Antagonism of tetherin restriction of HIV-1 release by Vpu involves binding and sequestration of the restriction factor in a perinuclear compartment.
Antagonism of tetherin restriction of HIV-1 release by Vpu involves binding and sequestration of the restriction factor in a perinuclear compartment.
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DOI：
10.1371/journal.ppat.1000856
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发表时间：
2010-04-08
期刊：
影响因子：
6.7
通讯作者：
Cohen EA
中科院分区：
文献类型：
--
作者：
Dubé M;Roy BB;Guiot-Guillain P;Binette J;Mercier J;Chiasson A;Cohen EA
Vpu辅助蛋白通过抵消Tetherin/BST-2（一种干扰素调节的限制因子）促进HIV-1释放，Tetherin/BST-2将病毒粒子保留在细胞表面。最近的研究表明，Vpu可能通过β-TrCP依赖的蛋白酶体和/或内溶酶体降解Tetherin来下调Tetherin的细胞表面表达并拮抗这种限制。然而，在所有这些研究中，拴系蛋白降解并不能完全解释Vpu抗拴系蛋白活性。在这里，我们表明，Vpu可以促进HIV-1的释放，而不会影响Tetherin的稳态水平或营业额，这表明Tetherin降解可能不是必要的和/或足够的Vpu抗Tetherin活性。尽管Vpu没有增强Tetherin从质膜（PM）的内化，但它确实显著减缓了蛋白质向细胞表面的整体运输。因此，Vpu表达引起细胞表面Tetherin的特异性去除和Tetherin的残留池在与TGN标记物TGN 46和Vpu本身共染色的核周区室中的重新定位。在不能募集β-TrCP的Vpu突变体中也观察到了Tetherin的这种重新定位，表明这种活性的发生独立于β-TrCP介导的运输和/或降解过程。我们还表明，Vpu与Tetherin共免疫沉淀，这种相互作用涉及两种蛋白质的跨膜结构域。重要的是，发现这种关联对于减少细胞表面Tetherin表达，重新定位TGN中的限制因子和促进HIV-1释放至关重要。总的来说，我们的研究结果表明，关联的Vpu Tetherin影响向外贩运和/或回收的限制因子从TGN，并因此促进其隔离远离生产性HIV-1大会发生的PM。这种导致TGN捕获的拮抗机制可能会被β-TrCP依赖性降解增强，这强调了需要补充和协同策略来有效抵消人Tetherin的强大限制作用。限制因子是干扰病毒增殖和传播的细胞蛋白质，因此是天然免疫的重要组成部分。Tetherin（也称为BST-2）是一种最近发现的限制性因子，可以将病毒捕获在细胞表面，阻止它们的释放，从而感染其他细胞。然而，病毒已经发展出了抵消这种限制因素的方法。病毒蛋白U（Vpu）是由艾滋病的病原体HIV-1编码的辅助蛋白。Vpu拮抗Tetherin，从而促进HIV-1颗粒的释放。最近的一系列报道提出，Vpu将诱导该限制因子的降解，以克服其抗病毒活性。在这里，我们报告说，Vpu能够增强HIV-1的释放，在没有Tetherin降解。相反，我们发现Vpu与Tetherin相互作用并干扰限制因子向细胞表面的运输。这将导致Tetherin在称为trans-Golgi网络的细胞内细胞器中重新定位，导致细胞表面的Tetherin水平不足以捕获子代病毒。这种导致TGN捕获的拮抗机制可以通过诱导降解来增强，以有效抵消人Tetherin的强大限制作用。对这一机制的进一步研究将提高我们对宿主抗病毒防御机制的理解，并为开发新型抗HIV药物提供新的靶点。
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. Restriction factors are cellular proteins that interfere with the multiplication and transmission of viruses and are therefore important components of natural immunity. Tetherin (also known as BST-2) is a recently identified restriction factor that traps viruses at the cell-surface, preventing their release and thus infection of other cells. Viruses have, however, developed means to counteract this restriction factor. Viral protein U (Vpu) is an accessory protein encoded by HIV-1, the causative agent of AIDS. Vpu antagonizes Tetherin and consequently promotes the release of HIV-1 particles. A series of recent reports proposed that Vpu would induce the degradation of this restriction factor in order to overcome its anti-viral activity. Here, we report that Vpu is able to enhance HIV-1 release in absence of Tetherin degradation. Instead, we found that Vpu interacts with Tetherin and interferes with the transport of the restriction factor towards the cell-surface. This would lead to re-localization of Tetherin in an intracellular organelle called the trans-Golgi network, resulting in insufficient levels of Tetherin at the cell-surface to trap progeny viruses. This mechanism of antagonism that results in TGN trapping could be augmented by the induction of degradation to effectively counteract the powerful restrictive effects of human Tetherin. Further characterization of this mechanism will improve our understanding of host antiviral defenses as well as provide new targets for the development of novel anti-HIV drugs.
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DOI：
10.1073/pnas.0907075106
发表时间：
2009-12-08
影响因子：
11.1
作者：
Gupta, Ravindra K.;Mlcochova, Petra;Towers, Greg J.
通讯作者：
Towers, Greg J.
影响因子：
5.4
作者：
Mansouri, Mandana;Viswanathan, Kasinath;Frueh, Klaus
通讯作者：
Frueh, Klaus
影响因子：
30.3
作者：
Goffinet, Christine;Allespach, Ina;Keppler, Oliver T.
通讯作者：
Keppler, Oliver T.
影响因子：
5.4
作者：
Grigg，ME;McMahon，CW;Pullen，AM
通讯作者：
Pullen，AM
影响因子：
6.7
作者：
McNatt, Matthew W.;Zang, Trinity;Hatziioannou, Theodora;Bartlett, Mackenzie;Ben Fofana, Ismael;Johnson, Welkin E.;Neil, Stuart J. D.;Bieniasz, Paul D.
通讯作者：
Bieniasz, Paul D.