1
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Mizumoto A, Yokoyama Y, Miyoshi T, Takikawa M, Ishikawa F, Sadaie M. DHX36 maintains genomic integrity by unwinding G-quadruplexes. Genes Cells 2023; 28:694-708. [PMID: 37632696 DOI: 10.1111/gtc.13061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/08/2023] [Accepted: 08/12/2023] [Indexed: 08/28/2023]
Abstract
The guanine-rich stretch of single-stranded DNA (ssDNA) forms a G-quadruplex (G4) in a fraction of genic and intergenic chromosomal regions. The probability of G4 formation increases during events causing ssDNA generation, such as transcription and replication. In turn, G4 abrogates these events, leading to DNA damage. DHX36 unwinds G4-DNA in vitro and in human cells. However, its spatial correlation with G4-DNA in vivo and its role in genome maintenance remain unclear. Here, we demonstrate a connection between DHX36 and G4-DNA and its implications for genomic integrity. The nuclear localization of DHX36 overlapped with that of G4-DNA, RNA polymerase II, and a splicing-related factor. Depletion of DHX36 resulted in accumulated DNA damage, slower cell growth, and enhanced cell growth inhibition upon treatment with a G4-stabilizing compound; DHX36 expression reversed these defects. In contrast, the reversal upon expression of DHX36 mutants that could not bind G4 was imperfect. Thus, DHX36 may suppress DNA damage by promoting the clearance of G4-DNA for cell growth and survival. Our findings deepen the understanding of G4 resolution in the maintenance of genomic integrity.
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Affiliation(s)
- Ayaka Mizumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Department of Therapeutic Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuta Yokoyama
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Tomoichiro Miyoshi
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Laboratory for Retrotransposon Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Masahiro Takikawa
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Mahito Sadaie
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
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2
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Hara T, Nakaoka H, Miyoshi T, Ishikawa F. The CST complex facilitates cell survival under oxidative genotoxic stress. PLoS One 2023; 18:e0289304. [PMID: 37590191 PMCID: PMC10434909 DOI: 10.1371/journal.pone.0289304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/15/2023] [Indexed: 08/19/2023] Open
Abstract
Genomic DNA is constantly exposed to a variety of genotoxic stresses, and it is crucial for organisms to be equipped with mechanisms for repairing the damaged genome. Previously, it was demonstrated that the mammalian CST (CTC1-STN1-TEN1) complex, which was originally identified as a single-stranded DNA-binding trimeric protein complex essential for telomere maintenance, is required for survival in response to hydroxyurea (HU), which induces DNA replication fork stalling. It is still unclear, however, how the CST complex is involved in the repair of diverse types of DNA damage induced by oxidizing agents such as H2O2. STN1 knockdown (KD) sensitized HeLa cells to high doses of H2O2. While H2O2 induced DNA strand breaks throughout the cell cycle, STN1 KD cells were as resistant as control cells to H2O2 treatment when challenged in the G1 phase of the cell cycle, but they were sensitive when exposed to H2O2 in S/G2/M phase. STN1 KD cells showed a failure of DNA synthesis and RAD51 foci formation upon H2O2 treatment. Chemical inhibition of RAD51 in shSTN1 cells did not exacerbate the sensitivity to H2O2, implying that the CST complex and RAD51 act in the same pathway. Collectively, our results suggest that the CST complex is required for maintaining genomic stability in response to oxidative DNA damage, possibly through RAD51-dependent DNA repair/protection mechanisms.
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Affiliation(s)
- Tomohiko Hara
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Hidenori Nakaoka
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Tomoicihiro Miyoshi
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Laboratory for Retrotransposon Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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3
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Jansson M, Nosenko VV, Rudko GY, Ishikawa F, Chen WM, Buyanova IA. Lattice dynamics and carrier recombination in GaAs/GaAsBi nanowires. Sci Rep 2023; 13:12880. [PMID: 37553456 PMCID: PMC10409742 DOI: 10.1038/s41598-023-40217-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/07/2023] [Indexed: 08/10/2023] Open
Abstract
GaAsBi nanowires represent a novel and promising material platform for future nano-photonics. However, the growth of high-quality GaAsBi nanowires and GaAsBi alloy is still a challenge due to a large miscibility gap between GaAs and GaBi. In this work we investigate effects of Bi incorporation on lattice dynamics and carrier recombination processes in GaAs/GaAsBi core/shell nanowires grown by molecular-beam epitaxy. By employing photoluminescence (PL), PL excitation, and Raman scattering spectroscopies complemented by scanning electron microscopy, we show that increasing Bi-beam equivalent pressure (BEP) during the growth does not necessarily result in a higher alloy composition but largely affects the carrier localization in GaAsBi. Specifically, it is found that under high BEP, bismuth tends either to be expelled from a nanowire shell towards its surface or to form larger clusters within the GaAsBi shell. Due to these two processes the bandgap of the Bi-containing shell remains practically independent of the Bi BEP, while the emission spectra of the NWs experience a significant red shift under increased Bi supply as a result of the localization effect.
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Affiliation(s)
- M Jansson
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden
| | - V V Nosenko
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden.
| | - G Yu Rudko
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden
| | - F Ishikawa
- Research Center for Integrated Quantum Electronics, Hokkaido University, Sapporo, 060-8628, Japan
| | - W M Chen
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden
| | - I A Buyanova
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden.
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Luqman-Fatah A, Watanabe Y, Uno K, Ishikawa F, Moran JV, Miyoshi T. Author Correction: The interferon stimulated gene-encoded protein HELZ2 inhibits human LINE-1 retrotransposition and LINE-1 RNA-mediated type I interferon induction. Nat Commun 2023; 14:493. [PMID: 36717557 PMCID: PMC9886985 DOI: 10.1038/s41467-023-36226-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Ahmad Luqman-Fatah
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan.,Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Yuzo Watanabe
- Proteomics Facility, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Kazuko Uno
- Division of Basic Research, Louis Pasteur Center for Medical Research, Kyoto, 606-8225, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan.,Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - John V Moran
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA.,Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Tomoichiro Miyoshi
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan. .,Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan. .,Laboratory for Retrotransposon Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, 230-0045, Japan.
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5
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Luqman-Fatah A, Watanabe Y, Uno K, Ishikawa F, Moran JV, Miyoshi T. The interferon stimulated gene-encoded protein HELZ2 inhibits human LINE-1 retrotransposition and LINE-1 RNA-mediated type I interferon induction. Nat Commun 2023; 14:203. [PMID: 36639706 PMCID: PMC9839780 DOI: 10.1038/s41467-022-35757-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 12/23/2022] [Indexed: 01/15/2023] Open
Abstract
Some interferon stimulated genes (ISGs) encode proteins that inhibit LINE-1 (L1) retrotransposition. Here, we use immunoprecipitation followed by liquid chromatography-tandem mass spectrometry to identify proteins that associate with the L1 ORF1-encoded protein (ORF1p) in ribonucleoprotein particles. Three ISG proteins that interact with ORF1p inhibit retrotransposition: HECT and RLD domain containing E3 ubiquitin-protein ligase 5 (HERC5); 2'-5'-oligoadenylate synthetase-like (OASL); and helicase with zinc finger 2 (HELZ2). HERC5 destabilizes ORF1p, but does not affect its cellular localization. OASL impairs ORF1p cytoplasmic foci formation. HELZ2 recognizes sequences and/or structures within the L1 5'UTR to reduce L1 RNA, ORF1p, and ORF1p cytoplasmic foci levels. Overexpression of WT or reverse transcriptase-deficient L1s lead to a modest induction of IFN-α expression, which is abrogated upon HELZ2 overexpression. Notably, IFN-α expression is enhanced upon overexpression of an ORF1p RNA binding mutant, suggesting ORF1p binding might protect L1 RNA from "triggering" IFN-α induction. Thus, ISG proteins can inhibit retrotransposition by different mechanisms.
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Affiliation(s)
- Ahmad Luqman-Fatah
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Yuzo Watanabe
- Proteomics Facility, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Kazuko Uno
- Division of Basic Research, Louis Pasteur Center for Medical Research, Kyoto, 606-8225, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - John V Moran
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Tomoichiro Miyoshi
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan.
- Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan.
- Laboratory for Retrotransposon Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, 230-0045, Japan.
