Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Yohei Ishibashi Last modified date:2020.07.31

Assistant Professor / Molecular Biosciences / Department of Bioscience and Biotechnology / Faculty of Agriculture

1. 石橋 洋平、伊東 信、平林 義雄, The sirtuin inhibitor cambinol reduces intracellular glucosylceramide with ceramide accumulation by inhibiting glucosylceramide synthase, Bioscience, Biotechnology, and Biochemistry , , 2020.07.
2. Ishibashi Y, Aoki K, Okino N, Hayashi M, Ito M, A thraustochytrid-specific lipase/phospholipase with unique positional specificity contributes to microbial competition and fatty acid acquisition from the environment, Scientific reports, 10.1038/s41598-019-52854-7, 9, 1, 2019.12.
3. Nutahara E, Abe E, Uno S, Ishibashi Y, Watanabe T, Hayashi M, Okino N, Ito M, The glycerol-3-phosphate acyltransferase PLAT2 functions in the generation of DHA-rich glycerolipids in Aurantiochytrium limacinum F26-b., PLoS One, 14(1):e0211164., 2019.01.
4. Takashi Watanabe, Ryo Sakiyama, Yuya Iimi, Satomi Sekine, Eriko Abe, Kazuko H. Nomura, Kazuya Nomura, Yohei Ishibashi, Nozomu Okino, Masahiro Hayashi, Makoto Ito, Regulation of TG accumulation and lipid droplet morphology by the novel TLDP1 in Aurantiochytrium limacinum F26-b, Journal of Lipid Research, 10.1194/jlr.M079897, 58, 12, 2334-2347, 2017.01, Thraustochytrids are marine single-cell protists that produce large amounts of PUFAs, such as DHA. They accumulate PUFAs in lipid droplets (LDs), mainly as constituent(s) of triacylglycerol (TG). We identified a novel protein in the LD fraction of Aurantiochytrium limacinum F26-b using 2D-difference gel electrophoresis. The protein clustered with orthologs of thraustochytrids; however, the cluster was evolutionally different from known PAT family proteins or plant LD protein; thus, we named it thraustochytrid-specific LD protein 1 (TLDP1). TLDP1 surrounded LDs when expressed as a GFP-tagged form. Disruption of the tldp1 gene decreased the content of TG and number of LDs per cell; however, irregular and unusually large LDs were generated in tldp1-deficient mutants. Although the level of TG synthesis was unchanged by the disruption of tldp1, the level of TG degradation was higher in tldp1-deficient mutants than in the WT. These phenotypic abnormalities in tldp1-deficient mutants were restored by the expression of tldp1. These results indicate that TLDP1 is a thraustochytrid-specific LD protein and regulates the TG accumulation and LD morphology in A. limacinum F26-b.—Watanabe, T., R. Sakiyama, Y. Iimi, S. Sekine, E. Abe, K. H. Nomura, K. Nomura, Y. Ishibashi, N. Okino, M. Hayashi, and M. Ito. Regulation of TG accumulation and lipid droplet morphology by the novel TLDP1 in Aurantiochytrium limacinum F26-b..
5. Nozomu Okino, Hiroyoshi Wakisaka, Yohei Ishibashi, Makoto Ito, Visualization of Endoplasmic Reticulum and Mitochondria in Aurantiochytrium limacinum by the Expression of EGFP with Cell Organelle-Specific Targeting/Retaining Signals, Marine Biotechnology, 10.1007/s10126-018-9795-7, 20, 2, 182-192, 2018.04, Thraustochytrids are single cell marine eukaryotes that produce large amounts of polyunsaturated fatty acids such as docosahexaenoic acid. In the present study, we report the visualization of endoplasmic reticulum (ER) and mitochondria in a type strain of the thraustochytrid, Aurantiochytrium limacinum ATCC MYA-1381, using the enhanced green fluorescent protein (EGFP) with specific targeting/retaining signals. We expressed the egfp gene with ER targeting/retaining signals from A. limacinum calreticulin or BiP/GRP78 in the thraustochytrid, resulting in the distribution of EGFP signals at the perinuclear region and near lipid droplets. ER-Tracker™ Red, an authentic fluorescent probe for the visualization of ER in mammalian cells, also stained the same region. We observed small lipid droplets generated from the visualized ER in the early growth phase of cell culture. Expression of the egfp gene with the mitochondria targeting signal from A. limacinum cytochrome c oxidase resulted in the localization of EGFP near the plasma membrane. The distribution of EGFP signals coincided with that of MitoTracker® Red CMXRos, which is used to visualize mitochondria in eukaryotes. The ER and mitochondria of A. limacinum were visualized for the first time by EGFP with thraustochytrid cell organelle-specific targeting/retaining signals. These results will contribute to classification of the intracellular localization of proteins expressed in ER and mitochondria as well as analyses of these cell organelles in thraustochytrids..
