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S Yamashiro

Publications and source records attributed to S Yamashiro.

At least 91 records · Page 5Linked to original sources
PubMed1995

Characterization of the COOH terminus of non-muscle caldesmon mutants lacking mitosis-specific phosphorylation sites.

Phosphorylation of rat non-muscle caldesmon by cdc2 kinase causes reduction in most of caldesmon's properties, including caldesmon's binding to actin, myosin, and calmodulin, as well as its inhibition of actomyosin ATPase. We have generated and characterized the COOH terminus of caldesmon mutants lacking mitosis-specific phosphorylation sites, because the COOH-terminal half of caldesmon contains all 7 putative Ser or Thr sites for cdc2 kinase. Codons for the 7 putative Ser or Thr residues have been mutated to Ala, and resultant mutants were bacterially expressed. Analyses of the phosphopeptide maps of these mutants have identified 6 sites, including Ser-249, Ser-462, Thr-468, Ser-491, Ser-497, and Ser-527 as the mitosis-specific phosphorylation sites, whereas the phosphorylation of the remaining site, Thr-377, is not detected by this assay method. Actin binding experiments have suggested that 5 sites including Ser-249, Ser-462, Thr-468, Ser-491, and Ser-497 are important for the phosphorylation-dependent reduction in actin binding. Characterization of a mutant lacking all 7 Ser or Thr sites (7-fold mutant) has revealed that 7-fold mutation eliminates all phosphorylation sites by cdc2 kinase. While the in vitro properties of the 7-fold mutant, including actin, myosin, and calmodulin binding and inhibition of actomyosin ATPase, are very similar to those of nonmutated protein, such properties are not affected by the treatment with cdc2 kinase in contrast to nonmutated protein. This mutant should thus be useful to explore the functions of the mitosis-specific phosphorylation of caldesmon.

Amino Acid Sequence↗
PubMed1995

T cell receptor-mediated stimulation of mouse thymocytes induces up-regulation of the GM2/GD2 synthase gene.

cDNA clones of the mouse GM2/GD2 synthase (EC 2.4.1.92) gene were isolated, and their analyses revealed that the protein has a type II transmembrane structure with 533 amino acids, which was very similar to the human homolog except for the mRNA size. The mRNA level in thymocytes dramatically increased after treatment with anti-CD3 monoclonal antibody, whereas it was not elevated when treated with prostaglandin E2. In situ hybridization showed an elevation of mRNA levels in medullar thymocytes, suggesting that T cell receptor-mediated signaling induces up-regulation of the GM2/GD2 synthase gene in mature thymocytes.

Amino Acid Sequence↗
PubMed1995

Expression of alpha 2,8-sialyltransferase (GD3 synthase) gene in human cancer cell lines: high level expression in melanomas and up-regulation in activated T lymphocytes.

GD3 Synthase (alpha 2,8sialyltransferase) (EC 2.4.99.8) cDNA has been cloned by eukaryotic cell expression cloning. Using this cDNA as a probe, the expression level of the gene in human cancer cell lines was analysed by Northern blotting and RT-PCR, then correlated with the ganglioside expression and enzyme activity. Melanoma cell lines showed extremely strong bands in Northern blot and RT-PCR/Southern analysis. The enzyme activity was also very high in melanomas as expected. Neuroblastoma and astrocytoma lines showed relatively low levels of the gene expression, whereas they expressed high levels of GD2. Although the mRNA level of the GD3 synthase gene and enzyme activity in individual cell lines correlated positively, some cell lines showed much higher activity than expected from the mRNA level. Among leukaemia lines, adult T cell leukaemia-associated (HTLV-I+) lines showed fairly high levels of the mRNA. On the other hand, T-ALL lines showed very low levels. In addition, GD3 and GD2 expression and mRNA level of the gene during T lymphocyte activation were analysed. Only GD3 expression was induced by any of the stimulatory reagents used, and corresponding up-regulation of the GD3 synthase gene was shown in RT-PCR/Southern analysis.

