Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of the Chinese Academy of Sciences, Beijing 100049, China; College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China.
Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Virus Res. 2014 Feb 13;180:1-11. doi: 10.1016/j.virusres.2013.11.020. Epub 2013 Dec 4.
Nuclear proteins can be triggered to be redistributed to the cytoplasm to assist with EV71 virus replication. This process is frequently involved in cellular signal transduction upon virus infection. In this study, we have demonstrated that a new nuclear protein, 68-kDa Src-associated in mitosis protein (Sam68), was translocated to the cytoplasm and was co-localized with EV71 during virus infection. Confocal microscopy and subcellular fractionation assay confirmed that virus 3C protease triggered the redistribution of Sam68 to the cytoplasm. Knockdown of Sam68 expression using ShRNA significantly inhibited virus replication, suggesting that Sam68 may be a host factor involved in EV71 life cycle. In addition, EV71-induced Akt phosphorylation involved a PI3K-dependent mechanism. Sam68 is known to be an upstream regulator of PI3K and our immunoprecipitation studies confirmed that Sam68 interacted directly with the p85 regulatory subunit of PI3K and mediated PI3K/Akt activation during EV71 infection. On the contrary, silencing of Sam68 dramatically abrogated Akt phosphorylation. These data, plus the fact that Sam68 is known to be a signaling adaptor protein, indicated that Sam68 is a signal molecule with a functional role in the PI3K/Akt signal pathway during EV71 infection.
核蛋白可被触发重新分布到细胞质中，以协助 EV71 病毒复制。这一过程在病毒感染时经常涉及细胞信号转导。在本研究中，我们已经证明，一种新的核蛋白，有丝分裂中与Src 相关的 68kDa 蛋白（Sam68），在病毒感染时被转位到细胞质中，并与 EV71 共定位。共聚焦显微镜和亚细胞分级分离实验证实，病毒 3C 蛋白酶触发了 Sam68 向细胞质的重新分布。使用 ShRNA 敲低 Sam68 的表达显著抑制了病毒的复制，这表明 Sam68 可能是参与 EV71 生命周期的宿主因子。此外，EV71 诱导的 Akt 磷酸化涉及 PI3K 依赖性机制。Sam68 是 PI3K 的上游调节剂，我们的免疫沉淀研究证实 Sam68 直接与 PI3K 的 p85 调节亚基相互作用，并在 EV71 感染过程中介导 PI3K/Akt 的激活。相反，沉默 Sam68 显著阻断了 Akt 的磷酸化。这些数据，加上 Sam68 是已知的信号接头蛋白这一事实，表明 Sam68 是 EV71 感染过程中 PI3K/Akt 信号通路中的一种信号分子，具有功能作用。
