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991.
Yotsumoto F Yagi H Suzuki SO Oki E Tsujioka H Hachisuga T Sonoda K Kawarabayashi T Mekada E Miyamoto S 《Biochemical and biophysical research communications》2008,365(3):555-561
Aberrant expression levels of epidermal growth factor receptor (EGFR) and its cognate ligands have been recognized as one of the causes of cancer progression. To investigate the validity of EGFR ligands as targets for cancer therapy, we examined the expression of EGFR ligands and in vitro anti-tumor effects of small interference RNA (siRNA) for EGFR ligands in various cancer cells. HB-EGF expression was dominantly elevated in ovarian, gastric, and breast cancer, melanoma and glioblastoma cells, whereas amphiregulin was primarily expressed in pancreatic, colon, and prostate cancer, renal cell carcinoma and cholangiocarcinoma cells. Transfection of siRNAs for HB-EGF or amphiregulin into these cells significantly increased the numbers of apoptotic cells with attenuation of EGFR and ERK activation. In lung cancer cells, any EGFR ligand was not recognized as a validated target for cancer therapy. These results suggest that HB-EGF and amphiregulin are promising targets for cancer therapy. 相似文献
992.
Augustine AJ Kragh ME Sarangi R Fujii S Liboiron BD Stoj CS Kosman DJ Hodgson KO Hedman B Solomon EI 《Biochemistry》2008,47(7):2036-2045
The multicopper oxidases catalyze the 4e- reduction of O2 to H2O coupled to the 1e- oxidation of 4 equiv of substrate. This activity requires four Cu atoms, including T1, T2, and coupled binuclear T3 sites. The T2 and T3 sites form a trinuclear cluster (TNC) where O2 is reduced. The T1 is coupled to the TNC through a T1-Cys-His-T3 electron transfer (ET) pathway. In this study the two T3 Cu coordinating His residues which lie in this pathway in Fet3 have been mutated, H483Q, H483C, H485Q, and H485C, to study how perturbation at the TNC impacts the T1 Cu site. Spectroscopic methods, in particular resonance Raman (rR), show that the change from His to Gln to Cys increases the covalency of the T1 Cu-S Cys bond and decreases its redox potential. This study of T1-TNC interactions is then extended to Rhus vernicifera laccase where a number of well-defined species including the catalytically relevant native intermediate (NI) can be trapped for spectroscopic study. The T1 Cu-S covalency and potential do not change in these species relative to resting oxidized enzyme, but interestingly the differences in the structure of the TNC in these species do lead to changes in the T1 Cu rR spectrum. This helps to confirm that vibrations in the cysteine side chain of the T1 Cu site and the protein backbone couple to the Cu-S vibration. These changes in the side chain and backbone provide a possible mechanism for regulating intramolecular T1 to TNC ET in NI and partially reduced enzyme forms for efficient turnover. 相似文献
993.
The Japenese eel, Anguilla japonica, is generally assumed to be composed of a single population with wide distribution range, and some genetic studies using allozyme or mitochondrial DNA methods supported this population model. However, one genetic study suggested the existence of multiple populations in this species, and thus, more detailed studies on the population structure is needed. Here we characterized a total of 11 microsatellite markers of the Japanese eel. These will serve as powerful tools for detailed population study for the Japanese eel, though two of them showed the significant departure from the Hardy–Weinberg expectations. 相似文献
994.
Satoshi Iwao Nobuko Iwao Denis C. Muller Dariush Elahi Hiroshi Shimokata Reubin Andres 《Obesity (Silver Spring, Md.)》2001,9(11):685-695
Objectives: To examine the power of the combined measurements of body mass index (BMI) and waist circumference (WC) for the prediction of abnormality in coronary heart disease risk factors and to determine whether the additional measurement of WC is predictive in older men and women. Research Methods and Procedures: 1190 men and 751 women of the Baltimore Longitudinal Study of Aging were dichotomized into younger (<65 years) and older (65+ years) age groups. Coronary risk factors in the realms of glucose/insulin metabolism, blood pressure, and plasma lipids were assessed. The relationship of BMI and WC, singly and combined, to 10 risk factors for coronary heart disease was examined. Results: In younger and older men and women, BMI and WC are highly correlated (0.84 to 0.88). BMI and WC are also significantly correlated to all 10 coronary risk factors in younger men and women and to 8 of the 10 in the older men and women. Both partial correlation and logistic regression analyses revealed a modest but significant improvement in the prediction of coronary risk in younger men and women by WC after controlling for the level of BMI. There was no improvement in the older subjects. Discussion: WC adds only modestly to the prediction of coronary risk in younger subjects once BMI is known, and adds nothing to the production of risk in older subjects. 相似文献
995.
Tomoki Matsuda Makoto Fujikawa Mitsuru Haruki Xiao-Feng Tang Satoshi Ezaki Tadayuki Imanaka Masaaki Morikawa Shigenori Kanaya 《Extremophiles : life under extreme conditions》2001,5(3):177-182
Interactions of TBP-interacting protein (TIP26), TBP, and TFB from a hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 with TATA-DNA were examined by electrophoretic mobility shift assay. Tk-TFB formed a ternary complex with Tk-TBP and TATA-DNA. Tk-TIP26 did not inhibit the formation of this ternary complex, but interacted with it to form a TIP26/TFB/TBP/DNA quaternary complex. This interaction is rather weak, and a large excess of Tk-TIP26 over Tk-TBP is required to fully convert the TFB/TBP/DNA ternary complex to the quaternary complex. However, determination of the concentration of Tk-TIP26 and Tk-TBP in KOD1 cells by Western blotting analysis indicated that the concentration of Tk-TIP26 is approximately ten times that of Tk-TBP, suggesting that the quaternary complex might also form in vivo. 相似文献
996.
