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M Iwabuchi

Publications and source records attributed to M Iwabuchi.

At least 73 records · Page 4Linked to original sources
PubMed1995

A far-upstream sequence of the wheat histone H3 promoter functions differently in rice and tobacco cultured cells.

The cis-regulatory function of a far-upstream sequence (-1,711 to -186) of the promoter of the wheat gene for histone H3 (TH012) was analyzed in cultured rice and tobacco cells in a transient expression system with the gene for beta-D-glucuronidase as a reporter gene. The far-upstream sequence was necessary for full activity of the H3 promoter in rice cells but did not enhance the activity of the proximal promoter in tobacco cells. Dissection analysis of the far-upstream sequence revealed the existence of several positive and negative cis-acting sequences in this region, some of which functioned differently in rice and tobacco cells. In gain-of-function experiments with rice cells, the sequence from -848 to -704, containing the CCAAT and octamer (CaCGGATC) motifs, functioned in an orientation-independent manner, whereas the sequence from -703 to -486 functioned in an orientation-dependent manner. By contrast, both sequences exhibited an orientation-dependent cis-function in tobacco cells. These findings suggest that some cis-regulatory sequences in the far-upstream region of the H3 promoter function differently in rice and tobacco cells.

Base Sequence↗
PubMed1995

Potential transcription regulatory sequences in a promoter region of the wheat basic/leucine zipper protein HBP-1b(c38) gene.

A gene encoding the wheat transcription factor HBP-1b(c38) and its promoter region have been structurally analyzed. Protein-DNA interaction studies indicated the specific binding of the hexamer motif ACGTCA found in the promoter to the HBP-1b isoforms including HBP-1b(c38), suggesting that transcription of the HBP-1b(c38) gene may be autoregulated.

Base Sequence↗
PubMed1995

Plant transcription factors.

Transcriptional regulation of gene expression relies on the recognition of promoter elements by transcription factors. In the past several years, a considerable number of (putative) transcription factors have been identified in plants. Some genes coding for these factors were isolated by south-western screening with oligonucleotides as a probe or by homology-based screening, and others were initially isolated by genetic means and subsequently identified as the genes for transcription factors. These transcription factors often form families of structurally related proteins with similar DNA-binding specificities and in addition, they are sometimes involved in related phenomena. Some groups of factors homo- and/or heterodimerize to increase the length and variability of the target sequences. Transcriptional activators, in general, comprise a modular activation domain. The activities of the transcription factors are controlled by post-translational modification, like phosphorylation and glycosylation, as well as at the levels of nuclear transport, oligomerization, etc. In this review, we will summarize the current knowledge of plant transcription factors to help understand the mechanistic aspects of the transcriptional regulation of genes.

Amino Acid Sequence↗
PubMed1994

The HBP-1 family of wheat basic/leucine zipper proteins interacts with overlapping cis-acting hexamer motifs of plant histone genes.

The type I element (CCACGTCANCGATCCGCG) is a cis-acting element that is essential for the transcriptional regulation of the wheat histone H3 (TH012) gene. The sequence CCACGTCA in the type I element resembles various plant regulatory elements that share an ACGT core sequence, which can be recognized by different basic/leucine zipper (bZIP) proteins. Here we describe the isolation and characterization of wheat cDNA clones encoding three novel bZIP proteins, designated HBP (histone promoter-binding protein)-1a(1), HBP-1a(c14), and HBP-1b(c1). These proteins specifically bind to the ACGT core sequence and, together with previously identified HBP-1a(17) and HBP-1b(c38), constitute a protein family, named the HBP-1 family. Based on their structural characteristics and DNA binding specificities, members of the HBP-1 family can be grouped into HBP-1a and HBP-1b subfamilies. The HBP-1a isoforms are characterized by their N-terminal proline-rich domain and a C-terminal bZIP domain, which binds to the CCACGT motif. In contrast, the HBP-1b isoforms have a bZIP domain at the N terminus, which binds to the ACGTCA motif, and a glutamine-rich domain at the C terminus. All members of both subfamilies interact with the CCACGTCA sequence, but their DNA binding specificities and affinities differ. Since HBP-1a isoforms form heterodimers in all pairwise combinations, heterodimer formation among these bZIP proteins may generate an expanded repertoire of regulatory potential for gene expression in plants.

