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S Okabe

Publications and source records attributed to S Okabe.

At least 37 records · Page 2Linked to original sources
PubMed2001

Rapid redistribution of the postsynaptic density protein PSD-Zip45 (Homer 1c) and its differential regulation by NMDA receptors and calcium channels.

PSD-Zip45 (Homer 1c) and PSD-95 are postsynaptic density (PSD) proteins containing distinct protein-interacting motifs. Green fluorescent protein (GFP)-tagged PSD-Zip45 and PSD-95 molecules were targeted to the PSD in hippocampal neurons. We analyzed dynamic behavior of these GFP-tagged PSD proteins by using time-lapse confocal microscopy. In contrast to the less dynamic properties of PSD-95, PSD-Zip45 showed rapid redistribution and a higher steady-state turnover rate. Differential stimulation protocols were found to alter the direction of PSD-Zip45 assembly-disassembly. Transient increases in intracellular Ca(2+) by voltage-dependent Ca(2+) channel activation induced PSD-Zip45 clustering. In contrast, NMDA receptor-dependent Ca(2+) influx resulted in the disassembly of PSD-Zip45 clusters. Thus, neuronal activity differentially redistributes a specific subset of PSD proteins, which are important for localization of both surface receptors and intracellular signaling complexes.

Animals↗
PubMed2001

A new functional domain of Bcl6 family that recruits histone deacetylases.

The proto-oncogene Bcl6 and its family gene, BAZF, encode a sequence-specific transcriptional repressor which contains the BTB/POZ domain in NH(2)-terminal region and zinc finger motifs in COOH-terminal region. The BTB/POZ domain and the middle portion of Bcl6 and BAZF are known to display transrepressor activity. Since we have identified the identical 17-amino acid (aa) sequence in the middle portion of Bcl6 and BAZF, the 17aa region may be another repressive domain of the middle portion. The reporter gene assay indicates that the 27aa sequence including the 17aa region recruits histone deacetylases to express transrepressor activity. Furthermore, overexpression of Bcl6 or Bcl6(POZ-) (Bcl6 deleted with the BTB/POZ domain) induced apoptosis in NIH3T3 cells, and the apoptosis was inhibited by the addition of histone deacetylase inhibitor in the culture. However, apoptosis was not induced in NIH3T3 cells by overexpression of Bcl6(POZ-) deleted with the 17aa region. These results indicate that the 17aa region in the middle portion of Bcl6 is a functional domain of transrepressor activity and is responsible for inducibility of apoptosis in NIH3T3 cells.

3T3 Cells↗
PubMed2001

Cancer prevention with green tea and monitoring by a new biomarker, hnRNP B1.

The study of green tea polyphenols as a cancer preventative is approaching a new era, with significant results accumulating rapidly. This paper briefly reviews four topics related to mechanisms of action of tea polyphenols: (I) identification of the genes commonly affected by EGCG, as demonstrated by Clontech's Atlas cDNA Expression Array; (II) the significance of heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1) as a new biomarker for early detection of lung cancer, and inhibition of its expression by EGCG; (III) the synergistic or additive effects of EGCG with the cancer preventive agents, sulindac and tamoxifen, on induction of apoptosis in PC-9 cells and on inhibition of intestinal tumor development in multiple intestinal neoplasia (Min) mice; (IV) the results of a 10 year prospective cohort study demonstrating the effectiveness of daily consumption of green tea in preventing cancer, and a prototype study for developing green tea beverage as cancer preventive.

Animals↗
PubMed2001

Helicobacter pylori membrane protein 1: a new carcinogenic factor of Helicobacter pylori.

