부산대학교 도서관

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. Author summary: Influenza A virus (IAV) causes acute respiratory diseases in human and animals, posing a great threat to public health. Autophagy plays crucial roles in viral infections including IAV, but mechanisms underlying interaction between autophagy and IAV remain ambiguous. Particularly, function and underlying mechanisms of ATG7, an essential autophagy effector enzyme, in viral infections are largely unexplored, and little information is available about relationship between ATG7 and IAV pathogenesis. Here, we used in vitro and in vivo models to address ATG7 function in the IAV infection and pathogenesis. We found that forced expression of ATG7 facilitates the viral replication, while depletion of ATG7 attenuates viral replication and renders mice more resistant to IAV or pseudorabies virus (PRV) infection. Importantly, we identify that ATG7 suppresses IRF3 activation and interferon production via lncRNA GAPLINC, revealing an autophagy-independent mechanism whereby ATG7 restrains host innate immunity and unveiling a critical role of ATG7/GAPLINC/IRF3 axis in regulating IAV pathogenesis. Moreover, our observations suggest that ATG7 may positively regulate the expression of GAPLINC via suppression of NF-κB activation during IAV infection. Together, these results reveal that ATG7 has multiple biological roles beyond autophagy, and provide an important insight into the complicated interplay between host and IAV. [ABSTRACT FROM AUTHOR]