Biomedical subjects

H Ariga

Publications and source records attributed to H Ariga.

At least 37 records · Page 2Linked to original sources

PubMed2000

CDC6 interacts with c-Myc to inhibit E-box-dependent transcription by abrogating c-Myc/Max complex.

The c-myc oncogene product (c-Myc) is a transcription factor that dimerizes with Max and recognizes the E-box sequence. It plays key functions in cell proliferation, differentiation and apoptosis. It is generally thought that c-Myc transactivates genes encoding proteins essential to cell-cycle progression by binding to the E-boxes that control them. The functions of c-Myc are also thought to be modulated by its associated proteins, several of which have recently been identified. In this study, we found that c-Myc directly bound in vivo and in vitro to the N-terminal region of human CDC6, a component of the pre-replication complex, and that both co-localized in cell nuclei. CDC6 bound to the C-proximal region of c-Myc, thereby competing with Max on the E-box sequence and changing c-Myc/Max heterodimer to a Max/Max homodimer. In consequence, the E-box-dependent transcription activity of c-Myc was abrogated. These results suggest that, in addition to its DNA replication activity, CDC6 also has a role as a transcriptional suppressor of c-Myc.

Basic Helix-Loop-Helix Leucine Zipper Transcriptio↗

PubMed2000

MSSP, a protein binding to an origin of replication in the c-myc gene, interacts with a catalytic subunit of DNA polymerase alpha and stimulates its polymerase activity.

MSSP has been identified as a protein that binds to both single- and double-stranded sequences of a putative DNA replication origin sequence in the human c-myc gene. MSSP possesses versatile functions, including stimulation of DNA replication, transcriptional regulation, apoptosis induction, and cell transformation coordinated by c-Myc. MSSP contains two RNP domains, RNP1-A and RNP1-B, both of which are necessary for all of the functions of MSSP. In this study, we found that MSSP binds to the N-terminal region of a catalytic subunit of a human DNA polymerase alpha via its RNP domains both in vitro and in human cells. Furthermore, MSSP was released from the putative DNA replication origin of the c-myc gene after it complexed with DNA polymerase alpha, and MSSP stimulated DNA polymerase activity in vitro.

Cell Line↗

PubMed2000

Primary structure, genomic organization and expression of the major secretory protein of murine epididymis, ME1.

The mouse cDNA and its genomic clones encoding the epididymal secretory glycoprotein ME1 were identified. The Me1 gene spans 15kb with four exons and three introns. The deduced amino-acid sequence of the ME1 cDNA revealed that it consists of 149 amino acid residues, which contain a signal peptide characteristic of secretory proteins, six cysteine residues and a proline-rich region conserved in the orthologous proteins. Northern blot analysis revealed that 1.3kb ME1 mRNA is highly expressed in the mouse epididymis. The polyclonal antibodies generated against human HE1 (ME1 orthologous protein) expressed in bacteria reacted with approximately 17 to 25kDa components in mouse epididymis crude extract. The reduction of the molecular mass of the recombinant ME1 protein with the digestion of glycopeptidase A indicated that it is modified by Asn-linked glycosylation.

Amino Acid Sequence↗

PubMed2000

Reciprocal regulation via protein-protein interaction between c-Myc and p21(cip1/waf1/sdi1) in DNA replication and transcription.

The c-myc protooncogene product (c-Myc) is a transcription factor and is rapidly induced in resting cells following various mitogenic stimuli. c-Myc is thus suggested to play an important role in the transition from quiescence to proliferation. Despite numerous studies, including those on the connection between cyclin E/cyclin-dependent kinase 2 and c-Myc, little has been clarified about c-Myc in terms of the cell cycle regulation. Here we show that c-Myc can directly bind to the carboxyl-terminal region of the cyclin-dependent kinase inhibitor p21(cip1/waf1/sdi1) and thus partially relieves the p21 of the inhibitory effect on DNA synthesis directed by the proliferating cell nuclear antigen-dependent DNA polymerase delta. As for transcription, on the other hand, the p21 binding to the Myc box II region of c-Myc blocks c-Myc-Max complex formation on the E-box and thereby suppresses the transcriptional activation from the E-box by c-Myc. These results suggest that c-Myc activates DNA replication via inactivation of p21 and that p21, vice versa, represses the transcriptional activity of c-Myc. The balance of the reciprocal inactivation between c-Myc and p21 may determine the course of cellular processes such as cell proliferation, differentiation, and apoptosis.

Binding Sites↗

PubMed2000

Identification of heterochromatin protein 1 (HP1) as a phosphorylation target by Pim-1 kinase and the effect of phosphorylation on the transcriptional repression function of HP1(1).

