Kubota S, Hatanaka M, Pomerantz R J
Dorrance H. Hamilton Laboratories, Center for Human Retrovirology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Virology. 1996 Jun 15;220(2):502-7. doi: 10.1006/viro.1996.0339.
The function of the Rex protein of human T-cell leukemia virus type I (HTLV-I) has been demonstrated to be very similar to the Rev protein of human immunodeficiency virus type 1 (HIV-1). Both of these retroviral regulatory proteins rescue unspliced viral RNAs from the nuclei of infected cells. The Rev protein of HIV-1 has been reported to shuttle between the nucleus/nucleolus and the cytoplasm. Here, we have found that Rex also relocated out of the nucleus in the presence of actinomycin D. This effect was demonstrated in dose- and time-course-dependent manners. In comparison with previous reports on HIV-1 Rev, these effects with Rex seemed to be similar, but less distinct, which may reflect precise differences in the subcellular localization and/or shuttling pathways of Rev and Rex. Interestingly, the endogenous truncated form of the Rex protein, p21x, significantly interfered with the intracellular translocation of Rex, when coexpressed in trans. As expression of p21x occurs in various HTLV-I-infected cells, p21x may play a role in the life-cycle of HTLV-I, through regulating the dynamic subcellular distribution of the viral trans-activator, Rex.
已证明人类I型T细胞白血病病毒（HTLV-I）的Rex蛋白功能与人类免疫缺陷病毒1型（HIV-1）的Rev蛋白非常相似。这两种逆转录病毒调节蛋白都能从受感染细胞的细胞核中拯救未剪接的病毒RNA。据报道，HIV-1的Rev蛋白在细胞核/核仁与细胞质之间穿梭。在此，我们发现，在放线菌素D存在的情况下，Rex也会从细胞核中重新定位出来。这种效应呈剂量和时间依赖性。与之前关于HIV-1 Rev的报道相比，Rex的这些效应似乎相似，但不太明显，这可能反映了Rev和Rex在亚细胞定位和/或穿梭途径上的精确差异。有趣的是，当共表达时，Rex蛋白的内源性截短形式p21x显著干扰了Rex的细胞内转运。由于p21x在各种HTLV-I感染细胞中都会表达，p21x可能通过调节病毒反式激活因子Rex的动态亚细胞分布，在HTLV-I的生命周期中发挥作用。
