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)

Activation of the transcription factor NF-kappaB by extracellular signals involves its release from the inhibitor protein IkappaBalpha in the cytoplasm and subsequent nuclear translocation. NF-kappaB can also be activated by the anticancer agent camptothecin (CPT), which inhibits DNA topoisomerase (Topo) I activity and causes DNA double-strand breaks during DNA replication to induce S phase-dependent cytotoxicity. Here we show that CPT activates NF-kappaB by a mechanism that is dependent on initial nuclear DNA damage followed by cytoplasmic signaling events. NF-kappaB activation by CPT is dramatically diminished in cytoplasts and in CEM/C2 cells expressing a mutant Topo I protein that fails to bind CPT. This response is intensified in S phase cell populations and is prevented by the DNA polymerase inhibitor aphidicolin. In addition, CPT activation of NF-kappaB involves degradation of cytoplasmic IkappaBalpha by the ubiquitin-proteasome pathway in a manner that depends on the IkappaB kinase complex. Finally, inhibition of NF-kappaB activation augments CPT-induced apoptosis. These findings elucidate the progression of signaling events that initiates in the nucleus with CPT-Topo I interaction and continues in the cytoplasm resulting in degradation of IkappaBalpha and nuclear translocation of NF-kappaB to attenuate the apoptotic response.
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PMID:NF-kappaB activation by camptothecin. A linkage between nuclear DNA damage and cytoplasmic signaling events. 1073 98

Resveratrol inhibits herpes simplex virus (HSV) replication by an unknown mechanism. Previously it was suggested that this inhibition may be mediated through a cellular factor essential for HSV replication [Docherty, J.J., Fu, M.M., Stiffler, B.S., Limperos, R.J., Pokabla, C.M., DeLucia, A.L., 1999. Resveratrol inhibition of herpes simplex virus replication. Antivir. Res. 43, 145-155]. After examining numerous cellular factors, we report that resveratrol suppresses NF-kappaB (NF-kappaB) activation in HSV infected cells. Reports have indicated that HSV activates NF-kappaB during productive infection and this may be an essential aspect of its replication scheme [Patel, A., Hanson, J., McLean, T.I., Olgiate, J., Hilton, M., Miller, W.E., Bachenheimer, S.L., 1998. Herpes simplex type 1 induction of persistent NF-kappa B nuclear translocation increases the efficiency of virus replication. Virology 247, 212-222; Gregory, D., Hargett, D., Holmes, D., Money, E., Bachenheimer, S.L., 2004. Efficient replication by herpes simplex virus type 1 involves activation of the IkappaB kinase-IkappaB-RelA/p65 pathway. J. Virol. 78, 13582-13590]. Electromobility shift assays determined that resveratrol, in a dose dependent and reversible manner, suppressed activation of NF-kappaB in Vero cells infected with HSV-1, HSV-2 and acyclovir resistant HSV-1. Furthermore, resveratrol did not protect IkappaBalpha, a cytoplasmic NF-kappaB inhibitor, from degradation in HSV-1 infected cells. Immunohistochemical studies demonstrated that RelA/p65, a component of the dimeric NF-kappaB complex, translocated to the nucleus of HSV-1 infected cells in the presence of resveratrol. Finally, direct effects on viral transcription and DNA synthesis were evaluated. Real-time RT-PCR analysis showed that resveratrol treatment of infected cells resulted in reductions of mRNA for ICP0, ICP4, ICP8 and HSV-1 DNA polymerase by 2.1-, 3.3-, 3.8- and 3.1-fold, respectively. Plus, mRNA for glycoprotein C, an HSV late gene, was completely absent in the presence of resveratrol. Lastly, quantitative PCR showed that resveratrol significantly blocked HSV DNA synthesis. Cumulatively, these data indicate that resveratrol (i) suppresses HSV induced activation of NF-kappaB within the nucleus and (ii) impairs expression of essential immediate-early, early and late HSV genes and synthesis of viral DNA.
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PMID:Resveratrol suppresses nuclear factor-kappaB in herpes simplex virus infected cells. 1687 85