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A Ichikawa

Publications and source records attributed to A Ichikawa.

At least 235 records · Page 13Linked to original sources
PubMed1991

Characterization of cytosolic pertussis toxin-sensitive GTP-binding protein in mastocytoma P-815 cells.

We have characterized a soluble pertussis toxin (PT)-sensitive GTP-binding protein (G-protein) present in mouse mastocytoma P-815 cells. 65% of total ADP-ribosylation of PT substrate having a molecular mass of 40 kDa on SDS-polyacrylamide gel electrophoresis in cell homogenate was detected in the supernatant after centrifugation at 100,000 x g for 90 min. [32P]ADP-ribosylation of cytosolic PT substrate was significantly enhanced on the addition of exogenous beta gamma complex. The molecular mass of the cytosolic PT substrate was estimated to be about 80 kDa on an Ultrogel AcA 44 column, but the beta gamma complex was not detected in the cytosol by using the anti-beta gamma complex antibody. Furthermore, the cytosolic PT substrate was found to have some unique properties: [35S]GTP gamma S binding was not inhibited by GDP and [32P]ADP-ribosylation was not affected by GTP gamma S treatment. Only after the cytosolic PT substrate had been mixed with exogenous beta gamma complex, did it copurify with exogenous beta gamma complex by several column chromatographies including an Octyl-Sepharose CL-4B column. The PT substrate was identified as Gi2 alpha by Western blot analysis and peptide mapping with S. aureus V8 protease. These results suggest that Gi2 alpha without beta gamma complex exists with an apparent molecular mass of about 80 kDa in the cytosolic fraction of P-815 cells.

Adenosine Diphosphate↗
PubMed1991

Specific binding of glycyrrhetinic acid to the rat liver membrane.

Glycyrrhetinic acid bound specifically to a particulate fraction of rat liver. The binding was dependent on time, temperature and pH, equilibrium being reached after 10 min at 37 degrees C. The equilibrium dissociation constant and the maximal concentration of the binding site, as determined by Scatchard plot analysis, were 31 nM and 43 pmol/mg protein, respectively, indicating a single binding site entity. The binding site was highly specific for glycyrrhetinic acid, glycyrrhizin, various steroids, various fatty acids and retinoids showing no or only very low affinity. The binding was inhibited by boiling or treatment with trypsin or phospholipases. The specific activity of glycyrrhetinic acid binding was the highest in the liver, followed by in the kidney. The results suggest that glycyrrhetinic acid plays a significant role in the rat liver through its specific binding protein.

Animals↗
PubMed1991

Desensitization by glycyrrhetinic acid of other stimulatory substance-induced increases in intracellular calcium in a variety of cell types.

The effects of glycyrrhizin and its aglycone, glycyrrhetinic acid, on the cytoplasmic free calcium concentration ([Ca2+]i) in mastocytoma P-815 cells, DNP-Ascaris (antigen) sensitized mast cells, hepatocytes, fibroblasts and endothelial cells were investigated. In these cell types, glycyrrhetinic acid in the concentration range of 20 to 100 microM caused an increase in [Ca2+]i and inhibited calcium increases induced by an antigen (mast cells), ATP, phenylephrine (hepatocytes) and thrombin (fibroblasts and endothelial cells). Stimulation with phenylephrine, in place of glycyrrhetinic acid, did not inhibit subsequent calcium increases induced by phenylephrine or ATP. On the other hand, glycyrrhizin at concentrations up to 100 microM neither caused an increase in [Ca2+]i nor inhibited calcium increases induced by other stimulatory substances. These results suggest that the inhibition of the calcium-mediated signal pathway may participate in the cytostatic actions of glycyrrhetinic acid.

Adenosine Triphosphate↗
PubMed1991

Differential regulation of thrombin- or ATP-induced mobilization of intracellular Ca2+ by prostacyclin receptor in mouse mastocytoma cells.

