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K Miyazawa

Publications and source records attributed to K Miyazawa.

At least 19 recordsLinked to original sources
PubMed1992

Functional characterization of human hepatocyte growth factor mutants obtained by deletion of structural domains.

Human hepatocyte growth factor (hHGF) consists of characteristic structural domains. In this study, we prepared mutant proteins lacking each of these domains and examined their biological activities for stimulation of hepatocyte DNA synthesis, inhibition of Meth A cell growth, and induction of MDCK cell dissociation. We also examined their interactions with the c-met/HGF receptor by competition analysis and by analysis of levels of tyrosine phosphorylation. The mutant proteins lacking the N-terminal, the first kringle, or the second kringle domain were not biologically effective and could not compete with hHGF bound to the c-met/HGF receptor. The results indicate that these domains are necessary for the biological activities of hHGF mediated by binding to the c-met/HGF receptor. The mutant proteins lacking the third or fourth kringle domain moderately retained biological activities and the receptor binding. The relative levels of the tyrosine phosphorylation of the c-met/HGF receptor by these mutant proteins correlated well with the relative potencies of the biological activities when compared with that of the wild-type hHGF. The mutant protein lacking the light chain was not effective in the biological activities and tyrosine phosphorylation of the c-met/HGF receptor, but competed with hHGF bound to the c-met/HGF receptor. These results suggest that the heavy chain plays an important role in the interaction of hHGF with the c-met/HGF receptor and that the light chain is further required for the tyrosine phosphorylation of the c-met/HGF receptor.

Amino Acid Sequence↗
PubMed1992

Activation of hepatocyte growth factor by proteolytic conversion of a single chain form to a heterodimer.

Hepatocyte growth factor (HGF) is a heterodimeric protein consisting of a heavy chain and a light chain held by a disulfide bond. These chains are produced by endoproteolytic processing from a single chain precursor. In this study, we examined whether the processing is a prerequisite for the mitogenic activity of HGF on hepatocytes in primary culture. Single chain HGF was proteolytically converted to the heterodimeric form during incubation with hepatocytes and was as mitogenic as the heterodimeric form. When the conversion was inhibited by serine-protease inhibitors, the mitogenic activity of single chain HGF was markedly reduced. Furthermore, a mutant resistant to the proteolytic processing, which was prepared by in vitro mutagenesis, completely lost the mitogenic activity. From these results, we concluded that the single chain form of HGF is endoproteolytically processed by a serine-protease and that this processing is a prerequisite for the mitogenic activity of HGF.

Amino Acid Sequence↗
PubMed1992

Recombinant human interleukin-9 induces protein tyrosine phosphorylation and synergizes with steel factor to stimulate proliferation of the human factor-dependent cell line, M07e.

Human interleukin-9 (IL-9) was originally identified and cloned based on its stimulatory effect on proliferation of human myeloid cell line, M07e. IL-9 synergized with Steel factor, the ligand for the c-kit product, to stimulate M07e cell proliferation. To investigate potential mechanisms for this, IL-9 was assessed for effects on protein tyrosine kinase activities in M07e cells by immunoblotting with anti-phosphotyrosine monoclonal antibody; results were compared with those of Steel factor alone and in combination with IL-9, and those of 12-0-tetradecanoyl phorbol-13-acetate (TPA). Recombinant human IL-9 (10 ng/mL) rapidly and transiently induced or enhanced at least four tyrosine phosphorylated protein bands with molecular weights of 105, 97, 85, and 81 Kd. This tyrosine phosphorylation pattern was different from that generated by recombinant murine Steel factor or TPA stimulation and the combination of IL-9 and Steel factor did not change the IL-9-induced pattern. IL-9-induced tyrosine phosphorylated bands were completely blocked by treatment of IL-9 with anti-IL-9 antibody under conditions that also neutralized the synergistic effect of IL-9 with Steel factor on M07e cell proliferation. Genistein, a tyrosine kinase inhibitor, blocked phosphorylation of IL-9 and Steel factor-induced bands. Unlike Steel factor or TPA, IL-9 did not appear to stimulate phosphorylation of 42-Kd mitogen-activated protein (MAP) kinase or Raf-1, or enhance MAP kinase activity. MAP kinase and Raf-1 are serine/threonine kinases that are phosphorylated and activated by many growth factors and by agonists for protein kinase C. While the combination of IL-9 plus SLF did not appear to induce phosphorylation of new bands not already seen with either IL-9 or SLF alone, or enhance the phosphorylation of those bands seen with either cytokine alone, the results suggest that IL-9 activates specific and unique signal transduction pathways.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1992

Characterization of interleukin-11 receptor and protein tyrosine phosphorylation induced by interleukin-11 in mouse 3T3-L1 cells.

