Cyclin K Inhibits HIV-1 Gene Expression and Replication by Interfering with Cyclin-dependent Kinase 9 (CDK9)-Cyclin T1 Interaction in Nef-dependent Manner
Cyclin K Inhibits HIV-1 Gene Expression and Replication by Interfering with Cyclin-dependent Kinase 9 (CDK9)-Cyclin T1 Interaction in Nef-dependent Manner
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DOI：
10.1074/jbc.m110.201194
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发表时间：
2011-07-01
影响因子：
4.8
通讯作者：
Mitra, Debashis
中科院分区：
文献类型：
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作者：
Khan, Sohrab Zafar;Mitra, Debashis
人类免疫缺陷病毒-1（HIV-1）利用许多宿主细胞因子成功存活和繁殖。病毒蛋白Nef通过与多种细胞蛋白相互作用在HIV-1发病机制中起重要作用。在目前的工作中，我们确定了细胞周期蛋白K（CycK）作为一种新的Nef相互作用蛋白，并为第一次，我们表明，CycK抑制HIV-1基因的表达和复制的Nef依赖的方式。包含细胞周期蛋白依赖性激酶9（CDK 9）和细胞周期蛋白T1的正延伸因子B复合物是病毒基因表达和复制所需的关键细胞复合物。在Nef存在下CycK的表达增强诱导CycK-CDK 9结合，这阻止了CDK 9-Cyclin T1复合物的形成和CDK 9的核转位，从而抑制HIV-1长末端重复序列驱动的基因表达。此外，在Nef缺失的病毒中没有观察到CycK的这种作用，表明Nef在这种现象中的重要性。最后，在HIV-1感染的细胞中CycK的沉默导致CDK 9易位到细胞核中的增加，从而导致病毒基因表达和复制的增加。这些数据还表明，内源性CycK可能作为一种抑制因子的HIV-1基因的表达和复制的T细胞。因此，我们的研究结果清楚地表明，CycK利用HIV-1 Nef蛋白取代CycT 1从阳性延伸因子B复合物，导致抑制HIV-1基因的表达和复制。
Human immunodeficiency virus-1 (HIV-1) exploits a number of host cellular factors for successful survival and propagation. The viral protein Nef plays an important role in HIV-1 pathogenesis by interacting with various cellular proteins. In the present work, we identified Cyclin K (CycK) as a novel Nef-interacting protein, and for the first time, we showed that CycK inhibits HIV-1 gene expression and replication in a Nef-dependent manner. The positive elongation factor b complex comprising cyclin-dependent kinase 9 (CDK9) and Cyclin T1 is a critical cellular complex required for viral gene expression and replication. Enhanced expression of CycK in the presence of Nef induced CycK-CDK9 binding, which prevented CDK9-Cyclin T1 complex formation and nuclear translocation of CDK9, resulting in inhibition of HIV-1 long terminal repeat-driven gene expression. Furthermore, this effect of CycK was not observed with Nef-deleted virus, indicating the importance of Nef in this phenomenon. Finally, silencing of CycK in HIV-1-infected cells resulted in increased translocation of CDK9 into the nucleus, leading to increased viral gene expression and replication. These data also suggest that endogenous CycK might act as an inhibitory factor for HIV-1 gene expression and replication in T-cells. Thus, our results clearly demonstrate that CycK utilizes HIV-1 Nef protein to displace CycT1 from the positive elongation factor b complex, resulting in inhibition of HIV-1 gene expression and replication.