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Y Hibiya

Publications and source records attributed to Y Hibiya.

11 recordsLinked to original sources
PubMed2000

Inhibition by parthenolide of phorbol ester-induced transcriptional activation of inducible nitric oxide synthase gene in a human monocyte cell line THP-1.

Excessive nitric oxide production by inducible nitric oxide synthase (iNOS) in stimulated inflammatory cells is thought to be a causative factor of cellular injury in inflammatory disease states. Compounds inhibiting iNOS transcriptional activity in inflammatory cells are potentially anti-inflammatory. An assay method for estimating iNOS transcriptional activity in the human monocyte cell line THP-1 was established using a luciferase reporter gene system. In this study, we demonstrate that parthenolide, the predominant sesquiterpene lactone in European feverfew (Tanacetum parthenium), exerts potent inhibitory effects on the promoter activity of the iNOS gene in THP-1 cells. Parthenolide effectively suppressed iNOS promoter activity in a dose-dependent manner at concentrations higher than 2. 5 microM, with an IC(50) of about 10 microM. A tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), significantly increased the iNOS promoter-dependent reporter gene activity, and the TPA-induced increase in iNOS promoter activity was effectively suppressed by parthenolide, with an IC(50) of approximately 2 microM. The present findings may further explain the anti-inflammatory property of parthenolide.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Inhibition by berberine of cyclooxygenase-2 transcriptional activity in human colon cancer cells.

The enzyme cyclooxygenase-2 (COX-2) is abundantly expressed in colon cancer cells and plays a key role in colon tumorigenesis. Compounds inhibiting COX-2 transcriptional activity have therefore potentially a chemopreventive property against colon tumor formation. An assay method for estimating COX-2 transcriptional activity in human colon cancer cells was established using a beta-galactosidase reporter gene system, and examination was made of various medicinal herbs and their ingredients for an inhibitory effect on COX-2 transcriptional activity. We found that berberine, an isoquinoline alkaloid present in plants of the genera Berberis and Coptis, effectively inhibits COX-2 transcriptional activity in colon cancer cells in a dose- and time-dependent manner at concentrations higher than 0.3 microM. The present findings may further explain the mechanism of anti-inflammatory and anti-tumor promoting effects of berberine.

Berberine↗
PubMed1999

Inhibition of activator protein 1 activity by berberine in human hepatoma cells.

Activator protein 1 (AP-1) is a transcription factor which plays a critical role in inflammation and carcinogenesis. The present study was conducted to investigate the effect of berberine, an isoquinoline alkaloid present in plants of the genera Berberis and Coptis, on the activity of AP-1 using a reporter gene assay in human hepatoma cells. Berberine was shown to inhibit AP-1 activity in a dose- and time-dependent manner at concentrations higher than 0.3 microM. Berberine inhibited AP-1 activity almost completely as low as 10 microM after 48 h treatment. The inhibitory effect on AP-1 activity in cancer cells may further explain the anti-tumor promoting activity of berberine.

Berberine↗
PubMed1997

[Study of rat maf-related gene products: recognition DNA sequences and heterodimer-formation].

The v-maf oncogene, originally identified as the transforming gene of the avian retrovirus AS42, encodes a protein with a basic-leucine zipper (bZIP) structure which is a typical motif for protein dimerization and DNA binding. The v-Maf protein forms homodimers and sometimes heterodimers with some bZIP proteins and works as a transcription factor. Recent studies of tissue-specific expression of cellular Maf family proteins suggest that Maf-related proteins play important roles in early development and cell differentiation. In our previous studies, two maf-related cDNA clones, maf-1 and maf-2, have been isolated from a rat liver cDNA library which facilitates the investigation of physiological roles of Mafs as well as their target genes in mammals. We determine here the binding DNA sequences of Maf-1 and Maf-2, respectively. Maf-1 recognizes a number of sequences containing a short consensus sequence, -GCTGAC-, half of the Maf recognition element (MARE) which has been previously identified for V-Maf. On the other hand, binding sequences of Maf-2 are limited and Maf-2 binds to the MARE preferentially. It is shown that dimer-forming specificities of Maf-1 and Maf-2 to Jun or Fos family proteins are variable. Maf-1 efficiently forms heterodimers with Fos family proteins. Compared to the case of Maf-2, though the DNA-binding specificity of the heterodimer depends on the kind of counterpart binding to Maf-1, a wide variety of target sequences are available for Maf-1. In contrast, Maf-2 shows restricted heterodimer-forming specificity and DNA-binding specificity, so that the target genes for Maf-2 are considered to be much more limited.

