Mechanisms regulating HIV-1 gene expression

HIV-1 基因表达的调节机制

• 批准号: 6510749
• 负责人: Noelle Sevilir Williams
• 金额: $ 29.64万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6510749
• 关键词: cyclin dependent kinase; enzyme activity; gene expression; genetic transcription; host organism interaction; human immunodeficiency virus 1; laboratory rabbit; phosphorylation; virus protein

DESCRIPTION (provided by applicant): The Tat protein is a viral transactivator that is activates HIV-1 gene expression by increasing the ability of RNA polymerase II to efficiently undergo transcriptional elongation. Increases in RNA polymerase II processivity can be modulated by altering the phosphorylation state of RNA polymerase II and by the association of specific elongation factors with the transcription complex. Studies indicate that Tat-activation of HIV- 1 transcription elongation is mediated by its binding to TAR RNA in conjunction to the pTEF-b kinase complex comprised of cyclin Ti and CDK9 to increase the activity of the elongation factors SPT4/SPT5. The mechanism by which the Tat/pTEF-b complex stimulates RNA polymerase IL processivity in conjunction with SPT4/SPT5 remains to be determined. In this proposal, we utilize a number of approaches in order to better understand the mechanism by which Tat increases HIV- 1 transcriptional elongation. We have used biochemical fractionation to identify two novel factors that bind to cyclin Ti and SPT5. In addition, we have found that CDK9 kinase activity is altered by changes in the cell cycle suggesting links between the regulation of the cell cycle and cellular gene expression. The changes in CDK9 kinase activity correlate with increases in the phosphorylation state of both RNA polymerase II and SPT5. Finally, we have used RINA interference, a well characterized method to interrupt specific gene function in lower species, to begin to define the in vivo transcriptional pathways involved in Tat activation. The objectives of this proposal are to elucidate the specific steps that are involved in Tat-activation of HIV- 1 gene expression. The specific aims are: (1) To characterize the function of cellular proteins JBP 1 and PP2C that are associated with SPT4/SPT5 and cyclin T1/CDK9. (2) To understand the mechanisms regulating the changes in CDK9 kinase activity during the cell cycle. (3) To determine the role of CDK9/ cyclin Ti phosphorylation of SPT5 on regulating its ability to stimulate transcriptional elongation. (4) To use RNA interference to define the transcriptional pathways that are involved in regulating Tat-activation. These studies will address the different mechanisms involved in regulating the ability of Tat to activate HIV- 1 gene expression.

描述（由申请人提供）：TAT蛋白是病毒式反式激活剂 这是通过提高RNA的能力来激活HIV-1基因表达 聚合酶II有效地经历转录伸长。增加 RNA聚合酶II加工性可以通过改变磷酸化来调节 RNA聚合酶II的状态和特定伸长的关联 转录复合物的因素。研究表明 HIV-1转录伸长是由其与Tar RNA的结合介导的 与Cyclin Ti和CDK9组成的PTEF-B激酶复合物的结合 增加伸长因子SPT4/SPT5的活性。机制 TAT/PTEF-B复合物刺激了RNA聚合酶IL的加工性 与SPT4/SPT5的结合尚待确定。 在此提案中，我们利用多种方法来更好 了解TAT增加HIV-1转录的机制 伸长。我们已经使用生化分级来识别两个新颖 与细胞周期蛋白Ti和SPT5结合的因素。此外，我们发现CDK9 激酶活性因细胞周期的变化而改变了暗示联系 在细胞周期的调节和细胞基因表达之间。这 CDK9激酶活性的变化与磷酸化的增加相关 RNA聚合酶II和SPT5的状态。最后，我们使用了Rina 干扰，一种特征的中断特定基因功能的方法 在较低的物种中，开始定义体内转录途径 参与TAT激活。 该提案的目标是阐明 参与HIV-1基因表达的TAT激活。具体目的是： （1）表征细胞蛋白JBP 1和PP2C的功能 与SPT4/SPT5和Cyclin T1/CDK9相关。 （2）了解机制 调节细胞周期中CDK9激酶活性的变化。 （3）到 确定SPT5的CDK9/ Cyclin Ti磷酸化在调节其调节方面的作用 刺激转录伸长的能力。 （4）使用RNA干扰 定义与调节有关的转录途径 tat激活。这些研究将解决涉及的不同机制 调节TAT激活HIV-1基因表达的能力。