Amino Acid Sequence↗
PubMed1994

The conserved 3'-flanking sequence, AATGGAAATG, of the wheat histone H3 gene is necessary for the accurate 3'-end formation of mRNA.

We examined the 3'-flanking regions required for accurate 3'-end formation of wheat histone H3 mRNA using gene expression in transformed sunflower cells. The introduction of mutations into the conserved sequence AATGGAAATG in the 3'-flanking region of plant histone genes, located 22 bp upstream from the polyadenylation site of the wheat H3 gene (TH012), completely abolished the 3'-end formation of mRNA at the authentic 3' end without affecting the transcription efficiency. However, a 0.8 kbp sequence containing this motif could not produce a normal 3' end when joined to the 3' end of the nopaline synthase (NOS) gene instead of its 3' sequence. The results indicated that this conserved sequence is necessary but not sufficient for the 3'-end formation of H3 or NOS mRNA. Deletion of a 59 bp sequence, located 19 bp upstream from the AATGGAAATG sequence, also reduced the 3'-end formation efficiency by a factor of 10, compared with the efficiency in wild-type gene. We concluded that 3'-end formation of wheat histone H3 mRNA is regulated by multiple sequences including the AATGGAAATG motif.

Amino Acid Oxidoreductases↗
PubMed1994

The propagation of a porcine hemagglutinating encephalomyelitis virus in swine kidney cell cultures.

An established cell line, KSEK6, derived from swine embryo kidney proved to be a suitable host for the propagation of a hemagglutinating encephalomyelitis virus, strain 67N. Infected cells showed clear cytopathic effect as early as 24 hours incubation at 37 degrees C. Plaques easily visible to the naked eye were also produced under agar overlay medium. The infective titer of 3rd passage level in the cells was in the order of 10(8) PFU per ml. Detecting antibodies against this virus strain in swine sera was considered to be more accurate by neutralization test than by hemagglutination inhibition.

Animals↗
PubMed1993

The putative zinc-finger protein WZF1 interacts with a cis-acting element of wheat histone genes.

A nonamer motif (CATCCAACG) that is one of the cis-acting elements identified in the proximal promoter region of some wheat histone genes is included in the region that interacts with the wheat DNA-binding protein, HBP (histone gene-binding protein)-2. To obtain structural and functional information about this DNA-binding protein, we attempted to isolate a cDNA clone encoding HBP-2 on the basis of its ability to bind to a nonamer-containing 38-bp DNA fragment. Southwestern screening of a wheat cDNA library with concatenated 38-residue oligonucleotides as the probe produced one candidate clone. Nucleotide sequence analyses of this cDNA clone and the corresponding genomic clone showed that the protein deduced from the nucleotide sequence consisted of 261 amino acids and contained a set of zinc-finger motifs similar to those found in many eukaryotic transcription factors. The protein, named WZF1 (wheat zinc-finger protein 1), which was expressed from the cDNA in Escherichia coli cells, bound specifically and metal-ion-dependently to the nonamer-containing oligonucleotide. The WZF1 mRNA was highly expressed in the root apexes of wheat seedlings, but less so in the proximal portion of young leaves; whereas, histone H3 mRNA was highly expressed in both tissues. The expression patterns of the WZF1 and histone H3 genes in the early stages of germination differed, expression of the WZF1 gene being almost constant but not that of the H3 gene. The relationship of WZF1 and HBP-2 and the possible role of WZF1 in the histone gene expression were discussed.

Amino Acid Sequence↗
PubMed1993

Processing followed by complete editing of an altered mitochondrial atp6 RNA restores fertility of cytoplasmic male sterile rice.

