Retinoblastoma (Rb) protein pathway in human cytomegalovirus infected cells

描述（由申请方提供）：人巨细胞病毒（HCMV）是一种普遍存在的重要病原体，可刺激细胞周期进程。HCMV是心血管疾病的辅因子，具有显著的增殖成分，如冠状动脉再狭窄和移植血管硬化（TVS），并且可能在某些类型的癌症中起作用，最值得注意的是恶性胶质瘤（GBM）。细胞增殖和转化受视网膜母细胞瘤家族的肿瘤抑制因子（Rb、p107和p130）调节。Rb蛋白与转录因子的E2 F家族结合，调节DNA复制所需的细胞基因的表达，例如从头途径的核苷酸生物合成酶（NBE），以及参与伤口愈合和血管生成的分泌因子。当Rb蛋白的低磷酸化形式与E2 F蛋白结合时，E2 F应答基因的表达被抑制。低磷酸化Rb蛋白的降解或其过度磷酸化破坏了它们与E2 F的复合物，从而允许游离E2 F激活基因表达。HCMV编码调节Rb-E2 F途径的四种蛋白质：pp 71、IE 1、IE 2和本申请的重点UL 97。由于HCMV与增殖性疾病相关，并编码多种调节Rb-E2 F途径的蛋白，我们假设Rb-E2 F途径在HCMV复制和发病机制中起关键作用。在这里，我们建议探讨Rb，E2 F和UL 97蛋白在HCMV感染过程中的作用。UL 97是保守的疱疹病毒蛋白激酶（CHPKs）家族的成员，其直接磷酸化Rb蛋白并使其失活，导致细胞E2 F应答基因的诱导。我们假设这些E2 F反应基因产物（NBE）中的一些负责UL 97介导的病毒DNA复制的刺激。我们进一步推测，由UL 97诱导的其他E2 F反应基因产物（分泌的伤口愈合和血管生成因子）可能反过来部分负责与HCMV感染相关的增殖性病理，如再狭窄，TVS和GBM。该项目的长期目标是确定UL 97和其他HCMV蛋白如何通过细胞自主和非细胞自主方式影响细胞周期进程、HCMV复制和病毒发病机制，并利用这些信息设计治疗与HCMV感染相关的增殖性疾病的疗法。PHS 398/2590（Rev. 05/01）第1页

DESCRIPTION (provided by applicant): Human cytomegalovirus (HCMV) is a ubiquitous and significant pathogen that stimulates cell cycle progression. HCMV is a cofactor for cardiovascular diseases with significant proliferative components such as coronary restenosis and transplant vascular sclerosis (TVS), and may play a role in certain types of cancers, most notably, malignant gliomas (GBMs). Cellular proliferation and transformation is regulated by the retinoblastoma family of tumor suppressors (Rb, p107, and p130). The Rb proteins, in conjunction with the E2F family of transcription factors, regulate the expression of cellular genes required for DNA replication such as nucleotide biosynthetic enzymes (NBEs) of the de novo pathway, as well as secreted factors involved in wound healing and angiogenesis. The expression of E2F-responsive genes is inhibited when the hypophosphorylated forms of the Rb proteins are bound to the E2F proteins. Degradation of the hypophosphorylated Rb proteins, or their hyperphosphorylation disrupts their complexes with E2F, thus allowing free E2F to activate gene expression. HCMV encodes four proteins that modulate the Rb-E2F pathway: pp71, IE1, IE2, and the focus of this application, UL97. Because HCMV is associated with proliferative diseases and encodes multiple proteins that modulate the Rb-E2F pathway, we hypothesize that the Rb-E2F pathway plays a critical role in HCMV replication and pathogenesis. Here we propose to explore the roles of the Rb, E2F, and UL97 proteins during HCMV infection. UL97 is a member of a family of conserved herpesvirus protein kinases (CHPKs) that directly phosphorylates the Rb protein and inactivates it, leading to the induction of cellular E2F-responsive genes. We hypothesize that some of these E2F-responsive gene products (the NBEs) are responsible for the UL97-mediated stimulation of viral DNA replication. We further speculate that other E2F-responsive gene products induced by UL97 (secreted wound healing and angiogenesis factors) may in turn be partially responsible for proliferative pathologies associated with HCMV infection, such as restenosis, TVS, and GBMs. The long-term goal of this project is to determine how Rb inactivation by UL97 and other HCMV proteins impacts cell cycle progression, HCMV replication, and viral pathogenesis in both cell autonomous and non-cell-autonomous manners, and to use this information to design therapies to treat proliferative diseases associated with HCMV infection. PHS 398/2590 (Rev. 05/01) Page 1 Continuation Format Page