Valosin-containing protein (VCP) plays roles in various cellular activities. Recently, Enterovirus A71 (EVA71) infection was found to hijack the VCP protein. However, the mechanism by which VCP participates in the EVA71 life cycle remains unclear. Using chemical inhibitor, RNA interference and dominant negative mutant, we confirmed that the VCP and its ATPase activity were critical for EVA71 infection. To identify the factors downstream of VCP in enterovirus infection, 31 known VCP-cofactors were screened in the siRNA knockdown experiments. The results showed that UFD1 (ubiquitin recognition factor in ER associated degradation 1), but not NPL4 (NPL4 homolog, ubiquitin recognition factor), played critical roles in infections by EVA71. UFD1 knockdown suppressed the activity of EVA71 pseudovirus (causing single round infection) while it did not affect the viral replication in replicon RNA transfection assays. In addition, knockdown of VCP and UFD1 reduced viral infections by multiple human Enterovirus A serotypes. Mechanistically, we found that knockdown of UFD1 significantly decreased the binding and the subsequent entry of EVA71 to host cells through modulating the levels of nucleolin protein, a coreceptor of EVA71. Together, these data reveal novel roles of VCP and its cofactor UFD1 in the virus entry by EVA71.

中文翻译：

---

VCP/UFD1/核仁素参与肠道病毒 A 种的病毒进入。


含 Valosin 的蛋白 (VCP) 在多种细胞活动中发挥作用。最近，发现肠道病毒A71（EVA71）感染可以劫持VCP蛋白。然而，VCP参与EVA71生命周期的机制仍不清楚。使用化学抑制剂、RNA干扰和显性失活突变体，我们证实VCP及其ATP酶活性对于EVA71感染至关重要。为了确定肠道病毒感染中 VCP 下游的因子，在 siRNA 敲低实验中筛选了 31 种已知的 VCP 辅因子。结果表明，UFD1（ER相关降解中的泛素识别因子1），而不是NPL4（NPL4同源物，泛素识别因子），在EVA71感染中发挥关键作用。 UFD1敲低抑制了EVA71假病毒的活性（导致单轮感染），同时不影响复制子RNA转染测定中的病毒复制。此外，敲除VCP和UFD1可减少多种人类肠道病毒A血清型的病毒感染。从机制上讲，我们发现UFD1的敲低通过调节核仁蛋白（EVA71的共同受体）的水平显着减少了EVA71与宿主细胞的结合和随后的进入。总之，这些数据揭示了 VCP 及其辅因子 UFD1 在 EVA71 病毒进入中的新作用。