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Search Results: 1 - 10 of 3274 matches for " Satoki Nakamura "
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Evaluation of the Interaction between Long Telomeric DNA and Macrocyclic Hexaoxazole (6OTD) Dimer of a G-quadruplex Ligand
Keisuke Iida,Satoki Majima,Takahiro Nakamura,Hiroyuki Seimiya,Kazuo Nagasawa
Molecules , 2013, DOI: 10.3390/molecules18044328
Abstract: Macrocyclic hexaoxazole dimer of L2H2-6OTD-dimer ( 3) was newly synthesized as a telomeric G-quadruplex (G4) ligand, and interaction with long telomeric DNAs telo48, 72, and 96 was evaluated by means of electrophoresis mobility shift assay, CD spectra analysis, and CD melting experiments. The L2H2-6OTD-dimer ( 3) interacted with the long telomeric DNAs by inducing anti-parallel type G4 structure of each unit of 24 bases, i.e., (TTAGGG) 4 sequences. Dimer 3 stabilizes long telomeric DNAs more efficiently than the corresponding monomer of L2H2-6OTD ( 2). It showed potent inhibitory activity against telomerase, with an IC 50 value of 7.5 nm.
Bcr-Abl-mediated Raf kinase inhibitor protein suppression promotes chronic myeloid leukemia progenitor cells proliferation  [PDF]
Satoki Nakamura, Tomohiro Yagyu, Tomonari Takemura, Lin Tan, Yasuyuki Nagata, Daisuke Yokota, Isao Hirano, Kiyoshi Shibata, Michio Fujie, Shinya Fujisawa, Kazunori Ohnishi
Stem Cell Discovery (SCD) , 2011, DOI: 10.4236/scd.2011.13006
Abstract: The Ras/Raf-1/MEK/ERK pathway is constitutively activated in Bcr-Abl transformed cells, and Ras activity enhances the oncogenic ability of Bcr-Abl. On the hand, Raf kinase inhibitor protein (RKIP) inhibits activation of MEK by Raf-1 and its downstream signal transduction, resulting in blocking the MAP kinase pathway. Moreover, Raf-1 has been reported to regulate cell cycle progression. However, the mechanism by which Bcr-Abl promotes the cell cycle progression through Raf-1 is not completely understood. In the present study, we found that the expression of RKIP was suppressed in CML cells, and investigated the interaction between RKIP and Bcr-Abl in CML cells. In aldehyde dehydrogenase (ALDH)hi/CD34+ cells derived from CML patients, the inhibition of Bcr-Abl induced RKIP expression and reduced the phosphorylated-FOXM1 (pFOXM1) status, resulting in inhibited colony formation of Bcr-Abl+ progenitor cells. Moreover, overexpression of RKIP significantly decreased the colony numbers, reduced the pFOXM1 status, and reduced pFOXM-1 target genes such as Skp2, Cdc25B and KIS, and induced the expression of p27Kip1a and p21Cip1. Thus, Bcr-Abl represses the expression of RKIP, and continuously activates FOXM1, resulting in the proliferation of CML progenitor cells through the cell cycle modulation.
Selective Heating of Transition Metal Usings Hydrogen Plasma and Its Application to Formation of Nickel Silicide Electrodes for Silicon Ultralarge-Scale Integration Devices  [PDF]
Tetsuji Arai, Hiroki Nakaie, Kazuki Kamimura, Hiroyuki Nakamura, Satoshi Ariizumi, Satoki Ashizawa, Keisuke Arimoto, Junji Yamanaka, Tetsuya Sato, Kiyokazu Nakagawa, Toshiyuki Takamatsu
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.41006
Abstract:

We developed an apparatus for producing high-density hydrogen plasma. The atomic hydrogen density was 3.1 × 1021 m?3 at a pressure of 30 Pa, a microwave power of 1000 W, and a hydrogen gas flow rate of 10 sccm. We confirmed that the temperatures of transition-metal films increased to above 800C within 5 s when they were exposed to hydrogen plasma formed using the apparatus. We applied this phenomenon to the selective heat treatment of nickel films deposited on silicon wafers and formed nickel silicide electrodes. We found that this heat phenomenon automatically stopped after the nickel slicidation reaction finished. To utilize this method, we can perform the nickel silicidation process without heating the other areas such as channel regions and improve the reliability of silicon ultralarge-scale integration devices.

