DEAD/H BOX 3 (DDX3) helicase binds the RIG-I adaptor IPS-1 to up-regulate IFN-β-inducing potential
DEAD/H BOX 3 (DDX3) helicase binds the RIG-I adaptor IPS-1 to up-regulate IFN-β-inducing potential
复制标题
DOI：
10.1002/eji.200940203
复制
发表时间：
2010-04-01
影响因子：
5.4
通讯作者：
Seya, Tsukasa
中科院分区：
文献类型：
--
作者：
Oshiumi, Hiroyuki;Sakai, Keisuke;Seya, Tsukasa
视黄酸诱导基因-I（RIG-I）样受体（RLR）是DEAD盒解旋酶的成员，并识别细胞质中的病毒RNA，导致通过衔接子IFN-β启动子刺激因子-I（IPS-1）（也称为Cardif，线粒体抗病毒信号蛋白或病毒诱导信号衔接子）诱导IFN-β。由于未感染的细胞通常含有微量的RIG-I，其他RNA结合蛋白可能在对感染的初始反应期间参与将病毒RNA组装到IPS-1途径中。利用酵母双杂交技术寻找与人IPS-1偶联的蛋白质，并鉴定出另一个DEAD（Asp-Glu-Ala-Asp）盒解旋酶DDX 3（DEAD/HBOX 3）。DDX 3可以结合病毒RNA，将其加入IPS-1复合物中。与RIG-I不同，DDX 3在细胞中组成型表达，并且DDX 3的一些部分与IPS-1共定位在线粒体周围。622-662 a.a DDX 3 C-末端区域（DDX 3-C）直接结合IPS-1 CARD样结构域，并且整个DDX 3蛋白也与RLR相关。通过报告基因分析，DDX 3帮助IPS-1上调IFN-β启动子激活，并且通过siRNA敲低DDX 3导致IFN-β诱导减少。该活性在DDX 3-C片段上是保守的。DDX 3仅略微增强由转染的TANK结合激酶1（TBK 1）或I-κ-B激酶-κ（IKK κ）诱导的IFN-β启动子活化。DDX 3的强制表达增强了病毒介导的IFN-β诱导和宿主细胞对病毒感染的保护。因此，DDX 3是抗病毒IPS-1增强剂。
Retinoic acid-inducible gene-I (RIG-I)-like receptors (RLR) are members of the DEAD box helicases, and recognize viral RNA in the cytoplasm, leading to IFN-beta induction through the adaptor IFN-beta promoter stimulator-1 (IPS-1) (also known as Cardif, mitochondrial antiviral signaling protein or virus-induced signaling adaptor). Since uninfected cells usually harbor a trace of RIG-I, other RNA-binding proteins may participate in assembling viral RNA into the IPS-1 pathway during the initial response to infection. We searched for proteins coupling with human IPS-1 by yeast two-hybrid and identified another DEAD (Asp-Glu-Ala-Asp) box helicase, DDX3 (DEAD/H BOX 3). DDX3 can bind viral RNA to join it in the IPS-1 complex. Unlike RIG-I, DDX3 was constitutively expressed in cells, and some fraction of DDX3 is colocalized with IPS-1 around mitochondria. The 622-662 a.a DDX3 C-terminal region (DDX3-C) directly bound to the IPS-1 CARD-like domain, and the whole DDX3 protein also associated with RLR. By reporter assay, DDX3 helped IPS-1 up-regulate IFN-beta promoter activation and knockdown of DDX3 by siRNA resulted in reduced IFN-beta induction. This activity was conserved on the DDX3-C fragment. DDX3 only marginally enhanced IFN-beta promoter activation induced by transfected TANK-binding kinase 1 (TBK1) or I-kappa-B kinase-epsilon (IKK epsilon). Forced expression of DDX3 augmented virus-mediated IFN-beta induction and host cell protection against virus infection. Hence, DDX3 is an antiviral IPS-1 enhancer.