Cellular and viral specificity of equine infectious anemia virus Tat transactivation.
Cellular and viral specificity of equine infectious anemia virus Tat transactivation.
复制标题
马传染性贫血病毒 Tat 反式激活的细胞和病毒特异性。
DOI：
10.1006/viro.1994.1226
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发表时间：
1994
期刊：
影响因子：
3.7
通讯作者：
Chesebro,B
中科院分区：
文献类型：
--
作者：
Maury,WJ;Carpenter,S;Graves,K;Chesebro,B
慢病毒在其生命周期中对功能TAT基因的依赖程度各不相同。为了开始了解控制马传染性贫血病毒(EIAV)反式激活的病毒和细胞参数，我们研究了TAT功能以及成功反式激活所需的TAT和LTR结构要求。从全长前病毒中检测病毒抗原需要表达EIAV Tat。利用马/鼠体细胞杂交种(SCH)，鉴定出一个支持EIAV反式激活的单一SCH系，表明特定的马染色体的存在为反式激活提供了所需的细胞因子。来自几个不同物种的转化细胞系也进行了测试，发现它们支持EIAV反式激活的能力不同。用允许反式激活EIAV的犬细胞系Cf2Th和不允许反式激活EIAV的人类细胞系HeLa定位在细胞特异性反式激活中重要的LTR和TAT区域。正如预期的那样，在所有研究的细胞系中，EIAV TAT反式激活都需要EIAV LTRR的R区。同样，HIV LTR的R区是HIV TAT反式激活所必需的。然而，U3区的组成也以细胞特异性的方式影响反式激活。在Cf2Th细胞中，用HIV U3序列替换EIAV U3序列导致高基础(非反式激活)表达，因此，在存在EIAV Tat的情况下，表达仅增加一倍。使用HIV TAT的类似研究表明，当LTR中存在EIAV或HIV U3序列时，Cf2Th细胞中发生反式激活。相反，HIV或EIAV Tat在HeLa细胞中的反式激活需要HIV增强子序列的存在。这些发现表明，在某些细胞系中发生反式激活的能力可能涉及细胞特异性转录因子和TAT激活结构域之间的相互作用。对于其他细胞系的反式激活，TAT似乎需要更多与EIAV和HIV U3序列相互作用的普遍因子。
Lentiviruses vary in their dependence on a functional tat gene during their viral life cycle. To begin to understand the viral and cellular parameters controlling equine infectious anemia virus (EIAV) transactivation, we investigated Tat function and Tat and LTR structural requirements necessary for successful transactivation. EIAV Tat expression was required for detection of viral antigens from a full-length provirus. The level of transactivation by EIAV Tat as measured by LTR-CAT assays correlated well with viral antigen expression, Using horse/mouse somatic cell hybrids (SCH), a single SCH line which supported EIAV transactivation was identified, indicating that the presence of specific horse chromosomes provided cellular factors required for transactivation. Transformed cell lines from several different species were also tested and found to differ in their ability to support EIAV transactivation. A canine cell line, Cf2Th, which was permissive for EIAV transactivation, and a human cell line, HeLa, which was not permissive for EIAV transactivation, were used to map regions of the LTR and Tat that were important in cell-specific transactivation. As expected, the R region of EIAV LTR was required for transactivation by EIAV Tat in all cell lines studied. Similarly, the R region of HIV LTR was necessary for transactivation by HIV Tat. However, the composition of the U3 region also influenced transactivation in a cell-specific manner. In Cf2Th cells, replacement of EIAV U3 sequences with HIV U3 sequences resulted in high basal (nontransactivated) expression, and as a result, only a twofold increase in expression was observed in the presence of EIAV Tat. Similar studies using HIV Tat demonstrated that transactivation occurred in Cf2Th cells when either EIAV or HIV U3 sequences were present in the LTR. In contrast, transactivation by either HIV or EIAV Tat in HeLa cells required the presence of HIV enhancer sequences. These findings suggested that the ability of transactivation to occur in some cell lines may involve interactions between cell-specific transcription factors and the activation domain of Tat. For transactivation in other cell lines, Tat appeared to require more ubiquitious factors that interact with both EIAV and HIV U3 sequences.