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T Miki

Publications and source records attributed to T Miki.

At least 379 records · Page 21Linked to original sources
PubMed1996

A 570-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 28.0-40.1 min region on the linkage map.

The 569,750 base pair sequence corresponding to the 28.0-40.1 min region on the genetic map of Escherichia coli K-12 (W3110) was determined. This region includes the replication terminus region and contained at least 549 potential open reading frames. Among them, 160 (29%) were previously reported, 174 (32%) were homologous to other known genes, 102 (18%) were identical or similar to hypothetical genes registered in databases, and the remaining 113 (21%) did not show a significant similarity to any other gene. Of interest was the finding of a large number of genes and gene clusters in and near the replication termination region which had been thought to be genetically silent. Those included a cluster of genes for fatty acid beta-oxidation, the third copy of the pot (spermidine/putrescine transport system) gene cluster, the second dpp (dipeptide transport system) operon, the second dsm (anaerobic dimethyl sulfoxide reductase) operon, a cluster of fim (fimbrial) genes and a DNA helicase-like gene with a high molecular weight. In addition, we found the dnaC- and dnaT-like genes in the cryptic prophage, Rac, and a number of genes originated probably from plasmids.

Chromosome Mapping↗
PubMed1996

A 460-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 40.1-50.0 min region on the linkage map.

The 465,813 base pair sequence corresponding to the 40.1-50.0 min region on the genetic map of Escherichia coli K-12 (W3110) was determined. Analysis of the sequence revealed that this region contained at least 466 potential open reading frames, of which 187 (40%) were previously reported, 105 (23%) were homologous to other known genes, 103 (22%) were identical or similar to hypothetical genes registered in databases, and the remaining 71 (15%) did not show a significant similarity to any other gene. At the 45.2-46.0 min region, we found a very large cluster of about 30 genes, whose functions are involved in the biosynthesis of polysaccharides as the components of outer membranes. In addition, we identified a new asn-tRNA gene, designated asnW, between the asnT and asnU genes and a new lysogenic phage attachment site as the cis-element.

Attachment Sites, Microbiological↗
PubMed1996

Fas/APO-1-mediated apoptosis of human renal cell carcinoma.

We have investigated the Fas-mediated apoptosis of cultured human renal cell carcinoma OUR-10. OUR-10 cells express Fas antigen on their cell surface and showed apoptotic cell death by stimulation with anti-Fas agonistic antibody. Cell proliferation of OUR-10 was reduced to 62% by the addition of anti-Fas antibody. The cytotoxic effect of anti-Fas antibody on OUR-10 was augmented by the pretreatment of these cells with interferon-gamma, not with interferon-alpha or with interleukin-2. Flow cytometry demonstrated that preculture of Our-10 cells with interferon-gamma increased the cell surface Fas antigen. Immunohistochemical analysis of resected tissues from the patients with renal cancer revealed stronger expression of Fas antigen on the surface of cancer cells than that of normal cells. These data suggest that Fas may be one of the possible targets for a novel approach to human kidney cancer, and the efficiency of this Fas-mediated treatment for kidney cancer could be augmented by the treatment with interferon-gamma.

Apoptosis↗
PubMed1996

Increase in synthesis and stability of sigma 32 on treatment with inhibitors of DNA gyrase in Escherichia coli.

We report here that in Escherichia coli, the anti-bacterial agent nalidixic acid induces transient stabilization and increased synthesis of sigma 32, accompanied by the induction of heat shock proteins (Dnak and GroEL proteins). The induction of heat shock proteins, increased synthesis of sigma 32, and stabilization of sigma 32 observed on treatment of wild-type cells with nalidixic acid were not observed in a nalA26 mutant, a strain that is resistant to nalidixic acid as the result of a mutation in the gyrA gene. Not only oxolinic acid, but also novobiocin, whose targets are the A and B subunits of DNA gyrase, respectively, also induced stabilization and increased synthesis of sigma 32. Thus, inhibition of the activity of DNA gyrase may cause stabilization and increased synthesis of sigma 32, resulting in turn in induction of heat shock proteins.

Anti-Infective Agents↗
PubMed1996

Captopril potentiates the myocardial infarct size-limiting effect of ischemic preconditioning through bradykinin B2 receptor activation.

OBJECTIVES: To investigate the role of kinin in preconditioning against infarction, the present study assessed the effect of captopril, a kininase II inhibitor, on preconditioning and arterial plasma kinin levels. BACKGROUND: Recent studies suggest a possible contribution of kinin to preconditioning against infarction. However, its role and the site of kinin production remain uncharacterized. METHODS: Six groups of rabbits (n = 6 to 13) underwent 30-min coronary occlusion and 3-h reperfusion. The infarct size and area at risk were determined by tetrazolium staining and fluorescent particles, respectively. Arterial blood was sampled under baseline conditions, before the 30-min ischemia and after reperfusion for radioimmunoassay of the kinin level. RESULTS: Infarct size expressed as a percentage of area at risk (%IS/AR) was 42.9 +/- 2.9% (mean +/- SEM) in the control group, 34.5 +/- 3.3% in the group preconditioned with 2 min of ischemia/5 min of reperfusion and 41.7 +/- 5.1% in the group given captopril (1 mg/kg body weight) alone before the 30-min ischemia. These %IS/AR values were not significantly different between the three groups. However, a combination of captopril and subsequent preconditioning with 2 min of ischemia markedly limited %IS/AR to 21.2 +/- 2.4%. This potentiation of 2 min of preconditioning by captopril was not observed when 2 micrograms/kg body weight of Hoe 140, a specific bradykinin B2 receptor antagonist, was administered before preconditioning (%IS/AR = 41.2 +/- 5.7%), whereas Hoe 140 alone did not modify infarct size (%IS/AR = 38.5 +/- 5.1%). Arterial plasma kinin levels were comparable between the control rabbits, the group given captopril alone and the group that received captopril plus 2 min of preconditioning at baseline (3.8 +/- 1.0, 6.3 +/- 1.9 and 5.2 +/- 1.7 pg/ml, respectively), and there was no significant change in kinin levels after the captopril injection or the combination of captopril plus 2 min of preconditioning. CONCLUSIONS: The present results indicate that captopril is capable of potentiating preconditioning without increasing the arterial kinin level and that the beneficial effect of captopril can be inhibited by Hoe 140. These findings support the hypothesis that kinin produced locally in the heart during preconditioning may contribute to the cardioprotective mechanism through bradykinin receptor activation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

DnaK heat shock protein of Escherichia coli maintains the negative supercoiling of DNA against thermal stress.

Plasmid DNA in exponentially growing Escherichia coli immediately relaxes after heat shock, and the relaxed state of DNA rapidly reverts to the original state with exposure to conditions of heat shock. We have now obtained genetic and biochemical evidence indicating that DnaK heat shock protein of E. coli, a prokaryotic homologue of hsp70, is involved in this re-supercoiling of DNA. As re-supercoiling of DNA did not occur in an rpoH amber mutant, it seems likely that heat shock proteins are required for this reaction. Plasmid DNA in a dnaK deletion mutant relaxed excessively after temperature shift-up, and the re-supercoiling of DNA was not observed. DNAs incubated with a crude cell extract prepared from the dnaK mutant were more relaxed than seen with the extract from its isogenic wild-type strain, and the addition of purified DnaK protein to the mutant extract led to an increase in the negative supercoiling of DNA. Moreover, reaction products of purified DNA gyrase more negatively supercoiled in the presence of DnaK protein. Based on these results, we propose that DnaK protein plays a role in maintaining the negative supercoiling of DNA against thermal stress.

Cell Extracts↗
PubMed1996

The BCL6 gene is predominantly expressed in keratinocytes at their terminal differentiation stage.