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6
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Yamamoto I, Nakaoka H, Takikawa M, Tashiro S, Kanoh J, Miyoshi T, Ishikawa F. Fission yeast Stn1 maintains stability of repetitive DNA at subtelomere and ribosomal DNA regions. Nucleic Acids Res 2021; 49:10465-10476. [PMID: 34520548 PMCID: PMC8501966 DOI: 10.1093/nar/gkab767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 08/03/2021] [Accepted: 08/31/2021] [Indexed: 11/14/2022] Open
Abstract
Telomere binding protein Stn1 forms the CST (Cdc13/CTC1-STN1-TEN1) complex in budding yeast and mammals. Likewise, fission yeast Stn1 and Ten1 form a complex indispensable for telomere protection. We have previously reported that stn1-1, a high-temperature sensitive mutant, rapidly loses telomere DNA at the restrictive temperature due to frequent failure of replication fork progression at telomeres and subtelomeres, both containing repetitive sequences. It is unclear, however, whether Stn1 is required for maintaining other repetitive DNAs such as ribosomal DNA. In this study, we have demonstrated that stn1-1 cells, even when grown at the permissive temperature, exhibited dynamic rearrangements in the telomere-proximal regions of subtelomere and ribosomal DNA repeats. Furthermore, Rad52 and γH2A accumulation was observed at ribosomal DNA repeats in the stn1-1 mutant. The phenotypes exhibited by the stn1-1 allele were largely suppressed in the absence of Reb1, a replication fork barrier-forming protein, suggesting that Stn1 is involved in the maintenance of the arrested replication forks. Collectively, we propose that Stn1 maintains the stability of repetitive DNAs at subtelomeres and rDNA regions.
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Affiliation(s)
- Io Yamamoto
- Laboratory of Cell Cycle Regulation, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan.,Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan
| | - Hidenori Nakaoka
- Laboratory of Cell Cycle Regulation, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan.,Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan
| | - Masahiro Takikawa
- Laboratory of Cell Cycle Regulation, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan
| | - Sanki Tashiro
- Laboratory of Cell Cycle Regulation, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan.,Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Junko Kanoh
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan.,Department of Life Sciences, Graduate School of Arts and Sciences, the University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Tomoichiro Miyoshi
- Laboratory of Cell Cycle Regulation, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan.,Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan
| | - Fuyuki Ishikawa
- Laboratory of Cell Cycle Regulation, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan.,Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8501, Japan
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7
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Yukimune M, Fujiwara R, Mita T, Ishikawa F. Polytypism in GaAs/GaNAs core-shell nanowires. Nanotechnology 2020; 31:505608. [PMID: 32937605 DOI: 10.1088/1361-6528/abb904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report the crystal structures of GaAs and GaAs/GaNAs/GaAs core-multishell nanowires (NWs). From statistical investigations by x-ray diffraction (XRD) and electron backscattered diffraction (EBSD) pattern analysis, we statistically and microscopically resolve the zinc-blende (ZB) and wurtzite (WZ) polytypism within the NWs. The XRD analysis shows a smaller fraction of WZ segments in the NWs with a larger concentration of nitrogen. With increasing nitrogen content in the GaNAs shell, the ZB peak position shifts toward higher angles and the WZ peak intensity decreases. The EBSD measurements also confirm the coexistence of ZB and WZ polytypes in all of the NWs. Their polytype switches along the length. Twin defects are observed in the ZB segments in all of the NWs. The unique grain map and grain size distribution show a decrease of the WZ segments in the GaAs/GaNAs/GaAs NW, in agreement with the XRD results. Microscopically, the local area where the polytype switches from WZ in the inner-core side to ZB toward the outer-shell surface is observed. Overall, we propose that the WZ polytype in the GaAs NWs decreases because of the strain induced by the growth of the GaNAs shell with a smaller lattice constant.
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Affiliation(s)
- M Yukimune
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - R Fujiwara
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - T Mita
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - F Ishikawa
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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8
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Kagaya K, Noma-Takayasu N, Yamamoto I, Tashiro S, Ishikawa F, Hayashi MT. Chromosome instability induced by a single defined sister chromatid fusion. Life Sci Alliance 2020; 3:e202000911. [PMID: 33106324 PMCID: PMC7652394 DOI: 10.26508/lsa.202000911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 12/13/2022] Open
Abstract
Chromosome fusion is a frequent intermediate in oncogenic chromosome rearrangements and has been proposed to cause multiple tumor-driving abnormalities. In conventional experimental systems, however, these abnormalities were often induced by randomly induced chromosome fusions involving multiple different chromosomes. It was therefore not well understood whether a single defined type of chromosome fusion, which is reminiscent of a sporadic fusion in tumor cells, has the potential to cause chromosome instabilities. Here, we developed a human cell-based sister chromatid fusion visualization system (FuVis), in which a single defined sister chromatid fusion is induced by CRISPR/Cas9 concomitantly with mCitrine expression. The fused chromosome subsequently developed extra-acentric chromosomes, including chromosome scattering, indicative of chromothripsis. Live-cell imaging and statistical modeling indicated that sister chromatid fusion generated micronuclei (MN) in the first few cell cycles and that cells with MN tend to display cell cycle abnormalities. The powerful FuVis system thus demonstrates that even a single sporadic sister chromatid fusion can induce chromosome instability and destabilize the cell cycle through MN formation.
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Affiliation(s)
- Katsushi Kagaya
- The Hakubi Center for Advanced Research, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
- Seto Marine Biological Laboratory, Field Science, Education and Research Center, Kyoto University, Wakayama, Japan
| | - Naoto Noma-Takayasu
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
| | - Io Yamamoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
| | - Sanki Tashiro
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
| | - Makoto T Hayashi
- The Hakubi Center for Advanced Research, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Kyoto, Japan
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9
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Stehr JE, Balagula RM, Jansson M, Yukimune M, Fujiwara R, Ishikawa F, Chen WM, Buyanova IA. Effects of growth temperature and thermal annealing on optical quality of GaNAs nanowires emitting in the near-infrared spectral range. Nanotechnology 2020; 31:065702. [PMID: 31658456 DOI: 10.1088/1361-6528/ab51cd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report on optimization of growth conditions of GaAs/GaNAs/GaAs core/shell/shell nanowire (NW) structures emitting at ∼1 μm, aiming to increase their light emitting efficiency. A slight change in growth temperature is found to critically affect optical quality of the active GaNAs shell and is shown to result from suppressed formation of non-radiative recombination (NRR) centers under the optimum growth temperature. By employing the optically detected magnetic resonance spectroscopy, we identify gallium vacancies and gallium interstitials as being among the dominant NRR defects. The radiative efficiency of the NWs can be further improved by post-growth annealing at 680 °C, which removes the gallium interstitials.
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Affiliation(s)
- J E Stehr
- Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden
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10
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Leng H, Ohmura A, Anh LN, Ishikawa F, Naka T, Huang YK, de Visser A. Superconductivity under pressure in the Dirac semimetal PdTe 2. J Phys Condens Matter 2020; 32:025603. [PMID: 31574487 DOI: 10.1088/1361-648x/ab49b5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The Dirac semimetal PdTe2 was recently reported to be a type-I superconductor (T c = 1.64 K, [Formula: see text] mT) with unusual superconductivity of the surface sheath. We here report a high-pressure study, [Formula: see text] GPa, of the superconducting phase diagram extracted from ac-susceptibility and transport measurements on single crystalline samples. T c (p ) shows a pronounced non-monotonous variation with a maximum T c = 1.91 K around 0.91 GPa, followed by a gradual decrease to 1.27 K at 2.5 GPa. Surface superconductivity is robust under pressure as demonstrated by the large superconducting screening signal that persists for applied dc-fields [Formula: see text]. Surprisingly, for [Formula: see text] GPa the superconducting transition temperature at the surface [Formula: see text] is larger than T c of the bulk. Therefore surface superconductivity may possibly have a non-trivial topological nature. We compare the measured pressure variation of T c with recent results from band structure calculations and discuss the importance of a Van Hove singularity.
