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S Natori

Publications and source records attributed to S Natori.

At least 19 recordsLinked to original sources
PubMed2001

Adenosine deaminase activity of insect-derived growth factor is essential for its growth factor activity.

Insect-derived growth factor (IDGF) was originally isolated from conditioned medium of NIH-Sape-4 cells derived from flesh fly embryos. Here we demonstrated that IDGF has adenosine deaminase activity. The substrate specificity of IDGF was similar to that of the mammalian cytoplasmic adenosine deaminase. The adenosine deaminase activity of IDGF was shown to be indispensable for its growth factor activity toward NIH-Sape-4 cells. We found that there are specific binding sites for IDGF on the surface of NIH-Sape-4 cells and that it binds to these sites with a K(d) value of 2.4 x 10(-10) m. We propose that the cell surface binding sites for IDGF are specific receptors modified with an adenosine moiety. When IDGF binds to these receptors, it may deaminate the adenosine moiety, and this process may be prerequisite for the signal transduction via this receptor.

Adenosine Deaminase↗
PubMed2001

Interaction between ATBP and DmUbc9 in the expression of the Sarcophaga lectin gene.

We previously demonstrated that (A+T)-stretch binding protein (ATBP) and Dorsal-related immunity factor (Dif) are required for the expression of the Sarcophaga lectin gene in SL-2 cells (Aozasa et al., Eur. J. Biochem. 268, 2506-2511, 2001). The present study demonstrates that DmUbc9 interacts with ATBP, and cotransfection of the DmUbc9 vector with ATBP and Dif vectors greatly enhances the expression of the luciferase reporter of the Sarcophaga lectin gene in SL-2 cells. These results suggest that sumoylation of ATBP is involved in the expression of the Sarcophaga lectin gene in this system.

Animals↗
PubMed2001

Hepatocyte apoptosis is a pathologic feature of human alcoholic hepatitis.

BACKGROUND/AIMS: The pathogenesis of alcoholic hepatitis (AH) remains poorly understood. Although apoptosis is now recognized as a mechanism of liver injury, the extent and mechanisms of apoptosis in human AH remain unknown. Thus, our aims were to quantify hepatocyte apoptosis in patients with AH, correlate it with disease severity, and identify the mechanisms of apoptosis induction. METHODS: Hepatocyte apoptosis was assessed in 26 patients with AH and 27 controls without liver disease using the TUNEL assay and immunohistochemistry for activated caspase 3. Liver specimens were also graded for disease severity. The expression of the death receptors, Fas and tumor necrosis factor-alpha receptor 1 (TNF-R1), was assessed by immunohistochemistry. RESULTS: In contrast to normal livers, TUNEL- and caspase 3-positive hepatocytes were readily observed in the livers of patients with AH. In the AH group, hepatocyte apoptosis was significantly higher in patients with a serum bilirubin of > 3 mg/dl. Apoptosis was also greater in grade 4 steatohepatitis. The Fas receptor was strongly expressed in hepatocytes in AH, but not in normal livers; the TNF-R1 expression was comparable in both groups. CONCLUSIONS: The present results demonstrate that hepatocyte apoptosis is significantly increased in human AH and justify therapeutic strategies aimed at inhibiting apoptosis in this disease.

Antigens, CD↗
PubMed2001

Targeted disruption of a pupal hemocyte protein of Sarcophaga by RNA interference.

Previously, we purified a transmembrane protein with a molecular mass of 120 kDa (p120) that is exclusively expressed in pupal hemocytes of Sarcophaga. In this study, we demonstrated that double-stranded RNA (dsRNA) injected into the larval body cavity effectively inhibited the expression of p120 in pupal hemocytes. Thus, RNA interference (RNAi) was found to be a useful technique for creating pupal hemocytes with a loss-of-function of a specific protein. The p120-less pupal hemocytes generated by RNAi were found to have lost the ability to take up acetylated low density lipoprotein, indicating that p120 is a scavenger receptor specifically expressed on the surface of pupal hemocytes.

Animals↗
PubMed2001

Identification of a novel gene, Mblk-1, that encodes a putative transcription factor expressed preferentially in the large-type Kenyon cells of the honeybee brain.

Mushroom bodies (MBs) are considered to be involved in higher-order sensory processing in the insect brain. To identify the genes involved in the intrinsic function of the honeybee MBs, we searched for genes preferentially expressed therein, using the differential display method. Here we report a novel gene encoding a putative transcription factor (Mblk-1) expressed preferentially in one of two types of intrinsic MB neurones, the large-type Kenyon cells, which makes Mblk-1 a candidate gene involved in the advanced behaviours of honeybees. A putative DNA binding motif of Mblk-1 had significant sequence homology with those encoded by genes from various animal species, suggesting that the functions of these proteins in neural cells are conserved among the animal kingdom.

Amino Acid Sequence↗
PubMed2001

Activation of the Sarcophaga lectin gene promoter by (A + T)-stretch binding protein.

