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991.
Ishii K Hisaeda H Duan X Imai T Sakai T Fehling HJ Murata S Chiba T Tanaka K Hamano S Sano M Yano A Himeno K 《Microbes and infection / Institut Pasteur》2006,8(4):1045-1053
The ubiquitin-proteasome system (UPS) plays an indispensable role in inducing MHC class I-restricted CD8+ T cells and was exploited in the development of a DNA vaccine against the intracellular protozoan Toxoplasma gondii by constructing a chimeric DNA encoding a fusion protein between murine ubiquitin and the toxoplasma antigen SAG1. The SAG1 peptide was promptly degraded in antigen-presenting cells (APCs) transfected with the chimeric DNA. Degradation, however, was hampered by incubating the APCs with the proteasome inhibitor epoxomicin. Mice vaccinated with the DNA acquired potent protective immunity mediated by MHC class I-restricted CD8+ T cells against infection by the highly virulent Toxoplasma. The accelerated degradation and induction of immunity were dependent on the UPS since mice lacking an immuno-subunit of 20S proteasome, LMP7, lost these functions, although they were independent of the proteasome regulator PA28alpha/beta complex. 相似文献
992.
Efficient Antibody Production upon Suppression of O Mannosylation in the Yeast Ogataea minuta 下载免费PDF全文
Kousuke Kuroda Kazuo Kobayashi Yoshinori Kitagawa Taishiro Nakagawa Haruhiko Tsumura Toshihiro Komeda Daisuke Shinmi Eiji Mori Kazuhiro Motoki Kazumi Fuju Teruyuki Sakai Koichi Nonaka Takeshi Suzuki Kimihisa Ichikawa Yasunori Chiba Yoshifumi Jigami 《Applied microbiology》2008,74(2):446-453
When antibodies were expressed in the methylotrophic yeast Ogataea minuta, we found that abnormal O mannosylation occurred in the secreted antibody. Yeast-specific O mannosylation is initiated by the addition of mannose at serine (Ser) or threonine (Thr) residues in the endoplasmic reticulum via protein O mannosyltransferase (Pmt) activity. To suppress the addition of O-linked sugar chains on antibodies, we examined the possibility of inhibiting Pmt activity by the addition of a Pmt inhibitor during cultivation. The Pmt inhibitor was found to partially suppress the O mannosylation on the antibodies. Surprisingly, the suppression of O mannosylation was associated with an increased amount of assembled antibody (H2L2) and enhanced the antigen-binding activity of the secreted antibody. In this study, we demonstrated the expression of human antibody in O. minuta and elucidated the relationship between O mannosylation and antibody production in yeast. 相似文献
993.
Tomoko Sakai Mie Matsui Akichika Mikami Ludise Malkova Yuzuru Hamada Masaki Tomonaga Juri Suzuki Masayuki Tanaka Takako Miyabe-Nishiwaki Haruyuki Makishima Masato Nakatsukasa Tetsuro Matsuzawa 《Proceedings. Biological sciences / The Royal Society》2013,280(1753)
Developmental prolongation is thought to contribute to the remarkable brain enlargement observed in modern humans (Homo sapiens). However, the developmental trajectories of cerebral tissues have not been explored in chimpanzees (Pan troglodytes), even though they are our closest living relatives. To address this lack of information, the development of cerebral tissues was tracked in growing chimpanzees during infancy and the juvenile stage, using three-dimensional magnetic resonance imaging and compared with that of humans and rhesus macaques (Macaca mulatta). Overall, cerebral development in chimpanzees demonstrated less maturity and a more protracted course during prepuberty, as observed in humans but not in macaques. However, the rapid increase in cerebral total volume and proportional dynamic change in the cerebral tissue in humans during early infancy, when white matter volume increases dramatically, did not occur in chimpanzees. A dynamic reorganization of cerebral tissues of the brain during early infancy, driven mainly by enhancement of neuronal connectivity, is likely to have emerged in the human lineage after the split between humans and chimpanzees and to have promoted the increase in brain volume in humans. Our findings may lead to powerful insights into the ontogenetic mechanism underlying human brain enlargement. 相似文献
994.
Zin’ichi Karube Yoichiro Sakai Tomohiro Takeyama Noboru Okuda Ayato Kohzu Chikage Yoshimizu Toshi Nagata Ichiro Tayasu 《Ecological Research》2010,25(4):847-855
Carbon and nitrogen stable isotope ratios (δ13C and δ15N) of macroinvertebrates inhabiting littoral zones of lakes can serve as useful indicators of material loading from the watershed. We collected snails (Semisulcospira spp.) and bivalves (Unio douglasiae biwae Kobelt) from 29 littoral sites in Lake Biwa near the mouths of river tributaries with various human population density (HPD) and land-use patterns. The δ13C and δ15N signatures were determined for three potential food sources: particulate organic matter in the pelagic zone (PPOM), riverine particulate organic matter from tributaries (RPOM) and epilithic organic matter in the littoral zone (EOM). The stable isotope mixing model revealed that snails relied mainly on EOM, and bivalves on PPOM and RPOM. Multiple regression analysis showed that intersite variation in δ15N for snails was best explained by HPD, while variation in δ15N of EOM and nitrate was explained to a lesser extent by HPD. Comparison with isotope signatures of their food sources and riverine nutrients revealed that snails assimilated anthropogenic nitrogen from wastewater in the watershed. Our results also showed that the δ13C value of bivalves was marginally related to the fraction of paddy fields in the watersheds. In conclusion, the isotope signatures of macroinvertebrates inhabiting the littoral zone can be useful indicators of anthropogenic impacts from the watershed. 相似文献
995.
