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T Tokino

Publications and source records attributed to T Tokino.

At least 37 records · Page 2Linked to original sources
PubMed2000

A single nucleotide polymorphism in the matrix metalloproteinase-1 promoter in endometrial carcinomas.

Recent studies demonstrated that a single guanine insertion polymorphism in a matrix metalloprotease-1 promoter created an Ets binding site and affected the elevation of the transcriptional level of matrix metalloproteinase-1 (MMP-1). Furthermore, in tumor cell lines derived from melanoma and breast cancer, the incidence of the 2G / 2G genotype was significantly higher than that in the normal population. To evaluate the contribution of this polymorphism in endometrial carcinomas, we genotyped 100 endometrial carcinomas and then analyzed immunoexpression of MMP-1 in these carcinomas. We found that endometrial carcinoma patients showed a significantly higher rate of 1G / 2G or 2G / 2G genotype than control individuals, and that tumors containing the 2G allele(a) expressed MMP-1 protein more frequently than those with 1G / 1G genotype. Therefore, the single nucleotide polymorphism at the MMP-1 promoter affected the expression level of the MMP-1 protein, which may result in the association with more aggressive character in endometrial carcinoma. Our result suggests that the presence of 2G polymorphism at the MMP-1 promoter may be one of the risk factors for the development and / or progression of endometrial carcinoma.

Base Sequence↗
PubMed2000

Induction of cellular genes is mediated by the Bel1 transactivator in foamy virus-infected human cells.

To gain insight into human foamy virus (HFV; also called spumaretrovirus)-induced alterations of cellular genes, the expression profiles of defined genes in HFV-infected primary human cells were analyzed by cDNA array assays. Several distinct cellular genes activated by HFV infection were identified; the identities of the cellular genes were confirmed by RNA blot analyses. Compared with mock-infected controls, the concentrations of cellular Kip2, Egr-1, COUP-TF1, insulin-like growth factor II (IGF-II), and EphB3 mRNAs were significantly increased in HFV-infected cells and showed a gene-specific and time-dependent induction. Immunoblot analyses with antibodies against some of the cellular gene products revealed increased levels of the corresponding proteins. To investigate mechanisms of HFV-induced alterations in cellular gene expression, the capacity of known HFV genes to increase expression of defined cellular genes was analyzed by transient expression experiments. Plasmids that encode the HFV Bel1 transcriptional transactivator were necessary and sufficient to strongly increase expression of p57Kip2, IGF-II, and EphB3 genes in 293T cells. Potential mechanisms and consequences of activation of cellular genes during HFV infection and Bel1 transactivation of the Kip2 gene are discussed.

Blotting, Northern↗
PubMed1999

Localization of membrane-associated guanylate kinase (MAGI)-1/BAI-associated protein (BAP) 1 at tight junctions of epithelial cells.

Membrane-associated guanylate kinase (MAGI)-1/BAI-associated protein (BAP) 1 and Synapse-associated protein (SAP) 97/human Discs-large tumor suppressor gene (hDLG) are ubiquitous isoforms of synaptic scaffolding molecule (S-SCAM) and Postsynaptic density (PSD)-95/SAP90, both of which are implicated in the structures of synapses, respectively. SAP97/hDLG is localized at epithelial junctions and may function as a scaffolding protein, but the subcellular localization or the function of MAGI-1/BAP1 has not been clarified. In intestinal epithelial cells, MAGI-1/BAP1 was localized at tight junctions, whereas SAP97/hDLG was localized diffusely at cell - cell junctions. In Madine Darby canine kidney (MDCK) cells, MAGI-1/BAP1 was colocalized with ZO-1, whereas SAP97/hDLG was colocalized with E-cadherin. In MDCK cells, dominant active and negative mutants of Rac1 small G protein changed the amounts of SAP97/hDLG at cell - cell junctions, but not that of MAGI-1/BAP1. When MDCK cells were switched to a low Ca2+ medium, E-cadherin disappeared from the plasma membrane, and cells were dissociated. The phorbol 12-myristate 13-acetate-treatment after the low Ca2+ switch induced a tight junction-like structure. MAGI-1/BAP1 was recruited with ZO-1 to this structure, but SAP97/hDLG or E-cadherin was not. These findings suggest that MAGI-1/BAP1 is a component of tight junctions of epithelial cells, and that its role is different from that of SAP97/hDLG.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Molecular cloning, mapping, and characterization of a novel human gene, MTA1-L1, showing homology to a metastasis-associated gene, MTA1.