Previously, we purified and isolated a cDNA for (A + T)-stretch binding protein (ATBP) that binds to (A + T)-stretches in the 5' upstream region of the Sarcophaga lectin gene [Nakanishi-Matsui, M., Kubo, T. & Natori, S. (1995) Eur. J. Biochem. 230, 396-400]. Here, we used a luciferase reporter to examine the effect of ATBP on transcription of the Sarcophaga lectin gene. Deletion experiments revealed that ATBP activates the Sarcophaga lectin gene in a 5' upstream sequence-dependent manner, and that at least the N-terminal 25 residues, the three Zn-finger domains, an acidic domain and the third hydrophobic domain of ATBP are indispensable for its function. Furthermore, a synergistic effect was detected between ATBP and Dif, suggesting that ATBP is involved in the activation of insect immunity genes.

Animals↗
PubMed2001

Cloning of cDNA for cathepsin B mRNA 3'-untranslated-region-binding protein (CBBP), and characterization of recombinant CBBP.

Previously, we purified the cathepsin B mRNA 3'-untranslated-region-binding protein (CBBP) from Sarcophaga and suggested its participation in the translational regulation of cathepsin B mRNA in this insect. In this study, we isolated a full length cDNA for CBBP. CBBP was an RNA-binding protein that contained four RGG boxes and four zinc finger motifs required for RNA binding. CBBP was shown to be localized in both the nuclei and cytoplasm of Sarcophaga hemocytes. Recombinant CBBP bound to the entire region of cathepsin B mRNA and repressed its translation in vitro.

3' Untranslated Regions↗
PubMed2001

Identification and characterization of an antibacterial peptide of the 26-kDa protease of Sarcophaga peregrina with antibacterial activity.

Previously, we purified a serine protease with a molecular mass of 26 kDa that exhibits potent antibacterial activity from a pupal extract of Sarcophaga peregrina (flesh fly). We divided this protease into 12 peptides and examined their antibacterial activity. A peptide corresponding to residues 155 to 174 (peptide 9) was found to exhibit antibacterial activity comparable to that of the 26-kDa protease. When Escherichia coli was treated with peptide 9, the permeability of both the outer and inner membranes increased, and substrates for beta-lactamase and beta-galactosidase entered the cells, but beta-galactosidase did not leak out of the cells under these conditions. It was suggested that residues 6 to 18 of peptide 9 form an amphiphilic alpha-helix under hydrophobic conditions with an N-terminal basic loop and then interact with acidic phospholipids in the bacterial membranes.

Amino Acid Sequence↗
PubMed2001

Effects of angiotensin converting enzyme inhibitor and angiotensin II type 1 receptor blocker on cardiac dysfunction induced by isoproterenol in dogs.

We examined whether angiotensin converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor blockers (ARB) prevent isoproterenol (ISO)-induced left ventricular (LV) dysfunction in dogs. The effects of a large dose of ISO, 1 microg/kg/min, 3 h infusion, were investigated in three groups with simultaneous infusion of an ACE inhibitor (quinaprilat), ARB (candesartan) or saline. ISO infusion significantly decreased LV dP/dt, LV ejection fraction and LV fractional shortening, and significantly increased tau, the time constant of isovolume relaxation of LV, and LV end diastolic pressure. All of these changes were significantly attenuated in both the ACE inhibitor and ARB groups, especially in the ARB group. Serum levels of creatinin kinase isoform MB, lactate dehydrogenase and lipid peroxide were significantly increased by ISO. However, the increases in these markers of myocardial damage were significantly diminished by simultaneous infusion of an ACE inhibitor or ARB, especially by ARB. In conclusion, an ACE inhibitor and ARB prevent LV systolic and diastolic dysfunction as well as myocardial damage induced by excess beta-adrenergic stimulation.

Adrenergic beta-Agonists↗
PubMed2001

Activation of human monocyte cell line U937 via cell surface calreticulin.

U937 cells were found to be activated by an antibacterial peptide, KLKLLLLLKLK-NH2 (L5), to generate superoxide anion (O2-)-like peripheral neutrophils. However, the state of cell surface calreticulin, a possible receptor for L5, was suggested to differ between neutrophils and U937 cells. Unlike the former, the latter ones were activated by anti-C-domain peptide antibody of calreticulin even in the absence of L5 and generated O2- in a GTP-binding protein (G-protein)-dependent manner.

Animals↗
PubMed2001

[A case of breast cancer with bone marrow and liver metastases responding completely to low-dose weekly paclitaxel combined with toremifene].

A 36-year-old woman was admitted to our hospital because of general malaise in October 1999. She was diagnosed with bilateral breast cancer with bone marrow and liver metastases. Low-dose weekly paclitaxel (60 mg/body/week) combined with toremifene (120 mg/day) was started in December 1999. Myelofunction was recovered after 2 weeks of chemotherapy (CT), and the primary tumors and cervical/axillary lymphadenopathy disappeared after 4 weeks of CT. Bone marrow and liver metastases was no longer detected after 16 weeks of CT, and the case was evaluated as a complete response (CR). The same therapy has been performed for eight months and no evidence of recurrence has been observed.