Noriyuki Yuasa Wei Zhang Tomohiro Goto Hiroyuki Sakaue Ayano Matsumoto-Takasaki Miyo Kimura Hiroya Ohshima Yasunobu Tsuchida Tomoyuki Koizumi Keiko Sakai Takumi Kojima Kazuo Yamamoto Munehiro Nakata Yoko Fujita-Yamaguchi 《The Journal of biological chemistry》2010,285(40):30587-30597
Anti-mannotriose (Man3) antibodies were previously isolated from a Keio phage library displaying human single chain variable fragments (scFvs) using a neoglycolipid, Man3- dipalmitoylphosphatidylethanolamine. Of three genes constructed, the 5A3 clone was expressed in mouse myeloma NS0 cells as a conjugate with human IgG1 Fc (scFv-Fc) and characterized (Sakai, K., Shimizu, Y., Chiba, T., Matsumoto-Takasaki, A., Kusada, Y., Zhang, W., Nakata, M., Kojima, N., Toma, K., Takayanagi, A., Shimizu, N., and Fujita-Yamaguchi, Y. (2007) Biochemistry 46, 253–262; Zhang, W., Matsumoto-Takasaki, A., Kusada, Y., Sakaue, H., Sakai, K., Nakata, M., and Fujita-Yamaguchi, Y. (2007) Biochemistry 46, 263–270). Similarly, anti-Lex phages were screened from the same library with lacto-N-fucopentaose III (LNFPIII; Lex)-dipalmitoylphosphatidylethanolamine. Of five phage clones isolated, two scFv genes were constructed to express scFv-Fc proteins in NS0 cells. As was experienced with anti-Man3 scFv-Fc clones, only one anti-LNFPIII clone, 1F12, was successfully produced and purified as an scFv-Fc protein. Although anti-LNFPIII 1F12 and anti-Man3 5A3 scFv-Fc proteins were secreted into media, a decline in scFv-Fc production was observed with both stable clones during early passages. Transient expression of anti-LNFPIII and anti-Man3 scFv-Fc genes in COS-7 cells and subsequent analyses of scFv-Fc protein expression revealed accumulation of translated proteins in the endoplasmic reticulum for scFv-Fc proteins derived from clones that did not survive as stable clones. This report describes the following: (i) isolation of anti-LNFPIII scFv genes; (ii) purification of anti-LNFPIII scFv-Fc proteins from stably and transiently expressed cells; and (iii) extracellular or intracellular localization of two anti-LNFPIII and three anti-Man3 scFv-Fc proteins. The results suggest that expression of anti-Man3 and other anti-carbohydrate antibodies in mammalian cells is disadvantageous for cell growth. 相似文献
996.
Recently, reef-building coral populations have been decreasing worldwide due to various disturbances. Population genetic studies are helpful for estimating the genetic connectivity among populations of marine sessile organisms with metapopulation structures such as corals. Moreover, the relationship between latitude and genetic diversity is informative when evaluating the fragility of populations. In this study, using highly variable markers, we examined the population genetics of the broadcast-spawning coral Acropora digitifera at 19 sites in seven regions along the 1,000 km long island chain of Nansei Islands, Japan. This area includes both subtropical and temperate habitats. Thus, the coral populations around the Nansei Islands in Japan are northern peripheral populations that would be subjected to environmental stresses different from those in tropical areas. The existence of high genetic connectivity across this large geographic area was suggested for all sites (F
ST≤0.033) although small but significant genetic differentiation was detected among populations in geographically close sites and regions. In addition, A. digitifera appears to be distributed throughout the Nansei Islands without losing genetic diversity. Therefore, A. digitifera populations in the Nansei Islands may be able to recover relatively rapidly even when high disturbances of coral communities occur locally if populations on other reefs are properly maintained. 相似文献
997.
