Search PubMed⌕ Search

Biomedical subjects

M Hatanaka

Publications and source records attributed to M Hatanaka.

At least 199 records · Page 11Linked to original sources
PubMed1990

Protein kinase inhibitor H-7 blocks accumulation of unspliced mRNA of human T-cell leukemia virus type I (HTLV-I).

Rex, the post-transcriptional regulator of human T-cell leukemia virus type I (HTLV-I), is known to induce accumulation of the unspliced viral gag-pol mRNA. Rex is a phosphoprotein found in the cell nucleolus, whose function may be regulated by its localization and phosphorylation. We have examined the role of phosphorylation on Rex function by using a protein kinase inhibitor, H-7 [1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine]. Treatment of an HTLV-I infected human T-cell line with H-7 blocked specifically accumulation of the unspliced gag-pol mRNA, resulting in the decreased Gag protein synthesis that corresponds with the decreased in vivo phosphorylation of Rex. In contrast, other viral and cellular products have not been influenced by the level of H-7 used. Therefore, the phosphorylation of Rex is required for the viral RNA partition of HTLV-I.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Epidermal growth factor stimulates the anchorage-independent growth of human squamous cell carcinomas overexpressing its receptors.

We examined the effects of epidermal growth factor (EGF) on the anchorage-dependent and -independent growth of four human squamous carcinoma cell lines that overexpress EGF receptors. While EGF inhibited anchorage-dependent growth, it stimulated anchorage-independent growth of all four cell lines tested. The results suggest that the proliferative responses to EGF are characterized by a preference for anchorage-independent, rather than -dependent growth, in cells overexpressing EGF receptors. Moreover, as EGF has been shown to stimulate the in vivo growth of squamous carcinoma cells overexpressing EGF receptors, it is also suggested that the in vitro EGF responsiveness of these cells in soft agar, but not in monolayer, better correlates with the in vivo EGF responsiveness.

Carcinoma, Squamous Cell↗
PubMed1990

Soluble factors including proteinases released from damaged cells may trigger the wound healing process.

The wound healing process is initiated as soon as tissue is injured. Herein, we demonstrate that c-fos and c-myc mRNA transcripts are promptly increased in the wounded tissue in vivo and in vitro. A buffer solution from scraped serum-starved quiescent fibroblasts, when added to resting fibroblasts, caused the increase of c-fos and c-myc mRNA among the indicator cells. Soluble factors contained in the wounding supernatant are responsible for these phenomena and we call them wounding factors. Addition of proteinase inhibitors to the culture medium drastically reduced the c-fos mRNA induction by the wounding factors. Exogenously added trypsin or thrombin mimicked the activity of wounding factors. These results suggest that wounding causes soluble factors including various proteinases to be released from the damaged cells, which trigger the adjacent cells to respond to the injury.

Animals↗
PubMed1990

[Simplified intraarterial infusion and angiographic method for rabbit VX-2 hind limb tumor via the saphenous artery].

We developed a new simplified intraarterial infusion and angiographic method for rabbit VX-2 hind limb tumors. A 24 gauge cannula was placed in the saphenous artery of the tumor-bearing leg (not supplying the tumor) and used for intraarterial drug infusion or angiography. This method has several advantages as follows: 1) easy and time-saving in manipulation (about 15 minutes per a rabbit); 2) selective drug infusion into the tumor-supplying artery without fluoroscopy; 3) sequential follow-up angiographies available for weeks.

Animals↗
PubMed1990

Characterization of a functional domain of human calpastatin.

Expression plasmids were constructed from the cDNA of human calpastatin to examine the contribution to the inhibition of calpain of highly conserved sequences in each of four repetitive domains. A series of deletion derivatives of domain 1 proteins, truncated at either the amino or carboxy terminus, were produced in E. coli. Deletion from the amino terminus past the amino terminal conserved sequence decreased the inhibition. When the middle conserved sequence, the M-sequence, was further deleted, no inhibition was detected, but deletion from the carboxy terminus past the carboxy terminal conserved sequence did not decrease the inhibition until the M-sequence was reached. Nuclear magnetic resonance and circular dichroism spectra showed that domain 1 has an unfolded structure. Peptides that contained the M-sequence and some neighboring sequences were synthesized to measure the minimum size of the inhibitory peptide, which was the M-sequence with the next six residues on the amino terminal side.

