Department of Pathology and Animal Health, University of Naples Federico II, Naples, Italy.
J Cell Biochem. 2010 Oct 1;111(2):333-42. doi: 10.1002/jcb.22700.
Our previous studies have demonstrated that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increases Bovine Herpesvirus 1 (BHV-1) replication through a dose-dependent increase in cytopathy and increased viral titer. Furthermore, TCDD was able to trigger BHV-1-induced apoptosis by up-regulating the activation of initiator caspases 8 and 9, as well as of effector caspase 3. Since TCDD activates caspase 3 after 4 h of infection, we have hypothesized an involvement of BHV-1 infected cell protein 0 (bICP0) in this process. Such protein, the major transcriptional regulatory protein of BHV-1, has been shown to indirectly induce caspase 3 activation and apoptosis. In order to elucidate the role of bICP0 in this apoptotic pathway, here we have analyzed the effects of TCDD on bICP0 expression. Following infection of bovine cells with BHV-1, we detected apoptotic features already at 12 h after infection, only in TCDD exposed groups. Furthermore, in the presence of different doses of TCDD, we observed a time-dependent modulation and increase of bICP0 gene expression levels, as revealed by RT-PCR analysis. Western blot analysis and immunocytochemistry revealed that TCDD induced an increase of bICP0 protein levels in a dose-dependent manner, compared to unexposed groups. Moreover, Western blot analysis of nuclear and cytosolic fractions of infected cells revealed that TCDD anticipated the presence of bICP0 protein in the cytoplasm. In conclusion, both the increase of replication of BHV-1 and anticipation of BHV-1-induced apoptosis could be the result of a relationship between TCDD and bICP0.
我们之前的研究表明，2,3,7,8-四氯二苯并对二恶英（TCDD）通过剂量依赖性增加细胞病变和增加病毒滴度来增加牛疱疹病毒 1（BHV-1）的复制。此外，TCDD 能够通过上调起始半胱天冬酶 8 和 9 的激活以及效应半胱天冬酶 3 的激活来触发 BHV-1 诱导的细胞凋亡。由于 TCDD 在感染后 4 小时激活 caspase 3，我们假设 BHV-1 感染细胞蛋白 0（bICP0）参与了这一过程。这种蛋白是 BHV-1 的主要转录调节蛋白，已被证明可间接诱导 caspase 3 激活和细胞凋亡。为了阐明 bICP0 在这种凋亡途径中的作用，我们在这里分析了 TCDD 对 bICP0 表达的影响。在用 BHV-1 感染牛细胞后，我们仅在暴露于 TCDD 的组中观察到在感染后 12 小时就出现了凋亡特征。此外，通过 RT-PCR 分析，我们观察到在存在不同剂量的 TCDD 的情况下，bICP0 基因表达水平随时间呈时间依赖性调节和增加。Western blot 分析和免疫细胞化学显示，与未暴露组相比，TCDD 以剂量依赖的方式诱导 bICP0 蛋白水平增加。此外，对感染细胞的核和胞质部分的 Western blot 分析表明，TCDD 使 bICP0 蛋白提前存在于细胞质中。总之，BHV-1 复制的增加和 BHV-1 诱导的细胞凋亡的预期可能是 TCDD 和 bICP0 之间关系的结果。