Base Sequence↗
PubMed1995

Diverse expression of beta 1,4-N-acetylgalactosaminyltransferase gene in the adult mouse brain.

Among various tissues of mouse, beta 1,4-N-acetylgalactosaminyltransferase (GM2/GD2 synthase) gene is expressed predominantly in the brain. Further analysis of the gene expression in the mouse CNS was performed by northern blotting and by enzyme assays using extracts from various parts of the CNS. In situ hybridization was also done to investigate the distribution of cells generating GM2/GD2 synthase. In northern blots, diverse levels of the gene expression were observed, depending on the regions examined. By in situ hybridization, pyramidal cells in the hippocampus, granular cells in dentate gyrus and cerebral cortex, Purkinje cells in cerebellum, and mitral cells in the olfactory bulb expressed high levels of the mRNA; these results corresponded to the results obtained by northern blot. Enzyme levels in these sites were accordingly high. However, enzyme levels in certain areas with low mRNA intensities, such as thalamus and pons medulla, were higher than expected from the results of northern blotting. The significance of the high gene expression in certain areas for brain function and the reason for the discrepancy between mRNA level and enzyme activity in some regions are discussed.

Animals↗
PubMed1995

Partial complementary deoxyribonucleic acid cloning of equine relaxin messenger ribonucleic acid, and its localization within the equine placenta.

To determine the site of relaxin gene expression in equine placentae, a set of degenerate oligonucleotide primers was made according to the published amino acid sequence of the A- and B-chain of equine relaxin (eRXN). Total cellular RNA (tcRNA) from equine placentae at about 120 and 300 days of pregnancy was subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) with use of these primers. A single amplification product of approximately 430 bp was detected in each case by agarose gel electrophoresis. The PCR product was ligated into Bluescript plasmid and sequenced to confirm the identity of the clone as an eRXN cDNA fragment. Nucleic acid sequence analysis revealed a 428-bp eRXN cDNA fragment encoding for parts of the A- and B-chain and the connecting peptide (109 residues). Northern analysis of tcRNA from placentae of 120 and 300 days of pregnancy was carried out with use of antisense digoxigenin-labeled cRNA generated from the cDNA clone, and a single transcript of approximately 1 kb was detected. In situ hybridization on placental tissue at 120 and uteroplacental tissue at 300 days of pregnancy indicated that only the fetal trophoblastic cells expressed eRXN mRNA transcripts. The identity of these cells was confirmed by their positive staining with an antibody specific for equine trophoblast (cell surface) protein. Relaxin peptide was also detected immunohistochemically in samples of the same placental tissues. This is the first report of the nucleic acid sequence of eRXN. The study identified fetal trophoblast cells as the site of eRXN mRNA expression and protein secretion in the equine placenta.

Amino Acid Sequence↗
PubMed1995

Immunophenotypic and immunoelectron microscopic characterization of major constituent cells in malignant fibrous histiocytoma using human cell lines and their transplanted tumors in immunodeficient mice.