Pim-1, a protooncogene product, is a serine/threonine kinase and is thought to play a role in signal transduction in blood cells. Few phosphorylated target proteins for Pim-1, however, have been identified. In the present study, two-hybrid screening to clone cDNAs encoding proteins binding to Pim-1 was carried out, and a cDNA for heterochromatin protein 1gamma (HP1gamma) was obtained. Binding assays both in yeast and in vitro pull-down using the purified HP1gamma and Pim-1 expressed in Escherichia coli showed that Pim-1 directly bound to the chromo shadow domain of HP1gamma. HP1gamma was also associated with Pim-1 in human HeLa cells and the serine clusters located at the center of HP1gamma were phosphorylated by Pim-1 in vitro. Furthermore, a transcription repression activity of HP1gamma was further stimulated by the deletion of the serine clusters targeted by Pim-1. These results suggest that Pim-1 affects the structure or silencing of chromatin by phosphorylating HP1.

Amino Acid Sequence↗

PubMed2000

Sp1 cooperates with c-Myc to activate transcription of the human telomerase reverse transcriptase gene (hTERT).

Telomerase activation is thought to be a critical step in cellular immortalization and carcinogenesis. The human telomerase catalytic subunit (hTERT) is a rate limiting determinant of the enzymatic activity of human telomerase. In the previous study, we identified the proximal 181 bp core promoter responsible for transcriptional activity of the hTERT gene. To identify the regulatory factors of transcription, transient expression assays were performed using hTERT promoter reporter plasmids. Serial deletion assays of the core promoter revealed that the 5'-region containing the E-box, which binds Myc/Max, as well as the 3'-region containing the GC-box, which binds Sp1, are essential for transactivation. The mutations introduced in the E-box or GC-box significantly decreased transcriptional activity of the promoter. Overexpression of Myc/Max or Sp1 led to significant activation of transcription in a cell type-specific manner, while Mad/Max introduction repressed it. However, the effects of Myc/Max on transactivation were marginal when Sp1 sites were mutated. Western blot analysis using various cell lines revealed a positive correlation between c-Myc and Sp1 expression and transcriptional activity of hTERT. Using fibroblast lineages in different stages of transformation, we found that c-Myc and Sp1 were induced to a dramatic extent when cells overcame replicative senescence and obtained immortal characteristics, in association with telomerase activation. These findings suggest that c-Myc and Sp1 cooperatively function as the major determinants of hTERT expression, and that the switching functions of Myc/Max and Mad/Max might also play roles in telomerase regulation.

Base Sequence↗

PubMed2000

Transcription factor Sp1 activates the expression of the mouse tenascin-X gene.

Tenascin-X (TNX) is an extracellular matrix protein that is prominent in the heart and muscle. We previously showed that TNX is expressed in fibroblast cells in culture. To elucidate the molecular basis of the TNX gene expression, the promoter region of the mouse TNX gene (mTnx) has been characterized. The two adjacent transcription initiation sites were identified at 68 and 67 bp upstream of the previously known 5'-untranslated exon. Transient transfection of L and 293T cells with 5'-deletion constructs of the promoter region linked to the luciferase reporter revealed that the region (-141 to -136) containing a transcription factor Sp1-binding element contributes to the expression of mTnx. Site-directed mutagenesis of the Sp1-binding region confirmed this result. Electrophoretic mobility shift analysis using nuclear extracts obtained from the cells demonstrated that a distinct Sp1-DNA complex is formed at the element. Our results show that Sp1 plays a critical role in the gene expression of mTnx.

Animals↗

PubMed2000

MSSP promotes ras/myc cooperative cell transforming activity by binding to c-Myc.

BACKGROUND: MSSPs, myc single strand binding proteins, were originally identified as proteins recognizing a putative replication origin/transcriptional enhancer in the human c-Myc gene. The cDNAs encoding four of the family proteins, MSSP-1, MSSP-2, Scr2 and Scr3, were cloned. These proteins carry two copies of the putative RNA binding domains, RNP-A and RNP-B, and have been suggested to participate in DNA replication and cell cycle progression from the G1 to the S phase. RESULTS: We report that MSSP-1 and MSSP-2 bound directly to the C-terminal portion of c-Myc, along with Max, side by side. MSSP, c-Myc and Max formed a ternary complex in vivo, although MSSP did not directly associate with Max. The MSSP/Myc/Max ternary complex lost the binding activity to the E-box sequence-the recognition sequence of c-Myc/Max complex-thereby abrogating the E-box-dependent transcription activity of c-Myc. MSSP specifically stimulated the cooperative transforming activity of c-myc with ras, in a manner dependent upon the RNP sequences, while mssp itself showed no transforming activity in mouse NIH3T3 cells. The NIH3T3 transformants, together with ras, myc and mssp, grew to form very large colonies in soft agar, as compared to those with ras plus myc or ras alone. CONCLUSIONS: MSSP is a modulator of c-Myc and the c-Myc/MSSP complex may deregulate cell cycle controls and lead cells towards transforming pathways.

