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排序方式: 共有133条查询结果,搜索用时 15 毫秒
1.
Masaki Saito Hiroyuki Tanaka Masako Sasaki Hitoshi Kurose Norimichi Nakahata 《Cellular signalling》2010,22(1):41-46
The physiological role of the thromboxane A2 (TXA2) receptor expressed on glial cells remains unclear. We previously reported that 1321N1 human astrocytoma cells pretreated with dibutyryl cyclic AMP (dbcAMP) became swollen in response to U46619, a TXA2 analogue. In the present study, we examined the detailed mechanisms of TXA2 receptor-mediated cell swelling in 1321N1 cells. The cell swelling caused by U46619 was suppressed by expression of p115-RGS, an inhibitory peptide of Gα12/13 pathway and C3 toxin, an inhibitory protein for RhoA. The swelling was also inhibited by treatment with Y27632, a Rho kinase inhibitor and 5-(ethyl-N-isopropyl)amiloride (EIPA), a Na+/H+-exchanger inhibitor. Furthermore, cell swelling was suppressed by the pretreatment with aquaporin inhibitors mercury chloride or phloretin in a concentration-dependent manner, suggesting that aquaporins are involved in U46619-induced 1321N1 cell swelling. In fact, U46619 caused [3H]H2O influx into the cells, which was inhibited by p115-RGS, C3 toxin, EIPA, mercury chloride and phloretin. This is the first report that the TXA2 receptor mediates water influx through aquaporins in astrocytoma cells via TXA2 receptor-mediated activation of Gα12/13, Rho A, Rho kinase and Na+/H+-exchanger. 相似文献
2.
PGJ2 and delta 12PGJ2 (1 microM to 30 microM) inhibited the growth of human astrocytoma cells (1321N1) in a time-dependent manner within 48 hrs, determined by [3H]thymidine incorporation into acid-insoluble fraction or amounts of protein. The EC50 values for PGJ2 and delta 12PGJ2 were approximately 8 microM and 6 microM, respectively. [3H]Thymidine incorporation to acid insoluble fraction was inhibited by these PGs within 1 hr, indicating that these PGs rapidly affect cell functions. Although it has been reported that an increase in cyclic AMP inhibits cell growth, PGJ2 and delta 12PGJ2, but not PGE1, reduced isoproterenol (10 microM)-induced accumulation of cyclic AMP, suggesting that PGJ2 and delta 12PGJ2 may disturb adenylate cyclase system, which might be independent on cell growth. On the other hand, these PGs inhibited the incorporation of [3H]inositol into phospholipid fraction within 6 hrs. Furthermore, PGJ2 and delta 12PGJ2 inhibited carbachol- and/or histamine-induced accumulation of inositol phosphates with a similar dose-dependency to their inhibitions of cell growth. In membrane preparations, however, PGJ2 and delta 12PGJ2 failed to inhibit GTP gamma S (10 microM)- nor Ca2+ (1 mM)-induced accumulation of inositol phosphates. The site of PGJ2 or delta 12PGJ2 in inhibition of inositol phosphate accumulation would not be phospholipase C nor a putative GTP binding protein involved in activation of phospholipase C. The present results indicate that PGJ2 and delta 12PGJ2 inhibit cell growth in human astrocytoma cells and the inhibition of phosphoinositide turnover by these PGs might be involved in the inhibition of cell growth. 相似文献
3.
Koji Ando Shigetomo Fukuhara Takahiro Moriya Yutaro Obara Norimichi Nakahata Naoki Mochizuki 《The Journal of cell biology》2013,202(6):901-916
Reorganization of the actin cytoskeleton is responsible for dynamic regulation of endothelial cell (EC) barrier function. Circumferential actin bundles (CAB) promote formation of linear adherens junctions (AJs) and tightening of EC junctions, whereas formation of radial stress fibers (RSF) connected to punctate AJs occurs during junction remodeling. The small GTPase Rap1 induces CAB formation to potentiate EC junctions; however, the mechanism underlying Rap1-induced CAB formation remains unknown. Here, we show that myotonic dystrophy kinase–related CDC42-binding kinase (MRCK)-mediated activation of non-muscle myosin II (NM-II) at cell–cell contacts is essential for Rap1-induced CAB formation. Our data suggest that Rap1 induces FGD5-dependent Cdc42 activation at cell–cell junctions to locally activate the NM-II through MRCK, thereby inducing CAB formation. We further reveal that Rap1 suppresses the NM-II activity stimulated by the Rho–ROCK pathway, leading to dissolution of RSF. These findings imply that Rap1 potentiates EC junctions by spatially controlling NM-II activity through activation of the Cdc42–MRCK pathway and suppression of the Rho–ROCK pathway. 相似文献
4.