BACKGROUND: Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of adult life. Its histogenesis, however, is still a matter of debate because of its various cellular components. EXPERIMENTAL DESIGN: To elucidate the nature of tumor cells of MFH, six human MFH cell lines were compared immunohistochemically and immunoelectron microscopically with fibrosarcoma and fibroblast cell lines. In vitro differentiation of tumor cells was evaluated after the treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA), IL-3, macrophage CSF, and granulocyte-macrophage CSF. Heterotransplantation of MFH tumor cells into nude mice and severe combined immunodeficient mice was performed to examine whether the tumor cells differentiate toward histiocytes or not. Gene expression of monocyte chemoattractant protein-1 in cultured tumor cells and transplanted tumors was also evaluated. RESULTS: All MFH cell lines examined were positive for collagen type I and prolyl hydroxylase. They failed to react with most anti-myeloid mAb such as CD11c, CD14, CD15, CD33, CD35, CD45, anti-HLA-DR, and PM-2K. Several Ab, including CD13, CD32, CD68, CD71, and HAM56, were reactive with MFH cells. However, all of these Ab were also reactive with fibrosarcoma and/or fibroblastic cell lines. These data indicate that MFH cell lines possess immunophenotypic characteristics very similar to those of fibrosarcoma and fibroblastic cell lines. In vitro treatment of tumor cells with TPA, IL-3, macrophage CSF, granulocyte-macrophage CSF, or their combination did not change their immunophenotypic characteristics and did not induce differentiation toward histiocytes (macrophages). Transplantation of tumor cells into nude mice and severe combined immunodeficient mice produced tumors similar in histology to human MFH. Tumor cells in the transplanted tumors revealed the same immunophenotypic characterization that they did in vitro. No in vivo differentiation of tumor cells toward histiocytes was observed. Immunohistochemical staining with anti-mouse macrophage mAb revealed marked infiltration of macrophages of mouse origin. Quantitative immunoelectron microscopy disclosed that these cells coincided with histiocyte-like cells. Gene expression of monocyte chemoattractant protein-1 was detected in all MFH cell lines as well as in transplanted tumors. CONCLUSIONS: The histiocyte-like cells in malignant fibrous histiocytoma are not a neoplastic component but rather infiltrated macrophages attracted by tumor-derived monocyte chemoattractant(s), and the tumor cells belong to a fibroblastic lineage differentiated from mesenchymal cells.

Adult↗
PubMed1994

Isolation of GD3 synthase gene by expression cloning of GM3 alpha-2,8-sialyltransferase cDNA using anti-GD2 monoclonal antibody.

For the isolation of ganglioside GD3 synthase (EC 2.4.99.8) cDNA, we developed an expression cloning approach that used an anti-GD2 monoclonal antibody for selection. A host recipient cell line that we have named KF3027-Hyg5 was also utilized. This cell line expresses high levels of GM2 as well as GM3 but no GD3 or GD2 and was constructed from mouse B16 melanoma cells transfected with the polyoma large tumor antigen gene (KF3027) and the previously cloned beta-1,4-N-acetylgalactosaminyltransferase (EC 2.4.1.92) cDNA. Four rounds of transfection, monoclonal antibody 3F8 panning, and Hirt extraction resulted in the isolation of two cDNA clones, transfection of which directed the expression of GD3 in KF3027 and B16 melanoma cells and GD3 and GD2 in KF3027-Hyg5 cells. The cDNA contained a 1650-bp insert and a single open reading frame. The deduced amino acid predicted a type II membrane topology consisting of cytoplasmic (14 aa), transmembrane (18 aa), and catalytic (309 aa) domains. The sequence also predicted the presence of a sialyl motif similar to that found in the other sialyltransferases cloned so far. As expected, mRNA of this gene (2.6 kb) was strongly expressed in human melanoma lines.

Amino Acid Sequence↗
PubMed1994

Preliminary characterization of lymphoid hybridoma cell lines derived from the pregnant mouse uterus.

Seven independent cell lines were derived from the fusion of migratory cells recovered from explant cultures of metrial glands to SP 2/0, a non-Ig secreting B cell myeloma. The migrating cells came from a pool of metrial glands from day 6-8 pregnant random bred CD1 mice and were assumed to be cells early in the differentiation pathway to granulated metrial gland (GMG) cells. The fused cells were cloned twice at the limiting dilution. Hybridization was confirmed by quantitation of cellular DNA using propidium iodide staining and by karyotyping. Electron microscopy revealed that each of the hybrid cell lines was composed of cells which were lymphoid in appearance, but lacked the granules found in mature GMG cells. The surface phenotype of all lines is CD45+, LGL-1-, asialo GM-1-, IgG-, IgM-, CD3- and CD25- (p55 of IL-2 receptor). Although the hybridomas lack those phenotypic markers which were used to show that GMG cells are related to the natural killer (NK) cell lineage (ie LGL-1, asialo GM-1), they do express the pan-leukocyte marker CD45 as well as the lytic protein, perforin, at levels intermediate to those of SP 2/0 cells and GMG cells. In addition, the hybridomas were observed to preferentially bind the NK target cell YAC and to be capable of lytic activity at temperatures below 30 degrees C. Because these hybridomas may represent fusion to an early progenitor cell of the NK/GMG cell lineage, their continued characterization is of merit.

