Details of the Researcher

PHOTO

Nami Haruta
Section
Institute for Excellence in Higher Education
Job title
Associate Professor
Degree

Committee Memberships 1

  • 日本遺伝学会　評議員

    2017/04 - 2021/03

Research Areas 3

  • Life sciences / Evolutionary biology / C.elegans

  • Life sciences / Molecular biology /

  • Life sciences / Cell biology / Microtubule, centrosome, Cytokinesis

Awards 2

  1. Best Paper賞（第82回大会）

    2010/09　日本遺伝学会

  2. Best Paper賞（第78回大会）

    2006/10　日本遺伝学会

Papers 28

  1. Active and unusually expanded PIF/Harbinger transposable elements in the Caenorhabditis inopinata genome

    Kazuki Sato, Xiaodan Jin, Shun Oomura, Kazuma Kawahara, Simo Sun, Akemi Yoshida, Nami Haruta, Asako Sugimoto, Taisei Kikuchi

    2026/05/29

    DOI： 10.64898/2026.05.26.728016 　

  2. A Fluorescent Dauer Marker in Caenorhabditis inopinata Enables Comparative Analysis of Dauer-Inducing Mechanisms

    Ryo Iitsuka, Shun Oomura, Nami Haruta, Asako Sugimoto

    2026/04/09

    DOI： 10.64898/2026.04.06.716796 　

  3. Application of the auxin-inducible degron 2 (AID2) system to analyze stage-specific roles of the histone variant H2A.Z during development of Caenorhabditis elegans International-journal Invited

    Natsumi Horii, Saho Kitagawa, Yukako Oma, Nami Haruta, Asako Sugimoto, T Masato Kanemaki, Masahiko Harata

    Bioscience, Biotechnology, and Biochemistry　2026/02/23

    DOI： 10.1093/bbb/zbaf200 　

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    Multiple roles of the evolutionarily conserved histone variant H2A.Z in development have been proposed. However, conventional H2A.Z knockouts cause embryonic lethality. Here, we developed a transient depletion system for H2A.Z in Caenorhabditis elegans using an auxin-inducible degron and demonstrated its contribution to germline differentiation at early developmental stages. This system can be applied to investigate temporal protein functions during development.

  4. Programmed DNA elimination was present in the last common ancestor of Caenorhabditis nematodes

    Lewis Stevens, Simo Sun, Nami Haruta, Leyun Xiao, Naoki Uwatoko, Manuela Kieninger, Kazuki Sato, Akemi Yoshida, Dominic Absolon, Joanna Collins, Asako Sugimoto, Taisei Kikuchi, Mark Blaxter

    2025/10/24

    DOI： 10.1101/2025.10.23.681605 　

  5. Microparticle Bombardment as a Method for Transgenesis in Auanema and Tokorhabditis International-journal

    Tatsuya Yamashita, Andre Pires-daSilva, Shun Oomura, Taichi Kusano, Nami Haruta, Mayu Hasumi, Taisei Kikuchi, Sally Adams, Asako Sugimoto, Ryoji Shinya

    microPublication Biology　2025　2025

    Publisher: microPublication Biology

    DOI： 10.17912/MICROPUB.BIOLOGY.001585 　

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    Functional gene analysis tools in Caenorhabditis elegans are often ineffective in other nematodes due to differences in gonadal morphology and transgene silencing. Here, we established a method to generate stable transgenic lines in the nematodes Auanema freiburgense and Tokorhabditis tufae using microparticle bombardment coupled with hygromycin B selection. Despite using non-codon-optimized GFP, transgenic strains expressing fluorescent markers were obtained in both species. Additionally, an Auanema codon-optimized RFP construct showed robust expression in all tissues. This method will be valuable for future studies into the unusual sex determination, viviparity, and stress resistance in Auanema and Tokorhabditis .

