Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 81362, Taiwan.
Department and Graduate Institute of Microbiology and Immunology, National Defense Medical Center, Taipei 11490, Taiwan.
Theranostics. 2020 Jul 14;10(20):9200-9213. doi: 10.7150/thno.47077. eCollection 2020.
Autophagy is an essential, homeostatic process by which cells break down their own components, it also contributes to restricting bacterial infection in host defense systems; yet, how autophagy regulates viral infection remains inconclusive. Aichi virus (AiV), belonging to the genus Kobuvirus in the family, causes acute gastroenteritis in human. The role of autophagy-mediated anti-viral activity on AiV infection was investigated in this study. The effect of autophagy-associated molecules in retinoic acid-inducible gene-I (RIG-I)-like receptor (RLR) antiviral signal axis was analyzed in AiV infected cells by using biochemistry and pharmacologic approaches. In addition, the AiV viral protein regulating autophagy-associated RLR activity was also evaluated. : In AiV-infected cells, autophagic flux including the formation of autophagic vacuoles, as well as degradation of microtubule-associated protein light chain 3 (LC3) and sequestosome-1 (SQSTM1/p62) were observed. Ectopic overexpression of LC3 and p62, but not Atg proteins, contributed to RLR antiviral signal axis, shRNA knockdown of LC3 and p62 led to a downregulation of antiviral inflammation. Moreover, AiV infection inhibited double-stranded RNA (dsRNA)-activated RLR activity by the viral protein 3C protease but not H42D, C143S protease dead mutants. AiV 3C protease caused the degradation of LC3 and p62, and also RLR signal proteins. This study reveals a possible mechanism of autophagy-associated proteins regulating virus replication. Maintaining a cellular level of LC3 and p62 during the viral infection period might help restrict virus replication. Although, AiV 3C protease dampens the LC3 and p62-mediated host antiviral machinery for AiV replication. Results obtained provide a better understanding of the molecular pathogenesis of AiV for developing methods of prevention and treatment.
自噬是一种重要的、维持细胞内稳态的过程，细胞通过该过程分解自身成分，该过程还有助于宿主防御系统限制细菌感染；然而，自噬如何调节病毒感染仍未定论。Aichi 病毒（AiV）属于杯状病毒科，是科巴病毒属的一员，会引起人类急性肠胃炎。本研究旨在探讨自噬介导的抗病毒活性对 AiV 感染的影响。本研究通过生物化学和药理学方法分析了自噬相关分子在视黄酸诱导基因-I（RIG-I）样受体（RLR）抗病毒信号轴中的作用，以及 AiV 病毒蛋白对自噬相关 RLR 活性的调节作用。在 AiV 感染的细胞中，观察到自噬流，包括自噬小体的形成，以及微管相关蛋白轻链 3（LC3）和自噬相关蛋白 1（p62）的降解。LC3 和 p62 的异位过表达有助于 RLR 抗病毒信号轴，而 LC3 和 p62 的 shRNA 敲低则导致抗病毒炎症的下调。此外，AiV 感染通过病毒蛋白 3C 蛋白酶而非 H42D、C143S 蛋白酶失活突变体抑制双链 RNA（dsRNA）激活的 RLR 活性。AiV 3C 蛋白酶导致 LC3 和 p62 的降解，以及 RLR 信号蛋白的降解。本研究揭示了自噬相关蛋白调节病毒复制的一种可能机制。在病毒感染期间维持细胞内 LC3 和 p62 的水平可能有助于限制病毒复制。然而，AiV 3C 蛋白酶抑制了 LC3 和 p62 介导的宿主抗病毒机制，从而促进了 AiV 的复制。本研究结果为 AiV 的分子发病机制提供了更好的理解，为开发预防和治疗方法提供了依据。
