Jordan A, Defechereux P, Verdin E
Gladstone Institute of Virology and Immunology and Department of Medicine, University of California, San Francisco, CA 94141, USA.
EMBO J. 2001 Apr 2;20(7):1726-38. doi: 10.1093/emboj/20.7.1726.
Because of the heterogeneity of chromatin, the site of integration of human immunodeficiency virus (HIV) in the genome could have dramatic effects on its transcriptional activity. We have used an HIV-1-derived retroviral vector, in which the green fluorescent protein is under the control of the HIV promoter, to generate by infection 34 Jurkat clonal cell lines each containing a single integration of the HIV-1 vector. In the absence of Tat, a 75-fold difference in expression level between the highest and lowest expressing clones was observed. Basal promoter activity was low in 80% of the clones and moderate to high in the remaining 20% of clones. We found that differences in expression levels are due to the integration site and are not controlled by DNA methylation or histone acetylation. Tat activated transcription in each clone, and an inverse correlation was observed between basal transcriptional activity and inducibility by Tat. These observations demonstrate that the chromatin environment influences basal HIV gene expression and that the HIV Tat protein activates transcription independently of the chromatin environment.
由于染色质的异质性，人类免疫缺陷病毒（HIV）在基因组中的整合位点可能对其转录活性产生显著影响。我们使用了一种源自HIV-1的逆转录病毒载体，其中绿色荧光蛋白受HIV启动子控制，通过感染产生了34个Jurkat克隆细胞系，每个细胞系都含有单个HIV-1载体整合。在没有Tat的情况下，观察到最高表达克隆和最低表达克隆之间的表达水平存在75倍的差异。80%的克隆中基础启动子活性较低，其余20%的克隆中基础启动子活性中等至高。我们发现表达水平的差异是由于整合位点造成的，不受DNA甲基化或组蛋白乙酰化的控制。Tat在每个克隆中激活转录，并且观察到基础转录活性与Tat诱导性之间呈负相关。这些观察结果表明染色质环境影响HIV基础基因表达，并且HIV Tat蛋白独立于染色质环境激活转录。