  6. Evolutionary changes of noncoding elements associated with transition of sexual mode in Caenorhabditis nematodes

    Katsunori Tamagawa, Mehmet Dayi, Simo Sun, Rikako Hata, Taisei Kikuchi, Nami Haruta, Asako Sugimoto, Takashi Makino

    Science Advances　10　(37)　2024/09/13

    Publisher: American Association for the Advancement of Science (AAAS)

    DOI： 10.1126/sciadv.adn9913 　

    eISSN： 2375-2548

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    The transition of the sexual mode occurs widely in animal evolution. In Caenorhabditis nematodes, androdioecy, a sexual polymorphism composed of males and hermaphrodites having the ability to self-fertilize, has evolved independently multiple times. While the modification of noncoding regulatory elements likely contributed to the evolution of hermaphroditism, little is known about these changes. Here, we conducted a genome-wide analysis of conserved noncoding elements (CNEs) focusing on the evolution of hermaphroditism in Caenorhabditis nematodes. We found that, in androdioecious nematodes, mutations rapidly accumulated in CNEs’ neighboring genes associated with sexual traits. Expression analysis indicate that the identified CNEs are involved in spermatogenesis in hermaphrodites and associated with the transition of gene expression from dioecious to androdioecious nematodes. Last, genome editing of a CNE neighboring laf-1 resulted in a change in its expression in the gonadal region undergoing spermatogenesis. Our bioinformatic and experimental analyses highlight the importance of CNEs in gene regulation associated with the development of hermaphrodites.

  7. The impact of differential transposition activities of autonomous and non-autonomous hAT transposable elements on genome architecture and gene expression in Caenorhabditis inopinata Peer-reviewed

    Ryuhei Hatanaka, Katsunori Tamagawa, Nami Haruta, Asako Sugimoto

    GENETICS　2024/04/05

    Publisher: Oxford University Press (OUP)

    DOI： 10.1093/genetics/iyae052 　

    eISSN： 1943-2631

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    Abstract Transposable elements (TEs) are DNA sequences capable of moving within genomes and significantly influence genomic evolution. The nematode Caenorhabditis inopinata exhibits a much higher TE copy number than its sister species, C. elegans. In this study, we identified a novel autonomous TE belonging to the hAT superfamily from a spontaneous TE-insertion mutant in C. inopinata and named this transposon Ci-hAT1. Further bioinformatic analyses uncovered three additional autonomous hAT elements—Ci-hAT2, Ci-hAT3, and Ci-hAT4—along with over 1,000 copies of two non-autonomous miniature inverted-repeat transposable elements (MITEs), mCi-hAT1 and mCi-hAT4, likely derived from Ci-hAT1 and Ci-hAT4 through internal deletion. We tracked at least three sequential transpositions of Ci-hAT1 over several years. However, the transposition rates of the other three autonomous hAT elements were lower, suggesting varying activity levels. Notably, the distribution patterns of the two MITE families differed significantly: mCi-hAT1 was primarily located in the chromosome arms, a pattern observed in the TEs of other Caenorhabditis species, whereas mCi-hAT4 was more evenly distributed across chromosomes. Additionally, interspecific transcriptome analysis indicated that C. inopinata genes with upstream or intronic these MITE insertions tend to be more highly expressed than their orthologous genes in C. elegans. These findings highlight the significant role of de-silenced TEs in driving the evolution of genomes and transcriptomes, leading to species-specific genetic diversity.

  8. A germline-specific role for unconventional components of the γ-tubulin complex in Caenorhabditis elegans. International-journal

    Nami Haruta, Eisuke Sumiyoshi, Yu Honda, Masahiro Terasawa, Chihiro Uchiyama, Mika Toya, Yukihiko Kubota, Asako Sugimoto

    Journal of cell science　136　(13)　2023/07/01

    DOI： 10.1242/jcs.260922 　

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    The γ-tubulin complex (γTuC) is a widely conserved microtubule nucleator, but some of its components, namely GCP4, GCP5 and GCP6 (also known as TUBGCP4, TUBGCP5 and TUBGCP6, respectively), have not been detected in Caenorhabditis elegans. Here, we identified two γTuC-associated proteins in C. elegans, GTAP-1 and GTAP-2, for which apparent orthologs were detected only in the genus Caenorhabditis. GTAP-1 and GTAP-2 were found to localize at centrosomes and the plasma membrane of the germline, and their centrosomal localization was interdependent. In early C. elegans embryos, whereas the conserved γTuC component MZT-1 (also known as MOZART1 and MZT1) was essential for the localization of centrosomal γ-tubulin, depletion of GTAP-1 and/or GTAP-2 caused up to 50% reduction of centrosomal γ-tubulin and precocious disassembly of spindle poles during mitotic telophase. In the adult germline, GTAP-1 and GTAP-2 contributed to efficient recruitment of the γTuC to the plasma membrane. Depletion of GTAP-1, but not of GTAP-2, severely disrupted both the microtubule array and the honeycomb-like structure of the adult germline. We propose that GTAP-1 and GTAP-2 are unconventional components of the γTuC that contribute to the organization of both centrosomal and non-centrosomal microtubules by targeting the γTuC to specific subcellular sites in a tissue-specific manner.