997.
Kazuhiro Usui Yoji Sasahara Ryushi Tazawa Koichi Hagiwara Satoshi Tsukada Toshio Miyawaki Shigeru Tsuchiya Toshihiro Nukiwa 《Respiratory research》2001,2(3):188-5
Background
X-linked agammaglobulinemia (XLA) is a humoral immunodeficiency caused by disruption of the Bruton's tyrosine kinase (BTK) gene. Typical XLA patients suffer recurrent and severe bacterial infections in childhood. 相似文献998.
Site-specific modification of functional groups in genomic hepatitis delta virus (HDV) ribozyme. 总被引:3,自引:0,他引:3
Fumiko Nishikawa Miho Shirai Satoshi Nishikawa 《European journal of biochemistry》2002,269(23):5792-5803
Human hepatitis delta (HDV) ribozyme is one of small ribozymes, such as hammerhead and hairpin ribozymes, etc. Its secondary structure shows pseudoknot structure composed of four stems (I to IV) and three single-stranded regions (SSrA, -B and -C). The 3D structure of 3'-cleaved product of genomic HDV ribozyme provided extensive information about tertiary hydrogen bonding interactions between nucleotide bases, phosphate oxygens and 2'OHs including new stem structure P1.1. To analyze the role of these hydrogen bond networks in the catalytic reaction, site-specific atomic-level modifications (such as deoxynucleotides, deoxyribosyl-2-aminopurine, deoxyribosylpurine, 7-deaza-ribonucleotide and inosine) were incorporated in the smallest trans-acting HDV ribozyme (47-mer). Kinetic analysis of these ribozyme variants demonstrated the importance of the two W-C base pairs of P1.1 for cleavage; in addition, the results suggest that all hydrogen bond interactions detected in the crystal structure involving 2'-OH and N7 atoms are present in the active ribozyme structure. In most of the variants, the relative reduction in kobs caused by substitution of the 2'-OH group correlated with the number of hydrogen bonds affected by the substitution. However G74 and C75 may have more than one hydrogen bond involving the 2'-OH in both the trans- and cis-acting HDV ribozyme. Moreover, in variants in which N7 was deleted, kobs was reduced 5- to 15-fold, it may suggest that N7 assists in coordinating Mg2+ ions or water molecules which bind with weak affinity in the active structure. 相似文献
999.
We found that the gradient of a host-specific attractant, cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone) isolated from the roots of spinach triggered encystment followed by germination of zoospores of Aphanomyces cochlioidesat a concentration less than micromolar order. This compound did not affect the growth and reproduction of this phytopathogen up to 10–6 M concentration in the culture medium. We also observed that mastoparan, an activator of heterotrimeric G-protein could inhibit the motility of zoospores and then strikingly effect encystment followed by 60–80% germination of cysts. Concomitant application of cochliophilin A and mastoparan showed stronger encystment followed by 100% germination of cysts. In addition, we have observed that chemicals interfering with phospholipase C activity (neomycin) and Ca2+ influx/release (EGTA and loperamide) suppress cochliophilin A or mastoparan induced encystment and germination. These results suggest that G-protein mediated signal transduction mechanism may be involved in the differentiation of the A. cochlioides zoospores. This is the first report on the differentiation of oomycete zoospores initiated by a host-specific plant signal or a G-protein activator. 相似文献
1000.
Ammonia-oxidizing bacteria on root biofilms and their possible contribution to N use efficiency of different rice cultivars 总被引:12,自引:0,他引:12
Briones Aurelio M. Okabe Satoshi Umemiya Yoshiaki Ramsing Niels-Birger Reichardt Wolfgang Okuyama Hidetoshi 《Plant and Soil》2003,250(2):335-348
Ammonia-oxidizing bacteria (AOB) populations were studied on the root surface of different rice cultivars by PCR coupled with denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH). PCR-DGGE of the ammonium monooxygenase gene (amoA) showed a generally greater diversity on root samples compared to rhizosphere and unplanted soil. Sequences affiliated with Nitrosomonas spp. tended to be associated with modern rice hybrid lines. Root-associated AOB observed by FISH were found within a discrete biofilm coating the root surface. Although the total abundance of AOB on root biofilms of different rice cultivars did not differ significantly, there were marked contrasts in their population structure, indicating selection of Nitrosomonas spp. on roots of a hybrid cultivar. Observations by FISH on the total bacterial community also suggested that different rice cultivars support different bacterial populations even under identical environmental conditions. The presence of active AOB in the root environment predicts that a significant proportion of the N taken up by certain rice cultivars is in the form of NO3
–-N produced by the AOB. Measurement of plant growth of hydroponically grown plants showed a stronger response of hybrid cultivars to the co-provision of NH4
+ and NO3
–. In soil-grown plants, N use efficiency in the hybrid was improved during ammonium fertilization compared to nitrate fertilization. Since ammonium-fertilized plants actually receive a mixture of NH4
+ and NO3
– with ratios depending on root-associated nitrification activity, these results support the advantage of co-provision of ammonium and nitrate for the hybrid cultivar. 相似文献