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Results 801 - 850 of 857
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Weber B L - - 1990
C-myb, the normal cellular homolog of the retroviral transforming gene v-myb, encodes a nuclear, transcriptional regulatory protein (p75c-myb). C-myb is involved in regulating normal human hematopoiesis, and inhibits dimethyl sulfoxide-induced differentiation of Friend murine erythroleukemia (F-MEL) cells. An alternately spliced c-myb mRNA encodes a truncated version of p75c-myb (mbm2) that ...
Venturelli D - - 1990
We recently found that inhibition of MYB protein synthesis in human peripheral blood mononuclear cells (PBMC) exposed to human c-myb (designated MYB) antisense oligodeoxynucleotides prevents entry into S phase and cell proliferation. To determine the mechanism(s) by which down-regulation of human c-myb protein (MYB) synthesis interferes with DNA synthesis, we ...
Gewirtz A M - - 1990
Extracellular regulators of human megakaryocyte development are becoming better defined. How these regulators function at the subcellular and, in particular, the molecular levels remains almost completely unknown. The recent development of molecular micromethodologies such as in situ hybridization, the polymerase chain reaction, and the use of antisense oligodeoxynucleotides now make ...
Shen-Ong G L - - 1990
An alternative splicing event in which a portion of the intron bounded by the vE6 and vE7 exons with v-myb homology is included as an additional 363-nucleotide coding exon (termed E6A or coding exon 9A) has been described for normal and tumor murine cells that express myb. We show here ...
Madrid-Marina V - - 1990
We have studied the expression of mRNA encoding adenosine deaminase (ADA; EC 3.5.4.4), purine nucleoside phosphorylase (PNP; EC 2.4.2.1), and terminal deoxynucleotidyltransferase (TdT; EC 2.7.7.31) in different leukemic cell lines of B- and T-cell lineage. Incubation of leukemic cells in the presence of the phorbol esters, 12-O-tetradecanoyl-phorbol-13-acetate or phorbol 12,13-dibutyrate, ...
McClinton D - - 1990
During chemically induced differentiation of Friend virus-infected mouse erythroleukemia (MEL) cell lines, there is a biphasic down-regulation of the c-myb proto-oncogene. A plasmid containing a murine c-myb cDNA controlled by a mouse metallothionein I promoter was transfected into the C19 MEL cell line. For six transfected clones, it was found ...
Schirm S - - 1990
The oncogene v-myb of avian myeloblastosis virus is expressed from an mRNA that arises by splicing of the viral genome. In previous work, we described a mutant strain of avian myeloblastosis virus (tsAMV) that elicits temperature-sensitive transformation and suggested that the mutation affects production of the mRNA for v-myb. We ...
Nakamura T - - 1990
The present studies demonstrate that dimethylsulfoxide (DMSO) treatment of human U-937 myelomonocytic leukemia cells is associated with induction of monocytic differentiation. The DMSO-induced U-937 monocytic phenotype was associated with 1) growth inhibition, 2) loss of clonogenic survival, 3) increases in alpha-naphthyl acetate esterase (NSE) staining, and 4) increases in cell ...
Griffin M O - - 1990
In situ hybridization was used to study the effects of hemin on the expression of the oncogenes c-myc, c-fos, and myb, and on the mRNA level of erythroid porphobilinogen deaminase (PBG-D) and alpha-globin in HEL cells during differentiation. The technique was effective in detecting changes in mRNA levels in small ...
Valtieri M - - 1990
Highly purified erythroid burst-forming units (BFU-e) from human embryonic liver, adult marrow and blood were manipulated in vitro by cytokine addition in order to explore their requirements for c-myb function and potential for fetal hemoglobin (HbF) synthesis, particularly as related to their cycling activity. c-myb is expressed at a minimal ...
Tice-Baldwin K - - 1989
The BAS1 and BAS2 proteins are both required for activation of GCN4-independent (basal) HIS4 transcription in yeast. BAS1 has an NH2-terminal region similar to those of the myb proto-oncogene family. BAS1 and BAS2, which contains a homeo box, bound to adjacent sites on the HIS4 promoter. The joint requirement of ...
Vandenbunder B - - 1989
We have used in situ hybridization to study the spatial and temporal distribution of the transcription of three cellular oncogenes encoding DNA-binding proteins, c-ets 1, c-myb and c-myc during the development of the chick embryo. c-ets 1 mRNA expression appears linked to the mesodermal lineage and is strongly expressed in ...
