12-O-tetradecanoylphorbol-13-acetate induces Epstein-Barr virus reactivation via NF-kappaB and AP-1 as regulated by protein kinase C and mitogen-activated protein kinase.
Signaling pathway components mediating Epstein-Barr virus (EBV) reactivation by 12-O-tetradecanoylphorbol-13-acetate (TPA) were characterized in terms of induction and modification of specific transacting factors. The consequences of protein kinase C (PKC) activation by TPA in inhibiting inducible nitric oxide synthase (iNOS) mRNA expression were analyzed in the EBV-infected gastric epithelial cell line GT38. Spontaneous expression of the EBV BZLF1 gene product ZEBRA became undetectable upon long-term culturing of GT38 cells, while iNOS mRNA expression increased. In such cells the PKC inhibitors 1-(5-isoquinolinesulphonyl)-2,5-dimethylpiperazine (H7) and staurosporine inhibited TPA-induced expression of BZLF1 and BRLF1 and reversed TPA-mediated inhibition of iNOS gene expression. The mitogen-activated protein kinase inhibitor PD98059 inhibited TPA-induced BZLF1 expression. Electrophoretic mobility shift assays demonstrated that transcription factors NF-kappaB and AP-1 were also activated by TPA in a time-dependent manner. The TPA-induced NF-kappaB activation was inhibited by prior treatment of the cells with the NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC). TPA-induced BZLF1 expression was also inhibited by the treatment with PDTC. Northern blot analyses characterized changes in levels of the c-jun and junB expressions of the AP-1 family. These results show that TPA induces EBV reactivation via NF-kappaB and AP-1 and that PKC is an important mediator in regulating gene expression leading to EBV reactivation after TPA treatment of GT38 cells.
Gao
X
X
Department of Biosignaling, Tottori University, Yonago, 683-8503, Japan.
Ikuta
K
K
Tajima
M
M
Sairenji
T
T
D002273:Carcinogens / Q000494:pharmacology*; D002460:Cell Line; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D016328:NF-kappa B / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects
D002273:Carcinogens; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate