Biomedical subjects

Y Tsujimoto

Publications and source records attributed to Y Tsujimoto.

At least 163 records · Page 9Linked to original sources

PubMed1992

Differential effects of Bcl-2 on T and B cells in transgenic mice.

We have produced bcl-2 transgenic mice by using a construct which mimics the t(14;18) translocation in human follicular lymphomas. Although lymphoid tissues from all transgenic mice contained high levels of human Bcl-2 protein, transgene expression was differentially regulated within the B- and T-cell compartments of lines derived from various founder mice. We have characterized the phenotypes of two lines of bcl-2 transgenic mice (line 2 and line 6) in which bcl-2 transgene expression was restricted primarily to the T- or B-cell lineages, respectively. Analysis of line 6 lymphocytes revealed a polyclonal expansion of B cells, and these B cells exhibited prolonged survival in vitro. In line 2 mice, numbers of T cells in the peripheral lymphoid tissues were more moderately elevated despite enhanced T-cell survival in vitro. Line 2 transgenic mice also showed significantly increased proportions of thymocytes with a mature phenotype. Taken together, these findings suggest different roles for bcl-2 in the in vivo regulation of B- and T-cell development and homeostasis.

Animals↗

PubMed1992

Prevention of programmed cell death of sympathetic neurons by the bcl-2 proto-oncogene.

Approximately half of the neurons produced during embryogenesis normally die before adulthood. Although target-derived neurotrophic factors are known to be major determinants of programmed cell death--apoptosis--the molecular mechanisms by which trophic factors interfere with cell death regulation are largely unknown. Overexpression of the bcl-2 proto-oncogene in cultured sympathetic neurons has now been shown to prevent apoptosis normally induced by deprivation of nerve growth factor. This finding, together with the previous demonstration of bcl-2 expression in the nervous system, suggests that the Bcl-2 protein may be a major mediator of the effects of neurotrophic factors on neuronal survival.

Animals↗

PubMed1992

Isolation and characterization of the chicken bcl-2 gene: expression in a variety of tissues including lymphoid and neuronal organs in adult and embryo.

The expression of human bcl-2 gene is de-regulated by t(14;18) translocation in most of follicular lymphoma. Recent studies indicated that the bcl-2 gene product has an ability to block apoptosis of hematopoietic cells. To facilitate the analysis of the role of this gene in normal development using an animal model, we have isolated and partially characterized the chicken homologue of human bcl-2 gene. The analysis of nucleotide sequence showed that the organization of the chicken bcl-2 gene is very similar to that of human bcl-2 gene. The primary transcript is spliced to encode a 25,687 dalton (233 a.a.) protein. The chicken Bcl-2 protein has two regions highly homologous to human Bcl-2 protein surrounding a totally non-homologous region. The expression of the chicken bcl-2 gene was analyzed in various chicken tissues. In the adult chicken, bcl-2 transcripts were detected in thymus, spleen, kidney, heart, ovary and brain, with the highest levels being detected in the thymus. However, the bursa of Fabricius, which is the site of early B cell development, expressed much less amounts of bcl-2 RNA. On the other hand, in embryo, the gene is extensively expressed in the bursa, as well as in muscle and the above tissues. Our findings indicate that a homologue of the human bcl-2 gene does exist in the chicken and that its expression is developmentally regulated in some tissues.

Amino Acid Sequence↗

PubMed1992

Correlation of CD2 expression with PML gene breakpoints in patients with acute promyelocytic leukemia.

The chromosomal translocation t(15;17)(q22:21) of acute promyelocytic leukemia (APL) fuses PML, a novel gene, with RAR alpha, a retinoic acid receptor gene. PML-RAR hybrid transcripts were studied in 18 cases of APL using RNA-PCR. Two forms were noted: one designated 5', producing a 439-bp chimeric fragment, and a 3' form, producing a pair of fragments of 765 bp and 909 bp. 5' forms were found in 7 of the 18 cases while the other 11 patients expressed the 3' forms. The chromosome 15 specific probes K3 and K2 were used to study genomic breakpoints in 12 APL patients. Comparison of these results with RNA PCR in 11 patients for whom both were available yielded a rearrangement pattern predictive of whether the hybrid transcript was 5' or 3'. In this way, an additional three patients in whom DNA but not RNA was available were identified as having 3' (downstream) breakpoints and, therefore, 3' hybrid forms. Thus, 21 cases categorized as having 5' or 3' PML-RAR transcripts were analyzed for various phenotypic differences. Surface phenotyping of leukemic promyelocytes demonstrated expression of the CD2 antigen in all cases with the 5' splice variant. Only 1 of 11 cases with the 3' form showed CD2 expression. This difference is significant at P = .001.