GSK3 regulates the expressions of human and mouse c-Myb via different mechanisms
Kyoko Kitagawa, Yojiro Kotake, Yoshihiro Hiramatsu, Ning Liu, Sayuri Suzuki, Satoki Nakamura, Akira Kikuchi, Masatoshi Kitagawa
Cell Division , 2010, DOI: 10.1186/1747-1028-5-27
Abstract: Human c-Myb was degraded by ubiquitin-dependent degradation via SCF-Fbw7. Human Fbw7 ubiquitylated not only human c-Myb but also mouse c-Myb, whereas mouse Fbw7 ubiquitylated mouse c-Myb but not human c-Myb. Human Fbw7 mutants with mutations of arginine residues important for recognition of the CPD still ubiquitylated human c-Myb. These data strongly suggest that human Fbw7 ubiquitylates human c-Myb in a CPD-independent manner. Mutations of the putative GSK3 phosphorylation sites in human c-Myb did not affect the Fbw7-dependent ubiquitylation of human c-Myb. Neither chemical inhibitors nor a siRNA for GSK3β affected the stability of human c-Myb. However, depletion of GSK3β upregulated the transcription of human c-Myb, resulting in transcriptional suppression of γ-globin, one of the c-Myb target genes.The present observations suggest that human Fbw7 ubiquitylates human c-Myb in a CPD-independent manner, whereas mouse Fbw7 ubiquitylates human c-Myb in a CPD-dependent manner. Moreover, GSK3 negatively regulates the transcriptional expression of human c-Myb but does not promote Fbw7-dependent degradation of human c-Myb protein. Inactivation of GSK3 as well as mutations of Fbw7 may be causes of the enhanced c-Myb expression observed in leukemia cells. We conclude that expression levels of human and mouse c-Myb are regulated via different mechanisms.The leucine zipper transcription factor c-Myb is expressed at high levels in immature progenitors of all the hematopoietic lineages, and is essential for fetal liver hematopoiesis, erythroid and myeloid bone marrow colony formation, and T- and B-cell development [1-4]. Moreover, elevated c-Myb expression is associated with hematological malignancies and has been reported in many cases of acute myeloblastic and lymphoblastic leukemias [1,5-7]. The keys to the control of c-Myb protein function are post-transcriptional modifications. The c-Myb protein is phosphorylated by several kinases such as MAPK, Nemo-like kinase (NLK) and g
Discovery of an Outstanding Disk in the cD Galaxy of the Hydra A Cluster
Yutaka Fujita,Nobuhiro Okabe,Kosuke Sato,Takayuki Tamura,Satoki Matsushita,Hiroyuki Hirashita,Masanori Nakamura,Kyoko Matsushita,Kazuhiro Nakazawa,Motokazu Takizawa
Physics , 2013, DOI: 10.1093/pasj/65.6.L15
Abstract: The central cD galaxy of the Hydra A cluster has one of the most powerful active galactic nuclei (AGNs) in the nearby Universe (z <0.2). We report on the discovery of a dust lane in the cD galaxy using Subaru telescope. The i'-band image shows the existence of a dark band of the size of 3.6"x 0.7" (4 kpc x 0.8 kpc), which appears to be quite similar to the dust lane observed in Centaurus A. The morphology indicates that the cold disk that seen as the dust lane is almost edge-on and rotates around the AGN. Since the minor axis of the dust lane is nearly parallel to the radio jets emerging from the AGN, the disk is probably feeding its gas into the central black hole. From the absorption, we estimate the hydrogen column density of the lane is N_H=2.0 x 10^21 cm^-2, and the mass of the disk is ~8 x 10^7 M_sun. The column density is consistent with constraints obtained from Chandra X-ray observations. The age of the disk is >~ 4 x 10^7 yr. The position angle of the disk and the galaxy's photometric axis are misaligned, which may imply that the cold gas in the disk is brought via galaxy mergers. Our observations may indicate that the supply of cold gas by galaxy mergers is required for the most intensive feedback from AGNs.
