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M Yoshida

Publications and source records attributed to M Yoshida.

At least 1,081 records · Page 60Linked to original sources
PubMed1996

A novel factor required for the assembly of the DnaK and DnaJ chaperones of Thermus thermophilus.

We previously reported the isolation of T.DnaK.DnaJ chaperone complex from Thermus thermophilus. Here, we show that a novel factor is necessary for the assembly of T.DnaK and T.DnaJ into the complex. A dnaK gene cluster of T. thermophilus contained five genes, dnaK-grpE-dnaJ-orf4-clpB. Interestingly, T.DnaJ lacks the whole "cysteine-rich region" that has been postulated to be necessary to bind unfolded proteins. The orf4 gene encodes a novel 78-amino acid protein. Curiously, T.DnaK and T.DnaJ expressed in Escherichia coli did not form the complex. Careful reexamination of the T.DnaK.DnaJ complex revealed the presence of a small protein in the complex, which turned out to be a product of orf4. As expected, expression of three genes, dnaK-dnaJ-orf4, resulted in production of a T.DnaK.DnaJ complex in E. coli that was indistinguishable from the authentic complex in its ability to interact with nucleotide and denatured protein. The product of orf4 was also required for in vitro reconstitution of the complex and named T.DafA (T.DnaK.DnaJ assembly factor A). The complex comprises three copies each of T.DnaK, T.DnaJ, and T.DafA. Even though a definite homolog of T.DafA has not been found in the data base, this finding raises a possibility that interaction between DnaK and DnaJ chaperones in other organisms is also mediated by a small protein yet unnoticed.

Amino Acid Sequence↗
PubMed1996

Characterization of a potential catalytic residue, Asp-133, in the high affinity ATP-binding site of Escherichia coli SecA, translocation ATPase.

The high affinity ATP-binding site of SecA is located in its amino-terminal domain possessing amino acid sequences, the Walker A (GXXXXGKT) and B (ZZZZD) motifs, that are characteristic of a major class of nucleotide-binding sites (Walker, J. E., Saraste, M., Runswick, M. J., and Gay, N. J. (1982) EMBO J. 1, 945-951). Recently, we proposed that proteins possessing a typical set of Walker A and B motifs contain a conserved Glu or Asp between the two motifs. This Glu or Asp acts as a "catalytic residue" that activates a water molecule for an in-line attack on the gamma-phosphate of ATP (Amano, T., Yoshida, M., Matsuo, Y., and Nishikawa, K.(1995) FEBS Lett. 359, 1-5). In the present study, the aspartate residue at position 133 in Escherichia coli SecA, which could be the "catalytic residue," was mutated to an asparagine. The mutant SecA (SecA D133N) protein was expressed in E. coli CK4706, encoding a duplication of the secA gene, and purified to homogeneity. The in vitro protein translocation activity and membrane vesicle stimulated ATPase activity of SecA D133N were drastically reduced. Proteolytic studies indicated that the conformational changes of the mutant SecA occurring on interaction with ATP, presecretory proteins, phospholipids, and membrane vesicles, were similar to those of wild-type SecA. The mutant SecA allowed the signal peptide cleavage of proOmpA during translocation, indicating that the mutant retains the ability to bind ATP to perform the initial step of the translocation reaction. These data indicate that the carboxyl group of Asp-133 plays a role as a catalytic carboxylate, which activates a water molecule to attack gamma-phosphate of ATP, and the mutant lacking this residue cannot perform the total translocation but can still perform the initial step of the protein translocation.

Adenosine Triphosphatases↗
PubMed1996

Angiotensin II-induced renal responses in anesthetized rabbits: effects of N omega-nitro-L-arginine methyl ester and losartan.