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Affiliation(s)
- H Leng
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - A Ohmura
- Pacific Rim Solar Fuel System Research Center, Niigata University, 8050, Ikarashi 2-no-cho, Nishi-ku, Niigata, 950-2181, Japan
- Faculty of Science, Niigata University, 8050, Ikarashi 2-no-cho, Nishi-ku, Niigata, 950-2181, Japan
| | - L N Anh
- International Training Institute for Materials Science, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Ha Noi, Vietnam
| | - F Ishikawa
- Faculty of Science, Niigata University, 8050, Ikarashi 2-no-cho, Nishi-ku, Niigata, 950-2181, Japan
| | - T Naka
- National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan
| | - Y K Huang
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - A de Visser
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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11
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Ishikawa S, Ishikawa F. Proteostasis failure and cellular senescence in long-term cultured postmitotic rat neurons. Aging Cell 2020; 19:e13071. [PMID: 31762159 PMCID: PMC6974705 DOI: 10.1111/acel.13071] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 10/05/2019] [Accepted: 10/29/2019] [Indexed: 12/31/2022] Open
Abstract
Cellular senescence, a stress-induced irreversible cell cycle arrest, has been defined for mitotic cells and is implicated in aging of replicative tissues. Age-related functional decline in the brain is often attributed to a failure of protein homeostasis (proteostasis), largely in postmitotic neurons, which accordingly is a process distinct by definition from senescence. It is nevertheless possible that proteostasis failure and cellular senescence have overlapping molecular mechanisms. Here, we identify postmitotic cellular senescence as an adaptive stress response to proteostasis failure. Primary rat hippocampal neurons in long-term cultures show molecular changes indicative of both senescence (senescence-associated β-galactosidase, p16, and loss of lamin B1) and proteostasis failure relevant to Alzheimer's disease. In addition, we demonstrate that the senescent neurons exhibit resistance to stress. Importantly, treatment of the cultures with an mTOR antagonist, protein synthesis inhibitor, or chemical compound that reduces the amount of protein aggregates relieved the proteotoxic stresses as well as the appearance of senescence markers. Our data propose mechanistic insights into the pathophysiological brain aging by establishing senescence as a primary cell-autonomous neuroprotective response.
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Affiliation(s)
- Shoma Ishikawa
- Department of Gene Mechanisms Graduate School of Biostudies Kyoto University Kyoto Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms Graduate School of Biostudies Kyoto University Kyoto Japan
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12
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Irie H, Yamamoto I, Tarumoto Y, Tashiro S, Runge KW, Ishikawa F. Telomere-binding proteins Taz1 and Rap1 regulate DSB repair and suppress gross chromosomal rearrangements in fission yeast. PLoS Genet 2019; 15:e1008335. [PMID: 31454352 PMCID: PMC6733473 DOI: 10.1371/journal.pgen.1008335] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 09/09/2019] [Accepted: 07/28/2019] [Indexed: 11/19/2022] Open
Abstract
Genomic rearrangements (gross chromosomal rearrangements, GCRs) threatens genome integrity and cause cell death or tumor formation. At the terminus of linear chromosomes, a telomere-binding protein complex, called shelterin, ensures chromosome stability by preventing chromosome end-to-end fusions and regulating telomere length homeostasis. As such, shelterin-mediated telomere functions play a pivotal role in suppressing GCR formation. However, it remains unclear whether the shelterin proteins play any direct role in inhibiting GCR at non-telomeric regions. Here, we have established a GCR assay for the first time in fission yeast and measured GCR rates in various mutants. We found that fission yeast cells lacking shelterin components Taz1 or Rap1 (mammalian TRF1/2 or RAP1 homologues, respectively) showed higher GCR rates compared to wild-type, accumulating large chromosome deletions. Genetic dissection of Rap1 revealed that Rap1 contributes to inhibiting GCRs via two independent pathways. The N-terminal BRCT-domain promotes faithful DSB repair, as determined by I-SceI-mediated DSB-induction experiments; moreover, association with Poz1 mediated by the central Poz1-binding domain regulates telomerase accessibility to DSBs, leading to suppression of de novo telomere additions. Our data highlight unappreciated functions of the shelterin components Taz1 and Rap1 in maintaining genome stability, specifically by preventing non-telomeric GCRs.
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Affiliation(s)
- Hiroyuki Irie
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Io Yamamoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yusuke Tarumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Sanki Tashiro
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kurt W. Runge
- Department of Molecular Genetics, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, United States of America
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, Japan
- * E-mail:
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13
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Maekawa T, Liu B, Nakai D, Yoshida K, Nakamura KI, Yasukawa M, Koike M, Takubo K, Chatton B, Ishikawa F, Masutomi K, Ishii S. ATF7 mediates TNF-α-induced telomere shortening. Nucleic Acids Res 2019; 46:4487-4504. [PMID: 29490055 PMCID: PMC5961373 DOI: 10.1093/nar/gky155] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 02/20/2018] [Indexed: 12/23/2022] Open
Abstract
Telomeres maintain the integrity of chromosome ends and telomere length is an important marker of aging. The epidemiological studies suggested that many types of stress including psychosocial stress decrease telomere length. However, it remains unknown how various stresses induce telomere shortening. Here, we report that the stress-responsive transcription factor ATF7 mediates TNF-α–induced telomere shortening. ATF7 and telomerase, an enzyme that elongates telomeres, are localized on telomeres via interactions with the Ku complex. In response to TNF-α, which is induced by various stresses including psychological stress, ATF7 was phosphorylated by p38, leading to the release of ATF7 and telomerase from telomeres. Thus, a decrease of ATF7 and telomerase on telomeres in response to stress causes telomere shortening, as observed in ATF7-deficient mice. These findings give credence to the idea that various types of stress might shorten telomere.
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Affiliation(s)
- Toshio Maekawa
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Binbin Liu
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
| | - Daisuke Nakai
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
| | - Keisuke Yoshida
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Ken-Ichi Nakamura
- Research Team for Geriatric Diseases, Tokyo Metropolitan Institute of Gerontology, Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015, Japan
| | - Mami Yasukawa
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo, Japan
| | - Manabu Koike
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Kaiyo Takubo
- Research Team for Geriatric Diseases, Tokyo Metropolitan Institute of Gerontology, Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015, Japan
| | - Bruno Chatton
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, BP10413, Illkirch, France
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kenkichi Masutomi
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo, Japan
| | - Shunsuke Ishii
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
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14
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Yukimune M, Fujiwara R, Mita T, Tsuda N, Natsui J, Shimizu Y, Jansson M, Balagula R, Chen WM, Buyanova IA, Ishikawa F. Molecular beam epitaxial growth of dilute nitride GaNAs and GaInNAs nanowires. Nanotechnology 2019; 30:244002. [PMID: 30794991 DOI: 10.1088/1361-6528/ab0974] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report the growth of dilute nitride GaNAs and GaInNAs core-multishell nanowires (NWs) using molecular beam epitaxy assisted by a plasma source. Using the self-catalyst vapor-liquid-solid growth mode, these NWs were grown on Si(111) and silicon on insulator substrates. The GaNAs and GaInNAs shells contain nitrogen up to 3%. Axial cross-sectional scanning transmission electron microscopy measurements and energy-dispersive x-ray spectrometry confirm the formation of the core-multishell NW structure. We obtained high-quality GaNAs NWs with nitrogen compositions up to 2%. On the other hand, GaNAs containing 3% nitrogen, and GaInNAs NWs, show distorted structures; moreover, the optical emissions seem to be related to defects. Further optimisations of the growth conditions will improve these properties, promising future applications in nanoscale optoelectronics.
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Affiliation(s)
- M Yukimune
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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15
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Takikawa M, Tarumoto Y, Ishikawa F. Fission yeast Stn1 is crucial for semi-conservative replication at telomeres and subtelomeres. Nucleic Acids Res 2017; 45:1255-1269. [PMID: 28180297 PMCID: PMC5388396 DOI: 10.1093/nar/gkw1176] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 11/08/2016] [Accepted: 11/23/2016] [Indexed: 12/29/2022] Open
Abstract
The CST complex is a phylogenetically conserved protein complex consisting of CTC1/Cdc13, Stn1 and Ten1 that protects telomeres on linear chromosomes. Deletion of the fission yeast homologs stn1 and ten1 results in complete telomere loss; however, the precise function of Stn1 is still largely unknown. Here, we have isolated a high-temperature sensitive stn1 allele (termed stn1-1). stn1-1 cells abruptly lost telomeric sequence almost completely at the restrictive temperature. The loss of chromosomal DNA happened without gradual telomere shortening, and extended to 30 kb from the ends of chromosomes. We found transient and modest single-stranded G-strand exposure, but did not find any evidence of checkpoint activation in stn1-1 at the restrictive temperature. When we probed neutral-neutral 2D gels for subtelomere regions, we found no Y-arc-shaped replication intermediates in cycling cells. We conclude that the loss of telomere and subtelomere DNAs in stn1-1 cells at the restrictive temperature is caused by very frequent replication fork collapses specifically in subtelomere regions. Furthermore, we identified two independent suppressor mutants of the high-temperature sensitivity of stn1-1: a multi-copy form of pmt3 and a deletion of rif1. Collectively, we propose that fission yeast Stn1 primarily safeguards the semi-conservative DNA replication at telomeres and subtelomeres.
