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)

Primary human macrophages induced to differentiate through contact with autologous activated nonadherent cells were used to investigate the transcriptional mechanisms involved in reactivation of human immunodeficiency virus (HIV) replication. Through transient transfection experiments with an HIV long terminal repeat (LTR)-chloramphenicol acetyltransferase reporter construct, we show that macrophage differentiation results in a 20-fold upregulation of basal LTR activity. To identify sequence elements responsive to the differentiation process, point mutations introduced into the LTR were tested in differentiated and undifferentiated macrophages. Several elements were identified as positive regulators of basal transcription. TATA, Sp1, and NF-kappa B binding sites were the most influential. The low-affinity site for LBP-1 (UBP-1) functioned as a negative regulator of LTR activity in undifferentiated macrophages, but this influence was lost upon differentiation. When tat was cotransfected into the expression system, the requirement for LTR elements identified as important for positive regulation of basal transcription remained in undifferentiated macrophages. Interestingly, however, the mutations in positive control elements which debilitated activity in undifferentiated macrophages had no effect on LTR activity in differentiated macrophages. Thus, it appears that while HIV-LTR activity is highly dependent on cellular transcription factors in undifferentiated cells, in differentiated macrophages the viral protein Tat confers pliability on the LTR and facilitates autonomy from absolute cellular control mechanisms. In vivo, release from either positive or negative regulation via cellular proteins may facilitate reactivation of HIV in macrophages.
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PMID:Differential role of long terminal repeat control elements for the regulation of basal and Tat-mediated transcription of the human immunodeficiency virus in stimulated and unstimulated primary human macrophages. 825 41

IE1 and IE3 mRNAs and their protein products (IE110 and IE175, respectively) were detected in HSV-1-infected U937 cells at 4-15 hours postinfection. In transient expression assays with infectious HIV or an HIV-LTR-directed chloramphenicol acetyltransferase construction (HIV-LTRcat), HSV-1 caused HIV activation (86.7% +/- 6.4% conversion). Electrophoretic mobility shift assays with DNA sequences that encompass the LBP-1 binding site revealed increased levels of DNA-protein complex formation with nuclear extracts from HSV-1 infected as compared with uninfected U937 cells. Novel bands were not seen. HSV-1 mutants respectively deleted in IE110 (dl1403) or IE175 (d120) activated HIV as well as wild-type virus. However, HSV-1-mediated activation was inhibited (26% conversion) by simultaneous treatment with oligonucleoside methylphosphonates (ONMP) that specifically inhibit expression of IE110 (IE1TI) or IE175 (IE3TI). ONMP did not inhibit activation when used individually (83.8% and 67.8% conversion with IETI1 and IE3TI, respectively). Combinations of mutant ONMP that do not inhibit IE110 or IE175 expression did not reduce the levels of HSV-1-mediated activation. These findings suggest that HSV genes IE1 and IE3 can independently activate HIV in monocytic cells and ONMP that target HSV IE genes can be used to inhibit HIV activation.
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PMID:Herpes simplex virus-mediated activation of human immunodeficiency virus is inhibited by oligonucleoside methylphosphonates that target immediate-early mRNAs 1 and 3. 878 93

The 5'-upstream region of the rat phospholipase C-beta 3 gene (PLC-beta 3) has been cloned and characterized. Sequence analysis of the 5'-upstream region showed that it contains a GC-rich region (-166 to +1: 79%) and multiple binding sites for the transcription factors Sp1, AP-1 and AP-2, but does not contain a canonical TATA box. Primer extension analysis of total RNA isolated from rat glial cell C6Bul revealed that single transcription start point (tsp) is located at an initiator (Inr) element similar to that found in the HIV promoter. Gel mobility shift and competitive mobility shift assays indicated that this Inr element forms a DNA-protein complex with the HIV Inr-binding protein, LBP-1/CP2 or a homologue. In order to localize functional elements of the 5'-upstream region of the rat PLC-beta 3 gene, 5'-deletion fragments were cloned into a chloramphenicol acetyltransferase (CAT) reporter vector. Transient transfection analyses of the 5'-deletion mutants identified a crucial promoter element located at -128 to -14. Supershift mobility assays, site-directed mutagenesis and DNase I footprints indicated that Sp1 binds to three GC boxes within the sequence between -128 and -14 of the PLC-beta 3 promoter. Transient transfection analyses of promoter constructs containing site-specific mutation(s) of these three GC boxes demonstrated that two GC boxes, located proximal to the tsp, are important elements for normal promoter activity.
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PMID:The 5'-upstream region of the rat phospholipase C-beta 3 gene contains two critical Sp1 sites and an HIV Inr-like element. 933 46