Unraveling the molecular link between HIVAIDS and cancer

我们的无偏蛋白质组质谱和随后的生化分析表明，Plk4通过其C端隐蔽的Polo盒与细胞支架蛋白VprBP的C端酸性结构域(1401-1507)结合。值得注意的是，HIV-1 VPR与VprBP的WD40结构域(1003-1400)结合，大大增强了VprBP-Plk4的相互作用，并诱导了VPR-VprBP-Plk4复合体的形成。这三种蛋白质都共定位于中心体，三元复合体的形成似乎增强了Plk4介导的中心粒复制。与这些发现一致的是，VprBP通过稳定其中心粒相关状态而不是像在VPX-VprBP-SAMHD1复合体和其他细胞靶标中观察到的那样诱导其蛋白酶体降解来促进Plk4的功能。这些数据表明，当细胞感染HIV-1时，vpr可能通过在生理条件下形成vpr-vprBP-plk4复合体而改变Plk4的S功能，并诱导Plk4依赖的中心粒过度复制，这是一种导致非整倍体和癌症的细胞事件。一个结构上相关的HIV-2 VPX不能与VprBP和Plk4相互作用，表明HIV-1 VPR诱导的事件的特异性。基于这些观察，我们推测HIV-1Vpr可以直接改变基因组的稳定性，并通过劫持细胞内的Plk4-VprBP复合体而促进癌症的发生。计划进行更多的研究，以确定VPR-VprBP-Plk4三元复合体在生理相关条件下的作用，使用动物模型中对HIV-1敏感的细胞和组织。这项研究可能揭示艾滋病毒/艾滋病与其共病癌症的病因学直接联系的机制。此外，它可能为理解HIV-1携带者癌症风险增加提供一个新的范式。调查艾滋病毒引起的合并症是美国国立卫生研究院指定的四个艾滋病毒/艾滋病研究重点之一。这项研究旨在直接解决与HIV-1相关的癌症并存问题。我们在研究HIV蛋白如何与细胞靶标相互作用和改变细胞生理方面获得了丰富的经验，使用各种生化和基于结构的分析。此外，我们确定VPR-VprBP-Plk4复合体的四元结构的努力一直进展顺利。一旦确定了四级结构，我们将有兴趣设计能够破坏复合体的抑制剂，从而帮助防止艾滋病毒-1诱导的中心体异常及其相关的人类疾病，如癌症。我们从各种培养细胞中获得的数据表明，通过删除VPR的C末端尾巴或VprBP的酸性区域来破坏VPR-VprBP-Plk4复合体，足以消除VPR依赖的中心体扩增和包括原始T细胞在内的多个CD4+细胞的非整倍体。鉴于非整倍体与癌症的密切联系，这些发现表明，HIV-1诱导的VPR-VprBP-Plk4复合体可以通过劫持Plk4介导的中心粒复制的宿主机制，直接促进HIV-1敏感的T细胞或其他血液VPR可转导细胞的肿瘤发生。鉴于这一发现，即使在联合抗逆转录病毒治疗期间，发生非霍奇金淋巴瘤的风险仍然很高，这项工作可能为研究导致HIV-1相关癌症的潜在机制提供新的方向。

Our unbiased proteomic mass spectrometry and subsequent biochemical analyses showed that Plk4 binds to the C-terminal acidic domain (1401-1507) of a cellular scaffold protein, VprBP, via its C-terminal cryptic polo-box. Strikingly, HIV-1 Vpr, which binds to the WD40 domain (1003-1400) of VprBP, greatly enhanced the VprBP-Plk4 interaction and induced the formation of the Vpr-VprBP-Plk4 complex. All three proteins colocalized to centrosomes, and the ternary complex formation appeared to augment Plk4-mediated centriole duplication. Consistent with these findings, VprBP promoted Plk4 function by stabilizing its centriole-associated state rather than inducing its proteasomal degradation, as was observed for the Vpx-VprBP-SAMHD1 complex and other cellular targets. These data suggest that when cells are infected with HIV-1, Vpr may alter Plk4's function by forming the Vpr-VprBP-Plk4 complex under physiological conditions and induce Plk4-dependent centriole overduplication, a cellular event causing aneuploidy and cancer. A structurally related HIV-2 Vpx failed to interact with VprBP and Plk4, indicating the specificity of HIV-1 Vpr-induced events. Based on these observations, we postulate that HIV-1 Vpr can directly alter genomic stability and facilitate carcinogenesis by hijacking the cellular Plk4-VprBP complex. Additional studies are planned to determine the role of the ternary Vpr-VprBP-Plk4 complex under physiologically relevant conditions using HIV-1-susceptible cells and tissues in animal models. This research could shed light on the mechanism that could directly link HIV/AIDS to the etiology of its comorbid cancers. Furthermore, it may offer a new paradigm in understanding the increased cancer risk in people with HIV-1. Investigating HIV-induced comorbidities is one of the four designated NIH HIV/AIDS research priorities. This research is designed to directly address HIV-1-associated cancer comorbidities. We have gained an enriched experience in studying how HIV proteins interact with cellular targets and alter cell physiology using various biochemical and structure-based analyses. Furthermore, our efforts to determine the quaternary structure of the Vpr-VprBP-Plk4 complex have been moving along well. Once the quaternary structure is determined, we will be interested in designing inhibitors that could disrupt the complex and thus help prevent HIV-1-induced centrosomal abnormalities and their associated human disorders, such as cancer. The data that we obtained from various cultured cells revealed that disrupting the Vpr-VprBP-Plk4 complex by either deleting the Vpr's C-terminal tail or the VprBP's acidic region was sufficient to abolish Vpr-dependent centrosome amplification and aneuploidy in multiple CD4+ cells, including primary T cells. Given the tight association of aneuploidy and cancer, these findings suggest that the HIV-1-induced Vpr-VprBP-Plk4 complex can directly promote oncogenesis in HIV-1-susceptible T cells or other blood Vpr-transducible cells by hijacking the host machinery for Plk4-mediated centriole duplication. In light of the finding that the risk of developing NHL remains high even during the combination antiretroviral therapy, this work may offer a new direction for investigating underlying mechanisms that give rise to HIV-1-associated cancers.