Two atp6 genes were found in the mitochondrial genome of cytoplasmic male sterile (CMS) rice carrying the [cms-bo] cytoplasm. One (N-atp6) was identical to the normal cytoplasmic gene, while the second (B-atp6) was identified as a candidate CMS gene by Southern analysis of the mitochondrial genome of CMS cybrid rice. The coding sequence of B-atp6 was identical to the normal N-atp6 gene but its 3'-flanking sequence was different starting at 49 bases downstream from the stop codon. Northern analysis showed that B-atp6 is transcribed into a 2.0 kb RNA in the absence of the Rf-1 gene, whereas two discontinuous RNAs, of approximately 1.5 and 0.45 kb, were detected in the presence of the Rf-1 gene. Determination of the 3' and 5' ends of these RNAs suggested that the two discontinuous RNAs were generated from the 2.0 kb RNA by RNA processing at sites within the B-atp6-specific sequences by the action of the Rf-1 gene. Sequence analysis of cDNA clones derived from the N-atp6 RNA and the processed and unprocessed RNAs of B-atp6 indicated that the processed B-atp6 RNAs were edited as efficiently as the N-atp6, whereas unedited and partially edited RNAs were detected among unprocessed RNAs. RNA processing by Rf-1 thus influences the sequential post-transcriptional editing of the B-atp6 RNAs. Because the unprocessed RNAs of B-atp6 are possibly translated into altered polypeptides, our results suggest that interaction of RNA processing and editing plays a role in controlling CMS expression and the restoration of fertility in rice.

Amino Acid Sequence↗
PubMed1993

Proximal promoter region of the wheat histone H3 gene confers S phase-specific gene expression in transformed rice cells.

The cis-regulatory elements that confer cell cycle-dependent expression to the wheat histone H3 gene were investigated in rice cells (Oc strain) transformed with H3/GUS chimeric genes. 5' deletion mutants of the H3 promoter region (from -1711, -908 or -185 to +57 relative to the transcription start site) were joined to the coding sequence of the bacterial beta-glucuronidase (GUS) gene then introduced stably into rice cells. S1 analyses of the RNA from transformed rice cells whose cell cycles had been synchronized by treatment with aphidicolin showed that the steady-state levels of the transcripts from chimeric genes were altered with the change in DNA synthesis and the content of rice H3 mRNA throughout the cell cycle. Even though H3 promoter activity decreased as 5' deletion proceeded, transcripts from the chimeric genes showed increases, as much as 10-fold 1 h after release from the aphidicolin block, which were rapidly lost over the next 4 h. The results suggest that the 242 bp sequence from -185 to +57, which contains the basal promoter region, confers the S phase-specific expression of the H3 gene and that the upstream sequence from position -186 is required for the full activity of this promoter.

Base Sequence↗
PubMed1993

Coordinate gene expression of five subclass histones and the putative transcription factors, HBP-1a and HBP-1b, of histone genes in wheat.

The expression of genes encoding five histones (H1, H2A, H2B, H3 and H4) and the putative transcription factors HBP-1a (17) and HBP-1b (c38) was examined during early germination and in various tissues of young wheat seedlings. The steady-state levels of core histone (H2A, H2B, H3 and H4) mRNAs were coordinately cell cycle-dependent and paralleled the rate of DNA synthesis during early germination, whereas the expression pattern of the linker histone (H1) genes differed. The five subclass histone genes were actively expressed in the meristematic tissues of young seedlings. Moreover, H1 genes were expressed in leaves that consist mostly of non-proliferating cells, in which core histone genes showed little expression. Quantitative alterations to the mRNAs of the putative transcription factors HBP-1a (17) and HBP-1b (c38) of wheat histone genes were similar to those of the core histone mRNAs, suggesting that both factors function in the cell cycle-dependent expression of wheat core histone genes.

Base Sequence↗
PubMed1993

Chromosomal locations of the genes for histones and a histone gene-binding protein family HBP-1 in common wheat.

