研究者業績

知花 博治

チバナ ヒロジ  (Hiroji Chibana)

基本情報

所属
千葉大学 真菌医学研究センター 准教授 (准教授)
学位
博士(医学)(名古屋大学)
Ph. D. of Medical Science

J-GLOBAL ID
200901052291283800
researchmap会員ID
5000004163

論文

 124
  • Shigeki Aoki, Michie Morita, Takuya Hirao, Masashi Yamaguchi, Reika Shiratori, Megumi Kikuya, Hiroji Chibana, Kousei Ito
    Oncotarget 8(55) 94271-94285 2017年11月1日  査読有り
    © Aoki et al. Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Treatments include glucocorticoids (GCs) such as dexamethasone (Dex) and prednisolone, which may be of value when used alongside cytotoxic anti-cancer drugs. To predict therapeutic efficacy of GCs, their activity against ALL cells is usually examined prior to chemotherapy; however, few studies have examined their effects when used in combination with other drugs. The paradox is that cytotoxic anticancer drugs that are effective against proliferating cancer cells show synergistic effects when used with GCs that prevent cell proliferation. To address this point, we investigated intracellular energy metabolism in ALL CCRF-CEM cell clones classified according to their sensitivity to Dex and cytotoxic anti-cancer drugs in bulk cultures of mixed cells. We found that Dex suppressed glycolysis, the most important metabolic system in cancer cells, in cells that were damaged by etoposide (a cytotoxic anticancer drug), and the cells showed a concomitant increase in mitochondrial oxidative phosphorylation. Furthermore, autophagy, an intracellular bulk degradation system, regulated mitochondrial viability. We also found that mitochondria, whose function is enhanced by Dex, were susceptible to anti-cancer drugs that inhibit respiratory complexes (e.g., etoposide and daunorubicin), resulting in increased production of reactive oxygen species and subsequent cytotoxicity. Taken together, the present study points the way toward a more accurate prediction of the sensitivity of ALL cells to the combined action of anti-cancer drugs and GCs, by taking into consideration the shift in intracellular energy metabolism caused by GCs: namely, from glycolysis to mitochondrial oxidative phosphorylation mediated by autophagy.
  • Hiroyuki Yamada, Masashi Yamaguchi, Kiminori Shimizu, Somay Yamagata Murayama, Satoshi Mitarai, Chihiro Sasakawa, Hiroji Chibana
    Microscopy 66(4) 283-294 2017年8月1日  査読有り
    © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. Structome analysis, the quantitative three-dimensional structural analysis of whole cells at the electron microscopic level, of Exophiala dermatitidis (black yeast), Saccharomyces cerevisiae, Mycobacterium tuberculosis (MTB) and Myojin spiral bacteria (MSB) have already been reported. Here, the results of the structome analysis of Escherichia coli cells based on transmission electron microscope observation of serial ultrathin sections was reported, and compared with the data obtained from phase contrast microscopy and scanning electron microscopy. On average, the cells had 0.89 μm in diameter, 2.47 μm in length and 1.16 fl (μm3) in cell volume in the structome analysis. Furthermore, E. coli cells had 26 100 ribosomes per whole cell with density of 2840 per 0.1 fl cytoplasm. The total ribosome number per cell was 15 times larger than that of MTB and about one-eighth of those of the yeast cells above. On the other hand, the ribosome density of E. coli cells are more than 13 times, 4 times, 2.5-times and 1.5-times higher than MSB, MTB, E. dermatitidis and S. cerevisiae, respectively. Finally, our ribosome enumeration data were compared between the structome-analyzed species and the relationship between the ribosome density and the growth rate among these species was discussed.
  • Masashi Yamaguchi, Azusa Takahashi-Nakaguchi, Yuko Aida, Michiyo Sato-Okamoto, Hiroji Chibana
    Microscopy 66(3) 209-211 2017年6月1日  査読有り
    © The Author 2017. Rapid freeze–freeze substitution after glutaraldehyde fixation (CF–FS method) obtained the natural and fine structures of macrophages and engulfed yeast cells. Culturing macrophages on single hole molybdenum grids placed in culture dishes made possible the rapid freezing of cells by the ‘open sandwich method’. This method may be convenient when rapid-freezing cannot be performed immediately, or when a rapid-freezing device is not available in the lab.
  • Ruben T. Bernardo, Diana V. Cunha, Can Wang, Leonel Pereira, Sónia Silva, Sara B. Salazar, Markus S. Schröder, Michiyo Okamoto, Azusa Takahashi-Nakaguchi, Hiroji Chibana, Toshihiro Aoyama, Isabel Sá-Correia, Joana Azeredo, Geraldine Butler, Nuno Pereira Mira
    G3: Genes, Genomes, Genetics 7(1) 1-18 2017年  査読有り
    © 2017 Bernardo et al. To thrive in the acidic vaginal tract, Candida glabrata has to cope with high concentrations of acetic acid. The mechanisms underlying C. glabrata tolerance to acetic acid at low pH remain largely uncharacterized. In this work, the essential role of the CgHaa1 transcription factor (encoded by ORF CAGL0L09339g) in the response and tolerance of C. glabrata to acetic acid is demonstrated. Transcriptomic analysis showed that CgHaa1 regulates, directly or indirectly, the expression of about 75% of the genes activated under acetic acid stress. CgHaa1-activated targets are involved in multiple physiological functions including membrane transport, metabolism of carbohydrates and amino acids, regulation of the activity of the plasma membrane H+-ATPase, and adhesion. Under acetic acid stress, CgHaa1 increased the activity and the expression of the CgPma1 proton pump and contributed to increased colonization of vaginal epithelial cells by C. glabrata. CgHAA1, and two identified CgHaa1-activated targets, CgTPO3 and CgHSP30, are herein demonstrated to be determinants of C. glabrata tolerance to acetic acid. The protective effect of CgTpo3 and of CgHaa1 was linked to a role of these proteins in reducing the accumulation of acetic acid inside C. glabrata cells. In response to acetic acid stress, marked differences were found in the regulons controlled by CgHaa1 and by its S. cerevisiae ScHaa1 ortholog, demonstrating a clear divergent evolution of the two regulatory networks. The results gathered in this study significantly advance the understanding of the molecular mechanisms underlying the success of C. glabrata as a vaginal colonizer.
  • Masashi Yamaguchi, Hiroyuki Yamada, Kimitaka Higuchi, Yuta Yamamoto, Shigeo Arai, Kazuyoshi Murata, Yuko Mori, Hiromitsu Furukawa, Mohammad Shorif Uddin, Hiroji Chibana
    Microscopy 65(4) 363-369 2016年8月1日  査読有り
    © The Author 2016. Structome analysis is a useful tool for identification of unknown microorganisms that cannot be cultured. In 2012, we discovered a unique deep-sea microorganism with a cell structure intermediate between those of prokaryotes and eukaryotes and described its features using freeze-substitution electron microscopy and structome analysis (quantitative and three-dimensional structural analysis of a whole cell at the electron microscopic level). We named it Myojin parakaryote. Here we describe, using serial ultrathin sectioning and high-voltage electron microscopy tomography of freeze-substituted specimens, the structome analysis and 3D reconstruction of another unique spiral bacteria, found in the deep sea off the coast of Japan. The bacteria, which is named as ‘Myojin spiral bacteria’ after the discovery location and their morphology, had a total length of 1.768 ± 0.478 µm and a total diameter of 0.445 ± 0.050 µm, and showed either clockwise or counter-clockwise spiral. The cells had a cell surface membrane, thick fibrous layer, ribosomes and inner fibrous structures (most likely DNA). They had no flagella. The bacteria had 322 ± 119 ribosomes per cell. This ribosome number is only 1.2% of that of Escherichia coli and 19.3% of Mycobacterium tuberculosis and may reflect a very slow growth rate of this organismin the deep sea.
