• Biomolecules & Therapeutics
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• v.24 no.2
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• pp.115-122
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• 2016

Sleep, which is an essential part of human life, is modulated by neurotransmitter systems, including gamma-aminobutyric acid (GABA) and dopamine signaling. However, the mechanisms that initiate and maintain sleep remain obscure. In this study, we investigated the relationship between melatonin (MT) and dopamine D2-like receptor signaling in pentobarbital-induced sleep and the intracellular mechanisms of sleep maintenance in the cerebral cortex. In mice, pentobarbital-induced sleep was augmented by intraperitoneal administration of 30 mg/kg MT. To investigate the relationship between MT and D2-like receptors, we administered quinpirole, a D2-like receptor agonist, to MT- and pentobarbital-treated mice. Quinpirole (1 mg/kg, i.p.) increased the duration of MT-augmented sleep in mice. In addition, locomotor activity analysis showed that neither MT nor quinpirole produced sedative effects when administered alone. In order to understand the mechanisms underlying quinpirole-augmented sleep, we measured protein levels of mitogen-activated protein kinases (MAPKs) and cortical protein kinases related to MT signaling. Treatment with quinpirole or MT activated extracellular-signal-regulated kinase 1 and 2 (ERK1/2), p38 MAPK, and protein kinase C (PKC) in the cerebral cortex, while protein kinase A (PKA) activation was not altered significantly. Taken together, our results show that quinpirole increases the duration of MT-augmented sleep through ERK1/2, p38 MAPK, and PKC signaling. These findings suggest that modulation of D2-like receptors might enhance the effect of MT on sleep.

• Proceedings of the PSK Conference
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• 2000.10a
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• pp.147.2-148
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• 2000

• Animal cells and systems
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• v.11 no.2
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• pp.205-213
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• 2007

Nek6 belongs to NIMA1 (never in mitosis, gene A) related kinase, which was originally identified in Aspergillus nidulans as a serine/threonine kinase critical for cell cycle progression. We noticed that the putative SUMOylation site is localized on the $K^{252}$ residue in $^{251}FKsD^{254}$ of Nek6, based on the consensus sequence ${\Phi}KxE$; where ${\Phi}$ represents L, I, V or F and x is any amino acid. We observed that the Nek6 SUMO mutant (K252R) has decreased protein kinase activity, nuclear speckle localization and protein stability, compared with that of the Nek6 wild type. However, the Nek6 SUMO mutant increased the cell survival rate of COS-1 cells as determined by FACS analysis. Therefore, our data suggest that SUMOylation on the $K^{252}$ residue of Nek6 is required for its normal functions, such as proper nuclear localization, kinase activity and protein stability, to control cell cycle.

• Applied Biological Chemistry
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• v.43 no.3
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• pp.174-178
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• 2000

To search CDK4/Cyclin D1 enzyme inhibition materials, methanol extracts of native eighty seven plant species in thirty seven families were screened in vitro for their inhibiting activities against CDK4/Cyclin D1 enzyme which are control to the normal cell division cycle in human body. Extracts of Paeonia suffruticosa, Saurus chinensis, Sanguisorba officinalis and Celastrus orbiculatus among them significantly inhibited above fifty percent $(in\;5\;{\mu}g/ml)$ against CDK4/ Cyclin D1 enzyme. Especially, the extracts of P. suffruticosa and S. officinalis showed moderately strong inhibition. Also, cryptotanshinone was identified as active compound from a extracts of Salvia mitiorrhiza by spectroscopic analyses including 2D NMR experiments.

• BMB Reports
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• v.42 no.8
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• pp.516-522
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• 2009

SH2D4A, comprising a single SH2 domain, is a novel protein of the SH2 signaling protein family. We have previously demonstrated SH2D4A is expressed ubiquitously in various tissues and is located in the cytoplasm. In this study we investigated the function of SH2D4A in human embryonic kidney (HEK) 293 cells using interaction analysis, cell proliferation assays, and kinase activity detection. SH2D4A was found to directly bind to estrogen receptor $\alpha$ (ER$\alpha$), and prevent the recruitment of phospholipase C-$\gamma$ (PLC-$\gamma$) to ER$\alpha$. Moreover, we observed its inhibitory effects on estrogen-induced cell proliferation, involving the protein kinase C (PKC) signaling pathway. Together, these findings suggested that SH2D4A inhibited cell proliferation by suppression of the ER$\alpha$/PLC-$\gamma$/PKC signaling pathway. SH2D4A may be useful for the development of a new anti-cancer drug acting as an ER signaling modulator.

• BMB Reports
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• v.39 no.6
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• pp.774-781
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• 2006

Human nucleolar phosphoprotein p140 (hNopp140) is a nucleolar phosphoprotein that can bind to doxorubicin, an anti-cancer agent. We have examined the interaction between hNopp140 and doxorubicin as well as the folding property of hNopp140. Also, the effects of ATP and phosphorylation on the affinity of hNopp140 to doxorubicin are investigated by affinity dependent co-precipitation and surface plasmon resonance methods. Doxorubicin preferentially binds to un-phosphorylated form of hNopp140 with a $K_D$ value of $3.3\;{\times}\;10^{-7}$ M. Furthermore, doxorubicin reduces the protein kinase CK2-dependent phosphorylation of hNopp140, indicating that doxorubicin may perturb the cellular function of hNopp140 by reducing the protein kinase CK2-dependent phosphorylation of hNopp140. Low contents of the secondary structures of hNopp140 and the fast rate of proteolysis imply that hNopp140 has a high percentage of flexible regions or extended loop structures.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1115-1122
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• 2021