The chromosomal locations of the genes in common wheat that encode the five histones and five members of the HBP (histone gene-binding protein)-1 family were determined by hybridizing their cloned DNAs to genomic DNAs of nullitetrasomic and telosomic lines of common wheat, Triticum aestivum cv. Chinese Spring. The H1 and H2a genes are located on different sets of homoeologous chromosomes or chromosome arms, namely, 5A, 5B and 5D, and 2AS, 2BS and 2DS, respectively. Genes for the other histones, H2b, H3 and H4, are found in high copy number and are dispersed among a large number of chromosomes. The genes for all members of the HBP-1 family are present in small copy numbers. Those for HBP-1a(1) are located on six chromosome arms, 3BL, 5AL, 5DL, 6AL, 6BS and 7DL, whereas those for each HBP-1a(c14), 1a(17), 1b(c1), and 1b(c38) are on a single set of homoeologous chromosome arms; 4AS, 4BL, 4DL; 6AS, 6BS, 6DS; 3AL, 3BL, 3DL; and 3AS, 3BS, 3DS, respectively. The genes for histones H1 and H2a, and for all members of the HBP-1 family except HBP-1a(1) are assumed to have different phylogenetic origins. The genes for histone 2a and HBP-1a(17) are located in the RFLP maps of chromosomes 2B and 6A, respectively. Gene symbols are proposed for all genes whose chromosomal locations have been determined.

Aneuploidy↗
PubMed1993

Serial angiographic follow-up after Palmaz-Schatz stent implantation: comparison with conventional balloon angioplasty.

OBJECTIVES: Serial angiographic follow-up study was designed to evaluate the temporal mode of lumen diameter changes after Palmaz-Schatz stent implantation, and the results were compared with those from a cohort of patients undergoing balloon angioplasty. BACKGROUND: Restenosis remains a major limitation of balloon angioplasty. The Palmaz-Schatz balloon expandable coronary stent is now under clinical investigation to evaluate its efficacy in preventing restenosis. METHODS: Serial angiographic follow-up study was performed the day after stent implantation and at 1, 3 and 6 months after the procedure. The stent group consisted of 96 patients who had 97 lesions with a single stent. A cohort of 179 patients with 192 lesions were selected as the balloon group by the criteria of final balloon size > or = 3 mm and lesion length < 20 mm. RESULTS: A significantly larger lumen diameter was obtained immediately after stent implantation (2.9 +/- 0.4 mm [mean +/- SD] in the stent group vs. 2.1 +/- 0.5 mm in the balloon group, p < 0.001). At 3 to 6 months of follow-up, a significantly larger lumen diameter was maintained in the stent group (2.2 +/- 0.6 vs. 1.5 +/- 0.7 mm, p < 0.001). The late restenosis rate according to a binary definition was significantly lower in the stent group (13% vs. 39%, p < 0.001). Stenosis exacerbation, frequently observed within 24 h after balloon angioplasty, was not found after stenting. Between the next day and 1 month, regression was dominant in the balloon group, whereas progression of stenosis was observed in the stent group. The greatest tendency to restenosis was observed in both groups between 1 and 3 months after the procedure. Between 3 and 6 months, significantly greater diameter loss was found in the stent group. CONCLUSIONS: The Palmaz-Schatz stent was effective in reducing the restenosis rate in this highly selected cohort of patients. Reduction in restenosis rate was dependent on a larger lumen obtained immediately. Late loss of diameter was significantly greater after stenting. The restenosis rate after stenting should be evaluated by follow-up angiography at 6 months rather than at 3 months, which is adequate after conventional balloon angioplasty.

Adult↗
PubMed1993

A wheat histone H3 promoter confers cell division-dependent and -independent expression of the gus A gene in transgenic rice plants.

