The Cellular NMD Pathway Restricts Zika Virus Infection and Is Targeted by the Viral Capsid Protein.
The Cellular NMD Pathway Restricts Zika Virus Infection and Is Targeted by the Viral Capsid Protein.
复制标题
细胞NMD途径限制了Zika病毒感染，并由病毒衣壳蛋白靶向。
作者：
Fontaine KA;Leon KE;Khalid MM;Tomar S;Jimenez-Morales D;Dunlap M;Kaye JA;Shah PS;Finkbeiner S;Krogan NJ;Ott M
寨卡病毒（ZIKV）是一种严重的全球健康威胁，因为感染与严重的神经系统并发症有关，包括小头畸形。使用人干细胞衍生的神经祖细胞模型系统，我们发现在ZIKV感染期间，称为无义介导的mRNA衰变（NMD）途径的关键细胞质量控制过程被破坏。重要的是，NMD途径的破坏是小头畸形和其他神经系统疾病的已知原因。我们进一步鉴定了ZIKV的衣壳蛋白与上移码蛋白1（UPF 1）（NMD的主调节因子）之间的相互作用，并显示ZIKV衣壳靶向UPF 1进行降解。总之，这些结果为ZIKV感染如何在发育中的大脑中引起神经病理学提供了新的机制。寨卡病毒（ZIKV）在子宫内感染神经祖细胞（NPC）与神经系统疾病（如小头畸形）相关，但缺乏对ZIKV诱导的发病机制的详细分子理解。在这里，我们表明，体外ZIKV感染人细胞，包括NPC，导致无义介导的mRNA衰变（NMD）途径的破坏。NMD是一种细胞mRNA监视机制，是小鼠正常大脑大小所必需的。使用亲和纯化-质谱法，我们鉴定了与病毒衣壳蛋白结合的多种细胞NMD因子，包括中央NMD调节因子上移码蛋白1（UPF 1）。在免疫共沉淀实验中，内源性UPF 1与ZIKV衣壳蛋白相互作用，并且衣壳表达转录后下调UPF 1蛋白水平，我们证实这一过程发生在ZIKV感染期间。细胞分级分离研究表明，ZIKV衣壳蛋白特异性靶向核UPF 1，通过蛋白酶体降解。通过RNAi进一步降低UPFl水平显著增强NPC培养物中的ZIKV感染，这与NMD限制胎儿脑中的ZIKV感染的模型一致。我们认为ZIKV通过衣壳蛋白已经进化出一种降低UPF 1水平和抑制NMD抗病毒活性的策略，这反过来有助于体内神经病理学。
Zika virus (ZIKV) is a significant global health threat, as infection has been linked to serious neurological complications, including microcephaly. Using a human stem cell-derived neural progenitor model system, we find that a critical cellular quality control process called the nonsense-mediated mRNA decay (NMD) pathway is disrupted during ZIKV infection. Importantly, disruption of the NMD pathway is a known cause of microcephaly and other neurological disorders. We further identify an interaction between the capsid protein of ZIKV and up-frameshift protein 1 (UPF1), the master regulator of NMD, and show that ZIKV capsid targets UPF1 for degradation. Together, these results offer a new mechanism for how ZIKV infection can cause neuropathology in the developing brain. Zika virus (ZIKV) infection of neural progenitor cells (NPCs) in utero is associated with neurological disorders, such as microcephaly, but a detailed molecular understanding of ZIKV-induced pathogenesis is lacking. Here we show that in vitro ZIKV infection of human cells, including NPCs, causes disruption of the nonsense-mediated mRNA decay (NMD) pathway. NMD is a cellular mRNA surveillance mechanism that is required for normal brain size in mice. Using affinity purification-mass spectrometry, we identified multiple cellular NMD factors that bind to the viral capsid protein, including the central NMD regulator up-frameshift protein 1 (UPF1). Endogenous UPF1 interacted with the ZIKV capsid protein in coimmunoprecipitation experiments, and capsid expression posttranscriptionally downregulated UPF1 protein levels, a process that we confirmed occurs during ZIKV infection. Cellular fractionation studies show that the ZIKV capsid protein specifically targets nuclear UPF1 for degradation via the proteasome. A further decrease in UPF1 levels by RNAi significantly enhanced ZIKV infection in NPC cultures, consistent with a model in which NMD restricts ZIKV infection in the fetal brain. We propose that ZIKV, via the capsid protein, has evolved a strategy to lower UPF1 levels and dampen antiviral activities of NMD, which in turn contributes to neuropathology in vivo.