6. Yohei Ishibashi, Makoto Ito, Yoshio Hirabayashi, Regulation of glucosylceramide synthesis by Golgi-localized phosphoinositide, Biochemical and Biophysical Research Communications, 10.1016/j.bbrc.2018.04.039, 499, 4, 1011-1018, 2018.05, Phosphoinositides mediate a large number of signaling processes in mammalian cells. Here, we report that phophatidylinositol-4-phosphate (PtdIns(4)P) downregulates the cellular glucosylceramide (GlcCer) level by inhibiting the interaction between GlcCer synthase (UGCG) and UDP-glucose in the Golgi apparatus. In this study, we used two PH domain probes to bind phosphoinositides; one derived from FAPP1 for targeting to the Golgi PtdIns(4)P and the other from PLC δ for targeting to the plasma membrane PtdIns(4,5)P2. The levels of GlcCer and lactosylceramide, but not of sphingomyelin (SM), were increased following expression of the FAPP1 PH domain in cells, accompanied by an increase in UGCG activity. However, no elevated GlcCer level was observed after expression of the PLC δ PH domain. PtdIns(4)P inhibited UGCG activity, but not SMS activity, in a concentration-dependent manner, and UGCG activity was restored by the addition of UDP-glucose in the reaction mixture. These results indicate that PtdIns(4)P inhibits UGCG activity by competing with UDP-glucose. We conclude that the increase in UGCG activity due to the expression of the FAPP1 PH domain was caused by an attenuation of the inhibitory effect of PtdIns(4)P on UGCG. This study provides new insights into the regulation of GlcCer synthesis by PtdIns(4)P in the Golgi apparatus..
7. Takehiro Shinoda, Naoko Shinya, Kaori Ito, Yoshiko Ishizuka-Katsura, Noboru Osawa, Takaho Terada, Kunio Hirata, Yoshiaki Kawano, Masaki Yamamoto, Taisuke Tomita, Yohei Ishibashi, Yoshio Hirabayashi, Tomomi Kimura-Someya, Mikako Shirouzu, Shigeyuki Yokoyama, Cell-free methods to produce structurally intact mammalian membrane proteins, Scientific Reports, 10.1038/srep30442, 6, 2016.07.
8. Yohei Ishibashi, Yoshio Hirabayashi, AMP-activated Protein Kinase Suppresses Biosynthesis of Glucosylceramide by Reducing Intracellular Sugar Nucleotides, JOURNAL OF BIOLOGICAL CHEMISTRY, 10.1074/jbc.M115.658948, 290, 29, 18245-18260, 2015.07.
9. Yohei Ishibashi, Yusuke Nagamatsu, Tomofumi Miyamoto, Naoyuki Matsunaga, NOZOMU OKINO, Kuniko Yamaguchi, Makoto Ito, A novel ether-linked phytol-containing digalactosylglycerolipid in the marine green alga, Ulva pertusa., Biochem Biophys Res Commun, 10.1016/j.bbrc.2014.08.056., 452, 873-80, 2014.10, Galactosylglycerolipids (GGLs) and chlorophyll are characteristic components of chloroplast in photosynthetic organisms. Although chlorophyll is anchored to the thylakoid membrane by phytol (tetramethylhexadecenol), this isoprenoid alcohol has never been found as a constituent of GGLs. We here described a novel GGL, in which phytol was linked to the glycerol backbone via an ether linkage. This unique GGL was identified as an Alkaline-resistant and Endogalactosylceramidase (EGALC)-sensitive GlycoLipid (AEGL) in the marine green alga, Ulva pertusa. EGALC is an enzyme that is specific to the R-Galα/β1-6Galβ1-structure of galactolipids. The structure of U. pertusa AEGL was determined following its purification to 1-O-phytyl-3-O-Galα1-6Galβ1-sn-glycerol by mass spectrometric and nuclear magnetic resonance analyses. AEGLs were ubiquitously distributed in not only green, but also red and brown marine algae; however, they were rarely detected in terrestrial plants, eukaryotic phytoplankton, or cyanobacteria. .