  • Yutaka Tanaka, Masato Sasaki, Fumie Ito, Toshio Aoyama, Michiyo Sato-Okamoto, Azusa Takahashi-Nakaguchi, Hiroji Chibana, Nobuyuki Shibata
    PLoS ONE 11(8) e0161371 2016年8月  査読有り
    © 2016 Tanaka et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The maintenance of cell wall integrity in fungi is required for normal cell growth, division, hyphae formation, and antifungal tolerance. We observed that endoplasmic reticulum stress regulated cell wall integrity in Candida glabrata, which possesses uniquely evolved mechanisms for unfolded protein response mechanisms. Tetracycline-mediated suppression of KRE5, which encodes a predicted UDP-glucose: glycoprotein glucosyltransferase localized in the endoplasmic reticulum, significantly increased cell wall chitin content and decreased cell wall p-1,6-glucan content. KRE5 repression induced endoplasmic reticulum stressrelated gene expression and MAP kinase pathway activation, including Slt2p and Hog1p phosphorylation, through the cell wall integrity signaling pathway. Moreover, the calcineurin pathway negatively regulated cell wall integrity, but not the reduction of p-1,6-glucan content. These results indicate that KRE5 is required for maintaining both endoplasmic reticulum homeostasis and cell wall integrity, and that the calcineurin pathway acts as a regulator of chitin-glucan balance in the cell wall and as an alternative mediator of endoplasmic reticulum stress in C. glabrata.
  • Kouyuki Hirayasu, Fumiji Saito, Tadahiro Suenaga, Kyoko Shida, Noriko Arase, Keita Oikawa, Toshifumi Yamaoka, Hiroyuki Murota, Hiroji Chibana, Ichiro Nakagawa, Tomoko Kubori, Hiroki Nagai, Yuji Nakamaru, Ichiro Katayama, Marco Colonna, Hisashi Arase
    Nature Microbiology 1(6) 16054-16054 2016年4月  査読有り
    © 2016 Macmillan Publishers Limited. All rights reserved. Microbial proteases degrade a variety of host proteins 1-3. However, it has remained largely unknown why microorganisms have evolved to acquire such proteases and how the host responds to microbially degraded products. Here, we have found that immunoglobulins disrupted by microbial pathogens are specifically detected by leukocyte immunoglobulin-like receptor A2 (LILRA2), an orphan activating receptor expressed on human myeloid cells. Proteases from Mycoplasma hyorhinis, Legionella pneumophila, Streptococcus pneumonia and Candida albicans cleaved the N-terminus of immunoglobulins. Identification of the immunoglobulin-cleaving protease from L. pneumophila revealed that the protease is conserved across some bacteria including Vibrio spp. and Pseudomonas aeruginosa. These microbially cleaved immunoglobulins but not normal immunoglobulins stimulated human neutrophils via LILRA2. In addition, stimulation of primary monocytes via LILRA2 inhibited the growth of L. pneumophila. When mice were infected with L. pneumophila, immunoglobulins were cleaved and recognized by LILRA2. More importantly, cleaved immunoglobulins were detected in patients with bacterial infections and stimulated LILRA2-expressing cells. Our findings demonstrate that LILRA2 is a type of innate immune receptor in the host immune system that detects immunoglobulin abnormalities caused by microbial pathogens.
  • Stepanova AA, Yamaguchi M, Chibana H, Vasilyeva NV
    Problems in Medical Mycology 18(3) 24-29 2016年  招待有り
  • Stepanova A, Vasilyeva N, Yamaguchi M, Chibana H
    Problems in Medical Mycology 18(4) 47-52 2016年  招待有り
  • Stepanova AA, Vasilyeva NV, Yamaguchi M, Chibana H, Bosak IA
    Problems in Medical Mycology 18 20-25 2016年  招待有り
  • Masashi Yamaguchi, Azusa Takahashi, Yuko Aida, Hiroji Chibana
    Microscopy 65 i26 2016年  査読有り
    © 2016, Oxford University Press. All rights reserved. Introduction: It is not easy to observe fine structures of yeast cells engulfed by macrophages by chemical fixation electron microscopy, because the cytoplasm of yeast cells became dark by conventional chemical fixation. Here, we applied rapid freeze-freeze substitution method to overcome this situation. Materials and Methods: Human macrophages were cultured in plastic Petri dishes, yeast cells (Saccharomyces cerevisiae, Candida glabrata, Candida albicans) were fed, and fixed with 2.5% glutaraldehyde. They were then rapidly frozen with melting propane, freeze-substituted in acetone containing 2% OsO4 at -80°C for 2 days, and embedded in epoxy resin. Ultrathin sections were cut to 70 nm thickness, stained with uranyl acetate and lead citrate, covered with Super Support Film (Nisshin EM Co. Ltd., Tokyo), and observed by JEM-1400 electron microscope (JEOL Ltd., Tokyo) at 100 kV. Conventional chemical fixation was also done for comparison. Results and Discussion: Not only ultrastructures of macrophages but also yeast cell structures such as nucleus, mitochondria, ER, ribosomes, and cell wall were clearly observed by freeze-substitution method. Thus, freeze-substitution method was found to be superior to conventional chemical fixation method for observing macrophages and yeast cells at the same time.
  • Pedro Pais, Catarina Costa, Carla Pires, Kiminori Shimizu, Hiroji Chibana, Miguel C. Teixeira
    Molecular and Cellular Proteomics 15(1) 57-72 2016年1月  査読有り
    © 2016 by The American Society for Biochemistry and Molecular Biology, Inc. Azoles are widely used antifungal drugs. This family of compounds includes triazoles, mostly used in the treatment of systemic infections, and imidazoles, such as clotrimazole, often used in the case of superficial infections. Candida glabrata is the second most common cause of candidemia worldwide and presents higher levels of intrinsic azole resistance when compared with Candida albicans, thus being an interesting subject for the study of azole resistance mechanisms in fungal pathogens. Since resistance often relies on the action of membrane transporters, including drug efflux pumps from the ATPbinding cassette family or from the Drug:H+ antiporter (DHA)1 family, an iTRAQ-based membrane proteomics analysis was performed to identify all the membraneassociated proteins whose abundance changes in C. glabrata cells exposed to the azole drug clotrimazole. Proteins found to have significant expression changes in this context were clustered into functional groups, namely: glucose metabolism, oxidative phosphorylation, mitochondrial import, ribosome components and translation machinery, lipid metabolism, multidrug resistance transporters, cell wall assembly, and stress response, comprising a total of 37 proteins. Among these, the DHA transporter CgTpo1-2 (ORF CAGL0E03674g) was identified as overexpressed in the C. glabrata membrane in response to clotrimazole. Functional characterization of this putative drug:H+ antiporter, and of its homolog CgTpo1-1 (ORF CAGL0G03927g), allowed the identification of these proteins as localized to the plasma membrane and conferring azole drug resistance in this fungal pathogen by actively extruding the drug to the external medium. The cell wall protein CgGas1 was also shown to confer azole drug resistance through cell wall remodeling. Finally, the transcription factor CgPdr1 in the clotrimazole response was observed to control the expression of 20 of the identified proteins, thus highlighting the existence of additional unforeseen targets of this transcription factor, recognized as a major regulator of azole drug resistance in clinical isolates.
  • Motokazu Nakayama, Kouichi Hosoya, Yumi Shimizu-Imanishi, Hiroji Chibana, Takashi Yaguchi
    Biocontrol Science 21(2) 73-80 2016年  査読有り
    The number of spoilage incidents in the food industry attributable to a species of the genus Moniliella has recently increased, but the risk of food spoilage has not yet been evaluated. The purpose of this study was to develop a method to rapidly identify high-risk species and to conduct a risk analysis study of Moniliella spp. Acetic acid resistance of M. acetoabutens and ethanol resistance of M. suaveolens were higher than for other Moniliella species. All examined strains of M. acetoabutens developed a high tolerance to acetic acid by being cultured twice in liquid media containing low concentrations of acetic acid. These findings indicate that M. acetoabutens and M. suaveolens are high-risk species for food spoilage and must be discriminated from other fungi. We developed species-specific primers to identify M. acetoabutens and M. suaveolens using the polymerase chain reaction (PCR) to amplify the D1/D2 domain of 28S rDNA. The PCR using the primer sets designed for M. acetoabutens (Mac-F1/R1) and M. suaveolens (Msu-F1/R1) was specific to the target species and did not detect other fungi involved in food spoilage or environmental contamination. This method is expected to be effective for the monitoring of raw materials and components of the food production process.