Animals↗
PubMed1994

In vivo phosphorylation of regulatory light chain of myosin II during mitosis of cultured cells.

Phosphorylation of the regulatory light chain of myosin II (MLC) controls the contractility of actomyosin in nonmuscle and muscle cells. It has been reported that cdc2 phosphorylates MLC in vitro at Ser-1 or Ser-2 and Thr-9 which protein kinase C phosphorylates (Satterwhite, L. L., M. J. Lohka, K. L. Wilson, T. Y. Scherson, L. K. Cisek, J. L. Corden, and T. D. Pollard. 1992 J. Cell Biol. 118:595-605). We have examined in vivo phosphorylation of MLC during mitosis and after the release of mitotic arrest. Phosphate incorporation of MLC in mitotic cells is found to be 6-12 times greater than that in nonmitotic cells. Phosphopeptide maps have revealed that the MLC from mitotic cells is phosphorylated at Ser-1 and/or Ser-2 (Ser-1/2), but not at Thr-9. MLC is also phosphorylated to a much lesser extent at Ser-19 which myosin light chain kinase phosphorylates. On the other hand, MLC of nonmitotic cells is phosphorylated at Ser-19 but not at Ser-1/2. The extent of phosphate incorporation is doubled at 30 min after the release of mitotic arrest when some cells start cytokinesis. Phosphopeptide analyses have revealed that the phosphorylation at Ser-19 is increased 20 times, while the phosphorylation at Ser-1/2 is decreased by half. This high extent of MLC phosphorylation at Ser-19 is maintained for another 30 min and gradually decreased to near the level of interphase cells as cells complete spreading at 180 min. On the other hand, phosphorylation at Ser-1/2 is decreased to 18% at 60 min, and is practically undetectable at 180 min after the release of mitotic arrest. The stoichiometry of MLC phosphorylation has been determined by quantitation of phosphorylated and unphosphorylated forms of MLC separated on 2D gels. The molar ratio of phosphorylated MLC to total MLC is found to be 0.16 +/- 0.06 and 0.31 +/- 0.05 in interphase and mitotic cells, respectively. The ratio is increased to 0.49 +/- 0.05 at 30 min after the release of mitotic arrest. These results suggest that the change in the phosphorylation site from Ser-1/2 to Ser-19 plays an important role in signaling cytokinesis.

Animals↗
PubMed1994

Mechanism of recovery in esophageal epithelia of rats with severe zinc deficiency.

Forty-six rats fed a Zn-deficient diet for 18 days, were divided into three groups and treated with Zn-deficient diet (GI), a normal (Zn-adequate) diet (GII) or a pharmacological Zn therapy diet (GIII) for 3 days. For light and electron microscopy, samples were taken at times 0, 8, 12, 24 and 72 h after treatment. In treatment GI, at all times, all rats had esophageal parakeratosis. With treatment GII, there was a variable progression toward normalization of the epithelium at 12 and 24 h. At 72 h there was almost complete recovery of normal epithelium. In treatment GIII at 8 h, large, light cells in the basal layer were shown to be present between dark cylindrical cells, a finding which was transitionary and disappeared at 12 h. Also, a thin keratinized layer was observed above the granular layer at 12 h. Recovery had progressed at 24 h and was complete after 72 h. The results are discussed in terms of a potential role of Zn in the sequence of cytochemical events in epithelial differentiation.