Rotavirus (RV), as the main cause of diarrhea in children under 5 years, contributes to various childhood diseases. Valeriana jatamansi Jones is a traditional Chinese herb and possesses antiviral effects. In this study we investigated the potential mechanisms of V. jatamansi Jones in RV-induced diarrhea. MTT assay was performed to evaluate cell proliferation and the diarrhea mice model was constructed using SA11 infection. Mice were administered V. jatamansi Jones and ribavirin. Diarrhea score was used to evaluate the treatment effect. The enzyme-linked immunosorbent assay was performed to detect the level of cytokines. Western blot and quantitative reverse transcription-PCR were used to determine protein and mRNA levels, respectively. Hematoxylin-eosin staining was applied to detect the pathological change of the small intestine. TdT-mediated dUTP nick-end labeling was conducted to determine the apoptosis rate. The results showed V. jatamansi Jones promoted MA104 proliferation. V. jatamansi Jones downregulated phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) in protein level, which was consistent with the immunohistochemistry results. Moreover, V. jatamansi Jones combined with ribavirin regulated interleukin-1β (IL-1β), interferon γ, IL-6, tumor necrosis factor α, and IL-10, and suppressed secretory immunoglobulin A secretion to remove viruses and inhibit dehydration. V. jatamansi Jones + ribavirin facilitated the apoptosis of small intestine cells. In conclusion, V. jatamansi Jones may inhibit RV-induced diarrhea through PI3K/AKT signaling pathway, and could therefore be a potential therapy for diarrhea.

• BMB Reports
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• v.43 no.4
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• pp.263-267
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• 2010

To characterize the biochemical properties of the PP2A regulatory B subunit, PPP2R5D, we analyzed its phosphorylation sites, stoichiometry and effect on holoenzyme activity. PPP2R5D was phosphorylated on Ser-53, Ser-68, Ser-81, and Ser-566 by protein kinase A, and mutations at all four of these sites abolished any significant phosphorylation in vitro. In HEK293 cells, however, the Ser-566 was the major phosphorylation site after PKA activation by forskolin, with marginal phosphorylation on Ser-81. Inhibitory tyrosine phosphorylation on Tyr-307 of the PP2A catalytic C subunit was decreased after forskolin treatment. Kinetic analysis showed that overall PP2A activity was increased with phosphorylation by PPP2R5D phosphorylation. The apparent Km was reduced from $11.25\;{\mu}M$ to $1.175\;{\mu}M$ with PPP2R5D phosphorylation, resulting in an increase in catalytic activity. These data suggest that PKA-mediated activation of PP2A is enabled by PPP2R5D phosphorylation, which modulates the affinity of the PP2A holoenzyme to its physiological substrates.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.1
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• pp.1-10
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• 2012

A new scalaran class sesterterpenoid with five known ones was isolated from a marine sponge Smenospongia species collected from the Gageo island, Korea. Chemical structure of all of compounds was determined on the basis of a combination of extensive 1D and 2D NMR experiments and MS data. The new compound exhibited a new functional group on a common scalaran sesterterpene skeleton, identified as 12-deacetoxy-23-deacetoxyscalarin. The compound 1 moderately showed the effect of the activation of AMP-activated protein kinase (AMPK) in L6 myoblast cell.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.135-135
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• 1993

신호전달과정에 중요한 역할을 하고 있는 다기능 serinei/threonine 단백질인산화효소인 protein kinase C(PKC)의 연구를 위해 이 효소의 정제를 뇌에서 착수하였다 PKC의 활성측정을 myelin basic protein을 기질로 하여 20 mM Tris 완충용액 PH 7.5, 0.15 mM [${\gamma}$-$^{32}$P]ATP(3 $\times$ $10^{5}$ cpm), 0.1 mM $Ca^{2＋}$, 10$\mu\textrm{g}$ phosphatidylserine과 2$\mu\textrm{g}$ diolein을 넣어 반응시켰다. 반응은 TCA로 정지시킨 후 방사성 단백질을 Millipore filter paper로 걸러 섬광 계수기로 읽었다. Cytosol PKC의 정제과정은 첫 단계에서 DEAE-cellulose를 사용하였으며, phenyl sepharose CL-4B와 protamine agarose를 연속적으로 이용하여 800배의 정제에 성공했다. SDS-PACE 상에서 80 kD로 나타났으며 순도는 95 % 이상이였다. 이를 이용 PKC의 각종 기질 연구에 착수하기 시작했으며, 이중 MBP의 인산화연구를 통한 myelin의 안정성과 MBP와의 구조 관계가 일부 수행되고 있다 연차적으로 PKC와 이와 관련된 단백질의 특성을 살피기 위해 뇌의 PKC 기질 중 cold stress를 통해 환경에 민감한 것을 찾고 있으며, 현재 autoradiography를 이용해 80 kD, 54 kD, 49 kD와 35 kD의 단백질이 연구대상이 되고있다. 그 중 49 kD는 B-50(또는 GAP43, neuromodulin이라고도 함)일 가능성이 높아 이 단백질 조절과 PKC 활성화 사이의 관계 정립이 흥미로운 과제로 대두되고 있다.다.