  9. C. elegans ATG-5 mutants associated with ataxia. International-journal Peer-reviewed

    Azusa Yugeta, Hiroki Arai, Daiki Takahashi, Nami Haruta, Asako Sugimoto, Hirokazu Arimoto

    microPublication biology　2023　2023

    DOI： 10.17912/micropub.biology.000792 　

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    Intercellular cleaning via autophagy is crucial for maintaining cellular homeostasis, and impaired autophagy has been associated with the accumulation of protein aggregates that can contribute to neurological diseases. Specifically, the loss-of-function mutation in the human autophagy-related gene 5 (ATG5) at E122D has been linked to the pathogenesis of spinocerebellar ataxia in humans. In this study, we generated two homozygous C. elegans strains with mutations (E121D and E121A) at positions corresponding to the human ATG5 ataxia mutation to investigate the effects of ATG5 mutations on autophagy and motility. Our results showed that both mutants exhibited a reduction in autophagy activity and impaired motility, suggesting that the conserved mechanism of autophagy-mediated regulation of motility extends from C. elegans to humans.

  10. The auxin-inducible degron 2 (AID2) system enables controlled protein knockdown during embryogenesis and development in Caenorhabditis elegans. International-journal Peer-reviewed

    Takefumi Negishi, Saho Kitagawa, Natsumi Horii, Yuka Tanaka, Nami Haruta, Asako Sugimoto, Hitoshi Sawa, Ken-Ichiro Hayashi, Masahiko Harata, Masato T Kanemaki

    Genetics　220　(2)　2022/02/04

    DOI： 10.1093/genetics/iyab218 　

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    Targeted protein degradation using the auxin-inducible degron (AID) system is garnering attention in the research field of Caenorhabditis elegans, because of the rapid and efficient target depletion it affords, which can be controlled by treating the animals with the phytohormone auxin. However, the current AID system has drawbacks, i.e., leaky degradation in the absence of auxin and the requirement for high auxin doses. Furthermore, it is challenging to deplete degron-fused proteins in embryos because of their eggshell, which blocks auxin permeability. Here, we apply an improved AID2 system utilizing AtTIR1(F79G) and 5-phenyl-indole-3-acetic acid (5-Ph-IAA) to C. elegans and demonstrated that it confers better degradation control vs the previous system by suppressing leaky degradation and inducing sharp degradation using 1,300-fold lower 5-Ph-IAA doses. We successfully degraded the endogenous histone H2A.Z protein fused to an mAID degron and disclosed its requirement in larval growth and reproduction, regardless of the presence of maternally inherited H2A.Z molecules. Moreover, we developed an eggshell-permeable 5-Ph-IAA analog, 5-Ph-IAA-AM, that affords an enhanced degradation in laid embryos. Our improved system will contribute to the disclosure of the roles of proteins in C. elegans, in particular those that are involved in embryogenesis and development, through temporally controlled protein degradation.

  11. Transgenesis of the gonochoristic nematode Caenorhabditis inopinata by microparticle bombardment with hygromycin B selection. International-journal Peer-reviewed

    Shun Oomura, Kenji Tsuyama, Nami Haruta, Asako Sugimoto

    microPublication biology　2022　2022

    DOI： 10.17912/micropub.biology.000564 　

  12. Expression Patterns and Levels of All Tubulin Isotypes Analyzed in GFP Knock-In C. elegans Strains. Peer-reviewed

    Kei Nishida, Kenta Tsuchiya, Hiroyuki Obinata, Shizuka Onodera, Yu Honda, Yen-Cheng Lai, Nami Haruta, Asako Sugimoto