Adult↗

PubMed1992

Expression of the bcl-2 gene in human multiple myeloma cell lines and normal plasma cells.

The bcl-2 gene, encoding a mitochondrial membrane protein suggested to play an important role in cell survival, is translocated into the Ig loci in about 80% of human follicular lymphomas, which results in a high level of expression. This report shows that bcl-2 was expressed in eight of eight human multiple myeloma cell lines and in normal lymph node and bone marrow plasma cells. In the majority of the myeloma lines, the level of expression was comparable with that observed in Karpas 422, a follicular lymphoma cell line carrying a 14;18 translocation of the bcl-2 gene. DNA rearrangements of the bcl-2 locus were evident in only one of the myeloma cell lines, U-266-1970. In this cell line, which exhibited the highest bcl-2 expression, a fourfold increased copy number of the bcl-2 gene was estimated by Southern analysis. This amplification was lost in cells of later passages (U-266-1984), suggesting that bcl-2 might possibly have played a role in the tumor development in vivo. Our results are in contrast to previous observations in murine plasmacytoma, in which bcl-2 was shown to be silent. The results also contradict the published observation that bcl-2 is not expressed at terminal stages of B-cell differentiation. It is at present unclear whether the high expression of bcl-2 in human myeloma is the result of a deregulated expression associated with the malignant phenotype or a mere reflection of the bcl-2 expression typical of normal plasma cells.

Blotting, Southern↗

PubMed1992

Localization of 11q13 loci with respect to regional chromosomal breakpoints.

We have employed two strategies to map 13 markers located at 11q13. First, we used pulsed-field gel electrophoresis of DNA fragments obtained with methylation-sensitive restriction enzymes. The markers used in this study were scattered over 8.4 Mb and, for most of them, could not be linked one to another. A second mapping strategy employed hybridization to either DNA of somatic hybrids containing various parts of the long arm of chromosome 11 or metaphase chromosomes of a B-cell line containing the t(11;14)(q13;q32) translocation. We were able to sort out the centromeric from the telomeric probes with respect to translocation breakpoints taken as reference chromosomal landmarks by this approach. BCL1, which corresponds to the region where the t(11;14)(q13;q32) translocation breakpoints are clustered, appears as a boundary between two areas of human/mouse homology present in conserved syntenic regions on mouse chromosomes 7 and 19.

Animals↗

PubMed1992

[Morphological and physiological change in the dis-used bladder of hemodialysis patients].

We studied 48 patients who underwent renal transplantation during the period of July, 1983 and May, 1988 and were free of episodes of neurogenic bladder in the past history. The average age was 27.6 +/- 9.5 years old, and mean 24 hour urine output was 249 +/- 396 ml. Cystometry was performed preoperatively in 39 patients. The average bladder capacity decreased to 112 +/- 69 ml (n = 39) and only 29.0% of the patients exhibited normal compliance (> 50 ml/cmH2O) (n = 35). Biopsy of the bladder wall was performed in 22 patients during the operation. The purpose of this study is to ascertain what physiological and pathological change may occur in the disused human bladder with low capacity and low compliance. Response of muscle tissue to carbachol were examined in 7 specimens and that of isoproterenol were examined in 9 patients. The minimum concentration of carbachol at which muscle contraction was exhibited did not differ from that of the control group. The minimum concentration of isoproterenol at which autonomous muscle activity was completely inhibited increased in cases with decreased 24 hour urine output. ED50 value of inhibition by isoproterenol to the muscle contraction during field stimulation exhibited that the inhibitory action of isoproterenol on muscle contraction declined in the cases with decreased 24 hour urine output. Pathological change of the smooth muscle layer were observed in 17 patients. Muscle cell atrophy was recognized in 29.4% of the patients and vacuolar change of smooth muscle cells was seen in 64.7%. Muscle bundle atrophy was observed in 23.5% and fibrosis was seen in 52.9%.