Considering a suspected link between Helicobacter pylori infection and human stomach cancer, a new H. pylori gene for membrane protein 1 (HP-MP1) was recently cloned. Because HP-MP1 induces release of inflammatory cytokines and tumor necrosis factor-alpha acts as both initiator and tumor promoter, we studied the possible involvement of HP-MP1 in carcinogenesis of H. pylori. Two cell lines, BALB/3T3 cells as control and v-Ha-ras-transfected BALB/3T3 cells (Bhas 42 cells) as putative initiated cells, were each transfected with HP-MP1, urease B genes, or vector alone. All of the Bhas/mpl clones showed strong expression of tumor necrosis factor-alpha gene and produced tumors in 100% of nude mice. Two Bhas/ure clones showed weak tumorigenicity; the other Bhas and BALB clones showed none. Results indicate strong carcinogenic activity of HP-MP1 in cooperation with viral Ras protein and weak activity of urease B.

3T3 Cells↗
PubMed2001

Spine formation and correlated assembly of presynaptic and postsynaptic molecules.

Hippocampal pyramidal neurons in culture showed a developmental shift in synapse distribution from dendritic shafts to spines. Using dual wavelength time-lapse fluorescence microscopy, we analyzed the morphogenesis of three synaptic components: dendritic spines, postsynaptic densities (PSDs), and presynaptic vesicles. Local assembly of a major PSD protein, PSD-95, was spatially and temporally correlated with spine morphogenesis. Clustering of postsynaptic PSD-95 and that of a predominant synaptic vesicle protein, synaptophysin, were also correlated. In contrast, pre-existing PSD-95 clusters in dendritic shafts were preferentially eliminated without promoting spine formation. The local and stepwise assembly of synaptic components at the contact sites between dendritic protrusions and axons explains the developmental remodeling of excitatory synapses.

Adenoviridae↗
PubMed2001

Mechanism for Helicobacter pylori stimulation of interleukin-8 production in a gastric epithelial cell line (MKN 28): roles of mitogen-activated protein kinase and interleukin-1beta.

Although it is known that the pathogenic mechanism of Helicobacter pylori involves the stimulated production of interleukin-8 (IL-8) as an inflammatory mediator, the details of the pathway remain unclear. The role of mitogen-activated protein kinase (MAPK) in IL-8 production by H. pylori has been examined in an in vitro study. IL-8 mRNA expression in gastric epithelial cells (MKN 28) was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). IL-8 production was examined by ELISA. The activation of p38 MAPK was assessed by western blotting. Neither IL-8 mRNA nor activated p38 MAPK or p44/42 MAPK was detected in cells not treated with H. pylori. In contrast, incubation of cells with H. pylori, or IL-1beta, or both, clearly stimulated the expression of IL-8 mRNA within 60 min in a concentration-dependent manner. Phosphorylation of p38 MAPK and p44/p42 MAPK, as well as IL-8 production, occurred within 30 min and 24 hr after co-culturing MKN 28 cells with H. pylori and IL-1beta, respectively. Pretreatment of cells with MAPK inhibitors [1-[7-(4-fluorophenyl)-1,2,3,4-tetra-hydro-8-pyridylpyrazolo[5,1-c][1,2,4]triazin-2-yl]-2-phenylethanedione sulfate monohydrate (FR167653), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB203580), or 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one (PD98059)] significantly inhibited IL-8 production stimulated by H. pylori or IL-1beta or both. The combination of H. pylori and IL-1beta additively stimulated IL-8 production. The additive effect of H. pylori and IL-1beta on IL-8 production was inhibited by treatment with a p38 MAPK inhibitor. It was revealed that the culturing of MKN 28 cells with H. pylori significantly stimulates IL-8 production to a degree sufficient for induction of neutrophil chemotaxis via activation of p38 and p44/42 MAPK.

Activating Transcription Factor 2↗
PubMed2001

Binding of BAZF and Bc16 to STAT6-binding DNA sequences.