Through large-scale sequencing of clones randomly selected from libraries of human cDNAs, we have isolated a novel human gene encoding a product with 59.6% identity in amino acid sequence to human MTA1, a protein associated with tumor invasion and metastasis. This cDNA, named MTA1-L1 (MTA1 like 1), consists of 2736 nucleotides with an open reading frame encoding 668 amino acids. A single 3.0-kb transcript of MTA1-L1 was expressed ubiquitously on Northern blots. Structural analysis of the MTA1-L1 gene revealed 18 exons spanning 8.1 kb of genomic DNA. We assigned the MTA1-L1 locus to chromosomal band 11q12-13.1 by fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed1999

Retrovirus vectors designed for efficient transduction of cytotoxic or cytostatic genes.

It is difficult to establish stable packaging cell lines producing retrovirus vectors for the expression of anti-oncogenes with cytotoxic or cytostatic potential, because these genes would also affect the growth of the packaging cell lines. To overcome this problem, we designed a transcriptional unit pBabeLPL for vector RNA production, in which the transcription of the exogenous genes is completely suppressed by the presence of a preceding insertion containing the puromycin resistance gene (puro) and a poly(A) addition signal. This insertion is flanked by a tandem pair of loxP, and is designed to be excised after the introduction of Cre recombinase, when transcription of the exogenous gene will be started from the 5'-LTR. The transcriptional unit car- rying LacZ or p53 as the exogenous gene was introduced into a previously constructed prepackaging cell lines PtG-S2, in which the expression of VSV-G is also designed to be initiated by the introduction of Cre recombinase, while the gag-pol gene is expressed continuously. After the introduction of Cre recombinase by an adenovirus vector, LacZ- or p53-expressing VSV-G-pseudotyped retrovirus vectors with the designed structure were produced at high virus titers. The p53 virus was shown to be able to transduce p53 into the entire population of several human cancer cell lines and to induce their growth arrest at the G1 phase, indicating that this vector-producing system will be advantageous for human gene therapy.

Adenoviridae↗
PubMed1999

Mutations of the beta-catenin gene in endometrial carcinomas.

To investigate the contribution of beta-catenin to the development of endometrial carcinoma, we searched for genetic alterations of the beta-catenin gene in primary endometrial carcinomas. Mutational analysis of exon 3 of the beta-catenin gene, encoding the serine/threonine residues for GSK-3 beta phosphorylation, was performed for 35 tumors. Nucleotide sequencing analysis revealed that 5 tumors (5/35, 14%) contained mutations (S33C, S37C, S37F, T41A) that altered potential GSK-3 beta phosphorylation sites. Each of the mutations resulted in the substitution of serine/threonine residues that have been implicated in the down-regulation of beta-catenin through phosphorylation by GSK-3 beta kinase. Furthermore, the incidence of beta-catenin mutations was significantly higher in early-onset (3 of 5) than that in late-onset tumors (2 of 30) (P = 0.014, Fisher's exact test). Replication error (RER)-positive phenotype was not detected in tumors with the beta-catenin gene mutation, although 10 of 35 tumors revealed RER. We performed immunohistochemistry of beta-catenin in 17 cases for which tissue samples were available. We confirmed accumulation of beta-catenin protein in both the nucleus and cytoplasm in 3 tumors, including two in which amino acid alterations had occurred at codon 33 and 37. The other case had no mutation in exon 3. Our results suggested that mutations at serine/threonine residues involved in phosphorylation by GSK-3 beta affected the stability of beta-catenin. Accumulation of mutant beta-catenin could contribute to the development of a subset of endometrial carcinomas, particularly those of the early-onset type.

Amino Acid Substitution↗
PubMed1999

Mutational analysis of beta-catenin gene in Japanese ovarian carcinomas: frequent mutations in endometrioid carcinomas.

