• BMB Reports
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• 제33권3호
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• pp.276-278
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• 2000

The postsynaptic density (PSD), a large protein complex beneath the postsynaptic membrane, is notorious for its 'stickiness'. In order to understand the molecular composition of the PSD fraction, a 17 kDa protein band was isolated by electroelution from SDS-geis, and its partial amino acid sequence was determined from HPLC-purified tryptic peptides of the protein. Surprisingly, the amino acid sequence was identical to that of the previously reported 17 kDa isoform of the myelin basic protein (MBP), an essential protein in CNS myelin formation. Since the protein band represented ~2% of the total proteins in the 1 % n-octyl glucoside-insoluble PSD fraction, these results indicate that a significant amount of the 17 kDa isoform of MBP is tightly associated with the PSD during preparation of the PSD fraction.

• 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.

• Applied Microscopy
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• 제44권3호
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• pp.83-87
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• 2014

Electron tomography (ET) is a useful tool to investigate three-dimensional details based on virtual slices of relative thick specimen, and it requires complicated procedures consisted of image acquisition steps and image processing steps with computer program. Although the complicated step, this technique allows us to overcome some limitations of conventional transmission electron microscopy: (1) overlapping of information in the ultrathin section covering from 30 nm to 90 nm when we observe very small structures, (2) fragmentation of the information when we study larger structures over 100 nm. There are remarkable biological findings with ET, especially in the field of neuroscience, although it is not popular yet. Understanding of behavior of synaptic vesicle, active zone, pooling and fusion in the presynaptic terminal have been enhanced thanks to ET. Some sophisticated models of postsynaptic density with ET and immune labeling are introduced recently. In this review, we introduce principles, practical steps of ET and some recent researches in synapse biology.

• The Korean Journal of Physiology and Pharmacology
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• 제16권6호
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• pp.423-429
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• 2012

Brain ischemia leads to overstimulation of N-methyl-D-aspartate (NMDA) receptors, referred as excitotoxicity, which mediates neuronal cell death. However, less attention has been paid to changes in synaptic activity and morphology that could have an important impact on cell function and survival following ischemic insult. In this study, we investigated the effects of reperfusion after oxygen/glucose deprivation (OGD) not only upon neuronal cell death, but also on ultrastructural and biochemical characteristics of postsynaptic density (PSD) protein, in the stratum lucidum of the CA3 area in organotypic hippocampal slice cultures. After OGD/reperfusion, neurons were found to be damaged; the organelles such as mitochondria, endoplasmic reticulum, dendrites, and synaptic terminals were swollen; and the PSD became thicker and irregular. Ethanolic phosphotungstic acid staining showed that the density of PSD was significantly decreased, and the thickness and length of the PSD were significantly increased in the OGD/reperfusion group compared to the control. The levels of PSD proteins, including PSD-95, NMDA receptor 1, NMDA receptor 2B, and calcium/calmodulin-dependent protein kinase II, were significantly decreased following OGD/reperfusion. These results suggest that OGD/reperfusion induces significant modifications to PSDs in the CA3 area of organotypic hippocampal slice cultures, both morphologically and biochemically, and this may contribute to neuronal cell death and synaptic dysfunction after OGD/reperfusion.

• 생명과학회지
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• 제7권3호
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• pp.198-204
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• 1997

tyrosine 인산화효소계를 통한 신호전달은 신경의 발생과 연접환성조절에 중요한 역할을 한다. 흰쥐 소뇌의 연접후치밀질에 존재하는 tyrosine 함유 당백질들을 조사하기 위하여 immunoblot 분석을 한 결과, 소뇌 연접후치밀질의 전반적인 단백질조성은 전뇌와 비슷하였다. phosphotyrosine 특이성 항체로, immunobolot 한 결과 소뇌의 주된 tyrosine 인산화 단백질은 50 kD 크기의 새로운 단백질이었다. PSD-50로 명명한 이 단백질은 SDS-PAGE에서 $\alpha$CaMKII와 같은 위치에 이동하였다. 그러나 소뇌에는 전뇌에 비하여 적은량의 $\alpha$CaMKII가 존재함에도 불구하고 전뇌보다 더 강한 phosphotyrosine immunoblot signal을 보이는 것으로 보아 PSD-50는 아마도 $\alpha$CaMKII와는 다른 단백질로 추정된다.

• 생명과학회지
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• 제21권11호
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• pp.1526-1531
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• 2011

신경세포의 연접후 위치에서 단백질합성은 국소적 연접가소성의 조절에 중요한 역할을 한다. 본 연구에서는 연접후 위치에 eIF들이 존재하는지를 배양한 흰쥐해마신경세포의 면역세포화학적 염색과 immunoblot, 그리고 세제세척실험으로 알아보았다. 단백질해석 시작단계의 초기에 중요한 역할을 하는 eIF4E와 eIF4G, 개시코돈을 찾는 단계에서 중요한 eIF5, 외부자극에 의하여 합성을 시작하게 하는 eIF6, 그리고 불리한 환경에서 해석의 효율을 높여주는 eIF5A 들은 모두 해마신경세포의 연접후에 위치함을 배양한 해마신경세포를 다중초점형광현미경으로 관찰할 수 있었다. 또한 Immunoblot 실험에서도 이들은 연접후치밀질(PSD) 분획에서 검출되었으며, 여러 가지 세제에 의하여 PSD로부터 잘 떨어지지 않는 것으로 보아 PSD와 강하게 결합하고 있음을 알 수 있었다. 본 연구결과는 여러 가지 eIF들이 연접후에 위치하여 다양한 상황에서 단백질합성을 시작하게 할 수 있음을 시사한다.

