Gröne M, Koch C, Grassmann R
Institut für Klinische und Molekulare Virologie der Universität Erlangen-Nürnberg, Germany.
Virology. 1996 Apr 15;218(2):316-25. doi: 10.1006/viro.1996.0200.
The human T-cell leukemia virus (HTLV-1) Rex protein is essential for the cytoplasmic accumulation of incompletely spliced transcripts that code for the viral structural proteins. In this study effects of Rex on the amounts of total, spliced and unspliced RNA from HTLV-1 were determined. In transfected fibroblasts Rex production resulted in reduced amounts of spliced RNA and increased quantities of unspliced RNA in the nucleus. However, the total amount of viral RNA was not affected and the stability of spliced transcripts was not changed, thus indicating that only the rate of splicing was reduced. Rex action also reduced splicing in immortalized human cord blood T-cells. However, the total amount of viral transcripts and the stability of unspliced RNA in these cells were also increased in the presence of Rex. This indicates that Rex also prevents the degradation of unspliced transcripts in T-cells. The changes in the relative amounts of spliced and unspliced RNA induced by Rex were observed not only in the cytoplasm but also in the nucleus. Thus Rex affects the nucleocytoplasmic transport, splicing and stability of HTLV-1 RNA in the nucleus. These observations may suggest that Rex directs the unspliced viral RNA to the cytoplasm via a nuclear compartment that is not accessible to splicing and degradation factors.
人类T细胞白血病病毒（HTLV - 1）的Rex蛋白对于编码病毒结构蛋白的不完全剪接转录本在细胞质中的积累至关重要。在本研究中，测定了Rex对HTLV - 1的总RNA、剪接RNA和未剪接RNA量的影响。在转染的成纤维细胞中，Rex的产生导致细胞核中剪接RNA量减少，未剪接RNA量增加。然而，病毒RNA的总量未受影响，剪接转录本的稳定性也未改变，因此表明只是剪接速率降低。Rex的作用还降低了永生化人脐血T细胞中的剪接。然而，在有Rex存在的情况下，这些细胞中病毒转录本的总量和未剪接RNA的稳定性也增加了。这表明Rex还能防止T细胞中未剪接转录本的降解。Rex诱导的剪接和未剪接RNA相对量的变化不仅在细胞质中观察到，在细胞核中也观察到。因此，Rex影响HTLV - 1 RNA在细胞核中的核质运输、剪接和稳定性。这些观察结果可能表明，Rex通过一个剪接和降解因子无法进入的核区室将未剪接的病毒RNA导向细胞质。