To investigate the contribution of the beta-catenin gene to the development of ovarian carcinomas, mutational analysis of exon 3 of the beta-catenin gene was conducted. We analyzed 61 primary ovarian carcinomas, consisting of 49 non-endometrioid-type and 12 endometrioid-type tumors, for genetic alteration of the beta-catenin gene. Five carcinomas showed beta-catenin mutations (S37C, T41I, T41A), including 4 (33%) of 12 endometrioid-type tumors and 1 (14%) of 7 mucinous-type tumors. All of these mutations altered at the serine/threonine residues that are potential sites of GSK3-beta phosphorylation. We detected no carcinomas with interstitial deletion involving exon 3 of beta-catenin. Furthermore, we immunohistochemically studied 27 of the 61 ovarian carcinomas. Both nuclear and cytoplasmic beta-catenin expressions were demonstrated in 4 of the 27 ovarian carcinomas for which tissue samples were available for examination. All 4 cases exhibited mutations in exon 3 of beta-catenin, including a mucinous carcinoma. Our results suggested that beta-catenin gene mutation at potential GSK3-beta phosphorylation sites results in accumulation of beta-catenin protein within the cells and its translocation to nuclei. Accumulated beta-catenin protein may be involved in the development of endometrioid-type ovarian carcinomas, and some mucinous-type ovarian carcinomas.

Adult↗
PubMed1999

Mutational analysis of STK11 gene in ovarian carcinomas.

Recently STK11, the causative gene of Peutz-Jeghers syndrome (PJS) was identified on chromosome 19p13.3. PJS is often accompanied by several malignancies, including breast tumor, adenoma malignum of the uterine cervix, and ovarian tumor. To investigate the involvement of STK11 gene in the development of ovarian carcinomas, we analyzed 30 ovarian carcinomas for loss of heterozygosity (LOH) and STK11 gene mutations. We found one missense mutation (codon 281, Pro to Leu) with heterozygous and somatic status. This mutation occurred at codon 281, which lies within the mutational hot spot (codon 279-281) of STK11 gene previously reported in PJS. We also detected LOH in 2 (11%) of 19 informative ovarian carcinomas. Our results suggest that mutations of the STK11 gene may play a limited role in the development of ovarian carcinomas.

AMP-Activated Protein Kinase Kinases↗
PubMed1999

Induction of transformation and p53-dependent apoptosis by adenovirus type 5 E4orf6/7 cDNA.

Adenovirus (Ad) E4orf6/7, one of the early gene products of human Ads, forms a stable complex with the cellular transcription factor E2F to activate transcription from the Ad E2 promoter. E2F cDNAs have growth-promoting and apoptosis-inducing activities when overexpressed in cells. We cloned Ad5 E4orf6/7 cDNA in both simian virus 40- and human cytomegalovirus-based expression vectors to examine its transforming and apoptotic activities. The cloned E4orf6/7 collaborated with a retinoblastoma protein (RB)-nonbinding and therefore E2F-nonreleasing mutant of Ad5 E1A (dl922/947) to morphologically transform primary rat cells, suggesting that E2F is an important cellular protein functioning downstream of E1A for transformation. In a G418 colony formation assay, E4orf6/7 was shown to suppress growth of untransformed rat cells. Moreover, a recombinant Ad expressing Ad5 E4orf6/7 induced apoptosis in rat cells when coinfected with wild-type p53-expressing Ad. Mutational analysis of E4orf6/7 revealed that both of the domains required for growth inhibition and transformation by E4orf6/7 lay in the C-terminal region, which is essential for transactivation from the upstream sequence of an E2a promoter containing E2F-binding sites. However, the smallest mutant of E4orf6/7, encoding the C-terminal 59 amino acids, failed to complement the RB-nonbinding dl922/947 mutant despite showing growth inhibition and E2F transactivation activities. Thus, it is suggested that a subregion of E4orf6/7 which is required for growth inhibition and transformation in collaboration with dl922/947 overlaps the transactivation domain of E4orf6/7.

Adenovirus E1A Proteins↗
PubMed1999

Identification of BAIAP2 (BAI-associated protein 2), a novel human homologue of hamster IRSp53, whose SH3 domain interacts with the cytoplasmic domain of BAI1.