Reddy C D - - 1989
The molecular mechanisms that modulate c-myb mRNA levels in hematopoietic cells appear to involve premature termination of transcription in the first intron of the gene. We have examined the DNA-protein interactions within the first intron of the c-myb gene and identified a 1.0-kilobase region that could be responsible for its ...
Nakagoshi H - - 1989
We report that the c-myb protein binds to another site, MBS-II, in the SV40 enhancer with low affinity. In co-transfection experiments with a c-myb expression plasmid, tandem repeats of the sequence containing the MBS-II site induced c-myb-dependent transcriptional repression. Results of mutational analyses of the sequence around the MBS-II site ...
Chinsky J M - - 1989
The mechanism by which the expression of adenosine deaminase (ADA, EC 3.5.4.4) is regulated in murine tissues was analyzed. Elevated levels of the specific activity of this enzyme appeared to correlate directly with steady state levels of ADA mRNA. Transcriptional studies using nuclear run-on experiments revealed a pronounced asymmetric distribution ...
Sakura H - - 1989
The c-myb protooncogene encodes a sequence-specific DNA-binding protein (c-Myb) that induces transcriptional activation or repression. We have identified three functional domains of the mouse c-Myb protein that are responsible for DNA binding, transcriptional activation, and negative regulation, respectively. In addition to the DNA-binding domain, which is located near the N ...
Churilla A M - - 1989
We previously reported that with time, after antigenic stimulation of antigen-regulated murine T lymphocyte clones, total IL-2-R expression decayed 10-50-fold, commensurate with a decline in the ability of the cells to proliferate to IL-2. However, late after antigenic stimulation, when the cells were refractory to the IL-2-proliferative stimulus, high levels ...
Chottiner E G - - 1989
A marked tissue-specific increase in erythrocyte adenosine deaminase (ADA) activity is associated with an autosomal dominantly inherited hemolytic anemia. We investigated the molecular basis of ADA overproduction by studying reticulocyte ADA mRNA from affected individuals. Analysis of proband reticulocyte ADA cDNA clones revealed normal sequence. RNase mapping demonstrated that the ...
Akeson A L - - 1989
Adenosine deaminase (ADA) deficiency in humans is one cause of severe combined immunodeficiency. When ADA fails to catalyze the deamination of adenosine and deoxyadenosine, the levels of deoxyadenosine that accumulate are toxic to lymphoid cells. Patients with complete ADA deficiency (e.g., with less than 5% normal ADA catalytic activity) lack ...
Prochownik E V - - 1989
Clonal lines of Friend murine erythroleukemia (F-MEL) cells have been generated following transfection with c-myc or c-myb expression plasmids. These clones produce high levels of abnormally regulated proto-oncogene transcripts and fail to terminally differentiate in the presence of dimethyl sulfoxide. To determine the relative levels at which the two proto-oncogenes ...
Richon V M - - 1989
The induction of murine erythroleukemia cells (MELC) to terminal differentiation by hexamethylene bisacetamide (HMBA) is accompanied by changes in the levels of c-myb and c-myc mRNA, and in p53 protein levels. We simultaneously examined the effects of HMBA on modulation of c-myb, c-myc and p53 mRNA and protein levels, and ...
Chottiner E G - - 1989
A kindred with an autosomal dominant form of chronic hemolytic anemia has been found to have a 40- to 70-fold elevation in erythrocyte adenosine deaminase (ADA) activity in association with depletion of red blood cell (RBC) ATP pools. ADA activities in B lymphoblasts, skin fibroblasts, and granulocytes were normal. There ...
Stallings R L - - 1989
The adenosine deaminase (ADA) locus appears to be under complex transcriptional control since levels of ADA enzyme activity vary greatly between different tissues and stages of development. Evidence that a trans-acting factor may be involved with the regulation of this locus came from previous experiments where fusion of ADA-negative human ...
McMahon J - - 1988
A minigene containing a cDNA encoding the normal mouse p80c-myb protein under strong promoter control was used to transfect Friend erythroleukaemia cells. Expression of the transfected gene was found to result in elevated levels of p80c-myb which were not subject to rapid down-modulation by inducers of Friend cell differentiation as ...
Todokoro K - - 1988
The role of nuclear protooncogenes during erythroid cell differentiation was examined by transfecting exogenous c-fos and c-myb genes into mouse erythroleukemia cells, which can be induced to differentiate either with erythropoietin (Epo) or dimethyl sulfoxide. Expression of exogenous c-myb or c-fos oncogene completely inhibited Epo-induced erythroid differentiation but only partially ...