We analyzed the expression of the BCL6 gene in mouse tissues by in situ hybridization. The expression was strong in the upper layer but undetectable in the basal layer of epidermis from adult mice. When human keratinocytes were cultured with a high concentration of calcium ion, these cells stopped their proliferation and differentiated to their terminal stage. In these keratinocytes, BCL6 expression was induced after stimulation and progressively up-regulated. The kinetics was very similar to that of a cyclin dependent kinase inhibitor p21sdil/cip1/WAF1 in these cells. These results suggest that BCL6 plays a role in keratinocytes at terminal differentiation stage.

Animals↗
PubMed1996

Signaling from the small GTP-binding proteins Rac1 and Cdc42 to the c-Jun N-terminal kinase/stress-activated protein kinase pathway. A role for mixed lineage kinase 3/protein-tyrosine kinase 1, a novel member of the mixed lineage kinase family.

Certain small GTP-binding proteins control the enzymatic activity of a family of closely related serine-threonine kinases known as mitogen-activated protein kinases (MAPKs). In turn, these MAPKs, such as p44(mapk) and p42(mapk), referred to herein as MAPKs, and stress-activated protein kinases, also termed c-Jun N-terminal kinases (JNKs), phosphorylate and regulate the activity of key molecules that ultimately control the expression of genes essential for many cellular processes. Whereas Ras controls the activation of MAPK, we and others have recently observed that two members of the Rho family of small GTP-binding proteins, Rac1 and Cdc42, regulate the activity of JNKs. The identity of molecules communicating Rac1 and Cdc42 to JNK is still poorly understood. It has been suggested that Pak1 is the most upstream kinase connecting these GTPases to JNK; however, we have observed that coexpression of Pak1 with activated forms of Cdc42 or Rac1 diminishes rather than enhances JNK activation. This prompted us to explore the possibility that kinases other than Pak might participate in signaling from GTP-binding proteins to JNK. In this regard, a computer-assisted search for proteins containing areas of homology to that in Pak1 that is involved in binding to Rac1 and Cdc42 led to the identification of mixed lineage kinase 3 (MLK3), also known as protein-tyrosine kinase 1, as a potential candidate for this function. In this study, we found that MLK3 overexpression is sufficient to activate JNK potently without affecting the phosphorylating activity of MAPK or p38. Furthermore, we present evidence that MLK3 binds the GTP-binding proteins Cdc42 and Rac1 in vivo and that MLK3 mediates activation of MEKK-SEK-JNK kinase cascade by Rac1 and Cdc42. Taken together, these findings strongly suggest that members of the novel MLK family of highly related kinases link small GTP-binding proteins to the JNK signaling pathway.

Animals↗
PubMed1996

Molecular design of inhibitors of in vitro oriC DNA replication based on the potential to block the ATP binding of DnaA protein.

DnaA protein, the initiation factor for chromosomal DNA replication in Escherichia coli, is activated by binding to ATP. We earlier reported that 3-acetoxy-2,2'-bi-1H-indol inhibited the ATP binding to DnaA protein (Sasaki, S., Mizushima, T., Hashimoto, T., Maeda, M., and Sekimizu, K. (1994) Bioorg. Med. Chem. Lett. 4, 1771-1774). In the present study, derivatives of 3-acetoxy-2,2'-bi-1H-indol with different lengths of aliphatic chains at the 3-O position were synthesized, and their potential to inhibit the ATP binding to DnaA protein was examined. Elongation of the aliphatic chain resulted in inhibition of the ATP binding to DnaA protein at lower concentrations. Among the derivatives, 3-[N-(11-carboxyundecyl)]carbamoylmethoxy-2,2'-bi-1H-indol (structure 7 (3-CUCM-BI)) exhibited the most potent inhibition with an IC50 value of 7 microM. The mode of the inhibition was competitive. We further demonstrated that structure 7 (3-CUCM-BI) inhibited DNA replication of the oriC plasmid in a system reconstituted from purified proteins. This inhibition was specific for the initiation of DNA replication rather than for the elongation. The inhibition was overcome by preincubation of DnaA protein with ATP. Furthermore, structure 7 (3-CUCM-BI) showed little inhibition on DNA synthesis in the ABC primosome system. We propose that structure 7 (3-CUCM-BI) functions in the in vitro oriC DNA replication by inhibiting the ATP binding to DnaA protein.

