Guangxi Key Laboratory of AIDS Prevention and Treatment & Guangxi Universities Key Laboratory of Prevention and Control of Highly Prevalent Disease, School of Public Health, Guangxi Medical University, Nanning, 530021, Guangxi, China.
Geriatrics Digestion Department of Internal Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China.
Cell Death Dis. 2018 Sep 5;9(9):898. doi: 10.1038/s41419-018-0845-x.
Both alcohol and hepatitis C virus (HCV) infection could induce cellular autophagy in liver cells, which is considered to be essential for productive HCV replication. However, whether alcohol-induced autophagy is involved in the pathogenesis of HCV infection is still poorly understood. Alcohol treatment could induce autophagy in Huh7 cells (a hepatoma cell line that supports HCV JFH-1 replication), evidenced by the increase of LC3B-II levels, the conversion of LC3B-I to LC3B-II, and the formation of GFP-LC3 puncta as well as the decrease of p62 level in alcohol-treated cells compared with control cells. Alcohol treatment also significantly increased PIASy (a member of the PIAS family) expression, which can act as a SUMO (small ubiquitin-like modifier protein) E3 ligase to regulate a broader range of cellular processes including autophagy. Overexpression or the silencing expression of PIASy in alcohol-treated Huh7 cells could increase or decrease autophagic activation caused by alcohol treatment, respectively, and thus affect HCV replication correspondingly. In the absence of alcohol, overexpression or silencing expression of PIASy increase or decrease the level of cellular autophagy, judged by the changes of LC3B-II and p62 levels in the presence or absence of chloroquine (CQ), a lysosome inhibitor. More importantly, in the presence of 3-methyladenine (3-MA), an inhibitor in the early stage of autophagy, the effects of overexpression or silencing expression of PIASy on HCV replication were largely blocked. Furthermore, PIASy could selectively drive the accumulation of SUMO1-conjugated proteins, along with upregulation of the expression of several important autophagy factors, including ATG7 and ATG5-ATG12. In conclusion, alcohol promotes HCV replication through activation of autophagy in Huh7 cells, which partly attributes to its induction of PIASy expression. PIASy-enhanced accumulation of SUMO1-conjugated proteins may contribute to its inducing effect of autophagy. Our findings provide a novel mechanism for the action of alcohol-promoting HCV replication in the context of cellular autophagy.
酒精和丙型肝炎病毒（HCV）感染均可诱导肝细胞发生自噬，这被认为对 HCV 的复制是必需的。然而，酒精诱导的自噬是否参与 HCV 感染的发病机制尚不清楚。酒精处理可诱导 Huh7 细胞（一种支持 HCV JFH-1 复制的肝癌细胞系）发生自噬，这表现在 LC3B-II 水平增加、LC3B-I 向 LC3B-II 的转化、GFP-LC3 斑点的形成以及与对照细胞相比，酒精处理细胞中 p62 水平降低。酒精处理还显著增加了 PIASy（PIAS 家族的一员）的表达，PIASy 可以作为 SUMO（小泛素样修饰蛋白）E3 连接酶，调节包括自噬在内的更广泛的细胞过程。在酒精处理的 Huh7 细胞中过表达或沉默表达 PIASy 分别可增加或减少酒精处理引起的自噬激活，从而相应地影响 HCV 复制。在没有酒精的情况下，通过在有或没有氯喹（CQ，溶酶体抑制剂）的情况下 LC3B-II 和 p62 水平的变化来判断，过表达或沉默表达 PIASy 会增加或减少细胞自噬的水平。更重要的是，在自噬早期阶段的抑制剂 3-甲基腺嘌呤（3-MA）存在的情况下，过表达或沉默表达 PIASy 对 HCV 复制的影响在很大程度上被阻断。此外，PIASy 可以选择性地驱动 SUMO1 缀合蛋白的积累，同时上调几个重要的自噬因子的表达，包括 ATG7 和 ATG5-ATG12。总之，酒精通过激活 Huh7 细胞中的自噬来促进 HCV 复制，这部分归因于其诱导 PIASy 的表达。PIASy 增强的 SUMO1 缀合蛋白的积累可能有助于其诱导自噬的作用。我们的研究结果为酒精在细胞自噬背景下促进 HCV 复制的作用提供了一种新的机制。