Dautry F - - 1988
We have studied the mRNA accumulation of pim and myb genes in two interleukin 2- (IL2-)dependent, CTLL-2 and B6.1, and one IL3-dependent, FDC-P2, murine hematopoietic cell lines. To be able to dissociate the IL2 response from the phenomenon of lymphocyte activation, we used cell lines constitutively expressing the high affinity ...
Kharbanda S M - - 1988
The synthetic nucleoside analogue, tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide, NSC 286193) is an inhibitor of the enzyme inosine monophosphate (IMP) dehydrogenase and depletes guanine nucleotide pools. In the present study, we have monitored the effects of tiazofurin on human HL-60 promyelocytic cell differentiation and protooncogene expression. Tiazofurin (10 microM) induced a more differentiated ...
Klinken S P - - 1988
The proto-oncogenes myc, myb, and p53 produce nuclear proteins which have been implicated in the regulation of proliferation or differentiation in a number of systems. The expression of these proto-oncogenes was studied in murine erythroleukemia (MEL) cells during (i) normal replication, (ii) DMSO-induced differentiation and (iii), alpha-difluoromethylornithine (DFMO)-restricted cell division ...
Watson R J - - 1988
The mechanisms that modulate c-myb mRNA levels in mouse erythroleukemia cells induced toward erythroid differentiation were compared with those that act on c-myc. Both genes exhibited regulation at the levels of premature transcription arrest and RNA turnover. However, these common processes allowed temporally distinct control of gene expression.
Martinez-Valdez H - - 1988
Incubation of human thymocytes in the presence of phorbol esters caused a reversible decrease in the mRNAs encoding terminal deoxynucleotidyltransferase (TdT; EC 2.7.7.31) and adenosine deaminase (ADA; EC 3.5.4.4) and an increase in the mRNA encoding purine nucleoside phosphorylase (PNP; EC 2.4.2.1). The effect of phorbol esters on TdT and ...
Kim W K - - 1988
Sixteen proto-oncogenes which have generated retroviral oncogenes were tested for their expression in chicken leukemic cells induced by avian myeloblastosis virus (AMV) and five were found to be expressed (c-ets, c-fps, c-mht, c-myc, and c-rel). The size of the c-fps transcript (4.0 kb) was not in good agreement with the ...
Morisaki T - - 1988
We investigated the genetic basis for the increased adenosine deaminase (ADA) expression in adult T-cell leukemia (ATL). We found a correlation between the levels of ADA-specific mRNA and ADA immunoreactive protein in ATL. Southern blot analysis revealed no gene amplification or rearrangement of the ADA gene. These findings indicate that ...
Berkvens T M - - 1988
The housekeeping enzyme adenosine deaminase (ADA) shows a large variation in tissue-specific expression ranging from 1 Iu in red blood cells to 880 Iu in thymocytes. We investigated the acute lymphocytic leukemic cell line Molt-4 (660 Iu ADA/g protein) and the promyelocytic cell line HL-60 (38 Iu ADA/g protein) as ...
Thiele C J - - 1988
We detected expression of the c-myb proto-oncogene, which was initially thought to be expressed in a tissue-specific manner in cells of hematopoietic lineage, in human tissues of neuronal origin. Since the level of c-myb expression declined during fetal development, we studied the regulation of its expression in human neuroblastoma cell ...
Watson R J - - 1988
The control of c-myb mRNA abundance was examined in three representative cell lines, (the erythroleukaemia F4-12B2, the myeloma MOPC-31C and the fibroblast NIH3T3), which display abundant, low and undetectable levels of this transcript, respectively. We observed a small difference in half-life between F4-12B2 and MOPC-31C c-myb mRNA (175 min and ...
Clarke M F - - 1988
A full-length human c-myb cDNA clone has been isolated from a CCRF-CEM leukemia cell cDNA library. The plasmid vector contains simian virus 40-derived promotor, splice, and polyadenylation sequences as well as a transcription unit for a dihydrofolate reductase cDNA. We have introduced this construct into Friend erythroleukemia (F-MEL) cells and ...
Deguchi Y - - 1987
In the present study, we examined the various protooncogene expressions in PBMC (peripheral blood mononuclear cell) of systemic lupus erythematosus (SLE) patients to determine if they could be an indicator for the disease activity. We divided SLE patients into "very active," "active," and "remitting" states according to the clinical symptoms ...