Amino Acid Sequence↗
PubMed1990

Discovery of the nucleolar targeting signal.

The discovery of the signal peptides that direct proteins to localize at the nucleolus is described here. The nucleolar targeting signal termed the NOS consists of clustered basic amino acids organized such that a portion also functions as the nuclear transporting signal. Although a NOS has been identified within the regulatory genes of human retroviruses, HTLV-I and HIV-I, signals of similar function in cellular proteins--such as heat shock proteins--may be induced through the configurational change of protein structure by heat or stress.

Amino Acid Sequence↗
PubMed1990

HTLV-1 p27rex stabilizes human interleukin-2 receptor alpha chain mRNA.

Expression of the pX gene products (p40tax, p27rex and p21X-III) of human T cell leukemia virus type 1 (HTLV-1), which is known to be a causative agent of adult T cell lymphoma/leukemia, induces expression of the interleukin-2 receptor alpha chain (IL-2R alpha) on infected T cells. Comparison of IL-2R alpha promoter activities has revealed that the transcriptional activation of the promoter alone cannot explain the large numbers of IL-2R alpha expressed on HTLV-1 infected cells. We found that the rates of the IL-2R alpha mRNA degradation were greatly reduced in pX-positive cells as compared with pX-negative cells. Simultaneous transfection of the expression vector plasmid containing IL-2R alpha cDNA and similar plasmids containing various pX sequences showed that p27rex elongated the half life of IL-2R alpha mRNA. As p27rex did not affect the transport of the IL-2R alpha mRNA from nucleus to cytoplasm, prolongation of the IL-2R alpha mRNA half life by p27rex is ascribed to stabilization of the mRNA. Experiments using deletion mutants and chimeric constructs of the IL-2R alpha cDNA demonstrated that the coding sequence but not the 5' or 3' untranslated region of the IL-2R alpha mRNA sequence is responsible for its protection by p27rex.

Cell Line↗
PubMed1990

Spontaneous and cAMP-dependent induction of a resting phase and neurite formation in cell hybrids between human neuroblastoma cells and thymidine auxotrophs of rat nerve-like cells.

Cell hybrids (BIM) were produced between human neuroblastoma cells (IMR-32) and thymidine auxotrophs (B3T) of rat nerve-like cells (B103) in order to obtain cell lines undergoing stable neuronal differentiation. BIM cells exhibited the growth properties of partial transformation: 1) When the cell growth reached a plateau, BIM cells ceased to proliferate and expressed a differentiated phenotype. The shape of the cells changed from flat to round and they extended neurites. 2) When cultured in methylcellulose, BIM cells formed colonies, indicating that BIM cells have the ability of anchorage-independent growth. By Southern blot analysis, BIM cells had both human and rat types of N-myc genes. The human N-myc genes were amplified, but the extent of the amplification was lower in BIM cells than that in the parental cell line IMR-32. The rat N-myc gene was detected at a similar level in BIM, B3T, B103, and rat fibroblastic cells 3Y1. Therefore, the decrease in amplification of human N-myc genes may be involved in the properties of partial reverse-transformation in BIM cells. When treated with various drugs such as db-cAMP, forskolin, and cAMP with isobutyl-methylxanthine, BIM cells expressed a nerve-like phenotype. These findings indicate that cell hybridization yielded partial normalization of transformed nerve-like cells.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Increased expression of genes for basic fibroblast growth factor and transforming growth factor type beta 2 in human benign prostatic hyperplasia.

