neurons and by increasing cell survival and function via up-regulation of cyclic adenosine monophosphate response element-binding proteins(CREB) and BDNF. In this article, the molecular and cellular mechanisms that underlie stress, depression, and action of antidepressant are precisely discussed.

• 대한의생명과학회지
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• 제12권1호
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• pp.9-16
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• 2006

We investigated the effects of 835-MHz electromagnetic field (EMF), one of the most popular communication frequency band in Korean code-division multiple-access (CDMA) mobile phone system, on cellular signal transduction. For this, we examined the change of intracellular calcium $([Ca^{2+}]_i)$, reactive oxygen species (ROS) and F-actin polymerization after exposure to 835-MHz EMF followed by the treatment of agonists in Rat-2 fibroblast cells. Culture cells were pretreated with serum-tree medium and concomitantly exposed to 835-MHz at specific absorption rate (SAR) of 4.0 W/kg for 24 hr in a specialized designed apparatus based on Transverse Electro Magnetics (TEM) wave theory. Intracellular $Ca^{2+}$ responses to lysophosphatidic acid (LPA) and epidermal growth factor (EGF) in Rat-2 fibroblast after exposure to 835-MHz EMF were shown to be similar pattern as observed in normal cultured cells. However, the LPA-induced calcium spiking was slightly delayed to 7 sec and sustained thereafter to a little higher ground level under 835-MHz EMF radiation compared to unexposed cells. ROS production level by LPA in the exposed cells was not different from that in control. Furthermore, LPA induced the production of stress fibers with no significant difference in the exposed and unexposed cells. These results suggest that mobile phone radiation (835-MHz, SAR 4.0 W/kg) may not be directly related to signal transduction in Rat-2 fibroblasts except the slight effect of calcium spiking in LPA-induced cells but remain to be further elucidated for possible indirect intervention.

• 한국발생생물학회지:발생과생식
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• 제16권4호
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• pp.235-251
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• 2012

The reproductive activity in male mammals is well known to be regulated by the hypothalamus-pituitary-gonad axis. The hypothalamic neurons secreting gonadotropin releasing hormone (GnRH) govern the reproductive neuroendocrine system by integrating all the exogenous information impinging on themselves. The GnRH synthesized and released from the hypothalamus arrives at the anterior pituitary through the portal vessels, provoking the production of the gonadotropins(follicle-stimulating hormone (FSH) and luteinizing hormone (LH)) at the same time. The gonadotropins affect the gonads to promote spermatogenesis and to secret testosterone. Testosterone acts on the GnRH neurons by a feedback loop through the circulatory system, resulting in the balance of all the hormones by regulating reproductive activities. These hormones exert their effects by acting on their own receptors, which are included in the signal transduction pathways as well. Unexpected aberrants are arised during this course of action of each hormone. This review summarizes these abnormal phenomena, including various mutations of molecules and their actions related to the reproductive function.

• 환경생물
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• 제26권4호
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• pp.377-384
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• 2008

A cell is the product of a long period of evolution and can be represented as an optimized system (homeostasis). Stimuli from the outside environment are received by sensory apparatus on the surface of the cell and transferred through complicated pathways and eventually regulate gene expression. These signals affect cell physiology, growth, and development, and the interaction among genes in the signal transduction pathway is a critical part of the regulation. In this study, the interactions of deletion mutants and overexpression of the extracopies of the genes were used to understand their relationships to each other. Also, green fluorescent protein (GFP reporter gene) was fused to the regulatory genes to elucidate their interactions. Cooverexpression of the two genes in extracopy plasmids suggested that patS acts at the downstream of hetR in the regulatory network. The experiments using gfp fusion in different genetic background cells also indicated the epistasis relationships between the two genes. A model describing the regulatory network that controls cell development is presented.

• Journal of Microbiology
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• 제44권3호
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• pp.284-292
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• 2006

The cbb3 cytochrome c oxidase has the dual function as a terminal oxidase and oxygen sensor in the photosynthetic bacterium, Rhodobacter sphaeroides. The cbb3 oxidase forms a signal transduction pathway together with the PrrBA two-component system that controls photosynthesis gene expression in response to changes in oxygen tension in the environment. Under aerobic conditions the cbb3 oxidase generates an inhibitory signal, which shifts the equilibrium of PrrB kinase/phosphatase activities towards the phosphatase mode. Photosynthesis genes are thereby turned off under aerobic conditions. The catalytic subunit (CcoN) of the R. sphaeroides cbb3 oxidase contains five histidine residues (H2l4, B233, H303, H320, and H444) that are conserved in all CcoN subunits of the cbb3 oxidase, but not in the catalytic subunits of other members of copper-heme superfamily oxidases. H214A mutation of CcoN affected neither catalytic activity nor sensory (signaling) function of the cbb3 oxidase, whereas H320A mutation led to almost complete loss of both catalytic activity and sensory function of the cbb3 oxidase. H233V and H444A mutations brought about the partial loss of catalytic activity and sensory function of the cbb3 oxidase. Interestingly, the H303A mutant form of the cbb3 oxidase retains the catalytic function as a cytochrome c oxidase as compared to the wild-type oxidase, while it is defective in signaling function as an oxygen sensor. H303 appears to be implicated in either signal sensing or generation of the inhibitory signal to the PrrBA two-component system.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.182-185
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• 2014

