Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA.
BIO5 Institute, University of Arizona, Tucson, Arizona, USA.
J Virol. 2018 Sep 26;92(20). doi: 10.1128/JVI.00919-18. Print 2018 Oct 15.
Human cytomegalovirus, HCMV, is a betaherpesvirus that establishes a lifelong latent infection in its host that is marked by recurrent episodes of reactivation. The molecular mechanisms by which the virus and host regulate entry into and exit from latency remain poorly understood. We have previously reported that is critical for reactivation, functioning in part by overcoming suppressive effects of the latency determinant We have demonstrated a role for in diminishing cell surface levels and targeting epidermal growth factor receptor (EGFR) for turnover. The attenuation of EGFR signaling promotes HCMV reactivation in combination with cellular differentiation. In this study, we sought to define the mechanisms by which functions in regulating EGFR turnover and viral reactivation. Screens to identify proteins interacting with pUL135 identified two host adaptor proteins, CIN85 and Abi-1, with overlapping activities in regulating EGFR levels in the cell. We mapped the amino acids in pUL135 necessary for interaction with Abi-1 and CIN85 and generated recombinant viruses expressing variants of pUL135 that do not interact with CIN85 or Abi-1. These recombinant viruses replicate in fibroblasts but are defective for reactivation in an experimental model for latency using primary CD34 hematopoietic progenitor cells (HPCs). These variants have altered trafficking of EGFR and are defective in targeting EGFR for turnover. These studies demonstrate a requirement for pUL135 interactions with Abi-1 and CIN85 for regulation of EGFR and mechanistically link the regulation of EGFR to reactivation. Human cytomegalovirus (HCMV) establishes a lifelong latent infection in the human host. While the infection is typically asymptomatic in healthy individuals, HCMV infection poses life-threatening disease risk in immunocompromised individuals and is the leading cause of birth defects. Understanding how HCMV controls the lifelong latent infection and reactivation of replication from latency is critical to developing strategies to control HCMV disease. Here, we identify the host factors targeted by a viral protein that is required for reactivation. We define the importance of this virus-host interaction in reactivation from latency, providing new insights into the molecular underpinnings of HCMV latency and reactivation.
人巨细胞病毒（HCMV）是一种β疱疹病毒，在其宿主中建立终身潜伏感染，其特征是反复出现再激活。病毒和宿主调节进入和退出潜伏的分子机制仍知之甚少。我们之前曾报道过， 对于再激活至关重要，部分功能是克服潜伏决定因素的抑制作用。我们已经证明了 在降低细胞表面水平和靶向表皮生长因子受体（EGFR）进行周转方面的作用。EGFR 信号的衰减与细胞分化相结合，促进 HCMV 的再激活。在这项研究中，我们试图确定 在调节 EGFR 周转和病毒再激活中发挥作用的机制。筛选识别与 pUL135 相互作用的蛋白质的筛选鉴定了两种宿主衔接蛋白 CIN85 和 Abi-1，它们在调节细胞中 EGFR 水平方面具有重叠的活性。我们绘制了 pUL135 与 Abi-1 和 CIN85 相互作用所必需的氨基酸，并生成了表达不与 CIN85 或 Abi-1 相互作用的 pUL135 变体的重组病毒。这些重组病毒在成纤维细胞中复制，但在使用原代 CD34 造血祖细胞（HPC）的潜伏实验模型中再激活缺陷。这些 变体改变了 EGFR 的运输，并且在针对 EGFR 进行周转方面存在缺陷。这些研究表明，pUL135 与 Abi-1 和 CIN85 的相互作用是调节 EGFR 的必需条件，并从机制上将 EGFR 的调节与再激活联系起来。人巨细胞病毒（HCMV）在人类宿主中建立终身潜伏感染。虽然在健康个体中感染通常无症状，但 HCMV 感染在免疫功能低下的个体中构成危及生命的疾病风险，是出生缺陷的主要原因。了解 HCMV 如何控制终身潜伏感染和从潜伏中复制的再激活对于制定控制 HCMV 疾病的策略至关重要。在这里，我们确定了一种病毒蛋白靶向的宿主因子，该蛋白是再激活所必需的。我们定义了这种病毒-宿主相互作用在潜伏再激活中的重要性，为 HCMV 潜伏和再激活的分子基础提供了新的见解。
