Bovine Foamy Virus Transactivator BTas Interacts with Cellular RelB To Enhance Viral Transcription
Bovine Foamy Virus Transactivator BTas Interacts with Cellular RelB To Enhance Viral Transcription
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牛泡沫病毒反式激活蛋白 BTa 与细胞 RelB 相互作用以增强病毒转录
DOI：
10.1128/jvi.01036-10
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发表时间：
2010-11-01
影响因子：
5.4
通讯作者：
Qiao, Wentao
中科院分区：
文献类型：
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作者：
Wang, Jian;Tan, Juan;Qiao, Wentao
病毒是专性的细胞内寄生虫，依赖细胞机制进行有效的转录和复制。在以前的研究中，我们报道了牛泡沫病毒(BFV)能够通过其反式激活因子BTAS的作用来激活核因子kappaB(NF-kappa B)途径来增强病毒的转录。然而，核因子-kappa B用于增强BFV转录的机制仍然不清楚。为了解决这个问题，我们采用了酵母双杂交试验来筛选与BTAS相互作用的蛋白。我们发现，作为核因子-kappaB蛋白家族的一员，RelB与BTAS相互作用。我们在体外和体内证实了可能的RelB-BTAS相互作用，并确定了负责RelB-BTAS相互作用的蛋白质区域。利用荧光素酶报告实验，我们接下来证明了RelB增强了BFV的转录(BTAS诱导的长末端重复序列[LTR]反式激活)，这一过程既需要RelB-BTAS相互作用在细胞核中的定位，也需要RelB的Rel同源结构域。使用小干扰RNA(SiRNA)敲除细胞内源RelB蛋白显著减弱了BTAS诱导的LTR转录。染色质免疫沉淀(ChIP)分析结果表明，在BFV感染细胞中，内源性RelB与病毒LTR结合。综上所述，这些结果表明BFV参与了RelB蛋白作为BTAS的共反式激活因子来增强病毒转录。此外，我们的研究结果表明，BFV感染通过BTAS诱导的NF-kappa B激活上调细胞RelB的表达。因此，本研究证明了BFV存在一个正反馈电路，在该电路中，BFV通过RelB蛋白利用宿主的NF-kappa B途径进行有效的病毒转录。
Viruses are obligate intracellular parasites that depend on cellular machinery for their efficient transcription and replication. In a previous study we reported that bovine foamy virus (BFV) is able to activate the nuclear factor kappa B (NF-kappa B) pathway through the action of its transactivator BTas to enhance viral transcription. However, the mechanism used by NF-kappa B to enhance BFV transcription remains elusive. To address this question, we employed a yeast two-hybrid assay to screen for BTas-interacting proteins. We found that RelB, a member of NF-kappa B protein family, interacts with BTas. We confirmed the putative RelB-BTas interaction in vitro and in vivo and identified the protein regions responsible for the RelB-BTas interaction. Using a luciferase reporter assay, we next showed that RelB enhances BFV transcription (BTas-induced long terminal repeat [LTR] transactivation) and that this process requires both the localization of the RelB-BTas interaction in the nucleus and the Rel homology domain of RelB. The knockdown of the cellular endogenous RelB protein using small interfering RNA (siRNA) significantly attenuated BTas-induced LTR transcription. The results of chromatin immunoprecipitation (ChIP) analysis showed that endogenous RelB binds to the viral LTR in BFV-infected cells. Together, these results suggest that BFV engages the RelB protein as a cotransactivator of BTas to enhance viral transcription. In addition, our findings indicate that BFV infection upregulates cellular RelB expression through BTas-induced NF-kappa B activation. Thus, this study demonstrates the existence of a positive-feedback circuit in which BFV utilizes the host's NF-kappa B pathway through the RelB protein for efficient viral transcription.