Intrarenal arterial infusion of angiotensin II (4 ng/kg/min) reduced renal blood flow, glomerular filtration rate and urinary Na+ excretion (UNaV) without affecting fractional Na+ excretion (FENa) in anesthetized rabbits. Losartan (10 micrograms/kg/min) abolished these angiotensin II-induced renal responses. The renal blood flow, glomerular filtration rate and UNaV responses were potentiated during intrarenal arterial infusion of N omega-nitro-L-arginine methyl ester (L-NAME, 10 micrograms/kg/min). A high dose of L-NAME (50 micrograms/kg/min) also potentiated the renal blood flow and UNaV responses but not the glomerular filtration rate response. Angiotensin II reduced FENa during L-NAME infusion at either dose. In L-NAME-pretreated rabbits, losartan abolished the angiotensin II-induced renal blood flow and glomerular filtration rate responses, but the reduction in FENa still remained. The present study suggests that in the rabbit kidney (1) nitric oxide attenuates the angiotensin II-induced (angiotensin AT1 receptor-mediated) vasoconstriction and (2) angiotensin II can evoke losartan-resistant tubular Na+ reabsorption, but the tubular action is concealed by nitric oxide.

Angiotensin II↗
PubMed1996

Rapid and high yield induction of endometrial adenocarcinomas in CD-1 mice by a single intrauterine administration of N-ethyl-N-nitrosourea combined with chronic 17 beta-estradiol treatment.

Induction of uterine endometrial adenocarcinomas in mice by N-ethyl-N-nitrosourea (ENU) and 17 beta-estradiol (E2) was examined. Illumination-induced persistent estrous CD-1 mice were divided into three groups at 10 weeks of age. Group 1 was given a single intra-uterine administration of polyethylene glycol (PEG) 1 week later, while Groups 2 and 3 received ENU (12.5 mg/kg), dissolved in PEG, in the same manner. Group 3 mice were also implanted with E2 pellets s.c. 1 week previously, and thereafter the pellets were renewed every 8 weeks throughout the experiment. At the termination (week 15 after the ENU treatment), all surviving mice were killed and the development of uterine proliferative lesions was assessed. All groups demonstrated endometrial hyperplasias, the severity being greatest in the ENU plus E2-treated animals (Group 3). The incidence of adenocarcinomas in Group 3 (20/29, 69%) was significantly higher than in Group 1 (0/25, 0%) or 2 (0/29, 0%). At 10 weeks after the ENU-treatment, serum E2 and progesterone concentrations in Group 3 were significantly higher and lower, respectively, than those in Groups 1 and 2. Consequently, the E2/progesterone (E2:P) ratio in Group 3 was significantly increased. These results indicate that a continuing high level of serum E2 and low level of progesterone are important for endometrial adenocarcinoma development in mice, with an increased E2:P ratio acting as a promoter for development of the endometrial lesions initiated by ENU treatment.

Adenocarcinoma↗
PubMed1996

N (epsilon)-(carboxymethyl)lysine protein adduct is a major immunological epitope in proteins modified with advanced glycation end products of the Maillard reaction.

Long-term incubation of proteins with glucose leads to the formation of advanced glycation end products (AGE). Recent immunological studies have suggested the potential role of AGE in atherosclerosis, aging, and diabetic complications. We previously prepared a monoclonal (6D12) as well as a polyclonal anti-AGE antibody and proposed the presence of a common AGE structure(s) that may act as a major immunochemical epitope [Horiuchi, S., Araki, N., & Morino, Y. (1991) J. Biol. Chem. 266, 7329-7332]. The purpose of the present study was to determine the major epitope. Amino acid analysis of AGE-proteins indicated that N(epsilon)-(carboxymethyl)lysine (CML) was a major modified lysine residue. Immunologic studies demonstrated the positive reaction of 6D12 not only to all CML-modified proteins tested, but also to BSA modified with several aldehydes known to generate a CML-protein adduct, and a linear correlation between the CML contents of CML-BSA and their immunoreactivity to 6D12 up to approximately 8 mol/mol of protein. Further experiments with CML analogs revealed that the epitope of 6D12 is a CML-protein adduct with an important carbonyl group. In contrast to 6D12, our polyclonal anti-AGE antibody showed a significant but much weaker immunoreactivity to CML-BSA, suggesting that the polyclonal antibody contains two populations, one reactive to CML (CML-PA) and the other unreactive to CML (Non-CML-PA). Non-CML-PA separated from CML-PA by CML-BSA affinity chromatography did not react with all CML-modified preparations, but retained its property to react commonly with AGE preparations obtained from proteins, lysine derivatives, and monoaminocarboxylic acids. Therefore, it is clear that a CML-protein adduct is a major immunological epitope in AGE structures, but there still exist other major epitope(s) expressed commonly in AGE-proteins.