Animal Feed↗
PubMed1994

Epstein-Barr virus infection induces expression in B lymphocytes of a novel gene encoding an evolutionarily conserved 55-kilodalton actin-bundling protein.

A novel human mRNA whose expression is induced over 200-fold in B lymphocytes by latent Epstein-Barr virus (EBV) infection was reverse transcribed, cloned, and sequenced. The mRNA is predicted to encode a protein containing four peptides which precisely match amino acid sequences from a previously identified 55-kDa actin-bundling protein, p55. In vitro translation of the cDNA results in a 55-kDa protein which binds to actin filaments in the presence of purified p55 from HeLa cells. The p55 mRNA is undetectable in non-EBV-infected B- and T-cell lines or in a myelomonocytic cell line (U937). Newly infected primary human B lymphocytes, EBV-transformed B-cell lines, latently infected Burkitt tumor cells expressing EBNA2 and LMP1, a chronic myelogenous leukemia cell line (K562), and an osteosarcoma cell line (TK143) contain high levels of p55 mRNA or protein. In EBV-transformed B cells, p55 localizes to perinuclear cytoplasm and to cell surface processes that resemble filopodia. The p55 mRNA is detected at high levels in spleen and brain tissues, at moderate levels in lung and placenta tissues, and at low levels in skeletal muscle, liver, and tonsil tissues and is undetectable in heart, kidney, pancreas, and bone marrow tissues. Immunohistochemical staining of human brain tissue demonstrates p55 localization to the perinuclear cytoplasm and dendritic processes of many, but not all, types of cortical or cerebellar neurons, to glial cells, and to capillary endothelial cells. In cultured primary rat neurons, p55 is distributed throughout the perinuclear cytoplasm and in subcortical filamentous structures of dendrites and growth cones. p55 is highly evolutionarily conserved since it shows 40% amino acid sequence identity to the Drosophila singed gene product and 37% identity to fascin, an echinoderm actin-bundling protein. The evolutionary conservation of p55 and its lack of extensive homology to other actin-binding proteins suggest that p55 has specific microfilament-associated functions in cells in which it is differentially expressed, including neural cells and EBV-transformed B lymphocytes.

Amino Acid Sequence↗
PubMed1994

In vivo magnetic resonance imaging study of Kupffer cell involvement in CCl4-induced hepatotoxicity in rats.

When carbon tetrachloride (CCl4) was administered to rats, a localized region of hepatic edema could be detected within 1 h by in vivo proton magnetic resonance imaging. However, if rats were pretreated with gadolinium chloride (GdCl3), an inhibitor of Kupffer cell function, the CCl4-induced edema was greatly decreased. Methyl palmitate, another Kupffer cell inhibitor, also decreased the degree of edema caused by the administration of CCl4. Electron micrographs of samples that were taken from regions of the liver where the edema was localized indicated formation of vacuoles and lipid droplets in parenchymal cells and enlargement of Kupffer cells, which exhibited numerous phagosomes and extensive pseudopod formation. These electron micrograph changes were also attenuated by pretreatment of the rats with GdCl3 and methyl palmitate. In vivo spin trapping and electron paramagnetic resonance experiments indicated that GdCl3 did not affect the metabolism of CCl4 to the trichloromethyl radical. The data in this report suggest that localized hepatic edema which occurs soon after administration of CCl4 involves activation of Kupffer cells, and that trichloromethyl radical production may be a separate but related process occurring in parenchymal cells. These observations support reports from other laboratories that Kupffer cells may be involved in CCl4-induced hepatotoxicity.

Animals↗
PubMed1994

Malignant trigeminal schwannoma associated with xeroderma pigmentosum--case report.

