Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chemically induced differentiation of Friend murine erythroleukemia cells (F-MELC) is a multistep process with a latent period of about 12 h preceding irreversible commitment to terminal maturation. To gain understanding of the early genetic response of F-MELC to the dimethyl sulfoxide (DMSO) inducer of F-MELC differentiation, we have investigated by Northern blot analysis the expression of fos and jun family genes that encode components of the transcription factor AP-1 complex. Our results show that c-jun mRNA is not detected at any time in untreated and DMSO-treated F-MELC. In contrast, DMSO-induced differentiation of F-MELC is associated with an early and transient induction of c-fos and junB mRNAs by 2 to 8 h treatment while in presence of dexamethasone, an inhibitor of F-MELC commitment, c-fos mRNA is not detected and junB mRNA remains at basal levels. junD mRNA is detected at low levels in untreated F-MELC and remains unchanged during DMSO treatment. Furthermore, DMSO treatment in a F-MELC cell line resistant to DMSO-differentiation does not result in an early induction of c-fos and junB mRNAs. Taken together, these results indicate that the DMSO-induced F-MELC differentiation is accompanied by an early co-induction of c-fos and junB during the latent period preceding the commitment to erythroid maturation.
Leukemia 1992 Sep
PMID:Co-induction of c-fos and junB during the latent period preceding commitment of Friend erythroleukemia cells to differentiation. 151 4

Human T-cell leukemia virus type 1 (HTLV-1) is an etiological agent of adult T-cell leukemia (ATL). We showed here by mobility-shift assay that T-cell lines transformed with the virus contained high levels of AP-1 activities. Consistent with this result, these cell lines expressed increased levels of mRNAs encoding the AP-1 proteins, c-Fos, Fra-1, c-Jun, JunB, and JunD. Previously, transcription of the c-fos gene has been reported to be transactivated by the viral transcription factor, Tax1. By using the human T-cell line (JPX-9), in which expression of the Tax1 is inducible, we showed that expression of mRNAs for Fra-1, c-Jun, and JunD was also transactivated by Tax1. Moreover, Tax1 activated expression of two other transcription factors having zinc finger motifs, Egr-1 and Egr-2, in the same cells. The Tax1-inducible transcription factors identified here are encoded by the members of immediate early genes under the control of growth signals. Thus, Tax1 was suggested to replace growth signals, at least in part, by this mechanism.
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PMID:HTLV-1 Tax induces expression of various immediate early serum responsive genes. 190 55

Human T-cell leukemia virus type I (HTLV-I) encodes a 40-kDa nuclear protein, Tax, which stimulates transcription from three 21-base pair (bp) repeats in its U3 region. Tax trans-activation is mediated via cellular factors that interact with the TGACGT motifs in the 21-bp repeats. Gel mobility shift assay and UV cross-linking analysis show that two proteins of 52 and 46 kDa in size bind the 21-bp repeat specifically. Base substitutions in the TGACGT motif which abolished Tax trans-activation abrogated factor binding whereas the repeats containing mutations that did not affect Tax trans-activation supported factor binding as the wild-type repeat. The 52- and 46-kDa factors are present in human T-cell lines Jurkat and MT4 (HTLV-I transformed) and in HeLa cells but are undetectable in a human placental cell line JEG-3, which gave a reduced level of trans-activation. JEG-3 extracts contain a distinct DNA binding activity that shows analogous sequence requirements as the 52- and 46-kDa proteins in interacting with the various 21-bp repeats. c-Jun and CREB (cAMP-responsive element binding factor) can stimulate transcription from HTLV-I long terminal repeats in JEG-3 cells. At least two copies of the 21-bp repeats are required for optimal trans-activation by c-Jun and CREB. Most single point mutations in the TGACGT motif that abolished Tax trans-activation, however, did not affect c-Jun- or CREB-directed transcriptional enhancement. These data indicate that many transcription factors including c-Jun and CREB exert stimulatory effects on HTLV-I transcription although they do not directly respond to Tax. The 52- and 46-kDa cellular proteins most likely are involved directly in Tax-mediated trans-activation, and they are tentatively named Tax activation factors I and II, respectively.
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PMID:Cellular factors involved in transcription and Tax-mediated trans-activation directed by the TGACGT motifs in human T-cell leukemia virus type I promoter. 224 93

