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T Kozu

Publications and source records attributed to T Kozu.

At least 19 recordsLinked to original sources
PubMed1996

Designing of chimeric DNA/RNA hammerhead ribozymes to be targeted against AML1/MTG8 mRNA.

For therapeutic purposes, two chimeric DNA/RNA hammerhead ribozymes were synthesized to cleave AML1/MTG8, the t(8;21)-associated fusion mRNA of acute myeloid leukemia. One ribozyme, A/MRZ-1, recognizes the area adjacent to the fusion point between AML1 and MTG8, and cleaves six bases downstream from this point. The other, MRZ-1, recognizes the MTG8 sequence. Both ribozymes cleaved synthetic chimeric DNA/RNA substrates at theoretical sites. Neither cleaved AML1 RNA. A/MRZ-1 cleaved only AML1/MTG8 RNA, and MRZ-1 cleaved both AML1/MTG8 and MTG8 RNAs. The two ribozymes showed growth inhibition of an acute myeloid leukemia cell line carrying t(8;21), SKNO-1 cells. The same extent of growth inhibition was attained by antisense oligonucleotides against AML1/MTG8 RNA. The results suggest that the ribozyme has the potential to be developed as a useful agent for gene therapy, in particular for leukemia with t(8;21).

Antineoplastic Agents↗
PubMed1995

Structure and expression of the gene (HNRPA2B1) encoding the human hnRNP protein A2/B1.

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a major nuclear protein and one of the major components of the hnRNP core complex in mammalian cells. We first determined the complete sequence of the human gene for hnRNP protein A2 (HNRPA2B1). The human HNRPA2B1 gene exists in a single copy over 9 kb in length. The gene was split into 12 exons, including a 36-nucleotide mini-exon, which was specific to the hnRNP protein B1, providing genetic evidence that the B1 mRNA was generated from the primary HNRPA2B1 transcript by alternative splicing. The 5' region of HNRPA2B1 was GC-rich and contained several DNA motifs for the binding of several transcription factors, which included 2 CCAAT boxes and no TATA sequences. The 5' ends of the mRNA were mapped to multiple positions. These structural features are characteristic of promoter regions of housekeeping genes. Northern blot and RT-PCR analyses of the HNRPA2B1 transcripts revealed levels of B1 mRNA from 2 to 5% of total A2/B1 transcripts and showed that both A2 and B1 mRNAs were transcribed in all human cell lines and mouse tissues studied. The structural and evolutionary characteristics of the A2 and A1 proteins as they relate to each other are discussed.

Amino Acid Sequence↗
PubMed1995

Disappearance of AML1-MTG8(ETO) fusion transcript in acute myeloid leukaemia patients with t(8;21) in long-term remission.

In a study of 23 patients with t(8;21)-associated acute myeloid leukaemia the AML1-MTG8 fusion transcript was present in the majority of serial samples obtained from 17 patients followed for up to 34 months after diagnosis, but was absent in samples from all six patients who had been in continuous complete remission for 61 months after allogeneic bone marrow transplantation (BMT), or for 52, 53, 123, 182 and 198 months, respectively, after courses of intensive chemotherapy. Previous studies showed that the AML1-MTG8 fusion transcript was present in most patients with this type of translocation in long-term remission. Our results indicate that blood cells of patients with t(8;21) in remission of over 10 years may not show the AML1-MTG8 fusion transcript, and that those of patients who have undergone allogeneic BMT or intensive chemotherapy may become fusion transcript-negative much earlier. Our study suggests that leukaemic cells with the AML1-MTG8 fusion transcript may survive for some time after courses of chemotherapy or BMT, but that they may eventually be eradicated by immunologic and other antileukaemic mechanisms.

Acute Disease↗
PubMed1995

Pancreatic development and anatomical variation.

The pancreas is formed by the fusion of the ventral and dorsal anlage, and a wide spectrum of anomalies or anatomical variations may appear related to this complicated process of fusion: e.g., agenesis, aplasia of a pancreatic anlage, hypoplasia, annular pancreas, pancreas divisum or nonfusion of the ventral and dorsal duct system, pancreaticobiliary maljunction, etc. Every endoscopist who engages in pancreatography or related diagnostic and therapeutic procedures should always be aware of all sorts of anatomical variations he or she might encounter.

Aged↗
PubMed1993

Junctions of the AML1/MTG8(ETO) fusion are constant in t(8;21) acute myeloid leukemia detected by reverse transcription polymerase chain reaction.

