Nuclear Factor 90, a cellular dsRNA binding protein inhibits the HIV Rev-export function

Silvio Urcuqui-Inchima,Georges St-Laurent,Maria Eugenia Castaño,Danièle Hernandez-Verdun,Ajit Kumar

doi:10.1186/1742-4690-3-83

Silvio Urcuqui-Inchima, Georges St-Laurent + Show 3 more

Open Access

PDF Available

https://doi.org/10.1186/1742-4690-3-83

Copy DOI

Export

Save

Cite

Abstract
Highlights/Summary
Full-Text PDF
Similar Papers

Abstract

Listen

BackgroundThe HIV Rev protein is known to facilitate export of incompletely spliced and unspliced viral transcripts to the cytoplasm, a necessary step in virus life cycle. The Rev-mediated nucleo-cytoplasmic transport of nascent viral transcripts, dependents on interaction of Rev with the RRE RNA structural element present in the target RNAs. The C-terminal variant of dsRNA-binding nuclear protein 90 (NF90ctv) has been shown to markedly attenuate viral replication in stably transduced HIV-1 target cell line. Here we examined a mechanism of interference of viral life cycle involving Rev-NF90ctv interaction.ResultsSince Rev:RRE complex formations depend on protein:RNA and protein:protein interactions, we investigated whether the expression of NF90ctv might interfere with Rev-mediated export of RRE-containing transcripts. When HeLa cells expressed both NF90ctv and Rev protein, we observed that NF90ctv inhibited the Rev-mediated RNA transport. In particular, three regions of NF90ctv protein are involved in blocking Rev function. Moreover, interaction of NF90ctv with the RRE RNA resulted in the expression of a reporter protein coding sequences linked to the RRE structure. Moreover, Rev influenced the subcellular localization of NF90ctv, and this process is leptomycin B sensitive.ConclusionThe dsRNA binding protein, NF90ctv competes with HIV Rev function at two levels, by competitive protein:protein interaction involving Rev binding to specific domains of NF90ctv, as well as by its binding to the RRE-RNA structure. Our results are consistent with a model of Rev-mediated HIV-1 RNA export that envisions Rev-multimerization, a process interrupted by NF90ctv.

Highlights

The HIV Rev protein is known to facilitate export of incompletely spliced and unspliced viral transcripts to the cytoplasm, a necessary step in virus life cycle
The results show that either Rev protein (Rev/monomeric red fluorescent protein (mRFP)) or NF90ctv (NF90/mRFP) influence Gag-Rev response element (RRE)-GFP expression, suggesting that NF90ctv may influence the nucleocytoplasmic translocation of RRE containing transcripts, analogous to Rev function
Since the nuclear export signal (NES) motif located in the Nterminal region of NF90ctv is similar to the hydrophobic Leu-rich region present in proteins [24] known to recruit the exportin Crm1 [3], we suggest that export of NF90ctv to the cytoplasm may be Crm1-dependent (Fig. 7b)

Summary

Introduction

The HIV Rev protein is known to facilitate export of incompletely spliced and unspliced viral transcripts to the cytoplasm, a necessary step in virus life cycle. Regulation of HIV-1 gene expression is controlled mainly by the two virus encoded proteins, Tat responsible for processive transcription elongation, and Rev which regulates transport of unspliced and incompletely spliced viral transcripts from the nucleus to the cytoplasm. These two regulatory proteins function by binding to structured RNA domains present in the viral transcripts, the trans-activation responsive RNA (TAR) and the Rev response element (RRE) respectively

Methods

Results

Conclusion