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211.
Herein, we present the efficient cellular uptake of immobilized virus-like particles (VLPs) made of recombinant JC virus capsid proteins. VLPs expressed in Escherichia coli were labeled with fluorescein isothiocyanate (FITC). We compared two approaches for the cellular uptake of the FITC-VLPs. In the first approach, FITC-VLPs were immobilized on a polystyrene substrate, and then NIH3T3 cells were cultured on the same substrate. In the second approach, cells were cultured on a polystyrene substrate, and FITC-VLPs were then added to the cell culture medium. Flow cytometric analysis and confocal laser microscopic observation revealed that immobilized VLPs were incorporated into the cells with higher efficiency than were the diffusive VLPs suspended in solution. The cellular uptake of VLPs on the substrate was increased in a VLP density-dependent manner. As a control, disassembling VLPs to form VP1 pentamers abolished incorporation into the cells. Displaying sialic acid on the substrate enhanced VLP density through the specific affinities between the VLPs and sialic acid, resulting in efficient incorporation into the seeded cells. These techniques can be applied to the development of novel drug delivery systems and cell microarrays not only of nucleic acids but also of small molecules and proteins through their encapsulation in VLPs. 相似文献
212.
Okano Y Asada M Fujimoto A Ohtake A Murayama K Hsiao KJ Choeh K Yang Y Cao Q Reichardt JK Niihira S Imamura T Yamano T 《American journal of human genetics》2001,68(4):1036-1042
Galactokinase (GALK) deficiency is an autosomal recessive disorder characterized by hypergalactosemia and cataract formation. Through mass screening of newborn infants, we identified a novel and prevalent GALK variant (designated here as the "Osaka" variant) associated with an A198V mutation in three infants with mild GALK deficiency. GALK activity and the amount of immunoreactive protein in the mutant were both 20% of normal construct in expression analysis. The K(m) values for galactose and ATP-Mg(2+) in erythrocytes with homozygous A198V were similar to those of the healthy adult control subjects. A population study for A198V revealed prevalences of 4.1% in Japanese and 2.8% in Koreans, lower incidence in Taiwanese and Chinese, no incidence in blacks and whites from the United States, and a significantly high frequency (7.8%; P < .023) in Japanese individuals with bilateral cataract. This variant probably originated in Japanese and Korean ancestors and is one of the genetic factors that causes cataract in elderly individuals. 相似文献
213.
Identification of a potent and nonpeptidyl ccr3 antagonist 总被引:4,自引:0,他引:4
Saeki T Ohwaki K Naya A Kobayashi K Ishikawa M Ohtake N Noguchi K 《Biochemical and biophysical research communications》2001,281(3):779-782
CCR3 is expressed in a variety of leukocyte subsets, especially eosinophils, and may be involved in allergic disorders such as atopic asthma. To clarify the pathophysiological roles of CCR3 in allergic disorders, we developed a nonpeptidyl CCR3 antagonist. This antagonist, which is referred to as "Compound X," that inhibited the binding of [(125)I]Eotaxin to CHO cells transfected with human CCR3 with an IC(50) value of 2.3 nM. In human eosinophils, Compound X also inhibited Eotaxin-induced increases in intracellular Ca(2+) concentrations and chemotaxis. Thus, Compound X appears to be a highly potent CCR3 antagonist. These findings suggest that Compound X may be a useful tool for elucidating the pathophysiological roles of CCR3 in a variety of allergic disorders. 相似文献
214.
Minami K Raymond C Martin-Moutot N Ohtake A Van Renterghem C Takahashi M Seagar MJ Mori Y Sato K 《FEBS letters》2001,491(1-2):127-130
As replacement of Thr(11) of omega-conotoxin MVIIC with Ala significantly reduced the affinity for both N- and P/Q-type calcium channels, we examined the effect of substitution at this position with other residues. Binding assays using rat cerebellar P2 membranes showed that the affinity is in the order of Leu>Val, aminobutyric acid, Thr>Asn&z.Gt;Ser, Ala, Asp, Phe, Tyr for N-type channels and Thr>Leu, Val, aminobutyric acid, Asn, Ser>Ala&z.Gt;Asp, Phe, Tyr for P/Q-type channels, suggesting that aliphatic amino acids with longer side chains are favorable for block of N-type channels. The effects of substitution were examined electrophysiologically in BHK cells expressing N-type Ca2+ channels. Inhibition of Ba2+ current by the analogs did not completely correlate with binding affinity, although binding to BHK cells was comparable to rat cerebellar membranes. 相似文献
215.