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Affiliation(s)
- Masahiro Takikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Yusuke Tarumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
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16
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Zhou QG, Liu MY, Lee HW, Ishikawa F, Devkota S, Shen XR, Jin X, Wu HY, Liu Z, Liu X, Jin X, Zhou HH, Ro EJ, Zhang J, Zhang Y, Lin YH, Suh H, Zhu DY. Hippocampal TERT Regulates Spatial Memory Formation through Modulation of Neural Development. Stem Cell Reports 2017; 9:543-556. [PMID: 28757168 PMCID: PMC5550029 DOI: 10.1016/j.stemcr.2017.06.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/27/2017] [Accepted: 06/27/2017] [Indexed: 01/29/2023] Open
Abstract
The molecular mechanism of memory formation remains a mystery. Here, we show that TERT, the catalytic subunit of telomerase, gene knockout (Tert−/−) causes extremely poor ability in spatial memory formation. Knockdown of TERT in the dentate gyrus of adult hippocampus impairs spatial memory processes, while overexpression facilitates it. We find that TERT plays a critical role in neural development including dendritic development and neuritogenesis of hippocampal newborn neurons. A monosynaptic pseudotyped rabies virus retrograde tracing method shows that TERT is required for neural circuit integration of hippocampal newborn neurons. Interestingly, TERT regulated neural development and spatial memory formation in a reverse transcription activity-independent manner. Using X-ray irradiation, we find that hippocampal newborn neurons mediate the modulation of spatial memory processes by TERT. These observations reveal an important function of TERT through a non-canonical pathway and encourage the development of a TERT-based strategy to treat neurological disease-associated memory impairment. Tert gene knockout causes extremely poor ability in spatial memory formation Dendritic development and neuritogenesis are impaired in Tert−/− mice TERT is required for neural circuit integration of hippocampal newborn neurons TERT regulates spatial memory formation in an activity-independent manner
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Affiliation(s)
- Qi-Gang Zhou
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China; Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Meng-Ying Liu
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Han-Woong Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei Laboratory Animal Research Center, Yonsei University, Seoul 120-749, Korea
| | - Fuyuki Ishikawa
- Departments of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto 606-850, Japan
| | - Sushil Devkota
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei Laboratory Animal Research Center, Yonsei University, Seoul 120-749, Korea
| | - Xin-Ru Shen
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Xin Jin
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Hai-Yin Wu
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Zhigang Liu
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Xiao Liu
- Department of Chinese Medicine, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, P.R. China
| | - Xun Jin
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325015 Zhejiang, P.R. China
| | - Hai-Hui Zhou
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Eun Jeoung Ro
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Jing Zhang
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Yu Zhang
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Yu-Hui Lin
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China
| | - Hoonkyo Suh
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Dong-Ya Zhu
- Department of Clinical Pharmacology, Institution of Stem Cells and Neuroregeneration, Pharmacy College, Nanjing Medical University, Nanjing 211166, P.R. China.
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17
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Furubayashi T, Motohashi K, Wakao K, Matsuda T, Kii I, Hosoya T, Hayashi N, Sadaie M, Ishikawa F, Matsushita M, Fujiyoshi S. Three-Dimensional Localization of an Individual Fluorescent Molecule with Angstrom Precision. J Am Chem Soc 2017. [PMID: 28644014 DOI: 10.1021/jacs.7b03899] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Among imaging techniques, fluorescence microscopy is a unique method to noninvasively image individual molecules in whole cells. If the three-dimensional spatial precision is improved to the angstrom level, various molecular arrangements in the cell can be visualized on an individual basis. We have developed a cryogenic reflecting microscope with a numerical aperture of 0.99 and an imaging stability of 0.05 nm in standard deviation at a temperature of 1.8 K. The key optics to realize the cryogenic performances is the reflecting objective developed by our laboratory. With this cryogenic microscope, an individual fluorescent molecule (ATTO647N) at 1.8 K was localized with standard errors of 0.53 nm (x), 0.31 nm (y), and 0.90 nm (z) when 106 fluorescence photons from the molecule were accumulated in 5 min.
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Affiliation(s)
| | | | | | | | - Isao Kii
- Pathophysiological and Health Science Team, Imaging Platform and Innovation Group, Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies , Chuo, Kobe, 650-0047, Japan
| | - Takamitsu Hosoya
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , Chiyoda, Tokyo, 101-0062, Japan
| | | | - Mahito Sadaie
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University , Sakyo, Kyoto, 606-8501, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University , Sakyo, Kyoto, 606-8501, Japan
| | | | - Satoru Fujiyoshi
- Japan Science and Technology Agency, PRESTO , Kawaguchi, Saitama, 332-0012, Japan
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18
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Filippov S, Jansson M, Stehr JE, Palisaitis J, Persson POÅ, Ishikawa F, Chen WM, Buyanova IA. Strongly polarized quantum-dot-like light emitters embedded in GaAs/GaNAs core/shell nanowires. Nanoscale 2016; 8:15939-15947. [PMID: 27537077 DOI: 10.1039/c6nr05168e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent developments in fabrication techniques and extensive investigations of the physical properties of III-V semiconductor nanowires (NWs), such as GaAs NWs, have demonstrated their potential for a multitude of advanced electronic and photonics applications. Alloying of GaAs with nitrogen can further enhance the performance and extend the device functionality via intentional defects and heterostructure engineering in GaNAs and GaAs/GaNAs coaxial NWs. In this work, it is shown that incorporation of nitrogen in GaAs NWs leads to formation of three-dimensional confining potentials caused by short-range fluctuations in the nitrogen composition, which are superimposed on long-range alloy disorder. The resulting localized states exhibit a quantum-dot like electronic structure, forming optically active states in the GaNAs shell. By directly correlating the structural and optical properties of individual NWs, it is also shown that formation of the localized states is efficient in pure zinc-blende wires and is further facilitated by structural polymorphism. The light emission from these localized states is found to be spectrally narrow (∼50-130 μeV) and is highly polarized (up to 100%) with the preferable polarization direction orthogonal to the NW axis, suggesting a preferential orientation of the localization potential. These properties of self-assembled nano-emitters embedded in the GaNAs-based nanowire structures may be attractive for potential optoelectronic applications.
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Affiliation(s)
- S Filippov
- Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden.
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19
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Oki T, Kano M, Ishikawa F, Goto K, Watanabe O, Suda I. Double-blind, placebo-controlled pilot trial of anthocyanin-rich purple sweet potato beverage on serum hepatic biomarker levels in healthy Caucasians with borderline hepatitis. Eur J Clin Nutr 2016; 71:290-292. [PMID: 27530473 DOI: 10.1038/ejcn.2016.153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 06/02/2016] [Accepted: 06/18/2016] [Indexed: 02/04/2023]
Abstract
The objective is to evaluate the efficacy of anthocyanin-rich purple-fleshed sweet potato (PSP) beverage on the serum levels of gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in healthy Caucasians with borderline hepatitis. Forty healthy Caucasians (41-69 years) consumed three bottles of the PSP beverage (177 mg anthocyanins per 125-ml bottle) or placebo (1.3 mg) per day for 8 weeks. Thirty-nine subjects completed the study and two subjects were excluded from statistical analysis. GGT levels in the PSP group on days 15 and 43 were lower (P=0.077 and 0.038, respectively), AST levels in the PSP group on days 29 and 43 were lower (P=0.010 and 0.045, respectively) and ALT level in the PSP group on day 43 was lower (P=0.037) than in the placebo group. The PSP beverage did not induce clinically relevant changes in other blood and clinical chemistry parameters.
