Inhibition of CUL4A Neddylation Causes a Reversible Block to SAMHD1-Mediated Restriction of HIV-1
Inhibition of CUL4A Neddylation Causes a Reversible Block to SAMHD1-Mediated Restriction of HIV-1
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DOI：
10.1128/jvi.02002-13
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发表时间：
2013-11-01
影响因子：
5.4
通讯作者：
Landau, Nathaniel R.
中科院分区：
文献类型：
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作者：
Hofmann, Henning;Norton, Thomas D.;Landau, Nathaniel R.
脱氧核苷三磷酸水解酶SAMHD 1限制骨髓细胞中的逆转录病毒复制。人类免疫缺陷病毒2型（HIV-2）和来自恒河猴的猿猴免疫缺陷病毒（SIVmac）编码Vpx，Vpx是一种病毒体包装的辅助蛋白，通过诱导SAMHD 1降解来抵消SAMHD 1。SAMHD 1被认为是通过消耗细胞内脱氧核苷三磷酸池来起作用的，但也有报道称其具有外切核酸酶活性，可以使其降解病毒基因组RNA或病毒逆转录DNA。为了诱导SAMHD 1的降解，Vpx选择了基于cullin 4a的E3泛素连接酶CRL 4。E3泛素连接酶通过泛素样蛋白Nedd 8与cullin亚基的共价连接来调节。Neddylation可通过MLN 4924（一种抑制nedd 8激活酶的药物）预防。我们报告称，MLN 4924可抑制CRL 4的neddylation，阻断Vpx诱导的SAMHD 1降解并维持限制。感染后数小时取出药物，阻滞解除。同样，Vpx含有病毒样颗粒和脱氧核苷添加到细胞超过24小时感染后释放SAMHD 1介导的块。总之，这些发现支持脱氧核苷三磷酸池耗尽作为SAMHD 1限制的主要机制，并反对不可逆的溶核机制。
The deoxynucleoside triphosphohydrolase SAMHD1 restricts retroviral replication in myeloid cells. Human immunodeficiency virus type 2 (HIV-2) and a simian immunodeficiency virus from rhesus macaques (SIVmac) encode Vpx, a virion-packaged accessory protein that counteracts SAMHD1 by inducing its degradation. SAMHD1 is thought to work by depleting the pool of intracellular deoxynucleoside triphosphates but has also been reported to have exonuclease activity that could allow it to degrade the viral genomic RNA or viral reverse-transcribed DNA. To induce the degradation of SAMHD1, Vpx co-opts the cullin4a-based E3 ubiquitin ligase, CRL4. E3 ubiquitin ligases are regulated by the covalent attachment of the ubiquitin-like protein Nedd8 to the cullin subunit. Neddylation can be prevented by MLN4924, a drug that inhibits the nedd8-activating enzyme. We report that MLN4924 inhibits the neddylation of CRL4, blocking Vpx-induced degradation of SAMHD1 and maintaining the restriction. Removal of the drug several hours postinfection released the block. Similarly, Vpx-containing virus-like particles and deoxynucleosides added to the cells more than 24 h postinfection released the SAMHD1-mediated block. Taken together, these findings support deoxynucleoside triphosphate pool depletion as the primary mechanism of SAMHD1 restriction and argue against a nucleolytic mechanism, which would not be reversible.