Chen Biao, Guo Guijie, Wang Guoqing, Zhu Qianwen, Wang Lulu, Shi Wenhao, Wang Song, Chen Yuhai, Chi Xiaojuan, Wen Faxin, Maarouf Mohamed, Huang Shile, Yang Zhou, Chen Ji-Long
Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, People's Republic of China.
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, People's Republic of China.
PLoS Pathog. 2024 Jan 16;20(1):e1011958. doi: 10.1371/journal.ppat.1011958. eCollection 2024 Jan.
Autophagy-related protein 7 (ATG7) is an essential autophagy effector enzyme. Although it is well known that autophagy plays crucial roles in the infections with various viruses including influenza A virus (IAV), function and underlying mechanism of ATG7 in infection and pathogenesis of IAV remain poorly understood. Here, in vitro studies showed that ATG7 had profound effects on replication of IAV. Depletion of ATG7 markedly attenuated the replication of IAV, whereas overexpression of ATG7 facilitated the viral replication. ATG7 conditional knockout mice were further employed and exhibited significantly resistant to viral infections, as evidenced by a lower degree of tissue injury, slower body weight loss, and better survival, than the wild type animals challenged with either IAV (RNA virus) or pseudorabies virus (DNA virus). Interestingly, we found that ATG7 promoted the replication of IAV in autophagy-dependent and -independent manners, as inhibition of autophagy failed to completely block the upregulation of IAV replication by ATG7. To determine the autophagy-independent mechanism, transcriptome analysis was utilized and demonstrated that ATG7 restrained the production of interferons (IFNs). Loss of ATG7 obviously enhanced the expression of type I and III IFNs in ATG7-depleted cells and mice, whereas overexpression of ATG7 impaired the interferon response to IAV infection. Consistently, our experiments demonstrated that ATG7 significantly suppressed IRF3 activation during the IAV infection. Furthermore, we identified long noncoding RNA (lncRNA) GAPLINC as a critical regulator involved in the promotion of IAV replication by ATG7. Importantly, both inactivation of IRF3 and inhibition of IFN response caused by ATG7 were mediated through control over GAPLINC expression, suggesting that GAPLINC contributes to the suppression of antiviral immunity by ATG7. Together, these results uncover an autophagy-independent mechanism by which ATG7 suppresses host innate immunity and establish a critical role for ATG7/GAPLINC/IRF3 axis in regulating IAV infection and pathogenesis.
自噬相关蛋白7（ATG7）是一种重要的自噬效应酶。尽管众所周知自噬在包括甲型流感病毒（IAV）在内的多种病毒感染中发挥关键作用，但ATG7在IAV感染和发病机制中的功能及潜在机制仍知之甚少。在此，体外研究表明ATG7对IAV复制有深远影响。敲低ATG7显著减弱了IAV的复制，而ATG7的过表达则促进了病毒复制。进一步使用ATG7条件性敲除小鼠，结果显示与感染IAV（RNA病毒）或伪狂犬病病毒（DNA病毒）的野生型动物相比，它们对病毒感染具有显著抗性，表现为组织损伤程度较低、体重减轻较慢且存活率更高。有趣的是，我们发现ATG7以自噬依赖和非依赖的方式促进IAV复制，因为抑制自噬未能完全阻断ATG7对IAV复制的上调作用。为了确定自噬非依赖机制，利用转录组分析并证明ATG7抑制干扰素（IFN）的产生。在敲低ATG7的细胞和小鼠中，ATG7缺失明显增强了I型和III型IFN的表达，而ATG7的过表达则损害了对IAV感染的干扰素反应。一致地，我们的实验表明ATG7在IAV感染期间显著抑制IRF3激活。此外，我们确定长链非编码RNA（lncRNA）GAPLINC是参与ATG7促进IAV复制的关键调节因子。重要的是，ATG7导致的IRF3失活和IFN反应抑制均通过控制GAPLINC表达介导，这表明GAPLINC有助于ATG7抑制抗病毒免疫。总之，这些结果揭示了一种ATG7抑制宿主先天免疫的自噬非依赖机制，并确立了ATG7/GAPLINC/IRF3轴在调节IAV感染和发病机制中的关键作用。