Amino Acid Sequence↗
PubMed1995

The C-terminal region, Arg201-Gln209, of glutathione S-transferase P contributes to stability of the active-site conformation.

The C-terminal region of rat glutathione S-transferase P (GST-P) was deleted by either carboxypeptidase (CPase) A and B or site-specific truncation to evaluate the role of the region in the catalytic mechanism. The C-terminal sequence from the 201st to 209th amino-acid residues is Arg-Pro-Ile-Asn-Gly-Asn-Gly-Lys-Gln. When seven of the C-terminal amino-acid residues from the C-terminus were removed by the CPases, the catalytic activity decreased in parallel with the amino-acid removal, amounting to less than 5% of that of the wild-type GST-P. On the other hand, a decrease of the catalytic activity was observed in a different manner when the C-terminal sequence was site-specifically truncated. The VmaxGSH/KmGSH values of the mutants withthree (GSTd207-209), four (GSTd206-209) and seven (GSTd203-209) C-terminal amino-acid residues deleted, were comparable or similar to that of the wild-type GST-P, whereas those of five (GSTd205-209), six (GSTd204-209), and eight (GSTd202-209) amino-acid residue-truncated mutants decreased to 43%, 40%, and 19% of that of the wild-type GST-P, respectively. Similar results were obtained as for VmaxCDNB/KmCDNB. The nine amino-acid residue-truncated mutant showed no catalytic activity. Heat treatment at 50 degrees C for 5 min had little effect on the catalytic activities of the wild-type GST-P and GSTd204-209, whereas those of GSTd207-209, GSTd206-209, GSTd203-209 and GSTd202-209 decreased to 22%, 27%, 18% and 10%, respectively, compared to the catalytic activity of the non-treated enzymes. Considering these results, it is concluded that the C-terminal region, Arg201-Gln209, has an important role in stabilizing the active-site conformation.

Amino Acid Sequence↗
PubMed1994

Glutathione binding rat liver 13k protein is the homologue of the macrophage migration inhibitory factor.

We have cloned the cDNA of the rat liver 13k protein, that has glutathione binding activity, from a rat liver cDNA library. The nucleotide sequence of this cDNA predicts a protein of 115 amino acids. This protein has 99.1%, 89.6% and 73.0% homology with mouse, human and chicken macrophage migration inhibitory factor (MIF), respectively. This indicates that the rat liver 13k protein is homologue of the MIF. The N-terminal 25 amino acids show 35% sequence similarity with that of the rat glutathione transferase Yb subunit. Although the remaining C-terminal sequence has no sequence identity with glutathione transferase Yb subunit, about 50% homology was found, if conservative substitutions and gaps were taken into account. Northern blot analysis indicates that this gene is expressed in a wide variety of organs including brain, spleen, liver, muscle and kidney. Southern blot analysis suggests that the MIF gene has many pseudo-genes or/and closely related genes.

Amino Acid Sequence↗
PubMed1993

Haplotype diversity in the human red and green opsin genes: evidence for frequent sequence exchange in exon 3.

