Kubota Toru, Yokosawa Noriko, Yokota Shin-ichi, Fujii Nobuhiro
Department of Microbiology, School of Medicine, Sapporo Medical University, South 1 West 17, Chou-ku, Sapporo 060-8556, Hokkaido, Japan.
J Virol. 2002 Dec;76(24):12676-82. doi: 10.1128/jvi.76.24.12676-12682.2002.
It has been reported that mumps virus protein V or the C-terminal Cys-rich region of protein V (Vsp) is associated with blocking of the interferon (IFN) signal transduction pathway through a decrease in STAT-1 production. The intracellular target of the V protein was investigated by using a two-hybrid screening system with Vsp as bait. Full-length V protein and Vsp were able to bind to RACK1, and the interaction did not require two WD domains, WD1 and WD2, in RACK1. A significant interaction between V protein and RACK1 was also demonstrated in cells persistently infected with mumps virus (FLMT cells), and the formation of the complex was not affected by treatment with IFN. On the other hand, in uninfected cells, STAT-1 was associated with the long form of the beta subunit of the alpha IFN receptor, and this association was mediated by the function of RACK1 as an adaptor protein. Immunoprecipitation and glutathione S-transferase pull-down experiments revealed that the association of RACK1 or mumps virus V protein with the IFN receptor was undetectable in mumps virus-infected cells. Furthermore, RACK1 interacted with mumps virus V protein with a higher affinity than STAT-1 did. Therefore, it is suggested that mumps virus V protein has the ability to interact strongly with RACK1 and consequently to bring about the disruption of the complex formed from STAT-1, RACK1, and the IFN receptor.
据报道，腮腺炎病毒蛋白V或蛋白V的C末端富含半胱氨酸区域（Vsp）与通过降低STAT-1产生来阻断干扰素（IFN）信号转导途径有关。通过使用以Vsp为诱饵的双杂交筛选系统研究了V蛋白的细胞内靶标。全长V蛋白和Vsp能够与RACK1结合，并且这种相互作用不需要RACK1中的两个WD结构域WD1和WD2。在持续感染腮腺炎病毒的细胞（FLMT细胞）中也证明了V蛋白与RACK1之间存在显著的相互作用，并且复合物的形成不受IFN处理的影响。另一方面，在未感染的细胞中，STAT-1与α干扰素受体β亚基的长形式相关，并且这种关联是由RACK1作为衔接蛋白的功能介导的。免疫沉淀和谷胱甘肽S-转移酶下拉实验表明，在腮腺炎病毒感染的细胞中未检测到RACK1或腮腺炎病毒V蛋白与IFN受体的关联。此外，RACK1与腮腺炎病毒V蛋白的相互作用亲和力高于STAT-1。因此，提示腮腺炎病毒V蛋白具有与RACK1强烈相互作用的能力，从而导致由STAT-1、RACK1和IFN受体形成的复合物的破坏。
