Bolton Diane L, Barnitz Robert A, Sakai Keiko, Lenardo Michael J
Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD 20892, USA.
Biol Direct. 2008 Apr 29;3:17. doi: 10.1186/1745-6150-3-17.
Despite continuing advances in our understanding of AIDS pathogenesis, the mechanism of CD4+ T cell depletion in HIV-1-infected individuals remains unclear. The HIV-1 Vpr accessory protein causes cell death, likely through a mechanism related to its ability to arrest cells in the G2,M phase. Recent evidence implicated the scaffold protein, 14-3-3, in Vpr cell cycle blockade.
We found that in human T cells, 14-3-3 plays an active role in mediating Vpr-induced cell cycle arrest and reveal a dramatic increase in the amount of Cdk1, Cdc25C, and CyclinB1 bound to 14-3-3 theta during Vprv-induced G2,M arrest. By contrast, a cell-cycle-arrest-dead Vpr mutant failed to augment 14-3-3 theta association with Cdk1 and CyclinB1. Moreover, G2,M arrest caused by HIV-1 infection strongly correlated with a disruption in 14-3-3 theta binding to centrosomal proteins, Plk1 and centrin. Finally, Vpr caused elevated levels of CyclinB1, Plk1, and Cdk1 in a complex with the nuclear transport and spindle assembly protein, importin beta.
Thus, our data reveal a new facet of Vpr-induced cell cycle arrest involving previously unrecognized abnormal rearrangements of multiprotein assemblies containing key cell cycle regulatory proteins.
尽管我们对艾滋病发病机制的理解不断取得进展，但HIV-1感染个体中CD4+T细胞耗竭的机制仍不清楚。HIV-1辅助蛋白Vpr可导致细胞死亡，可能是通过一种与其将细胞阻滞在G2/M期的能力相关的机制。最近的证据表明，支架蛋白14-3-3参与了Vpr诱导的细胞周期阻滞。
我们发现，在人T细胞中，14-3-3在介导Vpr诱导的细胞周期阻滞中发挥积极作用，并发现Vpr诱导G2/M期阻滞期间，与14-3-3θ结合的细胞周期蛋白依赖性激酶1（Cdk1）、细胞分裂周期蛋白25C（Cdc25C）和细胞周期蛋白B1（CyclinB1）的量显著增加。相比之下，一个细胞周期阻滞失活的Vpr突变体未能增强14-3-3θ与Cdk1和CyclinB1的结合。此外，HIV-1感染引起的G2/M期阻滞与14-3-3θ与中心体蛋白Plk1和中心粒蛋白的结合破坏密切相关。最后，Vpr导致与核转运和纺锤体组装蛋白输入蛋白β形成复合物的CyclinB1、Plk1和Cdk1水平升高。
因此，我们的数据揭示了Vpr诱导的细胞周期阻滞的一个新方面，涉及以前未被认识的含有关键细胞周期调节蛋白的多蛋白组装体的异常重排。
