The latency-associated nuclear antigen of rhesus monkey rhadinovirus inhibits viral replication through repression of Orf5O/Rta transcriptional activation
The latency-associated nuclear antigen of rhesus monkey rhadinovirus inhibits viral replication through repression of Orf5O/Rta transcriptional activation
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DOI：
10.1128/jvi.79.5.3127-3138.2005
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发表时间：
2005-03-01
影响因子：
5.4
通讯作者：
Damania, B
中科院分区：
文献类型：
--
作者：
DeWire, SM;Damania, B
恒河猴疱疹病毒（RRV）是一种γ-2-疱疹病毒，与卡波西肉瘤相关疱疹病毒/人疱疹病毒-8密切相关。我们以前曾报道，RRV潜伏相关核抗原（R-LANA）的转录表达在恒河猴成纤维细胞裂解复制。在这篇文章中，我们报告了RRV潜伏培养系统的发展，并表明R-LANA特异性mRNA在潜伏期也有表达。我们已经表征了R-LANA蛋白，并证明它具有核斑点定位和具有同源二聚化的能力。当在恒河猴成纤维细胞中表达时，R-LANA可以抑制RRV体外裂解复制。我们研究了这种抑制背后的机制，发现虽然R-LANA本身对裂解启动子的影响很小，但它可以显著降低RRV Orf 50（Rta）的反式激活功能，这是主要的病毒转录因子。我们进一步表明，这种抑制的机制涉及组蛋白去乙酰化酶复合物（HDAC）的招募，因为R-LANA抑制Orf 50反式激活的能力是完全逆转的HDAC抑制剂阿司他丁A（TSA）的加入。我们还报告说，TSA单独可以显着重新激活潜伏感染细胞的RRV。我们认为R-LANA对RRV Orf 50反式激活的抑制作用有助于在裂解周期的后期下调早期基因的转录，并通过防止病毒再激活来帮助维持病毒潜伏期。
Rhesus monkey rhadinovirus (RRV) is a gamma-2-herpesvirus that is closely related to Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8. We have previously reported that the transcript for RRV latency-associated nuclear antigen (R-LANA) is expressed during lytic replication in rhesus fibroblasts. In this article, we report the development of a latent culture system for RRV and show that mRNA specific for R-LANA is expressed during latency as well. We have characterized the R-LANA protein and demonstrate that it exhibits a nuclear speckled localization and possesses the ability to homodimerize. When expressed in rhesus fibroblasts, R-LANA can inhibit RRV lytic replication in vitro. We have investigated the mechanism behind this inhibition and find that, while R-LANA itself has very little effect on lytic promoters, it can dramatically decrease the transactivation function of RRV Orf50 (Rta), which is the major viral transcription factor. We further show that the mechanism for this repression involves the recruitment of histone deacetylase complexes (HDACs), because R-LANA's ability to repress Orf50 transactivation is completely reversed by the addition of the HDAC inhibitor trichostatin A (TSA). We also report that TSA alone can significantly reactivate RRV from latently infected cells. We propose that the repressive effects of R-LANA on RRV Orf50 transactivation serve to downregulate the transcription of early genes at late times during the lytic cycle and also help to maintain viral latency by preventing viral reactivation.