3T3 Cells↗

PubMed2000

ORC1 interacts with c-Myc to inhibit E-box-dependent transcription by abrogating c-Myc-SNF5/INI1 interaction.

BACKGROUND: The c-myc oncogene product (c-Myc) is a transcription factor that forms a complex with Max and recognizes the E-box sequence. c-Myc plays key functions in cell proliferation, differentiation and apoptosis. As for its activity towards cell proliferation, it is generally thought that c-Myc transactivates the E-box-containing genes that encode proteins essential to cell-cycle progression. Despite the characterization of candidate genes regulated by c-Myc in culture cells, these have still not been firmly recognized as real target genes for c-Myc. RESULTS: We found that c-Myc directly bound to the N-terminal region of origin recognition complex-1 (ORC1), a region that is responsible for gene silencing, in a state of complex containing other ORC subunits and Max in vivo and in vitro. Furthermore, ORC1 inhibited E-box-dependent transcription activity of c-Myc by competitive binding to the C-terminal region of c-Myc with SNF5, a component of chromatin remodelling complex SNF/Swi1. CONCLUSIONS: These results suggest that ORC1 suppresses the transcription activity of c-Myc by its recruitment into an inactive form of chromatin during some stage of the cell cycle.

Binding, Competitive↗

PubMed2000

Extracellular matrix tenascin-X in combination with vascular endothelial growth factor B enhances endothelial cell proliferation.

BACKGROUND: An extracellular matrix tenascin-X (TNX) is highly expressed in muscular tissues, especially heart and skeletal muscle, and is also prominent around blood vessels. The precise in vivo role of TNX remains to be elucidated. To identify proteins that interact with TNX in the extracellular environment, we searched for TNX-binding proteins using a yeast two-hybrid system. RESULTS: We used mouse TNX-specific fibronectin type III repeats (mTNX/FNIII13-25) as a bait for the screening. We found that vascular endothelial growth factor B (VEGF-B) binds to mTNX/FNIII13-25. This interaction was confirmed by pull-down assays and co-immunoprecipitation assays. The full-length mTNX, as well as mTNX/FNIII13-25, interacted with both alternative splice isoforms VEGF-B186 and VEGF-B167. Furthermore, the full-length mTNX also bound to VEGF-A. The minimal region of TNX that interacts with VEGF-B was mapped to the FNIII repeats (FNIII13-25) but not to the other characteristic domains of TNX. The TNX-binding site of VEGF-B was located in the N-terminal 115-amino acid region. mTNX/FNIII13-25 did not prevent the interaction of VEGF-B with VEGFR-1 (VEGF receptor 1), and VEGF-B could simultaneously bind to both mTNX/FNIII13-25 and VEGFR-1. A conditioned medium from transfected 293T cells coexpressing full-length TNX and VEGF-B could promote DNA synthesis in bovine endothelial cells in which VEGFR-1 were expressed. VEGFR-1 phosphorylation triggered by VEGF-B186 were increased in cells plated with mTNX/FNIII13-25 or full-length mTNX, compared with cells plated with VEGF-B186 alone. CONCLUSION: TNX interacts with VEGF-B and enhances the ability of VEGF-B to stimulate cell proliferation. This enhanced mitogenecity is caused by increased signals mediated by the VEGFR-1 receptor. This finding suggests a role for TNX in the regulation of the development of blood vessels such as vasculogenesis and angiogenesis.

Alternative Splicing↗

PubMed2000

PAP-1, a novel target protein of phosphorylation by pim-1 kinase.

