Barry P A, Pratt-Lowe E, Unger R E, Luciw P A
Department of Medical Pathology, University of California, Davis 95616.
J Virol. 1991 Mar;65(3):1392-9. doi: 10.1128/JVI.65.3.1392-1399.1991.
It is hypothesized that the immediate-early (IE) gene products of human cytomegalovirus (CMV) and the transactivator (TAT) of human immunodeficiency virus type 1 (HIV-1) regulate HIV-1 gene expression through mechanisms involving host cell factors. By using transient transfection assays with the gene for chloramphenicol acetyltransferase (CAT) under the transcriptional control of the HIV-1 long terminal repeat (LTR), we examined transactivation of the LTR by plasmids that express either the HIV-1 gene for TAT or human CMV IE. The ratio of the level of transactivation by CMV IE to the level of transactivation by TAT varied up to 1,000-fold between cell types. The difference in the activities of these transactivators in various cell types was not a consequence of differential expression of the transactivator gene. Analysis of RNA species initiated in the HIV-1 LTR supports the conclusion that cellular factors regulate the level of elongation of the transcription complex on the LTR. Furthermore, evidence that in some cell types the predominant mechanism of transactivation by HIV-1 TAT involves posttranscriptional processes is presented.
据推测，人类巨细胞病毒（CMV）的立即早期（IE）基因产物和人类免疫缺陷病毒1型（HIV-1）的反式激活因子（TAT）通过涉及宿主细胞因子的机制调节HIV-1基因表达。通过使用在HIV-1长末端重复序列（LTR）转录控制下的氯霉素乙酰转移酶（CAT）基因进行瞬时转染分析，我们检测了表达HIV-1 TAT基因或人类CMV IE的质粒对LTR的反式激活作用。在不同细胞类型之间，CMV IE的反式激活水平与TAT的反式激活水平之比变化高达1000倍。这些反式激活因子在不同细胞类型中的活性差异并非反式激活因子基因差异表达的结果。对HIV-1 LTR起始的RNA种类的分析支持这样的结论，即细胞因子调节LTR上转录复合物的延伸水平。此外，还提供了证据表明，在某些细胞类型中，HIV-1 TAT反式激活的主要机制涉及转录后过程。