  • Pedro Pais, Carla Pires, Catarina Costa, Michiyo Okamoto, Hiroji Chibana, Miguel C. Teixeira
    Frontiers in Microbiology 7(DEC) 2045-2045 2016年  査読有り
    © 2016 Pais, Pires, Costa, Okamoto, Chibana and Teixeira. Resistance to 5-flucytosine (5-FC), used as an antifungal drug in combination therapy, compromises its therapeutic action. In this work, the response of the human pathogen Candida glabrata to 5-FC was evaluated at the membrane proteome level, using an iTRAQ-based approach. A total of 32 proteins were found to display significant expression changes in the membrane fraction of cells upon exposure to 5-FC, 50% of which under the control of CgPdr1, the major regulator of azole drug resistance. These proteins cluster into functional groups associated to cell wall assembly, lipid metabolism, amino acid/nucleotide metabolism, ribosome components and translation machinery, mitochondrial function, glucose metabolism, and multidrug resistance transport. Given the obtained indications, the function of the drug:H+ antiporters CgFlr1 (ORF CAGL0H06017g) and CgFlr2 (ORF CAGL0H06039g) was evaluated. The expression of both proteins, localized to the plasma membrane, was found to confer flucytosine resistance. CgFlr2 further confers azole drug resistance. The deletion of CgFLR1 or CgFLR2 was seen to increase the intracellular accumulation of 5-FC, or 5-FC and clotrimazole, suggesting that these transporters play direct roles in drug extrusion. The expression of CgFLR1 and CgFLR2 was found to be controlled by the transcription factors CgPdr1 and CgYap1, major regulator of oxidative stress resistance.
  • Masashi Yamaguchi, Toshihiro Aoyama, Norihiro Yamada, Setsuo Maruta, Hiroji Chibana
    Microscopy 65(5) i25-450 2016年  査読有り
    © 2016, Oxford University Press. All rights reserved. Hydrophilicity/hydrophobicity of the surfaces of plasma-polymerized naphthalene film (Super Support Film, Nisshin EM Co. Ltd., Tokyo), carbon and formvar support films, and copper and nickel grids were quantitatively estimated by contact angles measured from diameters and heights of water droplets placed on various specimens. With treatment of glow discharge, the surfaces of plasma-polymerized naphthalene and carbon support films became fully hydrophilic in 20 seconds. They remained hydrophilic for 6 hours. The surfaces of copper and nickel grids became fully hydrophilic with 60 seconds of glow discharge treatment. They remained hydrophilic for only 1 hour. This information is useful for negative staining, ultrathin sectioning and rapid freezing of biological specimens using the sandwich method [1].
  • Catarina Costa, Andreia Ponte, Pedro Pais, Rui Santos, Mafalda Cavalheiro, Takashi Yaguchi, Hiroji Chibana, Miguel Cacho Teixeira
    PLoS ONE 10(8) e0135110 2015年8月12日  査読有り
    © 2015 Costa et al. 5-Flucytosine is currently used as an antifungal drug in combination therapy, but fungal pathogens are rapidly able to develop resistance against this drug, compromising its therapeutic action. The understanding of the underlying resistance mechanisms is crucial to deal with this problem. In this work, the S. cerevisiae deletion mutant collection was screened for increased resistance to flucytosine. Through this chemogenomics analysis, 183 genes were found to confer resistance to this antifungal agent. Consistent with its known effect in DNA, RNA and protein synthesis, the most significant Gene Ontology terms over-represented in the list of 5-flucytosine resistance determinants are related to DNA repair, RNA and protein metabolism. Additional functional classes include carbohydrate and nitrogen - particularly arginine - metabolism, lipid metabolism and cell wall remodeling. Based on the results obtained for S. cerevisiae as a model system, further studies were conducted in the pathogenic yeast Candida glabrata. Arginine supplementation was found to relieve the inhibitory effect exerted by 5-flucytosine in C. glabrata. Lyticase susceptibility was found to increase within the first 30min of 5-flucytosine exposure, suggesting this antifungal drug to act as a cell wall damaging agent. Upon exponential growth resumption in the presence of 5-flucytosine, the cell wall exhibited higher resistance to lyticase, suggesting that cell wall remodeling occurs in response to 5-flucytosine. Additionally, the aquaglyceroporin encoding genes CgFPS1 and CgFPS2, from C. glabrata, were identified as determinants of 5-flucytosine resistance. CgFPS1 and CgFPS2 were found to mediate 5-flucytosine resistance, by decreasing 5-flucytosine accumulation in C. glabrata cells.
  • Stepanova AA, Vasilyeva NV, Yamaguchi M, Chibana H, Bosak IA
    Problems in Medical Mycology 17 45-50 2015年  招待有り
  • Kunio Nakatsukasa, Takashi Nishimura, Stuart D. Byrne, Michiyo Okamoto, Azusa Takahashi-Nakaguchi, Hiroji Chibana, Fumihiko Okumura, Takumi Kamura
    Molecular Cell 59(1) 22-34 2015年  査読有り
    © 2015 Elsevier Inc. Despite the crucial role played by the glyoxylate cycle in the virulence of pathogens, seed germination in plants, and sexual development in fungi, we still have much to learn about its regulation. Here, we show that a previously uncharacterized SCFUcc1 ubiquitin ligase mediates proteasomal degradation of citrate synthase in the glyoxylate cycle to maintain metabolic homeostasis in glucose-grown cells. Conversely, transcription of the F box subunit Ucc1 is downregulated in C2-compound-grown cells, which require increased metabolic flux for gluconeogenesis. Moreover, invitro analysis demonstrates that oxaloacetate regenerated through the glyoxylate cycle induces a conformational change in citrate synthase and inhibits its recognition and ubiquitination by SCFUcc1, suggesting the existence of an oxaloacetate-dependent positive feedback loop that stabilizes citrate synthase. We propose that SCFUcc1-mediated regulation of citrate synthase acts as a metabolic switch for the glyoxylate cycle in response to changes in carbon source, thereby ensuring metabolic versatility and flexibility.
  • Sayaka Yamaguchi, Ayako Sano, Midori Hiruma, Michiko Murata, Takashi Kaneshima, Yoshiteru Murata, Hideo Takahashi, Sana Takahashi, Yoko Takahashi, Hiroji Chibana, Hidemi Touyama, Nguyen Thi Thanh Ha, Yasutomo Nakazato, You Uehara, Morihiko Hirakawa, Yoshimi Imura, Yoshie Terashima, Yasuhiro Kawamoto, Keji Takahashi, Kazutoshi Sugiyama, Masataro Hiruma, Masaru Murakami, Atsushi Hosokawa, Hiroshi Uezato
    Mycopathologia 178(1-2) 135-143 2014年8月  査読有り
    We investigated 793 bird combs [645 chickens and 148 fighting cocks (Shamo)] to determine the prevalence of dermatophytes and their related fungal species. The targeted fungal species were recovered from 195 of the 793 examined birds (24.6 %). Prevalence ratios were compared in temperate (the mainland) and subtropical (Nansei Islands) areas, genders, strains, breeding scale (individual and farm), and housing system (in cage and free ranging). The frequency of the fungal species in the mainland, males, fighting cocks, breeding scale by individual nursing, and free-range housing system exhibited significantly higher positive ratios than that in the other groups. A total of 224 dermatophytes and related species were isolated, including 101 Arthroderma (Ar.) multifidum, 83 Aphanoascus (Ap.) terreus, five Uncinocarpus queenslandicus, two U. reesii, two Ap. pinarensis, one Amauroascus kuehnii, one Ar. simii, one Gymnoascus petalosporus, one Microsporum gallinae, and 28 Chrysosporium-like (Chrysosporium spp.) isolates, which were identified using internal transcribed spacer regions of ribosomal RNA gene sequences. The predominant fungal species in the mainland was Ap. terreus and that in the Nansei Islands was Ar. multifidum. Pathogenic fungal species to humans and animals were limited to M. gallinae and Ar. simii, which corresponded to 0.025 % of the isolates in this study. © 2014 Springer Science+Business Media Dordrecht.
