Department of Public Health (Suzuki Lab.)

Prolonged endoplasmic reticulum stress alters placental morphology and causes low birth weight

Kawakami T, Yoshimi M, Kadota Y, Inoue M, Sato M and Suzuki S.

Toxicol Appl Pharmacol. 2014 Mar 1;275(2):134-44.

Highlights

 •Maternal exposure to excessive ER stress induced preterm birth and IUGR.

•Prolonged excessive ER stress altered the formation of the placental labyrinth.

•ER stress decreased GLUT1 mRNA expression in the placenta, but increased GLUT3.

•ER stress-induced IUGR causes decreased glycogen and altered glucose transport.

Abstract

The role of endoplasmic reticulum (ER) stress in pregnancy remains largely unknown. Pregnant mice were subcutaneously administered tunicamycin (Tun), an ER stressor, as a single dose [0, 50, and 100 μg Tun/kg/body weight (BW)] on gestation days (GDs) 8.5, 12.5, and 15.5. A high incidence (75%) of preterm delivery was observed only in the group treated with Tun 100 μg/kg BW at GD 15.5, indicating that pregnant mice during late gestation are more susceptible to ER stress on preterm delivery. We further examined whether prolonged in utero exposure to ER stress affects fetal development. Pregnant mice were subcutaneously administered a dose of 0, 20, 40, and 60 μg Tun/kg from GD 12.5 to 16.5. Tun treatment decreased the placental and fetal weights in a dose-dependent manner. Histological evaluation showed the formation of a cluster of spongiotrophoblast cells in the labyrinth zone of the placenta of Tun-treated mice. The glycogen content of the fetal liver and placenta from Tun-treated mice was lower than that from control mice. Tun treatment decreased mRNA expression of Slc2a1/glucose transporter 1 (GLUT1), which is a major transporter for glucose, but increased placental mRNA levels of Slc2a3/GLUT3. Moreover, maternal exposure to Tun resulted in a decrease in vascular endothelial growth factor receptor-1 (VEGFR-1), VEGFR-2, and placental growth factor. These results suggest that excessive and exogenous ER stress may induce functional abnormalities in the placenta, at least in part, with altered GLUT and vascular-related gene expression, resulting in low infant birth weight.

Department of Biochemistry (Kuzuhara Lab.)

Suppression of increased blood glucose levels in mice by Awa-ban tea following oral administration of mono- and disaccharides

Miki Hiasa, Megumi Kurokawa, Hiroshi Akita, Masatomo Harada, Kengo Niki, Kana Ohta, Masaki Shoji, Noriko Echigo, Takashi Kuzuhara

Journal of Functional Foods8, 188–192 (2014).

Highlights
•Awa-ban tea suppressed blood glucose levels after administration of maltose in mice
•Awa-ban tea suppressed blood glucose levels after administration of sucrose in mice
•Awa-ban tea suppressed blood glucose levels after administration of glucose in mice
•Awa-ban tea suppressed the area under the curve (AUC) of blood glucose by 72–83%
•Awa-ban tea is an alternative functional beverage to prevent diabetes

 

Awa-ban tea is a uniquely flavored, pickled and anaerobically fermented tea found only in the Tokushima prefecture in the Shikoku region of Japan. Diabetes is a major health problem worldwide. Here, we report that Awa-ban tea suppressed the increase in blood glucose levels after oral administration of maltose, sucrose, or glucose in mice (n = 9–54). Awa-ban tea suppressed the area under the curve (AUC) of blood glucose by 72–83%. Thus, we propose that Awa-ban tea can be used as an alternative functional beverage for diabetes prevention.

 

Department of Molecular Nutrition and Toxicology (Himeno Lab.)

Interleukin-6 enhances manganese accumulation in SH-SY5Y cells: implications of the up-regulation of ZIP14 and the down-regulation of ZnT10.

Hitomi Fujishiro Mari Yoshida Yuka Nakano and Seiichiro Himeno

Metallomics, 6, 944-949 (2014).