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Affiliation(s)
- T Oki
- Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Koshi, Kumamoto, Japan
| | - M Kano
- Yakult Central Institute, Kunitachi, Tokyo, Japan
| | - F Ishikawa
- Yakult Central Institute, Kunitachi, Tokyo, Japan
| | - K Goto
- Agri-Food Business Innovation Center, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - O Watanabe
- Faculty of Research and Development, Yakult Honsha Co., Ltd., Minato, Tokyo, Japan
| | - I Suda
- Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Koshi, Kumamoto, Japan
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20
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Hirai Y, Tamura M, Otani J, Ishikawa F. NEK6-mediated phosphorylation of human TPP1 regulates telomere length through telomerase recruitment. Genes Cells 2016; 21:874-89. [DOI: 10.1111/gtc.12391] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/31/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Yugo Hirai
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
| | - Miki Tamura
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
| | - Junji Otani
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
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21
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Kodaira S, Kurano M, Hosogane T, Ishikawa F, Kageyama T, Sato M, Kayano M, Yasuda N. Note: Application of CR-39 plastic nuclear track detectors for quality assurance of mixed oxide fuel pellets. Rev Sci Instrum 2015; 86:056103. [PMID: 26026564 DOI: 10.1063/1.4919904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A CR-39 plastic nuclear track detector was used for quality assurance of mixed oxide fuel pellets for next-generation nuclear power plants. Plutonium (Pu) spot sizes and concentrations in the pellets are significant parameters for safe use in the plants. We developed an automatic Pu detection system based on dense α-radiation tracks in the CR-39 detectors. This system would greatly improve image processing time and measurement accuracy, and will be a powerful tool for rapid pellet quality assurance screening.
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Affiliation(s)
- S Kodaira
- Radiation Measurement Research Section, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - M Kurano
- Radiation Measurement Research Section, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - T Hosogane
- Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, Ibaraki 319-1194, Japan
| | - F Ishikawa
- Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, Ibaraki 319-1194, Japan
| | - T Kageyama
- Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, Ibaraki 319-1194, Japan
| | - M Sato
- Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, Ibaraki 319-1194, Japan
| | - M Kayano
- Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, Ibaraki 319-1194, Japan
| | - N Yasuda
- Research Institute of Nuclear Engineering, University of Fukui, Fukui 914-0055, Japan
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22
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Gomi A, Iino T, Nonaka C, Miyazaki K, Ishikawa F. Health benefits of fermented milk containing Bifidobacterium bifidum YIT 10347 on gastric symptoms in adults. J Dairy Sci 2015; 98:2277-83. [PMID: 25648808 DOI: 10.3168/jds.2014-9158] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/12/2014] [Indexed: 12/19/2022]
Abstract
We conducted a preliminary open trial (trial 1) and a double-blind, placebo-controlled, crossover trial (trial 2) to examine how fermented milk containing the probiotic Bifidobacterium bifidum YIT 10347 affects gastric and lower abdominal symptoms in adults taking no medication. In trial 1, subjects with or without gastric and lower abdominal symptoms ingested fermented milk containing B. bifidum YIT 10347 daily for 2 wk. In trial 2, subjects with gastric symptoms ingested fermented milk containing B. bifidum YIT 10347 (active preparation) or placebo daily for 2 wk, followed by crossover for 3 wk after a washout period. Before (baseline) and 1 and 2 wk after ingestion, subjects completed a questionnaire. In trial 1 (305 subjects), the prevalence of gastric and lower abdominal symptoms was 46 and 58%, respectively, at baseline. Ingestion of B. bifidum YIT 10347 significantly decreased the prevalence of gastric and lower abdominal symptoms from 45 to 33% at 1 wk and to 28% at 2 wk, and from 57 to 40% at 2 wk, respectively. In subjects with gastric symptoms at baseline, the average gastric symptom score per subject significantly decreased by 0.9 at 1 wk and 1.2 at 2 wk. In trial 2 (27 subjects), ingestion of the active preparation significantly decreased the average gastric symptoms score per subject by 1.0 at 1 wk and 1.1 at 2 wk, but ingestion of placebo milk had no effect. No side effects were reported by any subjects in either trial. We conclude that fermented milk containing B. bifidum YIT 10347 has the potential to provide health benefits by alleviating gastric symptoms in subjects taking no medication.
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Affiliation(s)
- A Gomi
- Yakult Central Institute, Kunitachi, Tokyo 186-8650, Japan.
| | - T Iino
- Yakult Central Institute, Kunitachi, Tokyo 186-8650, Japan
| | - C Nonaka
- Faculty of Research and Development, Yakult Honsha, Shimbashi, Tokyo 105-8660, Japan
| | - K Miyazaki
- Yakult Central Institute, Kunitachi, Tokyo 186-8650, Japan
| | - F Ishikawa
- Yakult Central Institute, Kunitachi, Tokyo 186-8650, Japan
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23
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Yamazaki H, Ishikawa F. [Telomere maintenance by DNA damage sensor kinases, ATM and ATR]. Seikagaku 2014; 86:812-816. [PMID: 25675824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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Abstract
AbstractA nine-year-old girl with short stature was referred to the department of pediatrics at Kyushu University. The clinical diagnosis was Turner syndrome; karyotypic analysis performed on peripheral blood, using GTG techniques, demonstrated a 45,X/47,XYY (17:83) mosaicism. Her twin brother, a phenotypically normal male, had the same karyotype; 45,X/47,XYY (3:97) on peripheral blood. Their skin fibroblast karyotypes showed the same mosaicism, ie. 45,X/47,XYY (41:59 and 31:69 respectively). On eleven biochemical genetic markers the twin pair were concordant, thus the likelihood of monozygosity was 0.99527034. In addition, the analysis of variable number of tandem repeat (VNTR) markers revealed the likelihood of monozygosity to be 0.99944386. The most plausible explanation of the X/XYY mosaicism was nondisjunction of the Y in the first cleavage division of the 46,XY zygote. A disproportionate rate of cell populations with 45,X and 47.XYY in the twinning process of the X/XYY embryo, especially in the germ lines, would result in discordant sex in twin pairs.
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Affiliation(s)
- K Kurosawa
- Division of Medical Genetics, Kanagawa Children's Medical Center, Japan
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25
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Wakai M, Abe S, Kazuki Y, Oshimura M, Ishikawa F. A human artificial chromosome recapitulates the metabolism of native telomeres in mammalian cells. PLoS One 2014; 9:e88530. [PMID: 24558398 PMCID: PMC3928237 DOI: 10.1371/journal.pone.0088530] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/07/2014] [Indexed: 01/03/2023] Open
Abstract
Telomeric and subtelomeric regions of human chromosomes largely consist of highly repetitive and redundant DNA sequences, resulting in a paucity of unique DNA sequences specific to individual telomeres. Accordingly, it is difficult to analyze telomere metabolism on a single-telomere basis. To circumvent this problem, we have exploited a human artificial chromosome (HAC#21) derived from human chromosome 21 (hChr21). HAC#21 was generated through truncation of the long arm of native hChr21 by the targeted telomere seeding technique. The newly established telomere of HAC#21 lacks canonical subtelomere structures but possesses unique sequences derived from the target vector backbone and the internal region of hChr21 used for telomere targeting, which enabled us to molecularly characterize the single HAC telomere. We established HeLa and NIH-3T3 sub-lines containing a single copy of HAC#21, where it was robustly maintained. The seeded telomere is associated with telomeric proteins over a length similar to that reported in native telomeres, and is faithfully replicated in mid-S phase in HeLa cells. We found that the seeded telomere on HAC#21 is transcribed from the newly juxtaposed site. The transcript, HAC-telRNA, shares several features with TERRA (telomeric repeat-containing RNA): it is a short-lived RNA polymerase II transcript, rarely contains a poly(A) tail, and associates with chromatin. Interestingly, HAC-telRNA undergoes splicing. These results suggest that transcription into TERRA is locally influenced by the subtelomeric context. Taken together, we have established human and mouse cell lines that will be useful for analyzing the behavior of a uniquely identifiable, functional telomere.
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Affiliation(s)
- Michihito Wakai
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Satoshi Abe
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, Japan
| | - Yasuhiro Kazuki
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, Japan
- Chromosome Engineering Research Center, Tottori University, Tottori, Japan
| | - Mitsuo Oshimura
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, Japan
- Chromosome Engineering Research Center, Tottori University, Tottori, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
- * E-mail:
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26
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Nishiyama A, Yamaguchi L, Sharif J, Johmura Y, Kawamura T, Nakanishi K, Shimamura S, Arita K, Kodama T, Ishikawa F, Koseki H, Nakanishi M. Uhrf1-dependent H3K23 ubiquitylation couples maintenance DNA methylation and replication. Nature 2013; 502:249-53. [DOI: 10.1038/nature12488] [Citation(s) in RCA: 252] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 07/18/2013] [Indexed: 12/18/2022]
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Naka T, Sato K, Taguchi M, Shirakawa N, Nakane T, Ishikawa F, Yamada Y, Takaesu Y, Nakama T, Matsushita A. Characteristics of a granular electronic system in Heusler-type Fe2+xV1-xAl. J Phys Condens Matter 2013; 25:275603. [PMID: 23774462 DOI: 10.1088/0953-8984/25/27/275603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report comprehensive measurements of the magnetic, transport, and thermal properties of the Heusler-type compound Fe2+xV1-xAl, with x values near the ferromagnetic quantum critical point, xc ∼ 0.05. At T ∼ 60 K, a prominent Schottky-like anomaly appeared in the specific heat; this anomaly was correlated with a smaller pseudo-gap formation in magnetic susceptibility, magnetoresistance, and thermoelectric power. Furthermore, a magnetic anomaly observed in the magnetic susceptibility and resistivity at T ∼ 4 K was suppressed significantly by applying a magnetic field. A magnetically inhomogeneous phase arose below T ∼ 60 K, which appeared to consist of ferromagnetic and paramagnetic clusters.