10. Yohei Ishibashi, Utaro Kobayashi, Atsushi Hijikata, Keishi Sakaguchi, Hstsumi M Goda, Tomohiro Tamura, NOZOMU OKINO, Makoto Ito, Preparation and characterization of EGCase I, applicable to the comprehensive analysis of GSLs, using a rhodococcal expression system, J. Lipid Res., 10.1194/jlr.D028951, 53, 10, 2242-2251, 2012.10.
11. Yohei Ishibashi, Ayako Kohyama-Koganeya, Yoshio Hirabayashi, New insights on glucosylated lipids: metabolism and functions., Biochim Biophys Acta, 10.1016/j.bbalip.2013.06.001, 1831, 1475-1485, 2013.09, Ceramide, cholesterol, and phosphatidic acid are major basic structures for cell membrane lipids. These lipids are modified with glucose to generate glucosylceramide (GlcCer), cholesterylglucoside (ChlGlc), and phosphatidylglucoside (PtdGlc), respectively. Glucosylation dramatically changes the functional properties of lipids. For instance, ceramide acts as a strong tumor suppressor that causes apoptosis and cell cycle arrest, while GlcCer has an opposite effect, downregulating ceramide activities. All glucosylated lipids are enriched in lipid rafts or microdomains and play fundamental roles in a variety of cellular processes. In this review, we discuss the biological functions and metabolism of these three glucosylated lipids. .
12. Yohei Ishibashi, Kazutaka Ikeda, Keishi Sakaguchi, NOZOMU OKINO, Ryo Taguchi, Makoto Ito, Quality control of fungus-specific glucosylceramide in Cryptococcus neoformans by endoglycoceramidase-related protein 1 (EGCrP1)., J. Biol. Chem., 287, 1, 368-381, 2012.01.
13. Naoki Fujitani, Yasuhiro Takegawa, Yohei Ishibashi, Kayo Araki, Jun-ichi Furukawa, Susumu Mitsutake, Yasuyuki Igarashi, Makoto Ito, Yasuro Shinohara, Qualitative and Quantitative Cellular Glycomics of Glycosphingolipids Based on Rhodococcal Endoglycosylceramidase-assisted Glycan Cleavage, Glycoblotting-assisted Sample Preparation, and Matrix-assisted Laser Desorption Ionization Tandem Time-of-flight Mass Spectrometry Analysis, J. Biol. Chem., 10.1074/jbc.M111.301796, 286, 48, 41669-41679, 2011.12.
14. Yu-Teh Li, Chau-Wen Chou, Su-Chen Li, Utaro Kobayashi, Yohei Ishibashi, Makoto Ito, Preparation of homogenous oligosaccharide chains from glycosphingolipids, Glycoconjugate J., 10.1007/s10719-008-9125-9, 26, 8, 929-933, 2009.11.
15. Yohei Ishibashi, Yusuke Nagamatsu, Sandra Meyer, Akihiro Imamura, Hideharu Ishida, Makoto Kiso, NOZOMU OKINO, Rudolf Geyer, Makoto Ito, Transglycosylation-based fluorescent labeling of 6-gala series glycolipids by endogalactosylceramidase, Glycobiology, 10.1093/glycob/cwp051, 19, 7, 797-807, 2009.07.
16. Yohei Ishibashi, Toru Nakasone, Masashi Kiyohara, Yasuhiro Horibata, Keishi Sakaguchi, Atsushi Hijikata, Sachiyo Ichinose, Akira Omori, Yasuyuki Yasui, Akihiro Imamura, Hideharu Ishida, Makoto Kiso, NOZOMU OKINO, Makoto Ito, A novel endoglycoceramidase hydrolyzes oligogalactosylceramides to produce galactooligosaccharides and ceramides., J. Biol. Chem., 2007.04.
17. Yohei Ishibashi, Masahi Kiyohara, NOZOMU OKINO, Makoto Ito, Synthesis of fluorescent glycosphingolipids and neoglycoconjugates which contain 6-gala oligosaccharides using the transglycosylation reaction of a novel endoglycoceramidase (EGALC)., J. Biochem., 2007.08.