Adult↗
PubMed2000

Male-specific IDGF, a novel gene encoding a membrane-bound extracellular signaling molecule expressed exclusively in testis of Drosophila melanogaster.

We identified a novel gene of Drosophila melanogaster, Male-specific IDGF (MSI), encoding a transmembrane signaling molecule with exclusive expression in the testis. This molecule (MSI) contains a single transmembrane domain and has 35% amino acid identity with insect-derived growth factor (IDGF), a soluble growth factor for embryonic cells of the flesh fly, Sarcophaga peregrina. When MSI was exogenously expressed in Schneiders's line 2 cells, it was shown to be localized on the cell surface and exhibits growth factor activity, suggesting that MSI is a membrane-bound extracellular signaling molecule. Gene expression studies revealed that MSI mRNA was restricted to mature primary spermatocytes, whereas MSI was detected in the cells at the later developmental stages. Analysis using four meiotic arrest mutants, aly, can, mia, and sa suggested that MSI is involved in spermiogenesis, the final differentiation step of spermatogenesis. These results suggest that MSI is an extracellular signaling molecule participating in spermatogenesis and is a new member of the IDGF family.

Amino Acid Sequence↗
PubMed2000

Participation of transcription elongation factor XSII-K1 in mesoderm-derived tissue development in Xenopus laevis.

We isolated a cDNA clone for a novel member of the S-II family of transcription elongation factors from Xenopus laevis. This S-II, named XSII-K1, is assumed to be the Xenopus homologue of mouse SII-K1 that we reported previously (Taira, Y., Kubo, T., and Natori, S. (1998) Genes Cells 3, 289-296). Expression of the XSII-K1 gene was found to be restricted to mesoderm-derived tissues such as liver, kidney, and skeletal muscle. Contrary to the general S-II gene, expression of the XSII-K1 gene was not detected in embryos at stages earlier than 11. The animal cap assay revealed that activin A, but not basic fibroblast growth factor, induced expression of the XSII-K1 gene and that it participated in the expression of mesoderm-specific genes such as Xbra and Xalpha-actin. This is the first demonstration that the regulation at the level of transcription elongation is included in the development of mesoderm-derived tissues.

Actins↗
PubMed2000

Transcription elongation factor S-II confers yeast resistance to 6-azauracil by enhancing expression of the SSM1 gene.

Loss of function of S-II makes yeast sensitive to 6-azauracil. Here, we identified a multi-copy suppressor gene of this phenotype, termed SSM1 (suppressor of 6-azauracil sensitivity of the S-II null mutant 1), that encodes a novel protein consisting of 280 amino acid residues. Although both the SSM1 null mutant and the S-II/SSM1 double null mutant were viable under normal growth conditions, they resembled the S-II null mutant in being sensitive to 6-azauracil. Expression of the SSM1 gene was found to be repressed in the S-II null mutant but was restored by overexpression of chimeric S-II molecules that were able to stimulate transcription elongation by RNA polymerase II in vitro. Furthermore, we identified two transcription arrest sites within the transcription unit of the SSM1 gene in vitro that could be relieved by S-II. These results indicate that S-II confers yeast resistance to 6-azauracil by stimulating transcription elongation of the SSM1 gene.

5'-Nucleotidase↗
PubMed2000

Activation of murine macrophage-like cells by granulocytin.

Granulocytin, a C-type lectin from Sarcophaga peregrina (flesh fly), stimulated glucose consumption and cytokine production by the mouse macrophage-like cell line J774.1. When J774.1 cells were pretreated with tunicamycin, their granulocytin-dependent TNF-alpha production was greatly reduced. These results suggest that the stimulus of granulocytin is transmitted to J774.1 cells via the carbohydrate chain of granulocytin receptors located on their surface.

Animals↗
PubMed2000

Gene structure and chromosome mapping of mouse transcription elongation factor S-II (Tcea1).

We report the organization and chromosome localization of the mouse transcription elongation factor S-II gene (Tcea1). This gene was found to be a single copy gene consisting of 10 exons spanning approximately 30kb. Its organization was the same as those of the mouse testis-specific S-II gene (Tcea2) and Xenopus general S-II gene (xTFIIS.oA), but different from that of the human S-II gene family. We also identified a processed pseudogene (Tcea1-ps1) with a sequence highly homologous to those of S-II cDNAs but containing a translation termination codon within its open reading frame. Linkage analysis showed that Tcea1 and Tcea1-ps1 are mapped on mouse chromosomes 1 and 15, respectively. Relationships between Tcea1 and S-II cDNAs isolated so far are discussed.

Animals↗