Exposure to an excess amount of manganese causes neurological symptoms similar to Parkinson’s disease. Zinc transporters such as Zrt, Irt-related protein 8 (ZIP8), and ZIP14 have been shown to have affinities for Mn2+ as well as Zn2+, but their roles in Mn2+ uptake in neuronal cells remain unclear. Recent studies have shown that another zinc transporter ZnT10 may be involved in manganese excretion. Here we examined the roles of ZIP8, ZIP14, and ZnT10 in the transport of manganese in human SH-SY5Y neuroblastoma cells. The introduction of siRNA of ZIP14 decreased the uptake of Mn2+, suggesting a significant role of ZIP14 in Mn2+ uptake in SH-SY5Y cells. The pretreatment of SH-SY5Y cells with interleukin-6 (IL-6) markedly increased the accumulation of manganese to approx. 3-fold that of the control, which could be partly explained by the increased uptake of Mn2+ due to the up-regulation of ZIP14 by IL-6. The treatment of SH-SH5Y cells with IL-6 clearly decreased both the mRNA and protein levels of ZnT10 with a concomitant decrease in the manganese excretion efficiency. These results suggest that both the up-regulation of ZIP14 and the down-regulation of ZnT10 by IL-6 might have enhanced the accumulation of manganese in SH-SY5Y cells. Our results provide new insight into the roles of zinc transporters in the aberrant manganese accumulation in neuronal cells, particularly in the presence of inflammatory cytokines such as IL-6.

 

Department of Microbiology (Nagahama Lab.)

Intracellular trafficking of Clostridium botulinum C2 toxin.

 

Masahiro Nagahama, Chihiro Takahashi, Kouhei Aoyanagi, Ryo Tashiro, Keiko Kobayashi,
Yoshihiko Sakaguchi, Kazumi Ishidoh, Jun Sakurai

Toxicon, 82, 76-82 (2014).

Highlights

Clostridium botulinum C2 toxin (C2I and C2IIa) is delivered to early endosomes.
•The delivery of C2I to the cytoplasm occurs in early endosomes.
•C2IIa was sent back to the plasma membranes through recycling endosomes.

Abstract

Clostridium botulinum C2 toxin is a binary toxin composed of an enzymatic component (C2I) and binding component (C2II). The activated binding component (C2IIa) forms heptamers and the oligomer with C2I is taken up by receptor-mediated endocytosis. We investigated the intracellular trafficking of C2 toxin. When MDCK cells were incubated with C2I and C2IIa at 37 °C, C2I colocalized with C2IIa in cytoplasmic vesicles at 5 min, and C2I then disappeared (15 min incubation and later), and C2IIa was observed in the vesicles. Internalized C2I and C2IIa were transported to early endosomes. Some of both components were returned to the plasma membrane through recycling endosomes, whereas the rest of C2IIa was transported to late endosomes and lysosomes for degradation. Bafilomycin A1, an endosomal acidification inhibitor, caused the accumulation of C2IIa in endosomes, and both nocodazole and colchicine, microtubule-disrupting agents, restricted C2IIa’s movement in the cytosol. These results indicated that an internalized C2I and C2IIa complex was delivered to early endosomes, and that subsequent delivery of C2I to the cytoplasm occurred in early endosomes. C2IIa was either sent back to the plasma membranes through recycling endosomes or transported to late endosomes and lysosomes for degradation.

Department of Medicinal Chemistry (Tsunoda Lab.)

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Eur. J. Org. Chem 2013, 36, 8208-8213 (2013).

A Method to Prepare Optically Active Acyclic α-Benzyl Ketones by Thermodynamically Controlled Deracemization

Kaku, H., Imai, T., Kondo, R., Mamba, S., Watanabe, Y., Inai, M., Nishii, T., Horikawa, M., Tsunoda, T.

Thermodynamically controlled deracemization of some acyclic ketones bearing a chiral center at the position α to the carbonyl group was satisfactorily achieved. Acyclic ketones with high optical purities could be isolated after treatment of the racemic ketones with base in aqueous MeOH in the presence of (–)-(2R,3R)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[5.4]decane (1a). The efficiency of the deracemization was appreciably influenced by the ratio of H2O/MeOH used as solvent.

Department of Physical Chemistry (Fukuyama Lab.)

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Chem. Pharm. Bull.62, 122-124 (2014).

A New Spiroindene Pigment from the Medicinal Fungus Phellinus ribis

Miwa KuboYuhong LiuMami IshidaKenichi HaradaYoshiyasu Fukuyama

A new spiroindene pigment, phelliribsin A, was isolated from the medicinal fungus Phellinus ribis, and its structure was determined by two dimensional (2D)-NMR methods. Phelliribsin A is an unprecedented spiroindene compound, and was found to have cytotoxic activity against PC12 cells at a concentration of 30 µM.

Department of Analytical Chemistry (Tanaka Lab.)

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Heterocycles89, 1369-1391 (2014).
Reductive Cyclization Reactions to Bicyclic Compounds Using Samarium Diiodide

Motoo Tori and Masakazu Sono

This review covers reports on the one-electron reductive cyclization reactions affording bicyclic compounds, such as hydrindans, perhydronaphthalenes, perhydroguaianes, and other systems including five-, six-, seven-, and eight-membered carbocycles using SmI2. The substrate is aldehyde, ketone, or ester. The effect of additives, such as H2O, MeOH, HMPA, and NiI2, was studied. The mechanistic aspects recently investigated are also introduced.