    Cell structure and function　46　(1)　51-64　2021/06/30

    DOI： 10.1247/csf.21022 　

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    Most organisms have multiple α- and β-tubulin isotypes that likely contribute to the diversity of microtubule (MT) functions. To understand the functional differences of tubulin isotypes in Caenorhabditis elegans, which has nine α-tubulin isotypes and six β-tubulin isotypes, we systematically constructed null mutants and GFP-fusion strains for all tubulin isotypes with the CRISPR/Cas9 system and analyzed their expression patterns and levels in adult hermaphrodites. Four isotypes-α-tubulins TBA-1 and TBA-2 and β-tubulins TBB-1 and TBB-2-were expressed in virtually all tissues, with a distinct tissue-specific spectrum. Other isotypes were expressed in specific tissues or cell types at significantly lower levels than the broadly expressed isotypes. Four isotypes (TBA-5, TBA-6, TBA-9, and TBB-4) were expressed in different subsets of ciliated sensory neurons, and TBB-4 was inefficiently incorporated into mitotic spindle MTs. Taken together, we propose that MTs in C. elegans are mainly composed of four broadly expressed tubulin isotypes and that incorporation of a small amount of tissue-specific isotypes may contribute to tissue-specific MT properties. These newly constructed strains will be useful for further elucidating the distinct roles of tubulin isotypes.Key words: tubulin isotypes, microtubules, C. elegans.

  13. Centrosome maturation requires phosphorylation-mediated sequential domain interactions of SPD-5 International-journal

    Momoe Nakajo, Hikaru Kano, Kenji Tsuyama, Nami Haruta, Asako Sugimoto

    Journal of cell science　135　(8)　2021/05/20

    Publisher: Cold Spring Harbor Laboratory

    DOI： 10.1101/2021.05.20.444955 　

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    <title>Abstract</title>Centrosomes consist of two centrioles and surrounding pericentriolar material (PCM). PCM expands during mitosis in a process called centrosome maturation, in which PCM scaffold proteins play pivotal roles to recruit other centrosomal proteins. In <italic>C. elegans</italic>, the scaffold protein SPD-5 forms PCM scaffold in a PLK-1 phosphorylation-dependent manner. However, how phosphorylation of SPD-5 promotes PCM scaffold assembly is unclear. Here, we identified three functional domains of SPD-5 through <italic>in vivo</italic> domain analyses, and propose that sequential domain interactions of SPD-5 are required for mitotic PCM scaffold assembly. Firstly, SPD-5 is targeted to centrioles through direct interaction between its centriole localization (CL) domain and a centriolar protein PCMD-1. Then, intra- and inter-molecular interaction between SPD-5 phospho-regulated multimerization (PReM) domain and the PReM association (PA) domain is triggered by phosphorylation by PLK-1, which leads to PCM scaffold expansion. Our findings suggest that the sequential domain interactions of scaffold proteins mediated by Polo/PLK-1 phosphorylation is an evolutionarily conserved mechanism of PCM scaffold assembly.

  14. Tubulin isotype substitution revealed that isotype combination modulates microtubule dynamics in C. elegans embryos Peer-reviewed

    Yu Honda, Kenta Tsuchiya, Eisuke Sumiyoshi, Nami Haruta, Asako Sugimoto

    JOURNAL OF CELL SCIENCE　130　(9)　1652-1661　2017/05

    DOI： 10.1242/jcs.200923 　

    ISSN： 0021-9533

    eISSN： 1477-9137

  15. The PAF1 complex is involved in embryonic epidermal morphogenesis in Caenorhabditis elegans Peer-reviewed

    Yukihiko Kubota, Kenji Tsuyama, Yusuke Takabayashi, Nami Haruta, Rika Maruyama, Naoko Iida, Asako Sugimoto

    DEVELOPMENTAL BIOLOGY　391　(1)　43-53　2014/07

    DOI： 10.1016/j.ydbio.2014.04.002 　

    ISSN： 0012-1606

    eISSN： 1095-564X

  16. Chronic low-dose ultraviolet-induced mutagenesis in nucleotide excision repair-deficient cells Peer-reviewed

    Nami Haruta, Yoshino Kubota, Takashi Hishida

    NUCLEIC ACIDS RESEARCH　40　(17)　8406-8415　2012/09

    DOI： 10.1093/nar/gks580 　

    ISSN： 0305-1048

    eISSN： 1362-4962

  17. Srs2 Plays a Critical Role in Reversible G(2) Arrest upon Chronic and Low Doses of UV Irradiation via Two Distinct Homologous Recombination-Dependent Mechanisms in Postreplication Repair-Deficient Cells Peer-reviewed

