Characterization of the influence of mediator complex in HIV-1 transcription.
HIV-1 exploits multiple host proteins during infection. siRNA-based screenings have identified new proteins implicated in different pathways of the viral cycle that participate in a broad range of cellular functions. The human Mediator complex (MED) is composed of 28 elements and represents a fundamental component of the transcription machinery, interacting with the RNA polymerase II enzyme and regulating its ability to express genes. Here, we provide an evaluation of the MED activity on HIV replication. Knockdown of 9 out of 28 human MED proteins significantly impaired viral replication without affecting cell viability, including MED6, MED7, MED11, MED14, MED21, MED26, MED27, MED28, and MED30. Impairment of viral replication by MED subunits was at a post-integration step. Inhibition of early HIV transcripts was observed by siRNA-mediated knockdown of MED6, MED7, MED11, MED14, and MED28, specifically affecting the transcription of the nascent viral mRNA transactivation-responsive element. In addition, MED14 and MED30 were shown to have special relevance during the formation of unspliced viral transcripts (p < 0.0005). Knockdown of the selected MED factors compromised HIV transcription induced by Tat, with the strongest inhibitory effect shown by siMED6 and siMED14 cells. Co-immunoprecipitation experiments suggested physical interaction between MED14 and HIV-1 Tat protein. A better understanding of the mechanisms and factors controlling HIV-1 transcription is key to addressing the development of new strategies required to inhibit HIV replication or reactivate HIV-1 from the latent reservoirs.
['Ruiz|Alba|A|', 'Pauls|Eduardo|E|', 'Badia|Roger|R|', 'Riveira-Muñoz|Eva|E|', 'Clotet|Bonaventura|B|', 'Ballana|Ester|E|', 'Esté|José A|JA|']
D015967:Gene Expression Regulation, Viral D015696:Gene Products, tat D015658:HIV Infections D015497:HIV-1 D006801:Humans D056892:Mediator Complex D011485:Protein Binding D014158:Transcription, Genetic
Transcription RNA Polymerase II Viral Transcription Tat Host Factor Human Immunodeficiency Virus (HIV) RNA Silencing RNAP II