RBP-J (CSL) is essential for activation of the K14/vGPCR promoter of Kaposi's sarcoma-associated herpesvirus by the lytic switch protein RTA
RBP-J (CSL) is essential for activation of the K14/vGPCR promoter of Kaposi's sarcoma-associated herpesvirus by the lytic switch protein RTA
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DOI：
10.1128/jvi.78.13.6818-6826.2004
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发表时间：
2004-07-01
影响因子：
5.4
通讯作者：
Ganem, D
中科院分区：
文献类型：
--
作者：
Liang, YY;Ganem, D
卡波西肉瘤相关疱疹病毒（KSHV）基因产物病毒编码的G蛋白偶联受体（vGPCR）是细胞gpcr的同源物，已被认为在KSHV诱导的血管生成中发挥重要作用。最丰富的含有vGPCR的转录本是K14/vGPCR双链rna，在裂解再激活过程中被强烈诱导。在这里，我们表明控制该转录本的启动子对病毒裂解开关蛋白RTA的激活有强烈反应。通过缺失定位和扫描突变分析，我们在该启动子中确定了三个假定的RTA反应元件（A， B和C）。然而，在电泳迁移转移试验（EMSA）中，这些位点似乎都没有直接结合RTA。位点C对应于RBP-J的典型结合位点，RBP-J是一种序列特异性转录抑制因子，通常是Notch信号传导的靶点。R-BP-J可以结合RTA并将其招募到其同源识别位点；当这种情况发生时，RTA的激活功能可以缓解rbp - j介导的抑制，上调靶基因的表达。EMSA研究表明，位点A和C都能与R-BP-J结合；序列检测显示，位点A是已知RBP-J识别位点的一个新的功能变体。（位点B对应一种未知的宿主dna结合蛋白。）观察到K14/vGPCR启动子功能在RBP-J基因缺陷的细胞中被显著抑制，从而强调了位点A和C在体内的重要性。RBP-J对K14/vGPCR转录物的调控提出了Notch信号的其他调节剂可能能够在裂解KSHV复制的背景下诱导该RNA的表达的可能性。
The Kaposi's sarcoma-associated herpesvirus (KSHV) gene product virally encoded G protein-coupled receptor (vGPCR) is a homolog of cellular GPCRs and has been proposed to play important roles in KSHV-induced angiogenesis. The most abundant vGPCR-containing transcripts are K14/vGPCR bicistronic RNAs that are strongly induced during lytic reactivation. Here we show that the promoter governing this transcript is strongly responsive to activation by the viral lytic switch protein RTA. By deletion mapping and scanning mutation analyses, we have identified three putative RTA response elements (A, B, and C) in this promoter. However, none of these sites appear to directly bind RTA in electrophoretic mobility shift assays (EMSA). Site C corresponds to a canonical binding site for RBP-J, a sequence-specific transcriptional repressor that is normally the target of Notch signaling. R-BP-J can bind RTA and recruit it to its cognate recognition site; when this happens, the activation function of RTA can relieve RBP-J-mediated repression and upregulate expression of the targeted gene. EMSA studies reveal that both sites A and C can bind to R-BP-J; sequence inspection reveals that site A is a novel functional variant of known RBP-J recognition sites. (Site B corresponds to an as-yet-unknown host DNA-binding protein.) The importance of sites A and C in vivo is underscored by the observation that K14/vGPCR promoter function is dramatically inhibited in cells genetically deficient in RBP-J. The regulation of K14/vGPCR transcripts by RBP-J raises the possibility that other modulators of Notch signaling might be able to induce expression of this RNA outside the context of lytic KSHV replication.