BAI1 (brain-specific angiogenesis inhibitor 1) was originally isolated as a p53-target gene specifically expressed in brain. To clarify its function, we have been searching for cellular proteins that associate with the cytoplasmic domain of BAI1. Using its intracellular carboxyl terminus as "bait" in a yeast two-hybrid system, we isolated a cDNA clone named BAIAP2 whose nucleotide sequence would encode a 521-amino acid protein showing significant homology to a 58/53-kDa substrate of insulin-receptor kinase in the hamster. As the expression profile of BAIAP2 examined by Northern blot analysis was almost identical to that of BAI1, BAIAP2 appears to be active mainly in neurons. In vitro binding assays confirmed that a proline-rich cytoplasmic fragment of BAI1 interacted with the Src homology 3 (SH3) domain of BAIAP2. Double-color immunofluorescent analysis revealed that BAIAP2 was localized at the cytoplasmic membrane when it was coexpressed with BAI1 in COS-7 cells; BAIAP2 not associated with BAI1 was diffused in the cytoplasm. Predominant localization of BAI1 protein in a sub-cellular fraction enriched in growth cones indicated a possible role of BAI1 as a cell adhesion molecule inducing growth cone guidance. As a protein partner of BAI1, BAIAP2 may represent an important link between membrane and cytoskeleton in the process of neuronal growth.

Amino Acid Sequence↗
PubMed1999

Recombinant adenovirus expressing wild-type p53 is antiangiogenic: a proposed mechanism for bystander effect.

Angiogenesis is required for the growth and progression of malignancies. Recent studies have demonstrated that genetic alterations may accompany acquisition of the angiogenic phenotype. The tumor suppressor gene p53 is most frequently mutated in human cancers and is also known to be a transcriptional regulator of a variety of genes. Here, we investigated the antiangiogenic effect of the wild-type p53 (wt-p53) gene transfer on a human non-small cell lung cancer cell line. Mutant p53-expressing H226Br non-small cell lung cancer cells were transduced with the wt-p53 gene using a recombinant adenoviral vector (Ad5CMVp53) and applied to semiquantitative reverse transcription-PCRs for the detection of altered mRNA expression of angiogenic and/or antiangiogenic factors. In vivo neovascularization assay of Ad5CMVp53-infected cells was then performed using a membrane-diffusion chamber system s.c. transplanted in nu/nu mice. We also evaluated the effect of Ad5CMVp53-infected H226Br cells on nontransduced tumor cells in vivo by s.c. inoculating mixture of cells into nu/nu mice. Ad5CMVp53 infection markedly inhibited the expression of an angiogenic factor, vascular endothelial growth factor, and increased the expression of a novel antiangiogenic factor, brain-specific angiogenesis inhibitor 1, resulting in reduced neovascularization in vivo. Mixing experiments showed that tumor cells transduced with the wt-p53 gene inhibited the in vivo tumor growth of adjacent nontransduced cells. Our data suggest that a recombinant adenovirus expressing the wt-p53 gene is antiangiogenic, which may explain, in part, the mechanism of the bystander effect induced by the wt-p53 gene transfer on adjacent tumor cells.

Adenoviruses, Human↗
PubMed1999

Induction of apoptosis in T98G glioblastoma cells by transfection of GML, a p53 target gene.

Expression of the glycosyl-phosphatidylinositol-anchored molecule-like protein (GML) gene, a p53 target, correlates with the sensitivity of some cancer cell lines to anticancer drugs and ionizing radiation. To investigate the function of GML further, we introduced the GML cDNA into various cancer cell lines under control of the tetracycline-regulated system. When we introduced GML into human glioblastoma cell line T98G, which lacks wild-type p53 and expresses no endogenous GML, we observed significant growth suppression accompanied by G2/M arrest in two independent, stable cell lines. We confirmed induction of apoptosis by fluorescence-activated cell sorting (FACS) analysis and nuclear staining. Our results indicated that GML could induce apoptosis of T98G without functional p53, and implied that GML plays a crucial role in the apoptotic pathway in some cancer cells.

Apoptosis↗
PubMed1999

Significant increase of adenovirus infectivity in glioma cell lines by extracellular domain of hCAR.

Recombinant adenoviruses are highly advantageous as vectors for transferring genes into mammalian cells, but the transfer is not efficient in all types of cells. We investigated the effects of four adenoviral receptors [integrinalphav, integrinbeta3, integrinbeta5, and human coxsackievirus and adenovirus receptor (hCAR)] on adenovirus-mediated transfer of exogenous cDNA into each of 10 glioma cell lines. Transfection efficiency varied widely from one cell line to another (0-100%) when we measured it by infection with AdLacZ, a vector designed to express beta-galactosidase. Levels of integrinalphav and integrinbeta5 expression were similar among the 10 cell lines, but expression of hCAR and integrinbeta3 varied significantly. As these observations indicated a possible correlation between expression of hCAR and the efficiency of gene transfer, we induced the hCAR gene into three glioma cell lines (T98G, U118MG, and U138MG) that expressed hCAR at very low levels and had also revealed low efficiencies of adenoviral gene transfer. In U118MG- and U138MG-derived cells that had regained the ability to express hCAR in stable fashion, adenovirus-mediated gene transfer became highly efficient. Moreover, addition of the peptide corresponding to the extracellular domain of hCAR (ECD-hCAR) by preincubation significantly increased the adenovirus infectivity to these adenovirus-tolerant cells. These results suggest that hCAR could be one of important determinants of the infectivity of adenovirus, and that the ECD-hCAR might be a novel useful tool for improvement of adenovirus-mediated gene therapy against the adenovirus-tolerant cancer cells.