Animals↗
PubMed1996

A method for detection of HHV-6 antigens and its use for evaluating antiviral drugs.

A simple and reproducible method for detection of human herpesvirus 6 (HHV-6) antigens was developed using a dot blot assay in order to assess virus titer and to evaluate the effect of antiviral drugs against HHV-6. The titer of virus stocks obtained by the dot blot assay was the same as that determined by an immunofluorescence assay (IFA). This method was then applied to evaluate the effect of several antiviral drugs against HHV-6, including phosphonoformic acid (PFA), 9-(2-hydroxyethoxymethyl)guanine (ACV), 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine (DHPG) and (S)-1-[(3-hydroxy-2-phosphonylmethoxy)propyl]cytosine [(S)-HPMPC]. The end-point concentrations (EPC, which was determined visually) of DHPG and (S)-HPMPC were approximately 1 microgram/ml. These drugs were more effective than the others which had EPCs of approximately 16 micrograms/ml each. The EPC values of four drugs were almost similar to EC90 values determined by measuring density of each dot blot. Thus, the EPC values can be utilized to determine the efficacy of these drugs in the inhibition of HHV-6 replication. The block in virus replication was not due to toxic effect of these drugs on cord blood mononuclear cells (CBMCs). These results suggest that a dot blot method which detects HHV-6 antigens can be useful for titrating virus yield and evaluating antiviral drugs against HHV-6 replication.

Antigens, Viral↗
PubMed1996

Magnesium(II) is a crucial constituent of the blood coagulation cascade. Potentiation of coagulant activities of factor IX by Mg2+ ions.

We recently showed that not only Ca2+ ions but also Mg2+ ions play a crucial role in stabilizing the native conformation of coagulation factor IX. We here report that Mg2+ ions at physiological concentrations greatly augment the biological activities of factor IX. In clotting assays with dialyzed plasma, addition of Mg2+ ions enhanced the apparent coagulant activity of factor IXa, while that of factor Xa was scarcely affected. Activation of factor X by factor IXa in the presence of factor VIIIa, phospholipids, and Ca2+ ions was accelerated by Mg2+ ions. It appeared that the cation increased the affinity between factor IXa and factor VIIIa, thereby increasing the apparent catalytic efficacy of the enzyme. We also evaluated the effect of Mg2+ ions in the coagulation pathway initiated by tissue factor and found that activation of factor IX by factor VIIa*tissue factor was accelerated by the cation. Consequently, clotting of normal plasma induced by factor VIIa*tissue factor was shortened by the cation, while no such effect was observed in plasma deficient in factor IX or VIII. These results indicate that the previously unrecognized plasma component, Mg2+ ions, plays crucial roles in blood coagulation and, moreover, that contributions of factors IX and VIII in the coagulation cascade have been seriously underestimated in previous investigations.

Blood Coagulation↗
PubMed1996

Antitumor activity of daphnane-type diterpene gnidimacrin isolated from Stellera chamaejasme L.

The daphnane-type diterpene gnidimacrin, isolated from the root of the Chinese plant, Stellera chamaejasme L., was found to strongly inhibit cell growth of human leukemias, stomach cancers and non-small cell lung cancers in vitro at concentrations of 10(-9) to 10(-10) M. On the other hand, even at 10(-6) to 10(-5) M, the small cell lung cancer cell line H69 and the hepatoma cell line HLE were refractory to gnidimacrin. The agent showed significant antitumor activity against murine leukemias and solid tumors in an in vivo system. In K562, a sensitive human leukemia cell line, gnidimacrin induced blebbing of the cell surface, which was completely inhibited by staurosporine at concentrations above 10(-8) M, and arrested the cell cycle transiently to G2 and finally the G1 phase at growth-inhibitory concentrations. It inhibited phorbol-12,13-dibutyrate(PDBu) binding to K562 cells and directly stimulated protein kinase C (PKC) activity in the cells in a dose-dependent manner (3-100 nM). Although activation of PKC isolated from refractory H69 cells was observed only with 100 nM gnidimacrin, the degree of activation was lower than that produced by 3 nM in K562 cells. Our results suggest that gnidimacrin acts as a PKC activator for tumor cells and that this mechanism may be responsible for its antitumor activity.

Animals↗
PubMed1996

HTLV-1 Tax protein interacts with cyclin-dependent kinase inhibitor p16INK4A and counteracts its inhibitory activity towards CDK4.

Tax, a regulatory protein of human T-cell leukemia virus type 1 (HTLV-1), is an oncoprotein which immortalizes human T cells and induces tumors in transgenic mice. These effects may be due to its interaction with cellular proteins, consisting of several transcription factors including CREB, NF-kappa B and SRF, and the transcriptional inhibitor, I kappa B. Here, we found that Tax binds to a cyclin-dependent kinase inhibitor, p16INK4A, which has ankyrin motifs similar to I kappa B. p16INK4A binds to the cyclin-dependent kinases, CDK4 and CDK6, and inhibits their activity, resulting in suppression of G1 phase progression. The binding of Tax to p16INK4a induced a reduction in the p16INK4A-CDK4 complex, with subsequent activation of CDK4 kinase. Tax also suppressed p16INK4A-mediated inhibition of U2OS cell growth. The p16INK4A gene was frequently deleted in many T-cell lines, but not in HTLV-1-infected T-cell lines. Taking these findings together, the functional inactivation of p16INK4A by Tax through protein-protein interaction is suggested to contribute to cellular immortalization and transformation induced by HTLV-1 infection.

Animals↗
PubMed1996

An attempt to convert noncatalytic nucleotide binding site of F1-ATPase to the catalytic site: hydrolysis of tethered ATP by mutated alpha subunits in the enzyme.

The alpha and beta subunits of F1-ATPase are homologous in primary structure and have similar folding topologies. The position of the essential Glu residue in the catalytic sites which reside in the beta subunits is occupied by a Gln residue in the noncatalytic nucleotide binding sites which reside in the alpha subunits. To test if an exchange of catalytic and noncatalytic binding sites is possible, we have replaced the Gln-Lys sequence in the noncatalytic binding site of the alpha subunit with Glu-Arg and, reciprocally, the Glu in the catalytic site of the beta subunit with Gln. The resultant mutant alpha3beta3gamma complex lost steady-state ATPase activity. However, HPLC analysis of tryptic digests of the mutant alpha3beta3gamma complex which had been photolabeled with 2-N3-[8-3H]ATP revealed that ATP tethered to the noncatalytic binding side was hydrolyzed, indicating that a primitive catalytic ability was generated at the alpha subunit by the introduced Glu.

Adenosine Triphosphate↗
PubMed1996

ATP-sensitive K+ channel openers block sulpiride-induced dopamine release in the rat striatum.

In vivo brain microdialysis was used to investigate the role of ATP-sensitive K+ (KATP) channel openers in dopamine release regulated by dopamine autoreceptors in the rat striatum. Local infusion of two KATP channel openers, nicorandil (10(-5)-10(-3) M) and cromakalim (10(-5)-10(-3) M), into the striatum thorough the dialysis membrane produced dose-dependent decreases in extracellular concentrations of dopamine. Local application of the dopamine D2 receptor antagonist, (-)-sulpiride (10(-5) M), produced significant increases in extracellular concentrations of dopamine. Both nicrorandil (10(-5) M) and cromakalim (10(-4) M) blocked significantly (-)-sulpiride (10(-5) M)-induced increases in dopamine levels in the striatum. These results suggest that activation of KATP channels in the striatum causes decreases in endogenous dopamine release in vivo. Furthermore, the sulpiride-induced increases in dopamine levels caused by blocking the tonic activation of dopamine autoreceptors were inhibited by activation of KATP channel. These data indicate that KATP channels may be present in nigrostriatal dopaminergic terminals and that striatal dopamine autoreceptors inhibit dopamine release tonically by activation of KATP channels.

Adenosine Triphosphate↗
PubMed1996

Tob, a novel protein that interacts with p185erbB2, is associated with anti-proliferative activity.

