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HIV-1 Nef protein inhibits brefeldin A mediated apoptosis in primary human macrophages

This paper is available in a repository.
This paper is available in a repository.

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Abstract

Human immunodeficiency virus type 1(HIV-1) primarily targets macrophages and CD4+ T cells. HIV-1 Nef protein is expressed during early phase of infection and influences nearly all stages of viral growth kinetics. Notably, Nef protects macrophages from stress induced apoptosis triggered upon HIV-1 infection. However, mechanism responsible for Nef induced anti-apoptotic behavior in stressed macrophages is poorly understood. Of note, eukaryotic translation elongation factor 1A (eEF1A) besides playing an important role in protein synthesis,it has been also reported to play a significant role in apoptosis. In the present study we evaluate the role of eEF1A and Nef in primary human monocyte derived macrophages (MDMs). Using nuclear retention and RNAi experiments, we found that cytoplasmic relocalization of eEF1A in Nef treated MDMs was mediated by exportin-t (Exp-t). Not surprisingly, we detected the presence of tRNA in Nef/eEF1A complex. In addition, nucleocytoplasmic relocalization of the Nef/eEF1A complex resulted in inhibition of stress induced apoptosis of MDMs triggered by brefeldin A treatment. Increased in nucleocytoplasmic transport of eEF1A coupled with the decrease in release of mitochondrial cytochrome cand increased tRNA binding to the cytochrome c collectively resulted in caspase inactivation. Taken together, our results demonstrate that HIV-1 Nef induces anti-apoptotic characteristics in stressed MDMs through the nucleocytoplasmic relocalization of eEF1A andtRNAs. These observationsprovide one possible mechanism of the development and maintenance of viral reservoirs in HIV-1 infected individuals.