Evidence for a bidirectional element located downstream from the herpes simplex virus type 1 latency-associated promoter that increases its activity during latency.
Evidence for a bidirectional element located downstream from the herpes simplex virus type 1 latency-associated promoter that increases its activity during latency.
复制标题
有证据表明，位于 1 型单纯疱疹病毒潜伏相关启动子下游的双向元件可在潜伏期间增加其活性。
DOI：
10.1128/jvi.74.8.3613-3622.2000
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发表时间：
2000
影响因子：
5.4
通讯作者：
Feldman,LT
中科院分区：
文献类型：
--
作者：
Berthomme,H;Lokensgard,J;Yang,L;Margolis,T;Feldman,LT
单纯疱疹病毒1型（HSV-1）体内潜伏感染的特征在于潜伏相关转录物（LAT）的组成性表达，其源自LAT启动子（EAT）。在试图确定LAT启动子的功能部分时，我们先前证明了携带LAT启动子本身的DNA片段3′的病毒能够在整个潜伏期内保持可检测的启动子表达，而不含该元件的病毒则不能（J. R. Lokensgard，H. Berthomme和L. T. Feldman，J. 71：6714-6719，1997）。因此，该元件被称为长期表达元件（LTE）。为了进一步研究LTE的作用，我们构建了含有DNA片段的质粒，所述DNA片段包含插入到合成内含子中的LTE，所述合成内含子位于HSV-I胸苷激酶启动子和LAT或HSV-1胸苷激酶启动子之间。神经元和非神经元细胞系的瞬时表达实验表明，LTE基因座具有增强子活性，不激活巨细胞病毒增强子，但激活启动子，如LAT启动子和胸苷激酶启动子。这两种启动子的增强发生在神经元和非神经元细胞系中。构建了含有增强子构建体的重组病毒，并且这些证明了增强子在病毒DNA存在时起作用，无论是用于培养中细胞的体外感染还是用于小鼠背根神经节中神经元的体内感染。在感染的小鼠背根神经节，有一个非常高的水平的启动子活性的神经元感染病毒轴承LAT启动子增强子，但这降低后的第2或3周。到感染后18天，携带无增强子的潜伏病毒的神经元未显示β-半乳糖苷酶（β-gal）染色，而携带含增强子的潜伏病毒的神经元持续长时间显示β-gal染色，延长至感染后至少6个月，这是检查的最长时间。
Herpes simplex virus type 1 (HSV-1) latent infection in vivo is characterized by the constitutive expression of the latency-associated transcripts (LAT), which originate from the LAT promoter (LAP). In an attempt to determine the functional parts of LAP, we previously demonstrated that viruses harboring a DNA fragment 3′ of the LAT promoter itself were able to maintain detectable promoter expression throughout latency whereas viruses not containing this element could not (J. R. Lokensgard, H. Berthomme, and L. T. Feldman, J. Virol. 71:6714–6719, 1997). This element was therefore called a long-term expression element (LTE). To further study the role of the LTE, we constructed plasmids containing a DNA fragment encompassing the LTE inserted into a synthetic intron between the reporterlacZgene and either the LAT or the HSV-1 thymidine kinase promoter. Transient-expression experiments with both neuronal and nonneuronal cell lines showed that the LTE locus has an enhancer activity that does not activate the cytomegalovirus enhancer but does activate the promoters such as the LAT promoter and the thymidine kinase promoter. The enhancement of these two promoters occurs in both neuronal and nonneuronal cell lines. Recombinant viruses containing enhancer constructs were constructed, and these demonstrated that the enhancer functioned when present in the context of the viral DNA, both for in vitro infections of cells in culture and for in vivo infections of neurons in mouse dorsal root ganglia. In the infections of mouse dorsal root ganglia, there was a very high level of promoter activity in neurons infected with viruses bearing the LAT promoter-enhancer, but this decreased after the first 2 or 3 weeks. By 18 days postinfection, neurons harboring latent virus without the enhancer showed no β-galactosidase (β-gal) staining whereas those harboring latent virus containing the enhancer continued to show β-gal staining for long periods, extending to at least 6 months postinfection, the longest time examined.