We have molecularly cloned a cDNA for a novel protein termed Tob (Transducer of ErbB-2) that interacts with the c-erbB-2 gene product p185erbB2. Nucleotide sequencing reveals that the Tob protein is a 45 kDa protein that does not contain either SH2 (Src Homology 2) or SH3 domain but is homologous to the previously characterized anti-proliferative gene product BTG-1 at its amino-terminal half. The carboxyl-terminal half of Tob is characterized by the presence of a sequence rich in proline and glutamine and shows no homology to known proteins. Like BTG-1, exogenously expressed Tob is able to suppress growth of NIH3T3 cells, but the growth suppression is hampered by the presence of kinase-active p185erbB2. By using the GST-Tob protein that contains either full length or amino-terminal half of Tob, we show that the carboxyl-terminal half of Tob is relevant to its interaction with p185erbB2. Furthermore, we could co-immunoprecipitate the Tob protein with anti-ErbB-2 antibody, and reciprocally the p185erbB2 with anti-Tob antibodies. These data suggest that p185erbB2 negatively regulates the Tob-mediated anti-proliferative pathway through its interaction with Tob, resulting possibly in growth stimulation by p185erbB2. Finally, expression of the Tob mRNA is observed in various cell types and is not correlated with expression of c-erbB-2, suggesting that other receptor-type protein-tyrosine kinases are also involved in the Tob-mediated regulation of cell growth.

3T3 Cells↗
PubMed1996

Structural asymmetry of F1-ATPase caused by the gamma subunit generates a high affinity nucleotide binding site.

The alpha 3 beta 3 gamma and alpha 3 beta 3 complexes of F1-ATPase from a thermophilic Bacillus PS3 were compared in terms of interaction with trinitrophenyl analogs of ATP and ADP (TNP-ATP and TNP-ADP) that differed from ATP and ADP and did not destabilize the alpha 3 beta 3 complex. The results of equilibrium dialysis show that the alpha 3 beta 3 gamma complex has a high affinity nucleotide binding site and several low affinity sites, whereas the alpha 3 beta 2 complex has only low affinity sites. This is also supported from analysis of spectral change induced by TNP-ADP, which in addition indicates that this high affinity site is located on the beta subunit. Single-site hydrolysis of substoichiometric amounts of TNP-ATP by the alpha 3 beta 3 gamma complex is accelerated by the chase addition of excess ATP, whereas that by the alpha 3 beta 3 complex is not. We further examined the complexes containing mutant beta subunits (Y341L, Y341A, and Y341C). Surprisingly, in spite of very weak affinity of the isolated mutant beta subunits to nucleotides (Odaka, M., Kaibara, C., Amano, T., Matsui, T., Muneyuki, E., Ogasawara, K, Yutani, K., and Yoshida, M. (1994) J. Biochem. (Tokyo) 115, 789-796), a high affinity TNP-ADP binding site is generated on the beta subunit in the mutant alpha 3 beta 3 gamma complexes where single-site TNP-ATP hydrolysis can occur. ATP concentrations required for the chase acceleration of the mutant complexes are higher than that of the wild-type complex. The mutant alpha 3 beta 3 complexes, on the contrary, catalyze single-site hydrolysis of TNP-ATP rather slowly, and there is no chase acceleration. Thus, the gamma subunit is responsible for the generation of a high affinity nucleotide binding site on the beta subunit in F1-ATPase where cooperative catalysis can proceed.

Adenosine Diphosphate↗
PubMed1996

The three human syntrophin genes are expressed in diverse tissues, have distinct chromosomal locations, and each bind to dystrophin and its relatives.

The syntrophins are a biochemically heterogeneous group of 58-kDa intracellular membrane-associated dystrophin-binding proteins. We have cloned and characterized human acidic (alpha 1-) syntrophin and a second isoform of human basic (beta 2-) syntrophin. Comparison of the deduced amino acid structure of the three human isoforms of syntrophin (together with the previously reported human beta 1-syntrophin) demonstrates their overall similarity. The deduced amino acid sequences of human alpha 1- and beta 2-syntrophin are nearly identical to their homologues in mouse, suggesting a strong functional conservation among the individual isoforms, Much like beta 1-syntrophin, human beta 2-syntrophin has multiple transcript classes and is expressed widely, although in a distinct pattern of relative abundance. In contrast, human alpha 1-syntrophin is most abundant in heart and skeletal muscle, and less so in other tissues. Somatic cell hybrids and fluorescent in situ hybridization were both used to determine their chromosomal locations: beta 2-syntrophin to chromosome 16q22-23 and alpha 1-syntrophin to chromosome 20q11.2. Finally, we used in vitro translated proteins in an immunoprecipitation assay to show that, like beta 1-syntrophin, both beta 2- and alpha 1-syntrophin interact with peptides encoding the syntrophin-binding region of dystrophin, utrophin/dystrophin related protein, and the Torpedo 87K protein.

