HIV: pesquisa atual
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Nf-κb-Dependent Inhibition of HIV-1 Transcription by Withaferin A

Tao Shi, Emmanuelle Wilhelm, Brendan Bell and Nancy Dumais

Despite the remarkable progress made in suppressing HIV-1 infection, antiretroviral drugs are still often inaccessible in developing countries, and there is an urgent need for cheaper and alternative drugs. HIV-1 replication is triggered by the activation of the long terminal repeat (LTR) promoter, which contains two binding sites for the transcription factor nuclear factor κB (NF-κB). Withaferin A (WA), a steroidal lactone isolated from the Indian medicinal plant Withania somnifera, has been found to have significant pharmacological effects on the regulation of immune response. Recent studies have demonstrated that the anti-inflammatory properties of WA are mainly due to its inhibition of the NF-κB pathway. In the present study, we demonstrate that WA represses HIV-1 LTR transcription and viral replication through NF-κB inhibition. The human lymphocyte T cell line Jurkat E6.1 was treated with WA and infected with wild-type pseudotyped HIV- 1 particles or mutant viruses containing inactive κB sites. Then, the effect of WA on HIV-1 replication was evaluated by the measurement of reporter activity. Electrophoretic mobility shift assays and Western blots analysis were also performed to study the impact of WA on NF-κB. We found that WA inhibited the transcription of wild-type pseudotyped viruses in single-round infection assays, whereas mutant viruses containing inactive κB sites showed a reduced response to WA. Moreover, we found that WA directly or indirectly inhibits NF-κB nuclear translocation, including RelA and p50 subunits. However, the degradation of inhibitory protein IκB-α was not prevented by WA. Taken together, our results suggest that WA inhibits HIV-1 transcription in human Jurkat E6.1 lymphocyte T cells through the NF-κB pathway.