Adenoviridae↗
PubMed1998

Cloning and characterization of BAP3 (BAI-associated protein 3), a C2 domain-containing protein that interacts with BAI1.

BAI1 (brain-specific angiogenesis inhibitor 1), a p53-target gene specifically expressed in brain, encodes a seven-span transmembrane protein considered to be a member of the secretin receptor family. Using a two-hybrid system, we isolated a cDNA encoding a product that interacts with the cytoplasmic region of BAI1 and designated it BAP3 (BAI1-associated protein 3). The BAP3 product is a novel C2 domain-containing molecule with homology to Munc13 and synaptotagmin. As with Munc13, BAP3 is expressed predominantly in brain. Deletion-mutant analysis revealed that the interaction between BAI1 and BAP3 was not mediated by the C2 domains. Its predominant expression in brain and homology to Munc13 indicate that BAP3, by interacting with BAI1, might be involved in some neuronal function such as regulating release of neurotransmitters.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Cloning and characterization of BAI-associated protein 1: a PDZ domain-containing protein that interacts with BAI1.

Brain-specific angiogenesis inhibitor 1 (BAI1), which is a p53-target gene specifically expressed in brain, encodes a seven-span transmembrane protein. Using a two-hybrid system, we isolated a cDNA that encodes a protein, named BAP1 (BAI1-associated protein), which interacts with the cytoplasmic region of BAI1. BAP1 is a novel member of the MAGUK (membrane-associated guanylate kinase homologue) family; it possesses a guanylate kinase domain, WW domains, and multiple PDZ domains. Interaction between BAI1 and BAP1 was mediated by a QTEV motif in the carboxy-terminal region of BAI1 and PDZ domains of BAP1. By immunocytochemical analysis of COS-7 cells transfected with BAI1 and BAP1, both products were co-localized at the cytoplasmic membrane, especially at cell-cell junctions. Cells transfected with BAI1 formed filopodia-like cytoplasmic extensions. These results suggest that BAI1 and BAP1 might be involved in cell adhesion and signal transduction in brain.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Cloning and characterization of the murine P2XM receptor gene.

We have isolated the murine counterpart of the human P2XM gene (mP2XM), a P2X purinoceptor that is expressed predominantly in skeletal muscle. The mP2XM gene, consisting of 12 exons that span 10 kb of genomic DNA, encodes a 379-amino-acid product with 83% identity to the human homologue. Two potential transmembrane domains (M1 and M2) are present in the predicted product, and a segment resembling the H5 region of voltage-gated ion channels is completely conserved between human and mouse P2XM proteins. Predominant expression of mP2XM in murine skeletal muscle was confirmed by Northern-blot analysis, and a low level of expression was detectable in lung tissue, although human lung does not express P2XM.

Amino Acid Sequence↗
PubMed1998

CSR, a scavenger receptor-like protein with a protective role against cellular damage causedby UV irradiation and oxidative stress.

Oxidative stress is a pathogenic condition that causes cellular damage and, in a normally functioning cell, several transcription factors respond to this threat by modulating expression of genes whose products ameliorate the altered redox status in some way. We have isolated a novel macrophage scavenger receptor-like gene, CSR (cellular stress response), whose transcription in normal fibroblasts was significantly elevated by exposure to UV radiation or hydrogen peroxide, and pre-treatment with antioxidants prevented induction of CSR . Under conditions of oxidative stress, reactive oxygen species were significantly depleted in CSR -overexpressing cells, indicating that the CSR product protects cells by scavenging oxidative molecules or harmful products of oxidation. Further investigations into the regulation and function of CSR should open a way to understanding the cellular response and the pathogenic processes caused by oxidative stress.

Amino Acid Sequence↗