• Applied Microscopy
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• 제34권4호
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• pp.223-230
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• 2004

초파리 돌연변이를 이용한 신경연접에서의 신경충격의 전달을 알아보기 위하여 배양한 초파리 배자 신경세포의 신경연접 미세구조를 관찰하여 분석하였다. 배양된 Wild-type 초파리 배자 신경세포의 신경연접(synapse)은 신경연접간극(synaptic cleft)에 의해 구분되면서 평행하게 뻗어있는 신경연접전 돌기(presynaptic area)의 세포막과 신경연접후 세포(postsynaptic cell)의 세포막 구조에 의해서 확인하였다. Presynaptic active zones과 postsynaptic densities는 각 세포막부분의 전자밀도에 의해 구분하였다. 특히 두 개의 세포막이 서로 근접하여 있으면서, 하나 또는 그 이상의 전자밀도가 높은 presynaptc densities 를 가지고 있고 그 주위에 투명한 신경연접소포들(clear core synaptic vesicles)이 모여있을 경우 이를 신경연접전 돌기로 보았다. 신경연접전 돌기에는 평균 $35.1{\pm}1.44$ nm 직경의 작고 투명한 신경연접소포들이 모여있었다. 신경연접소포들 중 일부는 세포막이나 세포막의 전자밀도가 높은 부분에 직접 접촉하고 있었는데 이를 신경전달물질이 방출되기 직전인 morphologically docked vesicles로 보았다. 이외에도 신경연접전 돌기에서는 내부가 전자밀도가 높은 물질로 채워져 있고 직경이 큰 dense core 신경연접소포들도 관찰할 수 있었다.

• 생명과학회지
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• 제12권5호
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• pp.555-560
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• 2002

연접후치밀질(PSD)의 분자조성은 아직 대체로 알려져 있지 않다. 본 연구에서는 다양한 크기의 연접후치밀질 단백질들을 효율적으로 SDS-겔에서부터 추출하는 방법을 제시하고, 이를 이용하여 연접후치밀질의 1% n-octyl glucoside에 용해되지 않는 분핵에 존재하는 31kDa크기의 단백직(PSD31로 명명)을 SDS-겔로부터 분리하고, trypsin 처리하여 생성되는 펩티드의 아미노산 서열을 결정하였다. PSD31의 아미노산 서열은 adenine nucleotide translocator 1(ANT1)과 매우 상동성이 높았다. 연접후치밀질에 ANT1이 존재함은 신경조직의 세포외 공간에 adenosine nucleotide를 유리할 수 있는 기구가 연접에 존재함을 시사한다.

• Biomolecules & Therapeutics
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• 제26권2호
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• pp.109-114
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• 2018

Liquiritigenin (LQ) is a flavonoid that can be isolated from Glycyrrhiza radix. It is frequently used as a tranditional oriental medicine herbal treatment for swelling and injury and for detoxification. However, the effects of LQ on cognitive function have not been fully explored. In this study, we evaluated the memory-enhancing effects of LQ and the underlying mechanisms with a focus on the N-methyl-D-aspartic acid receptor (NMDAR) in mice. Learning and memory ability were evaluated with the Y-maze and passive avoidance tests following administration of LQ. In addition, the expression of NMDAR subunits 1, 2A, and 2B; postsynaptic density-95 (PSD-95); phosphorylation of $Ca^{2+}$/calmodulin-dependent protein kinase II (CaMKII); phosphorylation of extracellular signal-regulated kinase 1/2 (ERK 1/2); and phosphorylation of cAMP response element binding (CREB) proteins were examined by Western blot. In vivo, we found that treatment with LQ significantly improved memory performance in both behavioral tests. In vitro, LQ significantly increased NMDARs in the hippocampus. Furthermore, LQ significantly increased PSD-95 expression as well as CaMKII, ERK, and CREB phosphorylation in the hippocampus. Taken together, our results suggest that LQ has cognition enhancing activities and that these effects are mediated, in part, by activation of the NMDAR and CREB signaling pathways.

• 동의생리병리학회지
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• 제36권1호
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• pp.18-22
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• 2022

To investigate effects of cognitive function improvement whether against Taegeuk ginseng on scopolamine-induced memory impairment in rats. All experiments were conducted in three groups: the control group (CTR), the scopolamine 0.4mg/kg (SCP), and the scopolamine (SCP+T) treated with Taegeuk ginseng 100 mg/kg. Taegeuk ginseng 100 mg/kg daily was orally administered for one month and treated with scopolamine was only for 7 consecutive days on the Morris water maze task. 3 weeks after oral administration of Taegeuk ginseng, subjects were performed the Morris water maze test for 8 days and then the open-field exploration test which to assessed for cognitive function improvement. After behavioral testing, subjects were sacrificed and microdissected brains for neurochemical analysis. In the cognitive-behavioral test, long-term administration of Taegeuk ginseng improved spatial navigation learning task compared with the impeded by scopolamine treatment. In neurochemistry, the expression of the synaptic marker PSD95 (postsynaptic density protein 95) was increased in the hippocampus compared to the scopolamine group. Also, brain-derived neurotrophic factor (BDNF) expression was significantly increased in the taegeuk ginseng administration group. These data suggested that long-term administration of taegeuk ginseng might improve cognitive-behavioral functions on hippocampal related spatial learning memory, and it was correlated with neurotropic and synaptic reinforcement. In conclusion, treatment with taegeuk ginseng may positive outcome on learning and memory deficit disorders.