In this study, we have characterized the biochemical nature of interleukin (IL)-11 receptors (IL-11R) and determined the possible signal transduction pathways mediated by IL-11 in 3T3-L1 mouse preadipocytes. The results show that IL-11 strongly inhibited lipoprotein lipase activity and adipogenesis in 3T3-L1 cells, and the suppression of lipoprotein lipase activity by IL-11 was controlled at the post-transcriptional level. The ability of IL-11 to inhibit lipoprotein lipase activity and adipogenesis therefore reflected the expression of functional IL-11R on the cell surface. Scatchard plot analysis according to specific binding data revealed the existence of a single class of high affinity IL-11R with a Kd of 3.49 x 10(-10) M and a receptor density of 5140 sites/cell on 3T3-L1 cells. Affinity cross-linking studies with 125I-IL-11 indicated that IL-11R consists of a single polypeptide chain of 151 kDa in size. Furthermore, we have studied the role of protein tyrosine phosphorylation in the IL-11R-linked signal transduction pathways. The results show that IL-11R ligation rapidly and transiently stimulated tyrosine phosphorylation of 152-, 94-, 47-, and 44-kDa proteins. This effect is specific for IL-11 since neutralizing antibody to IL-11 abrogated IL-11-induced tyrosine phosphorylation, and other cytokines such as IL-6 and IL-1 alpha did not change the tyrosine phosphorylation pattern in 3T3-L1 cells. These results suggest that IL-11R is closely linked to a functional protein-tyrosine kinase pathway, and tyrosine phosphorylation may be a key step in the initiation of the IL-11R-mediated transmembrane signaling.

3T3 Cells↗
PubMed1992

Characterization of hepatocyte-growth-factor receptors on Meth A cells.

Hepatocyte growth factor (HGF) is a heparin-binding polypeptide mitogen for a variety of cell types including hepatocytes. HGF also has cytotoxic activity on some tumor cell lines as well as scattering activity on epithelial cells. In this study, recombinant human HGF was used to identify HGF-binding cell surface receptors on Meth A cells, whose growth is inhibited by HGF. Scatchard analysis of binding data indicated that there were two classes of binding sites with high affinity (Kd = 17 pM) and low affinity (Kd = 6.7 nM) and the average numbers were 6600 and 2,600,000 per cell, respectively. Affinity cross-linking of 125I-HGF to Meth A cells resulted in a major and a minor specifically labeled complex. Competition analysis followed by cross-linking indicated that the HGF-binding proteins were involved in the formation of the high-affinity binding. The existence of the two HGF-binding surface proteins was confirmed by HGF-dependent immunoprecipitation of the binding proteins with an anti-HGF polyclonal antibody. The molecular masses of the major and the minor surface proteins were 160 kDa and 130 kDa, respectively. The 160-kDa protein was autophosphorylated in vitro on tyrosine residue and was immunoprecipitated with an antiserum against the c-met proto-oncogene product. These results indicate that the 160-kDa HGF-binding surface protein on Meth A cells is the c-met protein. Furthermore, tyrosine phosphorylation of the c-met protein was stimulated by HGF treatment of Meth A cells, suggesting that it may be involved in the signal transduction of the growth inhibition of Meth A cells by HGF.

Amino Acids↗
PubMed1992

Distribution of 5'-nucleotidase in muscle of some marine fishes.

A preliminary examination for the purification and characterization of 5'-nucleotidase of fish muscle was carried out and the following results were obtained. 1. The activities of 5'-nucleotidase in the muscles of marine vertebrates and invertebrates (total 11 species) were determined. The highest activity of 5'-nucleotidase was found in Blackrock fish Sebastes inermis, which was then used as a material for estimation of subcellular distribution and solubilization of the enzyme. 2. The 5'-nucleotidase of ordinary muscle of the fish Sebastes inermis was found in nuclear, microsomal and cytosolic fractions. About half of the total activity was found in the nuclear fraction, whereas the highest specific activity was observed in the microsomal fraction. 3. Complete solubilization of the enzyme was attained by using a high concentration of detergent such as Triton X-100, CHAPS, octylglucoside, octylthioglucoside and sodium deoxycholate, suggesting that the enzyme was tightly bound to the membrane. 4. Based on the results of solubility and stability tests, Triton X-100 seemed suitable for solubilizing 5'-nucleotidase from the membrane. 5. Microsomal 5'-nucleotidase was an Mg(2+)-activated enzyme, and no inactivation was observed up to 50 mM of Mg2+.

