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Yukiko Tomioka Masami Morimatsu Ken-ichi Nishijima Tatsufumi Usui Sayo Yamamoto Haruka Suyama Kinuyo Ozaki Toshihiro Ito Etsuro Ono 《Biochemical and biophysical research communications》2014
Tumor-associated MUC1 binds to Siglec-9, which is expected to mediate tumor cell growth and negative immunomodulation. We hypothesized that a soluble form of Siglec-9 (sSiglec-9) competitively inhibits a binding of MUC1 to its receptor molecules like human Siglec-9, leading to provide antitumor benefit against MUC1-expressing tumor, and generated transgenic mouse lines expressing sSiglec-9 (sSiglec-9 Tg). When mammary tumor cells expressing MUC1 were intraperitoneally transplanted into sSiglec-9 Tg, tumor proliferation was slower with the lower histological malignancy as compared with non-transgenic mice. The sSiglec-9 was detected in the ascites caused by the tumor in the sSiglec-9 Tg, and sSiglec-9 and MUC1 were often colocalized on surfaces of the tumor cells. PCNA immunohistochemistry also revealed the reduced proliferation of the tumor cells in sSiglec-9 Tg. In sSiglec-9 Tg with remarkable suppression of tumor proliferation, MUC1 expressions were tend to be reduced. In the ascites of sSiglec-9 Tg bearing the tumor, T cells were uniformly infiltrated, whereas aggregations of degenerative T cells were often observed in the non-transgenic mice. These results suggest that sSiglec-9 has an antitumor benefit against MUC1-expressing tumor in the transgenic mice, which may avoid the negative immunomodulation and/or suppress tumor-associated MUC1 downstream signal transduction, and subsequent tumor proliferation. 相似文献
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Yuki Fujii Shiho Tanaka Manami Otsuki Yasushi Hoshino Chinatsu Morimoto Takuya Kotani Yuko Harashima Haruka Endo Yasutaka Yoshizawa Ryoichi Sato 《Bioscience reports》2013,33(1)
Characterizing the binding mechanism of Bt (Bacillus thuringiensis) Cry toxin to the cadherin receptor is indispensable to understanding the specific insecticidal activity of this toxin. To this end, we constructed 30 loop mutants by randomly inserting four serial amino acids covering all four receptor binding loops (loops α8, 1, 2 and 3) and analysed their binding affinities for Bombyx mori cadherin receptors via Biacore. High binding affinities were confirmed for all 30 mutants containing loop sequences that differed from those of wild-type. Insecticidal activities were confirmed in at least one mutant from loops 1, 2 and 3, suggesting that there is no critical amino acid sequence for the binding of the four loops to BtR175. When two mutations at different loops were integrated into one molecule, no reduction in binding affinity was observed compared with wild-type sequences. Based on these results, we discussed the binding mechanism of Cry toxin to cadherin protein. 相似文献
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Jenny Chan Haruka Yamazaki Noboru Ishiyama Min-Duk Seo Tapas K. Mal Takayuki Michikawa Katsuhiko Mikoshiba Mitsuhiko Ikura 《The Journal of biological chemistry》2010,285(46):36092-36099
The three isoforms of the inositol 1,4,5-trisphosphate receptor (IP3R) exhibit distinct IP3 sensitivities and cooperativities in calcium (Ca2+) channel function. The determinants underlying this isoform-specific channel gating mechanism have been localized to the N-terminal suppressor region of IP3R. We determined the 1.9 Å crystal structure of the suppressor domain from type 3 IP3R (IP3R3SUP, amino acids 1–224) and revealed structural features contributing to isoform-specific functionality of IP3R by comparing it with our previously determined structure of the type 1 suppressor domain (IP3R1SUP). The molecular surface known to associate with the ligand binding domain (amino acids 224–604) showed marked differences between IP3R3SUP and IP3R1SUP. Our NMR and biochemical studies showed that three spatially clustered residues (Glu-20, Tyr-167, and Ser-217 in IP3R1 and Glu-19, Trp-168, and Ser-218 in IP3R3) within the N-terminal suppressor domains of IP3R1SUP and IP3R3SUP interact directly with their respective C-terminal fragments. Together with the accompanying paper (Yamazaki, H., Chan, J., Ikura, M., Michikawa, T., and Mikoshiba, K. (2010) J. Biol. Chem. 285, 36081–36091), we demonstrate that the single aromatic residue in this region (Tyr-167 in IP3R1 and Trp-168 in IP3R3) plays a critical role in the coupling between ligand binding and channel gating. 相似文献
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Haruka Takagi Katsunori Kimoto Tetsuichi Fujiki Kazuyoshi Moriya 《Symbiosis (Philadelphia, Pa.)》2018,76(1):25-39
