MafF Is an Antiviral Host Factor That Suppresses Transcription from Hepatitis B Virus Core Promoter
MafF Is an Antiviral Host Factor That Suppresses Transcription from Hepatitis B Virus Core Promoter
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DOI：
10.1128/jvi.00767-21
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发表时间：
2021-08-01
影响因子：
5.4
通讯作者：
Wakita, Takaji
中科院分区：
文献类型：
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作者：
Ibrahim, Marwa K.;Abdelhafez, Tawfeek H.;Wakita, Takaji
B型肝炎病毒（HBV）是一种隐形病毒，其仅表现出对干扰素系统的最小诱导，而干扰素系统是先天性和适应性免疫应答两者所需的。然而，90%的急性感染成人可以清除病毒，这表明存在促进病毒清除的其他机制。在这里，我们报告，Maf bZIP转录因子F（MafF）促进宿主防御HBV感染。使用小干扰RNA（siRNA）文库和HBV/NanoLuc（NL）报告病毒，我们筛选以鉴定抗HBV宿主因子。我们的数据表明，沉默MafF导致HBV/NL感染后荧光素酶活性增加6倍。MafF的过表达降低了HBV核心启动子的转录活性，这在假定的MafF结合区突变后得到缓解。通过CRISPR/Cas9编辑（在HepG 2-hNTCP-C4细胞中）或siRNA沉默（在原代肝细胞[PXB细胞]中）导致的MafF表达缺失分别诱导HBV感染后的HBV核心RNA和HBV前基因组RNA（pgRNA）水平。MafF与HBV核心启动子物理结合，并竞争性抑制HNF-4 α与HBV增强子II序列（EnhII）中的重叠序列结合，如染色质免疫沉淀（ChIP）分析所示。在HepG 2和PXB细胞中，以NF-κ B依赖的方式，通过白细胞介素-β（IL-β）或肿瘤坏死因子-α（TNF-α）处理诱导MafF表达。一致的是，MafF的表达水平在慢性HBV感染患者中显著增强，并且与这些细胞因子的水平呈正相关，尤其是在免疫清除阶段。重要信息HBV是慢性肝病的主要原因，全球约有2.5亿人感染。HBV已经开发出逃避干扰素依赖性先天免疫反应的策略。因此，识别其他抗HBV机制对于理解HBV发病机制和开发抗HBV策略是重要的。MafF显示抑制HBV核心启动子的转录，导致HBV生命周期的显著抑制。此外，在慢性HBV患者和原代人肝细胞（PXB细胞）中诱导MafF表达。这种诱导与炎性细胞因子（IL-β和TNF-α）的水平相关。这些数据表明MafF的诱导通过抑制来自选定的病毒启动子的转录而有助于宿主的抗病毒防御。我们的数据揭示了MafF作为抗HBV宿主限制因子的新作用。
Hepatitis B virus (HBV) is a stealth virus that exhibits only minimal induction of the interferon system, which is required for both innate and adaptive immune responses. However, 90% of acutely infected adults can clear the virus, suggesting the presence of additional mechanisms that facilitate viral clearance. Here, we report that Maf bZIP transcription factor F (MafF) promotes host defense against infection with HBV. Using a small interfering RNA (siRNA) library and an HBV/NanoLuc (NL) reporter virus, we screened to identify anti-HBV host factors. Our data showed that silencing of MafF led to a 6-fold increase in luciferase activ-ity after HBV/NL infection. Overexpression of MafF reduced HBV core promoter tran-scriptional activity, which was relieved upon mutation of the putative MafF binding region. Loss of MafF expression through CRISPR/Cas9 editing (in HepG2-hNTCP-C4 cells) or siRNA silencing (in primary hepatocytes [PXB cells]) induced HBV core RNA and HBV pregenomic RNA (pgRNA) levels, respectively, after HBV infection. MafF physically binds to the HBV core promoter and competitively inhibits HNF-4 alpha binding to an overlapping sequence in the HBV enhancer II sequence (EnhII), as seen by chromatin immunopreci-pitation (ChIP) analysis. MafF expression was induced by interleukin-beta (IL-beta) or tu-mor necrosis factor alpha (TNF-alpha) treatment in both HepG2 and PXB cells, in an NF-kappa B-dependent manner. Consistently, MafF expression levels were significantly enhanced and positively correlated with the levels of these cytokines in patients with chronic HBV infection, especially in the immune clearance phase.IMPORTANCE HBV is a leading cause of chronic liver diseases, infecting about 250 million people worldwide. HBV has developed strategies to escape interferon -de-pendent innate immune responses. Therefore, the identification of other anti-HBV mechanisms is important for understanding HBV pathogenesis and developing anti-HBV strategies. MafF was shown to suppress transcription from the HBV core promoter, leading to significant suppression of the HBV life cycle. Furthermore, MafF expression was induced in chronic HBV patients and in primary human hepatocytes (PXB cells). This induction correlated with the levels of inflammatory cytokines (IL-beta and TNF-alpha). These data suggest that the induction of MafF contributes to the host's antiviral defense by suppressing transcription from selected viral promoters. Our data shed light on a novel role for MafF as an anti-HBV host restriction factor.