Yu Lei, Jiang Yong, Rang Hongyu, Wang Xueyun, Cai Yumeng, Yan Haojie, Wu Shuwen, Lan Ke
Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China.
State Key Laboratory of Virology and Biosafety, College of Life Sciences, Wuhan University, Wuhan, China.
J Virol. 2025 Apr 15;99(4):e0013325. doi: 10.1128/jvi.00133-25. Epub 2025 Mar 27.
The balance between cellular defense and viral escape determines the fate of influenza A virus (IAV) infection. Viral polymerase activity is critical for the replication and propagation of IAV. The antiviral strategies of host cells against IAV infection have not been fully elucidated. Here, we identified DCAF7 as an antiviral factor for IAV, which inhibits the replication of H1N1 and H3N2. Mechanistically, DCAF7 weakens the viral heterotrimer polymerase activity and restricts IAV replication and transcription. DCAF7 as a substrate recognition receptor forms a complete CRL4B E3 ligase with the CRL4B E3 complex to promote K48-linked polyubiquitination of the viral polymerase subunit PA at the K609 site and its degradation. We also showed that a specific cullin-RING E3 ligase (CRL) inhibitor MLN4924 upregulates the protein level of PA and promotes the replication of IAV . Moreover, activation of CUL4B by etoposide promotes the degradation of PA and inhibits IAV replication . Importantly, we found that viral NS1 protein decreases DCAF7 level to impair its antiviral efficacy. Taken together, these findings reveal a new mechanism of host resistance to IAV infection and suggest that regulation of the DCAF7-CRL4B axis is a potential target for antivirals.
Until now, the key host factors that affect IAV polymerase have not been fully elucidated. In this study, we identified host DCAF7 as a novel restriction factor for IAV replication. Importantly, DCAF7 acts as a substrate recognition receptor to recruit CRL4B E3 ligase to mediate the degradation of PA through the ubiquitin-proteasome pathway. Further exploration demonstrated that a specific cullin-RING E3 ligase inhibitor MLN4924 promotes IAV replication , and activation of CUL4B by etoposide inhibits IAV replication . Notably, we found that the viral NS1 protein decreases DCAF7 level to impair its antiviral efficacy. These findings elucidate the critical function and mechanism of the DCAF7-CRL4B axis in IAV replication, reveal a novel host anti-IAV mechanism, and provide new anti-influenza drug development strategies.
细胞防御与病毒逃逸之间的平衡决定了甲型流感病毒（IAV）感染的命运。病毒聚合酶活性对于IAV的复制和传播至关重要。宿主细胞针对IAV感染的抗病毒策略尚未完全阐明。在此，我们鉴定出DCAF7是IAV的一种抗病毒因子，它可抑制H1N1和H3N2的复制。从机制上讲，DCAF7会削弱病毒异源三聚体聚合酶活性，并限制IAV的复制和转录。DCAF7作为底物识别受体与CRL4B E3复合物形成完整的CRL4B E3连接酶，以促进病毒聚合酶亚基PA在K609位点的K48连接的多聚泛素化及其降解。我们还表明，一种特异性的cullin-RING E3连接酶（CRL）抑制剂MLN4924会上调PA的蛋白水平并促进IAV的复制。此外，依托泊苷对CUL4B的激活会促进PA的降解并抑制IAV的复制。重要的是，我们发现病毒NS1蛋白会降低DCAF7水平，从而损害其抗病毒功效。综上所述，这些发现揭示了宿主抵抗IAV感染的新机制，并表明对DCAF7-CRL4B轴的调控是抗病毒药物的一个潜在靶点。
到目前为止，影响IAV聚合酶的关键宿主因子尚未完全阐明。在本研究中，我们鉴定出宿主DCAF7是IAV复制的一种新型限制因子。重要的是，DCAF7作为底物识别受体，可募集CRL4B E3连接酶，通过泛素-蛋白酶体途径介导PA的降解。进一步的探索表明，一种特异性的cullin-RING E3连接酶抑制剂MLN4924会促进IAV的复制，而依托泊苷对CUL4B的激活会抑制IAV的复制。值得注意的是，我们发现病毒NS1蛋白会降低DCAF7水平，从而损害其抗病毒功效。这些发现阐明了DCAF7-CRL4B轴在IAV复制中的关键功能和机制，揭示了一种新型的宿主抗IAV机制，并提供了新的抗流感药物研发策略。