5-Hydroxy-4-oxo-L-norvaline depletes intracellular glutathione: a new modulator of drug resistance 总被引:1,自引:0,他引:1
Tagashira M Nozato N Isonishi S Okamoto A Ochiai K Ohtake Y 《Bioscience, biotechnology, and biochemistry》1999,63(11):1953-1958
To search for compounds that reverse the drug resistance induced by glutathione (GSH), an original screening system to detect intracellular GSH depleters was established. Among 8843 microbes derived from the soil samples tested, the extracts of two Streptomyces species named KS6701 and KS8846, lowered the intracellular GSH level of Saccharomyces cerevisiae 5 x 47. From both the microbes, 5-hydroxy-4-oxo-L-norvaline (HON) was isolated as the active compound. At a concentration of 50-100 micrograms/ml, HON also decreased the GSH/protein level of the human ovarian tumor cell line, 2008/C13*5.25 and reversed its resistance to cisplatin. We also investigated the mechanism of the depletion. HON had little effect on gamma-glutamylcysteine synthetase (gamma-GCS) or glutathione synthetase, but HON decreased the quantity of thiol substances when it was spontaneously reacted with them. This suggested that the GSH depletion by HON occurred through a mechanism different from that of buthionine sulfoximine, a selective gamma-GCS inhibitor. 相似文献
216.
Shitashiro M Kato J Fukumura T Kuroda A Ikeda T Takiguchi N Ohtake H 《Journal of biotechnology》2003,101(1):11-18
Bacterial aerotaxis (the movement of a cell toward oxygen) was evaluated for its potential use in detecting the toxicity of chemicals to microorganisms. The level of toxicity was determined by the concentration of test chemicals resulting in a 50% inhibition of aerotaxis of Pseudomonas aeruginosa PAO1 after 40 min of exposure. The aerotactic responses of P. aeruginosa were measured by using chemotaxis well chambers. Each clear acrylic chamber had a lower and upper well separated by a polycarbonate filter with a uniform pore size of 8.0 microm. To automatically detect bacterial cells that crossed the filter in response to a gradient of oxygen, P. aeruginosa PAO1 was marked with green fluorescent protein (GFP), and the GFP fluorescence intensity in the upper well was continuously monitored by using a fluorescence spectrometer. By using this technique, volatile chlorinated aliphatic compounds, including trichloroethylene (TCE), trichloroethane, and tetrachloroethylene, were found to be inhibitory to bacterial aerotaxis, suggesting their possible toxicity to microorganisms. We also examined more than 20 potential toxicants for their ability to inhibit the aerotaxis of P. aeruginosa. Based on these experimental results, we concluded that bacterial aerotaxis has potential for use as a fast and reliable indicator in assessing the toxicity of chemicals to microorganisms. 相似文献
217.
Ohtake H Ichikawa N Okada M Yamashita T 《Journal of immunology (Baltimore, Md. : 1950)》2002,168(5):2087-2090
Tyrosine phosphorylation in the cytoplasmic domains of FcepsilonRI by the Src family kinase Lyn initiates a signaling cascade leading to mast cell activation. In this study, we show that a recently identified transmembrane protein, Csk-binding protein (Cbp), also known as phospoprotein associated with glycosphingolipid-enriched microdomains (PAG), negatively regulates FcepsilonRI signaling. In rat basophilic leukemia (RBL)-2H3 cells, the levels of tyrosine phosphorylation of Cbp/PAG and its association with Csk, a negative regulator for Lyn, significantly elevate immediately after aggregation of FcepsilonRI. An overexpression of Cbp/PAG in RBL-2H3 cells inhibits FcepsilonRI-mediated cell activation. This is accompanied with decreased levels of tyrosine phosphorylation of FcepsilonRI, association of FcepsilonRI with Lyn, and FcepsilonRI-associated tyrosine kinase activity. These findings combined with the fact that Cbp/PAG, Lyn, and aggregated FcepsilonRI are localized to lipid rafts, suggest that upon FcepsilonRI aggregation Cbp/PAG down-regulates the receptor-associated Lyn activity through relocating Csk to rafts, thereby efficiently mediating feedback inhibition of FcepsilonRI signaling. 相似文献
218.
219.
Lee SO Kato J Nakashima K Kuroda A Ikeda T Takiguchi N Ohtake H 《Bioscience, biotechnology, and biochemistry》2002,66(6):1366-1369
The gene (empI) encoding an extracellular metal protease was isolated from a Pseudoalteromonas sp. strain A28 DNA library. The recombinant EmpI protein was expressed in E. coli and purified. Paper-disk assays showed that the purified protease had potent algicidal activity. A skim milk-polyacrylamide gel electrophoresis protease assay showed that the 38-kDa band of protease activity, which co-migrated with purified EmpI and was sensitive to 1,10-phenathroline, was detected in the extracellular supernatant of A28. 相似文献
220.