We studied polymorphisms in the coding sequences of the human red and green opsin genes of 133 Caucasian males. Eleven polymorphic sites were discovered in the red opsin gene, seven of which were in exon 3, three in exon 4 and one in exon 5. Polymorphisms at 8 of these sites resulted in amino acid substitutions which generated a total of 18 unique red opsins in the population. The substitutions at three (S180A, I230T, and A233S) of the 8 sites involve hydroxyl-bearing to non-polar amino acid residues, and are therefore likely to alter spectral characteristics of the red pigment. Eight polymorphic sites were observed in the green opsin coding sequences, six of which were in exon 3, one in exon 2 and one in exon 5. Five of the eight involved amino acid substitutions which generated 15 unique green opsins in the population. Substitutions at two of these sites involve hydroxyl-bearing vs. non-polar residues. Six polymorphisms, all of which are located in exon 3, are shared between the red and green opsin genes, essentially making it difficult to assign this exon to either of these genes. Markers in exon 3 are in partial linkage disequilibrium with those in exons 4 and 5, whereas the latter two are in strong linkage disequilibrium with each other. Furthermore, markers in the 5' region of exon 3 are also in only partial (54%) disequilibrium with those in the 3' region. The above results strongly suggest a history of frequent gene conversion, mainly localized to exon 3, in the lineages leading to the human red and green opsin genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Genotype-phenotype relationships in human red/green color-vision defects: molecular and psychophysical studies.

The relationship between the molecular structure of the X-linked red and green visual pigment genes and color-vision phenotype as ascertained by anomaloscopy was studied in 64 color-defective males. The great majority of red-green defects were associated with either the deletion of the green-pigment gene or the formation of 5' red-green hybrid genes or 5' green-red hybrid genes. A rapid PCR-based method allowed detection of hybrid genes, including those undetectable by Southern blot analysis, as well as more precise localization of the fusion points in hybrid genes. Protan color-vision defects appeared always associated with 5' red-green hybrid genes. Carriers of single red-green hybrid genes with fusion in introns 1-4 were protanopes. However, carriers of hybrid genes with red-green fusions in introns 2, 3, or 4 in the presence of additional normal green genes manifested as either protanopes or protanomalous trichromats, with the majority being protanomalous. Deutan defects were associated with green-pigment gene deletions, with 5' green-red hybrid genes, or, rarely, with 5' green-red-green hybrid genes. Complete green-pigment gene deletions or green-red fusions in intron 1 were usually associated with deuteranopia, although we unexpectedly found three carriers of a single red-pigment gene without any green-pigment genes to be deuteranomalous trichromats. All but one of the other deuteranomalous subjects had green-red hybrid genes with intron 1, 2, 3, or 4 fusions, as well as several normal green-pigment genes. The one exception had a grossly normal gene array, presumably with a more subtle mutation. Amino acid differences in exon 5 largely determine whether a hybrid gene will be more redlike or more greenlike in phenotype. Various discrepancies as to severity (dichromacy or trichromacy) remain unexplained but may arise because of variability of expression, postreceptoral variation, or both. When phenotypic color-vision defects exist, the kind of defect (protan or deutan) can be predicted by molecular analysis. Red-green hybrid genes are probably always associated with protan color-vision defects, while the presence of green-red hybrid genes may not always manifest phenotypically with color-vision defects. Four subjects who were found to have 5' green-red hybrid genes in addition to normal red- and green-pigment genes had normal color vision as determined by anomaloscopy. These were discovered among a group of 129 Caucasian males who had been recruited as volunteers for a vision study.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗
PubMed1991

Enhancing protein engineering capabilities by combining mutagenesis and semisynthesis.

If site-directed mutagenesis could be used to facilitate protein semisynthesis, then structural engineering goals should be achieved that are unattainable by either technique alone. We tested this possibility by mutating Ser65 of yeast cytochrome c to methionine, creating a new site for CNBr cleavage. Fragments obtained by cleaving there were found to refold cooperatively, bringing together the breakpoint termini and leading to efficient autocatalytic peptide bond synthesis. Structurally modified fragments may be substituted for natural ones. Generally, naturally occurring sites are unsuitable for autocatalytic religation, for reasons briefly discussed, and thus the power of this new approach lies in the freedom to choose sites, including enzymatic ones, that are appropriate to the semisynthetic goals.

Amino Acid Sequence↗