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Affiliation(s)
- T Naka
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
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28
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Tarumoto Y, Kanoh J, Ishikawa F. Receptor for activated C-kinase (RACK1) homolog Cpc2 facilitates the general amino acid control response through Gcn2 kinase in fission yeast. J Biol Chem 2013; 288:19260-8. [PMID: 23671279 DOI: 10.1074/jbc.m112.445270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
General amino acid control (GAAC) is crucial for sensing and adaptation to nutrient availability. Amino acid starvation activates protein kinase Gcn2, which plays a central role in the GAAC response by phosphorylating the α-subunit of eukaryotic initiation factor 2 (eIF2α), leading to the translational switch to stimulate selective expression of stress-responsive genes. We report here that in fission yeast Schizosaccharomyces pombe, Cpc2, a homolog of mammalian receptor for activated C-kinase (RACK1), is important for the GAAC response. Deletion of S. pombe cpc2 impairs the amino acid starvation-induced phosphorylation of eIF2α and the expression of amino acid biosynthesis genes, thereby rendering cells severely sensitive to amino acid limitation. Unlike the Saccharomyces cerevisiae Cpc2 ortholog, which normally suppresses the GAAC response, our findings suggest that S. pombe Cpc2 promotes the GAAC response. We also found that S. pombe Cpc2 is required for starvation-induced Gcn2 autophosphorylation, which is essential for Gcn2 function. These results indicate that S. pombe Cpc2 facilitates the GAAC response through the regulation of Gcn2 activation and provide a novel insight for the regulatory function of RACK1 on Gcn2-mediated GAAC response.
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Affiliation(s)
- Yusuke Tarumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Abstract
Genetic instability is the driving force of the malignant progression of cancer cells. Recently, replication stress has attracted much attention as a source of genetic instability that gives rise to an accumulation of mutations during the lifespan of individuals. However, the molecular details of the process are not fully understood. Here, recent progress in understanding how genetic alterations accumulate at telomeres will be reviewed. In particular, two aspects of telomere replication will be discussed in this context, covering conventional semi-conservative replication, and DNA synthesis by telomerase plus the C-strand fill-in reactions. Although these processes are seemingly telomere-specific, I will emphasize the possibility that the molecular understanding of the telomere events may shed light on genetic instability at other genetic loci in general.
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Affiliation(s)
- Fuyuki Ishikawa
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
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Tashiro S, Asano T, Kanoh J, Ishikawa F. Transcription-induced chromatin association of RNA surveillance factors mediates facultative heterochromatin formation in fission yeast. Genes Cells 2013; 18:327-39. [PMID: 23388053 DOI: 10.1111/gtc.12038] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 12/22/2012] [Indexed: 02/01/2023]
Abstract
Facultative heterochromatin is reversibly established and disrupted during differentiation, but its regulation remains mechanistically unclear. Here, we show that two meiotic gene loci in fission yeast, mei4 and ssm4, comprise facultative heterochromatin that is regulated in a developmental stage-dependent manner. This heterochromatin coordinates expression levels by associating with a chromodomain protein Chp1 and an antisilencing factor Epe1. It has been recently shown that an RNA surveillance machinery for eliminating meiotic gene transcripts, which involves a cis-element called the determinant of selective removal (DSR) and transacting factors, Mmi1 and Red1, also participates in heterochromatin formation at the meiotic genes, but the molecular mechanism underlying the process is largely unknown. By dissecting the mei4 gene, we identified a region that promotes DSR-dependent methylation of histone H3 lysine 9 (H3K9). Integration of this mei4 region together with DSR into an unrelated gene results in ectopic H3K9 methylation. Moreover, our results suggest that transcription of these elements induces chromatin association of Mmi1, which, in turn, recruits Red1 interacting with Clr4/Suv39h H3K9 methyltransferase. Mmi1 remains associated in cells lacking Red1, suggesting that the recruitment of Red1 follows the chromatin association of Mmi1. Overall, we provide detailed insights into the facultative heterochromatin regulation in fission yeast.
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Affiliation(s)
- Sanki Tashiro
- Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
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Tanimura N, Saito M, Ebisuya M, Nishida E, Ishikawa F. Stemness-related factor Sall4 interacts with transcription factors Oct-3/4 and Sox2 and occupies Oct-Sox elements in mouse embryonic stem cells. J Biol Chem 2012; 288:5027-38. [PMID: 23269686 DOI: 10.1074/jbc.m112.411173] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A small number of transcription factors, including Oct-3/4 and Sox2, constitute the transcriptional network that maintains pluripotency in embryonic stem (ES) cells. Previous reports suggested that some of these factors form a complex that binds the Oct-Sox element, a composite sequence consisting of closely juxtaposed Oct-3/4 binding and Sox2 binding sites. However, little is known regarding the components of the complex. In this study we show that Sall4, a member of the Spalt-like family of proteins, directly interacts with Sox2 and Oct-3/4. Sall4 in combination with Sox2 or Oct-3/4 simultaneously occupies the Oct-Sox elements in mouse ES cells. Overexpression of Sall4 in ES cells increased reporter activities in a luciferase assay when the Pou5f1- or Nanog-derived Oct-Sox element was included in the reporter. Microarray analyses revealed that Sall4 and Sox2 bound to the same genes in ES cells significantly more frequently than expected from random coincidence. These factors appeared to bind the promoter regions of a subset of the Sall4 and Sox2 double-positive genes in precisely similar distribution patterns along the promoter regions, suggesting that Sall4 and Sox2 associate with such Sall4/Sox2-overlapping genes as a complex. Importantly, gene ontology analyses indicated that the Sall4/Sox2-overlapping gene set is enriched for genes involved in maintaining pluripotency. Sall4/Sox2/Oct-3/4 triple-positive genes identified by referring to a previous study identifying Oct-3/4-bound genes in ES cells were further enriched for pluripotency genes than Sall4/Sox2 double-positive genes. These results demonstrate that Sall4 contributes to the transcriptional network operating in pluripotent cells together with Oct-3/4 and Sox2.
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Affiliation(s)
- Nobuyuki Tanimura
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Gomi A, Harima-Mizusawa N, Shibahara-Sone H, Kano M, Miyazaki K, Ishikawa F. Effect of Bifidobacterium bifidum BF-1 on gastric protection and mucin production in an acute gastric injury rat model. J Dairy Sci 2012. [PMID: 23200466 DOI: 10.3168/jds.2012-5950] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Homeostasis in the stomach environment is maintained by the balance of protective factors such as gastric mucus and aggressive factors such as gastric acid, stress, alcohol, and drugs. An overload of aggressive factors that upsets this balance can induce gastric injury. Fermented milk that contains Bifidobacterium bifidum BF-1 (BF-1), a probiotic strain, and Streptococcus thermophilus YIT 2021 (ST) is known to improve Helicobacter pylori-associated gastritis in humans. Here, we investigated the gastroprotective potential of BF-1 in a rat model of acid-ethanol-induced acute gastric injury to fully elucidate its potential compared with ST. Living BF-1, ST, or vehicle was orally administrated to rats, and acid-ethanol gastric injury was induced 2h later. The gastric injury rate was determined and shown to be significantly lower in the BF-1 group than in the vehicle group, which showed a similar level to the ST group. The production of gastric mucin and the expression of several target genes associated with protection and inflammation were examined before and after induction of gastric injury. Interestingly, mucin 5ac (muc5ac) gene expression in gastric corpus samples and gastric mucin production in stomach samples from the BF-1 group, but not the ST group, were significantly higher than those in the respective samples from the vehicle group. These findings indicate that BF-1 has the potential to provide gastroprotection, alleviating acute gastric injury by enhancing the production of gastric mucin in a rat model.
