Zhang Hong-Sheng, Zhou Yue, Wu Meng-Ran, Zhou Hong-Sen, Xu Fei
Department of Virology and Pharmacology, College of Life Science and Bioengineering, Beijing University of Technology, District of Chaoyang, Beijing 100124, China.
Life Sci. 2009 Sep 23;85(13-14):484-9. doi: 10.1016/j.lfs.2009.07.014. Epub 2009 Aug 5.
Tat protein plays a pivotal role in both the human immunodeficiency virus type 1 (HIV-1) replication cycle and the pathogenesis of HIV-1 infection. Sirtuins 1 (SIRT1) is a possible candidate for redox modulation because its activity is regulated by nicotinamide adenine dinucleotide (NAD(+)) or NAD(+)/NADH ratio. The aim of the present study was to determine whether the redox status and SIRT1 expression are related to HIV-1 Tat protein-induced transactivation.
HeLa-CD4-long terminal repeat (LTR)-beta-gal (MAGI) cells were transfected with Tat plasmid. Tat-induced HIV-1 LTR transactivation was determined by MAGI cell assay. The NAD(+) or NADH levels and SIRT1 activity were measured. In addition, the protein expression of SIRT1 was assayed by western blotting.
Pretreatment with resveratrol increased intracellular NAD(+) levels and SIRT1 protein expression after Tat plasmid transfection in a concentration-dependent manner. Pretreatment with resveratrol attenuated Tat-induced HIV-1 transactivation in MAGI cells. These effects of resveratrol were largely abolished by knockdown of SIRT1 by short interfering RNA (siRNA). Pretreatment with nicotinamide, a SIRT1 inhibitor, potentiated Tat-induced HIV-1 transactivation in MAGI cells, and overexpression of SIRT1 attenuated Tat-induced HIV-1 transcription in MAGI cells.
Inhibition of SIRT1 activity by Tat is considered a critical step of Tat transactivation. Resveratrol and related compounds represent potential candidates for novel anti-HIV therapeutics.
Tat蛋白在人类免疫缺陷病毒1型（HIV-1）复制周期及HIV-1感染发病机制中均发挥关键作用。沉默调节蛋白1（SIRT1）是氧化还原调节的一个潜在候选分子，因为其活性受烟酰胺腺嘌呤二核苷酸（NAD(+)）或NAD(+)/NADH比值的调控。本研究旨在确定氧化还原状态及SIRT1表达是否与HIV-1 Tat蛋白诱导的反式激活有关。
用Tat质粒转染HeLa-CD4-长末端重复序列（LTR）-β-半乳糖苷酶（MAGI）细胞。通过MAGI细胞试验测定Tat诱导的HIV-1 LTR反式激活。检测NAD(+)或NADH水平及SIRT1活性。此外，通过蛋白质免疫印迹法检测SIRT1的蛋白表达。
白藜芦醇预处理以浓度依赖的方式增加了Tat质粒转染后细胞内NAD(+)水平及SIRT1蛋白表达。白藜芦醇预处理减弱了MAGI细胞中Tat诱导的HIV-1反式激活。通过小干扰RNA（siRNA）敲低SIRT1可很大程度上消除白藜芦醇的这些作用。SIRT1抑制剂烟酰胺预处理增强了MAGI细胞中Tat诱导的HIV-1反式激活，而SIRT1过表达减弱了MAGI细胞中Tat诱导的HIV-1转录。
Tat对SIRT1活性的抑制被认为是Tat反式激活的关键步骤。白藜芦醇及相关化合物是新型抗HIV治疗药物的潜在候选物。