Somatic cell mutation in pediatric patients undergoing allogeneic bone marrow transplantation 总被引:1,自引:0,他引:1
Hamahata K Kubota M Usami I Lin YW Shimizu K Morimoto A Nakahata T 《Mutation research》2002,517(1-2):21-28
In order to examine whether bone marrow transplantation (BMT) has genotoxic effects in vivo, mutant frequencies (Mfs) at the hypoxanthine-guanine phosphoribosyl transferase (Hprt) locus were evaluated. Thirty-seven pediatric patients who had received allogeneic BMT for various hematologic or immunologic disorders were enrolled. Nine out of the 37 patients (24.3%) were found to have Hprt-Mfs exceeding the 99% confidence limits calculated from observation of healthy controls. Among factors including gender, primary disease of the patient, donor-recipient histocompatibility relationship, age of donor, and total body irradiation as conditioning regimen, none was associated with an increased Hprt-Mf. In three patients who had chimerism in their peripheral blood after BMT, Hprt mutant clones turned out to be of donor- or recipient-origin. Mfs at the T-cell receptor (TCR) locus were examined in 28 patients. Four patients (14.3%) were found to have increased TCR-Mfs. However, there were not any patients who showed elevation of both Hprt-and TCR-Mfs. These data, taken together, suggest that BMT may cause genotoxicity in vivo in some patients. 相似文献
5.
Obara Y Nakahata N Mizushina Y Sugawara F Sakaguchi K Ohizumi Y 《Life sciences》2000,67(13):1659-1665
Fomitellic acid (FA) A and B are specific inhibitors of DNA polymerase alpha and beta. They showed cytotoxicity against rat pheochromocytoma cells (PC-12 cells) in a concentration-dependent manner. However, after PC-12 cells were cultivated with low concentrations of FAs, the cells extended neurites in greater degree similar to the cells cultivated with nerve growth factor. Another DNA polymerase alpha inhibitor, aphidicolin, also induced neurite outgrowth. Furthermore, PC-12 cells were strongly immunostained with anti-alpha-tubulin or anti-tau antibody after the treatment with FAs. These results suggest that weak inhibition of DNA polymerase activity induces the neurite outgrowth in PC-12 cells. 相似文献
6.
Tsukii K Nakahata N Tsurufuji S Ohizumi Y 《Canadian journal of physiology and pharmacology》1998,76(10-11):1024-1032
N-Formyl-Met-Leu-Phe (FMLP) and phorbol 12-myristate 13-acetate (PMA) caused a synergistic augmentation of superoxide anion (O2-) production in neutrophil-like HL-60 cells differentiated with dibutyryl cAMP. The present study was undertaken to investigate the mechanism of the synergistic augmentation of O2- production. FMLP increased intracellular free Ca2+ concentration ([Ca2+]i), which was slightly suppressed by PMA and completely inhibited by an intracellular Ca2+ chelating agent, O,O'-bis(2-aminophenyl)ethyleneglycol-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM). Although FMLP-induced O2- production was inhibited by BAPTA-AM, a major part of the synergistic augmentation of O2- production by FMLP and PMA remained after BAPTA-AM treatment, suggesting that a Ca2+-independent mechanism might be involved in the augmentation. FMLP and PMA caused an activation of phospholipase D (PLD) almost additively in a Ca2+-sensitive manner. The synergistic activation of mitogen-activated protein kinase (MAPK) was evoked by combined addition of PMA and FMLP in a BAPTA-AM resistant manner. However, PD98059, a MAPK kinase inhibitor, did not affect the synergistic augmentation of O2- production, although it potently inhibited the synergistic augmentation of tyrosine phosphorylation of MAPK. Wortmannin, a phosphatidylinositol 3-kinase inhibitor, inhibited FMLP-induced O2- production, but it did not inhibit the synergistic augmentation of O2- production by PMA and FMLP. In contrast, staurosporine and GF109203X, protein kinase C inhibitors, reduced the synergistic augmentation induced by PMA and FMLP. In addition, pertussis toxin (PT) abolished the synergistic augmentation of O2- production. It is concluded that the synergistic augmentation of O2- production induced by PMA and FMLP is mediated through a PT-sensitive G protein and a protein kinase C in a Ca2+-independent manner. 相似文献
7.