A 46-year-old male with xeroderma pigmentosum developed an intracranial malignant schwannoma originating from the second branch of the left trigeminal nerve. The tumor was subtotally removed and postoperative radiation therapy given, but the tumor recurred twice over 3 years, and extended to the third branch of the left trigeminal nerve and the ipsilateral facial nerve. Radical surgery and radiation therapy finally achieved a cure. This is the first case of malignant trigeminal schwannoma with xeroderma pigmentosum, although various other internal neoplasms including central nervous system tumors have been reported in xeroderma pigmentosum patients. Radical surgery and radiation therapy are effective for treating intracranial malignant schwannoma. Radiation therapy is considered safe for xeroderma pigmentosum patients.

Cranial Nerve Neoplasms↗
PubMed1994

Informative usefulness of age, sex and vital signs in the differential diagnosis of disturbed consciousness among 175 emergency outpatients.

Final diagnoses were determined among 175 emergency patients with disturbed consciousness with a Glasgow Coma Scale (GCS) of less than 15 and diagnostic usefulness of basic information was assessed using clinico-epidemiological indices. Subject patients included 98 males and 77 females with average age 53.4 years. Final diagnoses were as follows: intracranial lesions in 69 patients (39.4%), metabolic and systemic diseases in 97 (55.4%), mental diseases in 4 (2.3%), and diseases of unknown origin in 5 (2.9%). Cerebrovascular disorders and epilepsy were most frequent among the intracranial lesions, and poisoning, hypoglycemia, acute alcoholism and hypoxic encephalopathy among the metabolic and systemic diseases. Informative usefulness of age, sex and vital sings in diagnosing cerebrovascular disorders was analyzed with the use of ROC curves, showing that cut-off points of age over 60 years and of systolic blood pressure greater than 160 mmHg were most useful.

Age Factors↗
PubMed1994

Tumor-derived monocyte chemoattractant protein-1 induces intratumoral infiltration of monocyte-derived macrophage subpopulation in transplanted rat tumors.

By immunohistochemistry using anti-rat macrophage monoclonal antibodies RM-1, ED1, ED2, ED3, TRPM-3, and Ki-M2R, we studied transplanted rat tumors of 9L (rat gliosarcoma), Ad-2 (rat mammary carcinoma), and MT-P (rat malignant fibrous histiocytoma) cell lines to examine the distribution pattern of macrophages within and around the tumors. Most tumor-associated macrophages expressed RM-1, ED1, and Ia antigens, indicating activated macrophages. Based on differences in their immunophenotypical expression, these macrophages were distinguished into two major subpopulations. One expressed TRPM-3 and/or ED3, and the other was positive for ED2 and Ki-M2R. The former was considered to be monocyte-derived macrophages, whereas the latter showed the immunophenotype of tissue-fixed, resident macrophages. Infiltration and distribution patterns in the two macrophage subpopulations differed in the three different tumors. Monocyte-derived, activated macrophages infiltrated into 9L- and Ad-2-transplanted tumors, which markedly produced monocyte chemoattractant protein-1 (MCP-1). Additionally, numerous ED2- and Ki-M2R-positive macrophages were observed within the Ad-2-transplanted tumors, and some of them expressed TRPM-3. However, there were few macrophages in the MT-P-transplanted tumors that showed no MCP-1 production. In transplanted tumors of four MT-P/MCP-1 cell lines established by transfecting a rat MCP-1 gene expression vector (pCEP4/MCP-1) into the MT-P cell line, different levels of MCP-1 production were detected, which correlated well with the numbers of intratumorally infiltrated TRPM-3-positive macrophages. In contrast, ED2- and Ki-M2R-positive macrophages were not detected in any MT-P/MCP-1-transplanted tumors. MT-P/MCP-1-transplanted tumors exhibited lower growth rate than parental MT-P-transplanted tumors. These results indicate that tumor-derived MCP-1 induces intratumoral infiltration of monocyte-derived macrophages, but not macrophages with the immunophenotype of tissue-fixed, resident type. The former population of macrophages seems to have a suppressive effect on the growth of tumors.

Animals↗