    Takashi Hishida, Yoshihiro Hirade, Nami Haruta, Yoshino Kubota, Hiroshi Iwasaki

    MOLECULAR AND CELLULAR BIOLOGY　30　(20)　4840-4850　2010/10

    DOI： 10.1128/MCB.00453-10 　

    ISSN： 0270-7306

    eISSN： 1098-5549

  18. Disassembly of Escherichia coli RecA E38K/Delta C17 Nucleoprotein Filaments Is Required to Complete DNA Strand Exchange Peer-reviewed

    Rachel L. Britt, Nami Haruta, Shelley L. Lusetti, Sindhu Chitteni-Pattu, Ross B. Inman, Michael M. Cox

    JOURNAL OF BIOLOGICAL CHEMISTRY　285　(5)　3211-3226　2010/01

    DOI： 10.1074/jbc.M109.028951 　

    ISSN： 0021-9258

  19. Reconstitution of DNA strand exchange mediated by Rhp51 recombinase and two mediators Peer-reviewed

    Yumiko Kurokawa, Yasuto Murayama, Nami Haruta-Takahashi, Itaru Urabe, Hiroshi Iwasaki

    PLOS BIOLOGY　6　(4)　836-848　2008/04

    DOI： 10.1371/journal.pbio.0060088 　

    ISSN： 1544-9173

  20. Fission yeast Swi5 protein, a novel DNA recombination mediator Invited Peer-reviewed

    Nami Haruta, Yufuko Akamatsu, Yasuhiro Tsutsui, Yumiko Kurokawa, Yasuto Murayama, Benoit Arcangioli, Hiroshi Iwasaki

    DNA REPAIR　7　(1)　1-9　2008/01

    DOI： 10.1016/j.dnarep.2007.07.004 　

    ISSN： 1568-7864

  21. Recombination mediators Invited Peer-reviewed

    Nami Haruta-Takahashi, Hiroshi Iwasaki

    SEIKAGAKU　79　(5)　449-453　2007/05

    ISSN： 0037-1017

  22. The Swi5-Sfr1 complex stimulates Rhp51/Rad51- and Dmc1-mediated DNA strand exchange in vitro. International-journal Peer-reviewed

    Nami Haruta, Yumiko Kurokawa, Yasuto Murayama, Yufuko Akamatsu, Satoru Unzai, Yasuhiro Tsutsui, Hiroshi Iwasaki

    Nature structural & molecular biology　13　(9)　823-30　2006/09

    DOI： 10.1038/nsmb1136 　

    ISSN： 1545-9993

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    Nucleoprotein filaments made up of Rad51 or Dmc1 recombinases, the core structures of recombination, engage in ATP-dependent DNA-strand exchange. The ability of recombinases to form filaments is enhanced by recombination factors termed 'mediators'. Here, we show that the Schizosaccharomyces pombe Swi5-Sfr1 complex, a conserved eukaryotic protein complex, at substoichiometric concentrations stimulates strand exchange mediated by Rhp51 (the S. pombe Rad51 homolog) and Dmc1 on long DNA substrates. Reactions mediated by both recombinases are completely dependent on Swi5-Sfr1, replication protein A (RPA) and ATP, although RPA inhibits the reaction when it is incubated with single-stranded DNA (ssDNA) before the recombinase. The Swi5-Sfr1 complex overcomes, at least partly, the inhibitory effect of RPA, representing a novel class of mediator. Notably, the Swi5-Sfr1 complex preferentially stimulates the ssDNA-dependent ATPase activity of Rhp51, and it increases the amounts of Dmc1 bound to ssDNA.

  23. The single-stranded DNA-binding protein of Deinococcus radiodurans Peer-reviewed

    JM Eggington, N Haruta, EA Wood, MM Cox

    BMC MICROBIOLOGY　4　2　2004/01

    DOI： 10.1186/1471-2180-4-2 　

    ISSN： 1471-2180

  24. A DNA pairing-enhanced conformation of bacterial RecA proteins Peer-reviewed

    N Haruta, XN Yu, SX Yang, EH Egelman, MM Cox

    JOURNAL OF BIOLOGICAL CHEMISTRY　278　(52)　52710-52723　2003/12

    DOI： 10.1074/jbc.M308563200 　

    ISSN： 0021-9258

  25. Time-resolved UV resonance Raman investigation of protein folding using a rapid mixer: Characterization of kinetic folding intermediates of apomyoglobin Peer-reviewed