Adenosine Triphosphate↗
PubMed1996

Heat shock-induced DNA relaxation in vitro by DNA gyrase of Escherichia coli in the presence of ATP.

Genetic studies revealed that DNA gyrase seems to catalyze immediate and transient DNA relaxation after Escherichia coli cells are exposed to heat shock (Ogata, Y., Mizushima, T., Kataoka, K., Miki, T., and Sekimizu, K. (1994) Mol. Gen. Genet. 244, 451-455). We have now obtained biochemical evidence to support this hypothesis. DNA gyrase catalyzed an increase in the linking number of DNA and relaxation of negatively supercoiled DNA, under physiological concentrations of ATP. Analyses by gel filtration chromatography of each subunit revealed that DNA relaxation activity co-migrated with each subunit. The linking number of DNA increased as the temperature increased. Further, the reaction was inhibited by nalidixic acid or by oxolinic acid. Based on these results, we propose that DNA gyrase participates in a concerted reaction with DNA topoisomerases in the immediate relaxation of DNA in cells exposed to heat shock.

Adenosine Triphosphate↗
PubMed1996

Molecular cloning of two novel rab genes from human melanocytes.

We isolated the genes of two small GTP-binding proteins of the rab family from a human melanocyte cDNA library and from melanoma cells. One gene, rab30 codes for a novel rab protein of 203 amino acids with minimal homology to previously documented GTPases. The other, rab22b, appears to be an isoform of the human homologue of canine rab22. Both rab mRNAs displayed a nearly ubiquitous pattern of expression in the various tissues examined. Rab22b and rab30 were mapped to chromosomes 18 and 11, respectively.

Amino Acid Sequence↗
PubMed1996

Characterization of the cDNA and gene encoding human PDE3B, the cGIP1 isoform of the human cyclic GMP-inhibited cyclic nucleotide phosphodiesterase family.

Two distinct PDE3 [cyclic GMP-inhibited cyclic nucleotide phosphodiesterase (cGI PDE)] isoforms, cGIP1 and cGIP2, have been identified. Here we report cloning of the cDNA and gene encoding human (H)cGIP1 (classified as PDE3B). The cDNA encodes a protein of 1112 amino acids (approximately 123 kDa). Northern blots indicate that its mRNA is expressed in several adipose tissue depots. The human PDE3B gene is composed of 16 exons spanning more than 114 kb and was localized to chromosome 11p15 by in situ hybridization. Exon/intron boundaries were determined, and genetic polymorphism, confirmed by single-strand conformational polymorphism of DNA from 25 healthy subjects, was demonstrated in exon 4 at nucleotide 1389 (A/G). Two polymorphic dinucleotide repeat sequences were identified in introns 5 and 12.

Amino Acid Sequence↗
PubMed1996

Phenotypes of dnaA mutants of Escherichia coli sensitive to phenothiazine derivatives.

The activation of DnaA protein by cardiolipin is inhibited by fluphenazine in vitro. We therefore examined the sensitivity of temperature-sensitive dnaA mutants of Escherichia coli to fluphenazine and other phenothiazine derivatives. Among the eight dnaA mutants tested, dnaA5, dnaA46 dnaA602, and dnaA604, mutants with mutations in the putative ATP binding site of DnaA protein, showed higher sensitivities to phenothiazine derivatives than did the wild-type strain. The dnaA508 and dnaA167 mutants, which have mutations in the N-terminal region of DnaA protein, also showed higher sensitivities to phenothiazine derivatives. On the other hand, the dnaA204 and dnaA205 mutants, with lesions in the C-terminal region of the DnaA protein, showed the same sensitivity to phenothiazine derivatives as the wild-type strain. Complementation analysis with a plasmid containing the wild-type dnaA gene and phage P1-mediated transduction confirmed that dnaA mutations are responsible for these sensitivity phenotypes.

