Reovirus Modulation of the Cardiac Innate Response: Type I Interferon and HSP25

抽象的。我们的总体目标是确定宿主先天抗病毒的新成分 病毒通过破坏这种反应而引起疾病的反应和新机制。 心肌细胞是不可补充的；因此心脏不寻常地依赖于这一线。 防守。事实上，我们已经证明了心脏I型干扰素(干扰素)的反应是独特的， 在呼肠孤病毒诱导的小鼠心肌炎中，不同病毒株的干扰素反应不同 对保护来说至关重要。我们继续使用这个强大的病毒工具包来探测 心脏是一个非常脆弱的器官，它的先天反应有了两个新发现。 首先，我们发现呼肠孤病毒通过一种以前没有展示过的机制抑制干扰素信号。 任何病毒。具体来说，呼肠孤病毒蛋白2抑制干扰素信号，抑制是病毒 与转录因子IRF9的异常核积累有关， 可能反映了对其正常参与干扰素诱导的伴随干扰- 受刺激的基因。我们假设呼肠孤病毒蛋白2调节IRF9的结构/功能 为了抑制干扰素信号，需要抑制心肌细胞中的干扰素信号。 心肌炎。在具体的目标1中，我们将：i)确定2是否改变了IRF9的结构或细胞 结合伙伴；ii)确定IRF9效应所需的2和IRF9结构域，以及iii)确定 呼肠孤病毒诱导的心肌炎是否需要IRF9的调节？第二，使用 蛋白质组发现方法，我们发现了一种新的干扰素非依赖性保护反应 它可以被病毒颠覆。我们发现呼肠孤病毒诱导磷酸化(非 心肌呼肠孤病毒)或热休克蛋白-25(HSP25)的降解(心肌呼肠孤病毒) 这是细胞类型特异性的，不依赖于干扰素。七人组成员 病毒家族诱导HSP25表达或磷酸化，但不能降解，但只有一个 研究已经解决了HSP25的抗病毒作用。许多心脏损伤可诱发HSP25 磷酸化而不是降解，以及过度表达的HSP25可以保护人们免受压力- 导致心脏损伤。我们假设HSP25发挥特定细胞类型的抗病毒作用， 磷酸化的HSP25是抗病毒的，病毒已经进化出逃避病毒的机制 这种与生俱来的反应。在特定目标2中，我们将确定：i)呼肠孤病毒的细胞类型特异性 HSP25的改变，ii)呼肠孤病毒改变HSP25的机制，以及iii)通过 哪种HSP25抑制呼肠孤病毒感染。我们研究的更广泛影响是增加了 可被病毒破坏的保护性主机因素目录，可能提供新的 治疗目标，特别是对病毒性心肌炎，这仍然是一种顽固的疾病。

ABSTRACT. Our overall goal is to identify novel components of the host innate antiviral response and novel mechanisms by which viruses subvert this response to cause disease. Cardiac myocytes are non-replenishable; thus the heart is unusually dependent on this first-line defense. Indeed, we have shown that the cardiac Type I interferon (IFN) response is unique, and that in reovirus-induced murine myocarditis the IFN response differs between virus strains and is critical for protection. We continue to use this powerful tool-kit of viruses to probe the innate response in a highly vulnerable organ, the heart, and have made two new discoveries. First, we found that reovirus inhibits IFN signaling by a mechanism not previously shown for any virus. Specifically, reovirus protein ¿2 represses IFN signaling, and repression is virus strain-specific and is associated with unusual nuclear accumulation of transcription factor IRF9, likely reflecting concomitant interference with its normal participation in induction of IFN- stimulated genes. We hypothesize that reovirus protein ¿2 modulates IRF9 structure / function to inhibit IFN signaling, and that ¿2 repression of IFN signaling in cardiac cells is required for myocarditis. In Specific Aim 1, we will: i) determine whether ¿2 alters IRF9 structure or cellular binding partners; ii) identify ¿2 and IRF9 domains required for IRF9 effects, and iii) determine whether ¿2 modulation of IRF9 is required for reovirus-induced myocarditis. Second, using a proteomic discovery approach, we identified a new IFN-independent protective response which can be subverted by virus. We found that reoviruses induce phosphorylation (non- myocarditic reovirus) or degradation (myocarditic reovirus) of Heat Shock Protein-25 (HSP25) in cardiac myocytes, and that this is cell type-specific and IFN-independent. Members of seven virus families induce HSP25 expression or phosphorylation but not degradation, yet only one study has addressed HSP25 antiviral effects. Many cardiac insults induce HSP25 phosphorylation but not degradation, and over-expressed HSP25 protects against stress- induced cardiac damage. We hypothesize that HSP25 plays a cell type-specific antiviral role, that phosphorylated HSP25 is antiviral, and that viruses have evolved mechanisms to evade this innate response. In Specific Aim 2, we will determine: i) cell type-specificity for reovirus alteration of HSP25, ii) mechanisms by which reovirus alters HSP25, and iii) mechanisms by which HSP25 inhibits reovirus infection. The broader impact of our studies is to increase the catalog of protective host factors that can be sabotaged by viruses, potentially providing new therapeutic targets, particularly for viral myocarditis which remains an intractable disease.