    N Haruta, T Kitagawa

    BIOCHEMISTRY　41　(21)　6595-6604　2002/05

    DOI： 10.1021/bi012027g 　

    ISSN： 0006-2960

  26. Time-resolved resonance Raman study on ultrafast structural relaxation and vibrational cooling of photodissociated carbonmonoxy myoglobin Peer-reviewed

    T Kitagawa, N Haruta, Y Mizutani

    BIOPOLYMERS　67　(4-5)　207-213　2002

    DOI： 10.1002/bip.10096 　

    ISSN： 0006-3525

  27. Protein conformation change of myoglobin upon ligand binding probed by ultraviolet resonance Raman Spectroscopy Peer-reviewed

    N Haruta, M Aki, S Ozaki, Y Watanabe, T Kitagawa

    BIOCHEMISTRY　40　(23)　6956-6963　2001/06

    DOI： 10.1021/bi002640k 　

    ISSN： 0006-2960

  28. UV resonance Raman detection of a ligand vibration on ferric nitrosyl heme proteins Peer-reviewed

    T Tomita, N Haruta, M Aki, T Kitagawa, M Ikeda-Saito

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY　123　(11)　2666-2667　2001/03

    DOI： 10.1021/ja001431k 　

    ISSN： 0002-7863

Show all ︎Show first 5

Misc. 5

  1. 線虫の生殖システム転換への非コード保存領域の貢献

    玉川克典, DAYI Mehmet, 孫思墨, 菊地泰生, 春田奈美, 杉本亜砂子, 牧野能士

    日本遺伝学会大会プログラム要旨集(CD-ROM)　95th　2023

  2. 線虫近縁種をモデル系とした種に固有の体サイズを実現する遺伝的制御機構の解明

    大村駿, 春田奈美, 玉川克典, 牧野能士, 杉本亜砂子

    日本遺伝学会大会プログラム要旨集(CD-ROM)　95th　2023

  3. Chronic low-dose UV irradiation (CLUV)-induced mutagenesis in yeast

    Nami Haruta, Yoshino Kubota, Takashi Hishida

    GENES & GENETIC SYSTEMS　85　(6)　436-436　2010/12

    ISSN： 1341-7568

    eISSN： 1880-5779

  4. Molecular analysis of activation of Rhp51-dependent DNA strand exchange by the Swi5-Sfr1 complex

    Yasuto Murayama, Yumiko Kurokawa, Nami Haruta, Hiroshi Iwasaki

    GENES & GENETIC SYSTEMS　82　(6)　544-544　2007/12

    ISSN： 1341-7568

    eISSN： 1880-5779

  5. The activation mechanism of SpRad51-mediated DNA strand exchange reaction by Swi5-Sfr1 complex in Schizosaccharomyces pombe

    Nami Haruta, Yumiko Kurokawa, Yasuto Murayama, Hiroshi Iwasaki, Takashi Hishida

    GENES & GENETIC SYSTEMS　81　(6)　410-410　2006/12

    ISSN： 1341-7568

    eISSN： 1880-5779

Research Projects 6

  1. Study of tissue-specific Microtubule organization center

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: Tohoku University

    2023/04/01 - 2026/03/31

  2. Regulation of tissue-specific microtubule arrays

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: Tohoku University

    2020/04/01 - 2023/03/31

  3. The roles of the component proteins in the assembly and the recruitment of C. elegans &gamma;-tubulin complex

    HARUTA Nami, SUGIMOTO Asako, UCHIYAMA Chihiro, NAKAJO Momoe, SAITO Yuki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: Tohoku University

    2016/04/01 - 2019/03/31

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    The γ-tubulin complex (γTuC) is a widely conserved microtubule (MT) nucleator, which serves as a template for MTs. To understand the molecular mechanism of the assembly and recruitment of γTuC, we characterized several components of γTuC; MOZART1, GTAP-1 and -2. We demonstrated that the interaction between MOZART1 and N-terminus of GIP-1 is essential for the centrosomal recruitment of γTuC, while GTAP-1 and GTAP-2 are not essential but required for efficient recruitment of γTuC. Moreover, GTAP-1 plays a crucial role in germline through controlling the localization of γ-tubulin onto gonad membrane, although GTAP-2 is dispensable. These data strongly indicated that the components of γTuC are likely changed, depending on the cell cycles and types.