To investigate developmental regulation of wheat histone H3 gene expression, the H3 promoter, which has its upstream sequence to -1711 (relative to the cap site as +1), was fused to the coding region of the gus A gene (-1711H3/GUS) and introduced into a monocot plant, rice. Detailed histochemical analysis revealed two distinct types of GUS expression in transgenic rice plants; one is cell division-dependent found in the apical meristem of shoots and roots and in young leaves, and another is cell division-independent detected in flower tissues including the anther wall and the pistil. In this study, replication-dependent expression occurring in non-dividing cells which undergo endoreduplication could not be discriminated from strict replication-independent expression. The observed expression pattern in different parts of roots suggested that the level of the H3/GUS gene expression is well correlated with activity of cell division in roots. To identify 5' sequences of the H3 promoter necessary for an accurate regulation of the GUS expression, two constructs containing truncated promoters, -908H3/GUS and -185H3/GUS, were analyzed in transiently expressed protoplasts, stably transformed calli and transgenic plants. The results indicated that the region from -909 to -1711 contains the positive cis-acting element(s) and that the proximal promoter region (up to -185) containing the conserved hexamer, octamer and nonamer motifs is sufficient to direct both cell division-dependent and -independent expression. The use of the meristem of roots regenerated from transformed calli for the analysis of cell division-dependent expression of plant genes is discussed.

Base Sequence↗
PubMed1993

A nuclear factor that binds to a dyad-symmetric sequence with a CGTCA motif in the 5'-upstream region of the sweet potato beta-amylase gene.

A nuclear extract from petioles of sweet potato protected several sites in the 5'-upstream region of a gene for beta-amylase from DNase I digestion. One of these sites, located at a region around 800-base pairs upstream from the transcription start site, having an imperfect palindromic sequence of CGTCACGTCACG, was designated the R-box. The site contained tandemly duplicated CGTCA sequences, referred to below as 5'- and 3'-CGTCA. Competition experiments in gel mobility shift assays with mutant R-box oligonucleotides indicated that mutations in bases outside the 3'-CGTCA of the R-box do not severely affect the binding. By contrast, single-base substitutions in any one base of the 3'-CGTCA greatly abolished the binding even when the mutated R-boxes contained intact 5'-CGTCA. However, oligonucleotides with mutations in the 3'-CGTCA had the ability to bind the nuclear factor when additional mutations were introduced to create a partially palindromic sequence containing the CGTCA sequence in its 3'-half on the opposite strand. These results indicate that the CGTCA sequence alone is not sufficient for the binding of the R-box binding factor (RBF) and that the RBF binds to the sequence with partial dyad symmetry that contains the CGTCA motif in its 3'-half. The optimum sequence for the binding of the RBF is suggested to be a palindromic octameric sequence TGACGTCA, which is identical to the consensus sequence of the cAMP-responsive element (CRE) of animal genes. Bacterially produced HBP-1b of wheat bound to the R-box, and its binding to mutated R-boxes was similar to that of RBF, suggesting that the RBF belongs to a family of bZIP-type plant nuclear factors that bind to CGTCA-related sequences. However, several differences between the RBF and HBP-1b were also noted.

Base Sequence↗
PubMed1993

[Medical management after pituitary surgery].

Although the majority of patients with pituitary tumor, undergoing transsphenoidal microsurgery, have a low incidence of hormonal deficiency after surgery, the endocrinological evaluations should be carefully done before and after surgery. Glucocorticoid replacement is necessary in patients with Cushing's disease during and after surgery as well as those with adrenal insufficiency. Repeated CRF test is useful to assess the secondary adrenal insufficiency of Cushing's disease after surgery. Patients with impaired secretion of both ACTH and TSH should receive glucocorticoid replacement before thyroid hormone replacement in order to avoid adrenal crisis. A combination of CRF, GRF, TRH and GnRH is a safer and more reliable test to evaluate pituitary function than the conventional triple test consisting of insulin, TRH and GnRH, especially in patients predicted to have pituitary-adrenal insufficiency. Diabetes insipidus(DI), immediately after pituitary surgery, should be treated with subcutaneous injection of Pitressin. Even if patients seem to have recovered from DI several days after surgery, they must be monitored closely because of the incidence of triphasic DI. Less attention has been given to replacement for GH deficiency in adults. Recent reports revealed that GH replacement in adults with GH deficiency decreases visceral fat tissue and increases plasma calcium, phosphorus, osteocalcin and procollagen III levels. GH replacement will become more popular even in adults. Many options and technological advantages in the diagnosis and treatment of pituitary tumors have developed in a decade. In the near future, post-operative patients with pituitary tumors must be cared for in view of the "quality of life".

Adenoma↗