BAZF, a family member of Bcl6, can function as a sequence-specific transcriptional repressor. We determined BAZF-binding DNA sequence. The consensus binding sequence (CBS) of BAZF is almost the same as those of Bcl6 previously described. Three nucleotides of T, G and A at position 6, 8, and 9 in the CBS (5'-ATTCCTAGAAAG-3') are important nucleotides for binding of both BAZF and Bcl6. Since a part (5'-TTC-CTA-GAA-3') of the CBS resembled the sequence motif (5'-TTC-(N3-4)-GAA-3') bound by STAT factors, BAZF and Bcl6 can bind to the CD23b-STAT6-binding sequence (5'-TTTC-TTA-GAAAT-3'), the immunoglobulin germline epsilon-STAT6-binding sequence (5'-CTTC-CCAA-GAAC-3'), and the IL4-STAT6-binding sequence (5'-TTTC-CCA-GAAAA-3') with weak affinity. However, a mutation of C nucleotide to T nucleotide in the IL4-STAT6-binding sequence (5'-TTTC-CTA-GAAAA-3') strongly increased the binding activity of BAZF and Bcl6. These results suggest that BAZF and Bcl6 can repress some of STAT-induced transcription by binding to DNA sequences recognized by STAT factors.

Animals↗
PubMed2001

Combination cancer chemoprevention with green tea extract and sulindac shown in intestinal tumor formation in Min mice.

Green tea is the most effective beverage for cancer prevention in humans. Looking at the concept of combination cancer chemoprevention, we previously reported the synergistic effects of (-)-epigallocatechin gallate (EGCG) with sulindac, and the additive effects of EGCG with tamoxifen, on cancer-preventive activity in human lung cancer cell line PC-9. This paper reports confirmation of the synergistic effects of EGCG with sulindac on the inhibition of intestinal tumors in multiple intestinal neoplasia (Min) mice. Treatment with both green tea extract and sulindac significantly reduced the number of tumors from 72.3 +/- 28.3 to 32.0 +/- 18.7 tumors per mouse, a decrease of 44.3%, whereas treatment with green tea extract alone or with sulindac alone reduced it to 56.7 +/- 3.5 and 49.0 +/- 12.7, respectively. The results also indicated that green tea extract inhibited tumor growth in Min mice almost as potently as sulindac itself did. The three treated groups did not show any adenocarcinomas, whereas 10.8% of the control group did. Since cancer-preventive agents like sulindac and tamoxifen are associated with adverse effects, we discuss the possibility of non-toxic, combination cancer chemoprevention with green tea, looking at the goal of truly effective cancer prevention.

Adenocarcinoma↗
PubMed2001

Visualizing synapse formation and remodeling: recent advances in real-time imaging of CNS synapses.

The formation and maintenance of synaptic connections are critical in the development and plasticity of the central nervous system (CNS). Until recently, there have been few studies that followed the molecular sequences of the CNS synapse formation and maintenance. This situation changed dramatically after the introduction of green fluorescent protein (GFP)-based fluorescent probes and the development of lipophilic tracers of endocytotic membranes. These techniques enabled us to visualize presynaptic and postsynaptic structures in living neurons and illustrated active transport and remodeling of synaptic components. Furthermore, recent attempts to identify correlation between presynaptic and postsynaptic morphogenesis suggested very rapid time course of synapse formation at the individual axo-dendritic contact sites. These recent works clearly demonstrated the power of real-time imaging studies. Development of a wide variety of fluorescent probes and advances in the imaging techniques in future will further extend our knowledge on the molecular events that take place in the process of the development and maturation of synaptic junctions.

Animals↗
PubMed2001

Interhemispheric interaction between the hand motor areas in patients with cortical myoclonus.

OBJECTIVE: To study interhemispheric interaction between the hand motor areas of both hemispheres through the corpus callosum in myoclonus epilepsy. SUBJECTS: Five patients with benign myoclonus epilepsy and ten age matched normal volunteers. METHODS: We studied effects of a medially directed conditioning stimulus over the right hand motor area on responses in the right first dorsal interosseous muscle to a posteriorly directed test stimulus over the left hand motor area. RESULTS: In normal subjects, inhibition was evoked at interstimulus intervals (ISIs) of 8-20ms (late inhibition). In contrast, facilitation occurred in patients at ISIs of 4-6ms (early facilitation) with no late inhibition. CONCLUSIONS: The lack of late inhibition in the patients is consistent with the idea that cortical inhibitory interneurones are affected in myoclonus epilepsy. We propose that this releases interhemispheric facilitation from powerful surround inhibition. The consequence is a predominant early facilitation between the hemispheres in patients with myoclonus epilepsy.