  • Kiminori Shimizu, Yumi Imanishi, Akio Toh-e, Jun Uno, Hiroji Chibana, Christina M. Hull, Susumu Kawamoto
    Fungal Genetics and Biology 69 13-22 2014年8月  査読有り
    Diazobenzoic acid B (DBB), also known as diazonium blue B or fast blue B, can be used to distinguish basidiomycetous yeasts from ascomycetes. This chemical has long been used for the taxonomic study of yeast species at the phylum level, but the mechanism underlying the DBB staining remains unknown. To identify molecular targets of DBB staining, we isolated Agrobacterium tumefaciens-mediated insertional mutants of Cryptococcus neoformans, a basidiomycetous pathogenic yeast, which were negative to DBB staining. In one of these mutants, we found that the PMT2 gene, encoding a protein- O-mannosyltransferase, was interrupted by a T-DNA insertion. A complete gene knockout of the PMT2 gene revealed that the gene was responsible for DBB staining in C. neoformans, suggesting that one of the targets of Pmt2-mediated glycosylation is responsible for interacting with DBB. We also determined that Cryptococcus gattii, a close relative of C. neoformans, was not stained by DBB when the PMT2 gene was deleted. Our finding suggests that the protein- O-mannosylation by the PMT2 gene product is required for DBB staining in Cryptococcus species in general. We also showed that glycosylation in Cryptococcus by Pmt2 plays important roles in controlling cell size, resistance to high temperature and osmolarity, capsule formation, sexual reproduction, and virulence. © 2014 Elsevier Inc.
  • Catarina Costa, Joana Nunes, André Henriques, Nuno P. Mira, Hironobu Nakayama, Hiroji Chibana, Miguel C. Teixeira
    Journal of Antimicrobial Chemotherapy 69(7) 1767-1776 2014年7月  査読有り
    Objectives: The ability of opportunistic pathogenic Candida species to persist and invade specific niches in the human host depends on their resistance to natural growth inhibitors and antifungal therapy. This work describes the role of the Candida glabrata drug:H+ antiporter CgTpo3 (ORF CAGL0I10384g) in this context. Methods: Deletion and cloning of CgTPO3 was achieved using molecular biology tools. C. glabrata strain susceptibility was assayed based on growth in liquid and solid media and through MIC determination. Radiolabelled compound accumulation or HPLC were used for the assessment of the role of CgTpo3 as a drug or polyamine transporter. Quantitative RT-PCR was used for expression analysis. Results: CgTpo3 was found to confer resistance to azole drugs in C. glabrata. This protein was found to be localized to the plasma membrane and to decrease the intracellular accumulation of [3H]clotrimazole, playing a direct role in its extrusion from pre-loaded C. glabrata cells. CgTPO3 was further found to confer resistance to spermine, complementing the susceptibility phenotypes exhibited by the deletion of its Saccharomyces cerevisiae homologue, TPO3. In spermine-stressed C. glabrata cells, CgTPO3 is transcriptionally activated in a CgPdr1-dependent manner, contributing to a decrease in the intracellular concentration of this polyamine. Clotrimazole exposure was found to lead to the intracellular accumulation of spermine, and pre-exposure to this polyamine was found consistently to lead to increased clotrimazole resistance. Conclusions: Altogether, these results point to a significant role for CgTpo3 in azole drug resistance and in the tolerance to high polyamine concentrations, such as those found in the urogenital tract. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
  • Toshihiro Aoyama, Hironobu Nakayama, Keigo Ueno, Tatsuya Inukai, Koichi Tanabe, Minoru Nagi, Martin Bard, Hiroji Chibana
    Genes to Cells 19(6) 478-503 2014年6月  査読有り
    DNA sequencing of the 5′-flanking region of the transcriptome effectively identifies transcription initiation sites and also aids in identifying unknown genes. This study describes a comprehensive polling of transcription start sites and an analysis of full-length complementary DNAs derived from the genome of the pathogenic fungus Candida glabrata. A comparison of the sequence reads derived from a cDNA library prepared from cells grown under different culture conditions against the reference genomic sequence of the Candida Genome Database (CGD: http://www.candidagenome.org/) revealed the expression of 4316 genes and their acknowledged transcription start sites (TSSs). In addition this analysis also predicted 59 new genes including 22 that showed no homology to the genome of Saccharomyces cerevisiae, a genetically close relative of C. glabrata. Furthermore, comparison of the 5′-untranslated regions (5′-UTRs) and core promoters of C. glabrata to those of S. cerevisiae showed various global similarities and differences among orthologous genes. Thus, the C. glabrata transcriptome can complement the annotation of the genome database and should provide new insights into the organization, regulation, and function of genes of this important human pathogen. © 2014 by the Molecular Biology Society of Japan and Wiley Publishing Asia Pty Ltd.
  • Catarina Costa, Carla Pires, Tânia R. Cabrito, Adeline Renaudin, Michiyo Ohno, Hiroji Chibana, Isabel Sá-Correia, Miguel C. Teixeira
    Antimicrobial Agents and Chemotherapy 57(7) 3159-3167 2013年7月  査読有り
    The widespread emergence of antifungal drug resistance poses a severe clinical problem. Though predicted to play a role in this phenomenon, the drug:H+ antiporters (DHA) of the major facilitator superfamily have largely escaped characterization in pathogenic yeasts. This work describes the first DHA from the pathogenic yeast Candida glabrata reported to be involved in antifungal drug resistance, the C. glabrata QDR2 (CgQDR2) gene (ORF CAGL0G08624g). The expression of CgQDR2 in C. glabrata was found to confer resistance to the antifungal drugs miconazole, tioconazole, clotrimazole, and ketoconazole. By use of a green fluorescent protein (GFP) fusion, the CgQdr2 protein was found to be targeted to the plasma membrane in C. glabrata. In agreement with these observations, CgQDR2 expression was found to decrease the intracellular accumulation of radiolabeled clotrimazole in C. glabrata and to play a role in the extrusion of this antifungal from preloaded cells. Interestingly, the functional heterologous expression of CgQDR2 in the model yeast Saccharomyces cerevisiae further confirmed the role of this gene as a multidrug resistance determinant: its expression was able to complement the susceptibility phenotype exhibited by its S. cerevisiae homologue, QDR2, in the presence of imidazoles and of the antimalarial and antiarrhythmic drug quinidine. In contrast to the findings reported for Qdr2, CgQdr2 expression does not contribute to the ability of yeast to grow under K+-limiting conditions. Interestingly, CgQDR2 transcript levels were seen to be upregulated in C. glabrata cells challenged with clotrimazole or quinidine. This upregulation was found to depend directly on the transcription factor CgPdr1, the major regulator of multidrug resistance in this pathogenic yeast, which has also been found to be a determinant of quinidine and clotrimazole resistance in C. glabrata. Copyright © 2013, American Society for Microbiology.
  • Minoru Nagi, Koichi Tanabe, Keigo Ueno, Hironobu Nakayama, Toshihiro Aoyama, Hiroji Chibana, Satoshi Yamagoe, Takashi Umeyama, Takahiro Oura, Hideaki Ohno, Susumu Kajiwara, Yoshitsugu Miyazaki
    Molecular Microbiology 88(2) 371-381 2013年4月  査読有り
    Summary: During disseminated infection by the opportunistic pathogen Candida glabrata, uptake of sterols such as serum cholesterol may play a significant role during pathogenesis. The ATP-binding cassette transporter Aus1p is thought to function as a sterol importer and in this study, we show that uptake of exogenous sterols occurred under anaerobic conditions in wild-type cells of C.glabrata but not in AUS1-deleted mutant (aus1Δ) cells. In aerobic cultures, growth inhibition by fluconazole was prevented in the presence of serum, and AUS1 expression was upregulated. Uptake of sterol by azole treated cells required the presence of serum, and sterol alone did not reverse FLC inhibition of growth. However, if iron availability in the growth medium was limited by addition of the iron chelators ferrozine or apo-transferrin, growth of wild-type cells, but not aus1Δ cells, was rescued. In a mouse model of disseminated infection, the C.glabrataaus1Δ strain caused a significantly decreased kidney fungal burden than the wild-type strain or a strain in which AUS1 was restored. We conclude that sterol uptake in C.glabrata can occur in iron poor environment of host tissues and thus may contribute to C.glabrata pathogenesis. © 2013 Blackwell Publishing Ltd.
