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Biomedical subjects

T Ohba

Publications and source records attributed to T Ohba.

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

Human sterol carrier protein x/sterol carrier protein 2 gene has two promoters.

The human sterol carrier protein x (SCPx)/sterol carrier protein 2 (SCP2) gene gives rise to two mRNAs: a 2.8 kb mRNA encoding SCPx, a peroxisome-associated thiolase, and a 1.5 kb mRNA encoding SCP2, which is thought to be an intracellular lipid transfer protein. The SCPx/SCP2 gene is highly expressed in organs involved in lipid metabolism, but the relative abundance of SCPx and SCP2 mRNAs varies. Here we report that the two transcripts are produced under the direction of two independent promoters. We determined the DNA sequence of 3.4 kb of the proximal promoter governing the transcription of SCPx sequences. The promoter governing the transcription of SCP2 sequences was identified 45 kb downstream from the SCPx promoter in intron XI. This promoter initiates transcription within exon XII. Both the SCPx and SCP2 promoters lack TATA boxes and initiate transcription at multiple sites. They share features that are found in the promoters of genes encoding other peroxisomal proteins. The basal activities of the two promoters were tested as fusion gene constructs in selected host cells, including BeWo choriocarcinoma cells, HepG2 hepatoblastoma cells, murine Y1 adrenocortical tumor cells, and Balb 3T3 fibroblasts. Cell host-specific patterns of promoter activity were observed. In addition, 8-Br-cAMP and phorbol myristate acetate were found to increase SCPx promoter activity in a host cell-specific manner. The SCP2 promoter was not significantly influenced by these agents.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1995

A giant nucleopore protein that binds Ran/TC4.

Ran/TC4 is a small nuclear G protein that forms a complex with the chromatin-bound guanine nucleotide release factor RCC1 (ref. 2). Loss of RCC1 causes defects in cell cycle progression, RNA export and nuclear protein import. Some of these can be suppressed by overexpression of Ran/TC4 (ref. 1), suggesting that Ran/TC4 functions downstream of RCC1. We have searched for proteins that bind Ran/TC4 by using a two-hybrid screen, and here we report the identification of RanBP2, a novel protein of 3,224 residues. This giant protein comprises an amino-terminal 700-residue leucine-rich region, four RanBP1-homologous (refs 9, 10) domains, eight zinc-finger motifs similar to those of NUP153 (refs 11, 12), and a carboxy terminus with high homology to cyclophilin. The molecule contains the XFXFG pentapeptide motif characteristic of nuclear pore complex (NPC) proteins, and immunolocalization suggests that RanBP2 is a constituent of the NPC. The fact that NLS-mediated nuclear import can be inhibited by an antibody directed against RanBP2 supports a functional role in protein import through the NPC.

Amino Acid Sequence↗
PubMed1995

RanBP1, a Ras-like nuclear G protein binding to Ran/TC4, inhibits RCC1 via Ran/TC4.

A human protein that is 92% identical and 97% homologous at the amino acid level to RanBP1 from mouse was identified by the two-hybrid method, using two types of target cDNAs fused to sequences encoding the GAL4 DNA-binding domain. The target cDNAs encoded the human Ran/TC4 and human RCC1 proteins, respectively. An in vitro binding experiment showed that RanBP1 binds to RCC1 with the aid of Ran. Partially purified, GST-fused RanBP1 inhibited RCC1-stimulated guanine nucleotide release from Ran in vitro. Consistent with this in vitro finding, overproduction of human RanBP1 was detrimental to growth of tsBN2, a temperature-sensitive BHK21 hamster cell line defective in the RCC1 gene, and inhibited the growth of the Saccharomyces cerevisiae rcc1 mutants prp20, mtr1 and srm1. The specific effect of RanBP1 on rcc1- cells was confirmed by the finding that overproduction of RanBP1 induces significant levels of expression of a FUS1-lacZ gene and an increase in mating efficiencies in a ste3, pheromone receptor-deficient yeast mutant. This phenotype is similar to the srm1, a mutant isolated as a suppressor that restores mating to receptorless mutants. These findings indicate that RanBP1 negatively regulates RCC1.