Thrombin induced an increase in [Ca2+]i in mouse mastocytoma P-815 cells. This increase was markedly reduced by prior exposure to pertussis toxin (PT) but not by removal of extracellular Ca2+, suggesting that thrombin stimulates phospholipase C via a PT-sensitive GTP-binding protein. ATP also induced an increase in [Ca2+]i. This increase was insensitive to PT but completely suppressed on removal of extracellular Ca2+, suggesting that ATP stimulates Ca2+ influx in a PT-insensitive manner. Iloprost, a stable prostacyclin analogue, increased the cellular cAMP level and dose-dependently inhibited the thrombin-induced increase in [Ca2+]i, whereas the ATP-induced increase in [Ca2+]i was markedly enhanced by iloprost. Cyclic AMP analogues, dibutyryl cAMP and 8-bromo cAMP, also inhibited the increase in [Ca2+]i induced by thrombin and promoted that by ATP, indicating that the inhibitory and stimulatory effects of iloprost are mediated by cAMP. These results suggest that the prostacyclin receptor differentially regulates two distinct Ca2+ mobilizing systems via cAMP in mastocytoma cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

The amino acid sequence of a glutamic acid-rich protein from bovine retina as deduced from the cDNA sequence.

cDNA clones encoding a glutamic acid-rich protein were isolated from a bovine retina cDNA expression library. The cDNA sequence contained an open reading frame of 1770 base pairs encoding a protein of 590 amino acids (64,509 Da) and untranslated regions of 60 and 490 base pairs at the 5' and 3' ends, respectively. The cDNA hybridized to a 2.4-kilobase retinal mRNA. The amino acid sequence derived from the cDNA sequence contains a glutamic acid-rich domain in which 68 of 109 amino acids are glutamic acid. In addition, this domain contains four repeats of a peptide of 11 amino acids and two repeats of a peptide of 26 amino acids. A polyclonal antibody raised against a decapeptide corresponding to the undecapeptide repeat sequence reacted with a protein in an extract of bovine rod outer segments, whose molecular mass, 65 kDa, corresponded to that of the above glutamic acid-rich protein. The retinal glutamic acid-rich protein showed homology with glutamic acid-rich proteins from bovine brain and the C-terminal region of mammalian neurofilaments.

Amino Acid Sequence↗
PubMed1991

Cytosol promotes the guanine nucleotide-induced release of the alpha subunit of Gi2 from the membrane of mouse mastocytoma P-815 cells.

Translocation of the alpha subunit of Gi2 from the membrane to the cytosol was studied in mouse mastocytoma P-815 cells. To monitor Gi2 alpha the membrane (300,000 x g pellet) was [32P]ADP-ribosylated with pertussis toxin. Incubation of the [32P]ADP-ribosylated membrane with guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) caused a small release (10%) of [32P]ADP-ribosylated Gi2 alpha from the membrane. Whereas cytosol (300,000 x g supernatant) alone had no ability to release the [32P]ADP-ribosylated Gi2 alpha from the membrane, it markedly augmented the release induced by GTP gamma S, about 50% of the total [32P]ADP-ribosylated Gi2 alpha being released by 30 min. The GTP gamma S-induced release and its enhancement by the cytosol were specific for GTP and GTP gamma S. When the cytosol was boiled this promoting activity was lost. The [32P]ADP-ribosylated Gi2 alpha released by the cytosol plus GTP gamma S from the membrane was eluted as a single peak corresponding to a molecular weight of about 100,000 from an Ultrogel AcA 44 column. In contrast, the [32P]ADP-ribosylated Gi2 alpha released by GTP gamma S alone was eluted at the position of Mr = 40,000, but it was eluted at the position of Mr = about 100,000 when it was incubated with the cytosol. Furthermore, Gi2 alpha purified from bovine lung also behaved in a similar way on gel filtration. The addition of thrombin, a stimulant of histamine secretion from mast cells, to mastocytoma cells drastically induced the translocation of Gi2 alpha from the membrane to the cytosol in a pertussis toxin-sensitive manner. These results taken together demonstrate that the cytosol contains some factor(s) that promotes the release of GTP-activated Gi2 alpha from the membrane and that the released Gi2 alpha exists in the cytosol as a soluble complex with unidentified component(s) in mastocytoma cells.

Adenosine Diphosphate Ribose↗
PubMed1991

Purification and characterization of nucleoside diphosphate kinase from spinach leaves.

Two types of nucleoside diphosphate kinase (NDP kinase I and NDP kinase II) have been purified from spinach leaves to electrophoretic homogeneity. The enzymes were copurified with apparent [35S]GTP-gamma S-binding activities. NDP kinase I, which was not adsorbed to a hydroxyapatite column, and NDP kinase II, which was adsorbed, had molecular weights of 16,000 and 18,000, respectively, as judged by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The molecular weights determined by gel filtration were 92,000 and 110,000, respectively, suggesting that both enzymes are composed of six identical subunits. Minor differences in some amino acids between NDP kinase I and NDP kinase II were observed when both enzymes were analyzed for amino acid composition. The apparent [35S]GTP gamma S-binding activity of purified NDP kinase I and NDP kinase II was found to be due to the formation of a [35S]thiophosphorylated enzyme, which is the intermediate of the NDP kinase reaction.

Amino Acids↗
PubMed1991

Fluctuation of fetal rat hepatic histidine decarboxylase activity through the glucocorticoid-ACTH system.

Our studies suggest that the fluctuation of HDC activity in fetal liver in late gestation is regulated by the plasma glucocorticoid level through the pituitary-adrenal system. Taken together, these results support the conclusion that glucocorticoid promotes a rapid increase in HDC synthesis in fetal liver histamine-forming cells, as well as in mouse mastocytoma P-815 cells and rat glandular stomachs.

Adrenocorticotropic Hormone↗
PubMed1991

TEI-9063, a stable and highly specific prostacyclin analogue for the prostacyclin receptor in mastocytoma P-815 cells.

The prostacyclin (PGI2) analogues, TEI-9063 and its methyl ester, TEI-1324, have been compared with another stable analogue, iloprost, with respect to binding to the PGI2 receptor, stimulation of adenylate cyclase activity and inhibition of thrombin-induced Ca2+ mobilization in mastocytoma P-815 cells. TEI-9063 displaced the [3H]iloprost binding to the membrane fraction, the IC50 value being 3 nM, but showed very low affinity for the PGE receptor. TEI-9063 dose dependently stimulated cAMP formation in the cells and GTP-dependent adenylate cyclase activity in the membrane fraction, the EC50 value being 50 and 10 nM, respectively. Furthermore, TEI-9063 prevented the thrombin-induced increase in the intracellular Ca2+ concentration, the IC50 value being 50 nM. These IC50 and EC50 values are lower than those obtained for iloprost. On the other hand, those of TEI-1324 were about two-orders higher. Although PGI2 lost its ability to stimulate cAMP formation by preincubation for 20 min at 37 degrees C, TEI-9063 completely retained its ability after 60-min preincubation. These results demonstrate that TEI-9063 is a stable and stronger agonist for the PGI2 receptor than iloprost, and that it prevents thrombin-induced Ca2+ mobilization through stimulation of the adenylate cyclase system in mastocytoma cells.

Adenylyl Cyclases↗
PubMed1991

Stimulatory effect of guanine nucleotides on prostaglandin E1 binding to murine renal outer medulla.

Prostaglandin E1 (PGE1) specifically bound to the membrane prepared from murine renal outer medulla. The extent of binding of [3H]PGE1 to the membrane was increased about 4-fold by guanosine triphosphate (GTP) and its analogs, but the dissociation of bound [3H]PGE1 from the membrane was in turn enhanced by GTP gamma S. Scatchard plot analyses revealed that GTP gamma S increased the binding affinity more than 2-fold without a major change in the number of binding sites. When [3H]PGE1-bound proteins were cross-linked in the membrane by dithiobis (succinimidyl propionate), bound [3H]PGE1 was no longer dissociated by GTP gamma S treatment, suggesting that cross-linking produced a stable complex of PGE receptor with a GTP-binding protein. The cross-linked [3H]PGE1-specifically bound proteins solubilized from the membranes labeled with [3H] PGE1 in the presence or absence of GTP gamma S were eluted as an apparently single radioactive peak at the same position of Mr = 15000 by gel filtration, indicating that the PGE receptor forms a complex with a GTP-binding protein regardless of the treatment with GTP gamma S by which [3H]PGE1 binding is promoted. The ability of GTP gamma S to stimulate [3H]PGE1 binding was eliminated by pretreatment of the membrane with pertussis toxin, but not cholera toxin, indicating that the PGE receptor is coupled to a pertussis toxin-sensitive GTP-binding protein.

