The latency-associated nuclear antigen encoded by Kaposi's Sarcoma-Associated herpesvirus activates two major essential Epstein-Barr virus latent promoters
The latency-associated nuclear antigen encoded by Kaposi's Sarcoma-Associated herpesvirus activates two major essential Epstein-Barr virus latent promoters
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DOI：
10.1128/jvi.75.19.9446-9457.2001
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发表时间：
2001-10-01
影响因子：
5.4
通讯作者：
Robertson, ES
中科院分区：
文献类型：
--
作者：
Groves, AK;Cotter, MA;Robertson, ES
由卡波西肉瘤相关疱疹病毒（KSHV）编码的潜伏相关核抗原（拉娜）在大多数KSHV感染的细胞和EB病毒（EBV）共感染的细胞中表达。在合并感染的体腔淋巴瘤（BCBLs）中，表达了B淋巴细胞转化所必需的EBV潜伏膜蛋白1（LMP 1）。EBNA 2通过与将EBNA 2拴系到其响应性启动子的细胞转录因子的特异性相互作用上调LMP 1和其他细胞基因的表达。在共感染的BCBL细胞中，未检测到EBNA 2，但组成型表达的拉娜含有提示潜在转录活性的基序。此外，最近的研究表明，拉娜能够激活细胞启动子。因此，我们研究了拉娜是否可以影响两个主要EBV潜伏启动子的转录。在这项研究中，我们证明，拉娜可以有效地反式激活LMP 1和C启动子在人B细胞系BJAB以及在人胚肾293细胞系。此外，我们证明了含有推定的亮氨酸拉链和富含谷氨酸的区域的拉娜的特定结构域在上调这些病毒启动子中是高度有效的，而氨基末端区域（435个氨基酸）在我们的测定中表现出很少或没有反式激活活性。我们还专门测试了LMP 1启动子元件的截短，并表明与包含两个重组信号结合蛋白JK结合位点的较大区域（-512至+40）相比，-204至+40区域的激活水平增加。较小的-204至+40启动子区含有Ets家族转录因子PU.1、转录激活因子/环AMP反应元件和Sp1的特异性结合位点，所有这些都已知作为转录激活因子起作用。因此，我们的数据表明拉娜在调节KSHV和EBV共感染细胞中的主要EBV潜伏启动子中的潜在作用。此外，拉娜可能能够在不存在EBNA 2的情况下激活病毒和细胞启动子的转录，这可能是通过与结合到-204至+40区域内的其同源序列的转录因子结合来实现的。这种病毒基因表达的调节对于这些DNA肿瘤病毒的持续存在至关重要，并且很可能参与介导这些共感染细胞中的致癌过程。
The latency-associated nuclear antigen (LANA) encoded by the Kaposi's sarcoma-associated herpesvirus (KSHV) is expressed in the majority of KSHV-infected cells and in cells coinfected with Epstein-Barr virus (EBV). In coinfected body cavity-based lymphomas (BCBLs), EBV latent membrane protein 1 (LMP1), which is essential for B-lymphocyte transformation, is expressed. EBNA2 upregulates the expression of LMP1 and other cellular genes through specific interactions with cellular transcription factors tethering EBNA2 to its responsive promoters. In coinfected BCBL cells, EBNA2 is not detected but LANA, which is constitutively expressed, contains motifs suggestive of potential transcriptional activity. Additionally, recent studies have shown that LANA is capable of activating cellular promoters. Therefore, we investigated whether LANA can affect transcription from two major EBV latent promoters. In this study, we demonstrated that LANA can efficiently transactivate both the LMP1 and C promoters in the human B-cell line BJAB as well as in the human embryonic kidney 293 cell line. Moreover, we demonstrated that specific domains of LANA containing the putative leucine zipper and the glutamic acid-rich region are highly effective in upregulating these viral promoters, while the amino-terminal region (435 amino acids) exhibited little or no transactivation activity in our assays. We also specifically tested truncations of the LMP1 promoter element and showed that the -204 to +40 region had increased levels of activation compared with a larger region, -512 to +40, which contains two recombination signal-binding protein JK binding sites. The smaller, -204 to +40 promoter region contains specific binding sites for the Ets family transcription factor PU.1, transcription activating factor/cyclic AMP response element, and Spl, all of which are known to function as activators of transcription. Our data therefore suggest a potential role for LANA in regulation of the major EBV latent promoters in KSHV- and EBV-coinfected cells. Furthermore, LANA may be able to activate transcription of viral and cellular promoters in the absence of EBNA2, potentially through association with transcription factors bound to their cognate sequences within the -204 to +40 region. This regulation of viral gene expression is critical for persistence of these DNA tumor viruses and most likely involved in mediating the oncogenic process in these coinfected cells.