Adult↗
PubMed1996

High plasma level of plasmin-alpha 2-plasmin inhibitor complex is predictor of poor prognosis in patients with lung cancer.

The occurrence of thrombotic complications is commonly associated with poor prognosis in patients with malignancy. However, the prognostic significance of the subclinical activation of the clotting system, frequently observed in cancer patients, is unknown. The purpose of the present study was to evaluate the value of the pre-thrombotic state for predicting survival of lung cancer patients. This investigation comprised 70 lung cancer patients without clinical or laboratory diagnosis of intravascular coagulation. There were 49 cases with non-small and 21 with small cell carcinomas. Samples taken in controls were available for comparison. The clotting system was assessed measuring thrombin-antithrombin III complex (TAT) and plasmin-alpha 2-plasmin inhibitor complex (PAP). The independent value of these clotting markers to predict survival was evaluated in relation with previously well-established prognostic factors for lung cancer patients. Plasma concentration of each parameter was significantly higher in cancer patients as compared to that of controls. The plasma level of PAP was a predictor of survival independently from the stage of disease, sex, age, histological type, performance status, tumor size and the presence of distant metastasis. Discriminant analysis of PAP plasma concentration identified 2 groups with significant difference in survival rate in all patients, cases in advanced stages of disease and in those with small and non-small cell lung cancer. The results of the present study showed prognostic significance of the subclinical activation of the clotting system, particularly of the fibrinolytic pathway, in lung cancer. Newly developed markers of fibrinolysis might be potentially applicable for predicting outcome in malignancy.

Adult↗
PubMed1996

High dose of intravenous antithrombin III without heparin in the treatment of disseminated intravascular coagulation and organ failure in four children.

In several animal experiments, high doses of antithrombin III concentrates have shown beneficial effects on mortality and reversal of coagulation abnormalities which had resulted from disseminated intravascular coagulation. Other experiments have suggested that antithrombin III infusion without heparin is effective in the treatment of organ failure. We clinically treated children suffering disseminated intravascular coagulation only with antithrombin concentrate. Four patients suffering disseminated intravascular coagulation with organ failure were selected. We started antithrombin III concentrate infusion as soon as the diagnosis was established. The dosage of antithrombin III was 120-250 units/kg/day for 2 or 3 days. Heparin was not used. All 4 patients recovered completely and quickly without any complications within 14 days. We suggest that the high-dose antithrombin III infusion without heparin is an effective and safe therapy for disseminated intravascular coagulation with organ failure.

Antithrombin III↗
PubMed1996

Comparison of the association with eczema herpeticum in the two predominant genotypes of herpes simplex virus type 1.

Eczema herpeticum, sometimes called Kaposi's varicelliform eruption, is usually caused by a disseminated herpes simplex virus infection in a patient whose underlying skin disease in atopic dermatitis. Herpes simplex virus type 1 (HSV-1), a widespread infectious agent in human populations, is the etiologic agent of eczema herpeticum. Analyses of restriction fragment length polymorphism (RFLP) of HSV-1 strains isolated in Japan, using restriction endonucleases, revealed the presence of two predominant genotypes of F1 and F35. The number of HSV-1 strains of F1 genotype was over twice that of the F35 genotype, and the nucleotide change between F1 and F35 was estimated to be 1.5%. The question of whether the genomic difference between two predominant genotypes could influence clinical manifestations remained to be addressed. On the basis of RFLP, we determined genotypes of HSV-1 strains isolated from the patients in Japan, including those with eczema herpeticum. Two of four HSV-1 strains of F35 genotype were from patients with eczema herpeticum, whereas none of 12 HSV-1 strains of F1 genotype was from those with eczema herpeticum. Thus, the F35 genotype seemed to be associated more frequently with eczema herpeticum than the F1 genotype.

Animals↗