  • Michiko Murata, Hideo Takahashi, Sana Takahashi, Yoko Takahashi, Hiroji Chibana, Yoshiteru Murata, Kazutoshi Sugiyama, Takashi Kaneshima, Sayaka Yamaguchi, Hitona Miyasato, Masaru Murakami, Rui Kano, Atsuhiko Hasegawa, Hiroshi Uezato, Atsushi Hosokawa, Ayako Sano
    Medical Mycology 51(2) 144-149 2013年2月  査読有り
    A case of tinea corporis caused by Microsporum gallinae was found in 2011 in Okinawa, located in the southern part of Japan. The patient was a 96-year-old, otherwise healthy, Japanese man, who had been working as a breeder of fighting cocks for more than 70 years. He was bitten on his right forearm by one of the cocks and a few weeks later, two erythematous macules appeared on the right forearm, accompanied by a slight itchy sensation. While the first isolate of this dermatophyte was recovered from the region by Miyasato et al. in 2011, it was not obtained from the same fighting cock owned by the patient. However, frequent exchanges of fighting cocks and special domestic breeds of chickens related to fighting, mating, and/or bird fairs are common among the fans and breeders. We investigated 238 chickens and 71 fighting cocks in Okinawa and in the suburbs of Tokyo (Chiba, Tokyo, Ibaraki, and Sizuoka). One isolate of M. gallinae from a fighting cock in Chiba Prefecture in the Tokyo metropolitan area exhibited a different genotype, with a single base difference from the patient isolate based on the internal transcribed spacer 1-5.8s-ITS2 regions (ITS1-5.8S-ITS2) of the ribosomal RNA gene sequence. The isolation of M. gallinae from a fighting cock on the mainland of Japan is the first such finding in animals in our country. © 2013 ISHAM.
  • Keiichi Ueda, Ayako Sano, Jyoji Yamate, Eiko Itano Nakagawa, Mitsuru Kuwamura, Takeshi Izawa, Miyuu Tanaka, Yuko Hasegawa, Hiroji Chibana, Yasuharu Izumisawa, Hirokazu Miyahara, Senzo Uchida
    Case Reports in Veterinary Medicine 2013 2013年  査読有り
    © 2013 Hindawi Limited. All rights reserved. Lacaziosis, formerly called lobomycosis, caused by Lacazia loboi, is a zoonotic mycosis found in humans and dolphins and is endemic in the countries on the Atlantic Ocean. Although the Japanese coast is not considered an endemic area, photographic records of lacaziosis-like skin lesions were found in bottlenose dolphins (Tursiops truncatus) that were migrating in theGoto Islands (Nagasaki Prefecture, Japan).We diagnosed 2 cases of lacaziosis in bottlenose dolphins captured simultaneously at the same coast within Japanese territory on the basis of clinical characteristics, cytology, histopathology, immunological tests, and detection of partial sequences of a 43 kDa glycoprotein coding gene (gp43) with a nested-PCR system.The granulomatous skin lesions fromthe present cases were similar to those found in animals from endemic areas, containing multiple budding and chains of round yeast cells and positive in the immune-staining with anti-Paracoccidioides brasiliensis serum which is a fungal species related to L. Loboi; however, the gp43 gene sequences derived from the present cases showed 94.1% homology to P. Brasiliensis and 84.1% to L. Loboi. We confirmed that the causative agent at the present cases was different genotype of L. Loboi from Amazon area.
  • Catarina Costa, André Henriques, Carla Pires, Joana Nunes, Michiyo Ohno, Hiroji Chibana, Isabel Sá-Correia, Miguel C. Teixeira
    Frontiers in Microbiology 4(JUN) 170-170 2013年  査読有り
    Opportunistic Candida species often have to cope with inhibitory concentrations of acetic acid, in the acidic environment of the vaginal mucosa. Given that the ability of these yeast species to tolerate stress induced by weak acids and antifungal drugs appears to be a key factor in their persistence and virulence, it is crucial to understand the underlying mechanisms. In this study, the drug:H+ antiporter CgAqr1 (ORF CAGL0J09944g), from Candida glabrata, was identified as a determinant of resistance to acetic acid, and also to the antifungal agents flucytosine and, less significantly, clotrimazole. These antifungals were found to act synergistically with acetic acid against this pathogen. The action of CgAqr1 in this phenomenon was analyzed. Using a green fluorescent protein fusion, CgAqr1 was found to localize to the plasma membrane and to membrane vesicles when expressed in C. glabrata or,heterologously, in Saccharomyces cerevisiae. Given its ability to complement the susceptibility phenotype of its S. cerevisiae homolog, ScAqr1, CgAqr1 was proposed to play a similar role in mediating the extrusion of chemical compounds. Significantly, the expression of this gene was found to reduce theintracellular accumulation of 3H-flucytosine and, to a moderate extent, of 3H-clotrimazole, consistent with a direct role in antifungal drug efflux. Interestingly, no effect of CgAQR1 deletion could be found on the intracellular accumulation of 14C-acetic acid, suggesting that its role in acetic acid resistance may be indirect, presumably through the transport of a still unidentified physiological substrate. Although neither of the tested chemicals induces changes in CgAQR1 expression, pre-exposure to flucytosine or clotrimazole was found to make C. glabrata cells more sensitive to acetic acid stress. Results from this study show that CgAqr1 is an antifungal drug resistance determinant and raise the hypothesis that it may play a role in C. glabrata persistent colonization and multidrug resistance. © 2013 Costa, Henriques, Pires, Nunes, Ohno, Chibana, Sá-Correia and Teixeira.
  • Junichi I. Nagao, Tamaki Cho, Jun Uno, Keigo Ueno, Rieko Imayoshi, Hironobu Nakayama, Hiroji Chibana, Hidenori Kaminishi
    FEMS Yeast Research 12(6) 728-737 2012年9月  査読有り
    We investigated the cellular function of Msi3p, belonging to the heat shock protein 70 family, in Candida albicans. The mutant strain tetMSI3 was generated, in which MSI3 was controlled by a tetracycline-repressive promoter, because there is evidence to suggest that MSI3 is an essential gene. We controlled the MSI3 expression level by doxycycline (DOX) and compared its phenotype with that of a control strain with the tetracycline-repressive promoter and a wild-type copy MSI3. The results indicated that MSI3 was essential for cell growth. In addition, all the tetMSI3-infected mice survived after DOX administration. Drug susceptibility tests indicated that repression of MSI3 expression resulted in hypersensitivity to fluconazole and conferred fungicidal activity to fluconazole. The expression levels of MSI3 and calcineurin-dependent genes were upregulated in response to fluconazole in the control strain. In tetMSI3, the upregulation of MSI3 was lost, and the expression level of the calcineurin-dependent genes was no longer elevated in response to fluconazole and was not affected by DOX, indicating that the upregulation of MSI3 expression was required for the induction of the calcineurin-dependent gene expression. These data suggest that Msi3p confers fluconazole tolerance by partially influencing the calcineurin signaling pathway and also other tolerance mechanisms. © 2012 Federation of European Microbiological Societies.