Protooncogene, pim-1, has been reported to be a predisposition for lymphomagenesis along with myc, and its protein product, Pim-1, has been shown to be a serine/threonine protein kinase, whose activity is involved in proliferation and differentiation of blood cells. The signal transduction pathways neither to nor from Pim-1, however, have been clarified. We have cloned a cDNA encoding a novel Pim-1 binding protein, PAP-1, comprising 213 amino acids with a basic amino-acid cluster near the C-terminus. PAP-1 was colocalized with Pim-1 in human HeLa cell nuclei. The in vitro binding assays using GST fusion proteins of the wild-type and various deletion mutants revealed that the whole molecule of Pim-1 is required for the binding activity to PAP-1 and that Pim-1 binds to the region from amino-acid numbers 1-147 of PAP-1, or to two segments in the region. The association of PAP-1 with Pim-1 was also shown in vivo in transfected cells. Furthermore, PAP-1 was phosphorylated in vitro by Pim-1, but not a kinase-negative Pim-1 mutant. The two serine residues of PAP-1 at amino acids 204 and 206 near the C-terminus were phosphorylated by Pim-1. PAP-1 is thus thought to be a target protein for Pim-1 kinase.

Amino Acid Sequence↗

PubMed2000

Extracellular signal regulated protein kinase and c-jun N-terminal kinase are involved in ml muscarinic receptor-enhanced interleukin-2 production pathway in Jurkat cells.

We have previously shown that m1 and m2 muscarinic receptors were expressed on human peripheral blood lymphocytes (hPBL) and that pre-stimulation of these receptors enhanced phytohemagglutinin (PHA)-induced interleukin-2 (IL-2) production. Possible intracellular signal pathways of muscarinic receptors to regulate IL-2 production were examined in human T cell line Jurkat cells. Pretreatment of the cells with muscarinic receptor agonist, oxotremorine M (Oxo-M), enhanced IL-2 production induced by phorbol 12-myristate 13-acetate (PMA)/A23187, while Oxo-M by itself did not affect IL-2 production. The enhancement of IL-2 production by Oxo-M was inhibited by 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) an ml/m3 receptor antagonist. When the cells were pretreated with AF-DX116, an m2 antagonist, the IL-2 production enhanced by Oxo-M was further stimulated. Reverse transcription-polymerase chain reaction (RT-PCR) revealed that ml and m2 muscarinic receptors exist on Jurkat cells. The stimulation of ml receptors enhanced the PMA/A23187-induced binding activity to AP-1 consensus sequences in IL-2 promoter and production of c-Fos and c-Jun protein. The stimulation of ml receptors did not modify the DNA binding of NF-kappaB, NF-AT or Oct-1. When ml receptors were stimulated, activities of mitogen-activated protein kinase (MAPK)/extracellular signal regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK) were increased, while p38 MAPK was not affected. Incubation with Oxo-M induced a transient increase in [Ca2+]i, which was abolished by pretreatment with 4-DAMP. Treatment with cyclosporin A markedly decreased the PMA/A23187-induced IL-2 promoter activity. This treatment, however, did not affect the enhancement of the promoter activity induced by ml receptor stimulation. The results suggest that transcription factor AP-1 is involved in the ml receptor-mediated enhancement of IL-2 transcript in Jurkat cells, and that pathways via MAPK/ERK and JNK, but not via p38 MAPK, are involved in the ml receptor-mediated enhancement of IL-2 promoter activity.

Blotting, Western↗

PubMed2000

Structures and comparison of genomic and complementary DNAs of mouse MSSP, a c-Myc binding protein.

Two cDNAs encoding mouse MSSP and Scr3 were cloned. Both proteins, like those in humans, share significant homology of the region near the N-terminus containing the RNA-binding protein, RNP, while little homology exists near the C-terminal region of the proteins. Expression of mouse MSSP and Scr3 in mouse tissues were examined by Northern blot hybridization and both mRNAs were ubiquitously expressed in all the tissues except for testis, where the smaller sizes of MSSP mRNAs, but not Scr3 mRNA, were highly expressed. Then, the genomic DNA of mouse MSSP was cloned. Mouse genomic MSSP gene was comprised of at least 13 exons over the region spanning 60 kb. Furthermore, a chromosome location of human MSSP gene was identified at 2q24 by FISH mapping.

Amino Acid Sequence↗

PubMed2000

AMY-1 is a trigger for the erythrocyte differentiation of K562 cells.

We have reported that a novel c-Myc binding protein, AMY-1, stimulated the transcription activity of c-Myc and was translocated from cytoplasm to nuclei in a c-Myc-dependent manner. Here, the role of AMY-1 in cell differentiation was examined. AMY-1 expression was up-regulated after differentiation induction of human K562 cells to erythrocyte cells by AraC, while c-Myc expression was rapidly down-regulated. K562 cell lines expressing exogenous AMY-1 were established, and these cells expressed a high level of epsilon-globin mRNA, a marker gene necessary for erythrocyte cell differentiation, without differentiation induction. The addition of AraC rapidly initiated differentiation in these cell lines, which continued to differentiate to erythrocyte cells possessing a high level of hemoglobin even after the decrease in AMY-1 expression. These results suggest that AMY-1 is a trigger for K562 cells to differentiate to erythrocyte cells and that AMY-1 may have a function independent of or different from c-Myc.

