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

A major metabolite of the vitamin D analogue 1 alpha-hydroxyvitamin D2 in human liver cells in culture has been identified as 1 alpha,24(S)-dihydroxyvitamin D2 [1 alpha,24(S)-(OH)2D2]. 1 alpha-Hydroxyvitamin D3 incubated with the same cells gives rise to predominantly 25- and 27-hydroxylated products. Our identification of 1 alpha,24(S)-dihydroxyvitamin D2 is based on comparisons of the liver cell metabolite with chemically synthesized 1 alpha,24(S)-(OH)2D2 and 1 alpha,24(R)-(OH)2D2 by using HPLC, GC and GC-MS techniques. The stereochemical orientation of the 24-hydroxyl group was inferred after X-ray-crystallographic analysis of the 24(R)-OH epimer. 1 alpha,24(S)-Dihydroxyvitamin D2 binds strongly to the vitamin D receptor and is biologically active in growth hormone and chloramphenicol acetyltransferase reporter gene expression systems in vitro, but binds poorly to rat vitamin D-binding globulin, DBP. We suggest that this metabolite, 1 alpha,24(S)-(OH)2D2, possesses the spectrum of biological properties to be useful as a drug in the treatment of psoriasis, metabolic bone disease and cancer.
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PMID:1 alpha,24(S)-dihydroxyvitamin D2: a biologically active product of 1 alpha-hydroxyvitamin D2 made in the human hepatoma, Hep3B. 764 51

Human immunodeficiency virus 1 (HIV1) infection is associated with severe psoriasis, B cell lymphoma, and Kaposi's sarcoma. A deregulated production of interleukin 6 (IL-6) has been implicated in the pathogenesis of these diseases. The molecular mechanisms underlying the abnormal IL-6 secretion of HIV1-infected cells may include transactivation of the IL-6 gene by HIV1. To test this hypothesis, we used the pIL6Pr-chloramphenicol acetyltransferase (CAT) plasmid, an IL-6 promoter-CAT construct, as a target of the transactivating function of the HIV1 TAT protein. By cotransfecting the pIL6Pr-CAT and the tat-expressing pSVT8 plasmid in MC3 B-lymphoblastoid or in HeLa epithelial cells, we observed that TAT transactivates the human IL-6 promoter. These results were confirmed when pIL6Pr-CAT was transfected in MC3 or HeLa cells that constitutively expressed the tat gene in a sense (pSVT8 cells) or antisense (pSVT10 cells) orientation. 5' deletion plasmids of pIL6Pr-CAT, in which regions at -658, -287, and -172 were inserted 5' to the cat gene, were transiently transfected in pSVT10 and pSVT8 cells and showed that TAT-induced activation of the IL-6 promoter required a minimal region located between -287 and -54 bp. Moreover, experiments with plasmids carrying the -658, -287, and -172 bp regions of the IL-6 promoter inserted downstream to a TAR-deleted HIV1-LTR identified the sequence of -172 to -54 as the minimal region of the IL-6 promoter required for TAT to transactivate the TAR-deleted HIV1-LTR. By DNA-protein binding experiments, tat-transfected cells expressed a consistent increase in kappa B and nuclear factor (NF)-IL-6 binding activity. Accordingly, the pDRCAT and IL-1REK9CAT, carrying tandem repeats of NF-kappa B or NF-IL6 binding motifs, respectively, were activated in TAT-expressing cells. The biological relevance of the TAT-induced IL-6 secretion was addressed by generating 7TD1 cells, an IL-6-dependent mouse cell line, stably expressing the tat gene. These tat-positive cells expressed the endogenous IL-6 gene, secreted high amounts of murine IL-6, and grew efficiently in the absence of exogenous IL-6. Moreover, the tat-positive 7TD1 cells sustained the growth of parental 7TD1 cells and showed a dramatic increase in their tumorigenic potency. These results suggest that TAT protein may play a role in the pathogenesis of some HIV1-associated diseases by modulating the expression of host cellular genes.
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PMID:The expression of the interleukin 6 gene is induced by the human immunodeficiency virus 1 TAT protein. 811 88

The multifunctional cytokine interleukin-6 (IL-6) plays a central role in host defence mechanisms and hematopoiesis. Furthermore, dysregulation of IL-6 gene expression is associated with the pathogenesis of various immunologically related diseases such as myeloma, systemic lupus erythematosus, rheumatoid arthritis, psoriasis and Kaposi's sarcoma. The regulation of IL-6 gene expression occurs mainly at transcriptional level, although mechanisms of post-transcriptional regulation have also been described. In the present study we demonstrate that in HeLa cells, induction of IL-6 by interferon-gamma (IFN-gamma) is transcriptionally controlled, as shown by run on assays and analysis of the IL-6 mRNA stability. Gel-retardation experiments using antibodies specific for factors of the IRF family identified four protein-DNA complexes, which bind to the interferon regulatory factor (IRF) binding site at position -267 to -254, in nuclear extracts from IFN-gamma treated cells. Furthermore, transient transfection analyses of the 5'-flanking region of IL-6 gene linked to the chloramphenicol acetyltransferase (CAT) reporter gene demonstrated that the -267 to -254 IRF site is necessary for IL-6 induction by IFN-gamma. However, transfection experiments in which IRF-1 and I kappa B alpha were overexpressed show that full-scale transcriptional activation of the IL-6 promoter directing CAT expression requires the co-operation between IRF-1 and NF-kappa B at a low constitutive level.
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PMID:Molecular mechanisms regulating induction of interleukin-6 gene transcription by interferon-gamma. 939 33

The combination of psoralens with UVA is used as PUVA therapy for psoriasis and other skin diseases. UVA-induced psoralen/DNA photoadducts act via suppression of DNA replication and cell proliferation, but do not sufficiently repress gene transcription. To explore whether PUVA may also be used for gene repression, psoralen was conjugated to a triplex-forming oligonucleotide (TFO) that targets a gene sequence of ICAM-1, a key molecule in cutaneous inflammation. Triplex formation between TFO and target sequence was detected by non-denaturing gel electrophoresis. UVA-irradiation induced psoralen cross-links at the triplex-duplex junction as verified by denaturing gel electrophoresis. When the target sequence was placed within the transcribed portion of the chloramphenicol acetyltransferase (CAT) gene, TFO inhibited CAT expression in A431 cells. Inhibition was sequence-specific, since a scrambled control oligonucleotide or mismatched or scrambled target sequences failed to inhibit CAT expression. Inhibition was not significant without UVA exposure, but was strongly enhanced by PUVA-mediated cross-links at the TFO target site. These results suggest that TFO may add a new quality to PUVA therapy by transcriptionally repressing pathogenically relevant genes, in addition to antiproliferative PUVA effects. TFO designed to repress only after PUVA activation may allow the development of a cutaneous organ specific strategy for gene repression.
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PMID:Triple helix-mediated inhibition of gene expression is increased by PUVA. 1514 Feb 12