  • Kyoko Niimi, Matthew A. Woods, Katsuyuki Maki, Hironobu Nakayama, Kazuaki Hatakenaka, Hiroji Chibana, Fumiaki Ikeda, Keigo Ueno, Masakazu Niimi, Richard D. Cannon, Brian C. Monk
    Journal of Antimicrobial Chemotherapy 67(7) 1666-1676 2012年7月  査読有り
    Objectives: A mechanism for the acquisition of high-level echinocandin resistance in Candida glabrata was investigated. FKS mutants were constructed to: determine whether clinically significant micafungin resistance requires a hot-spot mutation in FKS1 and a premature stop codon in FKS2, as was observed in a clinical isolate; select for variants with reduced susceptibility and locate mutations in FKS genes; and assess the roles of FKS1 and FKS2. Methods: A panel of FKS mutants was constructed using micafungin-susceptible parents by site-directed mutagenesis. Drug susceptibility, gene expression and glucan synthase activities were compared between mutants. Mutations acquired by selection were identified by DNA sequence analysis of FKS genes from selected variants. Single FKS deletants were constructed and their phenotypes examined. Results: Introduction of the hot-spot mutation in FKS1 alone conferred an intermediate reduction in susceptibility, and the premature stop codon in FKS2 alone had no effect on susceptibility, while severely reduced susceptibility equivalent to that of the clinical isolate required both mutations. Exposure of susceptible strains to micafungin yielded variants with an intermediate reduction in susceptibility that possessed a hot-spot mutation in FKS1. Further exposure to micafungin yielded variants with severely reduced susceptibility that acquired various single mutations in FKS2. The phenotypes of δfks1 and δfks2 mutants indicate that the two FKS genes are functionally redundant, while deletion of both FKS1 and FKS2 conferred synthetic lethality. Conclusions: In the laboratory mutants of C. glabrata, clinically significant reduced susceptibility to micafungin required single nucleotide changes in both FKS1 and FKS2, and both genes encoded β-1,3-glucan synthase catalytic subunits. © The Author 2012. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
  • Keigo Ueno, Yasuhiko Matsumoto, Jun Uno, Kaname Sasamoto, Kazuhisa Sekimizu, Yuki Kinjo, Hiroji Chibana
    PLoS ONE 6(9) e24759 2011年9月9日  査読有り
    The intestinal resident Candida glabrata opportunistically infects humans. However few genetic factors for adaptation in the intestine are identified in this fungus. Here we describe the C. glabrata CYB2 gene encoding lactate dehydrogenase as an adaptation factor for survival in the intestine. CYB2 was identified as a virulence factor by a silkworm infection study. To determine the function of CYB2, we analysed in vitro phenotypes of the mutant Δcyb2. The Δcyb2 mutant grew well in glucose medium under aerobic and anaerobic conditions, was not supersensitive to nitric oxide which has fungicidal-effect in phagocytes, and had normal levels of general virulence factors protease, lipase and adherence activities. A previous report suggested that Cyb2p is responsible for lactate assimilation. Additionally, it was speculated that lactate assimilation was required for Candida virulence because Candida must synthesize glucose via gluconeogenesis under glucose-limited conditions such as in the host. Indeed, the Δcyb2 mutant could not grow on lactate medium in which lactate is the sole carbon source in the absence of glucose, indicating that Cyb2p plays a role in lactate assimilation. We hypothesized that Cyb2p-mediated lactate assimilation is necessary for proliferation in the intestinal tract, as the intestine is rich in lactate produced by bacteria flora, but not glucose. The Δcyb2 mutant showed 100-fold decreased adaptation and few cells of Saccharomyces cerevisiae can adapt in mouse ceca. Interestingly, C. glabrata could assimilate lactate under hypoxic conditions, dependent on CYB2, but not yeast S. cerevisiae. Because accessible oxygen is limited in the intestine, the ability for lactate assimilation in hypoxic conditions may provide an advantage for a pathogenic yeast. From those results, we conclude that Cyb2p-mediated lactate assimilation is an intestinal adaptation factor of C. glabrata. © 2011 Ueno et al.
  • Keigo Ueno, Yuichi Namiki, Hiroki Mitani, Masashi Yamaguchi, Hiroji Chibana
    FEMS Yeast Research 11(5) 398-407 2011年8月  査読有り
    It is known that cell wall remodeling and the salvaging pathway act to compensate for an impaired or a damaged cell wall. Lately, it has been indicated that this mechanism is partly required for resistance to the glucan synthesis inhibitor echinocandin. While cell wall remodeling has been described in mutants of glucan or mannan synthesis, it has not yet been reported in a chitin synthesis mutant. Here, we describe a novel cell wall remodeling and salvaging pathway in chitin synthesis mutants, Δchs3A and Δchs3B, of the pathogenic yeast Candida glabrata. Electron microscopic analysis revealed a thickened mannoprotein layer in Δchs3A cells and a thickened chitin-glucan layer of Δchs3B cells, and it indicated the hypothesis that mannan synthase and chitin-glucan synthase indemnify Δchs3A and Δchs3B cells, respectively. The double-mutant CHS3A and MNN10, encoding α-1,6-mannosyltransferase, showed synergistic stress sensitization, and the Δchs3B strain showed supersensitivity to echinocandins. Hence, these findings support the above hypothesis of remodeling. Furthermore, unlike Δchs3A cells, Δchs3B cells showed supersensitivity to calcineurin inhibitor FK506 and Tor1p kinase inhibitor rapamycin, indicating that the Δchs3B strain uses the calcineurin pathway and a Tor1p kinase for cell wall remodeling. © 2011 Federation of European Microbiological Societies.
  • Hironobu Nakayama, Keigo Ueno, Jun Uno, Minoru Nagi, Koichi Tanabe, Toshihiro Aoyama, Hiroji Chibana, Martin Bard
    FEMS Microbiology Letters 317(1) 27-33 2011年4月  査読有り
    Farnesyl pyrophosphate (FPP) is utilized for many cellular processes, including the production of dolichols, ubiquinone (CoQ), sterols, farnesylated heme A and prenylated proteins. This lipid synthesized by FPP synthetase (ERG20) becomes attached to target proteins by the prenyltransferases, CDC43/RAM2 and RAM1/RAM2 complexes after the formation of the C15 and C20 units, respectively. Defects in protein prenylation as a result of inhibiting these enzyme complexes lead to pleiotropic effects in all eukaryotes. In this study, using Candida glabrata conditional mutants, the importance of the ERG20 and RAM2 genes for growth using both in vivo and in vitro assays was assessed by placing the RAM2 and ERG20 genes under the control of a regulatable promoter. Repression of RAM2 gene expression revealed growth defects under both conditions. However, repression of ERG20 gene expression did not impair fungal growth in a mouse host, but did result in growth defects on laboratory media. Thus, FPP synthase is not required for survival in an infected mouse, but the RAM2-encoded prenyltransferase was critical for growth under both conditions. This study strongly suggests that inhibitors of prenyltransferase may be promising antifungals. © 2011 Federation of European Microbiological Societies.
  • Yuichi Namiki, Keigo Ueno, Hiroki Mitani, Eric V. Virtudazo, Misako Ohkusu, Kiminori Shimizu, Susumu Kawamoto, Hiroji Chibana, Masashi Yamaguchi
    Journal of Electron Microscopy 60(2) 157-165 2011年4月  査読有り
    Protoplast regeneration of a wild-type and two mutant strains of Candida glabrata defective in CHS3 homologues encoding class IV chitin synthase in Saccharomyces cerevisiae was examined by scanning and negative-staining electron microscopy. In the wild-type strain, small particles and short filaments appeared on the protoplast surface at 10 min, filamentous materials covered the entire surface of the protoplast at 1 h, granular materials started filling interspaces of filamentous materials at 2 h and regeneration was completed at 6 h. The filamentous materials consisted of microfibrils of various widths ranging from ≤5 to 40 nm, and composed of -glucan. Protoplasts of the two chitin synthase mutant strains of chs3A and chs3B completed regeneration essentially by the same process as wild-type strain, although it took more time. These results suggest that CHS3A and CHS3B genes may have important roles in cell wall formation during protoplast regeneration, but can be compensated by other cell wall enzymes. © 2011 The Author Published by Oxford University Press [on behalf of Japanese Society of Microscopy]. All rights reserved.