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Affiliation(s)
- A Gomi
- Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, 186-8650, Japan.
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33
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Ishikawa F. [Telomere dysfunction in cancer progression]. Rinsho Ketsueki 2012; 53:1849-1856. [PMID: 23037760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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34
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Ishikawa F. Targeting Chemotherapy-Resistant AML Stem Cells. Ann Oncol 2012. [DOI: 10.1016/s0923-7534(20)32096-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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35
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Fujita I, Nishihara Y, Tanaka M, Tsujii H, Chikashige Y, Watanabe Y, Saito M, Ishikawa F, Hiraoka Y, Kanoh J. Telomere-nuclear envelope dissociation promoted by Rap1 phosphorylation ensures faithful chromosome segregation. Curr Biol 2012; 22:1932-7. [PMID: 22959349 DOI: 10.1016/j.cub.2012.08.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/28/2012] [Accepted: 08/09/2012] [Indexed: 11/19/2022]
Abstract
Efficient chromosomal movements are important for the fidelity of chromosome segregation during mitosis; however, movements are constrained during interphase by tethering of multiple domains to the nuclear envelope (NE). Higher eukaryotes undergo open mitosis accompanied by NE breakdown, enabling chromosomes to be released from the NE, whereas lower eukaryotes undergo closed mitosis, in which NE breakdown does not occur. Although the chromosomal movements in closed mitosis are thought to be restricted compared to open mitosis, the cells overcome this problem by an unknown mechanism that enables accurate chromosome segregation. Here, we report the spatiotemporal regulation of telomeres in Schizosaccharomyces pombe closed mitosis. We found that the telomeres, tethered to the NE during interphase, are transiently dissociated from the NE during mitosis. This dissociation from the NE is essential for accurate chromosome segregation because forced telomere tethering to the NE causes frequent chromosome loss. The phosphorylation of the telomere protein Rap1 during mitosis, primarily by Cdc2, impedes the interaction between Rap1 and Bqt4, a nuclear membrane protein, thereby inducing telomere dissociation from the NE. We propose that the telomere dissociation from the NE promoted by Rap1 phosphorylation is critical for the fidelity of chromosome segregation in closed mitosis.
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Affiliation(s)
- Ikumi Fujita
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
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36
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Abstract
Comment on: Leman AR, et al. Cell Cycle 2012; 11:2337-47.
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37
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Yagi T, Kosakai A, Ito D, Okada Y, Akamatsu W, Nihei Y, Nabetani A, Ishikawa F, Arai Y, Hirose N, Okano H, Suzuki N. Establishment of induced pluripotent stem cells from centenarians for neurodegenerative disease research. PLoS One 2012; 7:e41572. [PMID: 22848530 PMCID: PMC3405135 DOI: 10.1371/journal.pone.0041572] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 06/26/2012] [Indexed: 12/19/2022] Open
Abstract
Induced pluripotent stem cell (iPSC) technology can be used to model human disorders, create cell-based models of human diseases, including neurodegenerative diseases, and in establishing therapeutic strategies. To detect subtle cellular abnormalities associated with common late-onset disease in iPSCs, valid control iPSCs derived from healthy donors free of serious late-onset diseases are necessary. Here, we report the generation of iPSCs from fibroblasts obtained immediately postmortem from centenarian donors (106- and 109-years-old) who were extremely healthy until an advanced age. The iPSCs were generated using a conventional method involving OCT4, SOX2, KLF4, and c-MYC, and then differentiated into neuronal cells using a neurosphere method. The expression of molecules that play critical roles in late-onset neurodegenerative diseases by neurons differentiated from the centenarian-iPSCs was compared to that of neurons differentiated from iPSCs derived from familial Alzheimer's disease and familial Parkinson's disease (PARK4: triplication of the α synuclein gene) patients. The results indicated that our series of iPSCs would be useful in neurodegeneration research. The iPSCs we describe, which were derived from donors with exceptional longevity who were presumed to have no serious disease risk factors, would be useful in longevity research and as valid super-controls for use in studies of various late-onset diseases.
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Affiliation(s)
- Takuya Yagi
- Department of Neurology, School of Medicine, Keio University, Tokyo, Japan
| | - Arifumi Kosakai
- Department of Neurology, School of Medicine, Keio University, Tokyo, Japan
| | - Daisuke Ito
- Department of Neurology, School of Medicine, Keio University, Tokyo, Japan
- * E-mail:
| | - Yohei Okada
- Department of Physiology, School of Medicine, Keio University, Tokyo, Japan
- Kanrinmaru Project, School of Medicine, Keio University, Tokyo, Japan
| | - Wado Akamatsu
- Department of Physiology, School of Medicine, Keio University, Tokyo, Japan
| | - Yoshihiro Nihei
- Department of Neurology, School of Medicine, Keio University, Tokyo, Japan
| | - Akira Nabetani
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Fuyuki Ishikawa
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Yasumichi Arai
- Division of Geriatric Medicine, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
| | - Nobuyoshi Hirose
- Division of Geriatric Medicine, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
| | - Hideyuki Okano
- Department of Physiology, School of Medicine, Keio University, Tokyo, Japan
| | - Norihiro Suzuki
- Department of Neurology, School of Medicine, Keio University, Tokyo, Japan
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Abstract
In most cancer cells, telomerase is activated to elongate telomere DNA, thereby ensuring numerous rounds of cell divisions. It is thus important to understand how telomerase and the replication fork react with telomeres in human cells. However, the highly polymorphic and repetitive nature of the nucleotide sequences in human subtelomeric regions hampers the precise analysis of sequential events taking place at telomeres in S phase. Here, we have established HeLa cells harboring a single-seeded telomere abutted by a unique subtelomere DNA sequence, which has enabled us to specifically focus on the seeded telomere. We have also developed a modified chromatin immunoprecipitation (ChIP) method that uses restriction digestion instead of sonication to fragment chromatin DNA (RES-ChIP), and a method for immunoprecipitating 5-bromo-2'-deoxyuridine (BrdU)-labeled single-stranded DNA by incubating DNA with anti-BrdU antibody in the nondenaturing condition. We have shown that DNA replication of the seeded telomere takes place during a relatively narrow time window in S phase, and telomerase synthesizes telomere DNA after the replication. Moreover, we have demonstrated that the telomerase catalytic subunit TERT associates with telomeres before telomere DNA replication. These results provide a temporal and spatial framework for understanding DNA replication and telomerase reaction at human telomeres.
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Affiliation(s)
- Yugo Hirai
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-Cho, Sakyo-Ku, Kyoto 606-8501, Japan
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Chujo M, Tarumoto Y, Miyatake K, Nishida E, Ishikawa F. HIRA, a conserved histone chaperone, plays an essential role in low-dose stress response via transcriptional stimulation in fission yeast. J Biol Chem 2012; 287:23440-50. [PMID: 22589550 DOI: 10.1074/jbc.m112.349944] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cells that have been pre-exposed to mild stress (priming stress) acquire transient resistance to subsequent severe stress even under different combinations of stresses. This phenomenon is called cross-tolerance. Although it has been reported that cross-tolerance occurs in many organisms, the molecular basis is not clear yet. Here, we identified slm9(+) as a responsible gene for the cross-tolerance in the fission yeast Schizosaccharomyces pombe. Slm9 is a homolog of mammalian HIRA histone chaperone. HIRA forms a conserved complex and gene disruption of other HIRA complex components, Hip1, Hip3, and Hip4, also yielded a cross-tolerance-defective phenotype, indicating that the fission yeast HIRA is involved in the cross-tolerance as a complex. We also revealed that Slm9 was recruited to the stress-responsive gene loci upon stress treatment in an Atf1-dependent manner. The expression of stress-responsive genes under stress conditions was compromised in HIRA disruptants. Consistent with this, Pol II recruitment and nucleosome eviction at these gene loci were impaired in slm9Δ cells. Furthermore, we found that the priming stress enhanced the expression of stress-responsive genes in wild-type cells that were exposed to the severe stress. These observations suggest that HIRA functions in stress response through transcriptional regulation.