Bacterial Proteins↗
PubMed1996

FRAG1, a gene that potently activates fibroblast growth factor receptor by C-terminal fusion through chromosomal rearrangement.

A constitutively active form of fibroblast growth factor 2 (FGFR2) was identified in rat osteosarcoma (ROS) cells by an expression cloning strategy. Unlike other tyrosine kinase receptors activated by N-terminal truncation in tumors, this receptor, FGFR2-ROS, contains an altered C terminus generated from chromosomal rearrangement with a novel gene, designated FGFR activating gene 1 (FRAG1). While the removal of the C terminus slightly activates FGFR2, the presence of the FRAG1 sequence drastically stimulates the transforming activity and autophosphorylation of the receptor. FGFR2-ROS is expressed as a unusually large protein and is highly phosphorylated in NIH 3T3 transfectants. FRAG1 is ubiquitously expressed and encodes a predicted protein of 28 kDa lacking significant structural similarity to known proteins. Epitope-tagged FRAG1 protein showed a perinuclear localization by immunofluorescence staining. The highly activated state of FGFR2-ROS appears to be attributed to constitutive dimer formation and higher phosphorylation level as well as possibly altered subcellular localization. These results indicate a unique mechanism of receptor activation by a C terminus alteration through a chromosomal fusion with FRAG1.

3T3 Cells↗
PubMed1996

Narrowing the position of the Werner syndrome locus by homozygosity analysis-extension of homozygosity analysis.

Werner syndrome (WS) is an autosomal recessive disorder characterized by the premature occurrence of many age-related features. Previously, the WS gene (WRN) was mapped between D8S131 and D8S87, in an 8.3-cM interval. In this study, regions of homozygosity in 36 WS patients from inbred families were searched for by genotyping for 35 dinucleotide repeat polymorphic markers to narrow down the WRN critical region. The region most consistently homozygous in these patients was between the D8S1219/D8S1220 cluster and D8S278, within a 4.4-cM interval. For 16 markers mapped in this interval, 24 WS patients (22 Japanese patients and 2 Caucasian patients) in whom consanguinity failed to be proved were also genotyped, under the assumption that some of these patients might still be from consanguineous marriages. The data were analyzed by Fisher's exact test with a 2 x 2 contingency table for the 22 Japanese patients, excluding the 2 Caucasian patients. The frequencies of homozygosity in the 22 patients at 10 of 16 markers tested were significantly higher than those detected in the general population. Analysis of homozygosity patterns indicated that the region most consistently homozygous was between D8S1445 and D8S278. Thus the WRN locus is most likely between the two markers D8S1445 and D8S278, in a 1.6-cM interval.

Asian People↗
PubMed1996

A 718-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 12.7-28.0 min region on the linkage map.

The 718,122 base pair sequence of the Escherichia coli K-12 genome corresponding to the region from 12.7 to 28.0 minutes on the genetic map is described. This region contains at least 681 potential open reading frames, of which 277 (41%) have been previously identified, 147 (22%) are homologous to other known genes, 139 (20%) are identical or similar to the hypothetical genes registered in databases, and the remaining 118 (17%) do not show a significant similarity to any other gene. In this region, we assigned a cluster of cit genes encoding multienzyme citrate lyase, two clusters of fimbrial genes and a set of lysogenic phage genes encoding integrase, excisionase and repressor in the e14 genetic element. In addition, a new valine tRNA gene, designated valZ, and a family of long directly repeated sequences, LDR-A, -B and -C, were found.

DNA, Bacterial↗