Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human IL-3 gene, located on chromosome 5, contains several cis-acting DNA sequences, i.e. CLE (conserved lymphokine element) and a GC-rich region, similar to the GM-CSF gene. To investigate the role of these elements, the 5' flanking region of the IL-3 gene was attached to a bacterial chloramphenicol acetyltransferase (CAT) gene. The fusion plasmids were analyzed by an in vitro transcription system using Jurkat cell nuclear extract prepared from cells stimulated with phorbol-12-myristate-13-acetate and calcium ionophore (PMA/A23187), introduced into Jurkat cells, expressed transiently, and stimulated by co-transfection of human T cell leukemia virus type I (HTLV-I) encoded transactivator, p40tax. The GC-rich region enhanced TATA-dependent transcription in the in vitro transcription system and also strongly responded to p40tax stimulation in the in vivo cotransfection assay. Using this GC-rich region as a probe, we identified a constitutive DNA-protein complex, alpha, whose binding specificity correlates with transcription activity. However, this element is not sufficient for the expression of the IL-3 gene in response to T cell activation signals (PMA/A23187) and no sequence was found within the IL-3 gene which mediates the response to PMA/A23187. The enhancer sequence which responds to T cell activation signals may be located outside the IL-3 gene and may be shared by other lymphokines, possibly by GM-CSF. We propose that the GM-CSF enhancer (CLE2/GC box) which mediates the response to T cell activation signals may stimulate the expression of the IL-3 gene.
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PMID:Definition of a GC-rich motif as regulatory sequence of the human IL-3 gene: coordinate regulation of the IL-3 gene by CLE2/GC box of the GM-CSF gene in T cell activation. 204 40

Four lines of transgenic mice containing the HIV LTR linked to the bacterial gene encoding chloramphenicol acetyltransferase (CAT) were constructed. In each line, a characteristic tissue pattern of CAT expression was observed with detectable levels present in the eye, heart, spleen, thymus, and tail. Low levels of CAT were present in circulating lymphocytes, but CAT activity in these cells could be augmented following treatment with the mitogen phytohemagglutinin (PHA). Likewise, CAT expression was present at only low levels in circulating monocytes, but higher levels of CAT were observed in macrophages grown in the presence of various cytokines (CSF-1, GM-CSF, IL-1 alpha, IL-4, and IL-2). Furthermore, Langerhans cells recovered from skin showed higher levels of CAT activity than those observed in other cells of monocyte-macrophage lineage. These results indicate that LTR-CAT expression in cells of monocyte-macrophage lineage may increase in proportion to the degree of differentiation of these cells. These animals may be useful in the study of cell-specific determinants of LTR-directed gene activity and may serve to identify exogenous cofactors that promote the progression of HIV-related disease in vivo.
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PMID:The human immunodeficiency virus long terminal repeat is preferentially expressed in Langerhans cells in transgenic mice. 254 45

Ribonucleotide reductase is a highly regulated enzyme that provides the four deoxyribonucleotides required for DNA synthesis. Our studies showed that TGF-beta 1 treatment of BALB/c 3T3 mouse fibroblasts markedly elevated ribonucleotide reductase R2 mRNA levels, and also increased the half-life of R2 message by 4-fold from 1.5 h in untreated cells to 6 h in treated cells. We describe a novel 75 Kd sequence-specific cytoplasmic factor (p75) that binds selectively to a 83-nucleotide 3'-untranslated region of R2 mRNA and did not bind to the 5'UTR, the coding region of the R2 message or to the 3'UTRs of other mRNAs (from c-myc, GM-CSF and the iron responsive element from the transferrin receptor mRNA), or to the homopolymer poly(A) sequence. p75-RNA binding activity, which requires new protein synthesis, is not present in untreated cells, but is induced following TGF-beta 1 stimulation. The in vivo kinetics of appearance of p75 binding activity paralleled the accumulation of R2 mRNA. Insertion of the 3'-untranslated region into the chloramphenicol acetyltransferase (CAT) message confers TGF-beta 1 induced stability of RNA in stably transfected cells, while the same insert carrying a deletion of the 83-nucleotide fragment had little affect on RNA levels. Furthermore, in vitro decay reactions that contained the 83-nucleotide RNA or deletion of this fragment caused a significant decrease in TGF-beta 1 stabilization of R2 message. A model is presented of R2 message regulation in which TGF-beta 1 mediated stabilization of R2 message involves a specific interaction of a p75-trans-acting factor with a cis-element(s) stability determinant within the 83-nucleotide sequence which is linked to a reduction in the rate of R2 mRNA degradation.
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PMID:A novel transforming growth factor-beta 1 responsive cytoplasmic trans-acting factor binds selectively to the 3'-untranslated region of mammalian ribonucleotide reductase R2 mRNA: role in message stability. 823 29

