Nitric Oxide Inhibits HIV Tat-Induced NF-κB Activation

• Published in: The American journal of pathology Vol. 155; no. 1; pp. 275 - 284
• Main Authors: Chen, Fei, Lu, Yongju, Castranova, Vince, Rojanasakul, Yon, Miyahara, Kaoru, Shizuta, Yutaka, Vallyathan, Val, Shi, Xianglin, Demers, Laurence M.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.07.1999; American Society for Investigative Pathology
• Subjects: Biological and medical sciences; Human viral diseases; Infectious diseases; Medical sciences; Regular; Viral diseases; Viral diseases of the lymphoid tissue and the blood. Aids; Cell culture; Activation; Transfection; Established cell line; Transcription factor NFκB; Immunopathology; Rodentia; Retroviridae; AIDS; Immune deficiency; Lentivirus; In vitro; Protein; Infection; Virus; Polymerase chain reaction; Vertebrata; Mammalia; Mouse; Viral disease; Animal; Nitric oxide; Human immunodeficiency virus; Molecular biology; Macrophage
• ISSN: 0002-9440; 1525-2191
• DOI: 10.1016/S0002-9440(10)65121-8

To evaluate the roles of nitric oxide (NO) on human immunodeficiency virus (HIV) Tat-induced transactivation of HIV long terminal repeat (HIV-LTR), we examined the effect of NO in the regulation of nuclear factor (NF)-κB, a key transcription factor involved in HIV gene expression and viral replication. In the present study, we demonstrate that HIV Tat activates NF-κB and that this activation can be attenuated by endogenous or exogenous NO. Inhibition of endogenous NO production with the NO synthase (NOS. inhibitor l-NMMA causes a significant increase in Tat-induced NF-κB activity. In addition, NO attenuates signal-initiated degradation of IκBα, an intracellular inhibitor of NF-κB, and blocks the DNA binding activity of the NF-κB p50/p50 homodimer and p50/p65 heterodimer. To determine how NO is induced by HIV Tat, reverse transcription polymerase chain reaction was used to demonstrate the induction of NOS-2 and NOS-3 mRNA by Tat. Although a putative NF-κB binding site was identified in the −74 GGAGAGCCCCC −64 region of the NOS-3 gene promoter, gel mobility shift assays and site-directed mutation analyses suggest that the putative NF-κB site is not of primary importance. Rather, several Sp-1 sites adjoining the putative NF-κB binding site in the promoter region of NOS-3 gene are required for the induction of NOS-3 gene expression by Tat.