未折叠蛋白响应诱导的转录因子ATF4在巨细胞病毒复制中的作用机制研究

Human cytomegalovirus (HCMV) infection is one of the leading causes of birth defect. Its primary infection and reactivation also cause severe and even life threatening diseases in immunocomprimised individuals. We have reported that HCMV protein pUL38 upregulates the expression of transcription factor ATF4 to prevent the apoptosis of infected cells and facilitate virus replication. Our unpublished data indicated that ATF4 was also required for murine CMV (MCMV) to replicate efficiently in vitro, suggesting an evolutionary conserved function of ATF4 in CMV infection. We found that treating the pUL38-deficient HCMV infected cells with a ROS scavenger prevented premature cell death of the infected cells, and partially rescued virus growth. This preliminary data is consistent with the well documented role of ATF4 in maintaining the intracellular redox homeostasis. Thus, we propose that CMV infection upregualtes ATF4 to maintain the redox homeostasis of infected cells, which in turn facilitates virus replication. In order to test our hypothesis, we will design experiments to address the following three key questions: 1) dissecting the molecular mechanism by which CMV infection upregulates ATF4; 2) elucidating the function and mechanism of maintaining the redox homeostasis by ATF4 during CMV infection; 3) testing whether disrupting the redox homeostasis by small molecules can inhibit CMV replication. This study will provide new insights into the role of ATF4 in mediating an important host virus interaction, and potentially leads to new approaches to control CMV infection and its related diseases.

人巨细胞病毒（HCMV）感染是造成新生儿缺陷的主要病因之一，也是在免疫缺陷病人中引起严重并发症甚至死亡的重要致病因素。我们已经报道HCMV蛋白pUL38通过上调转录因子ATF4抑制细胞凋亡并促进病毒复制，我们未发表的数据还表明ATF4对小鼠巨细胞病毒复制同样重要。本课题前期研究发现利用活性氧（ROS）清除剂可以抑制pUL38缺失病毒感染引起的细胞凋亡，并部分恢复该病毒的复制能力。这一数据与已知的ATF4在维持细胞内氧化还原平衡的功能相一致。因此我们提出以下假说：CMV感染通过上调ATF4以维持细胞内的氧化还原平衡，从而实现病毒高效复制。本研究将围绕这一假说，进一步探索1）CMV上调ATF4的分子机制；2）ATF4维持的氧化还原平衡在CMV感染中的功能及其分子机制；3）通过改变细胞内氧化还原平衡抑制CMV复制。本研究有望为CMV感染及相关疾病提供新的理论基础和思路。

人巨细胞病毒（HCMV）是广泛感染的机会性病原体，它是造成新生儿缺陷的主要病因之一，还在免疫缺陷病人中引起严重并发症甚至死亡。本课题从病毒抵御宿主细胞应激反应，维持病毒高效复制角度开展研究，拟阐明参与该通路的病毒和宿主因子的作用机制，为控制HCMV感染及相关疾病提供新的思路和理论基础。我们已经报道HCMV蛋白pUL38通过上调转录因子ATF4抑制细胞凋亡并促进病毒复制。基于ATF4在调控氧化应激反应中的重要功能，我们发现利用活性氧（ROS）清除剂Tiron可以抑制pUL38缺失病毒感染引起的细胞凋亡，并部分恢复该病毒的复制能力。在这为期一年的短期资助研究中，我们围绕pUL38和ATF4调控细胞应激反应的机制研究开展工作，取得了以下进展：（1）利用亲和纯化和质谱分析发现了新的pUL38相互作用蛋白。（2）利用基因突变分析发现了新的pUL38功能基序。（3）比较了野生型和pUL38缺失突变病毒感染过程中ATF4下游基因的表达差异。（4）发现pUL38突变病毒引起的细胞凋亡能够被细胞内钙离子浓度调节剂所抑制。以上进展有助于深入阐明pUL38和ATF4调控细胞应激反应、促进HCMV病毒复制的分子机制，为后续研究打下了坚实的基础；实现了一年期小额资助探索性项目的研究目标，相关研究工作在整理发表过程中。