  • Minoru Nagi, Hironobu Nakayama, Koichi Tanabe, Martin Bard, Toshihiro Aoyama, Makoto Okano, Satoru Higashi, Keigo Ueno, Hiroji Chibana, Masakazu Niimi, Satoshi Yamagoe, Takashi Umeyama, Susumu Kajiwara, Hideaki Ohno, Yoshitsugu Miyazaki
    Genes to Cells 16(1) 80-89 2011年1月  査読有り
    Zn[2]-Cys[6] binuclear transcription factors Upc2p and Ecm22p regulate the expression of genes involved in ergosterol biosynthesis and exogenous sterol uptake in Saccharomyces cerevisiae. We identified two UPC2/ECM22 homologues in the pathogenic fungus Candida glabrata which we designated CgUPC2A and CgUPC2B. The contribution of these two genes to sterol homeostasis was investigated. Cells that lack CgUPC2A (upc2Aδ) exhibited enhanced susceptibility to the sterol biosynthesis inhibitors, fluconazole and lovastatin, whereas upc2Bδ-mutant cells were as susceptible to the drugs as wild-type cells. The growth of upc2Aδ cells was also severely attenuated under anaerobic conditions. Lovastatin treatment enhanced the expression of ergosterol biosynthetic genes, ERG2 and ERG3 in wild-type and upc2Bδ but not in upc2Aδ cells. Similarly, serum-induced expression of ERG2 and ERG3 was completely impaired in upc2Aδ cells but was unaffected in upc2Bδ cells, whereas serum-induced expression of the sterol transporter gene CgAUS1 was impaired in both upc2Aδ and upc2Bδ cells. These results suggest that in C. glabrata CgUPC2A but not in CgUPC2B is the main transcriptional regulator of the genes responsible for maintaining sterol homeostasis as well as susceptibility to sterol inhibitors. © 2010 The Authors. Journal compilation © 2010 by the Molecular Biology Society of Japan/Blackwell Publishing Ltd.
  • Keigo Ueno, Yutaka Tamura, Hiroji Chibana
    Yeast 27(7) 369-378 2010年7月  査読有り
    The emergence of antifungal drug resistance is triggering vigorous searches for novel antifungal targets and lead compounds. In this study, we focused on fungal profilin, which is a small actin control protein sharing limited homology to human profilin. To validate its potentiality as a target, a profilin-conditional mutant of the pathogenic yeast Candida glabrata was constructed, using a regulatable Tet promoter, and its growth was monitored in vitro. Repression of profilin expression led to severe growth defect, demonstrating the potential of this protein as a novel antifungal target. Next, novel peptides binding to the active interface of profilin were designed by computer simulation. ELISA analysis showed that these peptides did bind to the wild-type profilin but bound less strongly to a profilin with amino acid substitutions at the active interface. Hence, we show here that profilin is a potential antifungal target and offer novel peptide ligands. Copyright © 2010 John Wiley & Sons, Ltd.
  • Juhaer Mijiti, Xiong Ming Pu, Alshat Erfan, Takashi Yaguchi, Hiroji Chibana, Reiko Tanaka
    Japanese Journal of Medical Mycology 51(3) 165-168 2010年  査読有り
    Antifungal susceptibility tests were performed for 38 Candida albicans strains isolated from oral cavities of 43 Uighurian AIDS patients. Results showed that six isolates were resistant to fluconazole; one showed low susceptibility. We attempted to examine these strains molecular-epidemiologically, but 25S rDNA genotyping was insufficient for their discrimination. To estimate whether the origins of resistant strains were identical, we developed a new combination method of C. albicans tandem repeating units (ALTS)/RFLP and micro-temperature gradient gel electrophoresis (μ-TGGE). This new method was able to distinguish all seven strains. A suspected nosocomial infection was ruled out.
  • Hisao Hattori, Reiko Tanaka, Hiroji Chibana, Fumihiko Kawamoto, Hidesada Adachi, Kazue Shimizu, Toshio Kanbe
    Japanese Journal of Infectious Diseases 62(3) 215-219 2009年  査読有り
    The nucleotide sequences of the inner repeats of the repetitive sequence (RPS), termed ALTs, of Candida albicans and its related species C. albicans var. stellatoidea and C. dubliniensis, were analyzed. ALT sequences were grouped into 4 types for C. albicans (Aa, Ab, Ac and Ad) and C. albicans var. stellatoidea (Sa1, Sa2, Sb, Sc and Sd), and 3 types for C. dubliniensis (Da, Db and Dc). In addition to the primer set P-II (specific to RPS), 2 primer sets (AS-I and AiR-I) specific to the nucleotide sequences of C. albicans ALT were designed and tested for their potential for RPS-based identification/genotyping of C. albicans. PCRs using AS-I and AiR-I clearly distinguished C. albicans from both C. albicans var. stellatoidea and C. dubliniensis. Furthermore, the strains of C. albicans that showed similar electrophoretic patterns in the PCR using P-II were discriminated at the subtype level. These results indicate that the PCRs using RPS- and ALT-specific primer sets are useful as simple and rapid systems for the specific identification and genotyping of C. albicans.
  • Hiroji Chibana, Paul T. Magee
    Future Microbiology 4(2) 171-179 2009年  査読有り
    The major repeat sequence, discovered in the yeast Candida albicans, is a stretch of repeated DNA that occurs nine times in the haploid genome of this opportunistic fungal pathogen and probably a similar number of times in the genome of Candida dubliniensis. In C. albicans it constitutes 1-2% of the genome. Its occurrence is limited to those two species. Despite its major role as a genomic feature, its function, mode of expansion in size due to duplication of internal subunits, and its origin and mechanism of distribution throughout the genome are not understood, although it is associated with chromosome translocations, chromosome length polymorphisms and regulation of the yeast-hypha dimorphic transition. The polymorphism of the major repeat sequence has been exploited in epidemiology and taxonomic studies. This review describes its sequence, occurrence, use in epidemiology and examines the evidence for its role in chromosome dynamics. © 2009 Future Medicine.
  • Hidesada Adachi, Kazue Shimizu, Hisao Hattori, Reiko Tanaka, Hiroji Chibana, Yuki Takagi, Yasushi Tomita, Toshio Kanbe
    Japanese Journal of Medical Mycology 50(3) 167-174 2009年  査読有り
    Because of its high discriminatory potential, fragment analysis of microsatellites has been frequently used for genotyping of Candida albicans at the strain level. In order to evaluate a genotyping system based on the fragment analysis of microsatellites combined with PCRs targeting 25S rDNA and RPS, 456 independent strains of C. albicans were subjected to genotype analysis using 4 microsatellite markers (CDC3, HIS3, CAI and CAIII), followed by 25S rDNA and RPS-based genotyping. The fragment analysis using CAI showed the highest discriminatory potential (DP=0.9782), followed by HIS3 (DP=0.8780). Using combined microsatellite markers, 456 C. albicans strains were divided into 384 genotypes (DP=0.9984). PCRs targeting 25S rDNA and RPS were performed to differentiate the strains that showed identical genotypes in the fragment analysis, resulting in 434 genotypes (DP=0.9996). The combined genotyping system showed high discriminatory power at the strain level and therefore is useful for rapid genotyping in molecular epidemiological studies of candidiasis.