Alprostadil↗
PubMed1991

Studies on the synthesis of compounds related to adenosine 3',5'-cyclic phosphate. IX. Synthesis and cytotoxic effect of adenosine 3',5'-cyclic alkylphosphoramidates.

A series of adenosine 3',5'-cyclic monophosphoramidates (3, cAMP amidates), including long-chain alkyl amidates, were synthesized from adenosine 3',5'-cyclic monophosphate (1, cAMP) by means of a one-pot reaction. This reaction proceeded by the treatment of cAMP tributylammonium salt (2) with phosphorus pentachloride (PCl5) and alkylamine in N,N-dimethylformamide (DMF). Compounds 3 synthesized were investigated to determine their cytotoxic activities on the growth of mouse mastocytoma P-815 cells, mouse mammary tumor FM3A cells, and human mammary tumor ZR-75 cells in culture. It was found that compounds 3h-m showed significant cytotoxic activities against these cell lines, and that cAMP decylamidate (3j) was the most cytotoxic compound (the concentration required for 50% inhibition of cell growth, ID50 = 6.0, 15.0, 2.2 microM, respectively); the antitumor effect on P-815 cells by a total packed cell volume method showed 81.8% inhibition. The cytotoxic activity of 3 increased with the increase in alkyl chain length up to 10 carbon atoms and decreased in compounds having longer alkyl chain.

Adenosine Monophosphate↗
PubMed1991

[Myelodysplasia predominantly involving in megakaryocytic lineage successfully treated with low-dose Ara-C].

A 17 year old male was admitted because of pancytopenia. Bone marrow aspiration revealed myelodysplasia, no increase of blast cells and excessive expansion of megakaryocytic lineage. Although mild increase of bone marrow reticulin fiber was observed, no hepatosplenomegaly was recognized. Therefore he was diagnosed as refractory anemia (RA) or MDS with myelofibrosis and treated with low dose Ara-C regimen. Remission was achieved in June 1987, but the relapse occurred in Oct. 1987. His bone marrow at the relapse showed more remarkable dysplastic change than before. Sequential bone marrow examinations thereafter, revealed an increase of megakaryocytic lineage, especially immature dysplastic megakaryocytes, leading to the appearance of the abnormal megakaryoblasts (detected with anti GP IIb/IIIa antibody) as well as uncharacterized blast cells in his terminal stage. Transformation from MDS to megakaryocytic leukemia was strongly suggested. He died of severe pneumonia in March 1989. The invasion of abnormal immature megakaryocytic cells including megakaryoblasts was observed in liver, spleen and lymph nodes at autopsy. There are several reports on cases having a common hematological features such as 1) pancytopenia in peripheral blood, 2) myelodysplasia, 3) excessive growth of megakaryocytic lineage, 4) myelofibrosis without hepatosplenomegaly, although other clinical features were different. We propose all these cases should be reviewed at the point of MDS mainly involved in megakaryocytic lineage.

Adolescent↗
PubMed1991

Cytogenetic and clonal culture evaluation after response to low dose Ara-C in myelodysplastic syndromes.