Amino Acid Sequence↗
PubMed1995

A case of Werner's syndrome associated with systemic lupus erythematosus.

The case of a 40-year-old woman with Werner's syndrome associated with systemic lupus erythematosus (SLE) is reported. The patient exhibited short stature, slender extremities, thinned hair, high-pitched voice, cataracts, ulceration of the fingers, and mental retardation. Malar erythema, photosensitivity, and proteinuria had been noted since age 34. The serum contained high titers of antibodies to dsDNA, Sm, nRNP, and SS-A/Ro. The simultaneous presence of Werner's syndrome and SLE could be a coincidental occurrence of the two diseases, although it might be due to an abnormality in replication or degeneration of DNA leading to the development of both diseases.

Adult↗
PubMed1995

DNA rearrangement associated with the integration of T-DNA in tobacco: an example for multiple duplications of DNA around the integration target.

Transferred DNA (T-DNA) of the tumor-inducing (Ti) plasmid is transferred from Agrobacterium tumefaciens to plant cells and is stably integrated into the plant nuclear genome. By the inverse polymerase chain reaction DNA fragments were amplified that contained the T-DNA/plant DNA junctions from the total DNA of a transgenic tobacco plant that had a single copy of the T-DNA in a repetitive region of its genome. A DNA fragment containing the target site was amplified from the total DNA of non-transformed tobacco by the polymerase chain reaction using high-stringency conditions. Comparison of the nucleotide sequence of the target site with those of the T-DNA/plant DNA junctions revealed that various duplications of short stretches of nucleotide sequences around the target and in the incoming T-DNA had accompanied the integration of the T-DNA. A deletion of 16 bp at the target site was also found and the target site was similar, in terms of nucleotide sequence, to regions around the breakpoints of the T-DNA. This finding provides a clear example of the occurrence of complex rearrangements during the integration of T-DNA.

Agrobacterium tumefaciens↗
PubMed1995

[Two cases of micrognathia caused by radiation therapy during infancy: an evaluation of their profilograms].

Two patients with micrognathia of the mandible caused by radiation therapy during infancy are reported herein. The first patient was a 25-year-old man with hemangioma of the tongue. He had previously received radiation therapy totaling 51 Gy at 1 and 2 years of age. The other patient was a 54-year-old woman who had received radiation therapy for an oral tumor during infancy. These two patients demonstrated micrognathia, and the former patient showed developmental anomaly of the teeth. In addition, the latter patient suffered from thyroid cancer at 45 years of age, and this was also thought to be radiation-related. Although reports of micrognathia caused by radiation are rare, such late effects should be taken into account when radiation therapy is planned for head and neck tumors in infants.

Adult↗
PubMed1995

Elevated levels of platelet derived growth factor and transforming growth factor-beta 1 in bronchoalveolar lavage fluid from patients with scleroderma.

OBJECTIVE: Systemic sclerosis (scleroderma, SSc) frequently affects the lungs, and interstitial pulmonary fibrosis is one of its major complications. The pathophysiology of SSc lung disease s poorly understood, but recent studies document an inflammatory process resembling that of idiopathic pulmonary fibrosis with increased numbers of activated alveolar macrophages and granulocytes in bronchoalveolar lavage (BAL) fluid). We determined levels of 2 potentially important mediators of fibroproliferative repair in BAL fluid from patients with SSc. METHODS: Using Western blot and ELISA techniques we measured levels of platelet derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta in BAL fluid from patients with SSc and healthy controls. The mitogenic effect of these cytokines on SSc lung myofibroblasts was determined by [3H]thymidine incorporation. RESULTS: SSc BAL fluid contains significantly elevated levels of PDGF-AA and PDGF-BB. Where TGF-beta 1 was significantly elevated in SSc lavage fluid, the amount of TGF-beta 2 was significantly less than that observed in normal lavage fluid. Myofibroblasts cultured from SSc lavage fluid exhibited enhanced [3H]thymidine incorporation upon exposure to the growth factors present in SSc BAL fluid: PDGF and TGF-beta 1. SSc lung myofibroblasts pretreated with TGF-beta 1 exhibited an enhanced mitogenic effect upon stimulation by PDGF, due in part to the induction of the PDGF alpha receptor. CONCLUSION: Our studies support a role for PDGF and TGF-beta 1 in the pathogenesis of SSc lung disease.