Functional elements in the promoter region of the mouse granulocyte-macrophage colony stimulating factor (GM-CSF) gene were assessed by constructing chimeric promoters linked to the bacterial chloramphenicol acetyltransferase (CAT) gene and by employing a transient transfection assay of human T cell leukemia Jurkat cells. We previously reported that CLE2/GC-box (at positions -95 to -73, which is homologous to the NF-kappa B binding site) and CLE0 (at positions to -40) of the mouse GM-CSF promoter are essential for transcriptional activation in response to phorbol-12-myristate-13-acetate (PMA)/calcium ionophore (A23187). Here we show that CLE2/GC-box and the NF-kappa B binding motif are functionally interchangeable and that CLE2/GC-box and CLE0 as a unit activate the basic GM-CSF promoter in response to PMA/calcium signals. This unit is also capable of activating heterologous promoters in response to PMA/calcium signals. In addition, we show that Tax, the trans-activator encoded by human T cell leukemia virus type I (HTLV-I), activates the GM-CSF promoter via CLE2/GC-box without the involvement of CLE0. These results indicate that PMA/A23187-dependent and Tax-dependent activation of the GM-CSF gene proceeds through distinct mechanisms.
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PMID:Reconstitution of the functional granulocyte macrophage colony stimulating factor promoter: evidence for distinct activation mechanisms that mediate the response to phorbol ester/calcium and human T cell leukemia virus type I Tax signals. 849 21

Interferon-tau (oIFNtau), the major secretory product of ovine conceptuses between days 13 and 21 (day 0=day of estrus) of pregnancy, is implicated in the process of maternal recognition of pregnancy. Culturing of day-14 and day-16 conceptus tissues in the presence of human granulocyte macrophage-colony stimulating factor (hGM-CSF) or interleukin-3 (IL-3) produces a marked increase in oIFNtau mRNA and protein expression. Since GM-CSF and IL-3 are localized at the luminal and glandular epithelia of the ovine endometrium, maternally derived GM-CSF and IL-3 may affect conceptus production of oIFNtau in a paracrine manner. However, the molecular mechanisms by which endometrial GM-CSF and IL-3 up-regulate oIFNtau production have not been defined. As an initial investigation of the signaling pathway regulating the GM-CSF induction of the oIFNtau gene, day-16 conceptuses were treated with an inducer, phorbol 12-myristate 13-acetate (PMA) and an inhibitor, calphostin C of the protein kinase C (PKC) pathway. Treatment with either 150 units/ml hGM-CSF (P<0.01) or 10 nM PMA (P<0.05) resulted in a significant increase in oIFNtau mRNA expression. Pretreatment of conceptuses with 1 microM PMA for 12 h to produce PKC-deficient tissues or treatment with 50 mM calphostin C abolished the hGM-CSF-induced increase in oIFNtau mRNA. An in vitro expression system was established for the analysis of oIFNtau gene regulatory sequences. The oIFNtau010 gene has been isolated previously and found to be the principal oIFNtau gene up-regulated during the preimplantation period. 5'-Flanking regions of the oIFNtau010 gene, 2 kb and 0.8 kb, were cloned into a basic chloramphenicol acetyltransferase reporter plasmid. These oIFNtau010 promoter constructs, along with expression controls, were transfected into human choriocarcinoma cells (JAR and JEG3) and their responsiveness to hGM-CSF and second messenger system activators including PMA, calcium ionophore (A23187) and 8-bromo-cAMP were characterized. The oIFNtau010 promoter constructs were up-regulated by hGM-CSF and PMA treatments (P<0.01). Combined treatment with PMA and A23187 prevented the promoter activation seen with PMA alone. The conceptus culture data, along with the results from the transfection experiments, suggest that the stimulatory effect of GM-CSF on oIFNtau is mediated through the PKC second messenger system.
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PMID:Enhancement of ovine trophoblast interferon by granulocyte macrophage-colony stimulating factor: possible involvement of protein kinase C. 934 4