Adolescent↗

PubMed1992

Bcl-2 confers growth and survival advantage to interleukin 7-dependent early pre-B cells which become factor independent by a multistep process in culture.

Early pre-B cells derived from mouse lymphoid bone marrow cultures were expanded on a surrogate stromal cell line composed of NIH3T3 fibroblasts engineered to secrete interleukin 7 (IL-7). Three immortal, IL-7-dependent cell lines were generated and infected with recombinant retroviruses to determine the effects of the human follicular B-cell lymphoma gene, bcl-2, on immature stages of B-cell development. Cells expressing bcl-2 grew at rates similar to those of control (vector only) cells when plated on bone marrow stromal lines, but exhibited a c. two-fold net proliferative advantage when grown in liquid medium supplemented with IL-7 alone. Bcl-2 prevented apoptosis when the infected early pre-B-cell lines were deprived of IL-7 and other growth factors provided by stromal cells. Following factor deprivation, a subset of cells expressing bcl-2 survived indefinitely. Two such cultures spontaneously gave rise to factor-independent variants which grew slowly in unsupplemented liquid culture and formed agar colonies, yet still responded positively to IL-7 and kit ligand, and negatively to gamma-interferon. Bcl-2 thus provides a survival capacity and modest growth advantage to early pre-B cells, which may recapitulate its effects in human B cells bearing t(14;18) translocations and ultimately contribute to transformation.

Animals↗

PubMed1992

Cytogenetic 2; 18 and 18; 22 translocation in chronic lymphocytic leukemia with juxtaposition of bcl-2 and immunoglobulin light chain genes.

The majority of follicular lymphoma cells carry the typical chromosome translocation 14;18, which juxtaposes the bcl-2 gene to the immunoglobulin heavy-chain (IgH) gene. Variant translocations of the bcl-2 gene to the Ig lambda or Ig kappa gene have been found by molecular biological techniques in a significant fraction (approximately 10%) of chronic lymphocytic leukemia (CLL). However, there have been no reports describing the presence of cytogenetic 18;22 and 2;18 translocations in CLL, in spite of extensive karyotypic studies. We present here two cases of CLL, one with cytogenetically detected t(2;18)(p11;q21) and the other with the t(18;22)(q21;q11). The molecular analysis revealed that these translocations juxtaposed the bcl-2 and immunoglobulin light-chain (IgL) genes. The t(18;22) broke the 5' flanking region of the bcl-2 gene and juxtaposed to the immunoglobulin lambda light-chain (Ig lambda) gene in a head-to-head configuration, as in the cases previously described. In the case of the t(2;18), the bcl-2 gene and immunoglobulin kappa light-chain (Ig kappa) gene were juxtaposed in a head-to-tail configuration, which is opposite to that expected from the orientation of the genes on chromosomes. The breakpoint was located within the 5' untranslated region of the bcl-2 gene. The results presented here indicate that the bcl-2/immunoglobulin light-chain (IgL) gene juxtaposition seen in a fraction of CLL is the result of cytogenetically detectable reciprocal chromosome translocations 2;18 and 18;22.

Base Sequence↗

PubMed1991

PRAD1, a candidate BCL1 oncogene: mapping and expression in centrocytic lymphoma.

Rearrangement of the BCL1 (B-cell lymphoma 1) region on chromosome 11q13 appears to be highly characteristic of centrocytic lymphoma and also is found infrequently in other B-cell neoplasms. Rearrangement is thought to deregulate a nearby protooncogene, but transcribed sequences in the immediate vicinity of BCL1 breakpoints had not been identified. PRAD1, previously designated D11S287E, was identified on 11q13 as a chromosomal breakpoint region rearranged with the parathyroid hormone gene in a subset of parathyroid adenomas; this highly conserved putative oncogene, which encodes a novel cyclin, has been linked to BCL1 and implicated also in subsets of breast and squamous cell neoplasms with 11q13 amplification. We report pulsed-field gel electrophoresis data showing BCL1 and PRAD1 to be no more than 130 kilobases apart. PRAD1 mRNA is abundantly expressed in seven of seven centrocytic lymphomas (Kiel classification), in contrast to 13 closely related but noncentrocytic lymphomas. Three of the seven centrocytic lymphomas had detectable BCL1 DNA rearrangement. Also, two unusual cases of CLL with BCL1 rearrangement overexpressed PRAD1, in contrast to five CLL controls. Thus, PRAD1 is an excellent candidate "BCL1 oncogene." Its overexpression may be a key consequence of rearrangement of the BCL1 vicinity in B-cell neoplasms and a unifying pathogenetic feature in centrocytic lymphoma.