Several foraminifers found in warm and low-nutrient ocean surface water have photosynthetic algae as endosymbionts (photosymbiosis). To understand the trophic interactions, we studied Globigerinoides sacculifer, a spinose planktic foraminifer that has a dinoflagellate endosymbiont. We controlled two nutritional factors, feeding and inorganic nutrients in the seawater. The growth of the host and the symbionts and the photophysiological parameters were monitored under four experimental conditions. The results demonstrated that the holobionts primarily relied on phagotrophy for growth. The foraminifers grew considerably, and the chlorophyll a content per foraminifer, which is an indicator of the symbiont population, increased in the fed groups, but not in the unfed groups. The nutrient-rich seawater used for some of the cultures made no difference in either the growth or photophysiology of the holobionts. These observations indicated that the symbionts mainly utilized metabolites from the hosts for photosynthesis rather than inorganic nutrients in the seawater. Additionally, we observed that the symbionts in the starved hosts maintained their photosynthetic capability for at least 12 days, and that the hosts maintained at least some symbionts until gametogenesis was achieved. This suggests that the hosts have to retain the symbionts as an energy source for reproduction. The symbionts may also play an indispensable role in the metabolic activities of the hosts including waste transport or essential compound synthesis. Overall, our results revealed a novel mode of photosymbiosis in planktic foraminifers which contrasts with that found in benthic photosymbiotic foraminifers and corals. 相似文献
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Yukinori Yabuta Haruka Mukoyama Yoshimi Kaneda Narisa Kimura Tomohiro Bito Tsuyoshi Ichiyanagi 《Bioscience, biotechnology, and biochemistry》2018,82(9):1584-1590
Streptococcus mutans is a bacterium found in human oral biofilms (dental plaques) that is associated with the development of dental caries. Glucosyltransferases (GTFs) are key enzymes involved in dental plaque formation, and compounds that inhibit their activities may prevent dental caries. We developed a screening system for GTF-inhibitory activities, and used it to profile 44 types of herbal tea extracts. Lemon myrtle (Backhousia citriodora) extract exhibited the highest GTF-inhibitory activity, with an IC50 for GTF in solution of 0.14 mg mL?1. Furthermore, lemon myrtle extracts had the third-highest polyphenol content of all tested extracts, and strongly inhibited S. mutans biofilm. Interestingly, lemon myrtle extracts did not inhibit cell growth. 相似文献
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Andressa C. S. Nakagawa Haruka Itoyama Yuri Ariyoshi Nobuyuki Ario Yuki Tomita Yukari Kondo Mari Iwaya-Inoue Yushi Ishibashi 《Acta Physiologiae Plantarum》2018,40(6):111
Soybean seeds have high lipid and protein contents. Adverse environmental conditions restrict seed yield and quality. We examined the changes in storage compounds caused by drought stress from R5 stage (beginning seed growth stage). Under drought stress, contents of lipid in seed were remarkably low compared to control at 24 and 29 days after treatment. Protein contents in seed were immediately decreased after water deficit treatment. On the other hand, soluble sugar contents in seed were increased by drought stress. Drought stress decreased the expression of genes involved in lipid biosynthesis (PK, BCCP2, and KAS1) and increased the genes expression involved in lipid degradation (ACX2, MS, and PEPCK). These results suggest that the increasing of sugar content in seed under drought stress was complemented by degradation of lipids. The expressions of genes encoding storage protein (Gy4 and β-conglycinin) were also decreased by drought stress. This study showed how drought stress during seed filling affects seed quality, especially lipid and protein contents, that may facilitate further research on seed storage compounds metabolism under environmental stresses. 相似文献
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Role of transpiration from fruits in phloem transport and fruit growth in tomato fruits 总被引:1,自引:0,他引:1
Sink activity of fruits had been suggested to vary depending on transpiration of fruits. In this study, the effect of transpiration on dry matter accumulation was evaluated in tomato ( Lycopersicon esculentum Mill.). Fruits of cv. Saturn at 14 days after anthesis were enclosed in chambers and aerated with dried (<15% RH) or moistened (>90% RH) air. These treatments did not cause any significant differences in fruit fresh weight, dry weight, percentage of dry matter, and concentration of soluble sugars within 5 days of the treatment, or the import of 14 C within 18 h after the application of 14 CO2 to the source leaves. However, displacement transducer measurement of each fruit showed a 40% reduction in growth rate in response to exchange of moistened air with dried air. When fruits of cv. Momotaro were exposed to transpiration treatments from the beginning of visible fruit enlargement until the ripening stage, the fruits exhibited 20% reduction in growth and lower accumulation of dry matter at harvest following treatment with dried air. These results suggested that higher transpiration reduced both water accumulation and dry matter accumulation. In contrast, when fruit growth was mechanically restricted by enclosing the fruits in a chamber packed with glass beads, and dried or moistened air was passed through the spaces between the glass beads, fruits exhibited higher dry matter accumulation under dried air treatment conditions. The results show that only under artificial conditions would transpiration of fruits potentially drive carbohydrate transport; it does not serve as a limiting step of carbohydrate transport to tomato fruits under normal circumstances. 相似文献