Bronchoalveolar Lavage Fluid↗
PubMed1994

A mutant form of the Ran/TC4 protein disrupts nuclear function in Xenopus laevis egg extracts by inhibiting the RCC1 protein, a regulator of chromosome condensation.

The Ran protein is a small GTPase that has been implicated in a large number of nuclear processes including transport. RNA processing and cell cycle checkpoint control. A similar spectrum of nuclear activities has been shown to require RCC1, the guanine nucleotide exchange factor (GEF) for Ran. We have used the Xenopus laevis egg extract system and in vitro assays of purified proteins to examine how Ran or RCC1 could be involved in these numerous processes. In these studies, we employed mutant Ran proteins to perturb nuclear assembly and function. The addition of a bacterially expressed mutant form of Ran (T24N-Ran), which was predicted to be primarily in the GDP-bound state, profoundly disrupted nuclear assembly and DNA replication in extracts. We further examined the molecular mechanism by which T24N-Ran disrupts normal nuclear activity and found that T24N-Ran binds tightly to the RCC1 protein within the extract, resulting in its inactivation as a GEF. The capacity of T24N-Ran-blocked interphase extracts to assemble nuclei from de-membranated sperm chromatin and to replicate their DNA could be restored by supplementing the extract with excess RCC1 and thereby providing excess GEF activity. Conversely, nuclear assembly and DNA replication were both rescued in extracts lacking RCC1 by the addition of high levels of wild-type GTP-bound Ran protein, indicating that RCC1 does not have an essential function beyond its role as a GEF in interphase Xenopus extracts.

Animals↗
PubMed1994

The structure of the human sterol carrier protein X/sterol carrier protein 2 gene (SCP2).

Sterol carrier protein X (SCPx) is a 58-kDa protein that is localized to peroxisomes. The amino acid sequence of the protein suggests that SCPx may function as a thiolase. The gene encoding SCPx also codes for a 15.3-kDa protein called sterol carrier protein 2 (SCP2). Here we report the structure of this gene (SCP2), which spans approximately 80 kb and consists of 16 exons and 15 introns. Multiple transcription start sites were identified. The 5' flanking region has characteristics of other peroxisomal protein promoters, which include the absence of a TATA box and a G+C-enriched region containing several reverse GC boxes.

Acetyl-CoA C-Acetyltransferase↗
PubMed1994

The CCG1/TAFII250 gene is mutated in thermosensitive G1 mutants of the BHK21 cell line derived from golden hamster.

The CCG1 cDNA encoding a general transcription factor, TAFII250, complements a thermosensitive (ts) cell cycle mutant, tsBN462, of the BHK21 cell line, which arrests in the G1 phase at the restrictive temperature. In order to clarify whether the CCG1 is mutated in tsBN462 cells or a suppressor of tsBN462 mutation, CCG1 cDNAs isolated from parental wild-type (wt) BHK21 and tsBN462 cell lines were sequenced. Comparison of the nucleotide (nt) sequences showed a single transition: G-->A in the second base of codon 690 of the tsBN462 CCG1 cDNA, resulting in a Gly690-->Asp change. The BHK CCG1 cDNA, but not the tsBN462 CCG1 cDNA, complemented the tsBN462 mutation, proving that the CCG1 is mutated in the tsBN462 cell line. Thus, the defect of general transcription factor, TAFII250, is suggested to cause a G1 arrest in the cell cycle.

Amino Acid Sequence↗
PubMed1994

Isolation, growth and characteristics of human ovarian surface epithelium.