Antimetabolites, Antineoplastic↗

PubMed2000

[A questionnaire survey on the self-assessment to the asthmatic treatment in Saitama Prefecture: results from 2825 cases].

The aim of this study was to survey the self-assessment to the treatment of adult bronchial asthmatics in Saitama prefecture. A questionnaire on daily symptoms and medications was distributed to 2825 adult asthmatic subjects who were treated at 125 hospitals/clinics in Saitama prefecture between September 15th and October 30th 1998. More than half (52.7%) of patients described that their general condition of asthma was poorly controlled. Even among the patients described that their condition was good or fair, 30.2% of them had some asthmatic symptoms such as shortness of breath or nocturnal awakening. Although inhaled corticosteroids were used in 66.2%, the ratio of patients who used spacer and kept drug compliance as prescribed were 59.6% and 45.8%, respectively. According to the physician's reports, cysteinyl leukotriene antagonist was used in 35.7%, which was comparable to the total of another anti-allergic drugs (37.3%). These results suggest that more than half of asthmatic patients in Saitama prefecture were not satisfied with their conditions of the disease control. Furthermore, more thorough education on the technique and compliance of inhaled corticosteroids would be required.

Adolescent↗

PubMed1999

Cell cycle-dependent switch of up-and down-regulation of human hsp70 gene expression by interaction between c-Myc and CBF/NF-Y.

A CCAAT box-binding protein subunit, CBF-C/NF-YC, was cloned as a protein involved in the c-Myc complex formed on the G(1)-specific enhancer in the human hsp70 gene. CBF-C/NF-YC directly bound to c-Myc in vitro and in vivo in cultured cells. The CBF/NF-Y.c-Myc complex required the HSP-MYC-B element as well as CCAAT in the hsp70 G(1)-enhancer, while the purified CBF subunits recognized only CCAAT even in the presence of c-Myc. Both the HSP-MYC-B and CCAAT elements were also required for the enhancer activity. In transient transfection experiments, the CBF/NF-Y.c-Myc complex, as well as transcription due to the G(1)-enhancer, was increased by the introduction of c-Myc at low doses but decreased at high doses. The repression of both complex formation and transcription by c-Myc at high doses was abrogated by the introduction of CBF/NF-Y in a dose-dependent manner. Furthermore, the CBF/NF-Y.c-Myc complex bound to the G(1)-enhancer appeared in the early G(1) phase of the cell cycle when c-Myc was not higly expressed and gradually disappeared after the c-Myc expression reached its maximum. The results indicate that the cell cycle-dependent expression of the hsp70 gene is regulated by the intracellular amount of c-Myc through the complex formation states between CBF/NF-Y and c-Myc.

3T3 Cells↗

PubMed1999

Prenatal diagnosis of intrapericardial teratoma: a case report.

A hydropic fetus that exhibited intrapericardial teratoma with marked pericardial effusion was prenatally diagnosed. Intrauterine pericardiocentesis was performed to diagnose and to treat hydrops. Pericardiocentesis for tamponade secondary to a fetal intrapericardial teratoma might prevent fetal death and premature delivery.

Adult↗

PubMed1999

Skin reaction to yellow fever vaccine after immunization with rabies vaccine of chick embryo cell culture origin.

Skin reaction to yellow fever vaccine was examined after immunization with rabies vaccine. The two vaccines contained substrates from chick embryo cells (rabies vaccine) and chick whole embryo (yellow fever attenuated vaccine), as well as gelatin. A prick test with gelatin showed negative results in all vaccinees examined. An intradermal skin test revealed that the yellow fever vaccine had reacted with an anti-egg protein antibody-like substance in a case with a history of egg allergy before rabies vaccination. A case inoculated two times with the rabies vaccine revealed a positive reaction to egg-white protein as well as the yellow fever vaccine. This case had no anamnesis of egg allergy. Thus, an antibody reactive to the egg-white protein and/or the yellow fever vaccine was inducible by the rabies vaccine. The reaction of this antibody was not systemic but local at the skin test by the yellow fever vaccine. The period of the rabies vaccine sensitization reactive to the yellow fever vaccine could be estimated as longer than 14.3 +/- 9.6 days (mean +/- SD), based on a follow-up examination of the positive skin reaction in 41 of 84 cases examined. We therefore conclude that the yellow fever vaccine can be safely administered at an interval of at least four weeks after a second rabies vaccination.

Adult↗