Human T-cell leukemia virus type-I (HTLV-I), the etiologic agent of adult T-cell leukemia (ATL) transforms human T cells both in vivo and in vitro. However, the long latency period between infection and development of ATL, as well as the small fraction of the infected population that actually develops this disease, suggest that factors in addition to the virus are involved in its pathogenesis. Mutation of tumor suppressor gene p53 has been found in both HTLV-I-transformed T-cell lines and ATL cases at relatively low frequency. However, increasing evidence supports p53 functional impairment in HTLV-I-transformed T cells. Tax, the major transactivator of HTLV-I, is critical for the initial events involved in transformation. We have considered the possibility that p53 may regulate transcription of viral and cellular genes important for viral replication and transformation. Inactivation of p53 function might then permit constitutive expression of these viral and cellular genes. We have investigated the effects of wild-type and mutant p53 on Tax-mediated activation of the HTLV-I long terminal repeat (LTR) and the promoters of several cellular genes including the interleukin (IL)-1alpha, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF ), and IL-2 receptor alpha chain gene. Jurkat, HuT78, and U937 cells were cotransfected with plasmids containing a chloramphenicol acetyltransferase (CAT ) reporter gene under viral or cellular promoter control and the Tax expression vector, in addition to vectors for a wild-type or mutant p53. Wild-type p53 is a potent repressor of viral and cellular activation by Tax. Mutations within p53 severely inhibit this downregulation. We also show that wild-type p53 suppresses transcription from the HTLV-I LTR in Jurkat-Tax, a T-cell line stably expressing Tax, and MT-2, a HTLV-I-transformed T-cell line. Wild-type, but not mutant, p53 interfered with the binding of TATA-binding protein (TBP) to the TATA motif of the HTLV-I LTR. These results suggest that p53 inactivation may lead to upregulation of viral and cellular genes and may also be important for establishment of productive viral infection and development of ATL.
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PMID:Repression of transcription from the human T-cell leukemia virus type I long terminal repeat and cellular gene promoters by wild-type p53. 938 10

We have recently shown that IL-3R occupancy activates a phosphatidylcholine-specific phospholipase C, and the sustained diacylglycerol accumulation subsequently activates protein kinase C (PKC). In human IL-3-dependent myeloid cells (TF-1), the novel PKCepsilon isoform regulates bcl-2 expression and cell survival. The report of a PKC activatable cAMP response element (CRE) in the bcl-2 promoter and a role for PKC in bcl-2 expression in B cells led us to the hypothesis that PKC phosphorylation activates transcription factor CREB after IL-3R engagement. We found that IL-3 and GM-CSF induced phosphorylation of CREB on Ser(133) in TF-1 cells, and this phosphorylation was blocked by two structurally unrelated classes of PKC inhibitors. An inhibitor of cyclic nucleotide-dependent kinases did not block this phosphorylation. IL-4, which is biologically active in these cells but does not use the beta common subunit, did not phosphorylate CREB on Ser(133). Inhibition of mitogen-activated protein kinase kinase activity also inhibited IL3-induced CREB phosphorylation. The PKC inhibitors, but not a cyclic nucleotide-dependent kinase inhibitor, blocked IL-3 activation of CRE-dependent transcription from an egr-1 promoter/chloramphenicol acetyltransferase (CAT) reporter construction transiently transfected into TF-1 cells. Finally, TF-1 cells stably overexpressing PKCepsilon, but not the delta isoform of PKC, enhanced CRE-dependent CAT expression from the promoter/reporter construction. Therefore, it is likely that a PKCepsilon kinase cascade resulting in CREB phosphorylation represents a novel signal transduction cascade for regulating cellular gene expression through the beta common cytokine receptor.
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PMID:betac cytokine receptor-induced stimulation of cAMP response element binding protein phosphorylation requires protein kinase C in myeloid cells: a novel cytokine signal transduction cascade. 1159 53