Human immunodeficiency virus type 1 Vpr-binding protein VprBP, a WD40 protein associated with the DDB1-CUL4 E3 ubiquitin ligase, is essential for DNA replication and embryonic development
Human immunodeficiency virus type 1 Vpr-binding protein VprBP, a WD40 protein associated with the DDB1-CUL4 E3 ubiquitin ligase, is essential for DNA replication and embryonic development
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DOI：
10.1128/mcb.00232-08
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发表时间：
2008-09-01
影响因子：
5.3
通讯作者：
Xiong, Yue
中科院分区：
文献类型：
--
作者：
McCall, Chad M.;de Marval, Paula L. Miliani;Xiong, Yue
受损的DNA结合蛋白1，DDB 1，桥接估计90个或更多的WD 40重复（DDB 1结合WD 40，或DWD蛋白）的CUL 4-ROC 1催化核心，构成一个潜在的大量的E3连接酶复合物。在这些DWD蛋白中，有人类免疫缺陷病毒1型（HIV-1）Vpr结合蛋白VprBP，其细胞功能尚未被表征，但最近发现介导Vpr诱导的G（2）细胞周期停滞。我们在这里证明，VprBP通过其WD 40结构域与DDB 1化学计量结合，并通过DDB 1与CUL 4A、COP 9/信号体亚基和DDA 1结合。VprBP的稳态水平在间期期间保持恒定，并在有丝分裂期间降低。VprBP以DDB 1非依赖性和细胞周期依赖性的方式与染色质结合，在有丝分裂和G（1）细胞中从早期S到G（2）增加，然后降低到不可检测的水平。沉默VprBP降低了DNA复制的速率，阻止细胞通过S期，并抑制增殖。小鼠中的VprBP消融导致早期胚胎致死。小鼠胚胎成纤维细胞中VprBP基因的条件性缺失导致通过S期的严重缺陷进展和随后的凋亡。我们的研究确定了VprBP在S期进展中以前未知的功能，并表明HIV-1 Vpr可能会转移正在进行的染色体复制活动以促进病毒复制。
Damaged DNA binding protein 1, DDB1, bridges an estimated 90 or more WD40 repeats (DDB1-binding WD40, or DWD proteins) to the CUL4-ROC1 catalytic core to constitute a potentially large number of E3 ligase complexes. Among these DWD proteins is the human immunodeficiency virus type 1 (HIV-1) Vpr-binding protein VprBP, whose cellular function has yet to be characterized but has recently been found to mediate Vpr-induced G(2) cell cycle arrest. We demonstrate here that VprBP binds stoichiometrically with DDB1 through its WD40 domain and through DDB1 to CUL4A, subunits of the COP9/signalsome, and DDA1. The steady-state level of VprBP remains constant during interphase and decreases during mitosis. VprBP binds to chromatin in a DDB1-independent and cell cycle-dependent manner, increasing from early S through G(2) before decreasing to undetectable levels in mitotic and G(1) cells. Silencing VprBP reduced the rate of DNA replication, blocked cells from progressing through the S phase, and inhibited proliferation. VprBP ablation in mice results in early embryonic lethality. Conditional deletion of the VprBP gene in mouse embryonic fibroblasts results in severely defective progression through S phase and subsequent apoptosis. Our studies identify a previously unknown function of VprBP in S-phase progression and suggest the possibility that HIV-1 Vpr may divert an ongoing chromosomal replication activity to facilitate viral replication.