Ceramide has emerged as a novel lipid mediator in cell proliferation, differentiation, and apoptosis. In this work, we demonstrate that the levels of c-jun mRNA, c-Jun protein, and DNA binding activity of a nuclear transcription factor AP-1 to 12-o-tetradecanoylphorbol 13-acetate responsive elements all increased following treatment with the cell-permeable ceramide, N-acetylsphingosine in human leukemia HL-60 cells. N-Acetylsphingosine (1-10 microM) increased the levels of c-jun mRNA in a dose-dependent manner, and maximal expression was achieved 1 h after treatment. Increase of c-jun expression treated with 5 microM N-acetyldihydrosphingosine, which could not induce apoptosis, was one third of that with 5 microM N-acetylsphingosine. Ceramide-induced growth inhibition and DNA fragmentation were both prevented by treatment with curcumin, 1,7-bis[4-hydroxy-3-methoxy-phenyl]-1,6-heptadiene-3,5-dione (an inhibitor of AP-1 activation), or antisense oligonucleotides for c-jun. These results suggest that the transcription factor AP-1 is critical for apoptosis in HL-60 cells and that an intracellular sphingolipid mediator, ceramide, modulates a signal transduction inducing apoptosis through AP-1 activation.
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PMID:Requirement of AP-1 for ceramide-induced apoptosis in human leukemia HL-60 cells. 759 95

Moloney murine leukemia virus (Mo-MuLV) is a thymotropic and leukemogenic retrovirus which causes T lymphomas. The long terminal repeat (LTR) of Mo-MuLV affects the regulation of a number of cellular genes, including collagenase IV, monocyte chemoattractant protein-1, and c-jun genes, all of which contain 12-O-tetradecanoylphorbol-13-acetate-responsive element consensus sites within their promoters. We report here that Mo-MuLV stimulates the collagenase IV gene through transcription factor AP-1, and that the expression of a subgenomic portion of Mo-MuLV LTR alone is sufficient for this effect. Transient or stable expression of the viral LTR increases cellular AP-1 DNA binding activity. The collagenase IV 12-O-tetradecanoylphorbol-13-acetate-responsive element consensus sequence was shown to be required for this trans-activation. Deletions or mutations of this consensus site which abolished AP-1 binding also abolished trans-activation by the LTR. Transient or stable transfection of the viral LTR into cells stimulated c-jun gene expression, suggesting one mechanism whereby the viral LTR may induce cellular AP-1 activity. Thus, the Mo-MuLV LTR, through activation of the transcription factor AP-1, is capable of regulating cellular gene expression, including the induction of proto-oncogenes. This activity may be relevant to the mechanisms whereby retroviruses which do not contain oncogenes induce neoplasia.
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PMID:The Moloney leukemia retroviral long terminal repeat trans-activates AP-1-inducible genes and AP-1 transcription factor binding. 777 15

Human proenkephalin gene transcription is transactivated by human T-cell leukemia virus type I (HTLV-I) Tax in human Jurkat T lymphocytes. This transactivation was further enhanced in Jurkat cells treated with concanavalin A, cyclic AMP, or 12-O-tetradecanoylphorbol-13-acetate. Deletion and cis-element transfer analyses of the human proenkephalin promoter identified a cyclic AMP-responsive AP-1 element (-92 to -86) as both necessary and sufficient to confer Tax-dependent transactivation. Different AP-1 or cyclic AMP-responsive element-binding protein (CREB)/activating transcription factor (ATF) proteins which bind this element were expressed in murine teratocarcinoma F9 cells to identify those capable of mediating Tax-dependent transactivation of human proenkephalin gene transcription. Although CREB, c-Fos, c-Jun, and JunD did not have significant effects, JunB inhibited the Tax-dependent transactivation. In contrast, ATF3 dramatically induced Tax-dependent transactivation, which was further enhanced by protein kinase A. Electrophoretic mobility shift assays with recombinant fusion proteins expressed and purified from bacteria indicate that the DNA-binding activity of ATF3 is also dramatically enhanced by Tax. Chimeric fusion proteins consisting of the DNA-binding domain of the yeast transcription factor Gal4 and the amino-terminal domain (residues 1 to 66) of ATF3 were able to mediate Tax-dependent transactivation of a Gal4-responsive promoter, which suggests a direct involvement of this region of ATF3. Recombinant fusion proteins of glutathione S-transferase with either the amino- or carboxy-terminal (residues 139 to 181) domain of ATF3 were able to specifically interact with Tax. Furthermore, specific antisera directed against Tax coimmunoprecipitated ATF3 only in the presence of Tax.
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PMID:Novel interactions between human T-cell leukemia virus type I Tax and activating transcription factor 3 at a cyclic AMP-responsive element. 800 91

