Alterations in the surfaceome of the herpes simplex virus 1 infected cells via the Cbl/CIN85 endocytic machinery and the role of the Infected Cell Protein No 0 (ICP0) in endocytosis.

单纯疱疹病毒1型已经困扰了80%以上的人口，并可导致从良性唇疱疹到脑炎等严重程度不等的疾病。在粘膜上皮细胞复制后，病毒在支配感染组织的感觉神经元中建立了潜伏的储备库。在应激或免疫反应减弱时，这些神经元中的病毒重新激活是复发疾病中的病毒来源。为了感染宿主并在宿主中持续存在，HSV-1进化出了对抗宿主抗病毒反应的策略。病毒感染细胞的即刻早期蛋白0(ICP0)在这一过程中起着基础性的作用。在体内，ICP0对于宿主的成功定植、病毒复制以及有效地从神经元潜伏期重新激活病毒是必不可少的。在感染的早期阶段，ICP0定位于细胞核，通过阻断病毒基因组的阻遏物，通过诱导病毒染色质重塑和抑制抗病毒反应来激活病毒基因的转录。病毒复制的开始会触发ICP0移位到细胞质，在病毒复制周期的剩余时间里，ICP0一直驻留在细胞质中。对于ICP0在核外的功能，人们的研究还很少。胞质中的ICP0与Cbl E3连接酶的结合配对蛋白CIN85相互作用，CIN85在细胞表面受体内化、内吞加工和蛋白质分选中起重要作用。病毒似乎通过ICP0抑制内吞机制Cb1/CIN85，以消除表面成分，这些成分可能会引发有害信号，或者可能会影响病毒的复制和传播能力。已知的ICP0/CIN85/Cb1相互作用的表现包括从感染细胞表面下调表皮生长因子受体(EGFR)和病毒进入受体Nectin-1。感染ICP0缺失病毒的细胞表面和感染野生型病毒后Cbl基因敲除的细胞表面均残留Nectin-1，导致病毒传播障碍。基于这些观察，该提议的中心假设是HSV-1通过ICP0与Cb1/CIN85复合体结合，促进细胞表面因子的内吞，改变信号反应，从而使其受益。我们设计了两个具体的目标来研究这一假说。目的1探讨ICP0与CIN85/Cb1复合体在HSV-1感染过程中的相互作用及其意义。在目标2中，我们建议确定ICP0在感染细胞中由Cb1/CIN85复合体介导的内吞作用。这些研究有望阐明ICP0与Cbl/CIN85内吞机制相互作用的重要性。这种相互作用可能导致细胞表面体的改变，从而影响细胞内信号传递和细胞间通讯。总体而言，这可能是病毒逃避宿主的一种策略。

Herpes simplex virus 1 has afflicted more than 80% of the population and can cause diseases that range in severity from benign cold sores to encephalitis. Following replication in mucosal epithelial cells the virus establishes latent reservoirs in sensory neurons that innervate the infected tissues. Reactivation of the virus in these neurons upon stress or weakened immune responses is the source of virus in recurrent disease. To infect and persist in the host, HSV-1 has evolved strategies to counteract host antiviral responses. The immediate early protein of the virus Infected Cells Protein No 0 (ICP0) has a fundamental role in this process. In vivo, ICP0 is essential for successful colonization of the host, for virus replication, and for efficient reactivation of the virus from neuronal latency. During the early steps of the infection, ICP0 localizes in the nucleus where it activates viral gene transcription by blocking repressors of the viral genome, by inducing viral chromatin remodeling, and by inhibiting antiviral responses. The onset of virus replication triggers translocation of ICP0 to the cytoplasm, where it resides for the remainder of the virus replication cycle. The functions of ICP0 out of the nucleus have only scantily been explored. ICP0 in the cytoplasm interacts with the adaptor protein CIN85, a binding partner of the Cbl E3 ligase, which has a major role in cell surface receptor internalization, endocytic processing and protein sorting. The virus via ICP0 appears to subjugate the endocytic machinery Cbl/CIN85 to eliminate surface components, which could initiate harmful signals or could affect the ability of the virus to replicate and spread. Known manifestations of the ICP0/CIN85/Cbl interactions include the down- modulation of the epidermal growth factor receptor (EGFR) and of the viral entry receptor Nectin-1 from the surface of the infected cells. Nectin-1 was retained on the surface of cells infected with an ICP0-null virus and on the surface of the Cbl-knockdown cells after infection with the wild type virus causing a defect in virus spread. Based on these observations, the central hypothesis of this proposal is that HSV-1 via ICP0 co- opts the Cbl/CIN85 complex to promote endocytosis of cell surface factors, to modify signaling responses, for its benefit. We have designed two Specific Aims to investigate this hypothesis. In Aim 1, we propose to interrogate the interaction of ICP0 with the CIN85/Cbl complex and its significance during HSV-1 infection. In Aim 2, we propose to define the role of ICP0 in endocytosis mediated by the Cbl/CIN85 complex in infected cells. These studies are expected to delineate the importance of interaction of ICP0 with the Cbl/CIN85 endocytic machinery. This interaction could lead to alterations of the cell surfaceome that could impact intracellular signaling and intercellular communication. Overall, this could be a strategy by which the virus evades the host.