5'-Nucleotidase↗
PubMed1992

Technique for total abdominal hysterectomy: historical and clinical perspective.

Since the first refined total abdominal hysterectomy was performed by Wilhelm Alexander Freund of Breslau on January 30, 1878, various techniques have been introduced over the past 110 years. Hysterectomy, numbering over 650,000 procedures annually, is the most commonly performed major surgical procedure next to cesarean section in the United States. Although CREOG (Council on Resident Education in Obstetrics and Gynecology) emphasizes the importance of basic pelvic surgical skills and competency in gynecological surgical procedures, cost-effective patient management dictates the shortest hospitalization and most uncomplicated procedure possible. Various techniques of abdominal hysterectomy have been reappraised in view of present-day medical practice concepts. It seems that we are entering a new age wherein a simplified, cost-effective alternative to a classical total abdominal hysterectomy is indeed needed for some cases, and if a hysterectomy is planned, it should be performed in the safest way in the shortest possible operating time for a well-indicated case. Keeping this objective in mind, one Japanese technique of total abdominal hysterectomy and its modification are described with the intent that this will assist Ob/Gyn resident physicians in surgical skill development and also help gynecologists in practice to meet rapidly changing practice patterns of the specialty.

Female↗
PubMed1992

Hepatocyte growth factor and transforming growth factor-beta stimulate both cell growth and migration of human gastric adenocarcinoma cells.

Hepatocyte growth factor (HGF) induced scattering and cell migration of human gastric adenocarcinoma MKN-74. HGF also significantly promoted the growth of MKN-74 cells in a dose-dependent manner, although HGF is reported to be antiproliferative for the growth of tumor cell lines. This result indicates that HGF stimulates cell proliferation of not only normal epithelial cells but also certain carcinoma cells. Furthermore, transforming growth factor-beta (TGF-beta), which is recognized to inhibit the growth of most epithelial cells, additively enhanced both the cell proliferation and migration induced by HGF. These additive effects of HGF and TGF-beta may be responsible for the tumor invasiveness and uncontrolled growth of certain types of carcinoma.

Adenocarcinoma↗
PubMed1992

Experimental models of acute and chronic sialoadenitis in the guinea pig.

Acute and chronic sialoadenitis were induced in ovalbumin-immunized guinea pigs by a single or repeated (once a day for 5 days) instillation of antigen into the parotid gland via the parotid duct. The acute sialoadenitis was characterized by infiltration of inflammatory polymorphonuclear leukocytes and the chronic one, by extensive tissue destruction together with infiltration of mononuclear leukocytes. In acute sialoadenitis, myeloperoxidase activity in the parotid gland, which was a marker of accumulation of neutrophils, was elevated, but in the chronic stage, it returned nearly to the control level. This observation is in accord with the histological findings that infiltrating cells in acute and chronic sialoadenitis were mainly polymorphonuclear and mononuclear leukocytes, respectively. Although cyclophosphamide suppressed the inflammation, both in acute and chronic sialoadenitis, indomethacin exerted its anti-inflammatory effect only in the acute stage. Our experimental models of acute and chronic sialoadenitis were easy to prepare, and had a high incidence. As the typical features of inflammatory development from acute to chronic phases were observed in these models, these models may be useful for studying the mechanism of the chronic course in immunologically induced inflammation and the effects of drugs on each phase and the chronic course of inflammation.

Acute Disease↗
PubMed1992

Role of epidermal growth factor in obstetrics and gynecology.

During the past 30 years, a number of growth factors have been isolated and characterized. These include insulin and insulin-like growth factors, the fibroblast growth factors, the hematopoietic colony-stimulating growth factors, and the epidermal growth factor (EGF) group. Epidermal growth factor, which stimulates the growth of a variety of tissues, has been extensively studied since its discovery in the early 1960s. This review presents an historic perspective, basic scientific aspects, laboratory methods, and the clinical application of EGF in the specialty of obstetrics and gynecology. Expanding research on this factor together with its increasing clinical applications will undoubtedly predict its routine use in clinical practice. Understanding basic and applied knowledge of EGF will become essential for clinicians in adapting this new technology to patient care.