  4. Revisiting "the multi-tubulin hypothesis" through comprehensive analysis of tubulin isotypes

    Sugimoto Asako, KUBOTA Yukihiko, HARUTA Nami, HONDA Yu, TSUCHIYA Kenta, OBINATA Hiroyuki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2015/04/01 - 2018/03/31

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    In this study, we tested the "multi-tubulin hypothesis" in which multiple tubulin isotypes contribute to the diversity of microtubule dynamics, using the nematode C. elegans as a model system. Using genome editing, all tubulin isotype genes (9 alpha and 6 beta genes) were systematically knocked out and tagged with GFP, and their expression patterns and loss-of-function phenotypes were analyzed. Each isotypes were expressed in specific cell types, and ectopic expression experiments proved that composition of tubulin isotypes contribute to the diversity of microtubule dynamics.

  5. Rad51のアクセサリータンパク質群による相同組換え反応の制御メカニズム

    高橋 奈美

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費

    Category: 特別研究員奨励費

    2008 - 2011

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    今年度より線虫C.elegansをモデル生物として用いて、rad51に関連するタンパク質の一つとしてBRCA1のホモログであるBRC-1についての解析を進めてきた。BRCA1は、ヒトの乳がん原因遺伝子の一つとしてBRCA2とともに同定されたが、BRCA2がRad51のメディエーター機能が明らかにされる一方、BRCA1の役割ははっきりしていない。しかし、Rad51と直接相互作用することから、相同組換えに関与していることが示唆されている。そこで私は、BRCA1/BRC-1の機能を明らかにするために、BRC-1とその結合タンパク質であるBARD1/BRD-1、さらにヒトで相互作用が確認されたOLA1/OLA-1について解析を行った。成虫になる前のL4幼虫の段階でRNAiソーキング法を用いて、それぞれのmRNAを破壊してその表現系解析を行った。その結果、RNAi処理した成虫が産んだ卵の致死率は0%で、ほとんど影響はなかった。しかし、その産卵数は、BRC-1,BRD-1,0LA-1がいずれにおいてもコントロールに比べて減少していたことから、卵形成過程で何らかの影響を及ぼしていることが示唆された。現在、そのメカニズムについてRad-51の表現系とも比較しながら詳細に検討を進めている。 また線虫を用いて、染色体が正しく分配されるのに必要な紡錘体微小管形成についても新たな研究を展開した。Γ-tubulinは、微小管形成に必須のタンパク質であるが、GCPタンパク質と呼ばれるいくつかのタンパク質と複合体を形成する。当研究室で同定された新規タンパク質GTAP-1とGTAP-2が、Y-tubulinと直接結合することをYeast two-hybrid法やバキュロウィルス発現系を用いた再構成系で示し、またショ糖密度勾配法を用いて、これらのタンパク質がY-tubulin複合体の新規構成因子であることを示した。

  6. 分裂酵母におけるRad51依存的な遺伝的組換え反応の分子機構

    高橋 奈美

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費

    Category: 特別研究員奨励費

    2005 - 2007

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    分裂酵母における相同組換え反応のメカニズムを解明するために、Rad51のアクセサリータンパク質であるSwi5-SfrlとRad55-Rad57の複合体について解析を行った。相同組換えの中心的な役割を果たすRad51は、DNA鎖交換反応を行う。Sfrl/Swi5複合体の存在下では、Rad51タンパク質のATP加水分解活性および鎖交換反応活性が顕著に促進されることを、試験管内再構成による反応系でこれまで示してきた。本年度はRad51のもう一つのアクセサリータンパク質であるRad55-Rad57に焦点をあてて研究を進めた。Rad55,Rad57は単独での発現および大腸菌での発現は、不溶性画分になったが、昆虫細胞において共発現することで可溶性になった。そこで、数段階のクロマトグラフィーを組み合わせて複合体として精製することができた。精製したタンパク質複合体は、免疫沈降法によってRad51と物理的な相互作用があることを示した。しかし、予想されたATP加水分解活性やDNA結合活性は認められなかった。 この精製したRad55-Rad57をRad51のDNA鎖交換反応に加えたが、反応の顕著な促進は見られなかった。しかし、Swi5-Sfrl存在下でのRad51の反応は、Swi5-Sfrlの等量のRad55-Rad57によって阻害を受けたことから、二つのアクセサリータンパク質が拮抗してRad51に働いている可能性も示唆された。

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