REGULATION OF VIRAL AND CELLULAR GENE EXPRESSON

人类T细胞嗜淋巴病毒I型(HTLV-I)与两种病毒有关 人类疾病、成人T细胞白血病(ATL)和热带痉挛 截瘫/HTLV-I相关性脊髓病(TSP/HAM)。税务蛋白 HTLV-I是一个40 kDa的转录激活子，它对 HTLV-I基因调控与病毒诱导的细胞转化。 通过与细胞转录因子的相互作用，Tax1调节 病毒和细胞基因表达的水平。税收本地化为 DNA通过与位点特异性激活物CREB的相互作用， 核因子-kappaB和SRF。有人建议，招募税务人员 与基础转录相互作用的DNA位置税 机械设备。基于几个独立的分析，我们已经证明 Tax和转录之间的物理和功能相互作用 因素，TFIIA。首先，税收被发现与35kD(阿尔法)相互作用 酵母双杂交系统中的TFIIA亚基。 重要的是，先前鉴定的两个Tax点突变株M32和M32 M41，被证明在税收激活的转录中存在缺陷，无法 在本实验中与TFIIA相互作用。第二，使用GST亲和力 结合实验表明，HALO-TFIIA与GST-TAX的相互作用是后者的20倍 高于GST-Tax M32激活突变体中的任何一个 或者是商品及服务税控制。第三，在感染HTLV-I的人T淋巴细胞中，Tax 和TFIIA在免疫共沉淀试验中被发现存在关联。 最后，观察到TFIIA对税收激活能力的影响 在体内和体外转录。体外转录 研究表明，在以下情况下，税收激活水平显著降低 使用TFIIA耗尽的细胞提取物。此外，人的转基因 TFIIA表达载体增强TFIIA激活的T淋巴细胞 HTLV-I-LTRCAT报告结构的转录。我们的研究 提示Tax与转录因子的相互作用 TFIIA可能在税收介导的转录激活中发挥作用。 在另一项研究中，对Jurkat T细胞cDNA文库进行了筛选 与HTLV-I Tax蛋白相互作用的蛋白质。这些研究 已经鉴定并表征了一种淋巴细胞特异性的Tax1结合 蛋白质，Trx。Trx与细胞内细胞周期蛋白B/cdc2复合体相互作用 以周期依赖的方式，提示在细胞周期调节中发挥作用。

Human T-cell lymphotropic virus type I (HTLV-I) is associated with two human diseases, adult T-cell leukemia (ATL) and tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). The Tax protein of HTLV-I is a 40 kDa transcriptional activator which is critical for HTLV-I gene regulation and viral-induced cellular transformation. Through interaction with cellular transcription factors, Tax1 regulates the level of viral and cellular gene expression. Tax is localized to the DNA through its interaction with the site-specific activators CREB, NF-kappaB and SRF. It has been suggested that the recruitment of Tax to the DNA positions Tax for interaction with the basal transcriptional machinery. Based on several independent assays, we have demonstrated a physical and functional interaction between Tax and the transcription factor, TFIIA. First, Tax was found to interact with the 35 kD (alpha) subunit of TFIIA in the yeast two-hybrid interaction system. Importantly, two previously characterized point mutants of Tax, M32 and M41, shown to be defective in Tax-activated transcription, were unable to interact with TFIIA in this assay. Second, using a GST affinity binding assay, the interaction of holo-TFIIA with GST-Tax was 20-fold higher than that observed with either the GST-Tax M32 activation mutant or the GST control. Third, in HTLV-I-infected human T-lymphocytes, Tax and TFIIA were found to associate in a coimmunoprecipitation assay. Finally, TFIIA was observed to influence the ability of Tax to activate transcription both in vivo and in vitro. In vitro transcription studies showed significantly reduced levels of Tax transactivation when using TFIIA-depleted cell extracts. In addition, transfection of human T-lymphocytes with TFIIA expression vectors enhanced Tax-activated transcription of an HTLV-I-LTR CAT reporter construct. Our study suggests that the interaction of Tax with the transcription factor TFIIA may play a role in Tax-mediated transcriptional activation. In a separate study, a Jurkat T-cell cDNA library was screened for proteins which interact with the HTLV-I Tax protein. These studies have identified and characterized a lymphocyte specific Tax1 binding protein, TRX. TRX interacts with the cyclin B/cdc2 complex in a cell cycle dependent manner, suggesting a role in cell cycle regulation.