Transcriptional regulation of the K1 gene product of Kaposi's sarcoma-associated herpesvirus
Transcriptional regulation of the K1 gene product of Kaposi's sarcoma-associated herpesvirus
复制标题
DOI：
10.1128/jvi.76.24.12574-12583.2002
复制
发表时间：
2002-12-01
影响因子：
5.4
通讯作者：
Damania, B
中科院分区：
文献类型：
--
作者：
Bowser, BS;DeWire, SM;Damania, B
卡波西肉瘤相关疱疹病毒（KSHV）的K1蛋白已被证明是一种转化蛋白，能够诱导啮齿动物成纤维细胞的形态学变化和病灶形成。K1可以激活B细胞受体（BCR）信号传导并上调NFAT和NF-κ B转录因子的活性。为了了解K1基因表达的调控，我们分析了K1基因上游的序列，以确定K1启动子元件。我们已经进行了cDNA末端的5'快速扩增以及核酸酶保护测定，以定位KSHV K1转录物的转录起始位点。K1转录起始位点位于翻译起始位点上游75 bp处。在293上皮细胞、KSHV阴性B细胞（BJAB）、KSHV阳性B细胞（BCBL-1）和KS肿瘤衍生内皮细胞（SLK-KS（-））中，对K1基因上游序列激活荧光素酶报告基因的能力进行了表征。我们发现，K1转录起始位点上游的125 bp序列足以在所有测试的细胞类型中完全激活荧光素酶报告基因。此外，病毒转录因子KSHV Orf 50/Rta能够在293、BJAB和BCBL-1细胞中进一步激活该启动子元件，但在SLK-KS（-）细胞中不激活。启动子构建体含有额外的序列上游的125 bp的元件没有显示进一步扩增的转录在存在或不存在的KSHV Orf 50。
The K1 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) has been shown to be a transforming protein capable of inducing morphological changes and focus formation in rodent fibroblasts. K1 can activate B-cell receptor (BCR) signaling and upregulate activity of the NFAT and NF-kappaB transcription factors. In order to understand the regulation of K1 gene expression, we have analyzed sequences upstream of the K1 gene to identify the K1 promoter element. We have performed 5' rapid amplification of cDNA ends as well as a nuclease protection assay to map the transcriptional start site of the KSHV K1 transcript. The K1 transcriptional start site lies 75 bp upstream of the translation start site. Sequences upstream of the K1 gene were characterized for their ability to activate a luciferase reporter gene in 293 epithelial cells, KSHV-negative B cells (BJAB), KSHV-positive B cells (BCBL-1), and KS tumor-derived endothelial cells (SLK-KS(-)). We found that a 125-bp sequence upstream of the K1 transcript start site was sufficient to fully activate the luciferase reporter gene in all cell types tested. In addition, the viral transcription factor KSHV Orf50/Rta was capable of further activating this promoter element in 293, BJAB, and BCBL-1 cells but not in SLK-KS(-) cells. Promoter constructs containing additional sequences upstream of the 125-bp element did not show further augmentation of transcription in the presence or absence of KSHV Orf50.