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Affiliation(s)
- Moeko Chujo
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Yamazaki H, Tarumoto Y, Ishikawa F. Tel1(ATM) and Rad3(ATR) phosphorylate the telomere protein Ccq1 to recruit telomerase and elongate telomeres in fission yeast. Genes Dev 2012; 26:241-6. [PMID: 22302936 DOI: 10.1101/gad.177873.111] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In fission yeast, the DNA damage sensor kinases Tel1(ATM) and Rad3(ATR) exist at telomeres and are required for telomere maintenance, but the biological role they play at telomeres is not known. Here we show that the telomere protein Ccq1 is phosphorylated at Thr 93 (threonine residue at amino acid 93) by Tel1(ATM) and Rad3(ATR) both in vitro and in vivo. A ccq1 mutant in which alanine was substituted for Thr 93 failed to recruit telomerase to telomeres and showed gradual shortening of telomeres. These results indicate that the direct phosphorylation of Ccq1 Thr 93 by Tel1 and Rad3 is involved in the recruitment of telomerase to elongate telomeres.
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Affiliation(s)
- Harutake Yamazaki
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
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41
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Nakaoka H, Nishiyama A, Saito M, Ishikawa F. Xenopus laevis Ctc1-Stn1-Ten1 (xCST) protein complex is involved in priming DNA synthesis on single-stranded DNA template in Xenopus egg extract. J Biol Chem 2011; 287:619-627. [PMID: 22086929 PMCID: PMC3249116 DOI: 10.1074/jbc.m111.263723] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The Ctc1-Stn1-Ten1 (CST) complex is an RPA (replication protein A)-like protein complex that binds to single-stranded (ss) DNA. It localizes at telomeres and is involved in telomere end protection in mammals and plants. It is also known to stimulate DNA polymerase α-primase in vitro. However, it is not known how CST accomplishes these functions in vivo. Here, we report the identification and characterization of Xenopus laevis CST complex (xCST). xCST showed ssDNA binding activity with moderate preference for G (guanine)-rich sequences. xStn1-immunodepleted Xenopus egg extracts supported chromosomal DNA replication in in vitro reconstituted sperm nuclei, suggesting that xCST is not a general replication factor. However, the immunodepletion or neutralization of xStn1 compromised DNA synthesis on ssDNA template. Because primed ssDNA template was replicated in xStn1-immunodepleted extracts as efficiently as in control ones, we conclude that xCST is involved in the priming step on ssDNA template. These results are consistent with the current model that CST is involved in telomeric C-strand synthesis through the regulation of DNA polymerase α-primase.
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Affiliation(s)
- Hidenori Nakaoka
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Atsuya Nishiyama
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Motoki Saito
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Fuyuki Ishikawa
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
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Asano T, Komatsu M, Yamaguchi-Iwai Y, Ishikawa F, Mizushima N, Iwai K. Distinct mechanisms of ferritin delivery to lysosomes in iron-depleted and iron-replete cells. Mol Cell Biol 2011; 31:2040-52. [PMID: 21444722 PMCID: PMC3133360 DOI: 10.1128/mcb.01437-10] [Citation(s) in RCA: 184] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Accepted: 03/14/2011] [Indexed: 01/07/2023] Open
Abstract
Ferritin is a cytosolic protein that stores excess iron, thereby protecting cells from iron toxicity. Ferritin-stored iron is believed to be utilized when cells become iron deficient; however, the mechanisms underlying the extraction of iron from ferritin have yet to be fully elucidated. Here, we demonstrate that ferritin is degraded in the lysosome under iron-depleted conditions and that the acidic environment of the lysosome is crucial for iron extraction from ferritin and utilization by cells. Ferritin was targeted for degradation in the lysosome even under iron-replete conditions in primary cells; however, the mechanisms underlying lysosomal targeting of ferritin were distinct under depleted and replete conditions. In iron-depleted cells, ferritin was targeted to the lysosome via a mechanism that involved autophagy. In contrast, lysosomal targeting of ferritin in iron-replete cells did not involve autophagy. The autophagy-independent pathway of ferritin delivery to lysosomes was deficient in several cancer-derived cells, and cancer-derived cell lines are more resistant to iron toxicity than primary cells. Collectively, these results suggest that ferritin trafficking may be differentially regulated by cell type and that loss of ferritin delivery to the lysosome under iron-replete conditions may be related to oncogenic cellular transformation.
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Affiliation(s)
- Takeshi Asano
- Department of Biophysics and Biochemistry, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
- CREST, Japan Science Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
| | - Masaaki Komatsu
- Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
| | - Yuko Yamaguchi-Iwai
- Department of Applied Molecular Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8503, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Noboru Mizushima
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Kazuhiro Iwai
- Department of Biophysics and Biochemistry, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
- CREST, Japan Science Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
- Metabolism Group, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
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Naito E, Yoshida Y, Makino K, Kounoshi Y, Kunihiro S, Takahashi R, Matsuzaki T, Miyazaki K, Ishikawa F. Beneficial effect of oral administration of Lactobacillus casei strain Shirota on insulin resistance in diet-induced obesity mice. J Appl Microbiol 2011; 110:650-7. [PMID: 21281408 DOI: 10.1111/j.1365-2672.2010.04922.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AIMS This study aimed at determining whether oral administration of a probiotic strain, Lactobacillus casei strain Shirota (LcS), can improve insulin resistance, which is the underlying cause of obesity-associated metabolic abnormalities, in diet-induced obesity (DIO) mice. METHODS AND RESULTS DIO mice were fed a high-fat diet without or with 0·05% LcS for 4 weeks and then subjected to an insulin tolerance test (ITT) or oral glucose tolerance test (OGTT). Oral administration of LcS not only accelerated the reduction in plasma glucose levels during the ITT, but also reduced the elevation of plasma glucose levels during the OGTT. In addition, plasma levels of lipopolysaccharide-binding protein (LBP), which is a marker of endotoxaemia, were augmented in the murine models of obese DIO, ob/ob, db/db and KK-A(y) and compared to those of lean mice. LcS treatment suppressed the elevation of plasma LBP levels in DIO mice, but did not affect intra-abdominal fat weight. CONCLUSIONS LcS improves insulin resistance and glucose intolerance in DIO mice. The reduction in endotoxaemia, but not intra-abdominal fat, may contribute to the beneficial effects of LcS. SIGNIFICANCE AND IMPACT OF THE STUDY This study suggests that LcS has the potential to prevent obesity-associated metabolic abnormalities by improving insulin resistance.
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Affiliation(s)
- E Naito
- Yakult Central Institute for Microbiological Research, Kunitachi-shi, Tokyo, Japan
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Abstract
Unlimitedly proliferating cells need to acquire the telomere DNA maintenance mechanism, to counteract possible shortening through multiple rounds of replication and segregation of linear chromosomes. Most human cancer cells express telomerase whereas the other cells utilize the alternative lengthening of telomeres (ALT) pathway to elongate telomere DNA. It is suggested that ALT depends on the recombination between telomere repetitive DNAs. However, the molecular details remain unknown. Recent studies have provided evidence of special structures of telomere DNA and genes essential for the phenotypes of ALT cells. The molecular models of the ALT pathway should be validated to elucidate recombination-mediated telomere maintenance and promote the applications to anti-cancer therapy.
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Affiliation(s)
- Akira Nabetani
- Laboratory of Cell Cycle Regulation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University,Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
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Ishikawa B, Ishikawa F, Nakamura M, Otsuki H, Masubuchi N, Fukami T, Kaga K. P37-20 Absence of P300 and presence of N1 in two patients after herpes encephalitis. Clin Neurophysiol 2010. [DOI: 10.1016/s1388-2457(10)61337-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ishikawa B, Ishikawa F, Nakamura M, Otsuki H, Masubuchi N, Fukami T, Kaga K. P4-14 P300 ERP of normal young adults. Clin Neurophysiol 2010. [DOI: 10.1016/s1388-2457(10)60509-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Shirasawa Y, Shibahara-Sone H, Iino T, Ishikawa F. Bifidobacterium bifidum BF-1 suppresses Helicobacter pylori-induced genes in human epithelial cells. J Dairy Sci 2010; 93:4526-34. [DOI: 10.3168/jds.2010-3274] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 06/11/2010] [Indexed: 12/12/2022]
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Ishikawa F, Ishikawa B, Sugamata J, Ikeda K, Nakamura M, Muraki J, Sato M, Harada H, Saito Y. P6-16 Silent epileptic EEG areal seizure — long term EEG observation of repeated silent seizure in clinical environment. Clin Neurophysiol 2010. [DOI: 10.1016/s1388-2457(10)60564-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Sakata O, Shimada T, Ishikawa F, Ishikawa B, Harada H, Saito Y. P24-17 Combination use of directed information and directed coherence for EEG analysis. Clin Neurophysiol 2010. [DOI: 10.1016/s1388-2457(10)61014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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