ZFAND6 regulation of innate antiviral immunity

摘要 A20泛素编辑酶是NF-κB和先天免疫信号传导途径的关键负调节因子。 A20含有7个锌指（ZF 1 -7）结构域，其中ZF 4与赖氨酸63（K63）连接的 多聚泛素链以抑制NF-κB信号传导。包括A20在内，有10个基因含有A20 ZF 结构域编码的人类基因组;然而，除了A20，这些蛋白质的功能 我们对此知之甚少。ZFAND 6（也称为AWP 1）含有A20样ZF结构域，其与A20样ZF结构域具有显著的同源性。 与A20 ZF 4具有序列同源性，并且还具有AN 1型ZF。虽然已发表的过度表达 研究表明，ZFAND 6可能抑制NF-κB，这是由ZFAND 6调节的特异性途径， 生理作用仍然难以捉摸。在这个探索性建议的初步研究中，我们使用了 基因靶向以产生缺乏Zfand 6基因的小鼠。Zfand 6-/-小鼠出生于预期的孟德尔 没有明显的发育或免疫异常的频率。Zfand 6-/- bone的RNA测序 骨髓源性巨噬细胞显示干扰素刺激基因（ISGs）的自发诱导， 使这些细胞对各种DNA和RNA病毒的感染具有高度抗性。的DNA 敏感通路接头STING和抗病毒转录因子IRF 1在Zfand 6-/-中均上调， 细胞，这可能驱动ZFAND 6缺陷细胞对病毒感染的抗性。ISG在小鼠中表达上调， Zfand 6-/-小鼠和基因敲除小鼠的脾脏比野生型小鼠更易感，但肺中没有 尽管病毒载量相当，但低剂量甲型流感病毒（IAV）攻击后死亡率。 因此，ZFAND 6的缺失可能扰乱免疫稳态并加剧病毒诱导的炎症， 免疫病理学推动这些研究的中心假设是，ZFAND 6靶向关键的先天性 免疫信号蛋白降解，以防止ISG的自发诱导， 病毒感染引发的过度炎症。为了解决这个假设，我们将执行 1）确定ZFAND 6抑制抗病毒信号传导的机制，和2） 确定ZFAND 6在调节对IAV感染的炎症反应中的作用。完成这些 研究将确定ZFAND 6在限制先天性抗病毒免疫中的生理作用，并扩大我们的研究范围。 免疫稳态机制的知识，有助于减轻病毒引起的炎症。

ABSTRACT The A20 ubiquitin-editing enzyme is a key negative regulator of NF-κB and innate immune signaling pathways. A20 contains seven zinc finger (ZF1-7) domains, of which ZF4 interacts with lysine 63 (K63)-linked polyubiquitin chains to suppress NF-κB signaling. Including A20, there are 10 genes containing A20 ZF domains encoded in the human genome; however, with the exception of A20 the functions of these proteins are poorly understood. ZFAND6 (also known as AWP1) contains an A20-like ZF domain that shares significant sequence homology with A20 ZF4, and also harbors an AN1-type ZF. Although published overexpression studies suggest that ZFAND6 may inhibit NF-κB, the specific pathways regulated by ZFAND6 and its physiological roles have remained elusive. In preliminary studies for this exploratory proposal, we have used gene targeting to generate mice lacking the Zfand6 gene. Zfand6–/– mice are born at expected Mendelian frequencies with no obvious developmental or immune abnormalities. RNA sequencing of Zfand6–/– bone marrow-derived macrophages revealed spontaneous induction of interferon-stimulated genes (ISGs), which rendered these cells highly resistant to infection with a broad range of DNA and RNA viruses. The DNA sensing pathway adaptor STING and the antiviral transcription factor IRF1 were both upregulated in Zfand6–/– cells, which may drive the resistance of ZFAND6-deficient cells to virus infection. ISGs were upregulated in the spleen, but not in the lungs, of Zfand6–/– mice, and knockout mice were more susceptible than wild-type mice to mortality upon challenge with a low dose of influenza A virus (IAV) despite comparable viral loads. Therefore, loss of ZFAND6 may perturb immune homeostasis and exacerbate virus-induced inflammation and immunopathology. The central hypothesis driving these investigations is that ZFAND6 targets key innate immune signaling proteins for degradation to prevent the spontaneous induction of ISGs which may contribute to overexuberant inflammation triggered by virus infection. To address this hypothesis we will perform the following Specific Aims: 1) Determine the mechanisms of ZFAND6 inhibition of antiviral signaling, and 2) Determine the role of ZFAND6 in regulating the inflammatory response to IAV infection. Completion of these studies will define a physiological role for ZFAND6 in restricting innate antiviral immunity and expand our knowledge on the mechanisms of immune homeostasis which serve to mitigate virus-induced inflammation.