Bender T P - - 1987
A series of murine B lymphoid tumor cell lines which are representative of the pre-B cell, immature and mature B cell, and plasma cell stages of B cell development have been examined for expression of c-myb proto-oncogene mRNA. The pre-B cell lymphoma cell lines express equivalent high steady state levels ...
Torelli G - - 1987
The expression of c-myb, c-myc, histone H3, and ornithine decarboxylase genes was examined by Northern blot analysis in the normal and neoplastic mucosa of ten subjects affected by colon cancer. The mRNA levels of c-myb protooncogene were detected at low levels in all normal samples but were increased in the ...
Bender T P - - 1987
Expression of c-myb proto-oncogene messenger RNA (mRNA) and protein has been detected principally in tumors and in normal tissue of hematopoietic origin. In each hematopoietic lineage examined, expression of the c-myb gene is markedly downregulated during hematopoietic maturation. However, the mechanism by which differential expression of the c-myb gene is ...
Watson R J - - 1987
Mouse c-myb gene transcripts in various cells of haemopoietic origin were analysed using S1 nuclease and RNase mapping techniques and by Northern blotting. It was found that the prevalent 3.8-kb c-myb mRNA present in thymocytes, T cell leukaemias, myelomonocytic leukaemias, erythroleukaemias and myeloid stem cells was initiated at several cap ...
Reed J C - - 1987
We have compared the effects of a mitogenic lectin, concanavalin A (Con A), and a growth factor, interleukin-2 (IL-2), on the expression of the c-myc, c-fos, and c-myb proto-oncogenes in cloned T lymphocytes. Accumulation of c-myc mRNA was induced by both ConA and IL-2 in these cells. In contrast, expression ...
Lee J - - 1987
Terminal differentiation of human monocytic leukemia cells (THP-1 cells) was associated with the induction of c-fos, the down regulation of c-myb, and no significant change in the level of c-myc expression. Gamma interferon, which resulted in a slight decrease in c-myb but no change in c-fos or c-myc expression, had ...
Basset N - - 1987
The abnormally high rate of proliferation described in cultured psoriatic fibroblasts could result from inappropriate expression of cellular oncogenes (c-onc) associated to the control of cell division. Four c-onc (c-Myc, c-Myb, c-Erb-B, c-H-Ras) were studied in cultured fibroblasts from lesional and nonlesional psoriatic skin (n = 6) and compared with ...
Ramsay R G - - 1986
Hexamethylenebisacetamide (HMBA)-induced differentiation of murine erythroleukemia cells (MELC) is a multistep process involving an early latent period during which a number of metabolic changes have been detected, but the cells are not yet committed irreversibly to differentiate. Commitment is defined as the capacity of MELC to go on to express ...
Nakabeppu Y - - 1986
Expression of the ada and alkA genes, both of which are involved in the adaptive response of Escherichia coli to alkylating agents, is positively controlled by Ada protein, the product of the ada gene. Large amounts of ada- and alkA-specific RNA were formed in cells treated with a methylating agent, ...
Emilia G - - 1986
The expression of three onc-genes, c-myc, c-myb and c-fes, has been evaluated at the cellular level in myeloid and erythroid precursors of normal human bone marrow, by "in situ" hybridization with tritium-labelled probes. A relatively large amount of m-RNA from the three onc-genes was detected in myeloblasts and promyelocytes, but ...
Turner C M - - 1986
The variable antigen repertoire expressed by metacyclic Trypanosoma brucei rhodesiense is not influenced by the anamnestic expression whereby the variable antigen type (VAT) ingested by a tsetse fly is present at high levels in early bloodstream populations of fly-infected mice. This has been demonstrated by feeding to Glossina morsitans a ...
Eisenman R N - - 1986
The protein products of the retroviral oncogenes, v-myc, v-myb and v-fos, and their normal cellular counterparts, the c-myc, c-myb and c-fos proto-oncogenes, have been found to be localized predominantly in the nucleus. In view of the oncogenicity of the retroviral forms of these genes, it is probable that they have ...
Torelli G - - 1985
The expression of c-myb in normal human T lymphocytes directly derived from a normal subject and not adapted to continuous growth in culture was found to be markedly increased after phytohemagglutinin stimulation. In the same cells, the expression of c-myc mRNA is a much earlier event compared with the appearance ...
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