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型已经折磨了超过80%的人口，并可引起从良性唇疱疹到脑炎的严重程度不等的疾病。在粘膜上皮细胞中复制后，病毒在支配受感染组织的感觉神经元中建立潜伏的储库。这些神经元中的病毒在应激或免疫反应减弱时重新激活是复发性疾病中病毒的来源。为了感染宿主并在宿主中持续存在，HSV-1已经进化出抵消宿主抗病毒反应的策略。病毒感染细胞蛋白No 0（ICP 0）的立即早期蛋白在这一过程中起着重要作用。在体内，ICP 0对于宿主的成功定殖、病毒复制和病毒从神经元潜伏期的有效再活化是必不可少的。在感染的早期阶段，ICP 0定位于细胞核中，在那里它通过阻断病毒基因组的阻遏物、诱导病毒染色质重塑和抑制抗病毒反应来激活病毒基因转录。病毒复制的开始触发ICP 0易位到细胞质中，在病毒复制周期的剩余部分中它驻留在细胞质中。ICP 0在细胞核外的功能还很少被探索。细胞质中的ICP 0与衔接蛋白CIN 85相互作用，CIN 85是Cbl E3连接酶的结合伴侣，其在细胞表面受体内化、内吞加工和蛋白质分选中起主要作用。通过ICP 0的病毒似乎征服了内吞机制Cbl/CIN 85以消除表面组分，这可能引发有害信号或可能影响病毒复制和传播的能力。ICP 0/CIN 85/Cbl相互作用的已知表现包括表皮生长因子受体（EGFR）和病毒进入受体Nectin-1从感染细胞表面的下调。Nectin-1保留在用ICP 0-无效病毒感染的细胞的表面上，以及在用野生型病毒感染后在Cbl-敲减细胞的表面上，导致病毒传播缺陷。基于这些观察结果，该提议的中心假设是HSV-1通过ICP 0与Cbl/CIN 85复合物共选择以促进细胞表面因子的内吞作用，从而改变信号传导应答，以获得其益处。我们设计了两个特定的目标来研究这个假设。在目的1中，我们提出询问ICP 0与CIN 85/Cbl复合物的相互作用及其在HSV-1感染期间的意义。在目的2中，我们提出定义ICP 0在感染细胞中由Cbl/CIN 85复合物介导的内吞作用中的作用。这些研究有望阐明ICP 0与Cbl/CIN 85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组的改变，从而影响细胞内信号传导和细胞间通讯。总的来说，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.