Chromosomes, Human, Pair 11↗

PubMed1991

Molecular cloning of the chromosomal breakpoint of a B-cell lymphoma with the t(11;14)(q23;q32) translocation.

The breakpoint of t(11;14)(q23;q32) chromosome translocation in a B-cell lymphoma line, RC-K8, was cloned. Immunoglobulin heavy chain (IGH) constant gene, C gamma 2 at the 5' end, was involved in this translocation, and the DNA segment juxtaposed to the C gamma 2 was proved to be derived from chromosome 11 by somatic cell hybrid study. The normal counterpart of chromosome 11 was also isolated. With a DNA probe near the breakpoint of chromosome 11, Southern blot analysis of RC-K8 and 10 other cases with translocation involving the 11q23 region was conducted, but no rearrangement bands have been observed thus far except for RC-K8.

Base Sequence↗

PubMed1991

Effect of platelet-activating factor on cortisol and corticosterone secretion by perfused dog adrenal.

Administration of platelet-activating factor (PAF) to perfused adrenal increased cortisol and corticosterone secretion. With hexadecyl PAF (C16PAF; 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine), the increase was significant at 1 nM and maximal at 10 nM. The responses to 10 nM octadecyl PAF (C18PAF; 1-O-octadecyl-2-acetyl-sn-glycero-3-phosphocholine) were one fourth of those to 10 nM C16PAF. The addition of C16PAF to dispersed adrenal cells significantly increased cortisol and corticosterone production at 0.1 nM and 10 nM, respectively. C16PAF was about 1000 times more potent than histamine on a molar basis in respect to cortisol response in both perfused adrenal and dispersed adrenal cells. The results suggest that PAF induces cortisol release from dog adrenal.

Adrenal Cortex↗

PubMed1991

D11S146 and BCL1 are physically linked but can be discriminated by their amplification status in human breast cancer.

Band q13 of chromosome 11 is frequently altered in a number of human cancers. We have undertaken physical mapping in this region, starting with D11S146, an anonymous 11q13 DNA fragment. This probe has been used by others as a landmark to locate MEN1, a locus of predisposition to multiple endocrine neoplasia. Long-range restriction mapping locates D11S146 within approximately 400 kb of the BCL1 translocation breakpoint involved in certain B-cell malignancies. BCL1 and two proto-oncogenes, INT2 and HST, were previously found to be coamplified in approximately 1/5 breast carcinomas. Although close to BCL1, D11S146 is present in less than 3/4 of these amplification units and delimits their centromeric boundary. Therefore, we propose that D11S146 defines two genetic regions. The centromeric region--PYGM/D11S146--contains MEN1. The telomeric one includes the D11S146/BCL1/INT2/HST area and is relevant to DNA amplification in carcinomas and to B-cell translocations.

Breast Neoplasms↗

PubMed1991

Further study on selective transmission of mitochondrial DNA in heteroplasmic lines of Drosophila melanogaster.

The temperature-dependent transmission of mitochondrial DNA (mtDNA) was investigated in heteroplasmic lines of Drosophila melanogaster established by germ-plasm transplantation. Using D. melanogaster, D. simulans and D. mauritiana as germ-plasm donors, five recipient-donor combinations of heteroplasmy, differing from those previously examined (Matsuura et al., 1991), were constructed. For intraspecific reciprocal combinations, donor mtDNA in one combination was retained at 25 degrees C but was almost lost by the tenth generation at 19 degrees C. In the reciprocal, the proportion of the same type of recipient mtDNA decreased more quickly at 19 degrees C than 25 degrees C. Decreasing rates at 19 degrees C in the reciprocals differed from each other. For interspecific combinations, two species were used as germ-plasm donors. Donor mtDNA derived from D. simulans was lost at both temperatures and the rate of decrease was greater at 19 degrees C than 25 degrees C. The proportion of donor mtDNA derived from D. mauritiana increased at a greater rate at 25 degrees C than 19 degrees C when using two different strains of D. melanogaster as recipients. These results suggest that both the nuclear and two types of mitochondrial genomes are involved in the selective transmission of mtDNA.