Amniotic Fluid↗
PubMed1991

Structural organization and the transcription initiation site of the human hepatocyte growth factor gene.

The structural organization of the gene coding for human hepatocyte growth factor (hHGF) has been determined by seven overlapping lambda phage genomic clones including three clones that were previously characterized. The gene for hHGF spans about 70 kbp of DNA and consists of 18 exons separated by 17 introns. The coding sequence of hHGF consists of multiple putative domains that are homologous to those observed in plasminogen. These regions were found as separate exons in the gene, and the exon-intron arrangement was similar to that of plasminogen. These results suggest that the genes for hHGF and plasminogen have arisen through gene duplication events from an ancestral gene. The major transcription initiation site of the hHGF gene is located 76 bp upstream of the translational start codon as judged by S1 nuclease mapping and primer extension analyses. A TATA-like element was found 33 nucleotides upstream of the transcription initiation site. Two sequence elements, an interleukin 6 response element (CTGGGA) and a potential binding site for NF-IL6 (TGAGGAAAG), are located near the transcription initiation site. These sequence elements might be involved in the regulation of HGF gene expression.

Amino Acid Sequence↗
PubMed1991

Effects of TZI-41127, a novel selective 5-lipoxygenase inhibitor, on A23187-induced pleurisy in rats.

Intrapleural injection of the ionophore A23187 in rats induced leukotriene (LT) production, prostaglandin E2 production, plasma exudation and leukocyte accumulation in the pleural cavity. We evaluated the inhibitory effects of orally administered drugs on 5-lipoxygenase activity by their ability to reduce the content of both peptido-LTs (LTC4, LTD4 and LTE4) and LTB4 in this model. TZI-41127, a novel selective 5-lipoxygenase inhibitor, significantly reduced the peptido-LTs and LTB4 content with ED50 values of 4.2 and 6.1 mg/kg, respectively, whereas it only reduced the prostaglandin E2 content (cyclooxygenase activity) by 31.1% even after 100 mg/kg. Phenidone inhibited 5-lipoxygenase activity more selectively than cyclooxygenase activity. BW755C inhibited cyclooxygenase activity more selectively than 5-lipoxygenase activity. Indomethacin selectively inhibited cyclooxygenase activity. These results suggest that: (1) A23187-induced pleurisy is an convenient in vivo model for studying drug effects on 5-lipoxygenase and cyclooxygenase activities and (2) TZI-41127 is an orally active and comparatively selective inhibitor of 5-lipoxygenase activity.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1991

An alternatively processed mRNA generated from human hepatocyte growth factor gene.

We recently reported the isolation and sequencing of cDNA for human hepatocyte growth factor (hHGF) [Miyazawa, K., Tsubouchi, H., Naka, D., Takahashi, K., Okigaki, M., Arakaki, N., Nakayama, H., Hirono, S., Sakiyama, O., Takahashi, K., Gohda, E., Daikuhara, Y. & Kitamura, N. (1989) Biochem. Biophys. Res. Commun. 163, 967-973]. In the present study, we report the sequence of another cDNA clone for a shorter form of hHGF mRNA. Comparison of the sequence with that of the hHGF cDNA revealed that the two sequences are identical in their 5' ends up to 865 nucleotides downstream from the translation-initiation site, then completely diverge from each other. By Northern blot analysis, the hHGF-related 1.5-kb mRNA, which corresponded to the newly isolated cDNA variant, was identified in human placenta. Sequence analysis of a human genomic HGF clone showed that the diverged 3'-terminal portion of the mRNA is generated by alternative RNA-processing events utilizing a specific exon. The mRNA could encode a short hHGF molecule of 290 amino acids corresponding to the N-terminal portion of hHGF which consists of 728 amino acids. In order to examine the effect of the predicted translation product on hepatocyte growth, an expression plasmid for the cDNA variant was constructed and transfected into Cos cells. Immunoblotting analysis showed that the transfected Cos cells produced a protein of about 33 kDa. The protein product did not stimulate DNA synthesis by rat hepatocytes in primary culture.

Amino Acid Sequence↗
PubMed1991

Lactoferrin-lipopolysaccharide interactions. Effect on lactoferrin binding to monocyte/macrophage-differentiated HL-60 cells.