본 논문에서는 지연시간 최소화를 위한 고속 데이터 광 전송용 ADC 개발에 관한 연구를 진행하였다. 기존 광 중계기의 전송 방식은 데이터 신호 변환에서 $6{\mu}s$이상의 지연시간을 갖고 있어 고속 데이터 전송 및 신호 변환에 제한을 받고 있으므로 이를 직접 변환 방식을 이용하여 데이터 신호 변환 시 지연시간을 $2{\mu}s$ 이내로 줄이는 새로운 기술의 개발이 요구된다. 이동통신 LTE, LTE advanced 등의 서비스 전송망 구축에 필요한 신호변환 부품 핵심기술의 발전이 요구되고 있으므로, 본 논문에서는 신호변환 단계에서 지연시간을 획기적으로 줄일 수 있는 기술을 적용하여 $3{\mu}s$의 지연시간을 갖는 ADC를 개발하였다.

• 생약학회지
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• 제29권4호
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• pp.360-364
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• 1998

To develop new elicitors inducing the high productivity of taxane derivatives, plant growth inhibitors, namely, maleic acid hydrazide, N-phosphomethyl glycine and succinic acid 2.2-dimethyl hydrazide, coconut milk and yeast extract were administrated in the cell suspension culture system of Taxus cuspidata, and the production of baccatin III were analysed. The effects of amino acid related with the biosynthesis of baccatin III were also examined in these culture system. As the results, a remarkable enhancement of baccatin III production was observed in the cultivation with coconut water and with maleic acid hydrazide.

• BMB Reports
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• 제35권6호
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• pp.537-546
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• 2002

NF-${\kappa}B$/Rel transcription factor family participates in diverse biological processes including embryo development, hematopoiesis, immune regulation, as well as neuronal functions. In this review, the NF-${\kappa}B$/Rel signal transduction pathways and their important roles in the regulation of immune system will be discussed. NF-${\kappa}B$/Rel members execute distinct functions in multiple immune cell types via the regulation of target genes essential for cell proliferation, survival, effector functions, cell trafficking and communication, as well as the formation of lymphoid architecture. Consequently, proper activation of NF-${\kappa}B$/Rel during immune responses to allergens, auto-antigens, allo-antigens, and pathogenic infection is crucial for the integrity of host innate and adaptive immunity.

• Journal of Life Science
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• 제9권2호
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• pp.34-39
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• 1999

The postsynaptic density (PSD) is a cytoskeletal specialization that is involved in the regulation of synaptic signal transduction. Mainly due to the hydrophobic nature of the PSD proteins, characterization of this intriguing structure at the molecular level has been very intractable until early 1990s. However, recent development in protein microchemistry and molecular cloning techniques allowed identification and characterization of the PSD proteins. As expected, cytoskeletal proteins constitute major components of the PSD. Other major PSD proteins have been identified by protein sequencing, and their genes were used to fish out associating proteins by yeast two-hybrid system expanding our knowledge on the molecular structure of the PSD significantly. In this review, I summarize proteins that are so far identified focusing on the glutamatergic synapses.

• BMB Reports
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• 제43권9호
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• pp.609-613
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• 2010

The Dvl and Axin proteins, which are involved in the Wnt signaling pathway, each contain a conserved DIX domain in their sequences. The DIX domain mediates interaction between Dvl and Axin, which together play an important role in signal transduction. However, the extremely low production of DIX domain fragments in E. coli has prevented more widespread functional and structural studies. In this study, we demonstrate that the DIX domains of Dvl and Axin are expressed noticeably in a multi-cistronic system but not in a mono-cistronic system. Formation of the $DIX_{Dvl1}-DIX_{Axin1}$ complex was investigated by affinity chromatography, SEC and crystallization studies. Unstable DIX domains were stabilized by complexing with counterpart DIX domains. The results of the preliminary crystallization and diffraction of the $DIX_{Dvl1}-DIX_{Axin1}$ complex may prove useful for further crystallographic studies.