The human immunodeficiency virus type 1 Tat protein up-regulates the promoter activity of the beta-chemokine monocyte chemoattractant protein 1 in the human astrocytoma cell line U-87 MG:: Role of SP-1, AP-1, and NF-κB consensus sites
The human immunodeficiency virus type 1 Tat protein up-regulates the promoter activity of the beta-chemokine monocyte chemoattractant protein 1 in the human astrocytoma cell line U-87 MG:: Role of SP-1, AP-1, and NF-κB consensus sites
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DOI：
10.1128/jvi.74.4.1632-1640.2000
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发表时间：
2000-02-01
影响因子：
5.4
通讯作者：
Garzino-Demo, A
中科院分区：
文献类型：
--
作者：
Lim, SP;Garzino-Demo, A
已经表明，人类免疫缺陷病毒1型（HIV-1）TAT蛋白可以特异性增强人类星形胶质细胞中单核细胞趋化蛋白1（MCP-1）的表达和释放。在这项研究中，我们显示了TAT诱导的MCP-1表达在转录水平上介导的证据。将全长TAT编码到人胶质母细胞瘤细胞系U-87 mg中的表达构建体的瞬时转染可从MCP-1启动子的共转染缺失构建体中增强报告基因活性。 HIV-1 TAT通过最小的构建体，该构建体包含213个核苷酸，在转化起始位点的上游。位置定向的诱变研究表明，SP1位点（位于核苷酸-123和-115之间）对于人MCP-1启动子的本构和TAT增强表达至关重要，因为该SP1位点的突变显着降低了报告基因表达中的sp1位点的突变。这两个实例。凝胶延迟实验进一步表明，TAT强烈增强了SP1蛋白与其在MCP-1启动子上的DNA元素的结合。此外，我们还观察到TAT处理后，转录因子和NF-KB与MCP-1启动子的结合活性增加。诱变研究表明，上游AP1位点和相邻的NF -KAPPA B位点（分别位于-128至-122和-150至-137），相反，在TAT介导的反式激活中起作用（-156至-150）似乎对启动子活性至关重要。我们假设TAT介导的SP1结合活性的增加增加了AP1和NF-KAPPA B的结合，从而导致MCP-1启动子的协同激活。
It has been shown that the human immunodeficiency virus type 1 (HIV-1) Tat protein can specifically enhance expression and release of monocyte chemoattractant protein 1 (MCP-1) from human astrocytes. In this study, we show evidence that Tat-induced MCP-1 expression is mediated at the transcriptional level. Transient transfection of an expression construct encoding the full-length Tat into the human glioblastoma-astrocytoma cell line U-87 MG enhances reporter gene activity from cotransfected deletion constructs of the MCP-1 promoter. HIV-1 Tat exerts its effect through a minimal construct containing 213 nucleotides upstream of the translational start site. Site-directed mutagenesis studies indicate that an SP1 site (located between nucleotides -123 and -115) is critical for both constitutive and Tat-enhanced expression of the human MCP-1 promoter, as mutation of this SP1 site significantly diminished reporter gene expression in both instances. Gel retardation experiments further demonstrate that Tat strongly enhances the binding of SP1 protein to its DNA element on the MCP-1 promoter. Moreover, we also observe an increase in the binding activities of transcriptional factors AP1 and NF-KB to the MCP-1 promoter following Tat treatment. Mutagenesis studies show that an upstream AP1 site and an adjacent NF-kappa B site (located at -128 to -122 and -150 to -137, respectively) play a role in Tat-mediated transactivation, In contrast, a further upstream AP1 site (-156 to -150) does not appear to be crucial for promoter activity. We postulate that a Tat-mediated increase in SP1 binding activities augments the binding of AP1 and NF-kappa B, leading to synergistic activation of the MCP-1 promoter.