Corpus Callosum↗
PubMed2001

gamma-Hydroxybutyric acid and 5-fluorouracil, metabolites of UFT, inhibit the angiogenesis induced by vascular endothelial growth factor.

UFT, a drug composed of uracil and tegafur at the molar ratio of 4:1, is an orally active agent for the treatment of a wide variety of malignant tumours. Using a murine dorsal air sac (DAS) assay, we have previously shown that UFT and its metabolites, gamma-hydroxybutyric acid (GHB) and 5-fluorouracil (5-FU), inhibited the angiogenesis induced by murine renal cell carcinoma. Here we report that UFT was more effective than other fluorinated pyrimidines such as 5-FU and doxifluridine (5'-DFUR) in blocking the angiogenic responses elicited by five human cancer cell lines which produced high levels of vascular endothelial growth factor (VEGF), but no detectable fibroblast growth factor-2 (FGF-2) in vitro. In contrast, UFT was unable to block the angiogenic response to one human gastric cancer cell line which produced both VEGF and FGF-2 in vitro. However, the production or secretion of VEGF by these cells was unaffected by GHB and 5-FU treatment. Interestingly, GHB suppressed the chemotactic migration and tube formation of human umbilical vein endothelial cells (HUVECs) stimulated by VEGF, without inhibiting their DNA synthesis. Since GHB did not affect the FGF-2-driven activities in HUVECs, its action appears to be VEGF-selective. On the other hand, 5-FU inhibited DNA synthesis and migration of HUVECs stimulated by both VEGF and FGF-2, and tube formation driven by VEGF, suggesting that 5-FU is cytotoxic to endothelial cells. The inhibitory effects of 5-FU, and especially those GHB, were reproduced under in vivo condition using the DAS assay. The VEGF-mediated angiogenesis was significantly inhibited by UFT, 5-FU, and especially by GHB. We propose that the selective inhibitory effects of GHB on VEGF-mediated responses of endothelial cells are involved in the anti-angiogenic activity of UFT.

Angiogenesis Inhibitors↗
PubMed2001

A new function of green tea: prevention of lifestyle-related diseases.

In the normal human life span, there occur lifestyle-related diseases that may be preventable with nontoxic agents. This paper deals with the preventive activity of green tea in some lifestyle-related diseases. Green tea is one of the most practical cancer preventives, as we have shown in various in vitro and in vivo experiments, along with epidemiological studies. Among various biological effects of green tea, we have focused on its inhibitory effect on TNF-alpha gene expression mediated through inhibition of NF-kappaB and AP-1 activation. Based on our recent results with TNF-alpha-deficient mice, TNF-alpha is an endogenous tumor promoter. TNF-alpha is also known to be a central mediator in chronic inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. We therefore hypothesized that green tea might be a preventive agent for chronic inflammatory diseases. To test this hypothesis, TNF-alpha transgenic mice, which overexpress TNF-alpha only in the lungs, were examined. The TNF-alpha transgenic mouse is an animal model of human idiopathic pulmonary fibrosis which also frequently develops lung cancer. Expressions of TNF-alpha and IL-6 were inhibited in the lungs of these mice after treatment with green tea in drinking water for 4 months. In addition, judging from the results of a prospective cohort study in Saitama Prefecture, Japan, green tea helps to prevent cardiovascular disease. In this study, a decreased relative risk of death from cardiovascular disease was found for people consuming over 10 cups of green tea a day, and green tea also had life-prolonging effects on cumulative survival. These data suggest that green tea has preventive effects on both chronic inflammatory diseases and lifestyle-related diseases (including cardiovascular disease and cancer), resulting in prolongation of life span.

