Hepatitis B virus transcriptional interference and liver cancer-related mutations

乙型肝炎病毒转录干扰与肝癌相关突变

基本信息

批准号：
9089897
负责人：
SHUPING TONG
金额：
$ 24.15万
依托单位：
RHODE ISLAND HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-06-15 至 2018-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9089897
关键词：
Address Biological CMV promoter Capsid Cell Proliferation Chronic Chronic Hepatitis B Circular DNA Core Protein DNA biosynthesis Development Epidemiologic Studies Genetic Transcription Genome Glycine decarboxylase Health Hepatitis B Hepatitis B Surface Antigens Hepatitis B Virus Hepatitis B e Antigens Hepatocarcinogenesis Hepatocyte Immune Tolerance Infection Length Link Malignant neoplasm of liver Medical Molecular Biology Monitor Mutation Nature Patients Phase Polyadenylation Polymerase Positioning Attribute Primary carcinoma of the liver cells Production Protein S Proteins RNA Risk Signal Transduction Specific qualifier value Staging Testing Time Trans-Activators Transcript Transcriptional Regulation Transgenic Mice Translating Translations Up-Regulation Viral Viral Genome Virion Virus Work ds-DNA env Gene Products immune clearance immunogenic in vivo mutant novel overexpression particle promoter protein expression vector viral RNA

项目摘要

DESCRIPTION (provided by applicant): Establishment of chronic hepatitis B virus (HBV) infection requires induction of immune tolerance by hepatitis B e antigen (HBeAg) and excess envelope proteins in the form of subviral particles. The subsequent immune clearance phase rather selects for core promoter mutations and SPII promoter deletions. Both types of mutations and HBx protein, a transcriptional transactivator, have been implicated in the development of hepatocellular carcinoma (HCC). The core promoter drives transcription of the 3.5-kb pc RNA for HBeAg and slightly shorter pg RNA for genome replication, while the SPII promoter drives the 2.1-kb RNA for the middle and small (S) envelope proteins. Core promoter mutations diminish HBeAg expression but enhance genome replication through transcriptional up regulation of pg RNA at the expense of pc RNA. Surprisingly, mutations conferring the highest level of genome replication reduced S protein level. Since all the four classes of HBV transcripts are unidirectional and co-terminal at the 3' end, our interpretation is that the 3.5-kb RNAs interfere with transcription of the 2.1-kb RNA by promoter occlusion. To verify this hypothesis, the impact of deleting the core promoter or replacing it with the strong CMV promoter on transcription of the 2.1-kb RNA will be determined. To examine whether the 2.1-kb RNA interferes with transcription of the 0.7-kb RNA for HBx protein, we will establish whether SPII promoter deletions found in HCC patients up regulate HBx transcript. Finally, since the 3' end of all the transcripts overlaps with the 5' end of the terminally redundant 3.5-kb RNAs, the abundant 2.1-kb RNA has the potential to inhibit transcription of the 3.5-kb RNAs. This will be verified by examining the replication impact of SPII promoter deletions in the context of a circularized HBV genome in contrast to vector-linked dimeric construct. We propose that bidirectional transcriptional interference allows HBV to effectively coordinate its genome replication with envelope and HBx protein expression. We previously found that core promoter mutations enable the HBx protein expressed alone (and at high level) to trigger cell proliferation. Transcriptional interference will allow SPII promoter deletions to markedly augment HBx protein expression from the intact genome. Thus, the two types of mutations could work synergistically with HBx protein to promote hepatocarcinogenesis. In summary, this application explores a novel mechanism of HBV transcriptional regulation and at the same time connects the three viral factors in HCC development.

描述（申请人提供）：慢性乙型肝炎病毒（HBV）感染的建立需要乙型肝炎e抗原（HBeAg）和亚病毒颗粒形式的过量包膜蛋白诱导免疫耐受，随后的免疫清除阶段则选择核心。启动子突变和 SPII 启动子缺失。这两种类型的突变和 HBx 蛋白（一种转录反式激活蛋白）均与肝细胞癌 (HCC) 的发展有关。 HBeAg 的 3.5-kb pc RNA 和用于基因组复制的稍短的 pg RNA 的转录，而 SPII 启动子驱动中和小 (S) 包膜蛋白的 2.1-kb RNA 突变会减少 HBeAg 表达，但会增强基因组复制。令人惊讶的是，由于所有四类 HBV 转录物都是单向的，因此基因组复制的最高水平的突变降低了 S 蛋白水平。在 3' 末端共末端，我们的解释是 3.5-kb RNA 通过启动子封闭干扰 2.1-kb RNA 的转录。为了验证这一假设，删除核心启动子或用强 CMV 替换它的影响。将确定 2.1-kb RNA 转录的启动子为了检查 2.1-kb RNA 是否干扰 HBx 蛋白的 0.7-kb RNA 转录，我们将确定。 HCC 患者中发现的 SPII 启动子缺失是否上调 HBx 转录本最后，由于所有转录本的 3' 末端与末端冗余的 3.5-kb RNA 的 5' 末端重叠，因此丰富的 2.1-kb RNA 有可能抑制。这将通过检查 SPII 启动子删除在环化 HBV 基因组中与载体连接的二聚体的复制影响来验证。我们提出，双向转录干扰使 HBV 能够有效地协调其基因组复制与包膜和 HBx 蛋白的表达。我们之前发现，核心启动子突变使 HBx 蛋白单独表达（且高水平），从而触发细胞增殖。转录干扰将使 SPII 启动子缺失显着增强完整基因组中 HBx 蛋白的表达，因此，这两种类型的突变可以与 HBx 蛋白协同作用，促进肝癌发生。总之，本申请探索了 HBV 转录调控的新机制。同时将肝癌发展中的三种病毒因素联系起来。