Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We had previously shown that chronically infected ACH-2 cells (HIVLAI) could be superinfected with HIVRF, that the frequency of superinfection increased with time, and that the transcription of the superinfecting virus exceeded that of the host HIVLAI provirus. In contrast, ACH-2 cells superinfected with a nef-substituted neomycin-resistant (proNEO) provirus were not detectable by DNA polymerase chain reaction (PCR) until geneticin (G418) was added, suggesting that the ability to propagate progressively in culture may be HIV strain specific. Clonal populations of ACH-2 superinfected with proNEO did not demonstrate preferential transcription of the superinfecting virus. However, clones of ACH-2 superinfected with HIVRF (ACH2/RF) showed a preponderance of HIVRF transcripts similar to that seen in bulk populations. Induction of the superinfecting virus by phorbol ester (PMA) occurred more rapidly than the hose provirus and did not equalize transcriptional activity. PCR-derived long terminal repeat (LTR) fragments and Tat cDNAs from A3.01 cells acutely infected with HIVRF or from ACH-2 cells were sequenced and tested for transactivation. The HIVLAI LTR was two to three times more Tat-responsive than the HIVRF LTR. TatRF was two to three times more transcriptionally active on either LTR than TatLAI. Demethylation with 5-azacytidine did not significantly affect HIV expression from the HIVLAI host provirus of superinfected ACH2/RF cell clones. These data suggest that the mechanism of preferential transcription in HIVRF superinfected ACH2/RF may be attributed to the Tat/TAR axis and the effect of the specific locus of host proviral integration.
 ...
PMID:Transcriptional effects of superinfection in HIV chronically infected T cells: studies in dually infected clones. 867 41

To understand the effects of the immunosuppressant cyclosporin A (CsA) on Ca2+-mediated intracellular signalling pathways in human peripheral blood mononuclear cells (PBMCs), we investigated its effects on the activity profiles of mitogen-activated protein kinase (MAPK) cascades. PBMCs, or subpopulations thereof, were simultaneously stimulated with a phorbol ester and the calcium ionophore ionomycin, in the presence or absence of therapeutic concentrations of CsA. In these primary human cells, CsA significantly inhibited PMA/ionomycin-mediated and ionomycin-mediated activation of the MAPK kinase MKK6, as well as its downstream kinases SAPK2a (p38alpha) and MAPKAP-K2. PMA/ionomycin treatment also mediated activation of SAPK1 (JNKs) which was inhibited by CsA. Treatment with ionomycin alone also resulted in CsA-sensitive activation of SAPK1. With regard to transcription factors targeted by the Ca2+-induced MAPK signalling network, we found CsA to inhibit the ionomycin-mediated phosphorylation of ATF2 at Thr71. We identified the heterodimeric transcription factor ATF2/CREB as constitutively binding to the essential cAMP response element (CRE) site within the Ca2+-regulated DNA polymerase beta promoter and contributing to the activation of this promoter. Our data implicate ATF2 phosphorylation status as a nuclear sensor within PBMCs that monitors converging intracellular Ca2+-signalling pathways.
 ...
PMID:Ca2+-induced p38/SAPK signalling inhibited by the immunosuppressant cyclosporin A in human peripheral blood mononuclear cells. 1051 4

This study assesses the ability of quantitative real-time PCR to measure the effects of virus DNA polymerase inhibitors on EBV DNA and late mRNAs syntheses in EBV-producing cell lines. In-house real-time quantitative PCRs were used to measure EBV DNA (thymidine kinase) and mRNAs (BLLF1 gene/gp350/220, BVRF2 gene/protease) in P3HR-1 and B95-8 cells induced for EBV production by PMA and exposed to ganciclovir, cidofovir and foscarnet. The calculated 50% effective concentrations (EC(50)) for viral DNA replication inhibition in P3HR-1 cells after 7 days of drug exposure were 0.28+/-0.06, 0.29+/-0.01 and 13.6+/-0.17 microg/mL for ganciclovir, cidofovir and foscarnet, respectively. The EC(50) for B95-8 cells were 0.44+/-0.02, 0.70+/-0.06 and 46.8+/-0.5 microg/mL, respectively. The quantitation of the late viral mRNAs showed a decrease of 79-89% in the mRNA amount after 4 days of antiviral treatment. Nevertheless, a substantial amount of mRNA still remained detectable after drug exposure. The real-time PCR is an improvement in the attempt to simplify EBV DNA-quantitation for antiviral assays. The quantitation of late mRNA does not appear as more informative than DNA quantitation for the assessment of the DNA polymerase inhibitor activity, but it may be useful to assess the antiviral activity of drugs acting by another mechanism.
 ...
PMID:Real-time quantitative PCR for assessment of antiviral drug effects against Epstein-Barr virus replication and EBV late mRNA expression. 1736 20