Animals↗
PubMed2001

Role of GABA within the nucleus tractus solitarii in the hypoxic ventilatory decline of awake rats.

The purpose of this study was to examine our hypothesis that gamma-aminobutyric acid (GABA) in the nucleus tractus solitarii (NTS) may be related to the hypoxic ventilatory decline (HVD) and that chemoreceptor stimulation was essential to activate this mechanism. We used unanesthetized, freely moving rats in this study. An in vivo microdialysis technique was used to measure the extracellular GABA concentration ([GABA]o), and an in vivo microinjection technique was used to examine the effects of the GABA agonists and antagonists on the ventilation during hypoxia. The GABA agonists injected into the NTS attenuated the ventilation during hypoxia. By hypoxic exposure, [GABA]o was increased during the HVD. However, by carotid body denervation (CBD), this GABA increase was abolished. Although GABA antagonists microinjected into the NTS during the HVD phase significantly increased the depressed ventilation, this effect on the ventilation was abolished by CBD. These results suggest that the GABA in the NTS has a pivotal role in the HVD and that this mechanism is not activated without chemoreceptor stimulation.

Animals↗
PubMed2001

Recent advances in gastrointestinal pathophysiology: role of heat shock proteins in mucosal defense and ulcer healing.

The defense mechanism of the gastrointestinal mucosa against aggressive factors, such as hydrochloric acid, bile acid and non-steroidal anti-inflammatory drugs, mainly consists of functional, humoral and neuronal factors. Mucus-alkaline secretion, mucosal microcirculation, and motility act as functional factors, while prostaglandins and nitric oxide act as humoral factors, and capsaicin sensitive sensory neurons act as neuronal factors. All the above factors are known to contribute to mucosal protection. In recent years, heat shock proteins (HSPs), to include HSP70, have been implicated to be an additional factor utilized for the defense mechanisms of the gastrointestinal mucosa at the intracellular level. The expression of HSP70 and HSP47 markedly changes during the development and healing of chronic gastric ulcers in rats. It was revealed that HSC70 (a constitutive form of HSP70) is coprecipitated with cyclooxygenase-1 and the neuronal form of nitric oxide synthase after treatment with a mild irritant (20% ethanol). A positive relationship between enhanced interaction of HSC70 with either cyclooxygenase-1 or nitric oxide synthase and mucosal protection against a strong irritant (100% ethanol) was observed. It was concluded that HSPs might contribute to mucosal defense mechanisms and ulcer healing, most probably through protecting key enzymes related to cytoprotection.

Animals↗
PubMed2001

New TNF-alpha releasing inhibitors, geraniin and corilagin, in leaves of Acer nikoense, Megusurino-ki.

The success of green tea as a cancer preventive is based on evidence that green tea contains tannins and antioxidants, does not show toxicity in humans and has long traditional use in Asia. In the light of this, herbal medicines are now also attracting attention as potential sources of cancer preventive agents. Using the inhibition of TNF-alpha release assay, we studied Acer nikoense (Megusurino-ki in Japanese), one of the herbal medicines. The inhibitory activity of TNF-alpha release was found in the leaf extract rather than the bark extract, and the main active constituents were identified as geraniin and corilagin, which are present in another Japanese traditional herb, Geranium thunbergii (Genno-shoko). The IC50 values of TNF-alpha release inhibition were 43 microM for geraniin and 76 microM for corilagin, whereas that for (-)-epigallocatechin gallate (EGCG) was 26 microM. Treatment with geraniin prior to application of okadaic acid, a tumor promoter on mouse skin initiated with 7,12-dimethylbenz(a)anthracene, reduced the percentage of tumor-bearing mice from 80.0 to 40.0% and the average numbers of tumor per mouse from 3.8 to 1.1 in week 20. Thus, geraniin has slightly weaker inhibitory activity than EGCG. Since geraniin and corilagin have been well investigated as representative tannins, we discuss here the new possibility of classical herbal medicine in the development of preventive agents for cancer and other life-style related diseases.

