Antagonism of Tetherin Restriction of HIV-1 Release by Vpu Involves Binding and Sequestration of the Restriction Factor in a Perinuclear Compartment

PLoS Pathogens

Mathieu Dubé¹  Julie Binette¹  Bibhuti Bhusan Roy¹  Éric A. Cohen¹  Pierre Guiot-Guillain¹  Johanne Mercier¹  Antoine Chiasson¹ 

[1] Laboratory of Human Retrovirology, Institut de recherches cliniques de Montréal (IRCM), Montreal, Quebec, Canada

关键词: HIV-1;    HeLa cells;    293T cells;    Cell membranes;    Plasmid construction;    Endocytosis;    Membrane proteins;    Protein transport;   

DOI  :  10.1371/journal.ppat.1000856

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The Vpu accessory protein promotes HIV-1 release by counteracting Tetherin/BST-2, an interferon-regulated restriction factor, which retains virions at the cell-surface. Recent reports proposed β-TrCP-dependent proteasomal and/or endo-lysosomal degradation of Tetherin as potential mechanisms by which Vpu could down-regulate Tetherin cell-surface expression and antagonize this restriction. In all of these studies, Tetherin degradation did not, however, entirely account for Vpu anti-Tetherin activity. Here, we show that Vpu can promote HIV-1 release without detectably affecting Tetherin steady-state levels or turnover, suggesting that Tetherin degradation may not be necessary and/or sufficient for Vpu anti-Tetherin activity. Even though Vpu did not enhance Tetherin internalization from the plasma membrane (PM), it did significantly slow-down the overall transport of the protein towards the cell-surface. Accordingly, Vpu expression caused a specific removal of cell-surface Tetherin and a re-localization of the residual pool of Tetherin in a perinuclear compartment that co-stained with the TGN marker TGN46 and Vpu itself. This re-localization of Tetherin was also observed with a Vpu mutant unable to recruit β-TrCP, suggesting that this activity is taking place independently from β-TrCP-mediated trafficking and/or degradation processes. We also show that Vpu co-immunoprecipitates with Tetherin and that this interaction involves the transmembrane domains of the two proteins. Importantly, this association was found to be critical for reducing cell-surface Tetherin expression, re-localizing the restriction factor in the TGN and promoting HIV-1 release. Overall, our results suggest that association of Vpu to Tetherin affects the outward trafficking and/or recycling of the restriction factor from the TGN and as a result promotes its sequestration away from the PM where productive HIV-1 assembly takes place. This mechanism of antagonism that results in TGN trapping is likely to be augmented by β-TrCP-dependent degradation, underlining the need for complementary and perhaps synergistic strategies to effectively counteract the powerful restrictive effects of human Tetherin.

【 授权许可】

CC BY