The chromosomal translocation, t(8;21), is found frequently in acute myeloid leukemia (AML) with maturation (FAB-M2). We have previously mapped the translocation breakpoints of t(8;21) in a specific intron of the AML1 gene on chromosome 21. In this study, we cloned cDNAs synthesized from a cell line carrying t(8;21) by reverse transcription polymerase chain reaction (RT-PCR) using an AML1-specific primer. The analysis of the cDNAs structure has led to the identification of the fusion of AML1 with a gene named MTG8 on chromosome 8, which seems to be identical to ETO. Northern analysis using MTG8 (ETO) probes detected 7.8-kb and 6.2-kb RNAs and several minor RNAs in the cell line with t(8;21), but failed to detect any transcripts in a cell line without t(8;21). A set of primers were designed to detect the AML1/MTG8(ETO) fusion by PCR. The PCR amplified identical products in all 6 patients and one cell line with t(8;21), suggesting that the AML1/MTG8(ETO) fusion is a constant feature associated with t(8;21) and the junctions of the AML1/MTG8(ETO) fusion are restricted in a unique site. Because the PCR detection of the AML1/MTG8(ETO) fusion at the RNA level is highly sensitive, it can be used as a sensitive method for diagnosis and detection of minimal residual disease in t(8;21) leukemia.

Amino Acid Sequence↗
PubMed1993

The t(8;21) translocation in acute myeloid leukemia results in production of an AML1-MTG8 fusion transcript.

The t(8;21) translocation is one of the most frequent chromosome abnormalities in acute myeloid leukemia. It has been shown that the t(8;21) breakpoints on chromosome 21 cluster within a single specific intron of the AML1 gene, which is highly homologous to the Drosophila segmentation gene runt. Here we report that this translocation juxtaposes the AML1 gene with a novel gene, named MTG8, on chromosome 8, resulting in the synthesis of an AML1-MTG8 fusion transcript. The fusion protein predicted by the AML1-MTG8 transcript consists of the runt homology region of AML1 and the most part of MTG8, which contains putative zinc finger DNA binding motifs and proline-rich regions constituting a characteristic feature of transcription factors. The MTG8 gene is not expressed in normal hematopoietic cells, whereas AML1 is expressed at high levels. Our results indicate that the production of chimeric AML1-MTG8 protein, probably a chimeric transcription factor, may contribute to myeloid leukemogenesis.

Acute Disease↗
PubMed1992

Consistent disruption of the AML1 gene occurs within a single intron in the t(8;21) chromosomal translocation.

The AML1 gene on chromosome 21 was rearranged by the t(8;21) chromosomal translocation in acute myeloid leukemia (AML). Southern blot analysis of 21 AML patients with t(8;21), including three with complex translocations, t(8;V;21), demonstrated that all the breakpoints occurred at random within a single intron between two coding exons of AML1. Clustering of the breakpoints in the restricted intron suggests the formation of a unique fusion gene between the AML1 gene and a presumable counterpart gene on chromosome 8. Nucleotide sequencing of the breakpoint region revealed that the translocation event was accompanied by deletion of a short stretch of nucleotides.

Base Sequence↗
PubMed1992

[A cases of antithrombin III (ATIII) deficiency associated with extrahepatic portal occlusion undergoing operation for esophgogastric varices].

A 23-year-old woman developed thrombosis of the superior mesenteric vein and underwent an extensive enterectomy. She was diagnosed to have ATIII deficiency with extrahepatic portal vein thrombosis and esophagogastric varices. She was admitted to our department and underwent esophageal mucosal transection and splenectomy. Her activities of ATIII were 46%, but ATIII activities of her family were over 90%. ATIII activities during perioperative period were kept more than 70% following administration of ATIII drug. After splenectomy thrombocythemia which was over 300 x 10(4)/mm3 appeared with severe headache and slight pain of hands. She was discharged on 76th postoperative day with no complications and collapse of esophageal varices.

Adult↗
PubMed1991

t(8;21) breakpoints on chromosome 21 in acute myeloid leukemia are clustered within a limited region of a single gene, AML1.