10 pc Scale Circumnuclear Molecular Gas Imaging of Nearby AGNs
Satoki Matsushita
Physics , 2012, DOI: 10.1088/1742-6596/372/1/012043
Abstract: We present the images and kinematics of circumnuclear molecular gas from 100 pc scale down to 10 pc scale in nearby active galactic nuclei (AGNs) using the Submillimeter Array (SMA) and the Plateau de Bure Interferometer (PdBI). We have observed several nearby galaxies that host AGNs, such as the nearest radio galaxy Centaurus A (NGC 5128), the Seyfert 2 galaxy M51 (NGC 5194), the Seyfert 2 galaxy NGC 1068, the Seyfert 1 galaxy NGC 1097, and the Seyfert 2 / starburst composite galaxy NGC 4945, in CO lines to see whether the molecular gas distribution, kinematics, and physical conditions at 10 - 100 pc scale follows the AGN unified model or not. In 100 pc scale, most of the circumnuclear molecular gas shows smooth velocity gradient, suggesting a regular rotating feature, and also shows abnormal line ratios, suggesting the existence of active sources to make the circumnuclear molecular gas dense and/or warm conditions or abnormal chemical compositions. In 10 pc scale, on the other hand, the molecular gas kinematics shows various characteristics, some shows very disturbed kinematics such as a jet-entrained feature in the galaxies that have jets, but some still shows regular rotation feature in a galaxy that does not have obvious jets. These results indicate that the kinematics and physical/chemical conditions of the circumnuclear molecular gas at the scale less than 100 pc is highly affected by the AGN activities, and at this scale, there is no clear evidence of any unified feature seen in the circumnuclear molecular gas.
Possibility of Terahertz Observations at the ALMA site
Satoki Matsushita
Physics , 2011,
Abstract: Observational rates under terahertz (THz) opacities less than 3.0 and 2.0 at the Atacama Large Millimeter/submillimeter Array (ALMA) site have been calculated using the 225 GHz tipping radiometer monitoring data and the opacity correlation between 225 GHz and THz opacities. The observational rate with THz opacity condition less than 3.0 is 12.4% in a year, and in winter (November - April) it is about twice higher than in summer (May - October). This observational rate shows a large sinusoidal annual variation, and it seems to have relation with the El Ni\~no and La Ni\~na phenomena; the La Ni\~na years tend to have high observational rates, but the El Ni\~no years show low rates. On the other hand, the observational rate with the THz opacity condition less than 2.0 is only 1.9%, and no obvious annual and seasonal variations are observed. This indicates that THz observations under low opacity condition of less than 2.0 at the ALMA site are very difficult to be performed.