It is now widely accepted that factors other than androgen are crucial in the normal and abnormal growth of the prostate, including human benign prostatic hyperplasia (BPH). Using a Northern blot analysis, we examined human normal and benign hyperplastic prostates for expressions of basic fibroblast growth factor (FGF), acidic FGF, transforming growth factor type beta 2 (TGF-beta 2), TGF-beta 1, and epidermal growth factor (EGF). Basic FGF mRNAs were detectable in all the prostates examined. In addition, levels of basic FGF expression were significantly higher in BPH than in normal prostate. Acidic FGF transcripts were undetectable except in one case of BPH. Although both TGFs were expressed in all the samples, TGF-beta 2 showed significantly increased levels of expression in BPH as compared to those in normal prostate, while TGF-beta 1 did not. No EGF was expressed in any of the prostates examined. These findings suggest that specific growth factors (basic FGF and TGF-beta 2) produced locally in the prostate may be involved in BPH development.

Aged↗
PubMed1990

Genetic heterogeneity in blast crisis of chronic myelocytic leukemia.

Fourteen patients with lymphoid and mixed blast crisis (BC) of chronic myelocytic leukemia were studied by immunophenotyping and genotyping. Rearrangements of immunoglobulin heavy chain (IgH), T-cell receptor (TcR) gamma and TcR beta genes were detected in all 14, in nine and in four patients, respectively. Interestingly, more than two rearranged bands of IgH gene in three lymphoid BC and two rearranged bands with germ line band in 1 biphenotypic BC indicated the genetic heterogeneity of the blasts. Some blastic transformations are thought to occur at a more immature stage of hematopoietic differentiation than that indicated by the phenotype and genotype of BC cells.

Antigens, Differentiation↗
PubMed1990

Gene expression of fibroblast growth factors in human gliomas and meningiomas: demonstration of cellular source of basic fibroblast growth factor mRNA and peptide in tumor tissues.

The growth autonomy of human tumor cells is considered due to the endogenous production of growth factors. Transcriptional expression of candidates for autocrine stimulatory factors such as basic fibroblast growth factor (FGF), acidic FGF, and transforming growth factor type beta were determined in human brain tumors. Basic FGF was expressed abundantly in 17 of 18 gliomas, 20 of 22 meninglomas, and 0 of 5 metastatic brain tumors. The level of mRNA expression of acidic FGF in gliomas was significant. In contrast, transforming growth factor type beta 1 was expressed in all the samples investigated. The mRNA for basic FGF and its peptide were localized in tumor cells in vivo by in situ hybridization and immunohistochemistry, showing that basic FGF is actually produced in tumor cells. Our results suggest that tumor-derived basic FGF is involved in the progression of gliomas and meningiomas in vivo, whereas acidic FGF is expressed in a tumor origin-specific manner, suggesting that acidic FGF works in tandem with basic FGF in glioma tumorigenesis.

Blotting, Northern↗
PubMed1990

Oncogenic transformation by the tax gene of human T-cell leukemia virus type I in vitro.

Human T-cell leukemia virus type I (HTLV-I) is a causative agent of adult T-cell leukemia (ATL). To elucidate the role of HTLV-I in leukemogenesis, we examined the biological activity of a defective HTLV-I provirus with the env-pX 3' long terminal repeat region cloned from leukemic cells of an ATL patient. Transfection experiments showed growth stimulation of NIH 3T3 cells--growing beyond the saturation density and growing in soft agar. Since the pX sequence is known to encode three proteins, Tax, Rex, and p21x, the biological activity of each pX gene was examined separately. The growth-stimulating activity was induced only by the tax gene in NIH 3T3 cells and Rat-1 cells. Furthermore, the tax gene induced tumorigenicity in nude mice when introduced into Rat-1 cells. Thus, a transcriptional transactivator gene of HTLV-I, tax, is clearly identified as a viral oncogene without a cellular homolog. The transforming activity of tax, possibly via a transcriptional deregulation of cell growth control, may play an important role in leukemogenesis of ATL in addition to its aberrant stimulation of the interleukin 2 system.

Animals↗
PubMed1990

2,3 Dimercapto-1-propanol inhibits HIV-1 tat activity, viral production, and infectivity in vitro.