The t(8;21)(q22;q22) translocation is a non-random chromosomal abnormality frequently found in patients with acute myeloid leukemia (AML) with maturation (M2 subtype). We report here the cloning of a gene, named AML1, on chromosome 21 that was found to be rearranged in the leukemic cell DNAs from t(8;21) AML patients. The breakpoints in 16 out of 21 patients were clustered within a limited region of AML1, and detailed analysis in 3 patients revealed that the breakpoints occurred in the same intron of the gene. Sequencing of cDNA clones identified a long open reading frame encoding a 250-amino acid protein. Northern blot analysis detected four constant mRNA species in t(8;21) leukemic and normal cells; the largest species was more abundant in the leukemic cells than in normal cells. In addition, two mRNA species limited to the leukemic cells were found. These findings indicate that the AML1 gene may be involved in neoplastic transformation of AML with the t(8;21) translocation.

Acute Disease↗
PubMed1990

Structure of DNA polymerase alpha-primase complexes from mammalian cells analyzed by using monoclonal antibodies.

The molecular masses of two of the four DNA polymerase alpha-primase complex subunit peptides from various mammalian cells have been compared through the use of specific monoclonal antibodies. One monoclonal antibody (E4) binds to 77-kDa peptide from HeLa cells and cognate peptides from other mammalian cells (monkey, mouse, bovine, Indian muntjac, and hamster). Another monoclonal antibody (A5) binds the 180-kDa type peptide and its degradation product (160-kDa peptide) of the mammalian DNA polymerase alpha-primase complexes. Neither of these antibodies reacts with DNA polymerase alpha-primase complex from chicken cells. Comparative immunoblot analysis indicates that the molecular masses of the two main peptides of DNA polymerase alpha-primase complex isolated from the various mammalian sources are in excellent agreement with each other, except for the 77-kDa type peptide from bovine and Indian muntjac cells which was found to be significantly smaller (68 kDa) in these cases. The small molecular mass of bovine 77-kDa type peptide is not attributable to the action of a protease which may be present in the extract of bovine cells.

Animals↗
PubMed1990

[A case of fatal graft-versus-host disease following blood transfusion in esophageal cancer documented by homozygous changes of HLA typing].

A 72 year-old Japanese male with esophageal cancer underwent esophagectomy. After seemingly uneventful recovery, he developed high fever on 11 post-operative day (POD), rashes over the whole body on 13 POD and leukopenia on 15 POD. On 22 POD, thrombopenia and parenchymal bleeding of lungs were noted. He died on 26 POD after progressive hypoxia and hypotension. HLA type of peripheral lymphocytes on him changed homozygously to that of the transfused fresh blood. Skin biopsy showed mild leukocyte infiltration in the epidermis and the dyskeratotic keratinocytes were associated with a contiguous lymphocyte, the so-called satellite cell necrosis. In the findings of autopsy, aplastic bone marrow and atrophied spleen, whose weight was 14g, were noted. Based on the clinical picture, skin biopsy and HLA study findings, we diagnosed this case as post-transfusion GVHD. We think that high age, operative injury and preoperative irradiation might be inducement to reveal post-transfusion GVHD in this case.

Aged↗
PubMed1988

[Problems in therapy of thoracic esophageal cancer in view of recurrence in the lymph nodes].

The forms of recurrence from the first onset were confirmed in 171 out of 776 patients with thoracic esophageal cancer excised at our Department from 1959 to 1987; 87 patients (50.9%) had recurrence in the lymph nodes. Postoperative radiation in order to prevent recurrence in the lymph nodes was useful for the prevention of recurrence in the cervical lymph nodes, but radiation myelopathy/radiation pneumonitis might be of therapeutic difficulty in patients with recurrence in the areas of radiation. Moreover, patients treated by irradiation were apt to be involved in visceral recurrence. Incidence of recurrence in the lymph nodes was less in patients who had dissection in three areas than that in patients who received dissection in one or two. However, recurrence was observed in the border region between the cervix and the thorax, on the left side of the trachea, in the anterior portion and on the left side of the hilum in the areas of dissection. Useful postoperative chemotherapy is desirable in consideration of the fact that recurrence in the lymph nodes was observed at the posterior region of the pharynx, at the temporal region and in the pelvis and that dissemination and visceral recurrence were increased.

Combined Modality Therapy↗
PubMed1987

Immunochemical detection of a primase activity related subunit of DNA polymerase alpha from human and mouse cells using the monoclonal antibody.