The ovarian surface epithelium (OSE) is a key tissue in the pathogenesis of ovarian surface epithelial-stromal tumours and ovarian endometriosis, commonly encountered gynaecological diseases. Despite the high incidence of these diseases, experimental in vitro studies of OSE are few and so we used the scraping method with an enzymatic procedure to isolate human OSE and studied its characteristics in vitro. Nineteen normal ovaries were used. After incubation of the ovary for 40 min in collagenase type 1 solution (300 U/ml), the surface cells were removed by gentle scraping with a surgical blade. Cells obtained as a cluster after unit gravity sedimentation with 5% bovine serum albumin in medium 199 were cultured in medium 199 containing 15% fetal bovine serum. The viable cell number in a single ovary was 0.1-2.7 x 10(6). The outgrowth of cells started from a homogeneous population of single cells, and the cell population doubling time was between 7 and 10 days. Confluent monolayers were formed after 13-20 days and subcultured from one to three times. The monolayers mostly had a cobblestone appearance, and fusiform or polygonal cells were also observed. By cytochemistry, immunocytochemistry and scanning and transmission electron microscopy, the cells were shown to have characteristics of mesothelial OSE cells in short-term culture. This experimental approach was efficient in providing cultured human OSE, which can be utilized to investigate pathobiology and carcinogenesis.

Adult↗
PubMed1994

Scleroderma bronchoalveolar lavage fluid contains thrombin, a mediator of human lung fibroblast proliferation via induction of platelet-derived growth factor alpha-receptor.

In addition to its procoagulant properties, the serine protease thrombin increases endothelial permeability, stimulates granulocyte adherence, and serves as a fibroblast mitogen. We demonstrate that thrombin is mitogenic for human lung fibroblasts in vitro. The mitogenic effect of thrombin is associated with an increase in the expression of the ligand PDGF-AA and up-regulation of PDGF alpha-receptor. Since scleroderma (systemic sclerosis; SSc) is characterized by widespread microvascular injury and is frequently complicated by pulmonary fibrosis, we sought to determine the level of thrombin activity in bronchoalveolar lavage (BAL) fluid from SSc patients and normal controls. We report a significantly higher level of thrombin activity in BAL fluid from SSc patients compared with normal controls (P < 0.001). Taken together, the high levels of thrombin in BAL fluid and its demonstrated mitogenicity for lung fibroblasts suggest an important role for thrombin in the pathogenesis of SSc and perhaps other fibrotic lung diseases.

Adult↗
PubMed1994

A murine model of the eosinophilia-myalgia syndrome induced by 1,1'-ethylidenebis (L-tryptophan).

The eosinophilia-myalgia syndrome (EMS) is a recently described disease that has been associated with the ingestion of L-tryptophan containing trace amounts of several impurities. The first such contaminant to be identified and linked epidemiologically to the EMS epidemic was 1,1'-ethylidenebis(L-tryptophan) (EBT), but its role in the etiology and pathogenesis of the syndrome has been controversial. We report the development of inflammation and fibrosis affecting the dermis and subcutis, including the fascia and perimyseal tissues, after the daily intraperitoneal administration of EBT to female C57BL/6 mice. Such changes are accompanied by increased numbers of mast cells, many of which appear to be degranulating. Plasma levels of quinolinic acid, a metabolic product of L-tryptophan via the kynurenine pathway, are reduced initially, and then become elevated when inflammation and fibrosis are more pronounced. The nature and location of the inflammatory cell infiltrate and fibrosis, as well as the presence of mast cells and alterations of L-tryptophan metabolism, are consistent with findings reported in patients with EMS. This murine model suggests that EBT may have been one of the mediators of EMS and should facilitate studies of the pathogenesis of EMS.

Animals↗
PubMed1994

Limitations of panoramic radiography in the detection of bone defects in the posterior wall of the maxillary sinus: an experimental study.

Some lesions in the maxillary sinus may be adequately detected by panoramic radiography. The present study was designed to evaluate the ability of panoramic radiography in detecting experimental bony defects in the posterior wall of the maxillary sinus by comparison with Waters' projection and CT. Bony defects in the mediosuperior and medioinferior regions of the posterior wall were readily detected by panoramic radiography, but those in the laterosuperior or centre were not. It is concluded that there are limitations to the detection of bony defects in the posterior wall of the maxillary sinus by panoramic radiography alone. It is recommended that this technique should not be used for the detection of small osteolytic lesions in the maxillary sinus.

Evaluation Studies as Topic↗