The 70-kDa protoxin of Cry11A, a dipteran-specific insecticidal protein, was processed by trypsin into 36- and 32-kDa fragments. To investigate the potent function of the two processed fragments, a GST (Glutathione-S-transferase) fusion protein of each polypeptide was constructed. While neither the 36- nor the 32-kDa fragment was toxic to Culex pipiens larvae, coexpression of the two fragments restored the insecticidal activity. Furthermore, the coprecipitation experiment demonstrated that the 36-kDa fragment was associated with the 32-kDa fragment. It was, therefore, shown that the coexistence of the two processed fragments of Cry11A was essential for the toxicity. The mutant of the 36-kDa fragment lacking the region from Gly(257) to Arg(360) bound to the 32-kDa fragment but the coexpression with the 32-kDa fragment resulted in no toxicity, suggesting that this region was involved in insecticidal activity. 相似文献
998.
Masahito Shimizu Yohei Shirakami Hiroyasu Sakai Yoichi Yasuda Masaya Kubota Seiji Adachi Hisashi Tsurumi Yukihiko Hara Hisataka Moriwaki 《Chemico-biological interactions》2010,185(3):247-252
(?)-Epigallocatechin gallate (EGCG), the major constituent of green tea, inhibits the growth of colorectal cancer cells by inhibiting the activation of various types of receptor tyrosine kinases (RTKs). The RTK vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis induces tumor angiogenesis in colorectal cancer. This study examined the effects of EGCG on the activity of the VEGF/VEGFR axis and the expression of hypoxia-inducible factor (HIF)-1α, which promotes angiogenesis by elevating VEGF levels, in human colorectal cancer cells. Total and phosphorylated (i.e., activated) form (p-VEGFR-2) of VEGFR-2 proteins were overexpressed in a series of human colorectal cancer cell lines. Within 3 h, EGCG caused a decrease in the expression of HIF-1α protein and VEGF, HIF-1α, insulin-like growth factor (IGF)-1, IGF-2, epidermal growth factor (EGF), and heregulin mRNAs in SW837 colorectal cancer cells, which express a constitutively activated VEGF/VEGFR axis. A decrease was also observed in the expression of VEGFR-2, p-VEGFR-2, p-IGF-1 receptor, p-ERK, and p-Akt proteins within 6 h after EGCG treatment. Drinking EGCG significantly inhibited the growth of SW837 xenografts in nude mice, and this was associated with the inhibition of the expression and activation of VEGFR-2. The consumption of EGCG also inhibited activation of ERK and Akt, both of which are downstream signaling molecules of the VEGF/VEGFR axis, and reduced the expression of VEGF mRNA in xenografts. These findings suggest that EGCG may exert, at least in part, growth-inhibitory effects on colorectal cancer cells by inhibiting the activation of the VEGF/VEGFR axis through suppressing the expression of HIF-1α and several major growth factors. EGCG may therefore be useful in the chemoprevention and/or treatment of colorectal cancer. 相似文献
999.
Shirai Y Morioka S Sakuma M Yoshino K Otsuji C Sakai N Kashiwagi K Chida K Shirakawa R Horiuchi H Nishigori C Ueyama T Saito N 《Molecular biology of the cell》2011,22(8):1340-1352
During differentiation, keratinocytes undergo a dramatic shape change from small and round to large and flat, in addition to production of proteins necessary for the formation of epidermis. It has been shown that protein kinase C (PKC) η is crucial for keratinocyte differentiation. However, its role in this process has yet to be fully elucidated. Here, we show that catalytic activity is not necessary for enlarged and flattened morphology of human keratinocytes induced by overexpression of PKCη, although it is important for gene expression of the marker proteins. In addition, we identify the small G protein RalA as a binding partner of PKCη, which binds to the C1 domain, an indispensable region for the morphological change. The binding led activation of RalA and actin depolymerization associated with keratinocyte differentiation. siRNA techniques proved that RalA is involved in not only the keratinocyte differentiation induced by PKCη overexpression but also normal keratinocyte differentiation induced by calcium and cholesterol sulfate. These results provide a new insight into the molecular mechanism of cytoskeletal regulation leading to drastic change of cell shape. 相似文献
1000.
Oe K Ueha T Sakai Y Niikura T Lee SY Koh A Hasegawa T Tanaka M Miwa M Kurosaka M 《Biochemical and biophysical research communications》2011,(1):148-152
Quasispecies is a remarkable characteristic of hepatitis C virus (HCV) and has profound roles in HCV biology and clinical practice. The understanding of HCV quasispecies behavior, in particular in acute HCV infection, is valuable for vaccine development and therapeutic interference. However, acute HCV infection is seldom encountered in clinic practice due to its silent onset. In the present study, we reported a unique case of de novo HCV infection associated with the transplantation of bone marrow from a HCV-positive donor. HCV quasispecies diversity was determined in both the donor and the recipient over a 4-year follow-up, accompanied with simultaneous measurement of HCV neutralizing antibody. Detailed genetic and phylogenetic analyses revealed a divergent quasispecies evolution, which was not related to dynamic changes of HCV neutralizing antibody. Instead, our data suggested an essential role of the fitness adaptation of founder viral population in driving such an evolutionary pattern. 相似文献