Cellular determinants of apoptosis in virus-infected cells

项目描述（由申请人提供）：该项目的目标是研究新发现的抗病毒途径是如何被激活和调节的，以及它在决定病毒发病机制和持久性中的作用。I型干扰素（IFN）系统在先天抗病毒反应中起主要作用。病毒感染激活转录因子IRF-3，该因子负责诱导IFN和其他抗病毒蛋白。我们最近的调查显示

DESCRIPTION (provided by applicant): The goal of the project is to investigate how a newly discovered antiviral pathway is activated and regulated and what its role is in determining viral pathogenesis and persistence. The type I interferon (IFN) system plays a major role in innate antiviral response. Virus infection activates the transcription factor IRF-3, which is responsible for the induction of IFN and other antiviral proteins. Recent investigation by us has revealed that IRF-3 also activates an IFN-independent pro-apoptotic pathway, named RIPA (RIG-I-activated IRF-3-mediated Pathway of Apoptosis). To trigger RIPA, activated IRF-3 binds Bax and translocates it to mitochondria to cause apoptosis; the two functions of IRF-3 are genetically separable. RIPA is activated by many RNA and DNA viruses and inhibits both viral replication and pathogenesis. RIPA is temporally regulated through the action of XIAP and PI3 kinase, which is also activated upon virus infection. In the absence of RIPA, viruses establish persistent infection. Here we propose to investigate RIPA further. In Aim 1, we will investigate how IRF-3 is activated in RIPA as a consequence of phosphorylation of specific serine residues and ubiquitynation of specific lysine residues. Genetic and biochemical analyses will be used for this purpose. In Aim 2, we will investigate how viruses evade RIPA temporarily, by triggering negative regulation of RIPA though activation of the epidermal growth factor receptor, which in turn activates PI3 kinase. In Aim 3, we will investigate the physiological relevance of RIPA in determining the outcome of virus infection. Mutant cells defective in one, but not the other, action of IRF-3, will be used for measuring the role of RIPA on the efficiency of virus replication and establishing viral persistence. Finally, genetically modified mice, including new IRF-3 mutant knock-in mice which have been generated for this project, will be used to assess the in vivo contribution of RIPA in controlling viral pathogenesis.