Department of Physical Chemistry (Fukuyama Lab.)

 

47

Tetrahedron, 69, 6959-6968 (2013).

Total Synthesis of Riccardin C and (±)-Cavicularin via Pd-Catalyzed Ar-Ar Corss Couplings.
K. Harada, K. Makino, N. Shima, H. Okuyama, T. Esumi, M. Kubo, H. Hioki, Y. Asakawa, Y. Fukuyama.

Riccardin C, a specific LXR α agonist, is a representative macrocyclic bisbibenzyl-type natural product. As part of our synthetic studies on macrocyclic bisbibenzyls, the synthesis of riccardin C and its analog cavicularin was examined. The total synthesis of riccardin C was accomplished via a Pd-catalyzed intramolecular Suzuki-Miyaura coupling as the key macrocyclization step. This synthetic strategy was also extended in the synthesis of (±)-cavicularin, which was then attained by constructing the dihydrophenanthrene moiety using a Pd-catalyzed Ar-Ar coupling reaction.

Department of Chemistry of Functional Molecule (Imagawa Lab.)

 

J Med Chem (2013) 56, 381-385

Development of Vizantin, a Safe Immunostimulant, based on the Structure-Activity Relationship of Trehalose-6,6’-Dicorynomycolate

Yamamoto, Hirofumi; Oda, Masataka; Nakano, Mayo; Watanabe, Naoyuki; Yabiku, Kenta; Shibutani, Masahiro; Inoue, Masahisa; Imagawa, Hiroshi; Nagahama, Masahiro; Himeno, Seiichiro ; Setsu, Kojun; Sakurai, Jun; Nishizawa, Mugio

 

Bacterial components, including Trehalose 6,6’-dimycolates (TDMs), have attracted considerable attention as lead compounds for adjuvant development. However, these compounds can result in clinical symptoms of septic shock, making it imperative to design suitable ‘safe’ immunostimulants that can activate the immune response without causing toxicity. In this article, we describe the development of Vizantin, 6,6’-bis-O-(3-nonyldodecanoyl)-α,α’-trehalose, on the basis of a structure-activity relationship study (SARs) with trehalose 6,6’-dicorynomycolate (TDCM). Our results show that it was easier to synthesize Vizantin on a large scale. Further it exhibited a more potent prophylactic effect on experimental lung metastasis of B16-F0 melanoma cells and could also stimulate human macrophages, making it a promising candidate as an adjuvant in clinical applications.

 

Department of Microbiology (Nagahama Lab.)

 

Clostridium perfringens Alpha-toxin Recognizes the GM1a-TrkA Complex

 

Masataka Oda, Michiko KaburaTeruhisa TakagishiAyaka SuzueKaori TominagaShiori UranoMasahiro NagahamaKeiko KobayashiKeiko FurukawaKoichi Furukawa and
Jun Sakurai

J Biol Chem (2012) 287, 33070-33079

Clostridium perfringens alpha-toxin is the major virulence factor in the pathogenesis of gas gangrene. Alpha-toxin is a 43-kDa protein with 2 structural domains: the N-domain contains the catalytic site and coordinates the divalent metal ions, and the C-domain is a membrane-binding site. The role of the exposed loop region (72-93 residues) in the N-domain, however, has been unclear. Here, we show that this loop contains a ganglioside-binding motif (H…SxWY…G), which is the same motif seen in botulinum neurotoxin, and directly binds to a specific conformation of the ganglioside GM1a through a carbohydrate moiety. Confocal microscopy analysis using fluorescently labeled BODIPY-GM1a revealed that the toxin colocalized with GM1a and induced clustering of GM1a on the cell membranes. Alpha-toxin was only slightly toxic in b1,4-N-acetylgalactosaminyltransferase knockout mice, which lack the a-series gangliosides that contain GM1a, but was highly toxic in α2,8-sialyltransferase knockout mice, which lack both b-series and c-series gangliosides, similar to the control mice. Moreover, experiments with site-directed mutants indicated that Trp-84 and Tyr-85 in the exposed alpha-toxin loop play an important role in the interaction with GM1a and subsequent activation of TrkA. These results suggest that binding of alpha-toxin to GM1a facilitates the activation of the TrkA receptor and induces a signal transduction cascade that promotes the release of chemokines. Therefore, we conclude that GM1a is the primary cellular receptor for alpha-toxin, which can be a potential target for drug developed against this pathogen.