Cytogenetic and bone marrow culture studies were performed sequentially in 13 patients with myelodysplastic syndromes (MDS) who responded to low dose cytosine arabinoside (Ara-C) treatment (complete in nine and partial in four patients). Of nine patients with initial clonal karyotypic abnormalities, six recovered a normal karyotype after attaining a response to treatment, but the other three patients retained partial or total karyotypic abnormalities. A new clonal karyotypic abnormality appeared after treatment in one patient. Eight patients showed normal colony growth of both granulocyte-macrophage colony-forming units and erythroid burst-forming units after treatment, but five were still defective. There was a clear difference in the duration of response to treatment between these two groups. Consolidation treatment was not effective in patients with persistent karyotypic abnormalities or defective colony formation. Although the number of patients studied is small, these results suggest that hemopoiesis in patients with MDS following a response to treatment with low dose Ara-C is heterogeneous. Consolidation chemotherapy is recommended to ensure and prolong the response in patients showing normalization of both cytogenetic and bone marrow culture results.

Adolescent↗
PubMed1990

Interleukin 4 and gamma-interferon may play a role in the histopathogenesis of peripheral T-cell lymphoma.

The first demonstration of cytokine expression in T-cell lymphoma by immunohistochemical methods is reported. Lymph node biopsy specimens were obtained from 18 patients with peripheral T-cell lymphoma. Interleukin 4 (IL-4) and gamma-interferon were each detected in 7 lymph nodes. Lymph node specimens diagnosed as angioimmunoblastic T-cell lymphoma and angiocentric lymphoma having distinctive histopathological features expressed IL-4 more frequently than other T-cell lymphomas, and all 7 patients expressing IL-4 had hypergammaglobulinemia. Lymph nodes with gamma-interferon expression showed an increase in histiocytes and/or epithelioid cells. Thus, IL-4 may play an important role in the development of hypergammaglobulinemia as well as in the growth and histopathogenesis of T-cell lymphoma, and gamma-interferon may be responsible for the development of Lennert's lesion.

Antibodies↗
PubMed1990

cDNA-derived amino acid sequence of L-histidine decarboxylase from mouse mastocytoma P-815 cells.

The primary structure of L-histidine decarboxylase (HDC: L-histidine carboxy-lyase, EC 4.1.1.22) from mouse mastocytoma P-815 cells has been determined by parallel analysis of the amino acid sequence of the protein and the nucleotide sequence of the corresponding cDNA. HDC contains 662 amino acid residues with a molecular mass of 74017, which is larger by about 21,000 Da than that of the previously purified HDC subunit (53 kDa), suggesting that HDC might be posttranslationally processed. The HDC cDNA hybridized to a 2.7 kilobase mRNA of mastocytoma cells. Homology was found between the sequences of mouse mastocytoma HDC and fetal rat liver HDC.

Amino Acid Sequence↗
PubMed1990

Effect of tunicamycin on functions of PGE1 receptors from mouse mastocytoma P-815 cells.

Prostaglandin E1 (PGE1) receptors from mouse mastocytoma P-815 cells were found to bind to a wheat germ agglutinin (WGA)-Agarose column, suggesting that the receptors are glycoproteins. To further elucidate the role of carbohydrate moieties in the PGE1 receptors for their binding activity to ligand, the P-815 cells were treated with tunicamycin, swainsonine or monensin. Tunicamycin, an inhibitor of N-glycosylation, dose- and time-dependently inhibited the binding of PGE1 to mastocytoma P-815 cells. Neither swainsonine, an inhibitor of Golgi mannosidase II, nor monensin, an inhibitor of processing beyond the high mannose stage, altered PGE1 binding properties of the cells. The inhibition of PGE1 binding by tunicamycin was observed when incorporation of [3H]glucosamine into macromolecules was inhibited. The inhibitory effect was not on their affinity but on their number of binding sites. Subcellular distributions of [3H]PGE1-binding activity showed that decreases in the binding activity by tunicamycin were highest in plasma membrane fractions. Treatment of membranes with various endo- and exoglycosidases did not affect PGE1 binding. PGE1-stimulated cyclic AMP accumulation in the cells was also inhibited by tunicamycin. These results suggest that PGE1 receptors of mastocytoma P-815 cells are glycoproteins and that inhibition of N-glycosylation of PGE1 receptors by tunicamycin results in the arrest of the translocation of newly synthesized receptors to the surface of mastocytoma P-815 cells.

Alkaloids↗