Kuniko Akama Tomoe Horikoshi Atsushi Sugiyama Satoko Nakahata Aoi Akitsu Nobuyoshi Niwa Atsushi Intoh Yasutaka Kakui Michiko Sugaya Kazuo Takei Noriaki Imaizumi Takaya Sato Rena Matsumoto Hitoshi Iwahashi Shin-ichi Kashiwabara Tadashi Baba Megumi Nakamura Tosifusa Toda 《Biochimica et Biophysica Acta - Proteins and Proteomics》2010,1804(6):1272-1284
In mammalian spermiogenesis, sperm mature during epididymal transit to get fertility. The pig sharing many physiological similarities with humans is considered a promising animal model in medicine. We examined the expression profiles of proteins from boar epididymal caput, corpus, and cauda sperm by two-dimensional gel electrophoresis and peptide mass fingerprinting. Our results indicated that protein disulfide isomerase-P5 (PDI-P5) human homolog was down-regulated from the epididymal corpus to cauda sperm, in contrast to the constant expression of protein disulfide isomerase A3 (PDIA3) human homolog. To examine the functions of PDIA3 and PDI-P5, we cloned and sequenced cDNAs of pig PDIA3 and PDI-P5 protein precursors. Each recombinant pig mature PDIA3 and PDI-P5 expressed in Escherichia coli showed thiol-dependent disulfide reductase activities in insulin turbidity assay. Although PDIA3 showed chaperone activity to promote oxidative refolding of reduced denatured lysozyme, PDI-P5 exhibited anti-chaperone activity to inhibit oxidative refolding of lysozyme at an equimolar ratio. SDS-PAGE and Western blotting analysis suggested that disulfide cross-linked and non-productively folded lysozyme was responsible for the anti-chaperone activity of PDI-P5. These results provide a molecular basis and insights into the physiological roles of PDIA3 and PDI-P5 in sperm maturation and fertilization. 相似文献
8.
Hiroshi Furuta Yuudai Kondo Shingo Nakahata Sumio Sakoda 《Biochemical and biophysical research communications》2010,391(4):1785-1791
Oral cancer is one of the most common cancers worldwide, and squamous-cell carcinoma (OSCC) is the most common phenotype of oral cancer. Although patients with OSCC have poor survival rates and a high incidence of metastasis, the molecular mechanisms of OSCC development have not yet been elucidated. This study investigated whether N-myc downstream-regulated gene 2 (NDRG2) contributes to the carcinogenesis of OSCC, as NDRG2 is reported to be a candidate tumor-suppressor gene in a wide variety of cancers. The down-regulation of NDRG2 mRNA, which was dependent on promoter methylation, was seen in the majority of OSCC cases and in several cases of precancerous leukoplakia with dysplasia. Induction of NDRG2 expression in an HSC-3/OSCC cell line significantly inhibited cell proliferation and decreased colony formation ability on soft agar. The majority of OSCC cell lines showed an activation of PI3K/Akt signaling, and enforced expression of NDRG2 in HSC-3 cells decreased the level of phosphorylated Akt at Serine 473 (p-Akt). Immunohistochemical p-Akt staining was detected in 56.5% of the OSCC tumors, and 80.4% of the tumors were negative for NDRG2 staining. Moreover, positive p-Akt staining was inversely correlated with decreased NDRG2 expression in OSCC tumors with moderate to poor differentiation (p < 0.005). Therefore, NDRG2 is a candidate tumor-suppressor gene for OSCC development and probably contributes to the tumorigenesis of OSCC partly via the modulation of Akt signaling. 相似文献
9.
Tatsutoshi Inuzuka Hironori Suzuki Masato Kawasaki Hideki Shibata Soichi Wakatsuki Masatoshi Maki 《BMC structural biology》2010,10(1):25
Background
ALG-2 (a gene product of PDCD6) belongs to the penta-EF-hand (PEF) protein family and Ca2+-dependently interacts with various intracellular proteins including mammalian Alix, an adaptor protein in the ESCRT system. Our previous X-ray crystal structural analyses revealed that binding of Ca2+ to EF3 enables the side chain of R125 to move enough to make a primary hydrophobic pocket (Pocket 1) accessible to a short fragment of Alix. The side chain of F122, facing a secondary hydrophobic pocket (Pocket 2), interacts with the Alix peptide. An alternatively spliced shorter isoform, designated ALG-2ΔGF122, lacks Gly121Phe122 and does not bind Alix, but the structural basis of the incompetence has remained to be elucidated. 相似文献10.
Marcotullio MC Pagiotti R Maltese F Oball-Mond Mwankie GN Hoshino T Obara Y Nakahata N 《Bioorganic & medicinal chemistry》2007,15(8):2878-2882
Two new cyathane diterpenes, cyrneine C (4) and D (5), were isolated from the mushroom Sarcodon cyrneus, along with previously isolated cyrneine A, B and glaucopine C. The structures of the novel diterpenoids were determined by the analysis of spectroscopic data. Effects of the cyrneines and glaucopine C on the NGF gene expression in 1321N1 cells and on neurite outgrowth on PC12 cells were evaluated. 相似文献