A hybrid cell line (HDR-854-E4) secreting monoclonal antibody (E4 antibody) against a subunit of human DNA polymerase alpha was established by immunizing mice with DNA replicase complex (DNA polymerase alpha-primase complex) prepared from HeLa cells. The E4 antibody immunoprecipitates DNA replicase complex from both human and mouse cells. The E4 antibody neutralizes the primase activity as assessed either by the direct primase assay (incorporation of [alpha-32P]AMP) or by assay of DNA polymerase activity coupled with the primase activity using unprimed poly(dT) as a template. The E4 antibody does not neutralize DNA polymerase alpha activity with the activated calf thymus DNA as a template. Western immunoblotting analysis shows that the E4 antibody binds to a polypeptide of 77 kilodaltons (kDa) which is tightly associated with DNA polymerase alpha. The 77-kDa polypeptide was distinguished from the catalytic subunit (160 and 180 kDa) for DNA synthesis which was detected by another monoclonal antibody, HDR-863-A5. Furthermore, it is unlikely that the 77-kDa peptide is the primase, since we found that the E4 antibody also immunoprecipitates the mouse 7.3S DNA polymerase alpha which has no primase activity, and Western immunoblotting analysis shows that the 77-kDa polypeptide is a subunit of the 7.3S DNA polymerase alpha. Furthermore, after dissociation of the primase from mouse DNA replicase by chromatography on a hydroxyapatite column in the presence of dimethyl sulfoxide and ethylene glycol, the 77-kDa polypeptide is associated with DNA polymerase alpha, and not with the primase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Activity levels of mouse DNA polymerase alpha-primase complex (DNA replicase) and DNA polymerase alpha, free from primase activity in synchronized cells, and a comparison of their catalytic properties.

To asses the possible roles of the two active forms of mouse DNA polymerase alpha: primase--DNA-polymerase alpha complex (DNA replicase) and DNA polymerase alpha free from primase activity (7.3S polymerase), in nuclear DNA replication the correlation of their activity levels with the rate of nuclear DNA replication was determined and a comparison made of their catalytic properties. The experiments using either C3H2K cells, synchronized by serum starvation, or Ehrlich culture cells, arrested at the S phase by aphidicolin, showed DNA replicase to increase in cells in the S phase to at least six times that of the G0-phase cells but 7.3S polymerase to increase but slightly in this phase. This increase in DNA replicase activity most likely resulted from synthesis of a new enzyme, as shown by experiments using a specific monoclonal antibody, aphidicolin and cycloheximide. Not only with respect to the presence or absence of primase activity, but in other points as well the catalytic properties of these two forms were found to differ; DNA replicase preferred the activated calf thymus DNA with wide gaps of about 100 nucleotides long as a template-primer, while the optimal gap size for 7.3S polymerase was 40-50 nucleotides long. Size analysis of the products synthesized on M13 single-stranded circular DNA with a single 17-nucleotide primer by DNA replicase and 7.3S polymerase suggested the ability of DNA replicase to overcome a secondary structure formed in single-stranded DNA to be greater than that of 7.3S polymerase.

Animals↗
PubMed1986

Size difference in catalytic polypeptides of two active forms of mouse DNA polymerase alpha and separation of the primase subunit from one form, DNA replicase.

There are two active forms of DNA polymerase alpha in mouse cells. One form (DNA replicase) is a DNA polymerase associated with primase activity and the other form (7.3 S polymerase) has no primase activity (Yaugar, T., Kozu, T. and Seno, T. (1982) J. Biol. Chem. 257, 11121-11127). The primase activity was dissociated from partially purified DNA replicase by hydroxyapatite column chromatography in buffer containing dimethyl sulfoxide and ethylene glycol. Nearly homogeneous primase, consisting of a 58 kDa polypeptide was obtained by glycerol gradient sedimentation and DEAE-cellulose column chromatography. Experiments on the effect of proteinase treatment and measurement of the molecular weight of the catalytic polypeptide of DNA replicase after its dissociation from the primase polypeptide indicated that the primase is not part of the DNA polymerase molecule, but an independent protein associated with DNA polymerase alpha, and that the latter is a 115 kDa catalytic polypeptide. The other form of DNA polymerase alpha, 7.3 S polymerase, consists of a 72 kDa catalytic polypeptide. Thus, the two forms of mouse DNA polymerase alpha have partially, if not completely, different catalytic polypeptide structures, suggesting that the 7.3 S polymerase is not simply formed from DNA replicase by dissociation of the primase subunit.

Animals↗