Mechanisms of innate resistance to virus infections

项目摘要 人类细胞具有许多内在机制，可以抵抗外来病毒感染， 更好地了解这些自然过程将有助于我们与现有的 和突发病毒性疾病。干扰素诱导的跨膜蛋白（IFITMs）是细胞因子， 有效地阻止多种病毒的融合。它们以稳态存在于细胞中，并且也积累到 更高更有效的水平。IFITM3特别降低流感病毒的严重性 感染小鼠和人类。然而，我们目前缺乏对IFITM3 防止流感病毒融合。同样，我们也不完全了解控制 细胞中IFITM3的丰度。我们寻求弥合这些基本差距，我们的知识与两个具体的 这将使我们更接近设计基于IFITM3的抗病毒药物的长期目标。目标1将决定 IFITM3改变细胞膜以阻止病毒融合的分子机制。我们有新的 鉴定了IFITM3内的一个短的两亲性螺旋，我们表明它是抗病毒活性所必需的。鉴于 两亲性螺旋被很好地表征为诱导膜弯曲，我们将确定这种能力， 螺旋与膜结合并改变膜，并将确定其在抑制流感和其他病毒中的作用。 这项工作将提供第一个证据的两亲性为基础的IFITMs的行动机制。目的 2是基于我们的发现，细胞中IFITM3的稳态水平相反地被以下负调节： E3泛素连接酶NEDD4，受肿瘤抑制因子PTEN正调控。我们先前已经 显示NEDD4直接泛素化IFITM3，靶向其在溶酶体中降解。我们现在将 探讨PTEN促进IFITM3水平和对流感病毒感染的抵抗的机制。 我们将检测PTEN的哪种酶活性参与调节IFITM3，我们将确定是否 PTEN和NEDD4参与了相同的调节回路，最后，我们将研究PTEN和NEDD4的参与。 使用新产生的小鼠模型在IFITM3介导的体内抗感染中的PTEN。总的来说，这些 两个独立的目标将揭示控制IFITM3活性和细胞增殖的互补机制。 丰饶。

PROJECT SUMMARY Human cells possess many intrinsic mechanisms that provide resistance to incoming virus infections, and a better understanding of these natural processes would be valuable in our ongoing fight against existing and emergent viral diseases. The interferon-induced transmembrane proteins (IFITMs) are cellular factors that potently block the fusion of multiple viruses. They are present in cells at steady state and also accumulate to higher, more effective levels during infection. IFITM3 in particular reduces the severity of influenza virus infections in both mice and humans. However, we currently lack a mechanistic understanding of how IFITM3 prevents influenza virus fusion. Likewise, we do not fully understand the regulatory processes controlling the abundance of IFITM3 in cells. We seek to bridge these fundamental gaps in our knowledge with two specific aims that will bring us closer to our long-term goal of designing IFITM3-based antivirals. Aim 1 will determine the molecular mechanism by which IFITM3 alters cellular membranes to prevent virus fusion. We have newly identified a short amphipathic helix within IFITM3 that we show is required for antiviral activity. Given that amphipathic helices are well characterized to induce membrane curvature, we will determine the ability of this helix to associate with and alter membranes, and will define its role in inhibiting influenza and other viruses. This work will provide the first evidence for an amphipathicity-based mechanism of action for the IFITMs. Aim 2 is based on our discoveries that the steady state level of IFITM3 in cells is conversely negatively regulated by the E3 ubiquitin ligase NEDD4 and positively regulated by the tumor suppressor PTEN. We have previously shown that NEDD4 directly ubiquitinates IFITM3, targeting it for degradation in lysosomes. We will now interrogate the mechanism by which PTEN promotes IFITM3 levels and resistance to influenza virus infection. We will examine which enzymatic activity of PTEN is involved in regulating IFITM3, we will determine whether PTEN and NEDD4 are involved in the same regulatory circuit, and finally, we will examine the involvement of PTEN in IFITM3-mediated resistance to infection in vivo using newly generated mouse models. Overall, these two independent aims will reveal complementary mechanisms that control IFITM3 activity and cellular abundance.