  • 長環, 青山俊弘, 豊田美香, 中山浩伸, 知花博治, 上西秀則
    日本医真菌誌 49(4) 281-286 2008年  
  • 長環, 青山俊弘, 豊田美香, 中山浩伸, 知花博治, 上西秀則, CALDERONE Richard A
    日本医真菌学会雑誌 49(4) 2008年  
  • 田辺公一, 名木稔, 中山浩伸, 山越智, 臺由紀, 知花博治, 新見昌一, 宮崎義継
    生化学 2008年  
  • Hironobu Nakayama, Koichi Tanabe, Martin Bard, Wesley Hodgson, Sung Wu, Daiki Takemori, Toshihiro Aoyama, Selvamuthu N. Kumaraswami, Laurel Metzler, Yukie Takano, Hiroji Chibana, Masakazu Niimi
    Journal of Antimicrobial Chemotherapy 60(6) 1264-1272 2007年12月  査読有り
    Objectives: The uptake of endogenous sterol from serum may allow Candida glabrata to survive azole treatment. This study aims to determine the contribution of a sterol transporter that alters fluconazole sensitivity in the presence of serum. Methods: Bioinformatic analysis predicted CgAUS1 as the C. glabrata orthologue of the Saccharomyces cerevisiae transporters AUS1 and PDR11. To investigate whether the CgAUS1 gene has sterol transporter activity, we investigated the effects of an AUS1 deletion on the growth of a tetracycline-regulatable ERG9 strain (tet-ERG9aus1), wherein ERG9 expression is turned off giving rise to a sterol requirement. Tetracycline-dependent repression of CgAUS1 in the tet-AUS1 strain was used to determine the fluconazole susceptibility of CgAUS1 in the presence and absence of serum. Results: The tetracycline-treated tet-ERG9aus1 strain failed to grow in the presence of serum, whereas the parental tet-ERG9AUS1 strain grew by incorporating sterol from exogenously supplied serum. Serum cholesterol protected cells against the antifungal effects of fluconazole and this protection was lost by repressing CgAUS1 gene expression. Furthermore, such protection was also observed during itraconazole treatment, but not observed in cells treated with non-azole antifungals. Conclusions: CgAUS1 appears to function as a sterol transporter that may contribute to lower azole susceptibility in the presence of serum and to protect C. glabrata against azole toxicity in vivo. © The Author 2007. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
  • Keigo Ueno, Jun Uno, Hironobu Nakayama, Kaname Sasamoto, Yuzuru Mikami, Hiroji Chibana
    Eukaryotic Cell 6(7) 1239-1247 2007年7月  査読有り
    In the pathogenic yeast Candida glabrata, gene targeting to generate knockouts and "knockins" is a potentially powerful method for the analysis of gene function. Its importance increased after the C. glabrata genome sequence project, but progress in the field is hampered by inefficient mechanisms for gene targeting. With the use of 40-bp homologous flanking DNA, no gene targeting was identified. To address this issue, YKU80 was disrupted, leading to an increase in targeting efficiency of 5.1% using 40-bp flanking homologous DNA. To harness the beneficial effects of YKU80 inactivation on gene targeting frequency without incurring any negative effects, such as synthetic sickness or lethality, we developed a new system whereby the expression of YKU80 was restored following a transient knockdown of expression during transformation. Strains used for this new system carried a SAT1 flipper in the YKU80 promoter region, which was used to repress expression during transformation but was spontaneously excised from the locus after the transformation. By using this strain, DNA damage induced by methyl methane sulfonate, H2O2, UV irradiation, and hydroxyurea before and during gene targeting was evaluated and the mutation rate of URA3 was determined. No significant effects of the SAT1 flipper on these processes have been identified. After the SAT1 flipper is excised, a 34-bp FLP recombination target sequence is left in the promoter region. However, the levels of mRNA transcription were restored and no difference in the survival ratio in vivo compared to that with the YKU80 wild-type strain was identified. Copyright © 2007, American Society for Microbiology. All Rights Reserved.
  • Marco Van het Hoog, Timothy J. Rast, Mikhail Martchenko, Suzanne Grindle, Daniel Dignard, Hervé Hogues, Christine Cuomo, Matthew Berriman, Stewart Scherer, B. B. Magee, Malcolm Whiteway, Hiroji Chibana, André Nantel, P. T. Magee
    Genome Biology 8(4) R52 2007年4月  査読有り
    Background: The 10.9× genomic sequence of Candida albicans, the most important human fungal pathogen, was published in 2004. Assembly 19 consisted of 412 supercontigs, of which 266 were a haploid set, since this fungus is diploid and contains an extensive degree of heterozygosity but lacks a complete sexual cycle. However, sequences of specific chromosomes were not determined. Results: Supercontigs from Assembly 19 (183, representing 98.4% of the sequence) were assigned to individual chromosomes purified by pulse-field gel electrophoresis and hybridized to DNA microarrays. Nine Assembly 19 supercontigs were found to contain markers from two different chromosomes. Assembly 21 contains the sequence of each of the eight chromosomes and was determined using a synteny analysis with preliminary versions of the Candida dubliniensis genome assembly, bioinformatics, a sequence tagged site (STS) map of overlapping fosmid clones, and an optical map. The orientation and order of the contigs on each chromosome, repeat regions too large to be covered by a sequence run, such as the ribosomal DNA cluster and the major repeat sequence, and telomere placement were determined using the STS map. Sequence gaps were closed by PCR and sequencing of the products. The overall assembly was compared to an optical map; this identified some misassembled contigs and gave a size estimate for each chromosome. Conclusion: Assembly 21 reveals an ancient chromosome fusion, a number of small internal duplications followed by inversions, and a subtelomeric arrangement, including a new gene family, the TLO genes. Correlations of position with relatedness of gene families imply a novel method of dispersion. The sequence of the individual chromosomes of C. albicans raises interesting biological questions about gene family creation and dispersion, subtelomere organization, and chromosome evolution. © 2007 van het Hoog et al.; licensee BioMed Central Ltd.
  • 岩田哲郎, 長環, 西川和範, 青山俊弘, 上野圭吾, 知花博治, 中山浩伸
    生化学 2007年  
  • 知花博治
    感染・炎症・免疫 37(4) 78-80 2007年  招待有り
  • Marco van het Hoog, Timothy J Rast, Mikhail Martchenko, Suzanne Grindle, Daniel Dignard, Hervé Hogues, Christine Cuomo, Matthew Berriman, Stewart Scherer, B B Magee, Malcolm Whiteway, Hiroji Chibana, André Nantel, P T Magee
    Genome biology 8(4) R52 2007年  査読有り
    BACKGROUND: The 10.9x genomic sequence of Candida albicans, the most important human fungal pathogen, was published in 2004. Assembly 19 consisted of 412 supercontigs, of which 266 were a haploid set, since this fungus is diploid and contains an extensive degree of heterozygosity but lacks a complete sexual cycle. However, sequences of specific chromosomes were not determined. RESULTS: Supercontigs from Assembly 19 (183, representing 98.4% of the sequence) were assigned to individual chromosomes purified by pulse-field gel electrophoresis and hybridized to DNA microarrays. Nine Assembly 19 supercontigs were found to contain markers from two different chromosomes. Assembly 21 contains the sequence of each of the eight chromosomes and was determined using a synteny analysis with preliminary versions of the Candida dubliniensis genome assembly, bioinformatics, a sequence tagged site (STS) map of overlapping fosmid clones, and an optical map. The orientation and order of the contigs on each chromosome, repeat regions too large to be covered by a sequence run, such as the ribosomal DNA cluster and the major repeat sequence, and telomere placement were determined using the STS map. Sequence gaps were closed by PCR and sequencing of the products. The overall assembly was compared to an optical map; this identified some misassembled contigs and gave a size estimate for each chromosome. CONCLUSION: Assembly 21 reveals an ancient chromosome fusion, a number of small internal duplications followed by inversions, and a subtelomeric arrangement, including a new gene family, the TLO genes. Correlations of position with relatedness of gene families imply a novel method of dispersion. The sequence of the individual chromosomes of C. albicans raises interesting biological questions about gene family creation and dispersion, subtelomere organization, and chromosome evolution.
  • Tamaki Cho, Toshihiro Aoyama, Mika Toyoda, Hironobu Nakayama, Hiroji Chibana, Hidenori Kaminishi
    Japanese Journal of Medical Mycology 48(4) 159-167 2007年  査読有り
    Quorum sensing through farnesol, a quorum sensing molecule, regulates virulence and morphogenesis in Candida albicans. Farnesol and high cell density of C. albicans repress hyphal formation in a minimal medium containing N-acetyl-D-glucosamine. Global transcription profiling at an early stage of quorum sensing by C. albicans in the N-acetyl-D-glucosamine medium was analyzed. Twenty-two of a total of 53 genes responded to both farnesol and high cell density. From in silico analysis and previous published data, nine of these genes including those encoding amino acid biosynthesis were controlled by the Gcn4p regulator. Nine other genes which included genes encoding central carbon metabolism were controlled by negative regulators including Nrg1p, Tup1p, Ssn6p, and/or Mig1p. Other genes not controlled by these regulators included genes related to oxidative stress, glucose metabolism, and agglutination. Expression of genes related to amino acid biosynthesis and central carbon metabolism in this study is similar to a previous report of transcription profiling in C. albicans following its internalization by phagocyte cells and adaptation to host challenges.
  • Takako Iwata, Hisao Hattori, Hiroji Chibana, Yuzuru Mikami, Yasushi Tomita, Akihiko Kikuchi, Toshio Kanbe
    Journal of Dermatological Science 41(1) 43-54 2006年1月  査読有り

MISC

 275

共同研究・競争的資金等の研究課題

 27