The Jun protein binds DNA and regulates transcription as a component of the AP-1 transcription factor complex. In its oncogenic form, Jun can transform cells in culture and cause tumors in animals. Both trans-activation and transformation require several functional domains of Jun, including an amino-terminal trans-activation domain. In this study, properties of Jun required for trans-activation and transformation were explored by replacing the trans-activation domains of c-Jun and its oncogenic counterpart, v-Jun, with the constitutively active trans-activation domain from the herpes simplex virus VP16 protein. The VP16-v-Jun chimera retained similar oncogenic properties to its parent, v-Jun. The VP16-c-Jun chimera, however, was considerably more oncogenic than c-Jun. Substitutions of a phenylalanine in the VP16 domain of the VP16-c-Jun chimera diminished or abolished transformation. Each of the chimeras bound to the AP-1 consensus recognition sequence from the collagenase promoter or from the human T-cell leukemia virus type I long terminal repeat in vitro. None of the VP16-Jun chimeras efficiently stimulated transcription from the collagenase promoter or an artificial promoter containing the human T-cell leukemia virus type I element in vivo. These results demonstrate that the Jun trans-activation domain can be replaced by a heterologous trans-activation domain with retention of oncogenic activity. However, this oncogenic activity is not reflected in the trans-activating properties of the chimeras.
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PMID:Chimeras of herpes simplex viral VP16 and jun are oncogenic. 824 Oct 24

Skeletal myoblasts undergo terminal differentiation when maintained under low-mitogen conditions. We have examined the expression of c-jun, one of the growth-factor-inducible immediate-early genes, during myogenic differentiation of L6 myoblasts. The steady-state levels of c-jun mRNA, c-Jun polypeptide, and activator protein 1 binding activity were not markedly altered in L6 cells undergoing myogenic differentiation. Although expression of c-jun is induced by serum mitogens in fibroblasts and other cell lines, addition of high serum to proliferating myoblasts resulted in the activation of another immediate early gene junB, but not c-jun mRNA expression. These results indicate that regulation of c-jun may differ from that of other immediate early genes in L6 cells. Manipulation of myogenesis by exposing L6 cells to dimethyl sulfoxide also suggested that expression of myogenin and muscle differentiation could occur in the presence of high levels of c-Jun. Furthermore, expression of c-jun from Moloney murine leukaemia viral long-terminal repeat in transfected L6 cells confirmed that constitutive expression of c-jun does not interfere with myogenesis in L6 myoblasts. Therefore, regulation of c-jun expression in rat L6 cells differs from that in the mouse C2 cell line.
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PMID:Expression of the protooncogene c-jun is maintained during myogenic differentiation in rat L6 myoblasts. 827 67

The leukemogenic tyrosine kinase fusion protein Bcr-Abl activates a Ras-dependent pathway required for transformation. To examine subsequent signal transduction events we measured the effect of Bcr-Abl on two mitogen-activated protein kinase (MAPK) cascades--the extracellular signal-regulated kinase (ERK) pathway and the Jun N-terminal kinase (JNK) pathway. We find that Bcr-Abl primarily activates JNK in fibroblasts and hematopoietic cells. Bcr-Abl enhances JNK function as measured by transcription from Jun responsive promoters and requires Ras, MEK kinase (MAPK/ERK kinase kinase), and JNK to do so. Dominant-negative mutants of c-Jun, which inhibit the endpoint of the JNK pathway, impair Bcr-Abl transforming activity. These findings implicate the JNK pathway in transformation by a human leukemia oncogene.
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PMID:The Bcr-Abl leukemia oncogene activates Jun kinase and requires Jun for transformation. 852 41

A novel cellular gene, SFA-2, was isolated by differential hybridization of a cDNA library, using probes obtained from an adult T-cell leukemia cell line in comparison with normal CD4+ T cells and MOLT-4 cell line. The mRNA of the SFA-2 gene is approximately 0.9-kb in size and encodes a protein of 125 amino acids, containing a basic region-leucine zipper DNA-binding domain. The N-terminal region of SFA-2 is rich in serine and contains a consensus sequence for casein kinase II phosphorylation. The SFA-2 gene was strongly expressed in mature T and B lymphocytes, and was up-regulated after transformation by human T-cell leukemia virus type I. The SFA-2 did not homodimerize efficiently but formed heterodimer preferentially with c-Jun. The SFA-2/c-Jun heterodimer bound preferentially to the AP-1 and CRE sites.
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PMID:SFA-2, a novel bZIP transcription factor induced by human T-cell leukemia virus type I, is highly expressed in mature lymphocytes. 863 63


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