Animals↗

PubMed1991

Modulation of LFA-1 surface antigen expression by activated H-ras oncogene in EBV-infected human B-lymphoblast cells.

The lymphocyte-associated antigen 1 (LFA-1) involved in a wide range of cellular adhesion-dependent immunological functions, including interaction of cytotoxic T lymphocytes with their target, is implicated in tumorigenesis. The modulation of the LFA-1 antigen expression was studied in Epstein-Barr virus (EBV)-immortalized human B-lymphoblastoid cell lines, transfected with human oncogenes, H-ras and c-myc. We observed by flow cytometry that the activated H-ras (EJ) gene, but not its normal counterpart, consistently enhanced LFA-1 expression. The RNA analysis revealed that induction of the LFA-1 surface antigen by the EJ gene occurred through the level of the alpha-chain but not the beta-chain mRNA of LFA-1. The LFA-1 molecules induced by the EJ gene were functional; cells with the EJ gene revealed an elevated level of homocytic cellular adhesion, which was blocked by the anti-LFA-1 monoclonal antibody. Flow cytometry analysis indicated that the modulation of the LFA-1 antigen expression was a phenomenon specific to the EJ gene. The high levels of expression of c-myc and blc-2 gene did not affect LFA-1 antigen expression. The system used here provides a tool by which the signal transduction pathway involving the H-ras gene and the molecular mechanism of LFA-1 gene expression can be genetically dissected.

B-Lymphocytes↗

PubMed1991

Germ line configuration of the BCL-2 major breakpoint region in hyperplastic lymph nodes.

The configuration of the BCL-2 major breakpoint region was analyzed by Southern blot hybridization and polymerase chain reaction amplification in DNA derived from 44 benign hyperplastic lymph nodes with follicular overgrowth. None of the cases exhibited translocation of the BCL-2 gene at the major breakpoint region of chromosome 18. The potential usefulness of molecular genetic detection of BCL-2 translocation in the differential diagnosis between hyperplastic lymph nodes and lymphomas is suggested.

Base Sequence↗

PubMed1991

[B-CLL and bcl-2 gene].

Most of human follicular lymphomas (approximately 90% in U.S.A. or approximately 30% in Japan) possess the t(14; 18) chromosome translocation that directly involves the IgH locus on chromosome 14 and the bcl-2 gene on chromosome 18. The t(14; 18) chromosome translocation occurs nearly exclusively at two hot spots, a major breakpoint clustering region (mbr) within the 2nd exon noncoding region and the minor breakpoint clustering region (mcr) within the 3' flanking region of the bcl-2 gene. Here we show that the rearrangement of the bcl-2 gene occurs in a significant fraction (approximately 10%) of B-CLL. All of the rearranged bcl-2 genes were juxtaposed with Ig lambda or Ig kappa genes, implying that the bcl-2 gene is preferentially linked to the IgL genes in CLL.

Base Sequence↗

PubMed1990

Molecular characterization of a t(11;14)(q23;q32) chromosome translocation in a B-cell lymphoma.

We have analyzed the molecular features of a t(11;14)(q23;q32) chromosome translocation of a cell line established from a B-cell lymphoma. Somatic hybrid cells carrying the 11q- and/or 14q+ chromosome(s) were produced in order to map the breakpoints. Southern blot analyses of DNAs from these hybrid cell lines together with various probes from the IGH locus on chromosome 14 and the ETS-1 and CD3 genes on chromosome 11 showed that the breakpoints of the translocation occurred between the constant regions of the C phi gamma and C gamma 2 genes on chromosome 14 and between the CD3 and ETS-1 genes on chromosome 11. The t(11;14)(q23;q32) translocation does not seem to involve the same mechanism that is responsible for translocations occurring at the immunoglobulin heavy chain joining segment (JH).

Antigens, CD↗