3T3 Cells↗
PubMed2001

Modulation of gene expression by (-)-epigallocatechin gallate in PC-9 cells using a cDNA expression array.

Green tea is the most effective cancer preventive beverage. In the light of this, the mechanisms of action of tea polyphenols were investigated on the molecular levels. We present here the effects of (-)-epigallocatechin gallate (EGCG) on expression of 588 genes in human lung cancer cell line PC-9 cells, using a human cancer cDNA expression array. The levels of gene expression in non-treated control cells, and cells treated with EGCG alone, with the tumor promoter okadaic acid alone, and with EGCG plus okadaic acid, were studied, and their expression levels were classified into down-regulation (under 0.5 fold) and up-regulation (over 2.0 fold) by comparing with the levels of control. Non-treated PC-9 cells expressed 163 genes out of 588, and EGCG-treated cells induced down-regulated expression of 12 genes and up-regulated expression of 4 other genes. From a comparison of gene expression in the cells treated with EGCG and in cells treated with EGCG plus okadaic acid, we found the following genes commonly affected by EGCG: down-regulation of four genes, NF-kappaB inducing kinase (NIK), death-associated protein kinase 1 (DAPK 1), rhoB and tyrosine-protein kinase (SKY); up-regulation of one gene, retinoic acid receptor alpha1. Among them, we think down-regulation of NIK gene expression is significant for cancer prevention, based on evidence that inhibition of NF-kappaB activation is a result of inhibition of NIK/IKK signalling complex.

Antimutagenic Agents↗
PubMed2001

[Pharmacological study on the pathological changes of the gastric mucosa in Helicobacter pylori-infected Mongolian gerbils].

Helicobacter pylori (H. pylori) infection has been recognized to be a causal factor of gastritis, ulcers and gastric cancer in man. Using Mongolian gerbils (M. gerbils), which are suitable for an H. pylori infection animal model, we examined 1) how H. pylori infection, indomethacin and their combination affects the healing of gastric ulcers and whether or not such factors provoke a relapse of healed acetic acid ulcers; and 2) whether or not eradication of the bacteria with drugs at specified times after infection prevents the development of mucosal changes, including gastric adenocarcinoma. 1) H. pylori infection significantly delayed ulcer healing 4 weeks following infection. Indomethacin treatment showed a tendency to delay ulcer healing. Ulcer healing in H. pylori-infected M. gerbils was significantly delayed by indomethacin. H. pylori infection resulted in a relapse of healed ulcers from 1 to 6 months after infection, with a gradual increase in size. Omeprazole markedly prevented the ulcer relapse caused by H. pylori infection. 2) Four or 8 months after H. pylori inoculation, eradication was performed by concurrent treatment with omeprazole + clarithromycin. Immediately after treatment ended in both the 5 and 9 month groups, it was verified that H. pylori were completely eradicated. Autopsy performed 18 months after H. pylori inoculation revealed gastric hyperplastic polyps with erosive lesions and ulcers that were grossly visible; and atrophic gastritis, intestinal metaplasia, carcinoids, and adenocarcinomas were histologically observed in the non-treated control group. In animals eradicated after 4 months and autopsied after 18 months, however, such mucosal changes were not observed. In contrast, intestinal metaplasia and mucosal atrophy was observed in animals eradicated after 8 months and autopsied after 18 months. It was concluded that 1) H. pylori infection delayed the healing of preexisting gastric ulcers and resulted in the relapse of healed ulcers, yet indomethacin had little or no effect on ulcer healing or relapse; and 2) early eradication of H. pylori infection with drug therapy can prevent severe gastric mucosal changes, to include adenocarcinomas, in M gerbils.

Adenocarcinoma↗