Supplementary Material for: Inducible GBP5 Mediates the Antiviral Response via Interferon-Related Pathways during Influenza A Virus Infection

Guanylate binding protein (GBP) 5 belongs to the GBP family, which is involved in important cellular processes, including signal transduction, translation, vesicle trafficking, and exocytosis. Structurally, GBPs display a high degree of homology and share highly conserved GTP-binding or hydrolysis domains. GBP5 was reported to be a critical cellular factor in inflammasome assembly. However, little is known about its role in the host antiviral innate immune response. In this study, we found that GBP5 expression was significantly elevated in influenza patients and influenza A virus-infected A549 human lung epithelial cells. The overexpression of GBP5 inhibited virus replication by enhancing the expression of virus-induced interferon (IFN) and IFN-related effectors. Knockdown of GBP5 had the opposite effect. Moreover, GBP5 enhanced endogenous IFN expression by interacting with the NF-κB-essential modulator complex and stimulating NF-κB signaling. Additionally, the expression of proinflammatory factors, such as IL-6, IL-8, tumor necrosis factor-α, cyclooxygenase-2, and inducible nitric oxide synthase, was also activated by GBP5. Taken together, our results reveal that GBP5 inhibited virus replication through the activation of IFN signaling and proinflammatory factors.鸟苷酸结合蛋白5（GBP5）属于鸟苷酸结合蛋白（GBP）家族，该家族参与诸多重要细胞生物学过程，包括信号转导、翻译、囊泡运输及胞吐作用。结构层面上，GBP家族成员具有高度同源性，且共享高度保守的GTP结合或水解结构域。已有研究证实，GBP5是炎性小体组装过程中的关键细胞因子。然而，目前关于其在宿主抗病毒天然免疫应答中的作用尚不明晰。本研究发现，流感患者及甲型流感病毒感染的人肺上皮A549细胞中，GBP5的表达水平显著升高。过表达GBP5可通过上调病毒诱导型干扰素（Interferon，IFN）及其相关效应分子的表达，抑制病毒复制；而敲低GBP5则会产生相反效果。此外，GBP5可通过与NF-κB必需调节蛋白复合物相互作用并激活NF-κB信号通路，增强内源性IFN的表达。同时，IL-6、IL-8、肿瘤坏死因子-α、环氧合酶-2及诱导型一氧化氮合酶等促炎因子的表达亦可被GBP5激活。综上，本研究结果表明，GBP5可通过激活IFN信号通路与促炎因子，实现对病毒复制的抑制。