Human protein Staufen-2 promotes HIV-1 proliferation by positively regulating RNA export activity of viral protein Rev

Abstract

BackgroundThe export of intron containing viral RNAs from the nucleus to the cytoplasm is an essential step in the life cycle of Human Immunodeficiency Virus-1 (HIV-1). As the eukaryotic system does not permit the transport of intron containing RNA out of the nucleus, HIV-1 makes a regulatory protein, Rev, that mediates the transportation of unspliced and partially spliced viral mRNA from the nucleus to the cytoplasm, thereby playing a decisive role in the generation of new infectious virus particles. Therefore, the host factors modulating the RNA export activity of Rev can be major determinants of virus production in an infected cell.ResultsIn this study, human Staufen-2 (hStau-2) was identified as a host factor interacting with HIV-1 Rev through affinity chromatography followed by MALDI analyses. Our experiments involving transient expressions, siRNA mediated knockdowns and infection assays conclusively established that hStau-2 is a positive regulator of HIV-1 pathogenesis. We demonstrated that Rev-hStau-2 interactions positively regulated the RNA export activity of Rev and promoted progeny virus synthesis. The Rev-hStau-2 interaction was independent of RNA despite both being RNA binding proteins. hStau-2 mutant, with mutations at Q314R-A318F-K319E, deficient of binding Rev, failed to promote hStau-2 dependent Rev activity and viral production, validating the essentiality of this protein-protein interaction. The expression of this positive regulator was elevated upon HIV-1 infection in both human T-lymphocyte and astrocyte cell lines.ConclusionsWith this study, we establish that human Staufen-2, a host factor which is up-regulated upon HIV-1 infection, interacts with HIV-1 Rev, thereby promoting its RNA export activity and progeny virus formation. Altogether, our study provides new insights into the emerging role of the Staufen family of mRNA transporters in host-pathogen interaction and supports the notion that obliterating interactions between viral and host proteins that positively regulate HIV-1 proliferation can significantly contribute to anti-retroviral treatments.

Modeling HIV-1 neuropathogenesis using three-dimensional human brain organoids (hBORGs) with HIV-1 infected microglia

“…Activated microglia and macrophages associated with HIV-1 neuropathogenesis are known to release various proinflammatory molecules. Among them, tumor necrosis factor (TNF-α) and interleukin-1 (IL-1β) play a central role in neuroinflammation 52 – 54 . Hence, we measured cumulative levels of TNF-α and IL-1β in supernatants from MG-hBORGs by ELISA.…”

“…This finding is consistent with the early findings conducted in post-mortem tissue from HIV-infected individuals correlating both, viral replication and TNF-α transcription 73 . Similarly, IL-1β is also elevated in the CNS during HIV-1 infection 52 . In our study, we observed similar IL-1β release from HIV-1-infected MG-hBORG over the course of the culture consistent with previous work of our group showing variation of IL-1β expression and release by monocyte-derived macrophages throughout the course of HIV-1 infection 55 .…”

Proteomics approach to understand reduced clearance of mycobacteria and high viral titers during HIV–mycobacteria co‐infection

“…Infectious HIV‐1 particles were prepared by transfection of proviral DNA pNL‐ADA8 into HEK293T cells by calcium phosphate method. Culture supernatants were collected at intervals of 24 h post‐transfection, filtered through 0.45 μM syringe filter (Millipore, USA), precipitated using Polyethylene glycol (Kutner et al , ; Banerjee et al , ) and quantified by HIV‐1 p24 ELISA kit (Advanced BioScience Laboratories Inc, USA) according to the manufacturer's protocol. Cells were infected with 30 ng ml −1 of p24 equivalents of HIV.…”

The importance of virion-incorporated cellular RNA-Binding Proteins in viral particle assembly and infectivity

“…Interestingly, STAU1 only modulates Gag assembly once the tail of Gag has anchored into the plasma membrane suggesting that STAU1 may play a role in ensuring the RNP is delivered to the membrane [ 86 ]. STAU2 has also been shown to promote the activity of HIV-1 Rev protein in exporting vRNA from the nucleus, along with DExH-box helicase 9 (DHX9) and ArfGAP with FG repeats 1 (AGFG1) [ [89] , [90] , [91] ]. Together, these studies suggest that Staufen proteins play crucial roles in the transport of HIV-1 RNPs from the nucleus to the plasma membrane for viral particle formation.…”