The CRKL gene encoding an adaptor protein is amplified, overexpressed, and a possible therapeutic target in gastric cancer
Hiroko Natsume, Kazuya Shinmura, Hong Tao, Hisaki Igarashi, Masaya Suzuki, Kiyoko Nagura, Masanori Goto, Hidetaka Yamada, Matsuyoshi Maeda, Hiroyuki Konno, Satoki Nakamura, Haruhiko Sugimura
Journal of Translational Medicine , 2012, DOI: 10.1186/1479-5876-10-97
Abstract: A genome-wide single nucleotide polymorphism microarray analysis was performed using three cell lines of differentiated gastric cancers, and 22 genes (including ERBB2) in five highly amplified chromosome regions (with a copy number of more than 6) were identified. Particular attention was paid to the CRKL gene, the product of which is an adaptor protein containing Src homology 2 and 3 (SH2/SH3) domains. An extremely high CRKL copy number was confirmed in the MKN74 gastric cancer cell line using fluorescence in situ hybridization (FISH), and a high level of CRKL expression was also observed in the cells. The RNA-interference-mediated knockdown of CRKL in MKN74 disclosed the ability of CRKL to upregulate gastric cell proliferation. An immunohistochemical analysis revealed that CRKL protein was overexpressed in 24.4% (88/360) of the primary gastric cancers that were analyzed. The CRKL copy number was also examined in 360 primary gastric cancers using a FISH analysis, and CRKL amplification was found to be associated with CRKL overexpression. Finally, we showed that MKN74 cells with CRKL amplification were responsive to the dual Src/BCR-ABL kinase inhibitor BMS354825, likely via the inhibition of CRKL phosphorylation, and that the proliferation of MKN74 cells was suppressed by treatment with a CRKL-targeting peptide.These results suggested that CRKL protein is overexpressed in a subset of gastric cancers and is associated with CRKL amplification in gastric cancer. Furthermore, our results suggested that CRKL protein has the ability to regulate gastric cell proliferation and has the potential to serve as a molecular therapy target for gastric cancer.Although the overall incidence of gastric cancer is decreasing in many countries, the high incidence of gastric cancer remains a serious health problem, and gastric cancer continues to be the second-leading cause of cancer-related death worldwide [1,2]. Gastric carcinogenesis is a multi-step process in which environmental and
FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola III. Water Vapor, Liquid Water, and 183 GHz Water Vapor Line Opacities
Satoki Matsushita,Hiroshi Matsuo
Physics , 2003, DOI: 10.1093/pasj/55.1.325
Abstract: Further analysis has been made on the millimeter and submillimeter-wave (100-1600 GHz or 3 mm - 188 micron) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows good correlation with the 183 GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183 GHz line opacity show no correlation. Since only the water vapor component is expected to affect the phase of interferometers significantly, and the submillimeter-wave opacity is less affected by the liquid water component, it may be possible to use the submillimeter-wave opacity for a phase-correction of submillimeter interferometers.
Transcriptional Repression of Cdc25B by IER5 Inhibits the Proliferation of Leukemic Progenitor Cells through NF-YB and p300 in Acute Myeloid Leukemia
Satoki Nakamura, Yasuyuki Nagata, Lin Tan, Tomonari Takemura, Kiyoshi Shibata, Michio Fujie, Shinya Fujisawa, Yasutaka Tanaka, Mitsuo Toda, Reiko Makita, Kenji Tsunekawa, Manabu Yamada, Mayumi Yamaoka, Junko Yamashita, Kazunori Ohnishi, Mitsuji Yamashita
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028011
Abstract: The immediately-early response gene 5 (IER5) has been reported to be induced by γ-ray irradiation and to play a role in the induction of cell death caused by radiation. We previously identified IER5 as one of the 2,3,4-tribromo-3-methyl-1-phenylphosphol?ane1-oxide (TMPP)-induced transcriptional responses in AML cells, using microarrays that encompassed the entire human genome. However, the biochemical pathway and mechanisms of IER5 function in regulation of the cell cycle remain unclear. In this study, we investigated the involvement of IER5 in the cell cycle and in cell proliferation of acute myeloid leukemia (AML) cells. We found that the over-expression of IER5 in AML cell lines and in AML-derived ALDHhi (High Aldehyde Dehydrogenase activity)/CD34+ cells inhibited their proliferation compared to control cells, through induction of G2/M cell cycle arrest and a decrease in Cdc25B expression. Moreover, the over-expression of IER5 reduced colony formation of AML-derived ALDHhi/CD34+ cells due to a decrease in Cdc25B expression. In addition, over-expression of Cdc25B restored TMPP inhibitory effects on colony formation in IER5-suppressed AML-derived ALDHhi/CD34+ cells. Furthermore, the IER5 reduced Cdc25B mRNA expression through direct binding to Cdc25B promoter and mediated its transcriptional attenuation through NF-YB and p300 transcriptinal factors. In summary, we found that transcriptional repression mediated by IER5 regulates Cdc25B expression levels via the release of NF-YB and p300 in AML-derived ALDHhi/CD34+ cells, resulting in inhibition of AML progenitor cell proliferation through modulation of cell cycle. Thus, the induction of IER5 expression represents an attractive target for AML therapy.
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