College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.
Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China.
Microbiol Spectr. 2023 Jun 15;11(3):e0318622. doi: 10.1128/spectrum.03186-22. Epub 2023 Mar 29.
Japanese encephalitis virus (JEV) is a typical mosquito-borne flavivirus that can cause central nervous system diseases in humans and animals. Host factors attempt to limit virus replication when the viruses invade the host by using various strategies for replication. It is essential to clarify the host factors that affect the life cycle of JEV and explore its underlying mechanism. Here, we found that USP1-associated factor 1 (UAF1; also known as WD repeat-containing protein 48) modulated JEV replication. We found that JEV propagation significantly increased in UAF1-depleted Huh7 cells. Moreover, we found that knockdown of UAF1 activated cell autophagic flux in further functional analysis. Subsequently, we demonstrated that autophagy can be induced by JEV, which promotes viral replication by inhibiting interferon-stimulated gene (ISG) expression in Huh7 cells. The knockdown of UAF1 reduced ISG expression during JEV infection. To explore the possible roles of autophagy in UAF1-mediated inhibition of JEV propagation, we knocked out ATG7 to generate autophagy-deficient cells and found that depletion of UAF1 failed to promote JEV replication in ATG7 knockout cells. Moreover, in ATG7-deficient Huh7 cells, interference with UAF1 expression did not lead to the induction of autophagy. Taken together, these findings indicate that UAF1 is a critical regulator of autophagy and reveal a mechanism by which UAF1 knockdown activates autophagy to promote JEV replication. Host factors play an essential role in virus replication and pathogenesis. Although UAF1 is well known to form complexes with ubiquitin-specific proteases, little is known about the function of the UAF1 protein itself. In this study, we confirmed that UAF1 is involved in JEV replication. Notably, we discovered a novel function for UAF1 in regulating autophagy. Furthermore, we demonstrated that UAF1 modulated JEV replication through its autophagy regulation. This study is the first description of the novel function of UAF1 in regulating autophagy, and it clarifies the underlying mechanism of the antiviral effect of UAF1 against JEV. These results provide a new mechanistic insight into the functional annotation of UAF1 and provide a potential target for increasing virus production during vaccine production.
日本脑炎病毒（JEV）是一种典型的蚊媒黄病毒，可引起人类和动物的中枢神经系统疾病。当病毒侵入宿主时，宿主因素会通过各种复制策略来限制病毒的复制。阐明影响 JEV 生命周期的宿主因素并探索其潜在机制至关重要。在这里，我们发现 U 泛素特异性蛋白酶 1 相关因子 1（UAF1；也称为 WD 重复蛋白 48）调节 JEV 复制。我们发现，在 UAF1 耗尽的 Huh7 细胞中，JEV 的增殖显著增加。此外，在进一步的功能分析中，我们发现 UAF1 的敲低激活了细胞自噬流。随后，我们证明 JEV 可以诱导自噬，通过抑制 Huh7 细胞中干扰素刺激基因（ISG）的表达促进病毒复制。在 JEV 感染过程中，UAF1 的敲低降低了 ISG 的表达。为了探讨自噬在 UAF1 介导的抑制 JEV 增殖中的可能作用，我们敲除了 ATG7 以产生自噬缺陷细胞，并发现 UAF1 的耗尽不能促进 ATG7 敲除细胞中的 JEV 复制。此外，在 ATG7 缺陷型 Huh7 细胞中，干扰 UAF1 表达不会导致自噬的诱导。总之，这些发现表明 UAF1 是自噬的关键调节剂，并揭示了 UAF1 敲低通过激活自噬促进 JEV 复制的机制。宿主因素在病毒复制和发病机制中起着至关重要的作用。尽管 UAF1 是众所周知的与泛素特异性蛋白酶形成复合物，但对 UAF1 蛋白本身的功能知之甚少。在这项研究中，我们证实 UAF1 参与了 JEV 的复制。值得注意的是，我们发现了 UAF1 调节自噬的新功能。此外，我们证明 UAF1 通过调节自噬来调节 JEV 的复制。这项研究首次描述了 UAF1 在调节自噬方面的新功能，并阐明了 UAF1 对 JEV 抗病毒作用的潜在机制。这些结果为 UAF1 的功能注释提供了新的机制见解，并为疫苗生产过程中增加病毒产量提供了潜在的目标。