Lactoferrin (LF) has been implicated in a number of functions including the negative regulation of myelopoiesis in vitro and in vivo, an effect mediated by suppression of cytokine release from monocytes/macrophages. This suppression is abrogated by bacterial LPS. In the present study, HL-60 cells were induced to differentiate to monocytes/macrophages by 12-O-tetradecanoyl phorbol-13-acetate, and LF-binding assays were performed. After differentiation, HL-60 cells showed a twofold increase of LF-binding sites with no difference in the specificity or affinity of LF between pre- and post-differentiated cells. CD11a, CD11b, and CD11c Ag, which have been associated with specific binding sites for LPS on monocytes/macrophages, were also increased three- to fourfold after differentiation. With the use of this system, the effect of LPS on LF binding was studied. At 37 degrees C, LPS enhanced LF binding on HL-60 cells, especially after differentiation. Conversely, at 4 degrees C, LPS inhibited LF binding. There was little effect of temperature on LF binding in the absence of LPS. In the presence of polymyxin B sulfate, the enhanced LF binding by LPS was abrogated. Also, pretreatment with mAbCD11 and/or mAb5D3, which are associated with or directed against candidate LPS receptors, reduced LF binding. Cross-linking studies using an iodinated, photoactivatable LPS derivative ([125I]ASD-LPS) demonstrated directly the specific binding of LPS to LF. These data indicate a dichotomous nature of LF binding on monocyte/macrophage-differentiated HL-60 cells--one being mediated by specific LF receptors whereas the other is apparently mainly via LPS receptors after formation of an LF-LPS complex. These interactions, for which a model is proposed, help to explain the mechanism behind LPS abrogation of the myelopoietic suppressive effects of LF, and a situation that probably occurs during bacterial infection.

Affinity Labels↗
PubMed1991

Tetrodonic acid-like substance; a possible precursor of tetrodotoxin.

A tetrodonic acid-like substance which was hardly distinguishable from authentic tetrodonic acid in thin-layer chromatography, high performance liquid chromatography, etc., was successfully purified from the ribbon worm and flatworm by a method consisting mainly of Bio-Gel P-2 column chromatography. The tetrodonic acid-like substance showed a specific toxicity of approximately 700 mouse units/mg as tetrodotoxin, unlike tetrodonic acid which is a completely non-toxic substance. Instrumental analyses including gas chromatography-mass spectrometry, secondary ion mass spectrometry and thin-layer chromatography/fast atom bombardment mass spectrometry disclosed that the tetrodonic acid-like substance had a structure similar to, but not the same as, that of tetrodotoxin. This, along with its high convertibility into tetrodotoxin during storage and other experimental operations, suggested that the tetrodonic acid-like substance is a precursor of tetrodotoxin.

Animals↗
PubMed1991

Ventricular wall motion and NE release in post-ischemic reperfused myocardium.

To clarify the relationship between post-ischemic myocardial dysfunction and local cardiac sympathetic nerve function, we measured regional myocardial length and norepinephrine (NE) release during sympathetic nerve stimulation in 32 mongrel dogs. Coronary occlusion was produced by balloon occluder for 15 min and reperfused for 60 min. Dogs were divided into 3 groups as follows; Group 1 (n = 14): Sympathetic nerve stimulation, Group 2 (n = 9): Pre-treatment with yohimbine hydrochloride (0.2 mg/kg) and sympathetic nerve stimulation, Group 3 (n = 9): Exogenous NE administration. Sympathetic nerve stimulation or NE infusion were performed before occlusion and after reperfusion. In group 1, the extent of the increase in systolic shortening during sympathetic nerve stimulation (delta - shortening) lowered at 5 min after reperfusion and augmented progressively. But, delta-shortening at an early reperfusion period did not reduce in group 2 and 3. NE release from the ischemic myocardium decreased in group 1 and did not recover for 60 min. When the cardiac sympathetic nerve was denervated with 90% phenol solution, NE release further decreased in group 1. On the other hand, NE release did not decrease in group 2. These results indicate that the response to sympathetic nerve stimulation decreased in post-ischemic reperfused myocardium and this was due to diminished NE release. It was considered that sympathetic nerve conduction was not completely impaired in post-ischemic myocardium and pre-synaptic alpha-2 receptor mediated negative feedback mechanism would play an important role in these diminished NE release.

Animals↗