We have examined the effect of 2,3 dimercapto-1-propanol (DMP), which is known as an anti-heavy metal-poisoning drug, against human immunodeficiency virus type 1 (HIV-1). We demonstrate that DMP inhibited transactivation directed by tat protein, which is a metal containing transcriptional transactivating factor and also interfered with viral production. Furthermore, treatment and pretreatment of cells with DMP strongly reduced their sensitivity for HIV-1 infection through unknown mechanisms. These results indicate that DMP reveals pleuripotent effects on HIV-1 infection and production in vitro and thus may provide an exploitable hypothesis for designing new drugs against AIDS.

Amino Acid Sequence↗
PubMed1990

Analysis of influenza A virus temperature-sensitive mutants with mutations in RNA segment 8.

Temperature-sensitive (ts) mutants of influenza virus strain A/Udorn/72 (H3N2 subtype) with lesions in RNA segment 8 exhibited intrasegmental complementation, and were divided in two complementation groups (H1 and H2) on MDCK cells. The nucleotide sequence of segment 8 was determined for three of these mutants. The H1 strains, ICR1629 and SPC45, have a single amino acid substitution in the coding region of the non-structural protein NS1, whereas the H2 strain, ICR516, has a substitution in the NS2-coding region. With both NS1 ts mutants, the synthesis of two late proteins, the matrix protein (M1) and haemagglutinin (HA), was greatly reduced and NS1 synthesis also decreased at 40 degrees C (non-permissive temperature) compared to that at 34 degrees C (permissive temperature). The synthesis of each virus-specific RNA was analysed using a quantitative hybridization method. However, at 40 degrees C, the levels of individual mRNAs including those for the late proteins, were almost the same as those at 34 degrees C, and attained the wild-type levels later in the infection (5 h post-infection) when the synthesis of the late proteins and the NS1 protein was severely reduced. The observations suggest that the NS1 protein, which is a nuclear protein, is involved in some post-transcriptional processes in the synthesis of the late proteins and the NS1 protein.

Animals↗
PubMed1990

Effects of a highly basic region of human immunodeficiency virus Tat protein on nucleolar localization.

Human immunodeficiency virus type 1 encodes a positive trans-activator protein, Tat, which is located predominantly in the cell nucleolus. To study the role of the basic region of Tat in nucleolar localization, we constructed fusion genes encoding serially deleted segments of Tat joined to the amino-terminal end of the Escherichia coli beta-galactosidase molecule. We show that the basic region of Tat was sufficient for nuclear localization but not for nucleolar localization. Addition of three amino acids (59, 60, and 61) of the Tat sequence at the C-terminal end of the basic region was necessary for the chimeric beta-galactosidase to localize in the nucleus as well as in the nucleolus. We demonstrate that a short amino acid sequence (G-48 RKKRRQRRRA HQ N-61), when fused to the amino terminus of beta-galactosidase, can act as a nucleolar localization signal.

Amino Acid Sequence↗
PubMed1990

Synthetic cephalosporins. VI. Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxy-1-methyl) ethoxyiminoacetamido]- 3-(3-hydroxy-4-pyridon-1-yl)methyl-3-cephem-4-carboxylic acid and related compounds.

Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxy-1-methyl)ethoxyimin oacetamido]- 3-(3-hydroxy-4-pyridon-1-yl)-3-cephem-4-carboxylic acid (12) and its related compounds are described. Compound 12 exhibited excellent antibacterial activity against gram-negative bacteria, and its anti-pseudomonal activity was ten to fifteen times greater than that of ceftazidime.

Cephalosporins↗
PubMed1990

Synthesis and pharmacological properties of N-[3-(3-(1-Piperidinylmethyl)phenoxy)propyl]-2-(2-hydroxyethylthio)- acetamide and related compounds as antiulcer agents. I.

N-Phenoxypropylacetamide derivatives were prepared and tested for antiulcer activity. These compounds exhibited both gastric acid antisecretory and cytoprotective properties. Structure-activity studies led to the identification of N-[3-(3-(1-piperidinylmethyl)phenoxy)propyl]-2-(2-hydroxyethylt hio)acetamide (8), which was selected for further development and clinical evaluation.

Animals↗